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  • POWER HOLDING COMPANY OF NIGERIA PLCNATIONAL CONTROL CENTRE OSOGBO GENERATION AND TRANSMISSION GRID OPERATIONS 2007 (ANNUAL TECHNICAL REPORT) ISSUED BY: GENERAL MANAGER (S/O) NATIONAL CONTROL CENTRE OSOGBO FEBRUARY, 2008. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo
  • TABLE OF CONTENTS PAGES INTRODUCTION 11.0 GRID OPERATIONS IN 2007 1 1.1 Hydrology and Lake Operation. 1 1.2 Thermal Generation 9 1.3 Generation Ordering and Load Dispatching 19 1.4 Frequency Control 19 1.5 Voltage Control 19 1.6 Outage Planning 22 1.7 Energy Production 292.0 CONSTRAINTS TO GRID OPERATIONS 41 2.1 Constraints to Grid vis-a-vis System Communication 41 2.2 Generation Constraints 49 2.3 Transmission Constraints 493.0 REINFORCEMENT AND REHABILITATION OF NATIONAL GRID 624.0 SYSTEM DISTURBANCES 66 4.1 Transmission System faults 66 4.2 Generation System faults 665.0 ACCIDENTS AND MISHAPS 666.0 CONCLUSIONS AND RECOMMENDATIONS 677.0 APPENDICES 71 (i) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo
  • NO. LIST OF TABLES PAGE1A. HYDROLOGICAL SUMMARY 31B COMP. AVE.INFLOW AND TURB.DISCH. 62 AVERAGE MONTHLY MW AVAILABILITY 123 SUMMARY OF GENERATION CAPABILITIES OF PHCN POWER 20 STATIONS AS OPERATED IN 20074. PHCN POWER SYSTEM FREQUENCY 275A. 2007 OUTAGES STATISTICAL SUMMARY 330KV LINE 295B. 2006 OUTAGES STATISTICAL SUMMARY 330KV LINE 296A. 2007 OUTAGES STATISTICAL SUMMARY 132KV LINE 306B. 2006 OUTAGES STATISTICAL SUMMARY 132KV LINE 307. ENERGY GENERATED (MWH) 388. HYDRO & THERMAL ENERGY GENERATED(MWH) 399. ENERGY GENERATION & POWER CONSUMPTION RECORDS 4310. MONTHLY ENERGY BALANCE SUMMARY 4611 ENERGY AVAILABLE FOR SALES PLUS DISTRIBUTION LOSSES IN EACH REGION (MW) 4712 TOTAL GAS CONSUMED 4813 COST OF GAS (NAIRA) AGAINST ENERGY GENERATED 2007 4914 OPERATING FUEL COST (NAIRA/KWh) 5015 MONTHLY MAXIMUM DEMAND/GENERATION ANALYSIS (MWH) 8416 SYSTEM GENERATION PEAK LOAD (FORECAST & ACTUAL) 8517 SUMMARY OF OCCURRENCE MAXIMUM PEAK LOAD 8618 SUMMARY OF SYSTEM DISTUBANCES 10719A SUMMARY OF SYSTEM DISTUBANCES OF INTEGRATED GRID 10819B SUMMARY OF GRID COLLAPSES 10919C SUMMARY OF SYSTEM DISTURBANCES OF INTEGRATED GRID OPERATIONS 110 (ii) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo
  • NO. CHARTS PAGE1. KAINJI AVERAGE MONTHLY TOTAL DISCHARGE AND INFLOW 42. KAINJI HYDROGRAPH 43. JEBBA AVERAGE MONTHLY TOTAL DISCHARGE AND INFLOW 84. JEBBA HYDROGRAPH 85. SHIRORO AVERAGE MONTHLY TOTAL DISCHARGE AND INFLOW 96. SHIRORO HYDROGRAPH 97. 2007 AVERAGE MONTHLY MW AVAILABILITY 148. POWER STATIONS AVAILABILITY FACTOR 149 POWER STATIONS AVERAGE MW AVAILABILITY 2110 POWER STATIONS INSTALLED CAPACITY 2111 ANNUAL ENERGY GENERATED. 2512 SIMULTANEOUS NATIONAL PEAK DEMAND (MW) 2513 330KV FORCED OUTAGES (2006 & 2007) 3214 132KV FORCED OUTAGES (2006 & 2007) 3215 COMBINED 2006 & 2007 330KV OUTAGES. 3316 COMBINED 2006 & 2007 132KV OUTAGES. 3317 330KV PLANNED, URGENT AND EMERGENCY OUTAGES 3418 132KV PLANNED,URGENT & EMERGENCY OUTAGES 3419 PERCENTAGE ENERGY USED IN POWER STATIONS 4020 HYDRO, THERMAL AND TOTAL ENERGY GENERATED 4021 ENERGY GENERATED IN HYDRO POWER STATIONS 4222 ENERGY GENERATED IN MAJOR THERMAL POWER STATIONS 4223 AVAILABLE ENERGY FOR SALES 4424 TOTAL MONTHLY ENERGY AVAILABLE FOR SALE 4425 TRANSMISSION REGIONS: MONTHLY ENERGY AVAILABLE FOR SALE 51 (iii) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo
  • NO. CHARTS PAGE 26 REGIONAL ENERGY AVAILABLE FOR SALE 51 27 MAJOR THERMAL STATIONS FUEL COST 52 28 MONTHLY UNIT PROD. COST (NAIRA/UNIT) 53 29 STATIONS AVE. PROD. COSTS (NAIRA/UNIT) 54 30 MONTHLY PEAK DEMAND FORECAST AND ACTUAL GENERATION 87 31 WEEKLY PEAK GENERATION 87 32 KAINJI G.S. USABLE GEN. CAP. SPECTOGRAPH PLOT AVAILABLE 88 33 JEBBA G.S. USABLE GEN. CAP. SPECTOGRAPH PLOT AVAILABLE 88 34 SHIRORO P.S. USABLE GEN. CAP. SPECTOGRAPH 89 35 EGBIN P.S. USABLE GEN. CAP. SPECTOGRAPH 89 36 DELTA P.S. USABLE GEN. CAP. SPECTOGRAPH 90 37 AFAM P.S. USABLE GEN. CAP. SPECTOGRAPH 90 38 SAPELE P.S. USABLE GEN. CAP. SPECTOGRAPH 91 39 OMOTOSHO P.S. USABLE GEN. CAP. SPECTOGRAPH 91 40 AES P.S. USABLE GEN. CAP. SPECTOGRAPH 92 41 OKPAI P.S. USABLE GEN. CAP. SPECTOGRAPH 92 42 GEREGU G.S. USABLE GEN. CAP. SPECTOGRAPH 93 43 OMOTOSHO G.S. USABLE GEN. CAP. SPECTOGRAPH 93 44 OMOKU P.S. USABLE GEN. CAP. SPECTOGRAPH 94 45 AJAOKUTA P.S. USABLE GEN. CAP. SPECTOGRAPH 94 46 OLORUNSOGO P.S. USABLE GEN. CAP. SPECTOGRAPH 95 47 DAILY TOTAL GRID GEN. AVAILABILITY STATUS 95 48 GRAPHICAL REPRESENTATION OF SYSTEM COLLAPSE (DAYS) 111 49 GRAPHICAL REPRESENTATION OF SYSTEM COLLAPSE (MONTHS) 111 50 SUMMARY OF SYSTEM DISTURBANCES 2007 112 51 LOAD LOSS DUE TO SYSTEM DISTURBANCES 112 (iv)Generation and Transmission Grid Operations-2006-National Control Centre, Osogbo
  • lNTRODUCTIONThis Technical Report, an annual publication of Power Holding Company Nigeria Plc(PHCN), covered the National Generation and Transmission Grid Operations in 2007. Itwas collated from NCC electronics data bank. Among the major headings elaborated onwere: • 1.0 Grid Operations in 2007. • 2.0 Constraints to Grid Operations in 2007. • 3.0 Reinforcements to the National Grid in 2007. • 4.0 System Disturbances, Accidents and Mishaps in 2007. • 5.0 Accidents and Mishaps • 6.0 Conclusions and Recommendations.Grid Operations in 2007 was compared with the preceding year 2006 and the previousyears through tables and graphs.Also presented are detailed analyses of plant and equipment outages, energy generated,transmitted and available to the distribution network.Depicted also are supplementary charts, graphs and other significant details that aidcomprehension of the report.1.0 GRID OPERATIONS IN 2007The plant average availability at Kainji Power Station in 2007 was 524.1MW. This was115.3MW higher than 2006 figure of 408.8MW.Jebba’s plant availability ranged between 578.4MW and 559.1MW in 2007 with averageavailability of 572.3MW. This was greater than 2006 average availability of 554.2MWby 4.9MW.At Shiroro Power Station plant availability throughout the year was little less than 2006.The availability varied between 600MW and 444.4MW in 2007. It stood at an average of524.8MW. This was just 5.1MW lower than 2006 figure of 529.9MW. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo
  • 1.1 HYDROLOGY AND LAKE OPERATIONS1.1.1. Kainji LakeThe average computed inflow of the 2006/2007 black flood yield into the Kainji Lakewas higher than the average forecast inflow by 8.98%.When the black flood inflow was compared with the figures of immediate past five yearsthe 2006/2007 black flood was higher than the 2005/2006 by 14.6%, higher than2004/2005 by 34.54%, lower than 2003/2004 by 14.78%, higher than 2002/2003 by22.21%, lower that 2001/2002 by 9.4%.The fairly, good flood yield, brought the head water elevation to 141.69 meterscorresponding to a volume of 11.95 billion cubic metres of water at the beginning of thehydro year, January 1st 2007.The black flood peaked on 8th December 2006, with a value of 1724 cubic metres persecond (m3/sec).This was (2.78%) higher than the peak daily computed black flood inflow of 2005/2006.At the Joint Operations/Generation Planning meeting held in Jebba HydroelectricBusiness Unit on the 7th - 8th March 2007, the planned turbine discharges and theexpected inflow into the Kainji Lake from the months of March through August were asin the Table1B. The importance of the meeting was to agree on the draw downtrajectory.The forecast inflow between January and June 2007 was 26.85% lower than the actualcomputed inflow. It was noted that the actual turbine discharge during the period fellshort by (1.24%) of the planned discharge, in spite of the fairly robust inflow. This was aresult of fall in Kainji MW availability.Also during this period while the Kainji MW was low and Jebba MW availability washigher, hence the amount of inflow into the Jebba Lake was not good enough to keep thehead water elevation high for efficient Power Generation. It became necessary to engageon controlled spillage, to sustain Jebba Operations. Between January and April a totalaverage volume of water spilled was 1405.56 cubic metres per second.The difference of 641.66 m3/sec between the average computed total station discharge of1213.61 m3/sec and the average total computed inflow rate of 571.95 m3/sec resulted inthe drawing down of the Lake to an elevation of 130.44 metres by June 28, 2007.This corresponded to a storage balance of 1.38 billion cubic metres of water. Thisvolume was 0.37 billion cubic metres lower than the lowest volume attained on July 24,2006. It was observed that, the volume attained in 2007 was the lowest ever since theinception of the Kainji Lake Operations 1968. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 2
  • TABLE 1A: HYDROLOGICAL SUMMARY. JANUARY - DECEMBER 2007 AVE.TURB.DISCH. AVE.SPILLAGE STATION AVE.TOT. DISCH COMP.AVE. INFLOW AVE.DAILY ENERGY (CUB.M/SEC) (CUB.M/SEC) (CUB.M/SEC) RATE (CUB.M/SEC) (MWH)MONTH KAINJI JEBBASHIROROKAINJI JEBBASHIRORO KAINJI JEBBA SHIRORO KAINJI JEBBASHIRORO KAINJI JEBBA SHIRORO JAN. 856.13 1419.48 368.84 457.10 0.00 0.00 1313.23 1419.48 368.84 1294.61 1353.77 54.39 7321.87 7864.77 8222.48 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo FEB. 774.86 1372.57 319.25 541.43 0.00 0.00 1316.29 1372.57 319.25 1069.07 1347.79 27.96 6680.48 7608.39 6921.00 MAR. 1189.32 1288.23 214.81 275.90 0.00 0.00 1465.22 1288.23 214.81 399.74 1379.55 13.19 9670.42 7212.52 4434.10 APR. 1345.23 1669.67 144.73 131.13 0.00 0.00 1476.36 1669.67 144.73 277.80 1572.60 31.47 9938.73 9026.90 3058.93 MAY. 1176.13 1381.16 168.51 0.00 0.00 0.00 1176.13 1381.16 168.51 179.94 1287.84 69.13 8132.87 7544.32 3354.00 JUN. 534.43 653.67 232.17 0.00 0.00 0.00 534.43 653.67 232.17 210.53 676.83 200.43 3608.41 3619.00 4380.87JAN-JUN 5876.10 7784.78 1448.31 1405.56 0.00 0.00 7281.66 7784.78 1448.31 3431.69 7618.38 396.57 45352.78 42875.90 30371.38 TOTALJAN-JUN 979.35 1297.46 241.39 234.26 0.00 0.00 1213.61 1297.46 241.39 571.95 1269.73 66.10 7558.80 7145.98 5061.90AVERAG 3 JUL. 324.03 451.48 362.16 0.00 0.00 0.00 324.03 451.48 362.16 562.48 451.87 527.71 2168.61 2528.77 6870.13 AUG. 833.68 1027.81 376.71 0.00 0.00 0.00 833.68 1027.81 376.71 2209.19 1342.35 1048.87 5366.56 6112.32 7765.71 SEP. 1152.17 2078.80 444.00 0.00 0.00 0.00 1152.17 2078.80 444.00 2620.27 2171.87 951.50 8214.07 12028.07 9532.90 OCT. 1267.74 1988.65 321.29 0.00 0.00 0.00 1267.74 1988.65 321.29 1457.19 1709.45 249.32 9901.06 11106.97 7487.29 NOV. 1248.93 1394.10 321.23 192.50 0.00 0.00 1441.43 1394.10 321.23 1213.2 1514.80 96.17 9876.63 7655.13 7362.63 DEC. 1392.26 1240.23 194.97 0.00 0.00 0.00 1392.26 1240.23 194.97 1307.77 1422.39 38.52 10722.55 7324.00 4356.03JUL-DEC 6218.81 8181.06 2020.36 192.50 0.00 0.00 6411.31 8181.06 2020.36 9370.10 8612.73 2912.09 46249.48 46755.26 43374.70 TOTALJUL-DEC 1036.47 1363.51 336.73 32.08 0.00 0.00 1068.55 1363.51 336.73 1561.68 1435.46 485.35 7708.25 7792.54 7229.12AVERAGANNUAL 12094.91 15965.84 3468.67 1598.06 0.00 0.00 13692.97 15965.84 3468.67 12801.79 16231.11 3308.66 91602.26 89631.16 73746.08 TOTALAVERAG 1007.91 1330.49 289.06 133.17 0.00 0.00 1141.08 1330.49 289.06 1066.82 1352.59 275.72 7633.52 7469.26 6145.51 E
  • KAINJI AVE.MONTHLY TOT. DISCHARGE & INFLOW JANUARY-DECEMBER 2007, CHART 1 (SEE TABLE 1) 2800 2400 FLOW IN CUBIC METRES/SEC 2000 1600 1200 800 400 0 JAN. FEB. MAR. APR. MAY. JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS DISCHARGE INFLOW KAINJI HYDROGRAPH 1994-2007 CHART 2 144 142HEAD WATER ELEVATION IN METRES 140 138 136 134 132 130 JAN. FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS 2007ACTUAL 2006ACTUAL 2005ACTUAL 2004ACTUAL 2003ACTUAL 2002ACTUAL 2001ACTUAL 2000ACTUAL 1999ACTUAL 1998ACTUAL 1997ACTUAL 1996ACTUAL 1995 ACTUAL 1994 ACTUAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 4
  • The fast draw down was as a result of National demand as the gas supply to the ThermalPower Stations was unstable. To maintain supply during the nationwide elections andsubsequent inaugurations, all available water was used to generate power.At the Joint Operations/Generation Planning meeting held in Shiroro Hydro ElectricPLC, between 5th and 6th September 2007, the impoundment program from September2007 – February 2008 for the white flood and subsequent black flood was agreed on.Normally, it was convenient to fill the Kainji Lake to an elevation of 140.06 metrescorresponding to a volume of 10 billion cubic metres of water by the end of the whiteflood usually October ending.Records showed that the actual average computed inflow was slightly higher thanforecast inflow by 0.76%. The average actual turbine discharge during the white floodwas (17.65%) lower than the planned turbine discharge, because Kainji 1G6 which wasexpected to be on the grid in September was surprisingly unavailable.The peak of the computed white flood occurred on 1st September 2007, with a magnitudeof 4660 m3/sec. That magnitude was 1.75% higher than the peak value of 4580 m3/sec ofthe previous year which occurred on September 8, 2006.All the available units in Kainji Power station were kept running to avoid spillage. It hasto be mentioned that, if the Kainji Lake was not drawn down to the lowest elevation ever,spillage was would have been inevitable.At that period, spillage in Kainji would have been undesirable for Jebba Lake whose headwater elevation was above 102.5 metres already.By the end October 2007, the Kainji Lake head water elevation was 140.04 metres,corresponding to almost 10.00 billion cubic metres as planned.Before the end of October, Jebba Lake head water was observed to have to be reduceddrastically, because Kainji turbine discharge was not high enough as the lateral inflowinto the Jebba Lake has dropped significantly.By October 30, 2007, the Jebba Lake head water elevation had dropped to 99.9 metres.For 13 days, from 1st – 13th November 2007, controlled spillage was embarked on Kainjispillway gate. An average of 192.50 m3/sec was spilled, to boost Jebba Lake.The head water elevation of the Kainji Lake was at 139.24 metres, corresponding to 9.08billion cubic metres by the month of December 31st, 2007. This volume was lower(31.61%) than the volume obtained by the same time 2006. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 5
  • TABLE1B: PLAN/ACTUAL COMP. AVE. INFLOW AND AVE. TURB. DISCH. (CUB.M/SEC). JANUARY - DECEMBER 2007. KAINJI JEBBA SHIRORO AVER.MON ACTUAL PLAN ACTUAL PLAN ACTUAL PLAN ACTUAL PLAN ACTUAL PLAN ACTUAL PLAN INF. LATERA TH INF. DISC. DISC. INF. INF. DISC. DISC. INF. INF. DISC. DISC. L INFJAN. 1121.00 1294.61 900.00 856.13 891.00 1353.77 920.00 49.84 1419.48 15.00 54.39 200.00 368.84 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboFEB. 568.00 1069.07 900.00 774.86 883.00 1347.79 950.00 11.07 1372.57 12.00 27.96 200.00 319.25MAR. 572.00 399.74 1200.00 1189.32 994.00 1379.55 900.00 22.65 1288.23 15.00 13.19 200.00 214.81APR. 200.00 277.80 1200.00 1345.23 1007.00 1572.60 850.00 96.97 1669.67 25.00 31.47 200.00 144.73MAY. 102.00 179.94 1000.00 1176.13 778.00 1287.84 758.00 90.97 1381.16 108.00 69.13 200.00 168.51JUN. 142.00 210.53 750.00 534.43 864.00 676.83 864.00 119.97 653.67 192.00 200.43 200.00 232.17 6JUL. 333.00 652.48 700.00 324.03 1307.00 451.87 1320.00 135.13 451.48 442.00 527.71 300.00 362.16AUG. 1629.00 2209.19 1080.00 833.68 1363.00 1342.35 1380.00 528.90 1027.81 794.00 1048.87 300.00 376.71SEP. 2526.00 2620.27 1374.00 1152.17 2311.00 2171.87 2020.00 1019.67 2078.80 1191.00 951.50 500.00 444.00OCT. 2084.00 1457.19 1374.00 1267.74 2109.00 1709.45 1909.00 449.48 1988.65 510.00 249.32 450.00 321.29NOV. 1556.00 1213.20 1410.00 1248.93 1492.00 1514.80 1492.00 62.63 1394.10 88.00 96.17 300.00 321.23DEC. 1644.00 1307.77 1410.00 1392.26 1434.00 1422.39 1500.00 44.97 1240.23 35.00 38.52 200.00 194.97
  • Overall Kainji MW availability was better (28.2%) than the figure of the previous year(see chart 1&2)1.1.2 Jebba LakeAt the beginning of the hydro year, 1st January 2007, the head water elevation at Jebbalake was at 100.96 metres, corresponding to 3.2875 billion cubic metres. This wasslightly higher (0.23%) than the storage balance of 3.28 billion cubic metres of waterrecorded at the beginning of 2006 hydro year.Appreciable lateral inflow into the Jebba Lake started on 25th August 2007, with a valueof 1223 m3/sec. It peaked on 28th August 2007 with a value of 1813 m3/sec and ebbedout after the second week of October. The peak value was higher (39.68%) than the peaklateral inflow recorded on September 17th, 2006.During the year, the minimum head water recorded, was 99.02 metres which occurred onJune 26th, 2007.The maximum station turbine discharge of 2266 m3/sec occurred on September 10, 2007,and the maximum computed inflow of 2876 m3/sec occurred on August 28, 2007.When the head water elevation was 102.73 metres on September 9th, 2007, the six unitswere run for 24 hours for almost 12 days.Due to unstable gas supply to the Thermal Power Plants, great demand was on the hydroplants. This head water elevation (102.73metres) corresponded to a storage balance of3.803 billion cubic metres (see chart 3 &4)From Table 2, Jebba MW availability was higher than the previous year by 3.27%. Eventhough Kainji MW availability improved this year, it was evident from Table 1A themonthly average turbine discharge which was the primary source of inflows into JebbaLake was always lower than Jebba turbine discharge because of its MW availability. Forthis reason the head water elevation in Jebba lake was always drawn down early in theyear.By the end of the year, December 31st 2007, the head water elevation in Jebba was102.74 metres, corresponding to 3.805 billion cubic metres of water. This was 15.65%higher than the headwater of the Lake at the same period 2006.1.1.3 Shiroro LakeAt the beginning of the hydro year, January 1st 2007, the reservoir head water elevationwas 376.29 metres corresponding to a storage balance of 4.2678 billion cubic metres ofwater. This volume was lower (6.68%) than the storage balance at the same time 2006. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 7
  • JEBBA AVE. MONTHLY TOTAL DISCHARGE & INFLOW JANUARY-DECEMBER 2007, CHART 3 (SEE TABLE 1) 2500 2000 FLOW IN CUBIC METRES/SEC 1500 1000 500 0 JAN. FEB. MAR. APR. MAY. JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS DISCHARGE INFLOW JEBBA HYDROGRAPH 1994-2007 CHART 4 103.5 103HEAD WATER ELEVATION IN METRES 102.5 102 101.5 101 100.5 100 99.5 JAN. FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS 2007ACTUAL 2006ACTUAL 2005ACTUAL 2004ACTUAL 2003ACTUAL 2002ACTUAL 2001ACTUAL 2000ACTUAL 1999ACTUAL 1998ACTUAL 1997ACTUAL 1996ACTUAL 1995 ACTUAL 1994 ACTUAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 8
  • SHIRORO AV. MONTHLY TOT. DISCHARGE & INFLOW JANUARY-DECEMBER 2007 CHART 5 (SEE TABLE 1 ). 1300 1200 1100 1000 FLOW IN CUBIC METRES/SEC 900 800 700 600 500 400 300 200 100 0 JAN. FEB. MAR. APR. MAY. JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS DISCHARGE INFLOW SHIRORO HYDROGRAPH 1994-2007, CHART 6 385 380HEAD WATER ELEVATION IN METRES 375 370 365 360 355 JAN. FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS 2007ACTUAL 2006 ACTUAL 2005 ACTUAL 2004 ACTUAL 2003ACTUAL 2002ACTUAL 2001ACTUAL 2000ACTUAL 1999ACTUAL 1998ACTUAL 1997ACTUAL 1996ACTUAL 1995ACTUAL 1994ACTUAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 9
  • The draw down plan of the Shiroro Lake between March and August 2007 was agreedupon at the Joint Operations/Generation Planning meeting held in Jebba HydroelectricBusiness Unit on the 7th & 8th March 2007, as displayed in table 1B.The actual computed inflow during the period was higher than the forecast inflow by19.97%. Total station turbine discharge exceeded the total computed by 1079.89 m3/sec.This resulted in drawing down the lake to an elevation 358.41 metres by July 13, 2007.The unstable gas supply from the Nigerian Gas Company forced the Operation to drawdown the lake to that all time low head water elevation. This elevation was lower theprevious year minimum elevation of 359.65 metres on July 15, 2006 by 0.1427 billioncubic metres.The pattern of flood yield into the Shiroro Lake this year can be described as sporadic.The flood peaked in August and substantial inflow was for short duration about threeweeks precisely. The peak value of computed inflow recorded was 3175 m3/sec onAugust 28, 2007. The forecast inflow was 794 m3/sec, while the actual computed inflowwas 1048.87 m3/sec. Hope rose that definitely the Lake will be filled during the floodseason.After the first twelve days in September the inflow ebbed out. The hope was suddenlydashed.Usually, it was planned to fill the lake within the first two weeks in October every year,but the disappointing inflow yield of September, torpedoed the plan.Maximum head water elevation attained during the flood was 379.37 metres onSeptember 30, 2007.When it became obvious that the lake could not be filled, water regulation started. Thehead water elevation improved 379.49 metres corresponding to 4.987 billion cubic metreson October 12, 2007.Since appreciable inflows were not expected into the Shiroro Lake, plans were drawn out,in order to manage the available water resource from October 2007 till mid-July 2008.Overall Shiroro MW availability throughout 2007, dropped slightly by 0.97%, whencompared with 2006 figure.By December 31st 2007, the head water elevation stood at 373.68 metres correspondingto a storage balance of 3.7188 billion cubic metres. This balance was 14.76% lower thanthe storage balance at the same time 2006. (See chart 5&6). Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 10
