Study of Transformer Winding Resonance Phenomenon by Lightning Surges at Substations

Abstract

In recent year, there is the example that oscillating overvoltage occurs by the lightning strike to transmission line, and the transformer in substation breaks down. Lightning surges at two 77kV substations have been measured from 1990 to 1993. In this paper, I analyze the lightning surge waveform measured at substation including the transformer winding and show the relationship between the voltage of transformer neutral point and vibration frequencies of surges. Then, I show an outbreak condition of the qualitative resonance-related overvoltage by a frequency and the waveform pattern using XTAP (eXpandable Transients Analysis Program) and show the result that I inspected about a suppression effect of the transformer neutral point voltage with transmission line arrester and neutral arrester.