A power hardware-in-the-loop framework for advanced grid-interactive inverter testing

This paper presents a power hardware-in-the-loop (PHIL) framework for testing advanced inverter features such as voltage regulation and frequency response that interact dynamically with the electric grid. The PHIL model simulates grid voltage dynamics using a simplified Thévenin-based model and simulates grid frequency dynamics using a turbine-governor model including droop, inertia, and damping. Also presented are a statistical analysis of short-circuit impedances in the IEEE 8500-node test feeder, and analytical justification for approximating Thévenin impedances at inverter connection points as short-circuit impedances. Test results are presented for two inverters performing volt-VAr control, high-frequency power curtailment, voltage and frequency ride-through, and abnormal voltage disconnection while connected to the PHIL system. Results confirm advanced grid support functions have the desired effects when performing voltage regulation and high-frequency power curtailment while riding through large voltage and frequency transients. Some PHIL tests presented here replicate IEEE 1547.1-style conformance tests; no evidence is seen that grid dynamic response emulation affects the results of such conformance tests.