Power Management

1. High Voltage (69 kV) Network Operational Review
(Demerara & Berbice Interconnected Transmission Network)

2. Introduction
Aim
To improvethe resilience of the transmissionnetwork (69 KV) of DBIS;
Objectives
 Network voltage level stability issue – Reasons / control features;
 Operationof generatingstations – Normal & Power failure restorationPeriod;
 Level of reactive power (MVAR) and regulationwith reference;
StudyPeriod: August - September 2021
GPLlookingforwardshort term measureson priority;
Longterm programinpipeline, mainly installationof CapacitorBanks,new SCADA station;
Highercapacitygeneratorsintegrationto meet growingelectricity demand;

3. Transmission Network (69 KV)
Based on the collected information, Load flow in the HT network is ~65 MW

4. Data
Result
Information
Analyze
Action
Measure
you can’t manage what you don’t measure
Importance of Records

5. Demerara : Power Generation
Location Generation Unit Installed Capacity,
MW
Operating load,
MW
Mode of
Operation
Actual
Operation
Remark
Garden of Eden
DP # 1
#5 DA 3.0
#6 DA 4.0 3.9 0.9 pf lag
#1 DG 5.5 5.4 SD-VD SD - PF 0.93 pf lag (14.0 KV)
#2 DG 5.5 5.1 SD-VD SD - PF 0.91 pf lag (14.0 KV)
#3 DG 5.5 3.8 SD-PF KW-PF 0.83 pf lag (14.2 KV)
#4 DG 5.5 5.0 KW-PF KW-PF 0.88 pf lag (14.2 KV)
Kingston (DP # 2) #1 DG 5.5 5.3 KW-PF KW-PF 0.94 pf lag
#2 DG 5.5 5.2 SD-PF KW-PF 0.94 pf lag
#3 DG 5.5 5.3 SD-PF KW-PF 0.94 pf lag
#4 DG 5.5 5.2 KW-PF KW-PF 0.94 pf lag
Kingston (DP # 3) #1 DG 6.9 6.0 SD-PF SD-PF 0.83 pf
#2 DG 6.9 4.0 KW-PF kW - PF
#3 DG 6.9 6.85 SD-PF kW - PF 0.84 pf
#4 DG 7.8 7.6 SD-PF SD-PF 0.84 pf
#5 DG 7.8 7.6 SD-PF SD-PF 0.84 pf
Vreed-En-Hoop
(DP # 4)
#2 DG 8.7 5.7 ICM - Voltage ICM - Voltage 0.90 pf
#3 DG 8.7 5.8 ICM - Voltage ICM - Voltage 0.88 pf
Sophia 3 X CAT 2 X 1.6 3.0
Giftland DG I X 2.0
Total 108.6 90.75±2
Variation in Power factor at 13.8 KV bus w.r.t generators’ operation

6. Berbice : Power Generation
Location Generation Unit Installed Capacity Operating load, MW Remark
MW MW
Cane field #3 DA 4.0 4.0
#8 CAT 1.5 1.5
#9 CAT 1.0
#11 CAT 1.6 1.6
2 X 1.6
Onverwagt #1 CAT 1.6 2.3
#2 CAT 1.6 1.4
#12 CAT 0.8
#14 CAT 0.8
#17 CAT 1.6 1.4
Skeldon /
PPDI 5 #2 DG 2.5 2.5
#3 DG 2.5 2.5
Total 18.7 17.2
Most of the generators operate to full capacity; Total generation : 110 ± 2 MW
The mode of operation of a few generators were different from the actual defined operating procedures
- It is suggested to report variation in the mode of operation in the daily report (PPDI to GPL)
Reasons for lower power factor at DP # 3 can be reviewed

