Wind ‘Ramp Events’ Get California’s Attention

Wind’s variability as a power source always makes it a little tricky to integrate into the grid, but what really sends shivers down the spines of operators are “ramp events” – dramatic changes in wind plant power output in a short period of time caused by big shifts in wind speed. In California, there’s a new effort getting under way to improve the forecasting of ramp events, with the state’s Energy Commission awarding a $398,662 grant to researchers at the University of California, Davis.

The commission said the grant will help researchers develop and implement “a tool that gives the California Independent System Operator (CAISO) advance warning of wind ramp events.”  This is especially pressing as California moves to bring vast new wind capacity online with huge developments like the Alta Wind Energy Center in the Tehachapi Mountains. The commission said the UC Davis project would focus on that area, as well as the San Gorgonio wind resource area in Southern California and the Altamont Pass and Solano County wind areas in Northern California.

wind forecasting, Davis study

image via Shutterstock

The commission said the Davis researchers would study historic wind data in those regions to perfect a tool that would allow for forecasts that, for example, might tell operators there was an 80 percent chance that a front with winds gusting up to 50 mph would pass through a wind power area within a 45-minute timeframe. “Grid operators could use such information to help decide what actions are needed to ramp up or down the generation system,” the commission said.

Ramp events can work in either direction, with a sudden loss of wind also putting plant and grid operators in a bind. A 2010 Argonne National Laboratory study [PDF] of wind ramp forecasting outlined typical responses under each scenario.

“To deal with a ramp-up event, a wind power producer can shut down turbines to avoid producing an excess of energy that cannot be compensated for by a sudden decrease in thermal generation, or it can increase its generation in agreement with the system operator and utilities,” the researchers wrote. “In the latter case, utilities can trade fossil energy costs by buying cheaper and clean wind energy. In a ramp-down event, the system operator can switch on fast hydro units or, if this procedure does not  generate enough power to meet demand or is not available, the operator can use fossil energy turbines to meet the load. If these measures are not sufficient, load curtailment must be adopted – a scenario that system operators obviously try to avoid.”

Earlier this year, the U.S. Department of Energy, in partnership with the National Oceanic and Atmospheric Administration (NOAA) and industry players, launched the Wind Forecast Improvement Project. Researchers are gathering data for a full year with a network of sophisticated instruments taking measurements of atmospheric conditions in the upper Midwest and Texas. Once the data is gathered, NOAA plans to incorporate it into an advanced weather forecasting model to provide more accurate forecasts for wind speeds and directions at the typical turbine height of 300 to 400 feet above ground.

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Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.