Reduction of Grid Background Harmonics in Three-Phase Inverters by Applying Sliding Mode Control

In grid-tied inverters, the output current distortion must be kept as low as possible since they should meet the IEEE Std 1547. For that reason, grid voltage harmonic distortion is an important concern because it decreases the energy quality in grid-tied inverters. Therefore, a super-twisting sliding mode control algorithm for three-phase grid-tied inverters is proposed in this paper. The main advantage of using the proposed algorithm is its robustness against grid voltage harmonic distortion, which permits to improve the quality of the energy delivered into the grid. Results are obtained by simulating a three-phase inverter tied to a grid polluted with 5 % THD. When PI control is used, the inverter output current reach a 20 % TRD. On the contrary, when the proposed control algorithm is used, the inverter output current is kept below2 % TRD, which complies with the IEEE Std 1547.