Damping control for Permanent Magnet Synchronous Generators and its application in a multi-turbine system

Permanent Magnet Synchronous Generator (PMSG) offers higher efficiency than induction and wound-field generators. This higher efficiency, however, manifests itself as a lack of natural damping. When connected to an AC voltage source, a small, sustained sub-synchronous oscillation is often observed. In this paper, we present a method for damping such undesirable oscillation without the need for a full power inverter, as required for implementing a field-oriented control algorithm. The power rating of proposed damping controller is only a small fraction of the power of the PMSG. The proposed damping controller can be used for grid-tied applications or in conjunction with a variable frequency converter, for variable speed operations. We demonstrate the application of the proposed damping controller in a wind turbine system that consists of multiple turbines using PMSGs and one shared converter. We also propose a method for peak power tracking for this multiple wind turbine configuration.