7. Transmission Network – Transformers
Substation Make Rating of
Transformer, MVA
Voltage, KV Impendence, % Status
Demerara Region
Garden of Eden (G) ABB 16.8 69 / 13.8 8.10 Damaged
Westinghouse 16.8 69 / 13.8 11.59
Westinghouse 16.8 69 / 13.8 11.59
Golden Grove Dachi 10.0 69 / 13.8 11.42
Dachi 10.0 69 / 13.8 11.18
Sophia Old ABB 16.8 69 / 13.8 8.10 Damaged
Westinghouse 16.8 69 / 13.8 11.59 OFF
ABB 16.8 69 / 13.8 8.10
New Georgetown Dachi 16.7 69 / 13.8 11.19
Dachi 16.7 69 / 13.8 11.10
Kingston (G) Sunbelt 35.0 69 / 13.8 10.66
Crompton Greeves 35.0 69 / 13.8 10.90
Vreed-en-Hoop Dachi 2 X 20.0 69 / 13.8 11.29 OFF (TR#1)
Edinburgh Dachi 10.0 69 / 13.8 11.27
Good Hope Crompton greaves 35.0 69 / 13.8 10.90
Columbia Dachi 16.7 69 / 13.8 11.12
Onverwagt Dachi 16.7 69 / 13.8 11.04
Barbice Region
Canefield (G) Dachi 16.7 69 / 13.8 11.09
No 53 Village Federal pioneer 16.7 69 / 13.8 10.90
Skeldon Dachi 16.7 69 / 13.8 11.09
Few transformers are with off load tap changers; Old transformers are being operated in fixed transformation ratio

8. 69 kV Transmission lines data analysis
− Coming 'IN' or Import + going 'OUT' or Export
TL name
Point 1 Point 2 Voltage difference Current difference
MW PF %Uunb %Iunb MW PF %Uunb %Iunb Uab Ubc Uca IA IB IC
TL-1: GOE - Golden Grove -7.78 -0.96
TL-2: Sophia - Golden Grove -3.04 -0.88 1.9 8.6 4.04 0.99 1.7 11.2 -533 -833 -740 7.1 2.3 7.7
TL-3: GOE - Golden Grove 8.03 -0.96
TL-4: New Sophia - Golden
Grove -2.94 -0.87 1.9 8.8 3.99 0.99 1.7 10.3 -624 -922 -830 7.4 2.1 6.9
TL-5: Kingston - Sophia 29.28 0.92 1.9 7.4 -27.56 -0.93 1.9 7.3 -3465 -3486 -3605 -3.4 -3.0 -3.6
TL-6: Kingston - Vreed-en-
hoop -4.92 -0.96 1.8 35.8 4.99 0.94 1.9 33.2 -100 -16 67 1.7 0.5 0.3
TL-7: Vreed-en-hoop -
Edinburgh 7.73 0.88 1.9 12.1 -7.69 -0.87 2.2 12.5 -823 -489 -520 1.1 1.5 0.6
TL-10: Sophia - New
Georgetown 12.4 0.94 2.0 7.1
TL-12: Sophia - New Sophia 3.82 0.73 1.9 19.3 -3.80 -0.73 2.0 19.7 15 42 111 -0.1 -0.1 -0.3
TL-13: Sophia - New Sophia 4.81 0.97 2.0 11.8 -5.14 -0.97 2.0 12.0 2664 2796 2713 1.5 1.3 1.1
TL-16: New Sophia - Good
Hope 11.8 0.87 2.0 15.0 -11.71 -0.87 2.3 15.0 -968 -649 -594 0.4 0.5 0.4
TL-17: Good Hope - Columbia 1.17 0.92 2.4 35.5 -1.35 -0.90 2.2 29.8 -238 -499 -313 3.2 3.3 3.8
TL-20: Columbia - Onverwagt -2.51 -0.97 2.2 35.7 2.59 1.00 1.8 39.4 521 12 247 0.2 -0.4 2.3
TL-21: Onverwagt - Canefield -1.94