  • 1.2. THERMAL GENERATION1.20. GENERATION AVAILABILITYIn table 2, the average Power(MW) availability was depicted. Analysis of the year’sthermal availability was conducted employing the popular relevant statistical measures.Thermal plant average availability was 2535.0MW in 2007. Of this figure 699.5MW(27.59%) was contributed by the 3 Independent Power Producers (IPP). The thermalavailability was 60.99% of aggregate of Hydro and thermal availability of 4156.2MW in2007. It surpassed 2006 figure of 2396.4MW by 138.6MW.1.21 SAPELE G. S.Sapele ST1 generated from January to 23rd May, when it was on forced outage.Restored back on 26th, the unit remained synchronized to the grid till 6th September whenit tripped on high vibration.Between 13th September and 25th October the unit was available. It then went through a 3week outage to clear serious oil leakage on the generator. Tripped on 20th November onsupper heater very high temperature the unit was restored by November ending andgenerated through out December, 2007.Sapele ST2 which had been on outage since September, 2002 due to high bearingproblem was restored to the grid in August, 2007. It tripped on turbine high vibration on6th August. After a week of outage the unit was available till 31st August when it wasforced out of the grid for a week due to restricted earth fault. It generated throughoutSeptember until it tripped during the system disturbance early October.From 30th October to the 2nd week of November, the unit was available. It then tripped oncontrol oil pressure and remained unavailable throughout December, 2007.Sapele ST3 was unavailable since 28th May, 2006 due to faulty generator transformers.By 31st December, 2007, the unit was still unavailable.Sapele ST4 was forced out of the grid due to high winding temperature fault since thethird quarters of 1994. It was still unavailable by 31st December, 2007.Sapele ST5 has been on outage since 2nd March, 1986 when its unit transformer andassociated switchgear got burnt. The unit was unavailable by December, 31st 2007.Sapele ST6 tripped following System disturbance on the 29th September, 2005. Theensuing fire outbreak in the station destroyed the governor control cable. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 11
  • TABLE 2 AVERAGE MONTHLY MW AVAILABILITY JAN. TO DEC. 2007 THERMAL THERMAL THERMA HYDRO GRAND KAINJI JEBBA SHIROR EGBIN AJAOKU A.E.S SAPEL OKPAI AFAM DELTA GEREGU OMOK OMOTOS PAPALANT TOTALMONTHS TOTAL L TOTAL TOTAL TOTAL MW MW O MW MW TA MW MW E MW MW MW MW MW U MW HO MW O MW (PHCN) (IPP) MW MW MW MW MW JAN. 421.9 578.4 595.2 997.4 80.5 256.3 108.4 444.5 166.9 474.5 0.0 34.8 0.0 0.0 1827.6 735.5 2563.2 1595.5 4158.7 FEB. 375.6 561.2 444.4 831.1 91.7 212.4 0.0 91.7 447.4 57.0 435.7 0.0 67.2 0.0 1930.1 304.1 2234.2 1381.3 3615.5 MAR. 522.2 566.4 520.3 641.1 90.9 172.1 112.5 366.1 73.3 427.1 76.3 86.0 0.0 0.0 1421.2 624.1 2045.3 1608.9 3654.2 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo APR. 580.8 569.1 517.7 709.7 92.6 166.1 116.1 314.5 106.8 334.2 96.8 230.5 0.0 0.0 1456.3 711.1 2167.4 1667.6 3835.0 MAY. 601.1 578.4 454.8 752.3 94.0 200.5 85.2 387.1 232.6 346.1 330.8 72.5 0.0 0.0 1840.9 660.1 2501.0 1634.4 4135.4 JUN. 479.2 578.4 520.0 689.3 91.7 198.1 112.0 330.2 205.9 330.9 350.1 88.3 40.4 0.0 1820.3 616.6 2436.9 1577.6 4014.4JAN-JUN 2980.9 3431.9 3052.5 4620.9 541.4 1205.5 534.2 1934.0 1232.9 1969.7 1289.7 512.0 107.7 0.0 10296.5 3651.5 13948.0 9465.2 23413.2 TOTALJAN-JUNAVERAG 496.8 572.0 508.7 770.1 90.2 200.9 89.0 322.3 205.5 328.3 214.9 85.3 17.9 0.0 1716.1 608.6 2324.7 1577.5 3902.2 E JUL. 596.8 578.4 469.4 794.8 110.0 198.3 127.7 479.2 204.8 363.0 284.7 100.0 22.3 0.0 1907.4 777.5 2684.9 1644.5 4329.4 12 AUG. 545.2 562.9 585.5 709.7 110.0 238.0 197.4 479.2 204.8 311.8 392.4 96.0 67.0 0.0 1993.1 813.1 2806.2 1693.5 4499.7 SEP. 492.3 578.4 540.0 814.0 89.8 229.2 176.2 437.2 243.2 370.3 255.7 94.2 138.6 0.0 2087.9 760.6 2848.5 1610.7 4459.2 OCT. 555.3 578.4 595.5 660.0 5.0 234.2 81.8 456.0 265.8 381.7 276.0 75.0 153.9 0.0 1824.2 765.2 2589.4 1729.2 4318.6 NOV. 548.7 559.1 600.0 566.9 60.0 267.9 137.7 472.1 290.8 358.0 276.0 75.8 200.0 0.0 1889.3 815.9 2705.2 1707.7 4412.9 DEC. 570.6 578.4 454.8 660.0 55.0 266.3 120.0 468.9 295.2 311.0 230.5 75.0 231.9 123.4 2027.0 810.2 2837.2 1603.9 4441.1JUL-DEC 3308.9 3435.5 3245.1 4205.4 429.8 1434.0 840.9 2792.6 1504.4 2095.8 1715.3 516.0 813.8 123.4 11729.0 4742.6 16471.5 9989.5 26461.0 TOTALJUL-DECAVERAG 551.5 572.6 540.9 700.9 71.6 239.0 140.1 465.4 250.7 349.3 285.9 86.0 135.6 20.6 1954.8 790.4 2745.3 1664.9 4410.2 EANNUAL STN. 524.1 572.3 524.8 735.5 80.9 220.0 114.6 393.9 228.1 338.8 250.4 85.7 76.8 10.3 1835.5 699.5 2535.0 1621.2 4156.2AVERAG E
  • The unit was restored on the 3rd week of September, 2006. By November, 2006 itdeveloped bearing vibration trouble. It was virtually out of service in 2007 due to crackon the turbine blade and high vibration.1.22 AFAM P. S.Afam GT1 was out of service since last quarter of 1993. It remained out of service byDecember, 2007.Afam GT2 - scrapped.Afam GT3 out of service since February 1990 on damaged exciter and generator bearingproblem, still maintained its enoperatable state by December, 2007.Afam GT4 was unavailable due to rotor balancing and labyrinth seal problem since 1998.Afam GT5 was on outage due to excessive oil leakage from the generator betweenJanuary and the third week of February. It ran for only a week and was then shut downdue to smoke on the exciter.Tied in the first week of August, it rolled generation into the grid till 28th September,2007. It was on bars for 9 days before it tripped as a result of system disturbance.Having generated the last week of September, the unit tripped again on turbine main lubeoil low pressure. By 31st December, 2007, the unit was still out of service.Afam GT6 was unavailable throughout the year with the exception of the first five daysof January, having developed high turbine inlet temperature.Afam GT7 was unavailable in the year on burnt generator breaker and control cablefaults.Afam GT8 had been on outage since 3rd April, 1988 on damaged turbine and turbineblade failure.GT9’s major overhaul was suspended in the last quarter of 1995 and still on breakdownoutage since.GT10 supposed to be on rehabilitation since 2002 was still unavailable by December, 31st2007.GT11 was out of service in September 1997 due to the fatal fire outbreak at Afam P.S.though it was restored to service 2 weeks after, it sooned tripped on oil drain hightemperature and still out by 31st December, 2007.Afam GT12 was shutdown in August 1998 due to compressor blade failure. It was stillout of service at the expiration of 2007. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 13
  • 2007 AVE. MONTHLY MW AVAILABILITY JANUARY-DECEMBER 2007 CHART 7(SEE TABLE2) 2500 2000MONTHLY AVAILABILITY 1500 1000 500 0 J F M A M J J A S O N D MONTHS KAINJI JEBBA SHIRORO SAP.TOT AFAM EGBIN DELTA IJORA CALABAR AES OKPAI AJAOKU THMAL PHCN THMAL IPP HYDRO TOT GRAND TOT OMOKU POWER STATIONS AVAILABILITY FACTOR JANUARY-DECEMBER 2007, CHART 8(SEE TABLE 3) 1.20 AVAILABILITY FACTOR 1.00 0.80 0.60 0.40 0.20 0.00 ) O O O O RO M ST / ) T ) ) TA AS AS AS AS AS G R R SH G EA KU YD YD O LE SO G (G (G (G KU (G ST TO IR AI AO PE H H N AM S O TA SH U O KP E. N U M JI A EG SA AJ M EL BI R AF BB IN A. O O O LO EG ER D KA JE O G POWER STATIONS Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 14
  • Afam GT13 had been on outage due to turbine failure since February 1997. By the endof 2007, the unit was still unavailable.Afam GT14 which had been on outage due to compressor blade failure since April 1992was on outage by December, 2007.Afam GT15 had been out of service since 1995 and required major overhaul to comeback on stream.Afam GT16 which had compressor blades failure in 1992 was still unavailable by 31stDecember, 2007.Afam GT17 was out of service on ignition failure from January to October 21, 2007. Itcame back on stream briefly and was later shutdown for reliability test. By November,when the reliability test was over, it only generated for 2 days following which it wasshutdown due to bearing oil leakage. It was still on outage by December, 2007.GT18 was shutdown from January to 15th October to clear the accumulated condensateson the gas pipeline. It generated in the 2nd weekend, shutdown thereafter on low gaspressure. Returned to the grid in early November, the unit tripped a week after on lowgas pressure. Attempts to restore it failed as condensate problems surfaced. By 31stDecember, 2007, the unit was out of service.GT19 was out of service on high air intake differential pressure. The unit wassynchronized to the grid a week after. Between 14th and 23rd January, it went out ofservice on dirty air inlet filters. From 8th April to end of June, the unit was available.Out for a week on underfrequency, the unit was available thereafter till the expiration of2007.GT20 generated into the grid in the first 14 days of January. It was then shutdown due todirty air inlet filters till 16th March. On 25th March, it shutdown again due to air intakefilter leakages.The unit was available then till the end of 2007 except the third week of June when ittripped on high inlet temperature.Afam average plant availability was 166.9 MW in January 2007. The first half annualpeak of 232.6 MW was attained February.In the second half of the year, the peak average demand was 295.2 MW, recorded inDecember. The year’s average MW availability was 228.1MW. It was 147.8MW(189%) greater than 2006 figure of 80.30 MW. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 15
  • 1.23 DELTA P.S.Delta GT1 & GT2 had been scrapped.Delta GT3, 4 & 5 were out of service due to non-availability of the 81MVA 11/132kVtransformer since January 2006 and remained unavailable by the end of 2007.Delta GT6 was generally available in 2007. It only went out on a week outage onexcitation fault.Delta GT7 was available from January to mid May when it was on a week outage. It ranthereafter till the 3rd week in July when it was on forced outage for a week. By the 2ndweek of November, the unit developed compressor bleed valve trouble and was stillunavailable by 31st December, 2007.Delta GT8 was in service from January to 17th April. It developed serious oil leakagefrom reduction gear for a week and run till the 2nd week of September when it shutdowndue to faulty generator bleed valve position trouble. It thereafter generated in the 3rd and4th week of October but tripped in early November. It was thereafter synchronized to thegrid till the end of December, 2007.Delta GT9 was generally available through out the year except the outage to seal the oilleakage on its unit transformer between 7th and 18th February, 2007.Delta GT10 was available from January to 7th February. It then went on outage to sealthe oil leakage on the unit transformer. Returned to the grid by 18th February, the unit rantill the 1st week in September when it tripped on excitation trouble. After a week outagethe unit remained on the grid till 31st December, 2007.Delta GT11 was on the grid from January to 7th February when it was shutdown onplanned outage to seal oil leakage on its unit transformer. Restored to the grid on 18thFebruary, the generating unit was available till the end of 2007.Delta GT12 was available through out the year except the planned outage on the 3rd weekof July, 2007.Delta GT13 was available in the year 2007 except the 3rd week in July when it was onplanned outage and the last week of December when the unit was shutdown due toabnormal bearing problem.Delta GT14 was on the grid from January to the 3rd week of July when it was on plannedoutage. It then generated till mid October when it tripped on exhaust over temperature.By 31st December, 2007, the unit was still unavailable. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 16
  • Delta GT15 was available from January to March 2007. It developed starting problemand remained out of service by 31st December, 2007.Delta GT16 was still undergoing rehabilitation in 2007.Delta GT17 was out of service from January to 31st July 2007. It ran for 13 days inAugust. Thereafter, it was shutdown due to fire in the turbine accessory.Delta GT18 was available throughout 2007 except the last 3 weeks of August when itwas on outage due to high exhaust temperature.Delta GT19 had been on outage since April 1998 on combustion trouble. Rehabilitationwas still in been awaited by 31st December, 2007.Delta GT20 generated into the grid from January to 19th February 2007, when itdeveloped hydrogen gas leakage. By February 28 the unit was tied to the grid. It trippedagain by 1st April on faulty crank motor. Synchronized back on 14th April, the unitgenerated till 18th May when it tripped on ignition problem. The unit was then availablefrom mid June till 31st December, 2007.Delta monthly average availability was 474.5 MW in January 2007. That was the midyear peak generation. In the second half of the year, the peak demand was 381.7 MWrecorded in October, 2007.The Station’s annual average availability was 338.8MW. It was 31.21% lower than2006 value of 492.5 MW.1.24. EGBIN P.S.Egbin ST1 was available from January to April 2007. It was shutdown from 1st to 17thMay for condenser cleaning. The unit was then available till the last week of July when ittripped on control system failure. By the third week of September the unit was out forinspection.Restored to the grid by the 2nd week of November, the unit generated for a week. It wasthence available till 31st December, 2007 except a week of outage to clear its controlvalve problem.Egbin ST2 was available throughout the year except a week outage each in April andJune 2007.Egbin ST3 was on the grid from January to the tail end of January when it developedboiler problem. By 31st December, 2007 the unit was still unavailableEgbin ST4 generated from January to the first week in March, 2007. It then went onplanned outage till 21st March. It was shutdown for condenser cleaning in the third week Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 17
  • of June and went on planted outage in the last week of August. It was thereafter availabletill 31st December, 2007.Egbin ST5 was available from January to 20th March when it went on outage due togenerator breaker fault. It remained on bars thence.Egbin ST6 which tripped on 13th March, 2006 on furnace distortion remained unavailableby 31st December, 2007.Egbin plant generation availability was 997.4 MW in January, 2007. That was the peakavailability for the 1st half of the year (January to June). In the second half of the year,the peak plant generation availability of 814.0 MW was attained in September. Annualaverage generation availability was 735.5 MW. It fell short of 2006 value of 1005.5 MWby 26.80%.1.25 IJORA P.S.Ijora GT4 was awaiting commissioning throughout the year 2007.GT5 which had been on breakdown outage due to exhaust plenum fault since the thirdweek of March, 2006 was still unavailable by 31st December, 20071.26 CALABAR P.S.Calabar EE1 was unavailable since the 2nd week of March, 2002 on burnt bearing. By31st December, 2007 the unit was still unavailable.Calabar EE2 has been out of service due to abnormal noise since 31st March, 2005. Itwas still unavailable by 31 December, 2007GM2’s starting problem that commenced in June 2004, continued throughout 2007.1.27 AES – INDEPENDENT POWER PRODUCERS (IPP)AES Barge 202 was tied to the grid from January to December 2007, safe a week outagein the last week of January and the 2nd week of April when it was shutdown due to theNigeria Gas Company (NGC) pigging work.Barge 203 ran from January to 9th March. It then tripped on high bearing vibration. Tiedback in the 1st week of April, it generated for only 3 days after which it was shutdowndue to condensate problem. From early May to the 3rd week of July, it was unavailabledue to bearing, it failure and lube oil leakage.The unit was synchronized to the grid from 4th week in July to 31st December, 2007. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 18
  • Barge 204 was on the grid between January and 5th April when it was shutdown due tocondensate problem. It was tied back on 12th April and ran till 22nd May when it trippedon high frequency. Between June and December 2007, the unit went on outage thriceviz: 1st to 8th September on maintenance outage; third week of September due to waterleakage from cooling water pump and 26th October to the first week of November due torotating pump problem.AES 205 barge went on outage six times in 2007. Between 22nd and 9th February it wasshutdown to reposition its circuit. From 1st to 22nd March it was unavailable on dieselmain starting problem. In second week of April, it was shutdown due to condensateproblem.From the first week in September to 19th October, a major combustion inspection wascarried out on the unit. By 31st December 2007, the unit was still available andsynchronized to the grid.Barge 207 ran from January to 5th February. It was on planned outage thence till the tailend of February. On the 2nd week of April it had starting problem. Synchronized on 18thApril, it ran till 8th May when it was shutdown 7 weeks for compressor washing. It laterwent on outage from 3rd July to the 2nd week of August on generator fault.The unit was however available thereafter till 31st December, 2007.Barge 208 generated in the first 3 weeks of January, tripped on turbine bearing highvibration and remained out of service till 10th May. It generated thence till 31st Decemberexcept outage in June (15th – 13th); August (1st week maintenance) and November (1stweek due to serious water leakage.Barge 209 was mostly available in 2007. It was shutdown only once in the third week ofMarch due to condensate problem.Barge 210 was available from January to December, 2007 except a week outage in the 2ndweek of April due to condensate problem.Barge 211 was on outage due to transformer fault. It ran till 2nd week in April when itwas shutdown due to condensate problem. From then till 31st December, 2007, the unitproduced energy into the grid.1.28 OKPAI IPPOkpai ST1 was synchronized to the grid from January to 10th April when it went onoutage due to steam leakages. Restored on 29th April, the unit was available till 31stDecember except the first week of June when it tripped on fault and the third week ofDecember when it was shutdown for generator maintenance. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 19
  • TABLE 3. SUMMARY OF GENERATION CAPABILITIES OF PHCN POWER STATIONS AS OPERATED IN THE YEAR 2007( JANUARY - DECEMBER ) AVAILABILIT AVERAGE INSTALLED POWER STATION Y FACTOR AVAILABILIT CAPACITY (MW) (MW) Y (MW) KAINJI HYDRO 0.69 524.14 760.00 JEBBA HYDRO 0.99 572.28 578.40 SHIRORO 0.87 524.80 600.00 EGBIN STEAM 0.56 735.53 1320.00 AJAOKUTA 0.90 80.94 90.00 A.E.S (GAS) 0.81 219.96 270.00 SAPELE ST 0.11 114.59 1020.00 OKPAI GAS/ 0.88 393.88 450.00 AFAM (GAS) 0.37 228.11 623.00 DELTA (GAS) 0.38 338.80 882.00 GEREGU (GAS) 0.60 250.42 414.00 OMOKU GT 0.86 85.67 100.00 OMOTOSHO 0.23 76.79 335.00 OLORUNSOGO 0.03 10.29 335.00 TOTAL 0.53 4156.19 7777.40DEFINITIONS:-1. AVAILABILITY FACTOR = AVERAGE MW. AVAILABILITY PI2. PI = The sum of current site rating of commissioned units installed in the station for the year.3. AVERAGE MW. AVAILABIL = This is a measure of average usable MW capacity of each station putting gas pressure constraints and other external factors into consideration. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 20
