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Credit for Redispatch Scenarios Current Calculations

Credit for Redispatch Scenarios Current Calculations. NAESB BPS Meeting. August 9-10, 2011. Credit for Redispatch Small Group Charge. Review Target MF formula and Measure of Success formula currently used in IDC to verify calculations are being done correctly.

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Credit for Redispatch Scenarios Current Calculations

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  1. Credit for Redispatch ScenariosCurrent Calculations NAESB BPS Meeting August 9-10, 2011

  2. Credit for Redispatch Small Group Charge • Review Target MF formula and Measure of Success formula currently used in IDC to verify calculations are being done correctly. • Propose changes that are needed for the PFV project. • This first report provides results of the Target MF review. Still work to be done on Measure of Success review.

  3. Target MF Review • Target MFs are calculated by IDC and sent to the three markets (MISO, PJM & SPP) when they have a relief obligation. • Prior to Market Flow Threshold Field Test performed in 2007 through 2009, only used 0% MFs in the Target MF formula: • Target MF (Down to 0%) = Constrained MF (Down to 0%) + Reload - Relief Obligation • Where: • Reload = Forward Unconstrained MF (Down to 0%) – Forward Constrained MF (Down to 0%) • Constrained MF (Down to 0%) represents the actual MF reported to the IDC every 15 minutes from all generators with impacts down to 0%. • Unconstrained MF (Down to 0%) represents the theoretical MF from all generators down to 0% if redispatch had never occurred (currently set to the MF at time TLR is elevated above level 1).

  4. Target MF Review • MF Threshold Field Test, recommended a 0% MF be reported for information purposes and a 5% MF be reported for curtailment purposes. Target MF formula was modified as follows: • Target MF (Down to 0%) = Constrained MF (Down to 0%) + Reload - Relief Obligation • Where: • Reload = Forward Unconstrained MF (Down to 5%) – Forward Constrained MF (Down to 5%) • Constrained MF (Down to 0%) represents the actual MF reported to the IDC every 15 minutes from all generators with impacts down to 0%. • Unconstrained MF (Down to 0%) represents the theoretical MF from all generators down to 0% if redispatch had never occurred (currently set to the MF at time TLR is elevated above level 1). • Constrained MF (Down to 5%) represents the actual MF reported to the IDC every 15 minutes from generators with a 5% or greater impact. • Unconstrained MF (Down to 5%) represents the theoretical MF from generators with a 5% or greater impact if redispatch had never occurred (currently set to the MF at time TLR is elevated above level 1).

  5. Target MF Review • The following examples show how the Target MF and Target MF range are currently determined.

  6. IDC Determination of Target Market FlowExample 1. 5% unconstrained > 5% constrained 0% unconstrained > 0% constrained Ex. 1 0% Constrained 150 MW 5% Constrained 30 MW 0% Unconstrained 155 MW 5% Unconstrained 45 MW Relief obligation based on 5% unconstrained (45 MW) Target MF Range – 120 to 165 MW Could cut an additional 30 MW. Could reload the 15 MW already cut. If IDC directed 5 MW cut: Target MF (Down to 0%) = Constrained MF (Down to 0%) + Reload – Relief Obligation Target MF = 150 + 15 – 5 = 160 MW

  7. Target MF Range calculated by NERC IDCExample 1. 5% unconstrained > 5% constrained Target MF = 150 + 15 – 5 = 160 MW Total Net flow NERC IDC 165 A = 15 reload Relief 5 MW Target MF Range 155 160 150 150 B = 30 120 Target MF Assigned by NERC IDC 160 MW 45 A reload 30 B Target MF Net Range Target MF 0% Unconstrained Net Market Flow 0% Constrained Net Market Flow 5% Unconstrained Forward Market Flow 5% Market Constrained Forward Flow

