A novel harmonic impedance compensator based on POHMR-type RC under gird voltage distortion

Abstract

Abstract The LCL-type grid-connected inverter can suppress high-frequency current harmonics but the inject grid current of the inverter will be worse under grid voltage distortion, therefore harmonic impedance compensation technology is required for this condition. The proportional Multi Resonant (PMR) controller is a feasible method for this purpose, but this scheme needs a large calculation burden and complex design. To overcome these drawbacks, a novel Proportional Odd harmonic Multi Resonant-type Repetitive Controller (POHMR-type RC) is proposed to compensate for the harmonic impedance, which means the grid voltage distortion hardly influence injected grid current. Compared to the PMR controller, the proposed scheme omits the even harmonic resonant controllers and has much more odd harmonic resonant controllers, which also reduces the memory space consumption, calculation burden and controller complexity. The proposed scheme also has better dynamic performance than conventional RC. When the proposed scheme is proposed, the inject grid current is still sinusoidal under strong grid voltage distortion and the transient response is desired. Experimental results verify the feasibility of the POHMR-type RC.