Coordinated control strategy of DFIG under grid voltage unbalance conditions

Abstract

Operation characteristics of doubly fed wind turbine generator system under grid voltage unbalance conditions are analyzed. In order to restrain various pulsations, a coordinated control strategy of rotor-side and grid-side converters of a doubly fed induction generator (DFIG) is presented. Taking the pulsations of electromagnetic torque, stator reactive power and system total output power at double supply frequency (100Hz) as control aims, the required compensation voltages are calculated, then superimposed on the reference voltages of the rotor-side and grid-side converters. Thus the pulsations could be restrained effectively. Finally, the proposed control scheme is implemented in Matlab/Simulink on a 1.5MW DFIG connected to a power grid with unbalanced voltage. Results show that the proposed control strategy can minimize pulsations of electromagnetic torque, stator reactive power and system total output power.