A Voltage Regulation Strategy by Grid-Connected PV Inverters in Low-Voltage Networks

In allusion to out-of-limit voltage at grid-connected point caused by grid-connection of photovoltaic(PV) system and raising the penetration rate of PV system on power grid, it is possible to fully utilize the reactive power regulation ability of grid-connected PV inverter to provide reactive power support to power grid. For this purpose, in the viewpoint of voltage drop the voltage variation at grid-connected point before and after the grid-connection of PV system is researched, and the reactive power control strategy given by Verband Deutscher Elektrotechniker(VDE) is analyzed in depth. On this basis, a reactive power control strategy based on voltage amplitude at grid-connected point and active output of PV system is proposed. This control strategy inherits the advantages of reactive power control strategy given by VDE, and under the proposed control strategy all PV inverters participate power grid voltage regulation, and under the premise of maintaining the grid voltage within the specified range the total absorbed amount of reactive power is the lowest and the active and reactive loss of power grid are minimized. The validity of the proposed control strategy is verified by case study results.