Managing Intermittent Resources Black Sea Regional Transmission Planning Project November 8, 2010

1. Managing Intermittent ResourcesBlack Sea Regional Transmission Planning ProjectNovember 8, 2010

2. Topics • Current and Projected Midwest ISO Wind Penetration • Short and Long-Term Initiatives to Accommodate Intermittent Fuel • Dispatchable Intermittent Resources • Ramp Management (Load Following) • Midwest ISO Wind Generation Forecast Overview • Current Capabilities and Functions • Accuracy

3. Installed Wind in Midwest ISO 50,000+ Integration of MidAmerican Energy on September 1, 2009, +1530MW of wind 3

4. Wind Generation within Midwest ISO • Wind Generation Registered Capacity as of July 1, 2010 • Total registered wind generation capacity: 8168.65 MW • Wind resource represents 5.6% of the total registered capacity • Wind Generation Distribution • Wind Output Statistics • On average, wind resources generate at 30% of its total capacity • Historically wind generation output ranges from 1% to 72% of its total capacity 4

5. Midwest ISO State Renewable Portfolio Standards 1 Note: Existing Wind In-Service as of 2/01/10 1Indiana is considering 4% RPS; however, the legislation has not yet passed 5

6. Current Intermittent Resource Modeling • Currently, Intermittent Resources such as wind can’t be dispatched as part of our real-time dispatch software • 10-12 minute time lag between a resource’s output measurement and the dispatch target reflecting that output; this occurs even though near-term forecasting of resource output is widely available. • This inability to dispatch necessitates manual curtailments on a regular basisto relieve transmission constraints in various parts of the Midwest ISO system. • When this happens, LMP at the CPNode does not reflect the curtailment: pricing does not reflect transmission congestion

7. Manual Wind Curtailment for Congestion(as of September, 2010)

8. High Level: What is a Dispatchable Intermittent Resource • A DIR is very similar to a standard generation resource • Difference: Generation resource supplies Max Limit as a portal offer-parameter; Dispatchable Intermittent will provide a forecast that will be used as Max Limit • The resource IS included in the day-ahead and real-time co-optimization, and IS eligible to set price • The resource can submit offers for Energy, and will clear between Min and Max Limits, based on Economics • The resource cannot submit offers for Operating Reserves (reg, spin or supp), and will not clear Operating Reserves in day-ahead or real-time

9. Dispatchable Intermittent Offer Structure (1) • Day-Ahead Offer Structure like Generation Resource Offer Structure • Full set of limits, ramp rates, energy offer • However, no Operating Reserve Offers • Real-Time Offer Structure like Generation Resource Offer Structure, with one exception • Economic Min • Ramp Rates • Energy Offer ($/MW) (again, no Operating Reserve Offers) • Similar set of ICCP data as traditional generation • No Economic Maximum Offer

10. Dispatchable Intermittent Offer Structure (2) For RT dispatch, UDS will use a participant offered Dispatch Interval Resource-level forecast as the Economic Max, rather than an Hourly Offer Economic Max Forward Process will make Economic commitments based on RT offer structure; will use MISO-generated CP-node forecast as Max Limit

11. Dispatchable Intermittent Forecast • Primary source for Max Limit will be the participant-submitted forecast • CP-Node Level Forecast to have five-minute granularity; rolling 12 periods will be submitted via XML • Forecast needs to be independent of dispatch. Example: if wind has been dispatched down to 0, but the resource could produce 100MW if dispatched up, the forecast submittal must be 100MW. • Midwest ISO will have a CP-Node Level Forecast that will be used as a backup under scenarios where the participant forecast is unavailable

12. Dispatch Comparison: Intermittent and DIR DIR Intermittent Resource

13. Wind Generation Forecast Model Numerical Weather Prediction Models Three independent forecasts are available American Weather Service Canadian Weather Service European Weather Service Midwest ISO Wind Generation Forecast Weighted average of the 3 independent forecasts Independent forecasts are weighted by their historical performance 13

14. Wind Generation Forecast - Today Started in June 2008 Energy & Meteo (E&M) is the forecast provider Forecast details Frequency: Updated hourly for next 132 hours Granularity : CPNode Level Interval : Hourly Input Information Required by CPNode Geographic Coordinates (Latitude and Longitude) Hub Height Maximum MW Output Real-Time MW Output via ICCP Historical MW Output+ + for existing wind farm only 14

15. Wind Generation Forecast Aggregation • Bottom-up Approach • In general, Cpnode level forecast available • Physical level for Jointly Owned Units • Forecast Aggregation • Zonal level • Regional level • Market footprint level • Three Regions and Eleven Zones • 7 zones in West region • 1 zone in Central region • 3 zones in East region 15

16. Wind Generation Forecast Publishing • Day Ahead System Wide Forecast published daily http://www.midwestmarket.org/page/Day-Ahead+Wind+Forecast 16

17. Wind Generation Forecast Accuracy Commonly used measures are errors normalized to the installed capacity Standard Deviation (STD) Mean Absolute Percentage Error (MAPE) Forecast horizons used in the analysis include: Day Ahead Forecast 4 Hours Ahead Forecast Hour Ahead Forecast Forecast accuracy shown is for system wide. 17

18. Hourly Wind Forecast Accuracy * All accuracy figures are based on hourly integrated values. ** All accuracy shown are for the system wide forecast. *** All accuracy shown are raw errors which do not exclude the impacts of curtailments and/or outages. 18

19. Wind Generation Forecast Challenges • Input Data • Forecast accuracy depends heavily on quality of the input data • Missing or incomplete input data also bias future forecast • Extreme Weather Conditions • Precipitation: Snow, ice and freezing rain • Low temperature: Forecasted temperature falls below turbine operational limit • Operational Actions • Midwest ISO curtails wind generation due to transmission constraints • During very cold temperature days, wind farm operators reported significant reduction of output due to shutting down wind turbines 19

20. Wind Generation Forecast Improvements Wind Farm Owners can help us to improve the forecast accuracy Provide requested input data of good quality and on timely basis Provide the additional input data we will be discussing today Provide other relevant/useful information that will help improve forecast accuracy 20

21. Additional Input Data Better understanding of physical characteristics of wind farms Turbine types and numbers High wind cutoff thresholds – wind speed and duration Cold temperature cutoff thresholds and/or icing conditions Excessive high temperature cutoff thresholds Better communications in planning Adding/replacing/removing turbines Updating operational date Improving operational awareness Outages – Planned and forced outages Curtailment 21

22. Long-Term Issue: Ramp Management 22

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