  • POWER STATIONS AVERAGE MW AVAILABILITY JANUARY-DECEMBER 2007, CHART 9 (SEE TABLE 3) 800.00 700.00AVERAGE MW AVAILABILITY (MW) 600.00 500.00 400.00 300.00 200.00 100.00 0.00 TA S) S) S) S/ RO S) O M ST O O RO T G R G SH EA A A A A A U YD YD O LE SO IG (G (G (G (G U K TO ST IR K O PE H H PA N M .S TA O SH U JA O RU IN FA A JI M .E EG SA K M EL B IN A O B A O A O LO B EG ER D A JE K O G POWER STATIONS POWER STATIONS INTALLED CAPACITIES JANUARY-DECEMBER 2007, CHART 10 (SEE TABLE3) 1400 1200 INSTALLED CAPACITIES(MW) 1000 800 600 400 200 0 O AF G KA JE SH EG AJ A. SA D O O O EL KP ER M LO E. M B AO AM IN PE IR BI O BA S O TA AI R EG JI O N TO KU LE KU (G U (G RO G H ST H (G N U SH AS TA AS YD AS YD ST SO G AS EA (G T O ) / ) R R G ) AS M O O O ) POWER STATIONS Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 21
  • GT11 was available throughout the year except a five week outage between the 2nd weekof May and 3rd week of June (20th) when the unit was shutdown for overhaul.GT12 was synchronized to the grid from January to 22nd March. It then went oninspection and restored by the end of April 2007. The unit pooled power to the grid till31st December except the last week of September 2007.1.29. AJAOKUTA P.S.Ajaokuta ST1 produced from January to 9th February when it was shutdown for routinemaintenance. It was restored by 17th February but tripped again by 12th March as theH.P. side of the unit. The unit was then available for 10 weeks after which it tripped onaxial shifts problem in the 2nd week of June. It ran in the next 13 weeks and then trippeddue to System Disturbance. The unit generated into the grid in November and December2007, except the last week of November when it was out due to low gas pressure.ST2 was available in the first 3 weeks of January. After a week outage the unit stayed ongrid till the last week of May when it tripped on fault. In the next 13 weeks June to the1st week in September, the unit generated into the grid following which it tripped andremained out of service for 10 days. It barely ran for a week when it developedhydrologic trouble.From October to 31st December, 2007, the unit was unavailable.1.30 OMOKU P.S.Omoku GT1 was available throughout 2007 except 17th to 23rd January when the causesof its tripping could not be ascertained and the last week in May when it was out ofservice on reverse power problem.Omoku GT2 was available through out 2007.Omoku GT3 was available throughout 2007 with exception of the 2nd to 4th week ofJanuary when it tripped on fault.Omoku GT4 was unavailable from January to the 3rd week of March, It then generated tillthe 1st week of May when it was shutdown on planned outage. Restored back by 5th June,the unit was synchronized to the grid. It remained available until the last week ofSeptember when it was on annual maintenance. The unit was still out-of-service by 31stDecember, 2007.1.31 OMOTOSHO P.S.Commissioning of Omotosho GT1 commenced on 23rd June, 2007. 1st July, the unitwas shutdown for continuation of commissioning test. Tied back to the grid by the 3rdweek of July, GT1 generated till 6th August when it developed starting problem for about Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 22
  • a week. On 14th August it could not run due to low gas pressure that spanned 10 days.The unit was however available from 24th August to 31st December, 2007.Omotosho GT3 was commissioned in the first week of December. It tripped on D.C.ground fault but was restored by the 2nd week and remained available by 31st December,2007.Omotosho GT6 commissioning and commenced in mid October. It generated till 21stwhen it tripped due to system disturbance, restored back by the last week of October, itgenerated thereafter till 31st December, 2007.Omotosho GT7 was commissioned tied to the grid on 2nd September 2007. It generatedtill 7th October when it tripped on fault. Tied back in the 2nd week of October, the unitwas synchronized to the grid up till 31st December, 2007.Omotosho GT8 commenced generation by 15th August and was available till 31stDecember, 2007.1.32 GEREGU P. S.GT1 was commissioned on 9th March 2007. It was shutdown by 18th March for checks.Restored on 21st March, the unit ran till 26th June when it was shutdown for gasrestoration. Between 1st to 23rd July, the unit generated into the grid.Thereafter it was on outage due to faulty natural gas unloading valve. From then the unitwas available except 10 days outage on mid September caused by low water pressure andan 11 – day maintenance outage in early December. The unit was howeversynchronously tied to grid by 31st December, 2007.GT1 started production on 5th April, 2007. Its was on a 4 day outage for gas piperestoration on 26th June. From 1st July to August, the unit was tied to the grid.For almost a month of September the unit was on outage due to vent fan oil leakage.It generated on October and November but unavailable through out December on faultycooling system.GT13 came on stream in early June. It was however shutdown in order to restore gaspipe line. Between 7th to 25th July, the unit developed faulty fan motor. From 25th July to28th September it generated into the grid.It then went on a week outage to repair the generator transformer tap changer. The unitwas on the grid throughout December, 2007.1.33 OLORUNSOGO P.S. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 23
  • Commissioning of the units commenced in December, 2007.GT1’s commissioning commenced on 7th. It ran for the rest of December, 2007.GT2’s commissioning began on 17th December, 2007. It was on the grid for the rest ofDecember, 2007.GT3 was commissioned on 10th December, 2007. The unit was still generating by 31stDecember, 2007.GT5 was commissioned on 16th December. It generated for the remaining days ofDecember, 2007.1.40 GENERATION ORDERING AND LOAD DISPATCHAn integrated grid was operated in 2007, pooling generation from Kainji, Jebba andShiroro Hydro Power Station and Egbin, Delta, Afam, Sapele, AES, Okpai, Omotosho,Omoku and Olorunsogo thermal Stations.Inadequate gas supply from the Nigerian Gas Company (NGC) and incessant low gaspressure militated against full thermal capacity generation into the grid. Among theaffected Stations were: Egbin and AES which although capable of an average generationof 955.0MW was frequently confined between 200 and 700 MW.There was a time that the combined stations could only pooled less than 100 MW into thegrid. Likewise, Geregu, Omotosho and Olorunsogo output to the grid was often limitedby gas availability to about 30% of available capacity.Since generation availability was grossly inadequate to meet the ever increasing loaddemand, load shedding continued through out the year in order to maintain powerbalance.1.50 FREQUENCY CONTROLDue to generation shortage, the grid was operated outside the frequency control policy of50Hz + 0.40% i.e. 49.80Hz to 50.20Hz, resulting in frequency excursions outside theoperational limits.Most of the gas turbines on the grid were operated on temperature control mode. Hencethey were often insensitive to vagaries of system frequency.The automatic voltage regulator (AVRs) and governor system of Kainji, Kaplan units(variable blades) were not functional. All the other machines in the system wereconsidered base load, except Jebba units that regulate occasionally. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 24
  • ANNUAL ENERGY GENERATED (GWH) 1973-2007 CHART 11 07 23,187 06 23,300 05 24,077 04 24,132 03 22,612 02 21,544 01 17,637 00 15,227 99 16,291 98 16,253 97 15,416 96 15,971 95 15,793 94 14,557 93 14,617YEAR 92 15,066 91 14,212 90 13,364 89 12,700 88 11,471 87 11,141 86 10,665 85 10,155 84 8,927 83 8,456 82 7,102 81 6,766 80 5,724 79 5,151 78 4,359 77 4,195 76 3,750 75 3,322 74 2,780 73 2,493 0 5000 10000 15000 20000 25000 30000 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 ENERGY(GWH) 24 27 33 37 41 43 51 57 67 71 84 89 10 10 11 11 12 13 14 15 14 14 15 15 15 16 16 15 17 21 22 24 24 23 23 ENERGY GENERATED (GWH) SIMULTANEOUS NATIONAL PEAK (MW) 1973-2007 CHART 12 07 3,600 06 3,682 05 3,774.1 04 3,427.5 03 3,479.3 02 3,223.4 01 2,934.49 00 2,499 99 2,458 98 2,448 97 2,457 96 2,470 95 2,452 94 2,446 93YEAR 2,330 92 2,382 91 2,246 90 2,219 89 2,008 88 1,952 87 1,855 86 1,730 85 1,720 84 1,532 83 1,434 82 1,448 81 1,323 80 1,181 79 1,095 78 887 77 767 76 708 75 579 74 457 73 385 0 500 1000 1500 2000 2500 3000 3500 4000 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 PEAK 385 457 579 708 767 887 109 118 132 144 143 153 172 173 185 195 200 221 224 238 233 244 245 247 245 244 245 249 293 322 347 342 377 368 360 PEAK DEMAND (MW) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 25
  • It is however noteworthy that the underfrequency relays installed in some stationsobviated system collapses on several occasions.1.60 VOLTAGE CONTROLIn 2007, the voltage control policy of 330kV + 5% and – 15% on the 330kV buses and132kV +10% and -15% for the 132kV buses were regularly maintained. The AreaControl Center’s efforts in this regard were commendable.Diverse Engineering techniques of voltages control were applied in the year. Among theapplied techniques were reactive power generation/absorption by generators in theproximity of the controlled bus; use of reactive compensators and as a last resortswitching of 330kv circuits.The last option is seldom applied accepts all else failed as switching out of a circuitwould weaken the system security.Since November, 2001 System supervision through the minored SCADA facilities of thesupplementary National Control Centre was of a tremendous benefit as voltage profile ofthe 330kV buses were conspicuously display on the Man-Machine-Interface (MMI)monitors.1.70 Outage PlanningGeneration and Transmission Outages Plan for 2007 were implemented. The analysis ofeach type of outage follows:1.71 Generation Outage PlanningAs required by the Operational Procedure No. (OPN 10), all Power Stations andTransmission Areas should forward their planned outages schedule for the subsequentyear to National Control Centre (NCC) latest by the November of penultimate year to theplanned outage period.In order to effect this, NCC addressed memos to the Chief Executive Officers in all thePower Stations and Regional Transmission Managers of the Transmission Regions.They were requested to submit their Annual Maintenance Programme to N.C.C. latest by30th November.A properly coordinated master programme for 2007 outages was drawn taken cognizanceof the Grid integrity and security. Compliance with the maintenance programme wasmonitored in the year.1.72 Transmission Outage Planning Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 26
  • TABLE 4 PHCN POWER SYSTEM FREQUENCY CHARTLIST ALLOCATION FREQUENCY REMARKSNO. (HZ) 1 UPPER STATUTORY LIMIT 50.50 2 UPPER OPERATIONAL LIMIT 50.20 3 NORMAL FREQUENCY 50.00 4 LOWER OPERATIONAL LIMIT 49.80 5 LOWER STATUTORY LIMIT 49.50 6 THREE-STAGE UNDERFREQUENCY RELAY LOAD OPERATION:- 1 49.80HZ 2 49.50HZ 3 49.20HZ 7 1ST STAGE GEN. PROTECTION AFAM I GTS 49.00 0.5 SECS. DELAY 8 2ND STAGE GEN.PROTECTION SAPELE GTS. 48.70 1.0 SECS. DELAY 9 3RD STAGE GEN. PROTECTION:- (i) AFAM II & III GAS TURBINES 48.50 INSTANTANEOUS. (ii) AFAM IV GAS TURBINES 48.50 0.15 SECS.DELAY (iii) SAPELE GAS TURBINES. 48.50 1.0 SECS.DELAY (iv) GEREGU UNITS 48.50 20.0 SECS.DELAY (v) AES UNITS 48.50 3.0 SECS.DELAY10 4TH STAGE GEN. PROTECTION: (i) DELTA IV GAS TURBINES 48.00 0.25 SECS.DELAY (ii) OMOTOSHO UNITS 48.00 (iii) OLORUNSOGO UNITS 48.0011 5TH STAGE GEN. PROTECTION: SAPELE STEAM TURBINES 47.50 2.0 SECS.DELAY12 6TH STAGE GEN. PROTECTION: EGBIN ST.UNITS STAGE 1 47.50 0.5 SECS. DELAY [Fast Call Back] STAGE 2 47.00 3.0 SECS.DELAY [House Load]13 7TH STAGE GEN. PROTECTION: OKPAI UNITS 46.95 0.15 SECS.DELAY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 27
  • NCC conducted a power flow study to evaluate the impact of 330kV Transmission and132kV sub transmission circuits, transformers, reactors and switchgears.System integrity, security and stability were highly considered prior to conveyingapproval of the maintenance schedule to each station.1.721 2007 Forced Outage AnalysisThe analysis below was based on the equipment forced outage records kept at NCC,Osogbo.1.722 330KV Circuit Forced OutagesA cumulative value of 330kV forced outages in 2007 was 281. (Table 5A). This was6.02% greater than 299 recorded in year 2006.There were 26 incidents of forced outages in January 2007. It rose to 35 in February.The year’s peak of 42 was attained in September. While the least incidents of 9, wasregistered in April 2007. In the previous year the minimum of 12 forced outages was inJuly, 2006.1.723 132kV Circuit Forced OutagesThe incidents of 132kV circuit forced outages in 2007 were 789. It dropped by 3.87% incomparison with 817 figure of 2006. The 132kV forced outages peaked in Septemberwith a figure of 105, whereas it peaked at 127 in October, 2006. Minimum incidents of132kV forced outages occurred in February as against the minimum of 49 registered inJune and December, 2007. (Tables 6A & 6B).1.724 330kV Planned, Urgent and Emergency OutagesThe incidents of planned, urgent and emergency outages in 2007 were 110, 71 and 48respectively compared with 120, 74 and 43 values of 2006. A comparison of the figuresdepicted drops in planned and urgent outages.Frequency of planned outages dropped by 8.33%: urgent outages reduced by 4.05%whereas emergency outages rose by 10.40% in comparison with 2006 values.1.725 132kV Planned, Urgent and Emergency OutagesIn 2007 the incidents of 132kV planned, urgent and emergency outages aggregated to103, 225 ands 3329 respectively. Relative to 2006, planned outages dropped by 14.63%;urgent dropped by 29.02% while incidents of emergency outages rose by 1.52% (Tables6A & 6B) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 28
  • 2007 OUTAGES STATISTICAL SUMMARY (330KV LINE - TABLE 5A) FORCED FORCED PLANNED PLANNED URGENT URGENT EMERGENCY EMERGENCY MONTH TOTAL TOTAL CUM. OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVE Generation and Transmission Grid Operations-2007-National Control Centre, OsogboJAN. 26 26 12 12 9 9 3 3 50 50FEB. 35 61 6 18 10 19 6 9 57 107MAR. 27 88 19 37 12 31 14 23 72 179APR. 9 97 7 44 9 40 5 28 30 209MAY 31 128 7 51 1 41 3 31 42 251JUN. 15 143 4 55 3 44 4 35 26 277JUL. 17 160 9 64 5 49 4 39 35 312AUG. 17 177 10 74 3 52 2 41 32 344SEP. 42 219 11 85 5 57 2 43 60 404OCT. 28 247 15 100 3 60 3 46 49 453NOV. 23 270 6 106 6 66 2 48 37 490DEC. 11 281 4 110 5 71 0 48 20 510 29 2006 OUTAGES STATISTICAL SUMMARY (330KV LINE - TABLE 5B) FORCED FORCED PLANNED PLANNED URGENT URGENT EMERGENCY EMERGENCY MONTH TOTAL TOTAL CUM. OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVEJAN. 25 25 14 14 9 9 3 3 51 51FEB. 27 52 14 28 4 13 4 7 49 100MAR. 30 82 9 37 7 20 0 7 46 146APR. 30 112 7 44 5 25 2 9 44 190MAY 21 133 4 48 11 36 1 10 37 227JUN. 32 165 9 57 4 40 7 17 52 279JUL. 12 177 4 61 6 46 8 25 30 309AUG. 16 193 9 70 3 49 11 36 39 348SEP. 21 214 15 85 3 52 5 41 44 392OCT. 26 240 11 96 5 57 0 41 42 434NOV. 36 276 15 111 9 66 2 43 62 496DEC. 23 299 9 120 8 74 0 43 40 536
  • 2007 OUTAGES STATISTICAL SUMMARY (132KV LINE - TABLE 6A) FORCED FORCED PLANNED PLANNED URGENT URGENT EMERGENCY EMERGENCY MONTH TOTAL TOTAL CUM. OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVEJAN. 52 52 5 5 21 21 200 200 278 278 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboFEB. 33 85 7 12 15 36 350 550 405 683MAR. 40 125 13 25 17 53 250 800 320 1003APR. 48 173 3 28 18 71 149 949 218 1221MAY 101 274 8 36 24 95 228 1177 361 1582JUN. 71 345 9 45 10 105 362 1539 452 2034JUL. 85 430 12 57 32 137 490 2029 619 2653AUG. 56 486 9 66 26 163 295 2324 386 3039SEP. 105 591 4 70 19 182 106 2430 234 3273OCT. 93 684 3 73 31 213 376 2806 503 3776NOV. 58 742 20 93 25 238 278 3084 381 4157 30DEC. 47 789 10 103 17 255 245 3329 319 4476 2006 OUTAGES STATISTICAL SUMMARY (132KV LINE - TABLE 6B) FORCED FORCED PLANNED PLANNED URGENT URGENT EMERGENCY EMERGENCY MONTH TOTAL TOTAL CUM. OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVE OUTAGE CUMULATIVEJAN. 54 54 12 12 21 21 143 143 230 230FEB. 63 117 10 22 24 45 267 410 364 594MAR. 79 196 15 37 34 79 299 709 427 1021APR. 63 259 13 50 17 96 379 1088 472 1493MAY 92 351 12 62 21 117 417 1505 542 2035JUN. 52 403 7 69 29 146 493 1998 581 2616JUL. 49 452 14 83 23 169 499 2497 585 3201AUG. 52 504 6 89 18 187 339 2836 415 3616SEP. 78 582 13 102 33 220 97 2933 221 3837OCT. 127 709 10 112 41 261 49 2982 227 4064NOV. 59 768 8 120 37 298 139 3121 243 4307DEC. 49 817 3 123 19 317 158 3279 229 4536
  • 1.726 Combined 330kV and 132kV OutagesFrequency of occurrence of 330kV outages comprising forced, planned, urgent andemergency outages in year 2007 was 510. This was lower than 2006 value of 536 by 26(4.85%)In 2007 combined incidents of 132kV outages was 4476. It was 1.32% smaller than 2006value of 4536.A unified 330kV network was operated in 2007 unlike year 2002, 2003 and 2004 whenthe grid was split into islands A1 and A2.1.80 ENERGY PRODUCTIONThe energy generated from all the Power Holding Company of Nigeria (PHCN) ownedPower Stations was 17215055.11 MWH.This figure was lower (2.80%) than that of 2006.The Independent Power Producers (IPPs) which included AES, Okpai, Ajaokuta andOmoku (P/H) all together pooled 5971487.81 MWH (See Table 7-10)In 2007, these IPPs increased their energy generation by 6.82% when compared with2006 figure. The Nigerian Electricity Supply Corporation Limited (NESCO) andOmoku were separately feeding isolated portion of grid on 33kV network NESCO alonesupplied 126788.42 MWH throughout 2007. The energy generated by NESCO alsoincreased by 7.65% when compared with 2006 figure. During the year, two new ThermalPower Stations were connected to the grid – Geregu and Omotosho.Olorunsogo Power Station test ran their units in December 2007.The total energy generated by the PHCN owned Power Stations and the IPPs excludingNESCO was 23186542.92 MWH.The Hydro Power contribution was 7776409.7 MWH (33.54%) while the Thermal PowerPlants produced 15410133.22 MWH (66.46%) (See Table 8.0). The hydro powercontribution was higher than the figure of energy generated by the Hydro Power Stationsin 2006 by 805306.22 MWH (11.55%).This boost was accomplished by the robust inflow flood yield witnessed by Kainji andJebba reservoirs during the white flood.The availability of the power plants in the hydro stations helped to utilise the copiousflood yield for power generation, hence no water was spilled in any of the lakes, during Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 31
  • 330KV FORCED OUTAGES (2006 & 2007) CHART 13 (TABLES 5A & 5B) 350 CUMMULATIVE FREQUENCY OF OUTAGES 300 250 200 150 100 50 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006MONTHLY 2007MONTHLY 2006CUM 2007CUM 132KV FORCED OUTAGES (2006 & 2007) CHART 14 (TABLES 6A & 6B) 900 800CUMMULATIVE FREQUENCY OF OUTAGES 700 600 500 400 300 200 100 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006MONTHLY 2007MONTHLY 2006CUM 2007CUM Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 32
  • COMBINED 2006 & 2007 330KV OUTAGES CHART 15 (TABLES 5A & 5B) 600 CUMMULATIVE FREQUENCY OF OUTAGES 500 400 300 200 100 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006MONTHLY 2007MONTHLY COMBINED 2006 & 2007 132KV OUTAGES CHART 16 (TABLES 5A & 5B) 5000 4500CUMULATIVE FREQUENCY OF OUTAGES 4000 3500 3000 2500 2000 1500 1000 500 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006MONTHLY 2007MONTHLY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 33
  • 330KV PLANNED, URGENT & EMERGENCY OUTAGES (2006 & 2007) 140 CHART 17 (TABLES 5A & 5B) 120CUMULATIVE FREQUENCY OF 100 OUTAGES 80 60 40 20 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006 PLAN CUM 2007 PLAN CUM 2006 URGENT CUM 2007 URGENT CUM 2006 EMERGENCY CUM 2007 EMERGENCY CUM 132KV PLANNED, URGENT & EMERGENCY OUTAGES ( 2006 & 2007) 3500 CHART 18 (TABLES 5A & 5B) 3000 CUMULATIVE FREQUENCY OF OUTAGES 2500 2000 1500 1000 500 0 JAN. FEB. MAR. APR. MAY JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS 2006 PLAN CUM 2007 PLAN CUM 2006 URGENT CUM 2007 URGENT CUM 2006 EMERGENCY CUM 2007 EMERGENCY CUM Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 34
