Robust Tuning of Proportional Resonant Controllers for Islanded Three-Phase Inverters With Parametric Uncertainty and Interval Time Delay

This article presents a novel robust tuning method for proportional-resonant (PR) controllers in islanded three-phase inverters, effectively addressing both parametric uncertainties and interval time delays. Existing robust control methods often become unstable when subjected to interval delays, and their performance further degrades when delays occur simultaneously with parameter uncertainties. In contrast, our approach integrates a delay-dependent robustness criterion with value-set and stability boundary analyses, ensuring robust stability under these challenging conditions. The proposed method features low computational complexity, enabling efficient implementation on embedded processors such as digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and microcontrollers with limited processing capabilities. Additionally, it supports systematic controller tuning without requiring precise system reidentification or repeated retuning when parameters vary within uncertainty bounds, thus improving deployment flexibility. The framework’s compatibility with multiple microgrid architectures, including droop control, virtual synchronous generator, and master–slave configurations, enhances portability across different inverter platforms. Experimental validation confirms the effectiveness of the proposed method, demonstrating improved transient response, reduced overshoot, and robust performance in tracking microgrid point-of-common-coupling voltages under varying filter parameters, delays, and load conditions. This article advances robust control in power electronics by providing a scalable and experimentally validated tuning method well-suited for real-time operation in industrial embedded systems affected by uncertainties and time delays.