Deployed Supplemental Reserves (MW)
Share of Cleared MW Called for Deployment
Figure 36: Non-Responsive Supplemental Reserve Deployments 2009
MW Deployed But Not Responding in 30 minutes
Deployed MW Responding in 30 min
Deployed MW Responding in 10 min
Share of Called MW not Responding
2009 State of the Market Report
prices. We recommend that the Midwest ISO discontinue its relaxation practice and set prices based on the penalty price during shortages.
The Midwest ISO began directly deploying supplemental reserves during Disturbance Control Standard (“DCS”) and ARS events in 2009. There were nine such deployments in 2009. Figure 36 shows the response of the supplemental reserves deployed, separately indicating those that were successfully deployed within 10 minutes (as required) and within 30 minutes.
Jan 17 Mar 23
Sep 12 Sep 26
The response of units deployed for supplemental reserves was poor in 2009. Only 39 percent of reserves were successfully deployed within 10 minutes during the nine events, and an additional 32 percent were deployed within 30 minutes. Hence, almost 30 percent of the reserves did not respond within 30 minutes – this share was even higher during the events that required the largest deployments. Poor performance can significantly degrade reliability and raises concerns that suppliers may be selling reserves that they are knowingly incapable of deploying.
In response to this poor deployment performance, the Midwest ISO has proposed Tariff changes to add additional testing and verification requirements for offline supplemental reserves.