Robust and Optimal Single-loop Voltage Controller for Grid-forming Voltage Source Inverters

Abstract

Design and implementation of an optimal and robust single-loop voltage controller is proposed for single-phase grid-forming voltage source inverter (VSI). The objective of the proposed controller is to have good reference tracking and disturbance rejection. Uncertain nature of loads can significantly alter system’s behavior, especially during heavily loaded conditions, and impose an uncertainty in the dynamic model. This deteriorates the robustness of the controller severely. ℋ∞-based controller design is proposed in this article to address this issue. The required objectives of the optimal controller are formulated after modeling the loads as uncertain element of the control system. Time-domain MATLAB/SIMULINK-based simulation study substantiates the fact that the resulting controller exhibits superior robustness in performance during varying loading conditions of VSI than that of the conventional multi-loop control architecture. OPAL-RT based controller hardware-in-the-loop (CHIL) simulations with low-cost controller are conducted to validate the computational footprint of the resulting controller.