9. 69 kV Transmission lines data analysis
 Voltages at the transmission line ends are found to be below 65 kV, i.e. as low as 63 kV;
- Less than the standard value mentioned in the GPL electricity grid code;
 Voltage drop in TL # 5, 13 are very high even though the line length is small;
 Unbalance voltage for all the 69 kV transmission lines varies from 1.7% to 2.3%;
 In some of the feeders (namely TL # 6, 12, 13, 17 & 20), unbalanced currents are found
varying dynamically from 10% to 80%;
 All the transmission lines are loaded in the range of 1% to 40%;
- TL # 5 is loaded around 40%, and all other lines are loaded less than 25%.
 International standards (e.g., EN-50160 and the IEC 1000-3-x series) give limits for the
unbalance ratio of < 2% for low voltage and medium voltage systems, and <1% for high
voltage, measured as 10 min intervals, with an instantaneous maximum of 4%.
 Current unbalance should be < 5% for high voltage networks.

10. Malfunctioning of SCADA
SCADA measurements at Golden Grove end of 69 kV transmission lines, TL # 2 & 4 are not
working. The same value is being shown for 24 hours for many days.
Date
Average kW/hour
Line # 1 Line # 2 Line # 3 Line # 4
Sending end
Receiving
end
Sending end Receiving end Sending end Receiving end Sending end Receiving end
01-09-2021 No data 7.79 2.81 4.04 No data 8.03 4.54 3.99
02-09-2021 No data 7.79 4.64 4.04 No data 8.03 3.68 3.99
03-09-2021 No data 7.79 2.82 4.04 No data 8.03 2.79 3.99
04-09-2021 No data 7.79 1.73 4.04 No data 8.03 4.11 3.99
05-09-2021 No data 7.79 2.53 4.04 No data 8.03 2.51 3.99
06-09-2021 No data 7.79 3.61 4.04 No data 8.03 3.63 3.99
07-09-2021 No data 7.79 4.66 4.04 No data 8.03 2.92 3.99
08-09-2021 No data 7.79 3.76 4.04 No data 8.03 3.73 3.99
09-09-2021 No data 7.79 3.21 4.04 No data 8.03 5.12 3.99
10-09-2021 No data 7.79 3.21 4.04 No data 8.03 3.13 3.99
11-09-2021 No data 7.79 3.4 4.04 No data 8.03 2.56 3.99
12-09-2021 No data 7.79 4.1 4.04 No data 8.03 3.88 3.99
13-09-2021 No data 7.79 2.83 4.04 No data 8.03 2.85 3.99
14-09-2021 No data 7.79 3.67 4.04 No data 8.03 2.96 3.99
15-09-2021 No data 7.79 2.93 4.04 No data 8.03 4.86 3.99
16-09-2021 No data 7.79 2.99 4.04 No data 8.03 4.64 3.99
17-09-2021 No data 7.79 5.73 4.04 No data 8.03 1.92 3.99
18-09-2021 No data 7.79 1.14 4.04 No data 8.03 1.34 3.99
19-09-2021 No data 7.79 2.31 4.04 No data 8.03 2.35 3.99

11. Substation : Kingston
 Installed transformers 2 X 35 MVA;
 DP 2 and DP 3 interconnected;
 Total power generation : 53 MW (21 + 32)
 DP 3 : Generators 1/2/3 connected feeder B1F1 connected to Step-up transformer 13.8 / 69 KV;
: Generators 4/5 connected with submarine cable 69 KV
 Load flow through transformers 36 – 42 MW;
Position G 1/2/3 G 4 /5
Generation end
voltage
14.07 / 14.32 /
13.95
14.03 / 14.28 /
13.91
HT Voltage
levels
66.5/68.7/67.9 66.5/68.7/67.9
Line # 2
(66.2 kV, 68.4
kV, 67.6 kV)
Line # 5
(63.5 kV, 65.7
kV, 64.8 kV)

12. Verified Energy Losses between Kingston to Sophia – Line 5
Total daily energy transmitted by L5 line : 705 MWh
Energy lost during transmission : 37.8 MWh (> 2.0 MW during peak hour)
Percentage of Energy loss : 5.4%
Substation : Kingston

