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PJM ©2007www.pjm.com 1DMS 404176
1/30/07
DMS 404176
PJM Optimal Voltage Control (AVC) System
--- EPRI Workshop, May 19-20, 2011
Jianzhong Tong, Dave Souder, Chris PilongPJM Interconnection
PJM ©2007www.pjm.com 2DMS 404176
1/30/07
KEY STATISTICSPJM member companies 600+millions of people served 51peak load in megawatts 144,644MWs of generating capacity 164,895 km of transmission lines 90,734GWh of annual energy 729,000generation sources 1,287square km of territory 425,431area served 13 states + DCinternal/external tie lines 250
26% of generation inEastern Interconnection
23% of load inEastern Interconnection
19% of transmission assetsin Eastern Interconnection
19% of U.S. GDP produced in PJM
6,038substations
PJM’s role in the US and the Eastern Interconnection
PJM ©2007www.pjm.com 3DMS 404176
1/30/07 ©2006 PJM 3
Backbone Transmission System
PJM ©2007www.pjm.com 4DMS 404176
1/30/07 ©2006 PJM 4
PJM EMS Modeling
Voltage levels of modeling
• 765 kV• 500 kV• 345 kV• 230 kV• 138 kV• 115 kV• 69 kV & below -
depending on detail required
Voltage levels of modeling
• 765 kV• 500 kV• 345 kV• 230 kV• 138 kV• 115 kV• 69 kV & below -
depending on detail required
Network Model Summary
• Node: 75,154• Bus: 13,548• Unit: 2459• CB: 59693• XF: 5463• Line: 11,805• Shunt: 2540
Network Model Summary
• Node: 75,154• Bus: 13,548• Unit: 2459• CB: 59693• XF: 5463• Line: 11,805• Shunt: 2540
PJM ©2007www.pjm.com 5DMS 404176
1/30/07
Purpose --- Voltage /Reactive Power Control
1. To control the system voltage profile to meet the customer requirements --- (Voltage Quality)
2. To control the power flow in the system to an optimal level to reduce losses --- (Energy Efficiency)
3. To control the reserve of reactive power to ensure its sufficiency during normal and emergency conditions to prevent voltage collapse (instability) --- (System Security)
PJM ©2007www.pjm.com 6DMS 404176
1/30/07
Issues
Current approach of determination of the voltage schedule in PJM system:
1. Each TO determines their own area voltage schedule based on their Power Study and experiences. If TO has no voltage schedule for the area, PJM offer a default voltage schedule.
2. This approach is not optimal to determine PJM system voltage schedule.
3. Potentially, violation of voltage occurred frequently and unexpected massive flow of reactive power (leads to depress the level of security and economy)
PJM ©2007www.pjm.com 7DMS 404176
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Proposed Solution – Optimal Dynamic Voltage Control System
Optimal Dynamic Voltage Control System (AVC):
1. Determine voltage schedule and Var control system-wide
2. Combine optimization and traditional approach (rule based)
3. Achieve the objective of minimum of system loss, or maximum of MW transfer
4. Improve system voltage profile, real time security and reliability .
PJM ©2007www.pjm.com 8DMS 404176
1/30/07
Optimal Dynamic Voltage Control System ---Two Levels of Optimizations
1. TVC is the tertiary voltage control level, responsible for economy (reduction in system loss), and is a slow control. TVC is a optimal solution to set the voltage setting (Vp1 to Vpn) for the pilot (key) buses in the system.
2. SVC is the secondary voltage control level, responsible for quality and security, and is a fast control. SVC is a optimal solution to set voltage schedule (Vg) for each generator in the system.