  8. IDC Determination of Target Market FlowExample 2. 5% unconstrained less than 5% constrained 0% unconstrained > 0% constrained When 5% unconstrained is less than 5% constrained: Ex. 2 0% Constrained 150 MW 5% Constrained 30 MW 0% Unconstrained 155 MW 5% Unconstrained 20 MW 5% Adj unconstrained 30 MW Relief obligation based on adj5% unconstrained (30 MW) Target MF Range – 120 to 150 MW (no reload) If IDC directed 5 MW cut: Target MF (Down to 0%) = Constrained MF (Down to 0%) + Reload – Relief Obligation Target MF = 150 + 0 – 5 = 145 MW

  9. Target MF Range calculated by NERC IDCExample 2. 5% unconstrained less than 5% constrained Target MF = 150 + 0 – 5 = 145 MW Total Net flow NERC IDC 155 150 Relief 5 MW 150 Target MF Range 145 B = 30 120 Target MF Assigned by NERC IDC 145 MW No reload (B >C) 30 B 20 C Target MF Range Target MF 0% Unconstrained Net Market Flow 0% Constrained Net Market Flow 5% Unconstrained Forward Market Flow 5% Market Constrained Forward Flow

  10. IDC Determination of Target Market FlowExample 3. 5% unconstrained > 5% constrained 0% unconstrained > 0% constrained When decide whether have relief obligation or a partial reload or a total reload Ex. 3 0% Constrained 150 MW 5% Constrained 30 MW 0% Unconstrained 155 MW 5% Unconstrained 45 MW Target MF Range – 120 to 165 MW Relief obligation is when Target MF is below 150 MW (120 to 150). See Ex 3a on slide 11. Partial reload is when Target MF is equal to or greater than 150 MW up to 165 MW. See Ex. 3b on slide 12. Total reload is when Target MF is at 165 MW (no relief obligation). See Ex. 3c on slide 13.

  11. Target MF Range calculated by NERC IDCExample 3a. 5% unconstrained > 5% constrained Relief obligation - Target MF is below 150 MW (120 to 150) Total Reload Target MF = 150 + 15 – 20 = 145 MW 165 Target MF Range Partial Reload A =15 reload “Relief” 20 MW 155 155 150 150 Relief Obligation 145 B = 30 120 Target MF Assigned by NERC IDC = 145 45 A = 15 reload 30 B Target MF Range Target MF 0% Unconstrained 0% Constrained 5% Unconstrained Forward 5% Constrained Forward

  12. Target MF Range calculated by NERC IDCExample 3b. 5% unconstrained > 5% constrainedPartial reload - Target MF is equal to or greater than 150 MW up to 165 MW Total Reload Target MF = 150 + 15 – 10 = 155 MW 165 Target MF Range Partial Reload “Relief” 10 MW A =15 reload 155 155 155 150 150 Relief Obligation B = 30 120 Target MF Assigned by NERC IDC = 155 45 A = 15 reload 30 B Target MF Range Target MF 0% Unconstrained 0% Constrained 5% Unconstrained Forward 5% Constrained Forward

  13. Target MF Range calculated by NERC IDCExample 3c. 5% unconstrained > 5% constrainedTotal reload – Target MF is at 165 MW (no relief obligation). Sends 9999. Total Reload Target MF = 150 + 15 – 0 = 165 MW “Relief” 0 MW 165 Target MF Range Partial Reload A =15 reload 155 155 150 150 Relief Obligation B = 30 120 Target MF Assigned by NERC IDC = 165 45 A = 15 reload 30 B Target MF Range Target MF 0% Unconstrained 0% Constrained 5% Unconstrained Forward 5% Constrained Forward

  14. Target MF Review • While the Target MF may have been correct when only a single set of MFs were reported to the IDC, problems occurred when the markets began reporting two sets of MFs to the IDC. • There are two issues, both involving the reload component of the Target MF calculation: • The reload component is equivalent to a credit for redispatch accomplished in previous hours. The current formula only takes into account redispatch provided in the forward direction by generators with impacts down to 5%. Although it is not required to use generators below 5% to meet its relief obligation, some markets may not be able to prevent generators below 5% from being used to meet its relief obligation. So in those cases where generators with impacts below 5% are used to meet the relief obligation, the market should receive credit for this to the extent other generators below the 5% threshold have not increased to completely offset the redispatch effort. This can be accomplished by making two reload calculations (one using 0% flows and one using 5% and greater flows) and using the higher of the two.

