POWER HOLDING COMPANY OF NIGERIA PLCNATIONAL CONTROL      CENTRE     OSOGBO   GENERATION       AND  TRANSMISSION GRID OPER...
TABLE OF CONTENTS                                                                               PAGES   INTRODUCTION      ...
NO.                   LIST OF TABLES                                                PAGE1A.   HYDROLOGICAL SUMMARY        ...
NO.                        CHARTS                                                          PAGE1.    KAINJI AVERAGE MONTHL...
NO.                    CHARTS                                                     PAGE 26    REGIONAL ENERGY AVAILABLE FOR...
lNTRODUCTIONThis Technical Report, an annual publication of Power Holding Company Nigeria Plc(PHCN), covered the National ...
1.1      HYDROLOGY AND LAKE OPERATIONS1.1.1.   Kainji LakeThe average computed inflow of the 2006/2007 black flood yield i...
TABLE 1A: HYDROLOGICAL SUMMARY. JANUARY - DECEMBER 2007             AVE.TURB.DISCH.               AVE.SPILLAGE        STAT...
KAINJI AVE.MONTHLY TOT. DISCHARGE & INFLOW                                                                                ...
The fast draw down was as a result of National demand as the gas supply to the ThermalPower Stations was unstable. To main...
TABLE1B: PLAN/ACTUAL COMP. AVE. INFLOW AND AVE. TURB. DISCH. (CUB.M/SEC). JANUARY - DECEMBER 2007.                     KAI...
Overall Kainji MW availability was better (28.2%) than the figure of the previous year(see chart 1&2)1.1.2   Jebba LakeAt ...
JEBBA AVE. MONTHLY TOTAL DISCHARGE & INFLOW                                                                               ...
SHIRORO AV. MONTHLY TOT. DISCHARGE & INFLOW                                                                       JANUARY-...
The draw down plan of the Shiroro Lake between March and August 2007 was agreedupon at the Joint Operations/Generation Pla...
1.2.    THERMAL GENERATION1.20.   GENERATION AVAILABILITYIn table 2, the average Power(MW) availability was depicted. Anal...
TABLE 2 AVERAGE MONTHLY MW AVAILABILITY JAN. TO DEC. 2007                                                                 ...
The unit was restored on the 3rd week of September, 2006. By November, 2006 itdeveloped bearing vibration trouble. It was ...
2007 AVE. MONTHLY MW AVAILABILITY                                                                JANUARY-DECEMBER 2007 CHA...
Afam GT13 had been on outage due to turbine failure since February 1997. By the endof 2007, the unit was still unavailable...
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 81M...
Delta GT15 was available from January to March 2007. It developed starting problemand remained out of service by 31st Dece...
of June and went on planted outage in the last week of August. It was thereafter availabletill 31st December, 2007.Egbin S...
Barge 204 was on the grid between January and 5th April when it was shutdown due tocondensate problem. It was tied back on...
TABLE 3. SUMMARY OF GENERATION CAPABILITIES OF PHCN POWER      STATIONS AS OPERATED IN THE YEAR 2007( JANUARY - DECEMBER )...
POWER STATIONS AVERAGE MW AVAILABILITY                                                                           JANUARY-D...
GT11 was available throughout the year except a five week outage between the 2nd weekof May and 3rd week of June (20th) wh...
a week. On 14th August it could not run due to low gas pressure that spanned 10 days.The unit was however available from 2...
Commissioning of the units commenced in December, 2007.GT1’s commissioning commenced on 7th. It ran for the rest of Decemb...
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Grid
Upcoming SlideShare
Loading in...5
×

Grid

2,428

Published on

Published in: Technology
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
2,428
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Transcript of "Grid"

  1. 1. 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
  2. 2. 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
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. 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
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. 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
  17. 17. 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
  18. 18. 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
  19. 19. 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
  20. 20. 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
  21. 21. 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
  22. 22. 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
  23. 23. 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
  24. 24. 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
  25. 25. 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
  26. 26. 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
  27. 27. 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
  28. 28. 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
  29. 29. 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

×