Power Supply Adequacy Assessment ModelMethodology Review January 29

Power Supply Adequacy Assessment Model/Methodology Review January 29, 2010 Steering Subcommittee Meeting January 29, Steering 2010 Resource Adequacy Committee

Outline • Model Validation – Benchmarking Process – Sample Historical vs. Simulated Dispatch • Methodology Review – Current Adequacy Metric: LOLP – The Problem with LOLP – LOLP Subcommittee Suggestions – Next Steps January 29, 2010 Resource Adequacy Steering Committee 2

Model Validation • HYDSIM vs. actual monthly generation • GENESYS vs. HYDSIM hydro generation output • Hydro peaking calibration – Trapezoidal Model/HOSS/Capacity Survey • Check random variable distributions – Water, wind, forced outage, load/temperature • Simulated thermal dispatch vs. historical dispatch • Simulated hydro dispatch vs. historical dispatch • Simulated dispatch vs. scheduler’s perspective January 29, 2010 Resource Adequacy Steering Committee 3

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Sample Comparison of Historical vs. Simulated Hydro Dispatch • Hourly hydro dispatch is highly dependent on hourly load shape • Historical and Genesys hydro load following is consistent • Illustrative only – based on old data and F&W constraints January 29, 2010 Resource Adequacy Steering Committee 5

Methodology Review Current Adequacy Metric: LOLP January 29, 2010 Resource Adequacy Steering Committee

GENESYS Simulation Illustrative Example Only Cold Hydro Limited January 29, 2010 Resource Adequacy Steering Committee 7

Curtailment Events (Peaking problems and energy shortages) Each event has a peak and duration. January 29, 2010 Resource Adequacy Steering Committee 8

What do we Count? • • • Ideally, we count “significant” events (those that we want to avoid) Energy threshold (or contingency resource) is 1, 200 MW for one day or 28, 800 MW-hours from Dec-Mar Capacity threshold (or contingency resource) is 3, 000 MW in any hour from Dec-Mar and from Jun-Sep January 29, 2010 Resource Adequacy Steering Committee 9

Curtailment Events (non-events not shown) January 29, 2010 Resource Adequacy Steering Committee 10

Loss of Load Probability Simulated 300 winters (December through March) Out of 300 winters, 15 had an average curtailment greater than 10 MW-seasons, which means that the Winter Loss of Load Probability (LOLP) = 15/300 = 5 percent January 29, 2010 Resource Adequacy Steering Committee 11

Energy LOLP (Sum of Curtailed Energy Dec-Mar) January 29, 2010 Resource Adequacy Steering Committee 12

The Problem with LOLP January 29, 2010 Resource Adequacy Steering Committee

Potential Problem with LOLP Same LOLP – Bigger Magnitude January 29, 2010 Resource Adequacy Steering Committee 14

Potential Problem with LOLP Lower LOLP – Bigger Magnitude January 29, 2010 Resource Adequacy Steering Committee 15

LOLP Subcommittee Report and Recommendations January 29, 2010 Resource Adequacy Steering Committee

LOLP Subcommittee Report • Clearly define all reserve requirements – Operating reserves – Planning reserves – Wind integration reserves • • Determine which reserve curtailments count toward LOLP Add temperature-correlated wind as a random variable Decouple temperature and water condition Define a “contingency” resource for each month of the year instead of defining threshold events • Record curtailment events across all months of the year • Consider using other adequacy metrics • Continue to assess climate change impacts January 29, 2010 Resource Adequacy Steering Committee 17

LOLP Review Status • Reserves – Work being done by PNUCC committee • Temperature-correlated wind – BPA working on a test data set • Decouple temp and water – Done • Contingency resource – Work needs to be assigned • Annual metric – Not yet started • Other metrics – BPA draft methodology – PSRI review • Climate change – Ongoing January 29, 2010 Resource Adequacy Steering Committee 18

Next Steps January 29, 2010 Resource Adequacy Steering Committee

Possible Modifications to the Current Method • Replace LOLP with an alternative metric • Use LOLP in conjunction with an alternative adequacy metric • Use LOLP in conjunction with the magnitude of the most severe event (or an average of the worst 10% of events) January 29, 2010 Resource Adequacy Steering Committee 20

Examples of Other Adequacy Metrics • LOLE: loss of load expectation (%) – Number of hours with curtailment divided by the total number of hours simulated – Can be more intuitive, i. e. 99. 5% reliable – Does not address magnitude • EUE: expected unserved energy (MW-hr) – Average amount of unserved energy per year – Lacks specific information about severe events January 29, 2010 Resource Adequacy Steering Committee 21

Work Plan • PSRI review complete by early 2010 • Benchmark GENESYS by early 2010 • Tech Committee propose new metric and threshold by April of 2010 • Use new metric to assess 3 and 5 year adequacy by June 2010 January 29, 2010 Resource Adequacy Steering Committee 22