The increasing penetration of inverter-based resources (IBRs) has intensified the need for smart inverters capable of supporting power system stability in microgrids with high levels of distributed PV generation. This paper presents the design and hardware-in-the-loop (HIL) validation of a droop-controlled grid-forming (GFM) inverter for a 100kW photovoltaic (PV) system.
A high-fidelity model of the PV array, converter interface, and grid coupling was implemented in MATLAB/Simulink and executed in real time on an OPAL-RT OP5700 platform. The inverter was evaluated under islanded and grid-connected conditions through step-load disturbances, three-phase short-circuit faults, and low-voltage ride-through (LVRT) compliance testing.
Results show that the inverter maintains stable frequency and voltage during small disturbances, recovers within 0.5s after a three-phase short-circuit fault without load shedding, and satisfies the New Zealand Grid Code LVRT requirement without the use of FACTS devices. These findings demonstrate the feasibility of small-scale GFM inverters to contribute ancillary services and improve stability in renewable-dominated microgrids.
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