Resonance suppression method for single-phase LCL Grid-tied inverter based on active damping superposition

LCL filters have superior high-frequency harmonic suppression capabilities and have been widely used in grid connected inverters. In order to suppress the inherent resonance peak of LCL filters, active damping method is usually used. Although this control strategy suppresses the resonance peak, the delay of digital control will cause the inherent resonance point to shift. A control strategy based on virtual impedance model and active damping superposition is proposed to address the above issues. It suppresses resonance peaks while avoiding the displacement of the natural resonance point, and expands the effective damping area to (0, fs/3). Finally, the correctness of the control strategy is verified by building a simulation system and a hardware in the loop semi physical prototype of an LCL single-phase grid connected inverter. The experimental results show that it has good anti-interference ability, dynamic performance, and steady-state performance.