Aidan Tuohy Technical Leader/Project Manager, EPRI ERCOT Emerging Technology Working Group (ETWG) 09/24/2014 Transmission System Considerations for Integrating Distributed Resources

2 © 2014 Electric Power Research Institute, Inc. All rights reserved. Overview Background and Potential Bulk System Impacts of Distributed Energy Resources (DER) Benefit/Cost Assessment Framework for Integration of DER Interconnection Requirements for DER

3 © 2014 Electric Power Research Institute, Inc. All rights reserved. How much PV Is Possible? DOE SunShot Initiative Scenarios… Source: NREL, “Sensitivity of Rooftop PV Projections in the SunShot Vision Study to Market Assumptions” Optimistic, but policy objective PV assumptions, leads to Rooftop PV of 120 GW in 2030 & 240 GW in 2050.

4 © 2014 Electric Power Research Institute, Inc. All rights reserved. Inverter – Role in Power System

5 © 2014 Electric Power Research Institute, Inc. All rights reserved. Increasing amounts of distributed energy resources –Solar PV, –Electric Vehicles –Demand Response –Distributed storage –Other distributed generation As penetration level of these resources increases, they may impact on bulk system reliability- impacts may include: –Ramping and Variability Impacts –Reactive Power Control –Loss of DR During Low Frequency and Voltage Conditions –System Protection Considerations –Under Frequency and Under Voltage Load Shedding (UFLS/UVLS) –Visibility/Controllability of DR at Bulk System Level Distributed energy resources will impact bulk system operations

EPRI Integrated Grid Assessing Costs and Benefits of DER

7 © 2014 Electric Power Research Institute, Inc. All rights reserved. Integrated Grid – Phase II 3 Key Areas & Research Challenges Benefit - Cost Framework Interconnection Technical Guidelines Grid Planning & Operations Completed Draft of Benefit-Cost Framework Presently under Internal EPRI Review

8 © 2014 Electric Power Research Institute, Inc. All rights reserved. Hosting Energy Capacity Distribution System Bulk System Customer or Owner Cost/Benefits Societal Costs/Benefits Benefit/Cost Core Assumptions Adoption/ Deployment Scenarios Market Conditions Resource Adequacy Flexibility Operational Practices & Simulation Transmission Performance Transmission Expansion System Net Costs System Benefits Reliability Integrated Grid: Benefit Cost Framework DRAFT

9 © 2014 Electric Power Research Institute, Inc. All rights reserved. Integrated Grid: Bulk System Analysis 1 RESOURCE ADEQUCY 2 FLEXIBILITY 3 OPERATIONAL SIMULATION 4 TRANSMISSION PERFORMANCE 5 TRANSMISSION EXPANSION DRAFT

10 © 2014 Electric Power Research Institute, Inc. All rights reserved. How Will Future Electricity Resource Needs Change? Ancillary services and capacity may become more valuable to operators causing a shift in market design Ancillary services and capacity may become more valuable to operators causing a shift in market design BeforeAfter? EirGrid Considerations Irish Simulation Study + 40% renewable scenario + w/ & w/o add’l A/S set (inertia, ramp, VAR res) Change in A/S Costs $60M  $300M Regulator rejected study, but gives ballpark of potential changes EirGrid Considerations Irish Simulation Study + 40% renewable scenario + w/ & w/o add’l A/S set (inertia, ramp, VAR res) Change in A/S Costs $60M  $300M Regulator rejected study, but gives ballpark of potential changes

Interconnection Requirements Examples of Potential Requirements and Performance from DER

12 © 2014 Electric Power Research Institute, Inc. All rights reserved. General Reliability Concerns Reliability Functions Reactive power/voltage control Active power control –inertia/primary freq response Disturbance performance –voltage & frequency ride through Other Considerations Inverter capabilities Available headroom for wind/PV Distributed Inverter-Based Generators must supply Reliability Services as they Displace Conventional Sources of those reliability services!

13 © 2014 Electric Power Research Institute, Inc. All rights reserved. Can Inverter-Based Generation be equipped with Grid Support Functionality? What functionalities are needed and how should they be required? Key Questions

14 © 2014 Electric Power Research Institute, Inc. All rights reserved. Low Voltage Ride Through Impact (PJM) Source: Mahendra Patel, PJM.

15 © 2014 Electric Power Research Institute, Inc. All rights reserved. Updated Interconnection Rules Reduces Risk of Frequency Instability Grid Frequency in Hz Time in Seconds Source: T. K. Vrana (2011) Previous Interconnection Rules Updated Interconnection Rules German Operating Frequency Limit Germany 15,000 PV systems Sized 10kW+ 9 GW Nominal Power Over 3 – 4 years Costing €70 – 180 Million Retrofitting/ Replacing

16 © 2014 Electric Power Research Institute, Inc. All rights reserved. Dynamic Assessment of potential impacts Impact on Voltages :  Delay in voltage recovery  With and without voltage ride-thru Impact on Voltages :  Delay in voltage recovery  With and without voltage ride-thru Impact on Frequency:  Reduction in system inertia due to change in generation mix  PV drop out due to large voltage disturbance (as per IEEE 1547) Impact on Frequency:  Reduction in system inertia due to change in generation mix  PV drop out due to large voltage disturbance (as per IEEE 1547)

17 © 2014 Electric Power Research Institute, Inc. All rights reserved. Changes in “Response to Abnormal Voltages” IEEE IEEE 1547a Similar requirement for frequency

18 © 2014 Electric Power Research Institute, Inc. All rights reserved. Voltage Regulation – Reactive Power Support Power factor setting Constant VAR consumption/injection Volt-VAR control Voltage Setpoint Can support distribution and/or transmission

19 © 2014 Electric Power Research Institute, Inc. All rights reserved. Real power control, ramping, and curtailment 100% 75% 25% In 4 seconds In 6 seconds

20 © 2014 Electric Power Research Institute, Inc. All rights reserved. Today’s Smart Inverter Technology Enabling Changes in Grid Codes Inverters converts DC energy to AC energy and interface the generating plant with electricity grid Traditional Inverter Functionality Smart Inverter Functionality Matching plant output with grid voltage and frequency Providing safety by providing unintentional islanding protection Disconnect from grid based on V/f set points Active power reduction in case of over-frequency Fault Ride Through (FRT) Reactive power and voltage support Communication with grid Many more DC PowerAC Power

21 © 2014 Electric Power Research Institute, Inc. All rights reserved. What if Standards are not Changed? Source: DOE SunShot Vision Study (Total PV Capacity in U.S – 2030) Not changing is not an option! Question is when? Retrofitting inverters in a later date could be pretty expensive

22 © 2014 Electric Power Research Institute, Inc. All rights reserved. Summary Increasing levels of Distributed Energy Resources –Getting out ahead is important to be able to fully utilize these new resources Need framework to understand costs/benefits –EPRI Integrated Grid effort developing framework –Should inform market development Inverter based generation can behave in ways desirable to system operations –Need to specify requirements –EPRI white paper series coming out soon

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