PJM ©2007www.pjm.com 9DMS 404176
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Optimal VoltageSchedule
Calculations (AVC Software)
Real-time SnapshotImport
(From PJM EMS)
Optimal Solutions Export
Log Management
Data I/O Management
Process Management
PJM AVC System
AVC Validation Software
PI database
Operation Planning Engineer
PJM ©2007www.pjm.com 10DMS 404176
1/30/07
• AVC Outputs:– AVC Runs Every Hour Automatically– AVC Results in June – September
•• Comparison of AVC Solutions and SE SolutionsComparison of AVC Solutions and SE Solutions– SE called “Before”; AVC called “After”– Base (SE) Violations– SA Violations– TLC Violations
•• Two Control ModesTwo Control Modes– Ctrl I : Control only for peak hours (7:00 am – 12:00 pm)– Ctrl II : Control for all the hours
PJM ©2007www.pjm.com 11DMS 404176
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System Loss (MW)Ctrl I
Jun Jul Aug SepAverage
Loss Before AVC
2027.7 2208.5 2056.1 1857.0
Average Loss After
AVC2007.0 2188.0 2036.2 1840.0
Average Reduction 20.7 20.6 19.9 17.1
Average Reduce% 0.95% 0.86% 0.97% 0.84%
Ctrl II
Jun Jul Aug SepAverage
Loss Before AVC
2027.7 2208.5 2056.1 1857.0
Average Loss After
AVC2001.2 2182.6 2030.9 1835.5
Average Reduction 26.5 25.9 25.2 21.6
Average Reduce% 1.29% 1.14% 1.23% 1.12%
0.00%
0.50%
1.00%
1.50%
0
500
1000
1500
2000
2500
Jun Jul Aug Sep
Before AVC After AVC Reduce Ratio
0.00%
0.50%
1.00%
1.50%
0
500
1000
1500
2000
2500
Jun Jul Aug Sep
Before AVC After AVC Reduce Ratio
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Var Reserve (Mvar)Ctrl I Ctrl II
Jun Jul Aug SepAverage Reserve
Before AVC38288.3 41107.3 39957.6 36685.6
Average Reserve
After AVC38648.6 41402.9 40275.1 36921.0
Average Increase 360.3 295.6 317.5 235.4
Average Increase% 0.94% 0.72% 0.79% 0.65%
Jun Jul Aug Sep
Average Reserve
Before AVC38288.3 41107.3 39957.6 36685.6
Average Reserve
After AVC38740.4 41503.8 40386.5 36999.7
Average Increase 452.1 396.5 428.9 314.1
Average Increase% 1.18% 0.96% 1.07% 0.84%
0.00%
0.25%
0.50%
0.75%
1.00%
0.0
10000.0
20000.0
30000.0
40000.0
Jun Jul Aug Sep
Before AVC After AVC Increase Ratio
0.00%
0.25%
0.50%
0.75%
1.00%
1.25%
0.0
10000.0
20000.0
30000.0
40000.0
Jun Jul Aug Sep
Before AVC After AVC Increase Ratio
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Voltage Violation——BaseCtrl I
Jun Jul Aug SepAverage Violation
Numbers Before AVC
12.6 14.7 15.9 18.2
Average Violation
Numbers After AVC
9.7 11.6 13.0 13.9
Average Reduction 2.9 3.1 2.9 4.3
Ratio with Improvement 99.85% 100.00% 99.83% 100.00%
Ctrl II
Jun Jul Aug SepAverage Violation
Numbers Before AVC
12.6 14.7 15.9 18.2
Average Violation
Numbers After AVC
4.2 4.9 6.1 5.0
Average Reduction 8.4 9.8 9.8 13.2
Ratio with Improvement 99.71% 99.63% 98.66% 100.00%
95.00%
96.00%
97.00%
98.00%
99.00%
100.00%
0
5
10
15
20
Jun Jul Aug Sep
Before AVC After AVC Improve Ratio
95.00%
96.00%
97.00%
98.00%
99.00%
100.00%
0
5
10
15
20
Jun Jul Aug Sep
Before AVC After AVC Improve Ratio
PJM ©2007www.pjm.com 15DMS 404176
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Overview
15
• Average voltage before and after AVC
All(p.u.) 765kV 500kV 345kV 230kV
Ctrl I
Before AVC 1.0158 768.3 524.1 352.8 234.9
AfterAVC 1.0188 770.9 526.0 353.8 235.5
Ctrl II
Before AVC 1.0158 768.3 524.1 352.8 234.9
AfterAVC 1.0194 771.8 526.7 354.2 235.6
PJM ©2007www.pjm.com 16DMS 404176
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Overview --- Contingency
16
PJM ©2007www.pjm.com 17DMS 404176
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Voltage Violation——Contingency
