Post on 24-Jan-2021
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WWSIS‐3: Western Interconnection Frequency Response and Transient Stability Study
Kara Clark, NREL
Nick Miller, Miaolei Shao, Slobodan Pajic, Rob D’Aquila, GE
12/17/15
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Western Wind & Solar Integration Study ‐ Phase 1
wind
coal
nuclear
hydroCombined cycle
Gas turbinePVCSP
WWSIS 1: The worst week of three years
Can we integrate high penetrations of wind and solar (i.e. 35%) into the Western Interconnection?
Yes, but….operational changes needed, such as increased balancing area cooperation, sub‐hourly scheduling, access to under used transmission, use of wind and solar forecasts, etc
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From a system perspective, cycling costs and emissions impacts of cycling are relatively small
Western Wind & Solar Integration Study ‐ Phase 2
What is the impact of 33% wind and solar on the fossil fuel plant cycling and emissions?
Western Wind and Solar Integration Study Phase 3 –Frequency Response and Transient Stability
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How do high penetrations of inverter‐based generation resources like wind and PV solar affect system reliability in the first minute after a large disturbance?
• Examine Western Interconnection large scale stability and frequency response with high wind and solar penetration
• Explore how power system reliability can be maintained by mitigating any adverse impact via advanced controls, transmission, storage, etc
WWSIS 3
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WECC-Wide Summary(1) Light Spring Base(2)
Light Spring High Mix
Light Spring Extreme Sensitivity
Wind (GW) 20.9 27.2 32.6
Utility-Scale PV (GW) 3.9 10.2 13.5
CSP (GW) 0.9 8.4 8.3
Distributed PV (GW) 0 7.0 10.4
Total (GW) = 25.7 52.8 64.8
Penetration(3) (%) = 21% 44% 53%
WWSIS 3 ‐ Light Spring Load Study ScenariosBase Case High Mix Case
(1) Western Electricity Coordinating Council includes parts of Canada and Mexico, (2) Provided by WECC, (3) Penetration is % of total generation for this snapshot.
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59.4
59.5
59.6
59.7
59.8
59.9
60
60.1
0 10 20 30 40 50 60
Freq
uency (Hz)
Time (Seconds)
FrequencyMinimum or Nadir
Settling Frequency
First threshold for UFLS
NERC Frequency Stability CriteriaNERC BAL‐003‐1* sets:Design‐basis outage(2 Palo Verde units =~2750MW)Frequency response(FR) metricInterconnection frequency response obligation (IFRO, 840 MW/0.1Hz)
Goals are:Meet IFRO (840 MW/0.1Hz)Avoid under‐frequency load shedding (UFLS)
*http://www.nerc.com/pa/Stand/Project%20200712%20Frequency%20Response%20DL/BAL‐003‐1_clean_031213.pdf
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WWSIS Phase 3 Frequency Response
Disturbance: Trip 2 Palo Verde units (~2,750MW)
3
2
Light Spring BaseLight Spring High MixLight Spring Extreme
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1
1
Even at extreme levels of wind and solar, performance meets criteria.
No under‐frequency load shedding (UFLS).
Interconnection frequency response > 840 MW/0.1Hz obligation in all cases.
Case FR (MW/0.1Hz)
Base 1352
High Mix 1311
Extreme 1055
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Frequency Control on Wind Plants Improves Performance
Light Spring High MixLight Spring High Mix with governor control*Light Spring High Mix with inertial control*Light Spring High Mix with both controls
Disturbance: Trip 2 Palo Verde units (~2,750MW)
40% of wind plants (i.e., new ones)had these controls, for a total of 300 MW initial curtailment out of 27GW production.
123
4
1
2
34
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Transient Stability in Northeast Region of West
L
Aeolus 500kV
Large Coal Plants
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LightSpringBase
Coal Displacement in Light Spring Scenarios
LightSpringHigh Mix
LightSpringExtremeSensitivity
LightSpringBase
LightSpringExtremeSensitivity
LightSpringHigh Mix
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Dave Johnson Voltage
Light Spring BaseLight Spring High Mix Light Spring ExtremeLight Spring Extreme with synchronous condenser conversion
Synchronous Condenser Conversion Results in Acceptable Performance in Extreme Sensitivity
Reinforcements for Extreme sensitivity: 3 condensers total ~1700MVA plus ~500 MVArshunt banks.
Disturbance: Aeolus bus fault and line trip
1
3
2
4
1
2
3
4
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Composite Load Model
Details of load and distribution system, and proximity of distribution connected PV to the load is important, but historically ignored.
4 kinds of motor models
UVLS = under voltage load sheddingUFLS = under frequency load shedding
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Load Model Affects Performance More than High Penetration Wind and Solar
Heavy summer with standard load modelHeavy summer with composite load model
Disturbance: Midway‐Vincent fault and line trip
1
2
2
1
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Study Conclusions
• With good system planning, sound engineering practices, and commercially available technologies, the Western Interconnection can withstand the crucial first minute after grid disturbances with high penetrations of wind and solar.