13. Monitored Voltage drop – Line 5
Present load of 40+MW (maximum) observed voltage drop 3.5 – 4.0 KV
Substation : Kingston
Kingston Sophia
UAB UBC UCA P Q PF UAB UBC UCA
66.52256 68.78325 67.86572 30.80922 12.90084 0.922546 62.95576 65.32427 64.23491
66.22832 68.63052 67.5917 30.10413 11.78894 0.930573 62.77495 65.1895 64.10239
66.36308 68.69453 67.6602 28.46538 11.87914 0.922913 62.92319 65.26025 64.19448
66.43159 68.70801 67.72422 27.67547 11.89675 0.918854 62.92319 65.331 64.18213
66.49111 68.67207 67.77476 26.65628 12.00061 0.911896 62.97148 65.32202 64.25063
66.02729 68.41826 67.37046 26.23294 10.75232 0.925385 62.63906 64.99072 63.94292
66.18789 68.51372 67.52094 25.60259 11.54384 0.911621 62.79853 65.16929 64.08218
66.38105 68.59121 67.60517 23.82441 12.34848 0.887909 63.01978 65.20522 64.13721
65.86558 67.97129 67.1144 27.31178 13.26597 0.899643 62.32124 64.56059 63.56221
65.87006 68.03193 67.18291 32.14322 15.98931 0.895905 62.1685 64.43481 63.49146
66.2418 68.28574 67.54116 30.5016 16.24339 0.88295 62.55371 64.72681 63.82612
66.55737 68.58447 67.86797 25.49766 15.47217 0.855759 63.01753 65.0918 64.17539
66.51582 68.52607 67.78823 25.23603 15.6993 0.849182 62.91421 65.00981 64.18662
66.18565 68.31494 67.56138 26.70803 14.34589 0.881363 62.62671 64.82002 63.87441
66.0666 68.21723 67.44346 27.07172 14.26611 0.884689 62.59751 64.74253 63.94067
66.14409 68.28574 67.51421 26.93372 14.69808 0.876968 62.59526 64.78408 63.91035
66.7831 69.00449 67.93198 31.88519 16.2053 0.891541 63.00405 65.26475 64.29443
67.18516 69.24707 68.37783 31.73425 16.0292 0.892578 63.51953 65.69599 64.7414
66.84263 68.94048 68.10156 24.83784 15.99902 0.840988 63.28818 65.43095 64.44267
67.05264 69.43462 68.45083 35.52063 15.80064 0.913742 63.27246 65.63422 64.59766
66.6708 69.03931 68.12627 34.74725 14.47239 0.922485 62.97373 65.46802 64.36518
66.62588 68.98428 68.05776 33.42259 13.5337 0.92691 62.98047 65.46352 64.34272
66.62812 68.87983 67.99375 32.40197 12.96841 0.928894 63.01978 65.45117 64.33823
66.66631 68.90904 67.98701 28.56025 12.65755 0.914398 63.21743 65.48149 64.46963
Single phase voltage : 62.9 kV
% deviation to 69 KV : 8.8%
As per GPL grid code, the maximum voltage
regulation allowed : ± 5% (65. 5 KV)
Installation of capacitor bank to improve
voltage important.
(15 MVAr at New Sophia)

14. Substation : Vreed-En-Hoop
Currently, a project was initiated to shift 20 MVA transformer from Vreed-en-hoop to Edinburgh (to
replace with the existing 10 MVA transformer)
 Installed transformers 2 X 20 MVA; Operational 1 X 20 MVA;
 Total Generation at Vreed-En-Hoop : 11.5 – 13.5 kW (each 5.7 – 6.7 MW)
 F1 directly to transmission Edinburgh : 6.4 – 8.7 MW (at pf 0.88)
West Bank Distribution feeders 13.8 KV bus : 5.0 MW
Position G 2 G 3
Generation end voltage 14.0 / 14.2 / 13.9 13.9 / 14.2 / 13.9
HT Voltage levels (Line # 7) 66.7 / 68.89 /68.24
HT voltage at Edinburgh 65.9 / 68.49 / 67.7
Step down transformer at Edinburgh : 1 X 10 MVA
Mid Night load (19.00 – 24.00 PM) : 8.7 MW at 0.87 : 10 MVA Fully loaded
(around 108% during peak hours)

