Dual-PI Rotor Current Control of Doubly-Fed Induction Wind Generators under Unbalanced Grid Voltage

This paper studied mathematical model of doubly-fed induction generator (DFIG) based wind turbine generation system under unbalanced voltage. A dual-PI current control strategy was proposed to improve the performance of DFIG´s rotor side convert (RSC) under asymmetrical voltage condition. The symmetrical component theory is employed to decompose asymmetrical three-phase variable such as voltage and current. Simulation results based on Matlab/Simulink of a 1.5 MW DFIG prototype are provided to compare the performance of RSC using traditional control method and proposed control scheme under unbalanced voltage condition. The proposed control strategy shows a promising result for eliminating negative sequence components of stator current and rotor current as well as attenuating torque and reactive power oscillation.