Linear parameter-varying control of permanent magnet synchronous generators for wind power systems

This study presents an optimal control strategy for the electronic interface of a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). A linear optimal control is used on the grid side of the interface to ensure a proper power transfer and a linear parameter-varying (LPV) control on the machine side to cope with the wide operating conditions demanded by the wind turbine applications. The dynamics of a PMSG working in a variable speed wind turbine is affected by the rotational speed of the wind rotor. The LPV control uses the generator speed as a scheduling variable to adapt itself to different operating conditions. The proposed scheme results in a multi-variable self-scheduled controller with a PI structure similar to classical approaches. Thus, the control ensures performance and stability in all possible operating conditions whereas the implementation and the numerical stability are similar to previous schemes. The proposed control has been implemented in a test bench that includes a fully-rated back-to-back converter. The experimental results show a good performance in different scenarios in which the controller has to adapt itself to highly varying operating conditions.