15. Transformer loading : (9.5 MW / 0.87 pf : 10.9 MVA); Transformer rating : 10 MVA
Loading on transformer > 100% during evening hours
Substation : Edinburgh
Edinburgh
IA IB IC UAB UBC UCA P Q PF
102.3706 75.40649 76.36719 66.54277 69.33804 68.3419 -8.62931 -4.66289 -0.87944
98.62549 72.31323 73.55225 66.00596 68.78999 67.81069 -8.23993 -4.43469 -0.88144
96.33301 70.68604 72.10815 65.62974 68.34638 67.38506 -8.03167 -4.28797 -0.88249
93.88428 69.02832 69.99023 65.90488 68.54404 67.6063 -7.82773 -4.21583 -0.87988
91.37695 66.88599 68.22876 65.53652 68.19814 67.32329 -7.56502 -4.10577 -0.87993
90.24902 66.49658 67.54639 65.94643 68.57212 67.58271 -7.49423 -4.15258 -0.87575
83.79395 62.23633 62.65991 66.40688 69.04043 68.02519 -6.93702 -4.04414 -0.86363
80.34424 59.87183 60.01831 66.26762 68.79224 67.79497 -6.56884 -3.98646 -0.85588
84.55566 64.021 65.00855 66.29907 68.76079 67.91289 -6.99272 -4.324 -0.85089
87.99805 68.02002 68.54614 66.554 69.03593 68.2689 -7.36881 -4.62624 -0.84705
90.29785 68.63892 70.45044 66.58433 69.04717 68.30483 -7.55065 -4.68544 -0.84955
93.98682 71.38428 72.86133 66.554 69.09321 68.2644 -7.83779 -4.85641 -0.85103
94.89746 70.80566 72.10815 66.54502 69.20439 68.40591 -7.83905 -4.79631 -0.85335
94.31885 69.3457 71.6394 66.47651 69.13813 68.22734 -7.76591 -4.69506 -0.85571
94.95361 72.28149 74.17847 66.50459 69.09321 68.18242 -7.95477 -4.90304 -0.85101
97.99316 74.08203 75.55908 66.3541 69.03819 68.13638 -8.1199 -5.0379 -0.84963
96.88232 72.38403 74.38477 66.58881 69.23135 68.30259 -8.04263 -4.90322 -0.85422
94.80225 72.04346 72.73438 67.00098 69.51772 68.59458 -7.89799 -4.95794 -0.84799
104.5508 78.05664 79.82666 66.47202 69.14936 68.1959 -8.71736 -5.15676 -0.86076
113.1348 82.19727 84.66553 66.19238 69.05615 68.11391 -9.43503 -5.14769 -0.87744
113.5718 83.14209 85.79834 66.20586 69.05615 68.08921 -9.57537 -5.11867 -0.88188
113.2861 82.39746 85.23682 66.13062 69.03593 68.03642 -9.52434 -5.04473 -0.88458
108.7085 80.17578 81.72852 66.09917 68.90342 68.03193 -9.19407 -4.85156 -0.88438
102.1411 75.08179 76.58203 66.54726 69.33354 68.3374 -8.62374 -4.65094 -0.88008
Augmentation of
transformer to 20MVA will
not improve voltage
Installation of capacitor
bank to improve voltage is
important.
(10 MVAr at Edinburgh)