  • white flood. Shiroro energy generated was lower than the figure of 2006, because theinflow yield was low; hence much water was not stored to fill the lake.However the thermal plants contribution fell below 2006 record by 918243.57 MWH(5.62%)The shortfall in the thermal generation was as a result of many issues:(a) Unstable dry gas supply from the Nigerian Gas Company (NGC)(b) When Transmission lines carrying the generation output tripped, the machines were tripped as well. It took days for such machine to come back to the grid.(c) After System collapses (partial or total) the thermal power plants never came back quickly especially the steam turbines.(d) Unavailable transmission lines.For two consecutive years, 2006 and 2007 the generation output from Egbin P.S, thelargest Power Station in the grid has been on the decline.In 2007, Egbin generation was 73.85% of what it generated in 2006.During the month of April, 2007 Egbin P. S. ran one unit on high power fuel oil (HPFO)consuming about 5134.97 Metric Tones (MT).Also in July similar operation consumed about 1935.61 Metric Tones (MT).The simultaneous National Peak Generation for 2007 was 3599.6MW and it was attainedon 11th Jan, 2007 at 2200 hrs. (See Table 15 & 16) This should not have been the periodof Peak Generation, which was expected during the months of March and April.All the Power Stations consumed a total of 930788.10MWH in 2007.In the months of August 2007 the Power Stations’ consumption was very high. Thefigure was bloated because the Ajaokuta Steel Complex operated the Rolling Mills.(Table 8-10) Most of their consumption was not on the auxiliaries. That in turn showedup as apparent losses.The net energy sent out to the various injection substations, via the Transmission lineswas 22255754.83 MWH.Total energy made available for sales and Distribution losses by the end of 2007 was20419068.68 MWH. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 35
  • This represented 91.75% of the total energy sent out. The overall transmission losses andsubstation consumption amounted to 8.25% of the total energy sent out.1.8.1 Energy Sales AnalysisDuring the year precisely April, 2007 the Transmission Company of Nigeria (TCN)carved out two Transmission Regions namely Osogbo and Port-Harcourt out of Lagosand Enugu Regions respectively; bringing the total number of Transmission Regions toeight (8).In Table 10 and 11 the total Energy made available for sales and Distribution lossesamong the eight Transmission Regions of PHCN were shown.(a) Lagos Region (Akangba, Ikeja West) Area Transmission 7714483.46 MWH Injection points (37%)(b) Enugu Region (New Haven, Onitsha Area Transmission 3077766.55 MWH Injection points (15%)(c) Osogbo Region (Osogbo and Ayede Area Transmission) 569705.55 MWH Injection points (3%)(d) Port- Harcourt Region (Alaoji area Transmission ) 567680.44 MWH Injection points (3%)(e) Kaduna Region (Kaduna and Kano Area Transmission) 2140837.20 MWH (10%)(f) Shiroro Region (Shiroro, Birnin Kebbi, Jebba & Katampe 2869972.88 MWH Area Transmission) (14%)(j) Bauchi Region Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 36
  • (Gombe and Jos Area Transmission) 1128970.40 MWH (6%)(h) Benin Region (Benin, Ajaokuta and Alaoji AreaTransmission) 2349652.00 MWH (12%)Comparing the Regional Consumption of 2007 and 2006, it was clear that Lagos Regionconsumed only 91.53% of what it did consume in 2006. This represented 37% of theoverall total energy made available for sales. The shortfall was due to the fact that itsproximity to National Control Centre, its feeders were always used for frequency Controlon emergencies.Kaduna Region lost some energy when the sub-station at (Kano) Kumbotso lost its150MVA 330/132kV transformer. Shiroro Region lost about 3.75% of what it consumedin 2006.Most of the losses in some Regions were picked up in other regions such as Enugu, Beninand Bauchi, because of inadequate generation.In all, the total energy made available for sales including distribution losses in 2007 fellby 2.88%, when compared with the figure of 2006.1.8.2. THERMAL STATIONS GAS SUPPLYPHCN is a major consumer of abundant natural gas marketed by Nigerian Gas Company(NGC). All the PHCN owned Thermal Power Stations namely Egbin, Sapele, Delta andAfam; also AES and Okpai IPP ran primarily on natural gas. During the period ofdroughts or low lake levels PHCN depended solely on the gas supply from NGC. Overthe years, the quantity and quality of supply of this commodity had not been adequate forPHCN Operations. The few consequences of this inadequate supply were:1. Inability of PHCN to utilize available thermal plants capacity for power generation.2. Plants breakdowns due to ingress of condensate in the Combustion chamber or incessant forced outage.3. Frequent system disturbances.4. Embarrassment to PHCN corporate image in particular and the country at large.5. Loss of revenue to PHCN and economic activities throughout the country.6. Environmental pollution as some customers put on their Personal generators in the absence of PHCN supply. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 37
  • TABLE 7: ENERGY GENERATED (MWH) JAN - DEC. 2007 TOTAL CALAB TOTAL AJAOKU IPPMONTHS KAINJI JEBBA SHIRORO EGBIN SAPELE DELTA AFAM OMOTOSHO GEREGU AES OKPAI OMOKU NESCO (PHCN+IPP AR (PHCN) TA TOTAL ) JAN. 226974.00 244165.00 255007.00 423493.49 38575.00 321061.00 89691.00 1598966.49 179136.55 282885.00 40126.00 15246.52 517394.07 10910.92 2116360.56 FEB. 186810.00 213105.00 193805.00 347511.09 34399.00 251577.40 35653.70 1075.00 1263936.19 139278.34 266845.00 37198.00 20068.82 463390.16 8814.36 1727326.35 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo MAR. 299805.00 223989.00 137458.00 181102.39 40505.00 250188.00 33920.20 54270.80 1221238.39 81225.51 233314.00 40920.00 36543.46 392002.97 9088.75 1613241.36 APR. 299348.00 270807.00 85769.00 323920.75 39490.00 213153.00 68021.50 128575.60 1429084.85 113989.40 129863.00 47894.00 55540.70 347287.10 9233.54 1776371.95 MAY 248057.00 235875.00 103974.00 398551.01 33236.00 218094.00 169186.50 155914.18 1562887.69 150047.75 233532.00 43512.00 26364.10 453455.85 10538.17 2016343.54 JUN. 120051.40 108520.00 131566.00 365563.00 43647.00 217190.90 133737.20 150131.00 1270406.50 136561.53 201260.00 38215.00 38487.37 414523.90 10347.64 1684930.40JAN.-JUN 1381045.40 1296461.00 907579.00 2040141.73 229852.00 1471264.30 530210.10 0.00 489966.58 0.00 8346520.11 800239.08 1347699.00 247865.00 192250.97 2588054.05 58933.38 10934574.16 TOTAL JUL. 86015.30 78393.00 210884.00 298869.72 46042.00 220961.00 142542.60 16256.11 127594.90 1227558.63 127108.31 338545.00 37907.00 51651.97 555212.28 11806.98 1782770.91 38 AUG. 168660.00 189538.00 240737.00 301618.65 73015.00 208163.70 132726.10 32757.80 208163.70 1555379.95 173022.81 339311.00 250013.00 64485.02 826831.83 11534.55 2382211.78 SEP. 247023.00 360842.00 285867.00 287521.37 50903.00 201932.00 128360.40 16298.40 85535.60 1664282.77 154048.78 289475.00 16888.00 36311.30 496723.08 11544.00 2161005.85 OCT. 305307.00 346999.00 229805.00 194983.85 21337.00 219526.40 21737.00 15000.10 101539.00 1456234.35 80842.70 322477.00 182.00 38324.80 441826.50 11352.24 1898060.85 NOV. 296300.00 229622.00 220849.00 225899.00 20297.00 194787.70 142761.60 25249.80 75874.60 1431640.70 195851.00 326398.00 10976.00 20691.47 553916.47 10686.01 1985557.17 DEC. 332399.00 227044.00 135040.00 287646.00 49344.00 180083.50 175764.90 41238.70 104878.50 1533438.60 144383.60 330302.00 8686.00 25552.00 508923.60 10931.26 2042362.20JUL.-DEC 1435704.30 1432438.00 1323182.00 1596538.59 260938.00 1225454.30 743892.60 146800.91 703586.30 0.00 8868535.00 875257.20 1946508.00 324652.00 237016.56 3383433.76 67855.04 12251968.76 TOTALANNUAL 2816749.70 2728899.00 2230761.00 3636680.32 490790.00 2696718.60 1274102.70 146800.91 1193552.88 0.00 17215055.11 1675496.28 3294207.00 572517.00 429267.53 5971487.81 126788.42 23186542.92 TOTAL *.* GRAND TOTAL DOES NOT INCLUDE NESCO WHICH FEEDS ON ISOLATED DISTRIBUTION LOAD
  • TABLE 8: ENERGY GENERATED (MWH) JAN - DEC. 2007 HYDRO HYDRO THERMAL THERMAL TOTAL HYDRO THERMAL TOTAL ENERGY TOTAL ENERGY ENERGY ENERGY ENERGY ENERGY ENERGY ENERGY ENERGY SENT GENERATED SENT OUT GENERATED USED IN GENERATED USED IN USED IN SENT OUT OUTMONTHS STATION STATION STATIONJAN. 726146.00 1995.24 1390214.56 62902.05 64897.29 724150.76 1327312.51 2116360.56 2051463.27FEB. 593720.00 1871.13 1133606.35 52309.59 54180.72 591848.87 1081296.76 1727326.35 1673145.63 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboMAR. 661252.00 2151.24 951989.36 49474.70 51625.94 659100.76 902514.66 1613241.36 1561615.42APR. 655924.00 1984.75 1120447.95 53049.07 55033.82 653939.25 1067398.88 1776371.95 1721338.13MAY. 587906.00 2318.20 1428437.54 75275.67 77593.87 585587.80 1353161.87 2016343.54 1938749.67JUN. 360137.40 1969.26 1324793.00 67300.74 69270.00 358168.14 1257492.26 1684930.40 1615660.40JAN-JUNTOTAL 3585085.40 12289.82 7349488.76 360311.82 372601.64 3572795.58 6989176.94 10934574.16 10561972.52JUL. 375292.30 1955.93 1407478.61 64842.97 66798.90 373336.37 1342635.64 1782770.91 1715972.01 39AUG. 598935.00 1947.79 1783276.78 299658.33 301606.12 596987.21 1483618.45 2382211.78 2080605.66SEP. 893732.00 2011.34 1267273.85 57649.24 59660.58 891720.66 1209624.61 2161005.85 2101345.27OCT. 882111.00 2095.62 1015949.85 33467.09 35562.71 880015.38 982482.76 1898060.85 1862498.14NOV. 746771.00 2045.67 1238786.17 45284.66 47330.33 744725.33 1193501.51 1985557.17 1938226.84DEC. 694483.00 2013.76 1347879.20 45214.05 47227.81 692469.24 1302665.15 2042362.20 1995134.39JUL-DECTOTAL 4191324.30 12070.11 8060644.46 546116.34 558186.45 4179254.19 7514528.12 12251968.76 11693782.31ANNUALTOTAL 7776409.70 24359.93 15410133.22 906428.16 930788.09 7752049.77 14503705.06 23186542.92 22255754.83
  • PERCENTAGE ENERGY USED IN POWER STATIONS JANUARY - DECEMBER 2004/2005 CHART 19 (SEE TABLE 9) 13.00 12.00 11.00 % ENERGY USED IN POWER STATIONS 10.00 9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.00 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS 2006 2007 HYDRO, THERMAL & TOTAL ENERGY GENERATED (MWH) JANUARY - DECEMBER 2007 CHART 20 (SEE TABLE 8)Thousands 2500 2000 1500ENERGY GENERATED(MWH) 1000 500 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS HYDRO ENERGY GENERATED (MWH) THERMAL ENERGY GENERATED (MWH) TOTAL ENERGY GENERATED (MWH) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 40
  • 7. Social Insecurity – Locations, where there was no electricity Evil practices were perpetrated.When two new Power Stations were commissioned, one would expect that PowerGeneration should improve. But the realization was negative.In 2007, the gas supply to the Thermal Power Stations dropped by 12.57%, whencompared with 2006 gas supply. Gas supply pressure was low hence new and oldThermal Plants could not be run. What a stranded investment!Egbin received 70.47% of the quantity of gas it received in 2006. Other Power stationsAES received 83.14%, Delta received 79.10% and Afam received 72.51%. Sapele wasdifferent, in that it was run for only five months in 2006, (August – December).Table 14 showed the overall operating fuel and unit production costs’ profile in 2007.Based on the foregoing, fuel costing analysis, the average thermal fuel cost per unit ofenergy generated in 2007 was 43.50 kobo/unit or 44.57 kobo unit sent out.If 0.0 kobo/unit was assumed for cost of energy production in the hydro stations in 2007,but the overall Hydro/Thermal energy production fuel costs in 2007, stood at 22.33kobo/unit generated or 22.92 kobo/unit of energy sent out.Table 12 shows the total quantity of gas in Million Standard Cubic Feet (mscf) consumedin order to generate in all the thermal stations with exception of Okpai and Omoku PowerStations.The gas consumed by all the thermal stations in 2007 was 87.43% of the quantitysupplied by NGC in 2006.If NGC had supplied this commodity in the right quantity and quality, PHCN would havebeen able to meet electric power needs of her numerous customers who in turn would paytheir bills promptly and PHCN shall reciprocate in settling NGC bills as well.Table 12 shows the quantity of gas consumed by each station in 2007.1.83 GRID ECONOMICSNational Control Center policy of ordering generation on the basis of plant merit ratingswas not again successful in the year 2007.This was mainly due to incessant gas limitations at Egbin/AES, Afam and Delta PowerStations. When gas supply limitations prevailed in the Thermal Power Stations, itbecame necessary to run any available unit with respect to available resources, to reduceload shedding inconveniences around the country. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 41
  • ENERGY GENERATED IN HYDRO P.S. (MWH) JANUARY-DECEMBER 2007 CHART 21 (SEE TABLE 7) 400 Thousands ENERGY GENERATED (MWH) 350 300 250 200 150 100 50 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS KAINJI JEBBA SHIRORO ENERGY GENERATED IN MAJOR THERMAL P.S. (MWH) JANUARY-DECEMBER 2007 CHART 22 (SEE TABLE 7) 450 ThousandsENERGY GENERATED(MWH) 400 350 300 250 200 150 100 50 0 P R V C B L CT N N G AR AY SE JU FE AP NO DE JA JU AU O M M MONTHS EGBIN SAPELE DELTA AFAM OMOTOSHO GEREGU Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 42
  • TABLE 9: ENERGY GENERATION AND POWER CONSUMPTION RECORDS: JAN - DEC 2007 ENERGY ENERGY USED IN GENERATED POWER % ENERGY USED INMONTHS (MWH) STATIONS (MWH) POWER STATIONS 2116360.56 64897.29 3.07JAN. 1727326.35 54180.72 3.14FEB.MAR. 1613241.36 51625.95 3.20 1776371.95 55033.82 3.10APR. 2016343.54 77593.87 3.85MAY.JUN. 1684930.40 69270.00 4.11JAN-JUNTOTAL 10934574.16 372601.65 3.41JUL. 1782770.91 66798.90 3.75AUG. 2382211.78 301606.12 12.66SEP. 2161005.85 59660.58 2.76OCT. 1898060.85 35562.71 1.87NOV. 1985557.17 47330.33 2.38DEC. 2042362.20 47227.81 2.31JUL-DEC 12251968.76 558186.45 4.56TOTALANNUAL 23186542.92 930788.10 4.01TOTAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 43
  • AVAILABLE ENERGY FOR SALES Thousands JANUARY - DECEMBER 2007 CHART 23 (SEE TABLE 10) 2700 2200 1700 1200 ENERGY IN MWH 700 200 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS MWH FOR SALES MWH SENT OUT MWH GENERATED TOTAL MONTHLY ENERGY FOR SALES (MWH) JANUARY-DECEMBER 2006/2007 CHART 24 (SEE TABLE 11) 2500 ThousandsENERGY AVAILABLE FOR 2000 SALES(MWH) 1500 1000 500 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS 2006 2007 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 44
  • Due to the above constraints, the pressure to run the hydro turbines was excessive. Itbecame difficult to strictly follow the planned turbine discharge in all the lakes.The cost of gas supply by the Nigerian Gas Company was computed using a flat tariffrate of thirty naira (N30.00) per 1000 standard cubic feet (mmscf) Tables 12 and 13.The total costs of fuel for Energy production in the Thermal Plants in the year 2007 wasN4,183,552,263.42. (21.03%), below the total cost of natural gas consumed in 2006.Egbin Power Station total generation fuel costs in 2007 was N1,121,443,936.83 or29.53% lower than the total fuel costs in 2006. Similarly the energy produced droppedby 26.15% when compared with the energy produced in the previous year.AES – an Independent Power Plant, (near Egbin) because of the nature of the terms of thepower purchase agreement, the station shared its gas supply with Egbin Power Station.The Power Station was allowed to run all available units, while Egbin P.S. took up theremaining power which the available gas could support.Total cost of Gas used for power production in 2007 was N652,327,833.15 which wasN132,310,785.6 or 16.86% lower than the record of N784,638,618.75 for 2006.Delta Power Station consumed N1,203,815,188.45 worth of fuel gas for its energyproduction in 2007. Like all other Thermal Stations, this figure was N308,321,671.27 or20.39% lower than the previous year fuel cost of production.As expected, the energy produced was 1055335 MWH or 28.13% lower than theprevious year.Afam Power Station total fuel costs in 2007 was N564,938,567.52 which was lower thanthe previous year by N214,131,580.89 or 27.49%.Geregu Power Station which started operation in the month of February 2007 consumed atotal N381,161,645.23 worth of fuel gas for its production.Omotosho also started its operation in August 2007. The cost of gas consumed for itsenergy production was N43,868,649.00 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 45
  • TABLE 10: MONTHLY ENERGY BALANCE SUMMARY JAN. - DEC. 2007 MONTHS ENERGY ENERGY ENERGY TX. LOSSES & TX. LOSSES & SUB. ENERGY AVAILABLE GENERATED SENT OUT AVAILABLE FOR SUB. STN. STN. CONSUMPSION FOR SALES & DIST. (MWH) (MWH) SALES & DIST. CONSUMPSION % OF ENERGY SENT LOSSES % OF ENERGY LOSSES (MWH) (MWH) OUT SENT OUT Generation and Transmission Grid Operations-2007-National Control Centre, OsogboJAN. 2116360.56 2051463.27 1913546.86 137916.41 6.72 93.28FEB. 1727326.35 1673145.63 1531579.61 141566.02 8.46 91.54MAR. 1613241.36 1561615.41 1458962.67 102652.74 6.57 93.43APR. 1776371.95 1721338.13 1606579.52 114758.61 6.67 93.33MAY. 2016343.54 1938749.68 1794011.56 144738.12 7.47 92.53JUN. 1684930.40 1615660.40 1460159.02 155501.38 9.62 90.38 10934574.16 10561972.52 9764839.24 797133.28 7.55 92.45 46JAN-JUN TOTALJUL. 1782770.91 1715972.01 1557719.23 158252.78 9.22 90.78AUG. 2382211.78 2080605.66 1833670.83 246934.83 11.87 88.13SEP. 2161005.85 2101345.27 1917353.29 183991.98 8.76 91.24OCT. 1898060.85 1862498.14 1715416.79 147081.35 7.90 92.10NOV. 1985557.17 1938226.84 1752686.11 185540.73 9.57 90.43DEC. 2042362.20 1995134.39 1877383.19 117751.20 5.90 94.10 JUL-DEC 12251968.76 11693782.31 10654229.44 1039552.87 8.89 91.11 TOTAL ANNUAL 23186542.92 22255754.83 20419068.68 1836686.15 8.25 91.75 TOTAL
  • TABLE 11: ENERGY AVAILABLE FOR SALES PLUS DISTRIBUTION LOSSES IN EACH REGION (MWH) JAN - DECEMBER 2007 P/HARCOREGION LAGOS ENUGU OSOGBO URT KADUNA SHIRORO BAUCHI BENIN TOTALJAN. 788169.73 329804.12 0.00 0.00 224138.11 247305.50 114705.30 209424.10 1913546.86 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboFEB. 624449.87 264760.53 0.00 0.00 176277.71 229292.90 81955.40 154843.20 1531579.61MAR. 558873.72 237079.92 0.00 0.00 174921.73 244511.50 71118.40 172457.40 1458962.67APR. 645753.90 279258.53 0.00 0.00 178100.59 230581.40 91091.90 181793.20 1606579.52MAY. 730178.59 313831.35 0.00 0.00 197087.84 252225.28 102874.80 197813.70 1794011.56JUN. 564791.14 258465.88 0.00 0.00 170466.90 212472.10 84387.70 169575.30 1460159.02JAN-APRIL 3912216.95 1683200.33 0.00 0.00 1120992.88 1416388.68 546133.50 1085906.90 9764839.24 47JUL. 604783.47 260502.36 0.00 0.00 160035.58 229764.55 101689.80 200943.47 1557719.23AUG. 761866.21 345089.92 0.00 0.00 175503.13 234590.62 116092.60 200528.35 1833670.83SEP. 807891.30 353073.24 0.00 0.00 164557.70 261879.22 135911.60 194040.23 1917353.29OCT. 503829.15 145268.80 184082.46 195249.50 161641.07 237780.21 87770.00 199795.60 1715416.79NOV. 559752.29 140633.00 182304.92 177460.50 165617.36 246875.60 70485.60 209556.84 1752686.11DEC. 564144.09 149998.90 203318.17 194970.44 192489.48 242694.00 70887.30 258880.81 1877383.19JUL-DECTOTAL 3802266.51 1394566.22 569705.55 567680.44 1019844.32 1453584.20 582836.90 1263745.30 10654229.44ANNUALTOTAL 7714483.46 3077766.55 569705.55 567680.44 2140837.20 2869972.88 1128970.40 2349652.20 20419068.68
  • TABLE 12 QUANTITY OF GAS CONSUMED (MSCF) FOR THE YEAR 2007MONTH EGBIN AES SAPELE DELTA AFAM GEREGU OMOTOSHO TOTAL JAN 4325.402950 2276.993700 530.878567 4294.096189 1149.131824 NO GENERATION NO GENERATION 12576.503230 FEB 3389.084171 1722.680100 505.037719 3432.726245 443.599432 45.289912 NO GENERATION 9538.417579 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboMAR 1825.534520 1063.906800 591.846320 3466.235308 470.255468 627.897295 NO GENERATION 8045.675711 APR 3032.297103 1430.332200 589.056066 3022.545044 992.921562 1500.072906 NO GENERATION 10567.224881 MAY 3880.167317 1953.017400 684.999724 3139.152393 2003.245524 167.449156 NO GENERATION 11828.031514 JUN 3356.764183 1789.494100 629.137791 3134.126195 1591.541642 1601.169710 NO GENERATION 12102.233621 JUL 2865.089851 1634.320700 716.613299 3226.104529 1718.585438 1389.191985 NO GENERATION 11549.905802 48 AUG 2904.367648 2256.097100 1099.039387 2964.837978 1599.022241 1338.416286 318.391243 12480.171883 SEP 2974.295677 1752.543500 705.250645 2880.269985 1603.994740 983.063222 185.665077 11085.082847 OCT 1922.124090 1041.525700 504.602222 3176.158166 1846.803297 1053.654441 157.507737 9702.375652 NOV 2379.219793 1881.959500 295.108403 2889.408938 2355.280489 795.798064 278.708615 10875.483802 DEC 2747.047517 1905.949300 545.980119 2590.694218 2160.176042 1091.324307 452.382852 11493.554356TOTAL 35601.394820 20708.820100 7397.550262 38216.355189 17934.557699 10593.327284 1392.655524 131844.660878
