Volt/Var Control of Solar Photovoltaic System

The current changes in distribution network topologies due to increasing loads and distributed energy resources cause voltage-increased possibilities for variations. Furthermore, power variation and reverse power flow phenomena may increase terminal voltage variations at the distributing energy resources. As the performance of the distribution power network depends on the voltage profile, controlling the terminal voltage of the resources in the distribution networks has great importance. This paper describes a voltage control within the inverter of a photovoltaic system to keep the terminal voltage magnitude within acceptable ranges through injecting or absorbing reactive power. Also, the inverter prioritizes the active and reactive power based on the terminal voltage level and its power output and controls both active and reactive power independently. This scheme is regarded as volt/var control. The synchronous rotating dq reference frame has been used for controller modeling and design and electromagnetic transient simulation has been exploited to simulate the proposed control system to verify its ability to eliminate the voltage variation.