Enhanced Power Quality Control for a Grid-Connected Converter under Unbalanced and Distorted Grid Voltage

Power electronics converter, which serves as an interface between the renewable energy resources and power grid, should have a fault ride through (FRT) capability to remain connected to the grid under short-term disturbances and grid voltage faults. Also, a certain amount of instantaneous reactive power is needed to support the grid voltage recovery. In this paper, a novel FRT control algorithm is proposed to support the voltage components at the point of common coupling and limit the total harmonic distortion of the compensated current, which improves the power quality of the grid-connected converter. The proposed method is achieved by controlling the positive and negative sequence fundamental current of the converter as well as its harmonic components under the unbalanced and distorted grid voltage faults. MATLAB/Simulink simulation results are presented to demonstrate the effectiveness of the proposed method.