FAULT ANALYSIS OF AN INTERNAL FAULT ON A SYNCHRONOUS GENERATOR

Abstract

This work consists essentially of two parts. In the first part the general principle of analysis of all types of internal faults in a synchronous generator is discussed. Although a salient pole synchronous genera- tor is considered, it has been indicated how the equations should be modified when considering a cylindrical rotor synchronous generator. The analyses have been done using the symmetrical components. The second part consists of a mathematical, analysis of a short-circuit between one parallel path of phase A and another parallel path of phase B of a 141 MVA. 120MW, 0.85 pf turbo-generator having two parallel paths per phase. The object of the analysis is to predict the fault currents flowing in the various parts of the armature windings. A detail analysis of an internal line-to-ground fault has been performed by V.A. Kinitsty in 1965 and the method of analysing a line-oto-line fault has been suggested. In the case when the numbers of turns between the fault points and the neutral in the two faulted branches are not the same the suggested method becomes very cumbersome, and the application of Maxwells' Loop Equations have been found to be simpler•