16. 13.8 kV distribution feeder data analysis
Description
Feeder-1 Feeder-2 Feeder-3 Feeder-4
%Vunb %Iunb MW %Vunb %Iunb MW %Vunb %Iunb MW %Vunb %Iunb MW
Vreed-en-hoop 1.0 10.9 3.3
Edinburgh 2.4 21.9 2.6 2.5 25.0 4.5 2.4 20.1 1.5
Good Hope 2.3 28.2 1.9 2.1 20.9 3.3 2.3 31.5 2.3 2.2 31.4 4.5
Columbia 1.9 14.5 1.8 1.7 9.3 2.2
Onverwagt 1.4 9.6 0.6 1.3 13.9 -1.2
Canefield-Corentyne
No.53 Village-Corentyne
Skeldon
Garden of Eden
Golden Grove 1.7 6.2 4.1 1.8 18.8 4.0
Kingston
Sophia upgraded
New Georgetown
• Total no. of 13.8 kV feeders = ~50
• No. of feeders where data is available : 14
• Edinburgh and Good Hope feeders have large voltage and current unbalances.
• 13.8 kV distribution feeder level voltage at 'Sophia upgraded' substation is on the lower side, i.e., 13.4 kV.
Unbalance currents in the distribution feeders are the leading cause of increased voltage unbalance at the 13.8 kV level. It is also
affecting the voltage at generating units resulting in unbalanced power.

17. End user PQ analysis – Golden Grove to Diamond

18. End user PQ analysis – GWI Pouderoyen
Use of single phase transformer phase
wise are in place for voltage balance at
end user.
Different size of single phase transformers
are installed ( 2 X 50 KVA + 1 X 75 KVA)

19. Capacitor installation at Canefield substation
Shunt Capacitor
Installation Status
Transformer Tap Position
Onverwagt S/S Canefield S/S Village 53 S/S
Number of Taps 5 13 33
Before 5 13 30/33
After 3 5 20
Capcitor
bank
Status
Date:
23/09/20
21 Time:
69 kV line voltage
OFF 7:00 66.5 68.1 67.7 66.6 68.1 67.7
ON 19:00 70.1 71.5 71.3 70.1 71.5 71.4
L21
Onverwagt Canefield L22
Canefield Village 53

20. Distribution Feeders : Load balance
 Some of the 13.8 kV distribution
feeders which are having high
unbalanced currents is shown in
above table along with number of
customers connected to the line and
the load it is carrying.
 It is suggested to select two/three
distribution feeders and conduct a
survey to identify the type and
quantity of consumers
 like a number of households,
 hospitals,
 schools,
 street lights,
 commercial buildings,
government offices etc.
Location Feeder Connected areas
Load,
MW
% unbalance
Number of
customers
Voltage Current
Edinburgh
substation
F1 Windsor Forest, Best
Village GAB
2.50 2.4 21.9 3496
F2 Parika, Zeelugt,
Philedelhia, Le Destin,
Lookout
4.10 2.5 25.0 11849
F3 1.41 2.4 20.1
Good
Hope
substation
F1 Success, Lusignan 1.90 2.3 28.2 7736
F2 3.30 2.1 20.9
F3 Enmore factory road,
Hope SAB
2.90 2.3 31.5 9819
F4 4.00 2.2 31.4
Golden
Grove
F3 Diamond 4.04 1.8 18.8 7609
 Set a target to bring down the unbalance current below 15%
 By physically balancing the loads among the three phases
equally.
 Identifying loads that are contributing major unbalances in
the network
 If required bifurcate residential and industrial loads by
drawing a separate transmission line.

21. Suggested Measures on Priority
 L5: Sophia-Kingston 69kV line: High voltage drop observed which is around 3.5 kV
and power loss of around 2 MW;
 High Voltage drop in L13: Sophia-New Sophia line (2.5 KV);
 High unbalance currents observed in 69kV network – L6, L17, L20
- Total load on this lines = 8.5 MW
 Improving the SCADA is very essential;
- Report - transmission limits and limits violations; energy losses.
 New Industrial parks to be connected with separate feeders (without domestic loads)
 Distribution feeders (13.8 KV) load balance activities to be taken-up with set target (say
unbalance currents to minimise < 15%),
TERI team committed to work with GPL - distribution team to minimise power quality issues.
Installation of capacitor bank to improve voltage important
Edinburgh substation : 10 MVAr
New Sophia substation : 15 MVAr