Demand-Response, Spinning-Reserve—A New Tool to Reduce the Likelihood of Outages

By Consulting Specifying Engineer Staff August 22, 2006

The first-ever demand-response, spinning-reserve demonstration will give California a new tool to avoid rolling blackouts during periods of high electricity demand. The joint project of the Consortium for Electric Reliability Technologies (CERTS) and Southern California Edison (SCE) will begin in August.

The work is funded by the California Energy Commission’s Public Interest Energy Research Program and is being carried out in cooperation with the California Independent System Operator (CAISO), which operates the state’s electricity grid.

“Spinning reserve” refers to electricity generating plants that are standing by to provide additional electricity to the grid on a moment’s notice.lling blackouts,” explains Jim Detmers of CAISO.

“Demand response” (DR) strategies reduce non-essential consumption of electricity by customers when demand is high on the grid and the possibility of rolling blackouts or system failure is imminent. Technologies and strategiesfor automated demand response are areas of active research, and the state of California is looking to DR to improve the reliability of its grid by reducing peak power consumption and the risk of rolling blackouts.

Electric utilities have developed a variety of demand-response programs to which large and small customers can subscribe. In return for their commitment to reduce nonessential demand–for example, turning off lights and reducing air conditioner use–during times of high demand on the grid, customers receive price breaks and other benefits from their utility.  

The project will demonstrate how the electrical grid operator can use demand-response programs as a tool to increase grid reliability and avoid blackouts.  Customers in a specially metered geographic region of SCE’s air conditioner load-cycling program, called the Summer Discount Program, may join voluntarily.During the demonstration, SCE will call on participating customers to curtail their energy use at pre-scheduled times during summer weekday afternoons for periods of five to 20 minutes each between 2 p.m. and 6 p.m.

According to John Kueck, lead CERTS researcher at Oak Ridge National Laboratory,“Demand response in the form of traditional utility load management programs has been around for some time. However, until now, no one has demonstrated the use of aggregated demand response to provide spinning reserve.”

California ISO staff and other participants will observe load curtailments on a secure, external website that can read and broadcast the specially metered data in real time. CERTS researchers will also install high-resolution, real-time data monitoring devices to record loads (and indoor temperatures) from a statistical sample of individual air-conditioning cycling units for further analysis of the AC usage patterns and the effectiveness of the pre-scheduled interruptions.

Janine Nelson-Hoffman, project manager for SCE’s circuit saver project and demand-response, spinning reserve pilot, says “Provision of spinning reserves with demand response is another way by which SCE is exploring how its long-standing load management assets can be modernized and improve reliability for customers.”

The California ISO, the state’s investor-owned utilities, and the Western Electric Coordinating Council will analyze the results to assess the impact on the reliability of the electricity grid and explore options for extending the use of demand response throughout California’s grid.

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