Volt-Var as Control Strategy of Grid-Tied Smart PV Inverter

The increasing penetration of distributed energy resources (DERs) poses several challenges for network control. Voltage issues are the main drawback of high DER penetration, especially in photovoltaic (PV) systems. Moreover, ensuring a balance between electricity production and consumption is still a real challenge for the power grid. In response to such constraints, PV inverters should support grid voltage. In this context, inverters play a key role in adjusting the power injected into the grid according to variations in demand and production. Conventionally, inverters were operated with a unit power factor. Still, advanced inverters, called smart inverters, can even supply reactive power to the grid to overcome voltage problems. These advanced functions enable solar PV inverters to monitor and communicate system status, automatically providing auxiliary services to the grid. Thus, advanced inverter control is essential to prevent imbalances that could lead to voltage fluctuations or grid instability. Specifically, Var-priority and Watt-priority modes were designed in the paper for a comparative study. Simulations were conducted to validate the modes' effectiveness in addressing voltage issues under grid disturbances.