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Declaring Emergencies in California: The Realities of ISO Operation

An independent system operator's view on the energy crisis and the realities of maintaining reliability.
Fortnightly Magazine - October 15 2001

2001. Page 10 lists the interruptible and firm load curtailments for the example dates.

Learning From The Crisis

There exists many complex and ever changing conditions on the supply, demand and the transportation system (transmission) that the system operators must consider in managing the electric grid in real-time. It is easy for many to "second guess" the operators' action. The operators are well trained to perform their duties under ever-stressful conditions. They must make real-time decisions in accordance with CAISO, regional and national reliability requirements in a very short amount of time with limited information. The California crisis has brought much needed publicity and attention to many important electric energy industry issues that have been ignored for decades. Furthermore, it is clear that many measures are needed to efficiently run the system and maintain reliability. Some of these measures are the articulation of a clearly defined role for the CAISO, increased regional coordination, enhanced internal coordination between the CAISO and Municipal districts, UDC's and generator owners, to name a few.

  1. Stage 3 Emergency Notice is declared by the ISO any time it is clear that an Operating Reserve shortfall (less than 1-1/2 percent) is unavoidable or when in real-time operations, the Operating Reserve is forecast to be less than 1-1/2 percent after dispatching all resources available.
  2. The formal "ISO Alerts, Warnings, and Emergencies" procedures as well as related tariff and dispatch protocol sections are posted on its website at
  3. The CAISO control area geographically includes most, but not all of California. While the previous control areas of Pacific Gas and Electric, Southern California Edison, and San Diego Gas and Electric are part of the CAISO control area, municipal utilities such as the Los Angeles Department of Water and Power (LDWP), Imperial Irrigation District (IID) and others have their own control areas for which their generating resources in California are not included as CAISO internal resources.
  4. Even if qualifying resources (QFs) are running at full nameplate capacity, only a fraction of this capacity may be available to meet system loads. Only "surplus" output after that which is directly used to meet the owner/host's native load may be viewed as "available" to meet CAISO system loads. The CAISO is currently working with the utilities to determine the amount of native load associated with each QF to accurately assess the net generation capacity available from these resources to support the grid.
  5. The operations of Northern California QFs have been cycled off and on daily in accordance with the terms of their power purchase agreements. These QFs do not typically ramp to full output until noon each day or shortly thereafter. While not at full output, Path 15 mitigation is sub-optimal and overloads are more difficult to manage. If these Northern California QF resources were base loaded around the clock, QFs could assist in mitigating Path 15 overloads.
  6. The UDCs include Pacific Gas and Electric, Southern California Edison, and San Diego Gas and Electric.
  7. "Path 15 Reliability Upgrade Analysis", CAISO Operations, Page 1.
  8. While emission-limited facilities have contributed to unplanned outages recently, cooperative measures