Characterization Study of a Grid Connected DFIG Based WECS Under Variable Wind Speed and Loading Conditions

Abstract

Grid-connected doubly-fed induction generator (DFIG) based wind energy conversion system (WECS) is widely used in harnessing wind power. The paper attempts to characterize a 15-kW grid-connected DFIG based WECS operating under variable speed and loading conditions. Back to back converter topologies are utilized consisting of rotor side converter (RSC) and grid side converter (GSC) controlled in the synchronous reference frame coordinates. The design, modeling, and control of various system components are deliberated. The interaction of the grid with the proposed DFIG-WECS is analyzed where the regulation of the machine active power is achieved through the control of RSC. The current quality, voltage regulation is achieved by the control of GSC. Case studies involving constant wind speed, variable wind speed, and variable loading are undertaken for the characterization analysis. The performance characterizations of the entire system is validated in Matlab/Simulink simulation environment where the critical performance parameters like DC link voltage, generator torque, DFIG stator current, active and reactive power delivered by the DFIG to the grid, PCC side voltage/ current profile and the PCC current Total harmonic distortion (THD) are rigorously monitored, presented and discussed for each case studies.