Pitch system failure caused Vestas turbine collapse at Irish wind farm

What happened

A Vestas V52-850kW turbine at the Loughderryduff wind farm in County Donegal, Ireland, collapsed in March 2013 during high winds. An investigation by Vestas found that an error in the turbine's pitch system meant at least one blade failed to pitch out of the wind, causing an over-speed condition. The over-speeding blade struck the tower, causing structural damage that led to the turbine's collapse. Debris from the collapse reportedly scattered over a large area, raising local safety concerns.

The eight-turbine site was closed for five days following the incident before being reopened after an inspection by the operator, North West Wind. Vestas released details of the cause seven months after the event, prompting criticism from local residents and a county councillor over the delay and the refusal to publish the full technical report.

Contributing factors

A malfunction in the turbine's pitch control system meant a blade did not pitch out of the wind as required, leading to an over-speed event in which the blade struck the tower and caused structural failure.

Lessons learned

1. A pitch system fault on a Vestas V52 turbine allowed blade over-speed that struck the tower, so operators should test pitch fault detection and automatic shutdown logic at regular intervals.
2. Debris from a collapsed onshore turbine scattered over a large area, so operators must map realistic debris exclusion zones after any tower or blade failure.

More lessons on structural integrity and turbines, from every incident on the register.

Not yet known

• Full technical report from Vestas
• Turbine age at time of failure
• Cost of the collapse and repairs

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Source

Windpower Monthly (windpowermonthly.com)