Performance of PMSG Based Variable Speed WECS with Parallel Back-to-Back Converters Using Separate Zero d-axis Current Control

Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) is highly preferred these days with back-to-back converter topologies. In order to overcome the sudden converter failure problems, to reduce DC-link rating and for continuity of power supply to the grid; this paper proposes variable speed WECS using PMSG with parallel back-to-back converters with separate DC-links. In both the converter strings the generator-side converters are controlled by using separate Zero Direct-axis Current (ZDC) control with Optimal Torque Control (OTC) technique for Maximum Power Point Tracking (MPPT) and both the grid-side converters are controlled with the help of separate grid-side control. In addition, the problem of zero sequence circulating current has been taken into account. The proposed scheme is been implemented using the MATLAB environment and the overall performance of the system is evaluated through experimental studies.