Area of vulnerability for prediction of voltage sags by an analytical method in indian distribution systems

This paper proposes an analytical method for voltage sags prediction in distribution systems. The method is based on the ZBus matrix of the distribution network, from which one can immediately build a second matrix that can be called the ldquovoltage sags matrixrdquo as it compactly provides valuable information about voltage sags throughout the distribution systems. The paper also describes graphical ways to present the effect of a fault on the distribution systems and the area where faults cause severe sags on a given load: affected area and area of vulnerability respectively. An Indian distribution system is used to illustrate the ideas.