Application of Duval Pentagon in State Diagnosis of On Load Tap Changer

Abstract

A comparative analysis on the effect of two DGA methods, Duval Pentagon and Duval triangle, in identifying abnormal OLTC was carried out. The corresponding area of Duval Pentagon corresponding to the normal state of OLTC was determined, and Duval Pentagon was used to judge the OLTC of UHV converter transformer. The results show that the Duval Pentagon can identify the normal and abnormal states of on load tap changers. More than 95.5% of the on load tap changers are in the low energy discharge area numbered D1. The identification results of 245 on load tap changer states show that the accuracy of normal state of Duval Pentagon is higher than that of Duval triangle, which can be used as an auxiliary criterion for on load tap changer state diagnosis.