  15. Target MF Review • There are two issues, both involving the reload component of the Target MF calculation (cont): • Relief obligations can be met by either decreasing forward flows or increasing reverse flows. Since the reload component only takes the difference in forward unconstrained and forward constrained flows(see slides 16 for a description of unconstrained flows), if there is not other adjustment made, the reload component ignores redispatch accomplished by moving generators with negative response factors. This can be addressed by taking the larger of the increase in reverse flow (either down to 0% or down to 5%) and subtracting the larger increase from the forward constrained MFs and reverse constrained MFs down to 0% and down to 5%. By subtracting the same amount from both forward and reverse constrained MFs, the net stays the same and the increase in reverse flows appear in the reload component. While the three markets make some adjustments for increase in reverse flow, none make the adjustment described here that will provide full credit for redispatch in the reload component.

  16. Unconstrained Market Flow = Market Flow just before TLR level 3 or higher is called(no activation of flow gate in SPD solution) Flow gate Limit (SOL) Other impacts Other impacts NERC Tags Relief provided NERC Tags NERC IDC Market Flow Target Firm Net MF Firm Net MF Net Total unconstrained Market Flow >0% Net Total Constrained Market Flow >0% NN6 Net MF NN6 Net MF NH2 Net MF NH2 Net MF Constrained Market Flow Re-calculated every 15 minutes Unconstrained Market Flow Frozen value just before TLR issued TLR EVENT LEVEL 3 or HIGHER TLR LEVEL 3 or HIGHER

  17. Measure of Success Review • Similar to the Target MF situation, the IDC had a process in-place to determine whether the markets were successfully meeting their relief obligation prior to the field test: • The net constrained MF down to 0% last received by the IDC was compared with the Target MF at time TLR is issued for next hour (normally around 25 min. after the hour for the next hour). • If the net constrained MF down to 0% was at or below the target, this was considered a success meeting the relief obligation with no shortfall. • If the net constrained MF down to 0% was above the target, this was consider a failure to meet the relief obligation with the shortfall being the amount of net constrained MF above the target. • Under this process, failure to meet its relief obligation in one hour resulted in a sub-priority assignment in the next hour that required the shortfall be curtailed first before further cuts to tags and other market flows.

  18. How does NERC IDC measure if a Market meets its relief obligation • NERC IDC compares Net Constrained Market Flow >0% with the Net Target Market Flow and if Net Constrained Market Flow >0% is at or below the Net Target Market Flow, the Market is meeting its obligation . This option used in the assignment of sub-priorities by the IDC.

  19. Relief obligation met. Net Constrained Market Flow >0% is at or below the Net Target Market Flow Flow gate Limit (SOL) Other impacts Other impacts NERC Tags NERC IDC Market Flow Target NERC Tags Firm Net MF Firm Net MF Net Total unconstrained Market Flow >0% Net Total Constrained Market Flow >0% NN6 Net MF NN6 Net MF NH2 Net MF NH2 Net MF Constrained Market Flow Re-calculated every 15 minutes Unconstrained Market Flow Frozen value just before TLR issued TLR EVENT LEVEL 3 or HIGHER TLR LEVEL 3 or HIGHER

  20. Measure of Success Review • As part of the MF Threshold Field Test, it was decided that both impacts down to 0% and impacts 5% and greater would be evaluated for meeting the relief obligation. • This recognized that markets would likely move units below the 5% threshold to meet their relief obligation even though they are not required to do so. • A set of formulae used to establish success were developed to evaluate field test results. • The Credit for Redispatch Small Group still needs to evaluate these formulae to make sure they consistently demonstrate success. • These formulae were only used for the MF Threshold Field Test and are not used to set the subpriority relief obligation. • The Credit for Redispatch Small Group will decide whether setting subpriority relief obligations should continue using net constrained MF down to 0% compared to Target MF or whether it should use the formulae from the field test.

  21. Credit for Redispatch ScenariosCurrent Calculations Questions?

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