Multiloop control method for high-performance microgrid inverter through load voltage and current decoupling with only output voltage feedback

This paper proposes a multiloop controller with voltage differential feedback, and with output voltage decoupling and output current decoupling by only using the output voltage feedback. The output voltage differential feedback loop actively damps the output LC filter resonance and thus increases the system stability margin. The decoupling of output voltage and current makes the inner loop equivalent to a first-order system and thus improves the system dynamic response to load disturbance. The pole placement technique has been used here to design the inner loop and outer loop gain, with considering the effect of system control delay. The proposed control scheme possesses very fast dynamic response at load step change and can also achieve good steady-state performance at both linear and nonlinear loads. In addition, it only uses the output voltage as the feedback variable, which reduces the system complexity. The theoretical conclusion has been verified by simulation and experiment results. This method is proved to be an effective solution for voltage control in stand-alone mode of three-phase microgrid inverters.