Equivalent Waveform Parameters of Switching Overvoltages in UHV Systems.

The standard waveform of switching impulse is important for insulation tests of air gaps as well as external insulation and inner insulation of power apparatus in the power system, which should be consistent with the waveforms in actual power systems. Different definitions of waveform parameters of standard switching impulse are discussed in this paper, and a definition based on breakdown characteristics of air gaps is suggested to obtain the front times. Waveform parameters of switching overvoltages in two 1000-kV ultra-high voltage systems in China are studied and their statistical regularities under different operation conditions are analyzed. Based on the breakdown characteristics of air gaps and the concept of equivalent insulation performance, the typical front times in the system are obtained by a weighted average method. [ABSTRACT FROM PUBLISHER]