  • TABLE 13 COST OF GAS ( NAIRA) AGAINST ENERGY ENERATED 2007 MONTH EGBIN AES SAPELE DELTA AFAM GEREGU OMOTOSHO TOTAL JANUARY 136,250,192.93 71,725,301.55 16,722,674.86 135,264,029.96 36,197,652.46 NIL NIL 396,159,851.76FEBRUARY 106,756,151.39 54,264,423.15 15,908,688.15 108,130,876.73 13,973,382.10 1,426,632.23 NIL 300,460,153.74 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo MARCH 57,504,337.38 33,513,064.20 18,643,159.08 109,186,412.21 14,813,047.24 19,778,764.79 NIL 253,438,784.90 APRIL 95,517,358.74 45,055,464.30 18,555,266.08 95,210,168.90 31,277,029.19 47,252,296.54 NIL 332,867,583.75 MAY 122,225,270.49 61,520,048.10 21,577,491.31 98,883,300.38 63,102,234.00 52,746,484.20 NIL 420,054,828.47 JUNE 105,738,071.76 56,369,064.15 19,817,840.42 98,724,975.13 50,133,561.73 50,436,845.87 NIL 381,220,359.06 JULY 90,250,330.31 51,481,102.05 22,573,318.92 101,622,292.67 54,135,441.29 43,759,547.53 NIL 363,822,032.77 49 AUGUST 91,487,580.91 71,067,058.65 34,619,740.69 93,392,396.29 50,369,200.59 42,160,113.01 10,029,324.15 393,125,414.30SEPTEMBER 93,690,313.83 55,205,120.25 22,215,395.32 90,728,504.53 50,525,834.32 30,966,491.49 5,848,449.94 349,180,109.67OCTOBER 60,546,908.84 32,808,059.55 15,894,969.99 100,048,982.22 58,174,303.86 33,190,114.89 4,961,493.70 305,624,833.05NOVEMBER 74,945,423.48 59,281,724.25 9,295,914.69 91,016,381.56 74,191,335.40 25,067,639.02 8,779,321.36 342,577,739.76DECEMBER 86,531,996.79 60,037,402.95 171,983.74 81,606,867.87 68,045,545.33 34,376,715.67 14,250,059.85 345,020,572.19 TOTAL 1,121,443,936.83 652,327,833.15 215,996,443.24 1,203,815,188.45 564,938,567.52 381,161,645.23 43,868,649.00 4,183,552,263.42AVERAGE 93,453,661.40 54,360,652.76 17,999,703.60 100,317,932.37 47,078,213.96 34,651,058.66 8,773,729.80 348,629,355.28
  • TABLE 14 OPERATING FUEL COST (NAIRA/KWh) JANUARY-DECEMBER 2007 MONTHLY TOT.MONTHLY EGBIN AES SAPELE DELTA AFAM GEREGU OMOTOSHO THERMAL HYD/ THERMAL OPT. COST PROD. COSTMONTHS COST/UNIT COST/UNIT COST/UNIT COST/UNIT COST/UNIT COST/UNIT COST/UNIT COST/UNIT COST/UNIT GENER SENT GENERAT SENT GENERA SENT GENER SENT GENER SENT GENERA SENT GENER SENT GENER SENT GENERA SENT ATED OUT ED OUT TED OUT ATED OUT ATED OUT TED OUT ATED OUT ATED OUT TED OUT Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo JAN 0.3217 0.3429 0.4004 0.4135 0.4335 0.4672 0.4213 0.4326 0.4036 0.4057 NIL NIL NIL NIL 0.3961 0.4124 0.2228 0.2286 FEB 0.3072 0.3272 0.3896 0.4042 0.4625 0.5083 0.4298 0.4368 0.3919 0.3962 1.3271 1.3681 NIL NIL 0.5514 0.5735 0.2141 0.2197 MAR 0.3175 0.3453 0.4126 0.4292 0.4603 0.5039 0.4364 0.4485 0.4367 0.4414 0.3644 0.3757 NIL NIL 0.4047 0.4240 0.1946 0.1995 APR 0.2949 0.3147 0.3953 0.4090 0.4699 0.5109 0.4467 0.4590 0.4598 0.4623 0.3675 0.3789 NIL NIL 0.4057 0.4225 0.2157 0.2214 MAY 0.3067 0.3251 0.4100 0.4256 0.6492 0.6881 0.4534 0.4933 0.3730 0.3742 0.3383 0.3418 NIL NIL 0.4218 0.4414 0.2452 0.2529 50 JUN 0.2892 0.3070 0.4128 0.4451 0.4540 0.4853 0.4546 0.4740 0.3749 0.3763 0.3360 0.3393 NIL NIL 0.3869 0.4045 0.2710 0.2803 JUL 0.3020 0.3233 0.4050 0.4185 0.4903 0.5311 0.4599 0.4902 0.3798 0.3812 0.3430 0.3463 NIL NIL 0.3967 0.4151 0.2718 0.2812 AUG 0.3033 0.3247 0.4107 0.4239 0.4741 0.5113 0.4486 0.4565 0.3795 0.3810 0.2025 0.2061 0.3062 0.3127 0.3607 0.3737 0.2275 0.2329 SEP 0.3259 0.3512 0.3584 0.3700 0.4364 0.4795 0.4493 0.4587 0.3936 0.3953 0.3620 0.3648 0.3588 0.3675 0.3835 0.3982 0.1920 0.1961 OCT 0.3105 0.3349 0.4058 0.4185 0.7449 0.8318 0.4557 0.4636 2.6763 2.9818 0.3269 0.3288 0.3308 0.3366 0.7501 0.8137 0.1988 0.2025 NOV 0.3318 0.3553 0.3027 0.3107 0.4580 0.5055 0.4673 0.4794 0.5197 0.5219 0.3304 0.3324 0.3477 0.3523 0.3939 0.4082 0.2105 0.2145 DEC 0.3008 0.3214 0.4158 0.4282 0.3485 0.3865 0.4532 0.4678 0.3871 0.3887 0.3278 0.3304 0.3456 0.3494 0.3684 0.3818 0.2158 0.2207AVERAGE 0.3093 0.3311 0.3933 0.4080 0.4901 0.5341 0.4480 0.4634 0.5980 0.6255 0.4205 0.4284 0.3378 0.3437 0.4350 0.4557 0.2233 0.2292
  • TRANSMISSION REGIONS MONTHLY ENERGY FOR SALES (MWH) JANUARY-DECEMBER 2007, CHART 25 (SEE TABLE 11) 900,000ENERGY AVAILABLE FOR SALES (MWH) 800,000 700,000 600,000 500,000 400,000 300,000 200,000 100,000 0 JAN. FEB. MAR. APR. MAY. JUN. JUL. AUG. SEP. OCT. NOV. DEC. LAGOS MONTHS ENUGU OSOGBO P/HARCOURT KADUNA SHIRORO BAUCHI BENIN REGIONAL ENERGY FOR SALES (MW) JANUARY-DECEMBER 2007, CHART26(TABLE 11) 12% 2349652.20 6% 1128970.40 37% 7714483.46 14% 2869972.88 10% 2140837.20 3% 15% 567680.44 3% 3077766.55 569705.55 LAGOS ENUGU OSOGBO P/HARCOURT KADUNA SHIRORO BAUCHI BENIN Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 51
  • MAJOR THERMAL STATIONS FUEL COSTS. CHART 27 (SEE TABLE 13) 160 140 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 120COSTS IN NAIRA (MILLIONS) 100 80 52 60 40 20 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS EGBIN AES SAPELE DELTA AFAM GEREGU OMOTOSHO
  • MONTHLY UNIT PROD.COST (NAIRA/UNIT) CHART 28 (SEE TABLE 14) 0.9 0.8 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboUNIT PRODUCTION COST (NAIRA/UNIT). 0.7 0.6 0.5 0.4 53 0.3 0.2 0.1 0.0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS THMAL GEN. COST THMAL SENT OUT COST THMAL & HYGEN. COST THMAL & HYD SENT OUT COST
  • STATIONS AVE. PROD.COSTS (NAIRA/UNIT) CHART 29 (SEE TABLE 14) 0.7 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 0.6UNIT PRODUCTION COSTS (NAIRA/UNIT) 0.5 0.4 54 0.3 0.2 0.1 0 EGB IN AES SAP ELE DEL TA AFA M EG U TOS HO GER OMO POWER STATIONS
  • 2.0. CONSTRAINTS TO GRID OPERATIONST his subject is treated under the following sub-headings: • 2.10 System Control Constraints • 2.20 Generation Constraints. • 2.30 Transmission Constraints2.10 Constraints to Grid Operation vis-à-vis System Communications(a) Telecommunication is the LIVEWIRE of Power System Operations and Control. Itis required for:(i) Fast operational information dispatch by the System Operators through the use of reliable privately owned telephone network e.g. PAX independent of public communication outfit such as NITEL.(ii) Supervision and Control of Power-flow with the aid of telemetry, tele-indication and command signals (SCADA).(i) Transmission of official information on the status of the power system to the Management for quick decision making through a network of computers all interconnected by the satellite (VSAT)(ii) Desired fast and discriminative tripping of switchgears – like circuit breakers in Case of severe power system disturbance. (TELEPROTECTION).(iv) It serves as a vital tool used in restoration of power supply in case of total or partial system collapse.Lack of adequate and functional telecommunication facilities often result in:i Elongated restoration time in case of system collapse.ii. Equipment outage duration will be prolonged after it has been released by the National Control Centre on requestiii. The customers of the Power Holding Company of Nigeria will be dissatisfied.iv. There would be loss of revenue for the company.v. Personnel safety is impaired.b ACHIEVEMENTS COMMUNICATIONSSome years past (2006) there were many problems in the system communication thatposed as constraints to Power System Operations and Control. Management consideredseparation of functions in the office of Assistant General Manager (Comms.) in order to Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 55
  • facilitate system communication maintenance. Thus an Assistant General Manager(Comm. Mtce) was appointed to be solely responsible for maintenance of systemcommunication throughout the GRID. Since the creation of that office and thatappointment following are the glaring achievements so far made. Essentially morereliable and dependable communication was provided for efficient operations and controlof the GRID. The feats performed to realize this include:i. Restoration of damaged SOPHO PAX at New Haven T.S. as a result of fire Hazard in the station.ii Restoration of damaged SOPHO PAX at Benin T.S. as a result of thunder Strike.iii. Restoration of Optic Fibre line between Osogbo and Jebba and between Oshogbo and Benin which was out for quite a long time due to VANDALISATION of the 330KV Transmission lines SKYWIRE bearing the Optic Fibre cable.iv. Due to faulty, obsolete ECS-F exchange at Shiroro T.S. (PAX gateway to the North of the GRID) communication to stations like Kaduna, Jos, Kano and Gombe were hindered making operations of the system very difficult. To alleviate the problems this created for the National Control Centre following efforts were successfully carried out.i. Restoration of voice communication on PAX to Shiroro Generation Station by making the station a remote subscriber (on extension 374) to Jebba T.S. SHOPHO Exchange.ii. Configuration of a Trunk Line using available PLC Carrier Link F3 type ETL 580 (back to back arrangement at Shiroro T.S) and configuration of the SOPHO Exchange at both Kaduna T.S. and Jebba T.S. ends.iii. Reactivation of old PLC link type ETC formerly carrying PLS (Party Line System) signal and now converted to convey PAX signal between Jebba and Kaduna thus providing a second outlet for NCC, Osogbo to communicate with Kaduna, Jos and Kano 330KV Transmitting Stations.iv. Participation in installation of new wave traps in the system with higher frequency bandwidth to accommodate more signals (data) replacing the old, aged ones.v. Participation in the installation of new battery banks and chargers to replace the old non-functioning ones in the system which is essential for operation of the communication system.c. SCADA Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 56
  • i. As a result of vandalisation of the Optic Fibre Cable between Jebba and Osogbo since May 23, 2007, the Man Machine Interface System at the National Control Centre was rendered inoperative. This made the Operators blind to the system thus making it extremely difficult to operate the GRID. This system (the Optic Fibre) was eventually restored on September 10, 2007.ii. Sustenance of the 25no. Remote Terminal Units (RTU) Network in the System. Many stations RTU’s that were disturbed were attended to and restored working ok.ii Sustenance of the process input wiring into the RTU’s.iv. Sustenance of the Master Station SCADA equipment located in Shiroro by liaising with the SNCC SCADA Maintenance Crew in the station.All these achievements listed above have resulted in improved System Operations andControl and its attendant effects.HIGHLIGHTS OF COMMUNICATION/SCADA CHALLENGESSCADAi. RTU: Out of 25no RTU’s being monitored on the MMI at NCC only 13no. are functional. Efforts are being made by the maintenance SCADA Crew both at NCC, Osogbo and SNCC, Shiroro to restore the 12no. not functioning. Not being able to view these 12no. Stations on the MMI is disturbing effective operation of the GRID. Availability of spare electronics SCADA RTU modules and shortage of fund are big constraints in this case.ii. Another problem being encountered on the MMI is unidentified object positions on some of the RTU’s. This also is being looked into. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 57
  • COMMUNICATIONSi.. Restoration of voice communication to: a. Birnin Kebbi 330KV T.S. b. Aja 330KV T.S. c. Gombe 330KV T.S.ii. Restoration of Optic Fibre Voice Communication to: a Benin 330KV T.S. b. Sapele P.S. c. Delta P.S. d. Egbin P.S. e. Akangba T.S. f. Ikeja West T.S.All these are out as a result of the Sky wires bearing the Optic Fibre cables in thedifferent directions that were vandalized. Management has been informed and action ison to restore them. g. Kainji P.S.This is a module problem and effort is being made to repair and restore the line.iii. Upgrade of SOPHO PAX from version 205 to version 810 for improved performance in stations like: a. Onitsha T.S b. New Haven T.S. c. Alaoji T.S. d. Kano T.S. e. Gombe T.S. f. Kaduna T.S.The SOPHO exchange version 810 incorporates EPROM – a storage device that is notaffected whenever there is loss of D.C. power supply in the stations.iv. Replacement of obsolete ECS-F exchanges in stations like: a. Afam P.S. b. Kainji P.S. c. Shiroro T.S. and Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 58
  • d. Installing a PAX exchange at Jos 330KV T.S.On these, efforts are going on the procurement of is3030 SOPHO PAX 3000 exchangeespecially for installation at Jos and Shiroro that are strategic to PAX operations towardsthe north of the GRID.v. Transfer of SCADA signals from PLC ETL540 Aiyede-Osogbo link to PLC ETB to restore SCADA RTU for Aiyede T.S. for viewing at NCC on the MMI.vi. Replacement of old ETB PLC Links.It is the obsolete; over twenty-one years old ETB/ETC PLC links that are still in use inthe following stations: a. Jos – Gombe b Kaduna – Jos c Kaduna – Kano d. Kainji – Birnin Kebbi e. Onitsha – New Haven f. Benin – Ajaokuta g Benin – Ikeja West.These links are old and erratic in operation. They are also limited in channels and hencein signal handling capability. This is posing great constraint to the transmission of voiceand other telecommunication signals from such stations to others in the system especiallyNational Control Centre.However, some of these problems will be over by the time the on-going World Banktelecommunication projects by SIEMENS are completed in which new PLC typePowerlink and Microwave Radio links are being installed. The project includes PLCinstallation in 132KV stations throughout the GRID.vii. Extension of Optic Fibre Cable and associated terminal equipment to the North of the GRID beyond Shiroro T.S.viii. Extension of Optic Fibre Cable to the Eastern part of the GRID beyond Benin T.S., Sapele and Delta Power Stations. If these extension projects are implemented, it will provide redundancy for communication system and further ease the problem of communication for System Operations and Control.ix. At present skywires bearing Optic Fibre Cable on 330KV Transmission line circuit S5B/G3B is still out. Hence failure of Optic Fibre voice communication to such stations as Delta P.S. and Sapele P.S. It is expedient that action be completed on the replacement of both the skywire and the fibre cable so as to restore voice communication to these stations especially Delta P.S. that is being used for black starting the power system whenever it suffers total collapse. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 59
  • xi. FAULTY SOPHO-ETL CONNECTIONSAiyede – Osogbo – Ikeja West PLC LinksRestoration of the following PLC ETL500 is still outstanding: a. Osogbo – Aiyede ETL540 Link b. Osogbo – Ikeja West ETL81 Link c. Osogbo – Akangba ETL81 LinkEfforts are on to restore them to add more channels for Osogbo – Lagos communications.xii. COMMUNICATION IN NEW POWER STATIONSThe following Power Stations are newly built and integrated into the GRID but withoutcommunication facilities: a. Okpai P.S. b. Omotosho P.S. c. Geregu P.S. d. Olorunsogo P.S. e. Omoku P.S.For ease of co-ordination by the National Control Centre, there is need for theManagement to expedite installation of adequate telecommunication facilities in all thesestations.xiii. RESTORATION OF PAX TO EGBIN P.S.Above system which was faulty in year 2006 was restored and hence NCC, Osogbo couldcommunicate well with the Power Station on PAX for effective operations and control ofthe GRID.xiv. RESTORATION OF OPTIC FIBRE COMMUNICATION IN LAGOS REGIONThe supposed alternative communication media to the Powerline Carrier (PLC) is theOptic Fibre communication system. Hitherto, this system between Lagos and otherstations like NCC is still out of service. The vandalized skywires replacement is not yetcompleted. When this is done voice communication between the NCC and Lagos zonewill be greatly enhanced.xv. BACK-UP COMMUNICATIONS – NITEL AND GSMNITEL and GSM communication facilities are two of the two back-up systems ofcommunication employed at the National Control Centre for operations of the GRID. At Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 60
  • present NITEL Direct Exchange lines is no longer reliable nor dependable. This is due tothe problem the communication company is currently experiencing in the country.xvi. COMMUNICATIONS AT THE 132KV SUBSTATIONS IN OSOGBO REGIONBoth the VHF, HF Radios and the Powerline Carrier Communications at the 7no. 132KVsubstations in Osogbo Region were sustained by constant preventive and break downmaintenance throughout the period under review.xvii. HIPATH PABX FOR OPTIC FIBRE CONNECTIONSThere was a major breakdown of the HIPATH Telephone exchange connected to theOptic Fibre Cable at SNCC, Shiroro due to lightning strike in the station. As a result ofthis the voice communication using the Optic Fibre medium was greatly hindered. Thisresulted in impairment of GRID Operations and Control. The communication crew atShiroro led by the Principal Manager (Comms.) of the Region worked hard at restoringthe affected electronics modules on the exchange. The job was successful and voicecommunication is now back serving as alternative to PAX voice communication.xviii. OPTIC FIBRE VOICE COMMUNICATION TO BENING T.S.Voice Communication to Benin T.S. is not working. This is because of a problem on theOLTE 8 Optic Fibre terminal equipment carrying an alarm F22. Effort is being made toclear this problem so as to reestablish alternative communication by Fibre to PAX/PLCCommunication in the station.xviiii CONCLUSIONThere are two major constraints to the performance of the System Communicationmaintenance division viz: - Inadequate funding - Lack of functional vehicles for maintenance tours.If these are appropriately provided, more achievements will be made in the years ahead.This will lead to: - Improved system operations and control. - Wheeling of more energy. - Increased revenue accruing to the Power Holding Company.2.1.1 SUPPLEMENTARY NATIONAL CONTROL CENTRE (SNCC)2.1.1.1 THE EXISTING SCADA/EMS NETWORK Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 61
  • The existing SCADA/EMS network at the SNCC is still functioning though with anumber of RTUs in disturbed status. Its mirror image at the NCC is intact and is stillbeing utilized by the NCC in monitoring load flows or transformer loadings at 330KVsubstations.2.1.1.2 VPN CONNECTION AND DNS CONFIGURATIONAs a result of the NCC Upgrade, a virtual private network (VPN), an Internet connectionwas established by Siemens at the SNCC. This was essentially to link the twoSCADA/EMS data base masters of the project which are:(1) Siemens PTD LAN, located at Germany-Nuremberg, this is mainly for System software Developers where all the Spectrum source codes are resident.(2) SCADA/EMS LAN, located in Nigeria at the SNCC, for customer support.It was desired that the two Master Data Base be linked together via the VPN connectionsince the SNCC is to:(1) Serve as a Clear-Case (Development(2) Distribute source code updates to other Centres, NCC, RCC1 and RCC2.(3) Provide Solaris Security Patches.In the process of establishing the link, the Shiroro Internet connection was found to bevulnerable to both virus infection and hackers as such insecure. This portends danger notonly to the SCADA/EMS Master Data Base at Shiroro but also to the Project at large.Subsequently, the attention of the IT Department of TCN HQ was drawn to the insecurityissue. At the interim, they immediately mobilized and installed an enterprise Anti-Virus,MCAfee, on the LAN Server to serve as a Fire Wall. Much later, the SNCC LAN wasconfigured by the IT staff into a Domain Architecture (DNS), more secure environment.2.1.1.3. RTU ADAPTION WORK AND EXTENTION OF SCADA/EMS TO 33KV FEEDERSThe RTU adaptation works of the NCC Upgrade at the numerous 330KV and 132KVsubstations are still going on throughout the Country. The exercise is being conductedjointly by Siemens and PHCN staff.The SCADA/EMS Upgrade is now extended to incorporate 33KV feeders in itsmonitoring coverage. Subsequently, the implementation of the Software configurationsof the feeders has started in earnest at the SNCC, jointly by Siemens and PHCN staff.2.1.1.4. OPTIC FIBRE COMMUNICATION LINK FROM SHIRORO TO ABUJA Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 62
