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What Happened in ERCOT

Voltage sag shows value of accurate wind forecasting.

Fortnightly Magazine - May 2008

on February 26, but as it happened, ERCOT possessed data that accurately predicted the decline it saw in wind generation  (see Figure 2) . Its system planners weren’t using that data, however, because the AWS TrueWind forecasting system was being tested for application only to the nodal market ERCOT is developing for Texas.

“When we go into our new nodal system at the end of the year, we won’t be relying on the generators for wind forecast data,” Saathoff says. “We’ll do the forecast, and our test system did pretty well tracking the wind.”

Similar systems are being tested and deployed in other regions that expect significant growth in wind generation. Xcel Energy, for example, is testing a WindLogics system to help it more accurately predict wind generation in its Northern States Power territory  (see “Taming the Wind,” p. 60, Fortnightly, February 2008) . And in early April the New York Independent System Operator (NYISO) contracted with AWS TrueWind to provide a centralized forecasting system for the NYISO grid.

NYISO proposes to require wind generators to finance the costs of forecasting, and also to penalize wind generators who repeatedly fail to provide required meteorological data. In return, it would increase the amount of wind generation eligible for exemption from under-generation penalties and full compensation for over-generation.

“As more windpower projects are connected to the grid, they will require enhanced attention,” said Robert Hiney, NYISO interim president, in a statement. “The advance forecasts will allow us to accommodate windpower more accurately and reliably.” NYISO now draws power from less than 500 MW of wind generating capacity, but nearly 7,000 MW of proposed wind projects are moving through the grid-interconnection process.

Similar quantities of new windpower capacity are being developed in Texas, adding to its existing 4,400 MW of windpower capacity. “We need to try to get that wind forecast into our current zonal operating system,” Saathoff says, “so we’ll have a better representation of what the wind generation is going to do and we can commit in advance any other units that might be needed.”– MTB