Time “cont high volt viol num”
“cont low volt viol num”
“cont volt viol num”considering peak
and off-peak load *
Ctrl I
Jun 66.91% 92.71% 92.72%
Jul 74.25% 91.42% 91.43%
Aug 59.43% 94.99% 94.99%
Sep 55.90% 97.82% 97.82%
Ctrl II
Jun 63.76% 85.30% 89.52%
Jul 72.25% 86.22% 89.39%
Aug 55.43% 92.82% 90.98%
Sep 51.97% 96.94% 93.89%
• Ratio with improvement
* For peak load, check the low voltage violations; For off-peak load, check the high voltage violations. 17
PJM ©2007www.pjm.com 18DMS 404176
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Voltage Violation——Contingency
Time
Average “high voltage
violation number”
before AVC
Average “high voltage
violation number”
after AVC
Average “low voltage
violation number”
before AVC
Average “low voltage
violation number”
after AVC
Average “low voltage drop number”before AVC
Average “low voltage
drop number”after AVC
Ctrl I
Jun 781.0 730.0 29.5 18.8 11.0 10.3
Jul 890.4 817.3 15.7 12.3 13.4 11.9
Aug 1035.4 1003.4 30.2 21.3 31.9 29.2
Sep 1231.2 1174.3 70.3 45.2 70.0 65.1
Ctrl II
Jun 781.0 589.3 29.5 18.6 11.0 10.1
Jul 890.4 601.9 15.7 12.1 13.4 11.7
Aug 1035.4 773.7 30.2 20.1 31.9 28.6
Sep 1231.2 818.6 70.3 44.2 70.0 64.2
• The number of voltage limit violations reduced
18
PJM ©2007www.pjm.com 19DMS 404176
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PJM ©2007www.pjm.com 20DMS 404176
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Overview
20
• Average Margin (MW)
EAST CENTRAL WEST BED-BLA APSOUTH
Ctrl I
Before AVC 2937.3 2315.2 2853.3 3118.3 2566.9
After AVC 3038.1 2433.2 3040.7 3223.9 2749.3
Ctrl II
Before AVC 2937.3 2315.2 2853.3 3118.3 2566.9
After AVC 3053.2 2460.1 3101.0 3236.3 2791.2
PJM ©2007www.pjm.com 21DMS 404176
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Voltage Stability Margin
Time EAST CENTRAL WEST BED-BLA APSOUTH
Ctrl I
Jun 97.53% 99.61% 97.62% 93.21% 98.22%
Jul 96.46% 98.78% 97.42% 90.91% 94.59%
Aug 90.20% 98.07% 96.19% 95.19% 94.41%
Sep 92.68% 98.38% 97.83% 97.52% 93.60%
Ctrl II
Jun 89.92% 94.54% 95.24% 78.97% 94.49%
Jul 87.92% 93.06% 95.28% 74.59% 87.17%
Aug 81.76% 95.29% 94.93% 86.48% 86.59%
Sep 82.11% 91.35% 91.30% 85.15% 82.76%
• Ratio with Improvement
21
PJM ©2007www.pjm.com 22DMS 404176
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Voltage Stability Margin• Average Margin (in MW, before/after)
22
Time EAST CENTRAL WEST BED-BLA APSOUTH
Ctrl I
Jun 3119.3/3221.4 2374.6/2485.4 2862.5/3025.7 3138.8/3217.1 2466.8/2673.7
Jul 2878.8/2966.7 2125.6/2240.1 2599.6/2776.6 3083.0/3195.8 2609.8/2794.6
Aug 2946.6/3053.2 2584.1/2706.2 3104.0/3320.1 3134.0/3244.3 2657.8/2808.3
Sep 2364.4/2496.1 1974.1/2111.1 2826.6/3032.5 3099.6/3257.3 2525.5/2711.8
Ctrl II
Jun 3119.3/3232.5 2374.6/2510.7 2862.5/3080.1 3138.8/3217.1 2466.8/2729.4
Jul 2878.8/2974.7 2125.6/2267.4 2599.6/2836.8 3083.0/3205.7 2609.8/2831.2
Aug 2946.6/3088.2 2584.1/2734.3 3104.0/3391.4 3134.0/3272.0 2657.8/2850.5
Sep 2364.4/2509.0 1974.1/2137.8 2826.6/3080.7 3099.6/3271.2 2525.5/2723.5
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Significant potential benefits can be achieved with AVC techniques in both aspects of security and economy:
1.average reduction of transmission system loss is about 1.19%, which means energy savings of more than 220 million kWh/year and monetary savings of more than $17 million/year; 2.Average increase of system VAR reserve is about 1.08%; 3.Improvement on system security for pre-contingency and post-contingency is significant, including improvement on these security indices in voltage limits violations, and voltagestability limits violations.
