Current control of grid-forming LCL-type inverter with a fully actuated control strategy

The grid-connected inverter is a key component in the new energy generation system. LCL-type inverter has the superior high-frequency harmonic suppression capability compared to the other filters. But LCL inverter is a third-order coupled nonlinear system and is difficult to control adapting the traditional method, especially to suppress inherent resonance problems. The high-order fully actuated (HOFA) control is based on system physics model, can deal with high-order and nonlinear terms effectively. This paper performs a strict-feedback transform the model of LCL inverter system, and then get the HOFA model of the LCL inverter by the feedback linearization. Utilising the HOFA model, we proposed an HOFA control strategy aimed at achieving rapid and precise control for the grid-connected current tracking and suppressing LCL resonance. Adopting the proposed control, the traditional voltage and current loop is replaced and the problems of coupling and nonlinearity can be handled more easily. The compared simulations and the hardware-in-the-loop (HIL) testing with RT-Box verified the effectiveness of the proposed approach.