pjm optimal voltage control (avc) system --- epri workshop...

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


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


1/30/07 ©2006 PJM 3

Backbone Transmission System


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


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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)


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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)


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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 .


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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.


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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


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• 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


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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 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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12

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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13


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14

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


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


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


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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


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Overview --- Contingency

16


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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


1/30/07

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


violation number”

after AVC

Average “low voltage drop number”before AVC


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


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19


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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


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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


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Voltage Stability Margin• Average Margin (in MW, before/after)

22


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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23

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


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24

Appendix A


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25

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


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26

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


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27

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


1/30/07

• 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


1/30/07

• 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


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30

Appendix B


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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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32

• KAMMER2 -500kV

500

510

520

530

540

550

500

510

520

530

540

550

500

510

520

530

540

550


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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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34

• ORCHARD -500kV

500

510

520

530

540

550

510

520

530

540

550

510

520

530

540

550


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35

• PRUNTYTO-500kV

500

510

520

530

540

500

510

520

530

540

500

510

520

530

540


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36

• MTSTORM2 500KV

500

510

520

530

540

500

510

520

530

540

500

510

520

530

540


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37

• MTSTORM4 500KV

500

510

520

530

540

500

510

520

530

540

500

510

520

530

540


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38

• JUNUATA 500KV

500

510

520

530

540

550

500

510

520

530

540

550

500

510

520

530

540

550


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39

• CONEMAUG 500KV

500

510

520

530

540

500

510

520

530

540

500

510

520

530

540


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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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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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42


• The percentage of margin increase/decrease hours

Ctrl I


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43


• The percentage of margin increase/decrease hours

Ctrl II


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44

margin decrease hours IS MINIMUM

• Take “Ctrl II” as example.


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45

For these margin decrease, margin after AVC still enough

• Take “Ctrl II” as example.


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46

Voltage Stability Margins are Good in Worst Decrease


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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47

Voltage Stability Margins are Good in Worst Decrease


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)

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