Stochastic Estimation of Voltage Sags in a Large Meshed Network

This paper presents a method for stochastic prediction of voltage sags caused by faults in a power system. The area of vulnerability must be determined to estimate the expected sag frequency (ESF) at a sensitive load site. However, the area of vulnerability is not easy to identify in a large meshed network. In the paper, the residual phase voltage equations for balanced and unbalanced faults are presented, and an efficient method to determine the area of vulnerability in a large meshed network is described. An ESF estimation method based on information technology industry council (ITIC) curve is also described. The developed method was applied to the IEEE 30-bus test system.