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Litany of design failures

Operating the Kenetech KVS 33 wind turbine was likened to "life in a high maintenance environment" by Bill Barnes of LG&E Power Inc, speaking at the American Wind Energy Association's annual conference in Austin, Texas, in June. LG&E is the largest owner and operator of the KVS 33M model, said Barnes.

He told delegates about the series of problems LG&E has had with keeping its nearly 400 KVS 33 turbines on line in Texas, California and Minnesota. These include failures of the pitch angle associated with the turbines' variable pitch control system; failures of the hydraulic pump yaw controls; and failures with the power electronics system. Nonetheless, the machines have produced significant amounts of clean electricity for consumers, even while suffering extremes of weather in all three states.

Barnes blamed tower cracks on multi-directional winds in Palm Springs, where sudden shifts in wind speed have caused blade problems and "yaw outs." Machines in Texas have suffered stress from lightning strikes and sudden vertical winds that sweep up a 35 metre rise in the land, he said. Dry climates in Palm Springs with temperatures reaching up to 52 degrees Centigrade can damage the power supply; seals in the down tower have also cracked during rainstorms, allowing water to leak in. Winter temperatures in Minnesota, which can plunge to -57 degrees Centigrade, "can keep turbines off line for several hours in the morning for as long as two weeks," Barnes said.

Below expectations

Conference participants also learned that the 5 MW project of 112 KVS 33 turbines run by the Lower Colorado River Authority (LCRA) have performed below expectations. LCRA, whose power purchase arrangement stipulated payment only upon power production, has not suffered financially. "There is a definite advantage to not owning the plant," acknowledged LCRA's Tom Foreman. Despite all the technical glitches, the cost of wind generated electricity had added no more than $0.18 a month to the electricity bills of LCRA customers.

Foreman said the wind farm held up rather well in 1996 despite Kenetech's bankruptcy and a late storm that battered the region with winds exceeding 71 m/s. Four turbine towers buckled and 22 blades cracked. "Our engineers told me a conventional coal or gas plant might have been out of service for an entire year" after experiencing the same type of abuse from the wind, Foreman said.

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