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FAILURE TO FOLLOW DISPATCH INSTRUCTIONS

Agenda Item #2 MC Mtg. 10/9&10, 2001. FAILURE TO FOLLOW DISPATCH INSTRUCTIONS. Appropriate tolerance band for setting flag. Current Method.

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FAILURE TO FOLLOW DISPATCH INSTRUCTIONS

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  1. Agenda Item #2 MC Mtg. 10/9&10, 2001 FAILURE TO FOLLOW DISPATCH INSTRUCTIONS Appropriate tolerance band for setting flag

  2. Current Method • Absolute value of the difference between the sum of actual generation over the previous 3 dispatch solutions and sum of Desired Dispatch Points must be less than 3% of LOL or 3 MW, whichever is greater • Current method became effective 9/1/2001

  3. Problems Raised with current method • Tolerance level of absolute value of 3% over 3 Dispatch Periods effectively results in a 1% tolerance per Dispatch Period • Use of realistic unit ramp rates & telemetering accuracy alone can exceed effective tolerance of 1% • Consequences are severe (exclusion from both ECP calculation & NCPC)

  4. IMPACT OF CURRENT METHOD • Nearly all units in control mode 4 have at least some violations • On 9/28/2001 more than 40 units were flagged for at least one dispatch period. • The ISO has concluded that this level of failure indicates a significant problem with the current tolerance level (3% of HOL compared to the absolute value of the difference between generation for 3 dispatch periods and DDPs for the same 3 dispatch periods

  5. Rationale for Current Method • Failure to Follow Dispatch Instructions was a significant problem when Electronic Dispatch was being implemented (especially instructions to reduce output when ECP was high) • Modeled after NYISO • 3MW limit was added to provide a reasonable tolerance level for small units

  6. PG&E Proposal • Absolute value of (the difference between the sum of the actual generation over the previous 5 dispatch solutions and the sum of the Desired Dispatch Points for those 5 solutions) divided by 5 must be less than or equal to the greater of 3% of HOL or 3 MW.

  7. Rationale for PG&E Proposal • An excessive number of generators are being flagged with Failure to Follow Desired Dispatch and are precluded from setting RTMP or being eligible for NCPC

  8. ISO Comments on PG&E Proposal • The ISO agrees that experience to date suggests the current tolerance is too tight • ISO supports PG&E’s proposal because: • The ISO agrees that the tolerance should be increased to an effective level of 3% per dispatch period; • Increasing the number of periods used in the rolling average calculation would not adversely affect reliability or markets but may, like the current use of 3 periods or any rolling average, cause the ECP in one hour to be affected by violations in an earlier hour.

  9. Three Units to Illustrate Impact

  10. Simplified illustration • Spreadsheets in handout creates 3 units and applies both methods

  11. ISO RECOMMENDATION • Vote to Recommend the PG&E proposal to the NPC for filing with the FERC • Continue to track data for adequacy of screen.

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