Conclusions
PJM ©2007www.pjm.com 24DMS 404176
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Appendix A
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Example of Voltage Stability Margin Analysis
• APSOUTH Interface – Bus Voltage
Greenland Gap 500kV
517
518
519
520
Jun Jul Aug Sep
Mt. Storm4 500kV
516
518
520
522
Jun Jul Aug Sep
Doubs 500kV
524
526
528
Jun Jul Aug Sep
Meadow Brook 500kV
520
522
524
526
Jun Jul Aug Sep
522
524
526
528
Jun Jul Aug Sep
Valley4 500kV
Average Voltage
PJM ©2007www.pjm.com 26DMS 404176
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Voltage Stability Margin Analysis• APSOUTHh Interface -- Generators
0
5
10
Jun Jul Aug Sep
36.5
37
37.5
Jun Jul Aug Sep
Greenland Gap 35kV G1
21.2
21.4
21.6
Jun Jul Aug Sep
150
200
250
Jun Jul Aug Sep
Mt. Storm4 22kV G1
21
21.5
22
Jun Jul Aug Sep
0
150
300
Jun Jul Aug Sep
Mt. Storm4 22kV G2
23.2
23.4
23.6
Jun Jul Aug Sep
0
100
200
Jun Jul Aug Sep
Mt. Storm4 22kV G3
Average Voltage
Average Var Reserve
PJM ©2007www.pjm.com 27DMS 404176
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Voltage Stability Margin Analysis• APSOUTH Interface – Area & Zone
Area 13, APSZone 16, APSS
Area 17, DOMZone 46, DOM-W
Average Voltage
Average Var Reserve
Area 13, APS
0
1500
3000
Jun Jul Aug Sep
1.03
1.04
1.05
1.06
Jun Jul Aug Sep
0
3000
6000
Jun Jul Aug Sep
Area 17, DOM
1.03
1.04
1.05
1.06
Jun Jul Aug Sep
0
1500
3000
Jun Jul Aug Sep
Zone 16, APSS
1.03
1.04
1.05
1.06
Jun Jul Aug Sep
0
800
1600
Jun Jul Aug Sep
Zone 46, DOM-W
1.03
1.04
1.05
Jun Jul Aug Sep
PJM ©2007www.pjm.com 28DMS 404176
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• Why there is a larger margin increase in September?The higher voltage levelThe bus voltages related to APSOUTH interface become much higher after AVC, especially for receiving side buses.
The more reasonable distribution of reactive powerThe Var reserve in Area13/Zone16 becomes less after AVC, and the voltage becomes higher, that means this area can meet the reactive power needs by itself, and the transmission of reactive power between different areas is reduced.
28
Voltage Stability Margin Analysis - APSOUTH Interface
PJM ©2007www.pjm.com 29DMS 404176
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• Why there is a larger margin increase in September?The more flat voltage distributionThe mean square deviation of voltage in September is much smaller after AVC, that means the bus voltages distribution is more flat.
