Modelling and control strategy of PMSG based variable speed wind energy conversion system

With the advance of power electronic technology, novel control strategies and new circuit topologies direct driven permanent magnet synchronous generators (PMSG) have increasingly drawn interests to wind turbine manufactures. In the proposed wind energy system, a PMSG is used as a variable speed generator. The generator model is established in the synchronous-rotating dq reference frame. The torque of PMSG is suitably controlled according to a generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control without a wind speed detector. The speed control is realized through field orientation where the q-axis current is used to control the rotational speed of the generator according to the variation of wind speed and the d-axis current is set to zero. Active and reactive power can be controlled by direct and quadrature current components, respectively.