Maximum-Power-Extraction Algorithm for Grid-Connected PMSG Wind Generation System

This study proposed a maximum-power-extraction algorithm (MPEA) including a maximum-power error driven (MPED) mechanism and a maximum-power differential speed (MPDS) control for a grid-connected wind generation system with a permanent-magnet synchronous generator (PMSG). The MPED mechanism works as the maximum-power-point-tracking (MPPT) method in the photovoltaic system gradually increasing to its maximum value by regulating the direction of grid-connected current command according to the power variation trend. Moreover, the MPDS control produces an additional step of current command based on the instantaneous difference of generator speeds so that it can prevent the wind turbine from stalling at the suddenly dropping wind speed and achieve the object of maximum power extraction instantly as a stiff wind flowing through the wind turbine. In addition, the output is connected to a utility grid for providing energy flexibility via a unipolar full-bridge inverter controlled by a digital-signal-processor. The grid-connected experimentations of the proposed MPEA scheme without any mechanical sensors for a wind-power emulation system via a PMSG driven by an induction motor are given to examine its feasibility in practice