1. Western Wind and Solar Integration Study - Phase 3
Kara Clark, NREL Nick Miller, Miaolei Shao, Slobodan Pajic, Rob D’Aquila, GE
July 15, 2014

2. Western Wind and Solar Integration Study
Phase 1 - Can we integrate high penetrations of wind and solar into the Western Interconnection? What do we need to do to accommodate this?
Phase 2 – What is the impact of high penetration wind and solar on the rest of the generation fleet? Specifically, what are the costs of cycling, and the emissions impacts of cycling? Do wind and solar differ in their impact?

3. WWSIS Phase 3 Project Objectives
Examine Western Interconnection large scale stability and frequency response with high wind and solar penetration
Identify means to mitigate any adverse impact (advanced controls, transmission, storage, etc)
Investigate whether power system reliability can be maintained with high wind and solar penetration

4. Building the Study Scenarios
WECC power flow and dynamic databases
2022 Light Spring, 2023 Heavy Summer
WWSIS Phase 2 renewable scenario
High Mix 33% wind and solar annual energy (½ and ½)
Mine WWSIS Phase 2 PLEXOS results
Time periods that match power flow cases,
High levels of wind and solar generation,
Balance of fleet commitment and dispatch
Composite load model including rooftop PV
Defined 4 regions for reporting
Northwest = Northwest
California = IID, LADWP, PGE, SDG&E, SCE
Northeast = PACE, ID, MT, Sierra, WAPA UM
Desert Southwest = AZ, El Paso, NV, NM, WAPA RM, PSCo

5. Wind and Solar Siting

6. WWSIS 3 Light Spring scenarios
Reference Case High Renewable Case
~21GW Wind, ~5GW Solar 28% penetration*
~27GW Wind, ~25GW Solar 57% penetration*
* = % of instantaneous load

7. WWSIS 3 Extreme Light Spring scenario
Reference Case Extremely High Renewable Case
~21GW Wind, ~5GW Solar 28% penetration*
High Renewable Case
~33GW Wind, ~32GW Solar 69% penetration*
~27GW Wind, ~25GW Solar 57% penetration*
* = % of instantaneous load

8. Composite Load Model (CMPLWG)
PLnet M
Pma
QLnet
Loadflow
Bus M
Pmb
PLagg M
Pmc M
Pdg
Pmd
PV gen.
Qdg
Electronic
Pel
UVLS
UFLS
Static
Pst

9. Scope of Analysis Not comprehensive or exhaustive
Frequency response focused on loss of 2 Palo Verde units
Transient stability focused on loss of Pacific DC Intertie and fault on new bus in wind rich part of Wyoming
Lots of monitoring
Standard performance criteria
Sensitivity analysis of mitigation measures

10. Frequency Response Analysis
Evaluate frequency response to loss of generation
Large central station
Distributed generation
Apply frequency controls to wind plants
Apply frequency controls to solar plants
Add energy storage
Illustrate impact of re-dispatch and/or de-commitment
Headroom depletion

11. Frequency Response Obligation
BAL 003-1
Approximate FRO for 4 regions and 20 areas.
Actual FRO is BA based

12. Preliminary Frequency Response Results
Reference High Renewables
Extremely High Renewables
Frequency nadir
59.61
Settling frequency
59.81
Reference
High Renewables
Extremely High Renewables
FRO FR Kt
WECC
840
1352
0.46
1311
0.42
1065
0.38
California
296
305
0.34
312
0.33
295
0.32
DSW
220
215
0.44
119
0.27 97
0.22
Northeast 82 61
0.26 47
0.3 51
Northwest
131
434
0.62
483
280
0.53
2 Palo Verde unit outage
Preliminary. Not for Citation or Further Distribution.

13. Apply Frequency Controls to Wind Plants
5% primary frequency response (aka APC = active power control)
Apply to new wind plants loaded <= 95% of rating
No change to power flow, assume wind speed is sufficient to deliver 5% more
~900 MW headroom
Controlled inertial response
Combination of APC and controlled inertial response

14. High Renewables Frequency Response
High Renewables HR + Wind Controlled Inertial Response
HR + Wind Active Power Control
HR + Wind Controlled Inertial Response & APC
Preliminary. Not for Citation or Further Distribution.

