How to keep a power grid stable? Flywheels in O.C.May 29 - McClatchy-Tribune Regional News - Pat Brennan The Orange County Register
Orange County's beachside power plant is in the midst of a major redesign to help prevent summertime outages -- the second time that AES Huntington Beach, known for its towering exhaust stacks, has reinvented itself to plug potential power gaps if the San Onofre nuclear plant remains offline. But this year's project is a radical departure from the plant's traditional mission to generate electricity. Instead, two former natural-gas-fired power units, pulled back from retirement last year to help with high summer power-demand, are being converted into something completely different. In a word, flywheels. The free-spinning wheels generate no electricity of their own. But they could prove critical when millions of air conditioners chug to life to combat summer heat. The flywheels, known as synchronous condensers, will help keep the power grid stable. In times of high demand, and without a steady flow of power from San Onofre, the grid can experience sudden dips or surges in power. The flywheels release or absorb power to smooth these fluctuations. And electricity in the Southern California grid stays steady, reducing the risk of brown-outs or blackouts. "Without San Onofre, the voltage is more prone to sag," said Weikko Wirta, plant manager at AES Huntington Beach. The Independent Systems Operator, manager of the state's power grid, considers AES's conversion one of the most important measures to guard against possible outages, said spokeswoman Stephanie McCorkle. Transmission system upgrades also have been made, she said. But the agency still will likely call for conservation by consumers during periods of high power demand. "San Onofre provided a tremendous amount of voltage support for that area of the grid, which is somewhat deficient in transmission," she said. Even with the help from AES, the area "is still going to be at risk." But the risk of power disruptions should be greatly lessened by the conversion of the AES plant. Wirta gave visitors a tour last week of the construction site on a broad deck atop the gargantuan power plant. "It's a combination project," Wirta said. "New equipment and new technology, and the existing plant and systems." That brings with it plenty of problems for engineers. "Any time you retrofit something, marry new equipment to old equipment, there are technical challenges," he said. Plant workers and contractors were busy putting the finishing touches on the project, connecting the two pairs of flywheels to their "pony motors," one for each pair, and plugging spaghetti-like clusters of wires into the plant's control room. In their previous life, the flywheels, or generators, were attached to steam-driven turbines to produce electricity. They made up the plant's power units 3 and 4. Now they've been separated from their turbines, which sit idle, returning to a retirement that was planned as part of an air-pollution-control measure arranged with the South Coast Air Quality Management District. The power units' retirement -- itself a major engineering job -- had already begun, the units already disabled, when AES was called upon to restore them temporarily to life as summer 2012 approached. When running, the San Onofre nuclear plant can produce 2,200 megawatts of electricity, roughly 19 percent of the power Edison supplies to Southern California. But both of San Onofre's reactors have been offline since January 2012. The nuclear plant's Unit 2 reactor had been shut down for routine maintenance earlier in the month when a small release of radioactive gas prompted the shutdown of Unit 3 onof that year. Inspections revealed unexpected wear among thousands of metal tubes inside the nuclear plant's four steam generators, two for each reactor unit. The wear was traced to design flaws in the generators, and the plant's operator, Southern California Edison, began a complex effort with help from a variety of consultants to track down the cause of the problem. Edison has requested permission from the Nuclear Regulatory Commission to restart its Unit 2 reactor at 70 percent power, which the utility company says should curb the vibrations believed to have caused the unexpected wear. The plan must clear a variety of regulatory hurdles, however, and has encountered fierce opposition from activist groups. Whether Edison's request will be granted, and when, is unknown. Like last year, the uncertainty prompted the California Independent Systems Operator to prepare contingency measures if the nuclear plant remains offline. And, again like last year, one of the most important measures involved AES Huntington Beach. "We got a call from ISO to see if we would consider doing it," Wirta said. "The people at AES Huntington Beach are used to rising to the challenge." He said he expects to meet a June 4 deadline to complete the retrofit. "This project is critical to grid stability this summer," he said. Contact the writer: 714-796-7865 or pbrennan@ocregister.com. http://www.energycentral.com/functional/news/news_detail.cfm?did=28774649 |