A case study of voltage sag analysis in a utility distribution system

Voltage sags are momentary dips in voltage magnitude that can cause sensitive equipments to trip. Such occurrences have a major economic impact and therefore, the study of voltage sag has become a major effort worldwide. This paper presents a voltage sag analysis implemented on an actual distribution system. The objective of the study presented in this paper is to develop a suitable method for voltage sag analysis in which the method is demonstrated on a practical distribution system. The voltage sag analysis is performed using the commercial software PSS/ADEPT for performing load flow and short circuit simulations. The distribution network is modeled using the actual network data and the transmission system is considered as a source. Faults are introduced at various points in the system, at the buses and along the lines. Simulation results are presented in the form of voltage sag vulnerability areas.