A simple and robust method for designing a multi-loop controller for three-phase VSI with an LCL-filter under uncertain system parameters

Voltage source inverters (VSIs) with an LCL-filter are commonly used in practice, especially in microgrid systems. Exactly determining the control coefficients for the controller of a VSI with an LCL-filter is an important and challenging issue. However, existing LCL-filter-based inverter systems usually assume that all system parameters are determined accurately and remain constant over time, which is not true in real situations. Variations in the system parameters are known to possibly seriously degrade the performance of LCL-filter-based inverter systems. For efficiency and robustness, this paper proposes a simple and robust method for the generalized controller design of a three-phase VSI with an LCL-filter system that can address deviations in system parameters. The proposed method can be effectively used to design the controller of an LCL-filter inverter system for fixed and varying system parameters. Simulations and experimental results are presented to validate the correctness and effectiveness of the proposed design method.