29
Voltage Stability Margin Analysis - APSOUTH Interface
0.024
0.025
0.026
0.027
Jun Jul Aug Sep
Mean square deviation of voltage
PJM ©2007www.pjm.com 30DMS 404176
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Appendix B
PJM ©2007www.pjm.com 31DMS 404176
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Voltage Curve on Critical Bus
31
• CHICKHOM-500kV
500
510
520
530
540
500
510
520
530
540
500
510
520
530
540
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Voltage Curve on Critical Bus
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• KAMMER2 -500kV
500
510
520
530
540
550
500
510
520
530
540
550
500
510
520
530
540
550
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Voltage Curve on Critical Bus
33
• KAMMER2 -765kV
720
730
740
750
760
770
720
730
740
750
760
770
720
730
740
750
760
770
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Voltage Curve on Critical Bus
34
• ORCHARD -500kV
500
510
520
530
540
550
510
520
530
540
550
510
520
530
540
550
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Voltage Curve on Critical Bus
35
• PRUNTYTO-500kV
500
510
520
530
540
500
510
520
530
540
500
510
520
530
540
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Voltage Curve on Critical Bus
36
• MTSTORM2 500KV
500
510
520
530
540
500
510
520
530
540
500
510
520
530
540
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Voltage Curve on Critical Bus
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• MTSTORM4 500KV
500
510
520
530
540
500
510
520
530
540
500
510
520
530
540
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Voltage Curve on Critical Bus
38
• JUNUATA 500KV
500
510
520
530
540
550
500
510
520
530
540
550
500
510
520
530
540
550
PJM ©2007www.pjm.com 39DMS 404176
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Voltage Curve on Critical Bus
39
• CONEMAUG 500KV
500
510
520
530
540
500
510
520
530
540
500
510
520
530
540
PJM ©2007www.pjm.com 40DMS 404176
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Voltage Curve on Critical Bus
40
• LIMERICK 500KV
500
510
520
530
540
550
500
510
520
530
540
550
500
510
520
530
540
550
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Voltage Curve on Critical Bus
41
• PEACHBOT 500KV
500
510
520
530
540
550
500
510
520
530
540
550
500
510
520
530
540
550
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Voltage Stability Margin
• The percentage of margin increase/decrease hours
Ctrl I
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Voltage Stability Margin
• The percentage of margin increase/decrease hours
Ctrl II
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margin decrease hours IS MINIMUM
• Take “Ctrl II” as example.
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For these margin decrease, margin after AVC still enough
• Take “Ctrl II” as example.
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Voltage Stability Margins are Good in Worst Decrease
Time EAST CENTRAL WEST BED-BLA APSOUTH
Ctrl I
Jun 3996/3410 1465/1441 1981/1488 4465/3785 2824/2238
Jul 4160/3574 4348/4184 5285/4488 3598/2988 2941/2473
Aug 3152/2895 2941/2801 3316/2988 6316/5543 5238/4441
Sep 3762/3481 4231/3996 6035/5848 5871/5754 5520/5027
Ctrl II
Jun 3996/3410 5121/5027 1981/1488 3691/2918 3598/2988
Jul 3246/2637 5027/4816 5285/4488 3598/2988 2941/2473
Aug 3996/3668 3106/2965 5895/5566 6316/5543 5238/4441
Sep 3762/3481 4231/3996 5777/5566 4606/4418 5074/4512
• For Example: Worst Margin Decrease (in MW before/after)
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Voltage Stability Margins are Good in Worst Decrease
Time EAST CENTRAL WEST BED-BLA APSOUTH
Ctrl I
Jun 926/ 879 1395/1371 1887/1488 2074/2027 1746/1723
Jul 2426/2238 1535/1488 1418/1254 1723/1652 1934/1887
Aug 1254/1184 973/ 949 1137/ 949 1981/1746 1746/1676
Sep 973/ 926 3691/3574 2051/2004 2895/2801 2262/2074
Ctrl II
Jun 926/ 879 1395/1371 1887/1488 1981/1957 1746/1723
Jul 2238/2215 1535/1488 1418/1254 1441/1418 1934/1887
Aug 1254/1184 973/ 949 973/ 832 1981/1746 1746/1676
Sep 973/ 926 2848/2824 2051/2004 2637/2566 2262/2074
• For Example: Minimum Margin in Margin Decrease Hours(in MW before/after)