Grid interface options for variable-speed, permanent-magnet generators

The authors survey the many forms of DC/AC power converter which may be applied to permanent magnet generators, examine their potential to meet the waveform, power factor, cost and efficiency requirements and consider their features in relation to the special environment of a wind turbine system. Feasible options are identified and compared. The control needed to achieve maximum energy capture from the wind is described. Inverters have been selected which are able to effect the necessary power control whilst providing controllable reactive power and causing minimal harmonic pollution of the network. Device cost and overall efficiency have been assessed for each option