Photovoltaic systems in low-voltage networks and overvoltage correction with reactive power control

This study deals with the overvoltage problems caused by the increased photovoltaic (PV) penetration in typical rural radial distribution systems, where small PV systems and household consumers are connected. For this study, the authors used an iterative algorithm to solve the power flow problem in radial grids and considered three methods for the correction of unacceptable overvoltages, which are based on different principles. The system under consideration is an almost symmetrical three phase, low-voltage radial network, consisting of nine PV and consumer connection points. The system was simulated for a whole year with a sample time of 15 min, taking into account the variations of the solar radiation and loads. The results verified that the control of reactive power on the line can successfully manage overvoltage issues. The additional demand of reactive power and consequent line losses are used to evaluate various correction methods.