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Wind farm has precautions against ice throws

Even when it comes to the giant blades of the turbines in Amaranth and Melancthon, there might be truth in the old expression that "it's an ill wind that blows no good." This might have been the case when the Melancthon I wind project had to be shut down for nine days in December 2006 because of an ice storm and the resultant imbalance of the blades.

Even when it comes to the giant blades of the turbines in Amaranth and Melancthon, there might be truth in the old expression that "it's an ill wind that blows no good."

This might have been the case when the Melancthon I wind project had to be shut down for nine days in December 2006 because of an ice storm and the resultant imbalance of the blades.

The phenomenon of ice there led to concerns about the possibility of ice throws from the rotating blades, and then to agreements on ice protocols in the interests of safety.

It was also a learning experience for Mike Jablonisky and the rest of the Canadian Hydro Developers crew at the site. And it also led to computerized innovations at the turbines.

Even prior to the ice storm, the turbines would automatically shut down when the buildup of ice came close to a critical point. In the two years following the storm, the computerized system that shuts them down has been enhanced.

"Now we have software within the turbine that detects the slightest change in ratio of torque to wind speed and the turbines shut themselves down automatically. This software works incredibly well," said Mr. Jablonisky.

"All that said, the way to beat ice build up is... more [truncated due to possible copyright]  

Even when it comes to the giant blades of the turbines in Amaranth and Melancthon, there might be truth in the old expression that "it's an ill wind that blows no good."

This might have been the case when the Melancthon I wind project had to be shut down for nine days in December 2006 because of an ice storm and the resultant imbalance of the blades.

The phenomenon of ice there led to concerns about the possibility of ice throws from the rotating blades, and then to agreements on ice protocols in the interests of safety.

It was also a learning experience for Mike Jablonisky and the rest of the Canadian Hydro Developers crew at the site. And it also led to computerized innovations at the turbines.

Even prior to the ice storm, the turbines would automatically shut down when the buildup of ice came close to a critical point. In the two years following the storm, the computerized system that shuts them down has been enhanced.

"Now we have software within the turbine that detects the slightest change in ratio of torque to wind speed and the turbines shut themselves down automatically. This software works incredibly well," said Mr. Jablonisky.

"All that said, the way to beat ice build up is to not let it happen at all.

"When we have a local forecast stating freezing rain for a certain time period (usually in the offhours of operation), we would monitor the facility for any variation of the turbine power curve (curve that shows the relation of wind speed to power output of a turbine). When we see a variation starting, we know that this is the start of an icing event.

"Protocol is to shut down the entire facility until the freezing rain has stopped," he said.

When the ice on the turbines built up two years ago, the Melancthon crew "would yaw the turbines so the blades were facing into sun, every day, all day.

"We would do this until the blades were clear of all ice. After the eighth day, we brought one turbine on line and the power curve reflected the exact performance that the turbine was expected to do," he said.

"We brought the rest of the facility on line one turbine at a time to ensure we didn't have any ice that may have not been detected.

"We were all good, so by the end of that Sunday, almost nine days later, we were back online."

According to a Swiss study in climatic conditions similar to those of Dufferin, ice throws ranging from 50 to 100 metres from the base of the turbine are possible under certain conditions. The study found nothing beyond 100 metres.

Despite all precautions, CHD in November issued an advisory warning that ice build-up is possible. The advisory outlined the basic protocol in such an event, and said that following a shutdown the staff would ensure that the area around a turbine would be clear of people before starting the blades up again.


Source: http://www.citizen.on.ca/ne...

MAR 4 2009
http://www.windaction.org/posts/19354-wind-farm-has-precautions-against-ice-throws
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