Controlled switching scheme for photovoltaic generation for reducing overvoltage

Quality of power supply into an electrical network is governed by grid codes, which place restrictions on the voltage characteristics, compatibility levels, limits and assessment methods. In most grid codes it is stated that overvoltage should not exceed 1.05 to 1.15 of the nominal value. Overvoltage is a common issue in networks with Photovoltaic (PV) generation. PV Plants generally have the highest power capacity during mid-day, when the sun is shining. In some countries this corresponds to the time of the day with the lowest load demand. This can cause a scenario where the generation is high but the local load demand is low, this causes current from the PV plant to flow upstream leading to an overvoltage at a point in the system. This paper presents an overvoltage protection scheme to prevent system overvoltage by limiting the amount of power supplied by the PV plant.