Study of Transformer Faults and Protection

Abstract

This thesis describes different types of transformer faults and its protection scheme for transformers. Mainly, distribution type transformer has been considered. The first part of the thesis provides the background for different types of transformers faults and the differential thesis provides the background for different types of transformer faults and the differential protection schemes currently applied. After that we have focused a special sector that is a method of modeling transformer with internal winding faults. An internal fault is simulated by dividing the transformer winding into several sub-coils. The simulation of the terminal voltages and currents is based on known leakage factors between the various coils of the distribution transformer. These leakage factors are calculated by using a simple method analyzed in this paper. Then we analyzed a method for protecting turn to turn fault of transformer. Problems for the differential protection caused by transformer inrush currents and harmonics are also discussed. We have also analyzed various vector group tests and a technique for determination of vector group of different types of transformer and make them suitable for parallel operation