Balancing Swings in Power from Wind Farms on the Bonneville Power Administration Grid

Michael Giberson

From the Yakima Herald-Republic, “Ebb and flow of wind power stress NW power grid,” a report of the challenges in keeping the Bonneville Power Administration (BPA) transmission grid balanced when power output from wind farms varies quickly:

In the space of one hour last month, electricity generated at wind farms in the eastern end of the Columbia River Gorge shot up by 1,000 megawatts – enough to power some 680,000 homes.

Less than an hour later, it plummeted almost as much.

Sitting in front of 10 computer screens in a fifth-floor room of the federal Bonneville Power Administration headquarters in Portland, Kim Randolph had to react quickly.

Working from a keyboard, she diverted millions of gallons of water away from massive turbines spinning in Columbia River dams and sent it around the dams.

The 17-year veteran power operations specialist remembers how fast she needed to work as a wind storm caused generation to peak and fall three times over eight hours.

“You have to get it in hand and get it in hand very quickly,” she said.

Getting it in hand is a balancing act. It means balancing the power generated by 31 dams, a nuclear power plant and now wind farms in order to send a stable flow of power into the BPA’s 15,238-mile grid across the Pacific Northwest.

It also means balancing the grid’s needs against those of fish and commercial river traffic on the Columbia River.

Getting power from wind, which can vary greatly, is complicating that balancing act.

The article provides some background on wind power development in the Pacific Northwest and the difficulties the BPA is having managing some of the more extreme variations in output.  One of the points made later in the article is that independent (non utility) power generators in the area have long felt that BPA needed to update its transmission grid and interconnection rules.  The relatively rapid development of wind power has helped push BPA to work a little harder on these issues.

But the thing that really struck me when reading the article was the manual intervention to keep the system in balance.  Given the complicated balancing act – varying wind power, varying consumer load, and hydro power availability limited by current fish and commercial river traffic – wouldn’t it make more sense to have these things automated? (Likely they do for operations within some range, but maybe the automation can’t handle more extreme variations.)

Another issue raised late in the article concerns a controversial three-strikes-you’re-out rule to be implemented this fall for wind generators that don’t respond to requests for curtailment from BPA, and a related proposal to allow wind power generators to pay fossil-fueled power plants to curtail in place of a wind power farm.  A less cumbersome and more transparent approach is available in regions with independently-operated energy balancing markets, which provides an economical way to identify which units to curtail when supply and demand threaten to move out of balance.

RELATED: A BPA press release from July 21, 2009, said the agency proposes to increase rates for energy customers by 7 percent on average.  Also, “BPA’s relatively new rate for wind integration services has been reduced substantially from the initial proposal due primarily to efforts from the wind power industry to improve their operational practices.”

Also, a “BPA and wind power” story from The Oregonian, with more emphasis on BPA’s proposed rate increases for wind power generators and other details on rule changes. The Oregonian article suggests that the wind integration rates were reduced (from a nearly 300 percent increase to a mere 90 percent increase) largely due to a “firestorm of criticism.”

More information on BPA and wind power (from BPA).