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Steady-State Working Group: Resource Modeling Discussion Wes Woitt September 27 th , 2011

Steady-State Working Group: Resource Modeling Discussion Wes Woitt September 27 th , 2011. Areas of Concern. This year resource data is being pulled from RARF submittals into SSWG base cases TSPs identified differences between historical models and RARF data in the following:

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Steady-State Working Group: Resource Modeling Discussion Wes Woitt September 27 th , 2011

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  1. Steady-State Working Group: Resource Modeling Discussion Wes Woitt September 27th, 2011

  2. Areas of Concern • This year resource data is being pulled from RARF submittals into SSWG base cases • TSPs identified differences between historical models and RARF data in the following: • Reactive capability • GSU data • Generator impedances and machine ratings (DWG to cover)

  3. Reactive Capability (Generator Reactive Limits) • Planning studies need to model realistic operational limits, not theoretical limits • Qmax & Qmin values are very important for calculating system behavior • Steady-state voltage studies • Voltage stability studies • Dynamic system studies • Post-event analysis of major blackouts inevitably showed planning models with unrealistic reactive limits were contributors to false sense of security

  4. Why do we care? Steady-State Voltage Stability Studies are affected • Larger QMAX values for generation in the Houston Area result in an optimistic voltage stability limit. • Results in a larger voltage stability margin and lower voltage collapse point than actually exists. • Indicates over 900 MW more of import capability into the Houston area.

  5. Why do we care? Transient Voltage Recovery studies are affected CenterPoint Energy System dynamic bus voltages after a large disturbance Larger QMAX and MBASE data from July TP case Historical QMAX and MBASE data Results in 0 MW of Under Voltage Load Shedding Results in 3824 MW of Under Voltage Load Shedding

  6. Biennial Reactive Test Review Protocol 8.1.1.2.1.4(2) The Generation Resource Entity shall conduct reactive capacity qualification tests to verify the maximum leading and lagging reactive capability of all Generation Resources required to provide VSS. Reactive capability tests are performed on initial qualification and at a minimum of once every two years. • Overview of lagging test (leading is similar) • From test to base case • From test to RARF • Examples of errors in translation

  7. Overview of Lagging Test Data Sheet

  8. Test Data used in Planning

  9. SSWG Procedure Manual How is Q Max Calculated? • Qmax is the maximum net lagging MVAr observed at the low side of the generator step up transformer when the unit is operating at its maximum net dependable MW capability. • Qmax is calculated from the lagging CURL value by subtracting any auxiliary MVAr loads and any Load Host MVAr (Self Serve) load served from the low side of the generator step up transformer. •  Numerical Example • Lagging CURL = 85 MVAR • Lagging test value = 80 MVAR (Gross) • Auxiliary Load = 5 MVAR •  Qmax is 85 – 5 = 80 MVAR Use the CURL value here if the test value is equal to or greater

  10. EXAMPLE: From Test Data to Planning Case MAX CURL 348 MVAR AUX LOAD 37 MW-> 21.5 MVAR @ 0.87 PF IN Planning Case QMAX: 348-21.5= 326.5 MVAR

  11. Planning Tab of RARF

  12. RARF Worksheet 7.0 Reactive Capability The Reactive Capability section requires the submittal of the manufacturer’s capability curve as well as the 9-point curve values in the RARF. This information will be used to validate test data and should be the best design information available – including all reactive limitations. ERCOT will continue to require bi-annual testing, and this data will be used operationally.

  13. Example: Using Test Data to fill out RARF POINT 1 -> MW1 in RARF POINT 6 -> MW4 in RARF Point 1 Point 2 Point 3 Point 4 Point 5 Point 6

  14. Questionable Test Data Reactive Load??? NET Gen Reactive= Gross- AUX Load

  15. SAMPLE DATA NEW D CURVE DOES NOT SHOW 200 MVAR LIMIT SHOWN EARLIER

  16. Example: Difference Between RARF &Test Data D CURVE RARF data points do not match test or D curve

  17. Generator Step-Up Transformer Data from RARF Transformer TAB of RARF July ’11 Planning Case Using RARF data: Data from latest DSB Case There are some discrepancies in GSU Tap and Automatic Voltage Control settings

  18. Where To Get Additional Information ? • RARF Glossary • Contact Wholesale Client Services RARF Asset Registration Guide

  19. Conclusion • Modeling realistic reactive limits on generators is critical to transmission planning studies • The realistic limits come from the reactive tests • RARF data needs to reflect reactive tests • Generator Step-Up Transformer data needs to be input as fixed with the actual tap setting

  20. Questions

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