A critical property of an offshore wind turbine is its reliability. The concept presented here aims to improve turbine reliability via the use of a permanent magnet induction machine. This allows the gearbox and converter to be abandoned, thereby reducing the total number of parts. To adapt the rotation speed to the wind speed, a new control concept with just one central converter is used to control the frequency of the park grid. At partial load a maximum power point control is applied to find the optimal frequency. Active stall and pitch control have been investigated at rated load.

By Eckehard Tröster, Technische Universität Darmstadt, Germany