  • As part of the Upgrade, Shiroro ACC is to link to Abuja ACC directly via an existingOptic fibre which is inbuilt in the sky wire of the Shiroro – Abuja 330KV line.The installation works of the terminal equipments have commenced at the SNCC. So far,a PDH (Optic Fibre Equipment) and a PABX (Intercom exchange) with its associatedMDF have been installed. The installation exercise is expected to be accomplished bythe first quarter of next year, 2008.2.1.2. NCC Upgrade ProjectInstallation of the state-of-the-art Supervisory Control and Data Acquisition (SCADA)Energy Management System (EMS) that commenced in 2005 progressed further in 2007.In the year SCADA/EMS equipment were installed in three Regional Control Centres(RCC) namely Shiroro, Benin and Ikeja West. The installation of NCC Osogboequipment is still being delayed by the non-completion of the new NCC building.Data entry for building of the SCADA data base is completed for 330kV, 132kV. Workhas also commenced on the exercise for 33kvRemote Terminal Units (RTU) and Telecommunication commissioning are ongoing inLagos area for Ikeja West RCC.RTU adaptation work is still going around the country for 132kV and 33kV stationswhile 330kv stations and Power stations are expected to commence when NCCSCADA/EMS installation is completed.2.2 Generation ConstraintsTotal MW site ratings installed capacities at all PHCN power stations and theIndependent Power Producers (IPP) that contributed to the grid generation in 2007 was7777.40MW. The IPP included AES, Okpai, Ajaokuta and Omoku (River State) powerstation that contributed about 910MW of installed capacity to the grid.Geregu and Omotosho power stations were tied to the grid on February 20, and June 7,2007 respectively.The average available capacity was 4156.9MW. This was greater than 2006 averageavailability of 3889.36MW by 266.83MW.The availability factor (average availabilitydivided by the installed capacity) was 53.44%.The percentage was rather low due to limitation in supply of natural gas to Egbin powerplant throughout the year. Also some generating units capacity are limited due to faults.2.3.0 Transmission Constraints Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 63
  • Transmission constraints as at the end of December 2007 were subdivided into variouscategories viz.:(1) Transmission Lines - 330KV and 132KV(2) Shunt reactors(3) Transformers.2.3.1 Transmission Lines2.3.1.1 Ikorodu-Ayede-Osogbo 132KV CircuitThis circuit which was constructed around 1964 is aging.Result:Frequent conductor/jumpers cut along the entire stretch.Implication:Frequent and prolonged line outages on this circuit.2.3.1.2 Akangba-Ojo 132KV CircuitThe huge refuse dumps, heavy industrial built-up and proliferation of residentialhouses/stations under these lines have been reported since 1983.Results:(a) Frequent earth fault due to reduction in the overhead clearance and Refuse burning.(b) Industrial pollution of lines and insulators.Implication:Frequent forced line outages on these circuits.2.3.1.3 Gombe-Maiduguri 132KV CircuitThis 132KV composite circuit (Gombe-Dadinkowa 150mm2, Dadinkowa-Maiduguri100m2 single line) is 310km long.Result: Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 64
  • 20KV - 40KV voltage drop occurs between Gombe and Maiduguri, Gombe 132KV busvoltage has to be run as high as between 140KV - 145KV to enable acceptable voltagelevels at Maiduguri.Restriction:Gombe 132KV bus had to be run split to enable one transformer feed the Maiduguri andYola lines experiencing high voltage drop. The other transformer fed Bauchi andPotiskum lines.2.3.1.4 New-Haven-Oturkpo-YandevThis 132KV circuit (New Haven/Oturkpo 150mm2 single line configuration) is about330km long.Results:About 20KV Voltage drop occurs between New Haven and Yandev resulting in very lowvoltages and poor quality of power supply to these areas. The situation has been partiallyimproved by the commissioned 33KV, 2.8MVAR capacitor banks at Yandev. Areas stillexperiencing low voltages include Gboko and Makurdi fed from Yandev at 33KV.Restrictions:New Haven 132KV bus voltage had to be run high because the bus cannot be run splitsince the second 150MVA, 330/132/33KV transformer was unavailable due to tapchanger problem.2.3.1.5 Benin-Onitsha-Alaoji 330KV lineBenin-Onitsha-Alaoji 330KV axis is limited by single line contingency.Results:If Benin/Onitsha line or Onitsha/Alaoji line tripped:(a) Afam and Okpai P.S. generating units shut down on overload or reverse power protection depending on generation output.(b) Alaoji complex is usually plunged into blackout resulting in partial system collapse.Restrictions: Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 65
  • Afam and Okpai P.S. units were greatly stressed due to frequent shutdowns arising fromtransmission line faults.Restoration of electricity supply was prolonged because of voltage control problems.About 11 State Capitals and environs usually experienced prolonged blackout when B1Ttripped six States, when Onitsha/Alaoji T4A tripped and Afam and Okpai P.S.generation was forced out.Recommendations:(1) There is urgent need to construct the second Benin/Onitsha 330KV circuits which had been under plan for some years past.(2) Construction of the proposed Alaoji/New Haven/Markurdi/Jos 330KV Circuits configuration should be expedited.(3) Improve generation output from Afam P.S. so that it could sustain the load demand within that complex.Grid security and voltage to the eastern system will be enhanced.2.3.1.6 Aba-Itu 132KV LineThis single circuit which links Aba with Itu, Calabar and Eket 132KV stations, has onlyone breaker at Aba with no by-pass facilities.Implication:Breakdown of Itu 132KV breaker at Aba means prolonged blackout of Itu, Eket andCalabar 132KV complex serving the majority of Cross River/Akwa-Ibom states.Recommendation:By-pass facilities should be provided for the Itu breaker at Aba to avoid frequent blackoutin the two states whenever the breaker is out.The fault throwers at Calabar and Eket should be replaced with standard circuit breakers.Similarly all fault throwers still left in the system should be replaced with circuitbreakers.2.3.1.7 Delta - Benin 132KV DC Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 66
  • Delta – Benin 132KV had circuit breaker problems at both ends.Results:When circuits G3B and G1W were not available; there will be no outlet for Delta G.S.generation through the interbus transformer to Benin T.S. on 132KV circuit.Restriction:Delta G.S. generation is available only 330KV circuit.Recommendation:For grid security, efforts should be made to restore the circuit back to service.2.3.1.8 Delta/Sapele/Aladja 330KV ConfigurationFollowing the commissioning of Benin/Delta 330KV circuit G3B in 1996, the existingconfiguration consists of Delta/Aladja 330KV circuit G1W supplying Aladja from DeltaPower Station and Sapele/Aladja 330KV circuit S4W feeding Aladja Steel from SapelePower Station.Results:This arrangement where power flows from Sapele/Delta P.S. through Aladja Delta SteelCompany - a PHCN customer, is a defective arrangement as it complicates faulttracing/clearing and precise energy metering since Aladja Steel switchgear is notmaintained and operated by PHCN.Recommendations:The existing Sapele/Aladja 330KV line S4W need to be disconnected from Aladja Steeland terminated on Delta IV 330KV bus.The second Delta/Aladja 330KV circuits should also be considered. These arrangements would providetwo 330KV power route for Delta generation one through Delta/Benin 330KV circuit G3B andthe other through the proposed Delta/Sapele 330KV circuits. It would also ensure tworadialpower routes to Delta Steel Company, Aladja.PHCN should negotiate to acquire the sub-station at Delta Steel Company, Aladja.Management’s present effort to man/redeploy System operators to Delta Steel Company,Control room is a very good development. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 67
  • 2.3.2 Shunt Reactors(i) Onitsha 9R2 - 30MX reactor was out due to low resistance.Result:High voltages were experienced at Onitsha and New Haven substations respectively.Implication:When Afam P.S. generation is separated, it took quite a long period to synchronise thestation to the grid because of high voltage differences. Many areas have to be in darknessto prevent Afam generation from collapsing.(ii) Osogbo 4R1 – 75MX reactor was out of service due to faulty winding.Result:Excessive high voltages which sometimes were above the statutory limit of 346KV wereexperienced at Osogbo since the Osogbo 75MX reactor was out of service.(iii) Birnin Kebbi 19R1 – 30MX Reactor was unavailable due to burnt under- ground cable.Result:High voltages which occasionally exceeded statutory limit of 346KV.2.3.3 CRITICAL TRANSFORMER LOADING POSITIONS AS AT DECEMBER, 2007 (A) Transformers that were loaded 100% and above of transformer rating:-This category of transformers very urgent attention. The situation where some of themhave to be loaded for hours above 100% rating reflects the urgent.Need for the affected transformer banks to be reinforced.STATION TX TX MVA RATING % TIME & NOM. RATING KV LOADING DATELAGOS REGIONMaryland T1 30 132/33 113 2HRSMaryland T3 30 132/33 113 2HRSIkorodu T1 60 132/33 110 2HRSEgbin IBTR1 150 330/132 104 2HRSEgbin IBTR2 150 330/132 104 2HRS. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 68
  • AJA T3 150 330/132/33 103 2HRSIkorodu T2 60 132/33 102 2HRSMaryland T2 40 132 102 2HRS.Abeokuta T2 30 132/33 100 2HRS.Ejigbo T1 30 132/33 100 2HRS.Ejigbo T2 30 132/33 100 2HRSSHIRORO REGIONSokoto T2 30 132/33 105 2HRS.Suleija T1 7.5 132/11 103 2HRS.Birni-Kebbi T7 30 132/33 102 2HRS.KADUNA REGIONKankia T1 7.5 132/33 101 2HRS.ENUGU REGIONAbakiliki T3 15 132 109 2HRSOnitsha M.T/F 30 132/33 103 2HRS.Nsukka T1B 7.5 66/33 103 2HRS.(B) Transformers that were loaded between 85% and 99% of transformer ratings:-LAGOS REGIONOgba T3 30 132/33 99Isolo T1 30 132/33 98Papalanto T1 15 33 95Papalanto T2 15 132/33 95Aja T2 60 132/33 89Itire T1 30 132/33 88Isolo T1 15 132/11 88Ikeja West T1A 150 330/132/33 87Ikeja West T1B 150 330/132/33 87Ikeja West T2A 150 330/132/33 87Ikeja West T2B 150 330/132/33 87Isolo T3 15 132/11 86Alimosho T3 30 132/33 86SHIRORO REGIONSuleija T3 30 132/33 99Akwanga T1 30 132/33 93Birni-Kebbi T6 15 132/33 86 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 69
  • KADUNA REGIONMando T.S T3 18.75 132/33 97Zaria T2 15 132/11 90Kaduna Town T2B 15 132/11 89OSOGBO REGIONOsogbo 4T5 30 132/33 97Ife T2 30 132/33 95Osogbo 4T3 30 132/33 95Ondo T2A 30 132/33 88BENIN REGIONBenin T23 30 132/33 94Irrua T1 60 132/33 92Okene T2 40 132/33 89Benin T22 60 132.33 88Benin T21 60 132/33 87Amukpe T1 30 132/33 86ENUGU REGIONAwka TR3 30 132/33 97New Haven TR3 60 132/33 94Awka TR1 30 132/33 94Onitsha M.T/F 15 132/11 91Abakaliki T1 30 132/33 88Onitsha TR11 60 132/33 88PORTHARCOURT REGIONAlaoji T1A 150 330/132/33 93Alaoji T2A 150 330/132/33 93Owerri MOB 40 132/33 93P/H Main T3A 60 132/33 91Aba M.T/F 30 132/33 86(C) Transformers that were loaded between 60% and 84% of transformer ratings:-LAGOS REGIONOjo T1 30 132/33 84Ojo T2 30 132/33 84Alimosho T1 30 132/33 82Ilupeju T4 30 132/33 82Isolo T3 30 132/33 80 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 70
  • Aja T4 150 132/33 78Ilupeju T3 15 132/33 76Oworonsoki T1 30 132/33 76Amuwo-Odofin T1 40 132/33 75Oworonsoki T2 30 132/33 75Apapa-Road T1 30 330/132/33 75Otta T2 60 132/33 75Alausa T2 60 132/33 74Otta T1 40 132/33 74Abeokuta T1 30 132/33 74Agbara T1 45 132/33 72Agbara T2 45 132/33 72Apapa-Road T2 30 132/33 70Amuwo-Odofin T3 40 132/33 70Ogba T2 60 132/33 69Akangba 10T1A 60 132/33 68Itire T3 40 132/33 67Akangba 5T1A 90 330/132/13.8 66Akangba 5T1B 90 330/132/13.8 66Akangba 5T2B 90 330/132/13.8 66Apapa-Road T4(MOB) 15 132/11 66Akangba 10T2B 60 132/11 65Amuwo-Odofin T2 30 132/33 65Abeokuta T3 30 132/33 65Ilupeju T1 15 132/11 64Aja T1 40 132/33 63Alagbon T1 60 132/33 61Alagbon T2 60 132/33 61Akangba 5T4A 150 330/132/33 61Ijora T1A 30 132/33 61Ijora T1B 30 132/33 61SHIRORO REGIONKontagora T1 30 132/33 82Minna T2 30 132/33 79Sokoto T1 30 132/33 78Minna T1 30 132/33 78Kubwa (MOB) 40 132/33 71Apo T.S T1 45 132/33 67Apo T.S T2 45 132/33 67Katampe T1 60 132/33 67Katampe T1 60 132/33 67Apo T.S T3 45 132/33 66KADUNA REGION Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 71
  • Funtua T3 30 132/33 84Dan-Agundi T1 60 132/33 83Hadejia T1 15 132/33 81Dan-Agundi T3 60 132/33 80Kumbotso T2 40 132/33 79Mando T.S T1 30 132/33 79Kaduna Town T3 60 132/33 78Zaria T4 40 132/33 77Mando T.S T2 60 132/33 71Dakata T3 30 132/33 70Katsina T3 30 132/33 68Funtua T1 5 132/11 67Kumbotso T2A 150 330/132/33 67Dakata T1 30 132/33 66Gusau T1B 30 132/33 64Kumbotso T1A 150 30/132/33 64Kumbotso T3 30 132/33 62Dakata T2 60 132/33 61Kaduna Town T1A 30 132/33 61Kankia T2 30 132/33 61BAUCHI REGIONGombe T4 30 132/33 82Potiskum T2 30 132/33 75Jos T1A 150 330/132/33 72Jos T4 60 132/33 72Bauchi T3 40 132/33 67Savannah T1 15 132/33 64Jos T3 60 132/33 60OSOGBO REGIONAkure T2A 30 132/33 84%Sagamu T1 30 132/33 75%Iseyin T.S T1 30 132/33 74%Ilorin T2A 30 132/33 72%Ijebuode T1 30 132/33 70%Omuaran T1 30 132/33 69%Ayede T3 60 132/33 67%Ayede T1B 150 330/132/33 65%Ayede T2A 150 330/132/33 65%Ibadan North T1 30 132/33 61%BENIN REGION Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 72
  • Effurun T23 60 132/33 79Ughelli/Delta T2 30 132/33 76Okene T1 30 132/33 67ENUGU REGIONNsukka T1A 7.5 66/33 84Yandev T2 15 132/33 83Onitsha TR13 60 132/33 82Oturkpo T1 7.5 132/33 81New-Haven TR1 30 132/33 77New-Haven TR2 30 132/33 77Onitsha TR12 15 132/11 71Nkalagu T2A 15 132/33 62PORTHARCOURT REGIONP.H Main T2A 45 132/11 82P.H Town T2A 30 132/33 79Calabar T1 30 132/33 78Aba T1B 30 132/33 76Itu T1A 15 132/33 76P.H Town T1B 30 132/33 76Owerri TR1 45 132/33 71Uyo T2B 40 132/33 70Aba T2B 45 132/33/11 64 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 73
  • 3.0 REINFORCEMENT AND REHABILITATION OF NATIONAL GRIDL isted in appendix are the executed rehabilitation work in both the Power Stations and Transmission network in 2007.Below are a few of prominent rehabilitation implemented in 2007.22/01/07 P.H. Main T/S 60MVA 132/33kV transformer T3A was energized from Omoku P/S with an initial load of 38MW. This enhanced the grid reliability.07/02/07 Ikeja West (Nigeria)/Sakete (Benin 330 kV Line was energized from Ikeja West.12/02/07 Replacement of the vandalized Optic Fibre Cable along Jebba/Shiroro 330kV Line CCT J3R.09/03/07 Egbin/Aja 330kV CB 52-16 North bus breaker CTs 25 & 26 were replaced with new sets of CTs. Equipment protection was reinforced.20/03/07 Geregu GT13 was synchronized to the grid and loaded up to 15MW.20/03/07 Vandalized Optic Fibre Optic Cable along the sky wire of 330 kV Osogbo/Ayede Line (CCT. H2A) CB were re-strung at both ends. Improved communication and SCADA data acquisition resulted.21/03/07 Three new sets of CTs were installed on Jebba/Osogbo 330kV Line 3 (CCT. J3H) at Osogbo T.S. end.26/04/07 Kano/Dutse/Azare 132kV Line was formerly commissioned by the President of the Federal Republic of Nigeria.07/06/07 Omotosho P.S. 330kV T.S. was energized from the grid.14/06/07 Omotosho P/S GT1 was synchronized to the grid with initial load of 5MW.17/06/07 Birnin-Kebbi/Niamey 132kV Line was restored after amending cut sky wire on tower No. 430 and 434.23/07/07 Omotosho P/S GT2 was tied. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 74
  • 07/09/07 Afam P/S GT17 was tied on test run with 30MW only10/11/07 Jebba 2G1 was tied after the purification of the unit Governor System Oil. System generation stability was thus ensured.19/11/07 Benin/Onitsha 33kV Line (CCT. B1T) was restored after the replacement of the burnt red phase CVT at Onitsha T/S. The system security was reinforced. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 75
  • 4.0 SYSTEM DISTURBANCESA Unified 330kV network was operated in 2007 unlike year 2002, 2003 and 2004 when the grid was split into islands A1 and A2.There were eighteen (18) major System Disturbances in the year. This reduced by two(2) 10% on comparison with 2006 value of 20 and was 14.20% relatively lower than year2005 figure of 21.Table 14A compared various values of grid disturbances in the past 20 years – 1987 to2007.A summary of the causes of all system disturbances in 2007 (Total and PartialDisturbances) is depicted in table 14B.4.1. TRANSMISSION SYSTEM FAULTS88.89% of all the System Disturbances in 2007 were caused by transmission faults.Sixteen (16) of the major System Disturbances were due to transmission faults.Analyses of the various events precipitating the System Disturbances generally reflectednegligence in clearing of all types of encumbrances that could foul the transmissioncircuits. Most of the like trippings that eventually resulted in system disturbances weretransient. At times system restoration was through the same line that led to thedisturbance.Occasionally the disturbances were traceable to protection problems, especially lack ofproper coordination of distance relays, failure and spurious relay operations.Other transmission faults that led to system disturbances in 2007 were incidents of circuitbreaker and isolator explosion at Benin substation and shattering of current transformer atEgbin substations.4.2 GENERATION SYSTEM FAULTSOnly 2 of the 18 major disturbances were triggered by generation loss. System collapsewould have been averted had the governor systems on both hydro and thermal generatingunits responded fast enough to generation loss. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 76
  • 5.0 ACCIDENTS AND MISHAPSI n 2007, a total of twenty six (26) accidents and mishaps were reported to National Control Centre. In comparison with 2006, it rose by 44.44%.Major mishaps included Current Transformers explosion at: • Osogbo 330/132kV Sub-Station on Jebba/Osogbo 330kV Lines (CCt J3H). • Egbin 330/132kV Sub-Station on the Red phase of Egbin/Aja 330kV Line 2 (N4J) • Delta T.S 45MVA 132/33kV Transformer and 30MVA 132/33kV Transformer T2 three phase pole • Delta T.S 45MVA 132/33kV Transformer and 30MVA 132/33kV Transformer T2 three phase pole. • Mando T.S. 60MVA, 132/33kV Transformer T2 red phase current Transformer.Several conductors and towers vandalization were recorded all over the grid. Mostworrisome was the incessant vandalization of Optic Fibre Cable that provided SCADAdata through Remote Terminal Unit (RTU) to N.C.C.None of these accidents and mishaps claimed lives.A detailed description of the various accidents and mishaps is contained in appendix 3 ofthis report. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 77
  • 6.0. CONCLUSIONS AND RECOMMENDATIONSG eneration availability was boosted in 2007 with the commissioning of Geregu Power Station (414MW), Omotosho (262.2MW) and Olorunsogo (38MW).However, incessant low gas pressure, gas shortage and condensates accumulation in thegas pipe lines stymied full utilization of the available generation capacity. The existingPower Station such as Egbin/AES, Delta and Afam were equally affected by the acutegas restriction. Egbin with capacity of 1320MW was limited continuously to about500MW in 2007.In spite of the above, the load demand of about 10,500MW was far above the totalavailable generation of an average of 4124.6MW. The shortage prompted an all yearround load shedding in order to maintain power balance. This implied that the grid wasoperated at alert state throughout the year.It took operational proficiency and pertinacity of the staff and Management of theNational Control Centre Electric Power Business Units and Transmission Company ofNigeria (TCN) to sustain the system,In 2007, 23,186,542.92MWH energy was pooled into the grid. Energy sent out of all thepower stations into the Transmission Company Nigeria PLC (TCN) grid was22,255,754.83MWH.Transmission losses and substation consumption in 2007 was 8.25% of the total energysent out as the power station consumption was 4.01% of the total energy production inthe year.The year 2007’s maximum annual coincidental peak generation of 3599.6MW occurredon 11th January, 2007 at 2200hrs.The network was firmly integrated into a single grid throughout 2007.Black starting the grid in events of total system failure was mainly from Delta PowerStation. While Delta prepared for black starting, Shiroro Power Station was always onhand to supply Abuja complex promptly.Once in the year system restoration commenced from Shiroro Power Station as one faultor another hindered system restoration from Delta Power Station.Grid black starting from Kainji Power Station remained unfulfilled dream. It isanticipated that the World Bank sponsored retrofitting project would offer a freshopportunity to restore Kainji Kaplan units to their traditional role of black starting thegrid in the event of a major system disturbance. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 78
