1. A Summary on Probabilistic Workshop held on September 9, 2014 Milorad Papic (RAWG Chair) Salt Lake City, January 13, 2015

2. Outline 1.Workshop Goals 2.Topics covered 3.Tools/Methodologies 4.Summary of the Results 5.Next Steps 2 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

3. 1. Workshop Goals 3 W ESTERN E LECTRICITY C OORDINATING C OUNCIL 1.Present practical experience in evaluating adequacy of generating capacity by different regions in the Western interconnection. 2.Learn how uncertainties associated with load, intermittent energy sources and forced and maintenance outages on generating units and transmission facilities have been taken into consideration. 3.How the ongoing integration of variable resources such as wind and solar might change the present methodologies and tools for computing the adequacy of the system?

4. 2. Topics Covered 4 W ESTERN E LECTRICITY C OORDINATING C OUNCIL Generation Reliability Concepts - Milorad NERC GTRPM Methodology - Milorad Reliability Metrics LOLE, EUE, LOLH - Milorad Reliability Metrics Calculation – Simple Practical Examples - Milorad SCE’s System and Flexibility Analysis for the 2014 LTPP Phase 1A – Megan Mao NW Resource Adequacy - Robert Diffely BC Hydro’s Probabilistic Planning – Nan Dai A Direct High Speed Calculation Procedure For Determining LOLE, LOLH, and EUE For Fossil, Wind, and Solar Generation With A Suggested Procedure For Also Including Transmission Constraints - G. Preston IEEE Working Group Loss-Of-Load-Expectation Best Practices – Brandon Heath

5. 3. Tools/ Methodologies Tools: WECC (PROMOD, Grid View) SCE (PLEXOS, REFLEX) North West (GENESYS) BC Hydro (LOLA, RISK, MECORE) ATC (P33) 5 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

6. 3. Tools used by WECC The PROMOD is a security-constrained economic dispatch (SCED) software package used widely in the power industry. Studies performed in PROMOD typically analyze an entire year, hour-by- hour, for the entire Western Interconnection. It enables modeling of energy-limited resources over the entire year. The model allows the assessment of performance of multiple scenarios because of the ease of data manipulation and changes in study assumptions. It has the capability to model uncertainties related to thermal generator outages, hydro, wind, and load using a Monte Carlo convolution approach. GridView is a software application developed by ABB, Inc., to simulate the economic dispatch of an electric power system while monitoring key transmission elements for each hour. 6 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

7. 3. Tools used by SCE 7 W ESTERN E LECTRICITY C OORDINATING C OUNCIL The PLEXOS model is an electricity market simulation model developed by Drayton Analytics. PLEXOS includes a comprehensive Monte Carlo model for modeling of both generators and transmission forced outages. The program’s solution simulation engine is based on proven mathematical programming techniques that ensure the simulation outcomes are robust and consistent across scenarios. Modeling is performed in PLEXOS; for each sample, considers unit commitment and dispatch over 24 hours. The Renewable Energy Flexibility (REFLEX) model can be characterized as a detailed Monte Carlo simulation of a system under a wide range of operating conditions. It performs stochastic production simulation through Monte Carlo draws of load, wind, and solar production. The tool has been used for the Californian system to examine the flexibility of the system under future high variable generation scenarios.

8. 3. Tools used by NW and BC Hydro The GENESYS is a Monte Carlo-based model developed by the Northwest Power and Conservation Council (Council). The tool is used to develop a consensus-based resource adequacy framework and to perform annual resource adequacy assessments in the Northwestern region by taking into consideration many different uncertain future conditions. BC Hydro has a suite of probabilistic models to suit different needs in the areas of resource planning and operation. For long-term generation planning the loss of load analysis (LOLA), an in-house developed analytic program is used to assess the resource adequacy of BC Hydro’s generation system. In practice, analysis is done on a monthly basis to allow for the inclusion of generator maintenance schedules and fuel supply limitations. 8 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

9. 3. Tools used by BC Hydro For winter generation operations, the Excel-based RISK software was used. It includes uncertainties for both peak loads and unit forced outages. RISK uses Monte Carlo simulation to produce probability distributions for the projected system’s monthly peak- hour capacity net surplus/deficit. This allows the user to determine probabilistically if there is sufficient capacity to meet specified risk tolerances. If there is insufficient capacity, operational plans are employed to acquire additional capacity to meet the specified risk tolerance, which is currently set at 90th percentile. For composite system (generation + transmission) planning, the MECORE program is used. The program is Monte Carlo based and used to complement the deterministic N-1 analysis to maintain a reasonable system reliability level. 9 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

10. 3. Tool developed by TAC Transmission Adequacy Consulting (TAC) P33 Program is based on methodologies presented in the early 1970s by Booth and Baleriaux. These references present an exact calculation procedure for developing the cumulative probability generation outage distribution, which is now referred to as a recursive procedure. This greatly increases the speed and accuracy of calculating the reliability indices compared with the use of a binary tree (too large) or sampling (lacks accuracy and is slow to run). 10 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

11. 4. Summary of the results North West: In December 2011, the Council adopted the LOLP methodology and established a 5 percent LOLP standard. There have been two assessments (2017 and 2019) prepared by the Council under the adopted new LOLP methodology. In both of these assessments, the LOLP standard of 5 percent was not met. In 2017, the LOLP was 7 percent, and in 2019 it was 6 percent. BC Hydro: Evaluated the LOLP of the system that leads to the 14% capacity margin requirement Calculated the effective load carrying capability (ELCC) of the intermittent resources that leads to the 26% wind ELCC 11 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

12. 4. Summary of the results (cont..) SCE: For the High Load Scenario, SCE finds 6250 MW of net shortfall. “90% confident that the correct estimate of stage 3 emergencies is between 34 and 37” With no additional authorizations, SCE’s analysis predicts 35 shortfall events in 10 years Approximately 6250 MW of resources are needed to achieve a one event in 10 year reliability standard 12 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

13. 4. Summary of the results (cont..) WECC: Overall results, the 2016 EUE is expected from roughly nil in the SWSG subregion to roughly 96 MWh for the entire year in the NWPP subregion. The 2018 EUE is expected from roughly one MWh in the SWSG subregion to roughly 548 MWh for the entire year in the RMRG subregion. In both assessments, none of the regions LOLH exceeds the rough industry guideline of no more than 1 day in 10 years cumulative or 0.1 day per year. 13 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

14. 5. Next Steps Continue share study results performed by WECC entities with RAWG Address Planning for Adequate Reliability under High Penetration of Renewable Calculating reliability indices (used by Reliability Tools as an input) from outage data collected in TADS and GADS 14 W ESTERN E LECTRICITY C OORDINATING C OUNCIL

15. Questions? Milorad Papic Chair, Reliability Assessment Work Group mpapic@idahopower.com 15 W ESTERN E LECTRICITY C OORDINATING C OUNCIL