Steady State Performance of Grid Connected PMSG Wind-Turbine Using New ZDC Control Under Asymmetrical Voltage Sags

Abstract

Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) is highly preferred these days with back-to-back converter topologies. The operation and control of a grid-connected wind turbine with a PMSG have been investigated under asymmetrical grid side voltage sags. To deal with such conditions, a fast-acting control scheme is needed. It is shown in this project new Zero-Direct Axis (ZDC) control can meet the challenge. In the proposed control scheme, first the active/reactive powers and DC link voltage are decoupled, so that the asymmetrical grid side voltage sag problems can be able to dealt with proposed control scheme independently. To minimize voltage stress inflicted by the grid side asymmetrical voltage sag on the power electronic converters, a feed-forward negative sequence voltage is used in the vector current control strategy. In both the converter (GSC converter and MSC converter) strings the generator-side converters are controlled by using separate 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. The effectiveness of the proposed control scheme has been validated by extensive MATLAB simulations platform.