FAILURE TO FOLLOW DISPATCH INSTRUCTIONS

Appropriate tolerance band for setting flag

Agenda Item #2MC Mtg. 10/9&10, 2001

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

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)

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

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

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.

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

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.

Three Units to Illustrate Impact

Percentage of DDPs Flagged under Existing & Proposed Methods September

EXISTING PROPOSED

Unit #1Unit #2Unit #3

75% of DDPs15% of DDPs50% of DDPs

50% 6%13%

Simplified illustration

• Spreadsheets in handout creates 3 units and applies both methods

Unit Name Actual DDP DDP-1 DDP-2 DDP-3 DDP-4 DDP-5 EXISTING METH PG&E 3%HOL or 3MW HOL following

Algonquin 200 200 200 200 200 200 200 6 200198 190 200 200 200 200 200 6 200188 190 190 200 200 200 200 6 200192 190 190 190 200 200 200 6 200189 190 190 190 190 200 200 1 1.4 6 200 y191 190 190 190 190 190 200 2 1.6 6 200 y188 190 190 190 190 190 190 2 0.4 6 200 y192 190 190 190 190 190 190 1 0.4 6 200 y191 190 190 190 190 190 190 1 0.2 6 200 y

Bacon 195 200 200 200 200 200 200 6 200185 190 200 200 200 200 200 6 200187 190 190 200 200 200 200 6 200197 190 190 190 200 200 200 6 200196 190 190 190 190 200 200 10 0 6 200 N/Y195 190 190 190 190 190 200 18 2 6 200 N/Y194 190 190 190 190 190 190 15 3.8 6 200 N/Y188 190 190 190 190 190 190 7 4 6 200 N/Y190 190 190 190 190 190 190 2 2.6 6 200 Y

Charles 200 200 200 200 200 200 200 6 200200 190 200 200 200 200 200 6 200200 190 190 200 200 200 200 6 200200 190 190 190 200 200 200 6 200200 190 190 190 190 200 200 30 8 6 200 N200 190 190 190 190 190 200 30 10 6 200 N200 190 190 190 190 190 190 30 10 6 200 N200 190 190 190 190 190 190 30 10 6 200 N190 190 190 190 190 190 190 20 8 6 200 N

DDP: Issued 5-min ago for current dispatch periodDDP-1: Issued 10 mins ago for dispatch period 5-mins agoDDP-2: Issued 15 mins ago for dispatch period 10-mins agoDDP-3 through 5 add 5 mins to previous

Unit Name Actual DDP DDP-1 DDP-2 DDP-3 DDP-4 DDP-5 EXISTING METHPG&E 3%HOL or 3MW HOL following

Algonquin 100 100 100 100 100 100 100 6 200100 110 100 100 100 100 100 6 200100 120 110 100 100 100 100 6 200100 130 120 110 100 100 100 6 200100 140 130 120 110 100 100 90 20 6 200 N110 150 140 130 120 110 100 110 28 6 200 N120 160 150 140 130 120 110 120 34 6 200 N130 170 160 150 140 130 120 120 38 6 200 N140 180 170 160 150 140 130 120 40 6 200 N

Bacon 110 100 100 100 100 100 100 6 200112 110 100 100 100 100 100 6 200121 120 110 100 100 100 100 6 200129 130 120 110 100 100 100 6 200138 140 130 120 110 100 100 2 2 6 200 y149 150 140 130 120 110 100 4 0.2 6 200 y155 160 150 140 130 120 110 8 1.6 6 200 n/y165 170 160 150 140 130 120 11 2.8 6 200 n/y175 180 170 160 150 140 130 15 3.6 6 200 n/y

Charles 102 100 100 100 100 100 100 6 200107 110 100 100 100 100 100 6 200112 120 110 100 100 100 100 6 200122 130 120 110 100 100 100 6 200132 140 130 120 110 100 100 24 5 6 200 n/y142 150 140 130 120 110 100 24 7 6 200 n152 160 150 140 130 120 110 24 8 6 200 n162 170 160 150 140 130 120 24 8 6 200 n172 180 170 160 150 140 130 24 8 6 200 n

DDP: Issued 5-min ago for current dispatch periodDDP-1: Issued 10 mins ago for dispatch period 5-mins agoDDP-2: Issued 15 mins ago for dispatch period 10-mins agoDDP-3 through 5 add 5 mins to previous

Unit Name Actual DDP DDP-1 DDP-2 DDP-3 DDP-4 DDP-5 EXISTING METH PG&E 3%HOL or 3MW HOL following

Algonquin 45 50 40 30 20 10 0 6 20055 60 50 40 30 20 10 6 20060 70 60 50 40 30 20 6 20065 80 70 60 50 40 30 6 20070 90 80 70 60 50 40 45 13 6 200 N75 100 90 80 70 60 50 60 17 6 200 N80 110 100 90 80 70 60 75 22 6 200 N85 120 110 100 90 80 70 90 27 6 200 N95 130 120 110 100 90 80 100 5 6 200 N/Y

Bacon 60 50 40 30 20 10 0 6 20080 60 50 40 30 20 10 6 20060 70 60 50 40 30 20 6 20080 80 70 60 50 40 30 6 200

100 90 80 70 60 50 40 0 6 6 200 Y100 100 90 80 70 60 50 10 4 6 200 N/Y120 110 100 90 80 70 60 20 2 6 200 N/Y120 120 110 100 90 80 70 10 4 6 200 N/Y135 130 120 110 100 90 80 15 5 6 200 N/Y

Charles 55 50 40 30 20 10 0 6 20062 60 50 40 30 20 10 6 20072 70 60 50 40 30 20 6 20081 80 70 60 50 40 30 6 20092 90 80 70 60 50 40 5 2.4 6 200 Y

102 100 90 80 70 60 50 5 1.8 6 200 Y112 110 100 90 80 70 60 6 1.8 6 200 Y123 120 110 100 90 80 70 7 2 6 200 N/Y132 130 120 110 100 90 80 7 2.2 6 200 N/Y

DDP: Issued 5-min ago for current dispatch periodDDP-1: Issued 10 mins ago for dispatch period 5-mins agoDDP-2: Issued 15 mins ago for dispatch period 10-mins agoDDP-3 through 5 add 5 mins to previous

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.