• Local stability, voltage, and thermal problems can be addressed with traditional transmission system reinforcements (e.g., transformers, shunt capacitors, local lines).
• Non‐traditional frequency‐responsive controls on wind, utility‐scale solar PV, CSP plants, and energy storage are effective at improving system performance.
• Load modeling assumptions can have as much impact on system performance as high penetrations of wind and solar. Accurate modeling of load, as well as renewable generation, is extremely important when analyzing high‐stress conditions.
Western Wind and Solar Integration Study Phase 3a –Low Levels of Synchronous Generation
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WWSIS 3 Follow‐on Analysis
Refine WWSIS 3 databases 5.1GW CSP replaced by utility‐scale PV WECC REMTF second generation generic renewable generation dynamic models1
Update transmission topology
Transient stability focus Wyoming wind exporting region
1) http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000003002006525
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Light Spring Study Scenarios
Base Case High Mix Extreme
Wind (GW) 19.2 25.5 30.9
PV (GW) 3.9 17.5 20.4
CSP (GW) 0.9 1.2 1.4
DG (GW) 0.00 11.7 10.1
Others (GW) 71.7 43.6 34.9
Total (GW) 95.7 99.4 98.1
Penetration (% of US generation dispatch)
25.0% 56.2% 64.4%
Generation Production (GW) Summary
US WECC only
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High Mix & Extreme Scenarios
Production in GW. Same wind and solar capacity in both cases.
High Mix Extreme
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Study Scenarios in Context
0
10
20
30
40
50
60
1 10001 20001 30001 40001 50001 60001 70001 80001 90001 100001
Wind an
d Solar P
enetratio
n (%
of a
ll gene
ratio
n)
5 min period
Penetration duration curves from WWSIS 2.
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Transient Stability in Northeastern WECC
L
Aeolus 500kV
Large Coal PlantsGateway South 500kV transmission project
Gateway West 500kV transmission project
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Significant Coal Displacement
From stability and power flow perspective, no difference between retirement and decommitment.
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Response to Aeolus Fault
0
0.2
0.4
0.6
0.8
1
1.2
0 0.5 1 1.5 2
Wyodak 230kV Vo
ltage (p
u)
Time (Seconds)
High Mix Extreme
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System Separation under Extreme Case
Injected power is too high relative to the system’s ability to accept the power.
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Mitigation
• Synchronous condensers (shown to work in WWSIS 3)• Eliminate pre‐disturbance overloads• Low voltage power limit (LVPL) during fault• OEM specific weak grid controls• Combinations of the above
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Response to Aeolus Fault with Mitigation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.5 1 1.5 2
Wyodak 230kV Vo
ltage (p
u)
Time (Seconds)
Extreme
Extreme without pre‐disturbance overloads
Extreme without pre‐disturbance overloads with aggressive LVPL
Extreme without pre‐disturbance overloads with less aggressive LVPL
Extreme without pre‐disturbance overloads with OEM weak grid controls
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Response to Aeolus Fault with Mitigation
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 0.5 1 1.5 2
Wyodak 230kV Vo
ltage (p
u)
Time (Seconds)
High Mix
Extreme without pre‐disturbance overloads with less aggressive LVPL
Extreme without pre‐disturbance overloads with OEM weak grid controls
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Delayed Post‐Fault Active Power Recovery
0
20
40
60
80
100
120
140
0 0.5 1 1.5 2
Exam
ple Wind Plant P
ower (M
W)
Time (Seconds)
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Study Conclusions
• The integration of large amounts of wind generation with the associated displacement of substantial thermal generation is technically feasible using commercially available wind power plant controls and limited, standard technology grid support.
• The studied conditions were highly stressed but not comprehensive, good system engineering practice as the system is built out will ensure continued reliability of the power system.
Thank you!
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WWSIS Referenceswww.nrel.gov/electricity/transmission/western_wind.html
Phase 1Executive Summary: http://www.nrel.gov/docs/fy10osti/47781.pdfFull Report: http://www.nrel.gov/docs/fy10osti/47434.pdf
Phase 2 Executive Summary: http://www.nrel.gov/docs/fy13osti/58798.pdfFull Report: http://www.nrel.gov/docs/fy13osti/55588.pdf2‐page Fact Sheets: http://www.nrel.gov/docs/fy13osti/57874.pdf
http://www.nrel.gov/docs/fy13osti/59064.pdf
Phase 3 Executive Summary: http://www.nrel.gov/docs/fy15osti/62906‐ES.pdfFull Report: http://www.nrel.gov/docs/fy15osti/62906.pdf2‐page Fact Sheets: http://www.nrel.gov/docs/fy16osti/65302.pdf
http://www.nrel.gov/docs/fy16osti/65410.pdf
Phase 3a Full Report: http://www.nrel.gov/docs/fy16osti/64822.pdf