A Proportional + Multi-Resonant Current Controller for Grid-connected Inverters under Unbalanced Grid Voltage

摘要

The traditional grid-connected inverter (GCI) has the disadvantage of high total harmonic distortion under the condition of unbalanced and distorted grid voltage. On this basis, a novel GCI control strategy is proposed in this paper. Firstly, a second order generalized integrator is built in the αβ coordinate to realize the grid voltage phase shift 90° and separate the positive-and negative-sequence. Then, the grid current reference command of the GCI is derived. Secondly, a proportional + multi-resonant (PMR) controller, which does not need positive-and negative - sequence separation of the grid current, is employed to achieve zero current error control and improve the grid current power quality. Finally, simulation results demonstrate the effectiveness of the proposed scheme under the condition of unbalanced and distorted grid voltage.