Protection from Internal and External Faults using Differential Protection Scheme for Power Transformer and Validation using Simulation Model

Transformer is an important component in the power system both at transmission and distribution level. Although, transformer faults are less prominent than either line or equipment faults but if unattended can cause major damages to the subsequent interconnected equipment and system. The ratings for distribution level are typically lower than at transmission level. Irrespective of the size of the transformer, the differential protection scheme becomes an ideal choice for engineers. This project mainly identifies the importance of differential protection of transformer by simulating adverse (fault) conditions and operating conditions (inrush) of transformer using ATPDraw modeling. An integrated use of differential relay protection scheme for transformer is simulated using MatLab/Simulink. Several challenges in fault simulation in both ATPDraw and MatLab during initial studies were mainly related to design parameters, and were subsequently addressed by detailed literature review using IEEE researchers. With insights developed in relay protection from classroom notes and textbook, modeling and simulation of fault scenarios namely: internal and external faults, were performed. The goal and scope was further refined to identification of differential currents during the faulty conditions and studying operation of relay designed using basic Boolean logical approach. In the final analysis, results for no fault and fault conditions with relay operation are presented and a need for design of relay sensing the harmonic components is included as part of future scope of this work.