Public Utilities Reports

PUR Guide 2012 Fully Updated Version

Available NOW!
PUR Guide

This comprehensive self-study certification course is designed to teach the novice or pro everything they need to understand and succeed in every phase of the public utilities business.

Order Now

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

withheld or otherwise manipulated to create an artificial shortage (this article does not intend to offer complete treatment to artificial shortage or market manipulation). Rather, lets examine the total supply availability and compare it to the demand. "Installed or nameplate capacity" is the maximum capability of every generating unit in absolute perfect conditions. "Available or dependable capacity" is a subset of the installed or nameplate capacity actually capable of generating at any given time. The actual availability of generation, also referred to as dependable capacity, on any given day is generally less than the nameplate for several reasons:

  • Hydro resource availability is dependent on water levels, stream flow, irrigation and environmental requirements, water storage capacity, precipitation and snow pack in a given year.
  • Over 64 percent of the fossil supply fleet in the ISO area is over 30 years old and requires frequent maintenance combined with a higher rate of break-downs or forced outages.
  • Typical generator availability is between 70 to 90 percent. This means that a generating unit is only available 70 to 90 percent of the time.
  • Intermittent resources (i.e. wind and solar) are only available when conditions permit. For some of these resources availability of this type of generation can be less than 20 percent of installed capacity.
  • Qualifying Facility installed capacity may not all-available to supply demand across the state since significant amounts of its capacity supply "on-site" load within the premises of the qualifying facilities.
  • Other realities that could limit the availability of supply include transmission limitation, gas supply, and environmental restrictions.

Emergency Notifications: How it Works

The CAISO uses emergency notifications 2 to communicate system conditions that threaten electric system reliability. This includes such dangers as CAISO grid instability, voltage collapse or under-frequency caused from transmission or generation trouble-conditions which could also impact the Western Systems Coordinating Council (WSCC) grid. It is important to realize that Emergency Notices are not only declared when an emergency condition exists, but are also used to help prevent an uncontrollable system emergency before it occurs. For example, stage emergencies may be declared at any time it is clear that an operating reserve shortfall is unavoidable or is forecast to occur within the next two hours. In its process of determining whether or not to declare emergencies, the CAISO assesses different factors on a day-ahead, hour-ahead, and minute-by-minute basis. It looks for times when actual demand exceeds forecasts, when the hour-ahead market is short on scheduled energy and ancillary services, and most importantly, when operating reserves do not satisfy WSCC operating reserve criteria.

Consequences of the Shortages: Day-to-Day Realities

California is facing an electricity shortage of unprecedented proportions coupled with a market that is not workably competitive. The consequences have been serious, and the realities that regularly confront the CAISO operators are complex at best. The CAISO strives to keep supply and demand in equilibrium and endeavors to avoid the shedding of load until it becomes inevitable. The CAISO only declares emergencies when it is absolutely necessary to do so if a system emergency is to be averted. Accusations that the