Hardware-in-the-loop Assessment of Grid-Forming Inverters for Off-Grid Application of a Fuel Cell System

This paper presents a Controller Hardware-in-the-Loop (CHIL) setup for a two-stage converter that integrates a Fuel Cell (FC) as a storage system within an isolated microgrid. The first stage employs a Three-Leg Interleaved Boost DC/DC Converter (IBC), while the second is a Three-Phase Voltage Source Converter (VSC). The DC/DC stage utilizes Cascade Voltage Control (CVC), while for the DC/AC stage, three distinct grid-forming strategies are implemented to facilitate a comparative analysis of the system's response and its compliance to the IEC 62040–3 standard. The power structure of the system is simulated using the Real-Time Simulator (RTS) HIL 602+ from Typhoon-HIL, with the control strategies embedded on the Digital Signal Processor (DSP) TMS320F28379D - F28379D LaunchPad from Texas Instruments (TI). Verification of the CHIL setup was conducted through various load step tests to evaluate the performance of the control systems. The results demonstrate that only one of the control strategies was in compliance with the specified requirements. Moreover, a comparative analysis between offline and real-time simulations was performed to assess the effectiveness of the CHIL implementation.