Voltage Rise Mitigation in 0.4 kV Power Distribution Lines Powered by Multiple Residential Photovoltaic Solar Plants

This research addresses the challenge of a voltage increase on 0.4 kV power distribution lines with high photovoltaic solar plants penetration. Connecting a large number of photovoltaic solar plants to power distribution lines causes a significant voltage rise, which leads to the automatic shutdown of these plants in emergency mode. This seriously hinders the use of solar energy. PV solar plant inverters use reactive power generation or consumption technology to regulate the voltage level, but it is effective only when the line X/R ratio is sufficient. This publication proposes an innovative and easily implemented method for voltage rise mitigation, based on the connection of additional inductive chokes to the power distribution line. The method will expand and fully implement existing voltage regulation measures in already installed PV solar plant inverters, which other methods do not. A methodology for selecting the additional inductance value is presented. Reactive power control methods are compared, and recommendations for the use of methods are presented. An equation is proposed for calculating the coupling point voltage of a PV solar plant inverter using the Q = f(U) diagram. The effectiveness of this method is based on mathematical calculations, simulation, and experimental verification, using typical Lithuanian power distribution lines configurations.