Impact of Voltage Sag on a Bus Due to Transient in Induction Motor Drive System

Power quality has become one of major issue in modern power system due to with increase in nonlinear loads, addition of large number of distributed generation source and increase of sensitivity to power quality variation. Due to highly interconnected nature of modern power system any problem in one part of system can have serious consequences. This paper describes the variation of voltage on a bus due to switching of dynamic load on different bus within power distribution network. Here special prominence is given to loading and unloading of induction motor drive system. When induction motor drive is loaded, it causes steep fall in the voltage at nearest bus, this drop is function of impedance of transmission line. For short transmission line, voltage drop is minimal but in case of longer transmission line, effect of line capacitance comes into picture. Results shows that for short line, voltage drop is less but when longer transmission line is used, voltage drop is more and voltage sag becomes prominent. Relation between voltage sag and line capacitance is been investigated.