Optimizing differential protection settings for power transformers

This paper presents an improved methodology to optimize the differential relay settings through simulating different events to the transformer. The aim of this work is to analyze the performance of a numerical differential protection of power transformer through different operating conditions of power transformer which cause unwanted response of the installed differential relay. Simulated cases were performed in the alternative transient program ATP environment which was used to represent the real system. The files were converted into COMTRADE format and trans played it back to a numerical differential relay to verify its proper settings. Results show that the proposed settings methodology ensures security for external fault, inrush, and over-excitation conditions and dependability for different internal faults.