15. Apply Frequency Controls on Solar Plants
5% primary frequency response
Apply to new utility scale PV only
~820 MW curtailment
Aggressive control
No controlled inertial response

16. High Renewables Frequency Response
High Renewables HR + Solar Governor Response
Preliminary. Not for Citation or Further Distribution.

17. Transient Stability Analysis
Evaluate stability under heavy summer conditions in response to
PDCI outage
Broadview 500kV fault and line trip
Laramie River 345kV fault and line trip
Impact of load modeling
Analyze coal plant displacement/retirements
Aeolus 500kV fault and line trip
Extremely high renewables
Light spring
System strength
% Non-synchronous generation
Investigate possible relay impacts/issues

18. WWSIS 3 Extreme Light Spring scenario
Reference Case Extremely High Renewable Case
~21GW Wind, ~5GW Solar 28% penetration*
High Renewable Case
~33GW Wind, ~32GW Solar 69% penetration*
~27GW Wind, ~25GW Solar 57% penetration*
* = % of instantaneous load

19. New Transmission into NE part of WI
Aeolus 500kV

20. Coal Displaced/Retired
DSW
Northeast
Coal
Coal !! !!
Reference High Renewables Extremely High
Renewables
Reference High Renewables Extremely High
Renewables
Preliminary. Not for Citation or Further Distribution.

21. NE Areas Idaho (60) Montana (62) Sierra (64) PACE (65)
Reference High Extremely
Renewables High
Renewables
Reference High Extremely
Reference High Extremely
Preliminary. Not for Citation or Further Distribution.

22. WYODAK 230 kV Bus Voltage Reference High Renewables
Extremely High Renewables
Extremely High Renewables with Reinforcements
Preliminary. Not for Citation or Further Distribution.

23. Dave Johnson Synchronous Condenser Conversion
Reference Extremely High Renewables with Reinforcements
Power (MW)
Reactive Power (MVAr)
Reference Extremely High Renewables with Reinforcements
Preliminary. Not for Citation or Further Distribution.

24. Systemic concern about future low levels of synchronous generation
System Strength
Systemic concern about future low levels of synchronous generation
EirGrid monitors “system non-synchronous penetration”, currently limited to <50%, potential to raise limit to <75%
Also an issue in west Texas, Brazil, Australia
Fault currents

25. Synchronous vs. Non-synchronous Commitment
California
DSW
Northwest
Northeast
Condensers
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
Preliminary. Not for Citation or Further Distribution.
HS = heavy summer
LSP = light spring

26. System Non-Synchronous Penetration
~66% SNSP without condensers
~ 61% with condensers
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS Reference
HS High Renewables
LSP Reference
LSP High Renewables
LSP Extremely High
HS = heavy summer
LSP = light spring
Preliminary. Not for Citation or Further Distribution.

27. Light Spring Fault Currents
Location
Reference
Extremely High Renewables
Dave Johnson 230 kV
19.7 kA/7,730 MVA
10.7 kA/4,260 MVA
Populus 345 kV
25.1 kA/15,000 MVA
20.1 kA/12,000 MVA

28. Observations on high coal displacement / weak grid
Dynamic models really need to be right when wind and solar are the dominant source of generation
WECC has longstanding best practice to keep dynamic models up-to-date
Wind and solar plant modeling needs to be held to the same level of accountability in high penetration future
More on investigation of sensitivity to WTG control specifics and of modeling implications.
Local problems will occur
Good transmission planning practice is needed, especially for voltage management
There is no obvious reason why voltage and thermal problems can’t be solved by conventional methods – but they will need to be solved!
Further investigation of weak grid aspects needed
Maximum fraction of non-synchronous generation the limit on wind and solar now in Ireland, Brazil, etc
Potential barrier to high penetration wind and solar in the US

29. WWSIS 3 Next Steps Analysis done Draft final report this summer
In-person TRC meeting in October
Final report by end of December

30. Thank You! Kara Clark National Renewable Energy Laboratory