  • None of the twenty six (26) accidents and mishaps recorded in 2007 claimed lives.Management’s attention is hereby drawn to the following:1.0 Some of the ongoing National Integrated Power Projects (NIPP) are being Commissioned. Gas availability to fire the turbine has been a major constraints. Urgent lasting solution to gas problems need be sought. Expedition of action on Completion of NIPP transmission and Distribution part of the project is highly recommended in order to eliminate congestion and lines over load.2.0 Rehabilitation of Turbine governors and droop setting coordination in the System requires urgent attention. A Task force should be constituted for this assignment.3.0 The effort of the Management is hereby appreciated as regards the installation of the Very Small Aperture Terminal (VSAT) Satellite facility at the National Control Centre, Abuja, Kainji G.S. and SNCC, Shiroro. It has really enhanced dissemination of daily operational information through the internet by E-Mail. However the Voice on Internet Protocol ((VOIP) has not recorded any success as the voice facility has been out for long.4.0 Internet connectivity can further be extended to stations already connected by Fibre Optics System if Computer Terminals are provided at such stations with the Main Server located at the National Control Centre, Osogbo already on the VSAT. This will completely replace the use of TELEX with which daily Operational information dissemination was implemented. Though optic fibre Communication technology is being introduced into PHCN system all other communications modes should not be discarded in fact a combination of available communication media should be harnessed to make sure that there are at least three different communication media to important Power and transmission stations. Efficient system operations would be a mirage without efficient communication facilities. 5.0 Optic Fibre Cable vandalization continued unabated in 2007. This was ominous to the efficient, effective and reliable communication for system operations. Management is hence urged to employ every possible means to check the menace of frequent vandalization of Optic fibre cables.6.0 Future Hydro development should emphasize on variable blades (Kaplan) units that are more flexible in operation i.e., broaden grid system spinning reserve base aid system frequency control and enhances optimal water resource Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 79
  • There are already too many base load units in the grid, which Inhibit effective system frequency control. Black starting the system after a major system shutdown reveals that these units are not helpful because they cannot be part loaded as required during restoration.7.0 Management is urged to consider the development of Hydro Horizontal Turbine Generators of lower capacities. Several smaller Dams and Generating stations could be developed down stream of Jebba before Lokoja on River Niger and down stream of Zungeru on River Kaduna. Many of such lower capacity generators while boosting system generation will also increase the system inertia, efficient water resource management and hence improve the stiffness of the system. This suggestion should be given serious considerations especially in the wake of recent developments in the upper Niger. Mali and Niger have already secured loans to develop Tosaye Dam in Mali and Kandaji Dam in Niger Republic. These Dams are not only for power generation but mostly for irrigation. The Negative impact of these Dams on Kainji and Jebba Power Stations and Reservoirs will be enormous. It’s only wise that we quickly harness our internal Hydro resources before they start the building of those dams at Mali and Niger. This will ameliorate the negative impact the dams on the upper Niger will have on Kainji and Jebba Power Stations.8.0 Feasibility studies on Zungeru project might have been completed but if design and construction has not begun, it may still be feasible to make all the units (Variable Blades) Kaplan by playing down on the Operating Head. This certainly will go along way in improving system stability, Frequency control and efficient water resource management. The scope of the project should not be Scaled down. With six installed generators, the firm capacity is five, giving room for Operational exigencies, maintenance and effective water management. 9.0 Expediting action in replacing all the remaining 132kV Fault Thrower Switches in some parts of the grid with SF6 Circuit Breakers. This will avoid the unnecessary interruption of supply to customers due to the long delays associated with the resetting of switches each time they operate. The stresses (short circuit MVA) imposed on the grid system each time the Fault Thrower switch operates will also be avoided.10.0 Regular staff training in every field of PHCN operations should be intensified after a proper training needs assessment. In addition to training, the right working tools should also be provided for the staff. The Management is enjoined Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 80
  • to train staff in specialized fields such as turbine governor and under water maintenance for Kainji, Jebba and Shiroro dams. Time and money could be saved, as compared to the present practice of waiting for weeks for Divers from Lagos to effect maintenance at the Dams.11.0 The efforts of the SAP and PHCN Management in addressing the issue of Quality and quantity of gas supply to our Thermal Power Stations by Nigerian Gas Company is appreciated. The damages and loss incurred by PHCN as a result of bad quality of gas supplied to our power stations is enormous. Further losses incurred by PHCN arising from bad quality gas supply to our facilities by Nigerian Gas Company should attract serious sanction on Nigerian Gas company.12.0 Transmission Company of Nigeria (TCN) is the biggest among the other networks being proposed for West Africa Power Pool comprising, CEB of Republic of Benin and Togo, VRA of Ghana, CIE of Coted’voire, Sonabel of Bourkina Faso and Nigerlec of Niger hooked up to TCN of Nigeria, for the success of the interconnection.(i) Management is urged to ensure that the West Africa Power Pool Operating Manual produced recently by stake holders’ countries are strictly complied with.(ii) Urgent funding of WAPP’s System Operation Training Centre established at National Control Centre, Osogbo is recommended.Engr. M. O. IyohaGeneral Manager (S/O)National Control Centre, Osogbo. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 81
  • SECTION 7.0 APPENDICES1.0 POWER STATIONS AVAILABILITY AND COINCIDENT PEAK GENERATION RECORD IN 20072.0 2007 GRID REINFORCEMENTS AND REHABILITATION RECORDS.3.0 SYSTEM DISTURBANCE, ACCIDENTS AND MISHAPS RECORDS IN 2007. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 82
  • APPENDIX 1.02007 POWER STATIONS AVAILABILITY AND COINCIDENTPEAK MW GENERATION RECORDSTABLE 15: MONTHLY MAXIMUM DEMAND/GENERATION ANALYSIS IN (MW)TABLE 16: SYSTEM GENERATION PEAK LOAD (FORECAST & ACTUAL)CHART MONTHLY PEAK DEMAND FORECAST & ACTUAL WEEKLY30 - 31 PEAK TOTAL MW GENERATION HISTOGRAM.CHART 2007 POWER STATIONS DAILY USABLE (MW),32- 46 GENERATING/CAPACITY SPECTOGRAPHSCHART DAILY GRID GENERATION AVAILABILITY STATUS FOR THE 47 YEAR 2007. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 83
  • TABLE 15. MONTHLY MAXIMUM DEMAND /GENERATION ANALYSIS IN MW JANUARY - DECEMBER 2007 DATE OF TIME OFMONTHS KAINJI JEBBA SHIRORO AES EGBIN SAPELE AFAM DELTA OKPAI AJAOKUTA IJORA CALABAR OMUKU GEREGU OMOTOSHO PEAK PEAK PEAK JAN. 401 498 539 289.1 652 65 180 453 438 45 0 0 39.0 0 0.0 3599.6 1/11/200 08:00 PM Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo FEB. 251 400 412 221.8 578 65 110 444 427 80 0 0 38.0 0 0.0 3023.8 05-Feb-07 09:00 PM MAR. 413 340 256 157.6 565 60 70 352 212 84 0 0 60.3 139 0.0 2717.9 3/23/200 11:00 PM APR. 492 330 381 220.3 617 61 130 359 351 90 0 0 76.0 228 0.0 3335.3 30-Apr-07 8:45 PM MAY. 462 346 379 219.7 566 0 260 248 373 85 0 0 39.7 219 0.0 3320 16-May-07 08:00 PM JUN. 179 237 375 223.2 626 65 260 270 235 35 0 0 65.5 290 0.0 2858.7 12-Jun-07 8:00 PM 84 JUL. 93 175 396 269.5 561 64 250 412 477 54 0 0 70.7 296 75.9 3193.9 27-Jul-07 09:45pm AUG. 344 480 560 207.6 288 110 125 346 472 35 0 0 70.0 181 37.7 3256.3 31-Aug-07 09:30 PM SEP. 384 527 547 223.7 585 107 200 326 424 0 0 0 74.0 180 38.0 3595.7 05-Sep-07 07:00 PM OCT. 420 538 417 253.8 563 44 250 358 477 0 0 0 47.5 145 39.1 3552.4 11-Oct-07 9:15 PM NOV. 440 428 425 299.7 376 103 250 331 473 0 0 0 44.0 146 37.5 3353.2 12-Nov-07 9:15 PM DEC. 452 372 278 249.1 568 84 250 254 467 22 0 0 40.0 285 71.8 3392.9 15-Dec-07 9:30 PM
  • TABLE 16 SYSTEM GENERATION PEAK LOAD (FORECAST AND ACTUAL) JANUARY - DECEMBER 2007 WEEK 1 WEEK 2 WEEK 3 WEEK 4 WEEK 5 MONTHLY PEAK LOADMONTH ORECAS ACTUALFORECASTACTUALFORECAST CTUALORECAST CTUALORECASTCTUAL A F A F A FORECAST ACTUALJAN. 9100 3500.8 9100 3599.6 9100 3338 9100 3140 9100 2910 7280 3599.6 Generation and Transmission Grid Operations-2007-National Control Centre, OsogboFEB. 9250 3023.8 9250 2918.1 9250 2949 9250 2719 0 0 7400 3023.8MAR. 9700 2579.3 9700 2692.8 9700 2639 9700 2718 9700 2648 9700 2717.9APR. 10000 2640.8 10000 3077.3 10000 3166 10000 3262 10000 3335 10000 3335.3MAY. 9400 3267.1 9400 3302.2 9400 3320 9400 2944 9400 2916 9400 3320.1 85JUN. 9300 2807.2 9300 2858.7 9300 2851 9300 2773 9300 2568 9300 2858.7JUL. 9000 2708.7 9000 2840 9000 3014 9000 3194 9000 3039 9000 3193.9AUG. 8800 3006.3 8800 3188.8 8800 3201 8800 3224 8800 3256 8800 3256.3SEP. 10000 3595.7 10000 3392.4 10000 3414 10000 3471 10000 3385 10000 3595.7OCT. 10100 3356.1 10100 3552.4 10100 3003 10100 3017 10100 2607 10100 3552.4NOV. 10200 3062.2 10200 3353.2 10200 3167 10200 3288 10200 3146 10200 3353.2DEC. 10300 2754.2 10300 3337.2 10300 3393 10300 3352 10300 3201 10300 3392.9
  • TABLE 17. SUMMARY OF OCCURRENCE MAXIMUM PEAK LOAD DEMAND IN YEAR 1992 - 2007 YEAR PEAK LOAD (MW) MONTH TIME OF OCCURRENCE REMARK 1992 2382.00 10-Dec-92 8:30PM 1993 2330.00 10-Nov-93 07:00PM 1994 2446.00 07-Feb-94 08:00PM 1995 2452.00 13-Nov-95 07:30PM 1996 2470.00 06-Dec-96 07:30PM 1997 2457.00 29-Jan-97 07:45PM 1998 2412.00 07-Sep-98 09:30PM 1999 2458.00 19-Nov-99 07:30PM 2000 2499.00 31-Dec-00 08:15PM 2001 2934.49 31-Dec-01 08:30PM 2002 3223.40 05-Dec-02 08:45PM 2003 3479.30 29-Aug-03 07:45PM 2004 3427.5 30-Sep-04 08:00PM 2005 3774.4 08-Aug-05 20:15PM 2006 3682.3 27-Oct-06 06:00AM 2007 3599.6 11-Jan-07 22:00PM Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 86
  • MONTHLY PEAK FORECAST AND ACTUAL GENERATION JANUARY-DECEMBER 2007, CHART 30 (SEE TABLE 16) 12000 10000 SYSTEM GENERATION IN MW 8000 6000 4000 2000 0 JAN. FEB. MAR. APR. MAY. JUN. JUL. AUG. SEP. OCT. NOV. DEC. MONTHS FORECAST ACTUAL4000 WEEKLYWEEKLY PEAK GENERATION HISTOGRAM PEAK TOTAL MW GENERATION JANUARY-DECEMBER 2006, CHART 28 (SEE TABLE13A) JANUARY-DECEMBER 2007, CHART 31 (SEE TABLE16) 40003500SYSTEM GENERATION IN MW 35003000 SYSTEM GENERATION IN MW 30002500 25002000 20001500 15001000 1000 500 500 0 0 1 JAN. 2 FEB. 3 MAR. 4 APR. 5 MAY. 6 JUN. 7 JUL. AUG. 8 SEP. 9 OCT. 10 NOV. 11 DEC. 12 MONTHS MONTHS Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 87
  • KAINJI P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 32 800USABLE GENERATING CAPACITY IN 700 600 500 MW 400 300 200 100 0 G T V Y EC N R PR L P B N C JU A O SE JA A FE JU U O D A M N M A MONTHS INSTALLED CAPACITY. DAILY CAPACITY JEBBA P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 33 700 :USABLE GENERATING CAPACITY IN 600 500 400 MW 300 200 100 0 N G R PR N L Y P V B EC T JU C SE A O JA A FE JU U O A M D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 88
  • SHIRORO P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 34 700:USABLE GENERATING CAPACITY IN 600 500 400 MW 300 200 100 0 G N PR R Y V EC L T B N P JU C A O JA SE A FE JU U O A M D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY EGBIN P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 35 1500 :USABLE GENERATING CAPACITY IN MW 1000 500 0 G Y N R PR P V B N EC L T JU C A O SE JA A JU FE U O M A D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 89
  • DELTA P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 36 1000:USABLE GENERATING CAPACITY IN 900 800 700 600 MW. 500 400 300 200 100 0 Y PR N R G T EC L B N P V A C JU JA A O SE JU U FE M O A M D A N MONTHS INSTALLED CAPACITY. DAILY CAPACITY AFAM P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 37 700 :USABLE GENERATING CAPACITY IN MW 600 500 400 300 200 100 0 Y PR N R G T EC L B N P V A C JU JA A O SE JU U FE M O A M D A N MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 90
  • SAPELE P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 38 1200:USABLE GENERATING CAPACITY IN MW 1000 800 600 400 200 0 G O 0 N PR AY L T N EC B AR P V JU C SE O JA FE JU U M A D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY OMOTOSHO P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 39 400:USABLE GENERATING CAPACITY IN MW 350 300 250 200 150 100 50 0 Y R PR EC N G L P V B N T JU C A O SE JA A FE JU U O M A D M N A MONTHS DAILY CAPACITY INSTALLED CAPACITY. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 91
  • AES USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 40 350 300 :USABLE GENERATING CAPACITY IN MW 250 200 150 100 50 0 N G R PR N L Y P V B EC T JU C SE A O JA A FE JU U O A M D M N A MONTHS INSTALLED CAPACITY. INSTALLED CAPACITY. OKPAI USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 41 600:USABLE GENERATING CAPACITY IN MW 500 400 300 200 100 0 N PR G Y R B L T P V N EC A JU C O SE JA A U FE JU O M A M D A N MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 92
  • GEREGU P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 42 450:USABLE GENERATING CAPACITY IN MW 400 350 300 250 200 150 100 50 0 R Y G N R B N L C P V T JU A C NO A AP SE JA FE DE JU AU O M M MONTHS INSTALLED CAPACITY. DAILY CAPACITY OMOTOSHO P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 43 400 350 :USABLE GENERATING CAPACITY IN MW 300 250 200 150 100 50 0 G N R R Y N C P V L CT B JU A NO JA AP SE A JU DE AU FE O M M MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 93
  • OMOKU P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 44 300 :USABLE GENERATING CAPACITY IN MW 250 200 150 100 50 0 Y R PR EC N G L P V N B T JU C A O SE JA A FE JU U O M A D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY AJAOKUTA USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 45 120;USABLE GENERATING CAPACITY IN MW 100 80 60 40 20 0 N B R P PR N EC Y L T V G JU C A SE O JA A JU FE U O A M D M N A MONTHS INSTALLED CAPACITY. DAILY CAPACITY Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 94
  • PAPALANTO P.S. USABLE GEN. CAPACITY SPECTOGRAPH JANUARY-DECEMBER 2007 CHART 46 400 350 300 250 200 150 100 50 0 N G N R PR L V Y P EC B T JU C SE A O JA A FE JU U O A M D M N A INSTALLED CAPACITY. DAILY CAPACITY DAILY TOTAL GRID GENERATION AVAILABILITY STATUS JANUARY-DECEMBER 2007 CHART 47 12000 10000GENERATION CAPACITY 8000 6000 4000 2000 0 N PR G Y R B L T P V O 0 N EC A JU C O SE JA A U FE JU M A M D A N MONTHS ADQ.GEN GEN.STATUS UTILIZABLE Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 95
  • APPENDIX 2.0GRID REINFORCEMENT AND REHABILITATION RECORDS FOR 2007. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 96
  • GRID REINFORCEMENT AND REHABILITATION RECORDS FOR 20071 13/01/07 Akangba T/S 150MVA 330/132kV transformer 5T4A was restored following the replacement of the burnt Red phase clamp on the lightening arrester. The grid security was improved.2 15/01/07 Jebba P/S 330kV Circuit Breaker No. T5A main CB to 2G5 was declared available for service sequel to the sealing of oil leakage on the Circuit Breaker. The system protection was enhanced.3 18/01/07 Corroded glass insulators to composite type on tower No. 351 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W) were replaced. This strengthened the grid.4 22/01/07 P.H. Main T/S 60MVA 132/33kV transformer T3A was energized from Omoku P/S with an initial load of 38MW. This enhanced the grid reliability.5 23/01/07 Corroded glass insulators to composite type on tower No. 282 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W) were replaced. Grid reliability improved.6 25/01/07 Broken glass insulator was changed with silicon composite type on tower No 824 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). The network was reinforced.7 26/01/07 Broken glass insulator was changed with silicon composite type on tower No 286 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). The network was reinforced.8 2801/07 Maryland T.S. 30/40MVA 132/33kV transformer T2 was restored having corrected the current and voltage imbalance on the secondary side. Transformation capacity was boosted.9 29/01/07 Ilorin T/S 60MVA 132/33kV transformer T1A secondary OCB was restored having replaced a burnt yellow phase contactor and carbonized oil. This increased the grid transformation.10 01/02/07 Ibadan North T.S. 60MVA 132/33kV transformer T2 was restored following the replacement of the shattered Blue Phase interrupter head. This boosted the grid transformation capacity.11 07/02/07 Ikeja West/Sakete 330KV line was energized from Ikeja West.12 12/02/07 Replacement of the vandalized optic fibre cable along Jebba/Shiroro 330 kV line cct J3R.13 13/02/07 A corroded glass insulator was changed to composite type on tower No. 327 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 97
  • in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). This raised grid security.14 15/02/07 There was replacement of corroded glass insulators with composite type on tower No. 378 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). This strengthened the grid reliability.15 15/02/07 Akangba T/S 90MVA 330/132/13.8kV transformer 5T2B was restored after the oil regeneration of the main transformer and its grounding transformer.16 20/02/07 Geregu GT13 was synchronized to the grid and loaded up to 15MW.17 28/02/07 Maryland/Ikorodu 132kV line 1 was restored subsequent to the replacement of the analogue distance protection relay with a digital distance protection relay at Maryland T/S.18 04/03/07 Egbin/Aja 330kV line 2 (CCT. N4J) was restored after replacing the shattered Red Phase CT on CB 52-15 at Egbin T.S. end.19 07/03/07 Benin T/S 6R1 75MX reactor was declared available after maintenance crew sealed leaking points.20 09/03/07 Egbin/Aja 330kV CB 52-16 North bus breaker CTs 25 & 26 were replaced with new sets of CTs. Equipment protection was reinforced.21 12/03/07 Egbin/Aja 330kV line 1 (CCT. N3J) was restored after the replacement of shattered CTs No. 25 and 26.22 14/03/07 Corroded glass insulators was replaced with composite type on tower No. 301 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). This strengthened the grid.23 14/03/07 Shiroro G.S. 411G4 was declared available after annual maintenance on the unit and 72 hours reliability test.24 19/03/07 Corroded glass insulators was replaced with composite type on tower No. 308 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). This strengthened the grid reliability.25 20/03/07 Vandalized optic fibre optic fibre cable along the sky wire of 330kV Osogbo/Ayede line (CCT. H2A) CB were re-strung at both ends. Improved communication and SCADA data acquisition resulted.26 21/03/07 Three new sets of CTs were installed on Jebba/Osogbo 330kV line 3 (C CCT. J3H) at Osogbo T.S end.27 22/03/07 Omuaran T.S. 30MVA 132/33kV transformer T1 was restored after bleeding the transformer of moisture.28 22/03/07 Corroded glass insulators were changed to composite type on tower No. 515 on Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). Grid security was enhanced.29 22/03/07 A control fault locator equipment was installed on circuits H1W, H7B and Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 98
  • H2A at Osogbo T/S.30 22/03/07 Ikeja West/Akangba 330kV line 3 (CCT. W3L) was restored back to service having replaced broken glass disk insulators on the line’s Yellow Phase with silicon composite type on tower #556.31 22/03/07 Ikeja west/Akangba 330kV line (CCT. W3L) was restored after the LMD replaced the disc insulator with silicon composite type on tower No. 538.32 27/03/07 Corroded glass insulators was replaced with composite type on tower No. 571 in Benin/Ikeja West 330kV lines 1 & 2 (CCTs. B5W and B6W). Grid security was enhanced.33 27/03/07 Alagbon/Akoka 132kV line was restored after burnt Blue Phase lightning arrester at Akoka T.S. was replaced.34 30/03/07 Kaduna/Zaria 132kV line was closed after restringing cut conductors between towers 425 to 429.35 02/04/07 Alaoji T/S 150MVA 330/132/33kV tranformer T2A primary breaker was restored back to service following repair of the faulty hydraulic system.36 04/04/07 Aba T/S 30MVA 132/33kV Mobitra primary breaker was restored after maintenance crew had amended punctured Mobitra 33kV secondary yellow phase up riser cable.37 11/0407 Shiroro 150MVA 330/132/33kV transformer T2 was restored after the defective 1 No Yellow Phase secondary lightening arrester was replaced.38 17/04/07 Jos T.S. 60MVA 132/33kV transformer T3 was welded, regasketed and painted by the maintenance crew.39 24/04/07 Delta/Benin 132kV line 2 was closed after the burnt relay on the control board was changed.40 26/04/07 Kano/Dutse/Azare 132kV line was formerly commissioned by the President of the Federal Republic of Nigeria.41 28/04/07 Zaria/Kano 132kV line was restored after maintenance crew replaced shattered insulator red phase on tower No. 535.42 09/05/07 Damboa T.S. was restored after the maintenance crew repaired the blown off Station Roof which flooded the station.43 13/05/07 Mando T/S 60MVA 132/33kV transformer T2 was resotred after replacing the shattered red phase secondary CT.44 14/05/07 Alimoso 30MVA 132/33kV T3 was restored after the yellow phase lightning arrester on the primary side was replaced.45 17/05/07 Egbin/Aja 330KV line 4 (CCT. N4J) was restored after the replacement of 3 phases. Faulty CTs with new one46 19/05/07 Vandalized optic fibre cable on tower No. 471 along Jebba/Shiroro 330kV line 1 (CCT. J7R) was restrung. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 99
