Control of a permanent magnet synchronous generator used in a variable speed wind energy system

To obtain maximum power from a stall controlled wind energy converter (WEC) it has to be operated in the variable speed mode. With the generator connected to the grid via a self-commutated converter with intermediate voltage circuit, the generator speed and hence the speed of the wind turbine can be controlled by the generator side inverter. In a preferred control concept the generator is operated at its optimal working point in order to minimize the losses in the generator and the power electronic devices. The paper considers a synchronous generator with permanent magnet excitation. Such machines have been employed with several 100 kW and are under consideration in the MW range.