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Plunging Wind Into the Grid

The California ISO's intermittent resource program addresses a key market barrier to wind power: how to schedule wind energy in forward markets.
Fortnightly Magazine - June 15 2003

power. Lastly, voltage collapse within wind project areas due to shifts in power generation among fleets of wind turbines and transmission constraints can reduce available energy sales.

This long list of challenges is daunting. However, AWEA's Caldwell, and Jan Smutny-Jones, executive director of the Independent Energy Producers, helped pull together stakeholders to huddle with California ISO staff and see if a system could be devised that would better serve everyone, including the wind industry and state ratepayers. Members of IEP, AWEA, California Wind Energy Association, wind energy marketers, and a new trade group consisting of smaller wind project operators concerned mostly about maintaining the viability of existing wind farms were all brought into the same room with regulators. Representatives of the governor's office, California Energy Commission (CEC), and the California ISO also attended.

Consensus Process Leads to Innovative Solutions

The Intermittent Resources Working Group convened during the summer of 2001, the height of California's energy crisis. The end result was the Participating Intermittent Resources Program, which allows wind developers to reduce uncertainty regarding settlement of schedule deviations while upgrading forecasting techniques to take advantage of new information technologies that provide better information on wind energy output for grid operators at the California ISO.

The new approach is based on a more sophisticated forecasting service that uses state-of-the art methods and real-time data to develop the hourly forecasts of wind energy production. The two-hour-ahead forecast then serves as the schedule for grid operators. The basic premise underlying this new approach is the ability to predict wind generation in real time, to keep the system balanced. Each individual wind project participating in the ISO's program is required to install meters, share in the costs of forecasting, and schedule energy deliveries based on these state-of-the-art predictions of energy production.

As data is collected over time for each wind project, the accuracy of the energy production forecasts should continuously improve. The ability of the California ISO grid operators to balance load with generation only will get better as the forecasts improve for the existing and new wind projects serving the California power market.

Computer innovations already have begun to address challenges linked to wind's intermittency and problems of utility integration. A recent study performed by Southern California Edison showed a new wind forecasting system could have saved the utility $2 million in the month of December 2000 by better forecasting the day-ahead performance of 1,000 MW of wind power capacity delivered to its distribution system. The rate of previous forecasting error was reduced by as much as 50 percent with this new forecasting technique.

With the Participating Intermittent Resources Program, far greater savings can be achieved. As the forecasting database grows over time, the deviations between scheduled and delivered energy will shrink. The forecasting tool must produce an unbiased forecast for each and every hour.

On the financial side of the equation, intermittent wind resources participating in the program are exempt from deviation replacement reserve penalties. Instead, replacement reserves, as well as imbalance costs, are treated like changes in loads instead of generation. This technical change