A Least-Square-based RMRAC for Grid-tied Voltage Source Inverters with LCL Filter

Abstract

Renewable energy generation systems commonly use LCL filters as interfaces between them and the grid, aiming to reduce the harmonic content of Voltage Source Inverters. However, the LCL filter presents a relevant resonance peak that can lead the closed-loop to instability. Therefore, aiming to mitigate it, and provide an adequate current injection into the grid, in this paper is presented a Least-Squares-based Robust Model Reference Adaptive Controller. The proposed control strategy can track reference currents fast, while rejecting exogenous disturbances without needing additional control loops. Besides, the controller is robust enough to consider the LCL filter as a first order transfer function during its design, which allows it to use a first order reference model, reducing the complexity inherent to adaptive control strategies. Simulation results are presented to discuss the feasibility of a proposed control strategy for grid-injected current control.