  • 47 24/05/07 Common primary CB to Ikeja West T/S 2x150MVA 330/132/33kV transformers T2A & T2B was restored after a successful rehabilitation work on the CB.48 29/05/07 Benin/Ikeja West 330kV lines 1 (CCT. B5W) was restored at both ends following the re-tension of its blue phase conductor at Omotosho T/S.49 29/05/07 Aja 60MVA 132/33kV T2 was restored after a new 33kV secondary CB was installed for the transformer.50 30/05/07 Akure 60MVA 132/33kV T3A was restored after a burnt trip coil of the secondary CB was replaced with a new one.51 31/05/07 Benin/Ikeja West 330kV lines 1 and 2 (CCTs. B5W and B6W) tie breaker at Ikeja West was restored after sealing of SF6 gas leakage.52 01/06/07 Effunrun T/S 60MVA 132/33kV xformer T22 was restored to service after the termination of the secondary conductor which pulled out from the Blue phase bushing clamp53 01/06/07 Ikorodu/Shagamu Cement Factory 132kV line was restored up to Cement factory terminal after re-erecting the collapsed pole along the line.54 03/06/07 Amuwo 30MVA 132/33kV T2 was restored after the replacement of a broken pin linking 2 mechanisms in the primary breaker of the transformer.55 07/06/07 Omotosho P.S. 330kV T.S. was energized from the grid.56 08/06/07 Alimosho T.S. 30MVA 132/33kV transformer T1 was restored after the punctured secondary cable Yellow Phase was amended.57 08/06/07 Osogbo/Offa/Omuaran/Ilorin 132kV line was restored back after reconnection of the cut Blue Phase conductor between towers #91 and #92.58 14/06/07 Omotoso P/S GT1 was synchronized to the grid with initial load of 5MW.59 17/06/07 Akangba T/S 150MVA 330/132/33kV transformer 5T4A was restored having replaced secondary Blue phase lightning arrester and carried out test on the transformer.60 17/06/07 Birnin-Kebbi/Niamey 132kV line was restored after amending cut sky wire on tower No. 430 and 434.61 21/06/07 Itu/Calabar 132kV line was restored after amending the cut conductor along the line.62 24/06/07 Alaoji/Owerri/Ahoada/Yenegoa 132kV line 2 was restored after the linesmen restrung the vandalized portion.63 25/06/07 Alaoji/Owerri/Ahoada/Yenegoa 132kV line 1 was restored after the linesmen restrung the vandalized portion.65 12/07/07 The burnt Osogbo/Benin 330kV line (CCT. H7B) bus isolator was replaced with new one. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 100
  • 66 18/07/07 Alimoso T/S 30MVA 132/33kV transformer T1 was restored after the transformer secondary Yellow phase burnt cable was changed.67 19/07/07 Akoka T/S 45MVA 132/33/11kV transformer TR1 was restored after maintenance crew/Environmental Technology Ltd. had connected regeneration/purification equipment to the transformer for filtration68 23/07/07 Omotosho P/S GT2 was tied.69 03/08/07 Benin/Ikeja West 330kV lines 2 (CCT. B6W) was restored at both ends after restringing cut sky wire on tower No 409 & 41070 03/08/07 Akure T/S 60MVA 132/33kV transformer T3A primary CB ‘s burnt Blue phase differential relay was changed to new one.71 10/08/07 Shiroro 330kV CB 3502 – Defective 150MVA transformer T1 main breaker was replaced with a new one.72 12/08/07 Maiduguri T1 45MVA 132/33kV transformer T2 was restored after faulty hydraulic oil pump motor had been changed with new one by maintenance crew.74 24/08/07 Shiroro Unit 411G3 was declared available after monthly inspection and elimination of leakages from the pressure switch in the actuator cabinet and inspection of shaft seal assembly.75 27/08/07 Osogbo T.S. 150MVA 330/132/33kV transformer 4T1 secondary breaker was restored after maintenance crew replaced the burnt transformer secondary Yellow Phase conductor and topped the low SF6 gas pressure on the breaker.76 29/08/07 Ikorodu 60MVA 132/33kV was restored after 3 No new secondary CTs were installed to replace the observed smoking ones.77 29/08/07 At Benin T.S. work completed on Benin/Ikeja West 330kV lines 1 (CCT. B5W) after the maintenance crew replaced shattered yellow phase pole of the breaker with another from the spare 330kV bus coupler 1 CB .78 30/08/07 Suleja/Minna 132kV line 2 was restored after restringing vandalised blue phase conductor between towers 248 to 251.79 30/08/07 Egbin P.S ST1 330KV CB (52-6) was restored after the three phases C.Ts were replaced with new ones.80 07/09/07 Afam P/S GT17 was tied on test run with 30MW only.81 07/09/07 Osogbo T/S 90MVA 330/132/13.8kV transformer 4T2 was restored back to service after the primary CB problem was rectified.82 08/09/07 Ikorodu T.S. 60MVA 132/33kV transformer T1 was restored after the secondary Blue Phase CT was replaced.83 13/09/07 Osogbo/Benin 330kV line (CCT. H7B) was restored at both ends after 3 Nos leaking, including shattered blue phase CT’s were replaced at Benin T.S. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 101
  • 84 24/09/07 Shiroro 411G2 was tied after the completion of meggering of 411G3.85 26/09/07 Ikeja West/Agbara 132kV line 2 was closed after repairing the detached conductor on tower No. 153.86 01/10/07 Ayede T.S 30MVA 132/33kV transformer T2 primary breaker was restored after the punctured up-riser cable was replaced with new one on the secondary transformer breaker.87 04/10/07 Ikeja West/Oworonsoki 132kV line 1 was restored back to service after a detatched jumper on tower NO.29 was restrung.88 05/10/07 Shiroro 411G4 was declared available after the faulty cooling water flow meter flapper was rectified.89 08/10/07 Kainji/Jebba 330kV line 2 (CCT. K2J) was restored after replacing the burnt gas pressure coil.90 09/10/07 Papalanto T/S T3 30MVA 132/33kV transformer was restored back to service having repaired the burnt the secondary upriser cable.91 10/10/07 Abakaliki T/S 15MVA 132/33kV transformer T2 which was commissioned on 1st August 2007 was placed on load.92 18/10/07 Broken insulators on Zaria/Kano 132kV line at Zaria tower Nos 423, 426, 429, 430, 434 & 435 were replaced with new ones.93 20/10/07 Ikorodu T/S 60MVA 132/33kV transformer T1 was restored after the blue phase secondary bus isolator contact was replaced with new one.94 31/10/07 Gombe T/S 150MVA 330/132kV transformer T1A/50MX reactor R1 common primary breaker was restored after the maintenance crew had sealed SF6 gas leakage on the breaker.95 09/11/07 Ojo T.S. 30MVA 132/33kV transformer T2 secondary breaker was restored after the breaker mechanism was replaced.96 09/11/07 Papalanto T.S. 15MVA 132/33kV transformer T2 was restored after the leakage point on both primary Blue Phase and secondary yellow Phase bushings were sealed.97 10/11/07 Jebba 2G1 was tied after the purification of the unit Governor System Oil.98 12/11/07 Omotosho P/S GT5 was tied on test run.99 15/11/07 Jebba G.S. 2G1 was declared available after replacement of the unit defective mechanical over speed valve with a new one.100 15/11/07 Kainji/Jebba 330kV line 2 (CCT. K2J) was closed at Kainji end after maintenance crew had affected repairs on the line breaker compressor relief valve.101 19/11/07 Benin/Onitsha 330kV line (CCT. B1T) was restored after the replacement of the burnt red phase CVT at Onitsha T/S. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 102
  • 102 23/11/07 Broken insulators on towers 129, 132 & 177 and 180. Mando/Zaria/Funtua/Talata-Mafara 132kV lines were changed.103 04/12/07 Maintenance crew/Siemens contractors at Jos T/S carried overhauling of the 330kV tie breaker (CB2) breaker.104 05/12/07 Yandev T/S 45MVA 132/33kV Mobitra T3 was restored after replacing the secondary CB with new one.105 06/12/07 Papalanto P.S. GT3 was tied to the Grid with initial load of 1.7MW106 08/12/07 Papalanto P/S GT2 was synchronized to the grid system with initial load of 4.7MW.107 12/12/07 Ojo T.S. 30MVA 132/33kV transformer T1 was restored after the completion of oil filtration on the transformer.108 14/12/07 Papalanto P/S GT5 was synchronized to the grid system.109 15/12/07 Papalanto GT1 was tied with initial load of 4.6MW.110 26/12/07 Apo/Keffi/Akwanga 132kV line which was vandalised was energized ACCIDENTS AND MISHAPS RECORDS FOR 20071 26/01/07 Alaoji/Owerri 132kV lines 1 & 2 were vandalised between towers Nos. 81 and 84 at Ngou Kpilla village.2 11/02/07 Optic fibre cable was vandalized along Jebba/Shiroro 330kV line (CCT. J3R).3 02/02/07 There was fire on Jebba/Osogbo 330kV line 3 (CCT. J3H) blue phase Current Transformer at Osogbo 330kV T/S4 03/03/07 Egbin/Aja 330kV line 2 (CCT. N4J) Red Phase Current Transformer on Circuit Breaker 52-15 shattered at Egbin T.S. end.5 02/05/07 Mando T/S, Kaduna town 2 132kV Red phase Current Transformer on the secondary side of the 60MVA 132/33kV shattered.6 05/05/07 Delta T/S 45MVA 132/33/11kV transformer T1 and 30MVA 132/33kV transformer T2 three phases pole got shattered.7 06/05/07 Damboa 132kV T/S Control Room roof was reported blown off by storm leading to flooding of the Control Room. There by there was power interruption in the station.8 12/05/07 Mando T/S 60MVA 132/33kV transformer T2 red phase Current Transformer shattered.9 18/05/07 Optic fibre cable on Jebba/Shiroro 330kV line 1 (CCT. J7R) was vandalized at tower No. 471.10 22/05/07 A pole collapsed on Korodu/Shagamu Cement Factory 132kV line. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 103
  • 11 23/05/07 Jebba/Osogbo 330kV line 1 (CCT. J1H) sky wire between towers 146 and 147 was vandalized, cutting off the optic fibre and Man Machine Interface(MMI) operations at NCC.12 26/05/07 Aja T.S. TR4 150MVA 330/132kV transformer/Alagbon 132kV line 2/TR2 60MVA 132/33kV transformer Yellow Phase secondary CB interrupter head got shattered, caught fire and tripped.13 26/05/07 Aja 60MVA 132/33kV T2 yellow phase interrupter head of the secondary CB shattered.14 29/05/07 Akure T.S. 60MVA 132/33kV transformer T3A primary breaker tripped on differential relay C and the trip coil of the secondary CB got burnt.15 20/06/07 Blue phase CVT of Itu/Uyo/Calabar 132kV line exploded at Itu T/S.16 23/06/07 Alaoji/Owerri 132kV lines 1 & 2 were vandalized between towers 163 and 165. Line 1 was vandalized on the Blue phase while line 2 was vandalized on the Red phase.17 12/07/07 Ikeja West T/S 150MVA 330/132/33kV transformer T1B primary red phase lightning arrester and the 75MX reactor blue phase lightning arrester were observed shattered.18 12/07/07 Benin T/S, Osogbo/Benin 330kV line (CCT. H7B) bus isolator was burnt.19 19/08/07 Alaoji/Owerri 132kV line 1, the three phases connecting rods in the breaker were broken. Owerri T.S, Yeneguoa T.S. and Ahoada 132kV T.S. were affected.20 28/08/07 Suleja/Minna 132kV line 2 blue phase conductor between towers 248 to 251 was vandalized.21 10/09/07 Owerri/Ahoada 132kV line 1, Red phase Current Transformer at Ahoada T/S exploded.22 18/10/07 Sky wire between tower Nos 307 – 545 & 544 were vandalized along Osogbo/Ikeja West 330kV line (CCT. H1W).23 11/11/07 Effurun T/S 60MVA 132/33kV transformer T23, 33KV Current Transformer red phase of the earthing transformer got burnt and the red phase conductor between the transformer and its earthing transformer cut.24 23/11/07 A Tree fell on the Osogbo/Benin 330kV line (CCT. H7B) between towers 409 and 410.25 21/12/07 Minna T.S. 30MVA 132/33kV transformer T1 Yellow Phase secondary isolator exploded and shattered.26 24/12/07 Apo/Akwanga/Keffi 132kV line reported the vandalization of Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 104
  • Yellow and Blue Phases around Yaya Dagara between towers 57 & 59, a distance of about 34.7km from Abuja.Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 105
  • APPENDIX 3.0SYSTEM DISTURBANCES, ACCIDENTS AND MISHAPS RECORDSFOR JANUARY TO DECEMBER 2007.SECTION A: SYSTEM DISTURBANCESSECTION B: ACCIDENTS AND MISHAPS RECORDS. Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 106
  • TABLE 18 SUMMARY OF SYSTEM DISTURBANCES. JANUARY - DECEMBER 2007. PARTIAL GRID COLLAPSE TOTAL GRID COLLAPSE DISTURBANCES WITH DISTURBANCES CAUSED DISTURBANCES CAUSED TOTAL BY GEN. FAULTS BY TRANS. FAULTS DISTURBANCES DISTURBANCES UNDETERMINABLE CAUSES YEAR NO. OF ACTUAL % OF ACTUAL % OF GEN. TRX. GEN. TRX. TOTAL PARTIAL %(JAN-DEC.) DISTURB. NO. TOTAL. NO. TOTAL. CAUSED CAUSED TOTAL CAUSED CAUSED TOTAL COLLAPSE COLLAPSE TOTAL TOTAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 2007 27 3 11.11% 24 88.89% 1 7 9 2 16 18 0 0 0 0.00% 2006 30 8 26.67% 22 73.33% 2 8 10 6 14 20 0 0 0 0.00% 2005 36 15 41.67% 21 58.33% 4 11 15 11 10 21 0 0 0 0.00% 2004 52 20 38.46% 32 61.54% 7 23 30 13 9 22 0 0 0 0.00% 2003 53 14 26.42% 39 73.58% 9 30 39 5 9 14 0 0 0 0.00% 2002 41 19 46.34% 22 53.66% 18 14 32 1 8 9 0 0 0 0.00% 2001 19 9 47.37% 10 52.63% 1 4 5 8 6 14 0 0 0 0.00% 2000 11 2 18.18% 9 81.82% 0 6 6 2 3 5 0 0 0 0.00% 1999 9 2 22.22% 7 77.78% 1 4 5 1 3 4 0 0 0 0.00% 1998 18 2 11.11% 16 88.89% 2 11 13 0 5 5 0 0 0 0.00% 107 1997 20 0 0.00% 20 100.00% 0 13 13 0 7 7 0 0 0 0.00% 1996 10 3 30.00% 7 70.00% 2 6 8 0 2 2 0 0 0 0.00% 1995 11 0 0.00% 11 100.00% 0 10 10 0 1 1 0 0 0 0.00% 1994 5 4 80.00% 1 20.00% 1 3 4 0 2 2 0 0 0 0.00% 1993 19 0 0.00% 19 100.00% 0 14 14 0 5 5 0 0 0 0.00% 1992 1 0 0.00% 1 100.00% 0 1 1 0 0 0 0 0 0 0.00% 1991 6 1 16.67% 5 83.33% 0 1 1 1 4 5 0 0 0 0.00% 1990 14 11 78.57% 3 21.43% 0 0 0 11 3 14 0 0 0 0.00% 1989 16 5 31.25% 11 68.75% 0 6 6 5 5 10 0 0 0 0.00% 1988 22 9 40.91% 12 54.55% 3 5 8 6 7 13 1 0 1 4.55% 1987 33 9 27.27% 24 72.73% 0 13 13 9 11 20 0 0 0 0.00%
  • TABLE 19A SUMMARY OF SYSTEM DISTURBANCES OF INTEGRATED GRID OPERATIONS FOR 2007 TYPE OF DISTURBANCE IN TIME (HRS) DURATION DATE/ LOAD LOST THE GRIDS/N DAY OF LOST CAUSE/REMARKS MONTH (MW) Disturbance Restoration of (HOURS) TOTAL PARTIAL Occurred Supply THE TRIPPING OF THE FOLLOWING DELTA 4 330 CIRCUIT BREAKERS: (I) TIE_5 CB, (ii) Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 1 27/01/07 SAT 12:35 13:53 1.30 2427.5 X GTr_1 CB AND (iii) GTr_4 CB RESULTED TO THE LOSS OF GT15, GT18 AND GT20, (iv) DELTA/BENIN 330KV (CCT. G3B) LINE CB AND DELTA/ALADJA 300KV (CCT. G1W) LINE CB. 2 07/02/07 WED 13:26 14:00 0.57 2742.2 X COMMISSIONING TEST ON TERMINAL EQUIPMENT THE SHATTERING OF CURRENT TRANSFORMER (CT) No. 16 RED PHASE OF 330KV BAY 11 ON 3 13/02/07 TUES 19:44 20:20 0.60 2484.7 X DIAMETER 3, AT EGBIN T.S. THIS TRIGGERED THE OPERATION OF THE EGBIN BUS ZONE PROTECTION RELAY. 4 02/03/07 FRI 21:30 22:31 1.02 2328.9 X THE EXPLOSION OF THE BUS COUPLER CT AT BENIN T/S OVERLOADING SUSPECTED AFTER THE RESTORATION OF BENIN/ONITSHA 330KV LINE (CCT. 5 04/03/07 SUN 15:02 15:46 0.73 1843.4 X B1T) THAT TRIPPED EARLIER. THE TRIPPING OF CCT B1T ON DISTANCE PROTECTION RELAY AT ONITSHA END, REJECTING 6 15/03/07 THURS 08:07 09:15 1.13 2037.0 X 179MW POWER FLOW TO BENIN. 108 THE TRIPPING OF JEBBA/OSOGBO 330KV LINES 1 & 2 (CCTs J1H & J2H); OSOGBO/IKEJA WEST 7 16/03/07 FRI 19:10 19:40 0.50 1655.0 X 330KV LINE (CCT H1W) AND OSOGBO/BENIN 33OKV LINE (CCT H7B); AND TRANSFORMERS 4T1 & 4T2 330KV CB AT OSOGBO T/S. 8 18/03/07 SUN 21:40 22:05 0.42 2587.0 X THE TRIPPING OF EGBIN/IKEJA WEST 330KV LINES 1 & 2 (CCTS N7W & N8W) AT BOTH ENDS (I) THE TRIPPING OF EGBIN/IKEJA WEST 330KV LINE 2, EGBIN/AJA 330KV LINE 3 AND 9 27/03/07 TUES 15:50 16:28 0.63 2386.7 X EGBIN/IKORODU 132KV LINES 5 AND EGBIN/IKORODU 132KV LINES 5 AND 6.AND 6. THE TRIPPING OF EGBIN/IKEJA WEST LINE 2 (CCT.N8W), EGBIN/AJA 330KV LINE 1(CCT.N3J)10 28/03/07 WED 04:12 04:23 2417.6 X AND EGBIN/IKORODU 132KV LINE 5 THE TRIPPING OF OSOGBO/BENIN 330KV LINE (CCT. H7B) AT OSOGBO END ONLY AND11 31/03/07 SAT 13:25 13:47 0.37 2330.1 X BENIN/IKEJA WEST 330KV LINE (CCT. B6W) AT IKEJA WEST END ONLY THE TRIPPING OF DELTA/BENIN 330KV LINE AT DELTA P.S (CCT.G3B) AND SAPELE/BENIN12 01/04/07 SUN 11:25 11:57 0.53 2150.2 X 330KV LINES 1 AND 2 (CCTS.S3B & S4B) AT SAPELE END. LOAD LOSS 258MW
  • TABLE 19B SUMMARY OF SYSTEM DISTURBANCES OF INTEGRATED GRID OPERATIONS FOR 2007 TYPE OF DISTURBANCE IN TIME (HRS) DURATION LOAD DATE/ THE GRIDS/N DAY OF LOST LOST CAUSE/REMARKS MONTH Disturbance Restoration of (HOURS) (MW) TOTAL PARTIAL Occurred Supply13 03/04/07 TUES 06:22 07:04 0.70 2211.9 X THE TRIPPING OF EGBIN/IKEJA WEST 330KV LINE (CCT. N8W) AT EGBIN T.S. IN THE PROCESS OF REDUCING EGBIN/AES GENERATION FROM 500MW TO 300MW AS Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo14 07/04/07 SAT 16:35 17:16 0.68 2102.5 X INSTRUCTED BY NGC, EGBIN UNIT ST1 TRIPPED CAUSING FREQUENCY DECAY WHICH RESULTED TO SYSTEM COLLAPSE.15 10/4/07 TUES 18:46 19:15 0.48 2119.4 X GRID OVERLOAD.16 01/06/07 FRI 10:32 10:54 0.37 1963.2 X THE TRIPPING OF OSOGBO/IKEJA WEST 330KV LINE (CCT. H1W) AT BOTH ENDS17 03/07/07 TUES 14:35 15:13 0.63 2327.9 X THE TRIPPING OF CCTs. H1W, H2A AND H7B . (1) THE TRIPPING OF OSOGBO/IKEJA WEST 330kV LINE CCT. H1W AT IKEJA WEST END18 04/07/07 WED 06:27 06:47 0.33 2335.1 X ONLY. (2) THE TRIPPING OF EGBIN/IKEJA THE TRIPPING OF OKAPI/ONITSHA 330kV LINES 1 & 2 (CCTs. K1T & K2T) ON OVER19 05/07/07 THURS 15:50 16:13 0.38 2277.6 X VOLTAGE RESULTED TO DECLINE OF GRID FREQUENCY WHICH LEAD TO THE TRIPPING OF EGBIN ST1 & ST5 THE TRIPPING OF BENIN/ONITSHA 330KV LINE (CCT. B1T) LINE AT ONITSHA END20 09/07/07 MON 13:35 14:02 0.45 1918.3 X ONLY. 109 (i) THE TRIPPING OF BENIN/IKEJA WEST 330KV LINE (CCT. B6W) AT BOTH END21 12/7/07 THURS 15:29 20:05 4.60 1902.5 X (ii) THE BURNING OF CCT. H7B BUS ISOLATOR WHICH LED TO THE TRIPPING OF OSOGBO/BENIN 330KV LINE (CCT. H7B) AT BOTH END (I) THE TRIPPINGS OF BENIN/IKEJA WEST 330KV LINE (CCT. B6W) AT BOTH ENDS22 14/07/07 SAT 12:23 13:04 0.68 1077.0 X (II) THE TRIPPINGS OF OSOGBO/BENIN 330KV LINE (CCT. H7B) AT BOTH ENDS.23 25/08/07 SAT 13:34 18:27 4.88 2723.7 X THE TRIPPING OF BENIN/ONITSHA 330KV LINE (CCT. B1T) AT BOTH END THE TRIPPING OF OSOGBO/BENIN 330KV LINE (CCT H7B) AS A RESULT OF THE24 07/09/07 FRI 19:34 20:05 0.52 3205.5 X EXPLOSION AND BURNING OF THE BLUE PHASE CT AT BENIN END THE TRIPPING OF BENIN/SAPELE 330KV LINES 1 & 2 (CCTS S3B & S4B)25 06/10/07 SAT 18:33 19:20 0.78 3204.9 X SIMULTANEOUSLY, AND BENIN/DELTA 330KV LINE (CCT G3B ). THE EXPLOSION OF THE BENIN/IKEJA WEST 330KV (CCT. B5W) CB RED PHASE POLE26 20/10/07 SAT 22:27 23:56 1.48 2383.8 X AND THE LINE CT BLUE PHASE AT BENIN T.S. RESULTING TO THE TRIPPING OF THE BUS ZONE PROTECTION. THE EXPLOSION OF THE BENIN/IKEJA WEST 330KV (CCT. B5W) CB RED PHASE POLE27 03/11/07 SAT 15:23 16:37 1.23 2460.2 X AND THE LINE CT BLUE PHASE AT BENIN T.S. RESULTING TO THE TRIPPING OF THE BUS ZONE PROTECTION.
  • TABLE 19C. SUMMARY OF SYSTEM DISTURBANCES OF INTEGRATED GRID OPERATIONS FOR 2007OCCURRENCE OF SYSTEM COLLAPSES FOR 2007 ON DAILY BASES SINGLE GRID SINGLE GRID DAY TOTAL TOTAL PARTIAL MON 1 0 1 TUE 4 1 5 WED 3 0 3 THUR 3 0 3 FRI 1 3 4 SAT 4 4 8 SUN 2 1 3 TOTAL 18 9 27OCCURRENCE OF SYSTEM COLLAPSES FOR 2007 ON MONTHLY BASES SINGLE GRID SINGLE GRID DAY TOTAL TOTAL PARTIAL JAN 1 0 1 FEB 2 0 2 MAR 5 3 8 APR 3 1 4 MAY 0 0 0 JUN 0 1 1 JUL 5 1 6 AUG 1 0 1 SEP 0 1 1 OCT 0 2 2 NOV 1 0 1 DEC 0 0 0 TOTAL 18 9 27 Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 110
  • GRAPHICAL REPRESENTATION OF SYSTEM COLAPSES 2007 (CHART 48) 4.5 4 NO OF SYSTEM COLLAPSES 3.5 3 2.5 2 1.5 1 0.5 0 MON TUE WED THUR FRI SAT SUN DAYS SINGLE GRID TOTAL GRAPHICAL REPRESENTATION OF SYSTEM COLLAPSES 2007 ( CHART 49) 6NO OF SYSTEM COLLAPSES 5 4 3 2 1 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MONTHS SINGLE GRID TOTAL Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 111
  • THE SUMMARY OF SYSTEM DISTURBANCES IN YEAR 2007 JANUARY - DECEMBER 2007 (CHART 50) 30 27 24 21 NO. OF COLLAPSE 18 15 12 9 6 3 0 NO. OF TOTAL COLLAPSE IN NO. OF PARTIAL COLLAPSE IN NO. OF SYSTEM DISTURBANCES SINGLE GRID = 18 SINGLE GRID = 9 IN THE GRID = 27 TYPE OF COLLAPSE THE LOAD LOSS DUE TO SYSTEM DISTURBANCES 2007 ON MONTHLY BASES ( CHART 51) 13000 12000 11000 10000THE AVERAGE LOAD LOSS (MW) 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC THE MONTHS OF THE YEAR Generation and Transmission Grid Operations-2007-National Control Centre, Osogbo 112