Stochastic evaluation of voltage sag in power system network considering effect of photovoltaic generation

The present scenario need is to integrate renewable energy sources (RESs) with power grid to address the increasing concerns of environmental issues and energy demand. Apart from renewable energy integration, the quality of power delivered is also important. Among all power quality issues, the most common power quality issue is voltage sag which significantly affects industrial, commercial, and domestic users. This paper estimates the frequency of voltage sag using analytical method. This paper also analyses the change in frequency of occurrence of voltage sag when power system network is integrated with photovoltaic system. This stochastic evaluation of voltage sag is performed for 30-bus IEEE subtransmission system. The voltage sags are evaluated at various observation buses with and without integration of photovoltaic generation. The numbers of photovoltaic generating plant are increased in order to observe variation in frequency of occurrence of voltage sag. The results are presented in terms of frequency of occurrence of voltage sag and area of vulnerability for transmission network.