A Unified Stability–Accuracy Co-Design Framework for Reliable Power-Hardware-in-the-Loop Testing of Grid-Connected Inverters

This article presents a unified stability–accuracy co-design framework for power-hardware-in-the-loop simulation (PHILS) of grid-connected inverters. PHILS enables realistic inverter evaluation by integrating a real-time simulator (RTS), power amplifier (PA), measurement sensors, and a device under test (DUT), but computation delay and hardware dynamics can significantly degrade stability and accuracy. To address these challenges, this work develops a systematic methodology incorporating PHILS component modeling, interface selection, and filtering and compensation design. Open-loop transfer-function analysis is employed to evaluate stability through gain and phase margins, while closed-loop analysis is used to quantify magnitude and phase accuracy and guide the co-design process. The framework is experimentally validated using a 500 W laboratory prototype emulating a 250 kW grid-connected inverter model. The resulting configuration achieves gain and phase margins of 11.1 dB and 90.2°, respectively, with magnitude error below 1% up to 570 Hz and phase error below 10% up to 265 Hz. Under active-power variations, the active-power error remains below 1%, while the maximum reactive-power error is 5.88%. These results demonstrate the practical applicability of the proposed stability–accuracy co-design methodology under the tested conditions.