Exponential Phase-Locked Loop Photovoltaic Model for PHIL Applications

PV inverters can adjust active and reactive power to perform voltage regulation in distribution systems. This is commonly achieved using reactive power controls which varying the power factor of the PV inverter. To understand the capability of these devices to perform distribution voltage regulation, power hardware-in-the-loop (PHIL) simulations are often conducted with PV inverter power electronics or phase-locked loop (PLL) models. Power electronics models are difficult to generate without detailed understanding of the inverter control logic; whereas PLL models are effective at abstracting control logic for basic simulations, but often lack realistic dynamic responses provided of actual systems. This paper presents an approach to model PV systems using a combination of a photovoltaic mathematical models and a PLL. The model captures dynamics from changing irradiance and power factor commands. Comparisons between experimental and simulated results are presented for a 3 kW inverter interconnected to 7-bus distribution PHIL model.