Statistical switching overvoltage analysis of the first BC Hydro phase shifting transformer using the Electromagnetic Transients Program

A 400 MVA 230 kV phase-shifting transformer (PST) is to be installed in the Nelway substation of the British Columbia Hydro (BC Hydro) transmission network in 1990. Due to the unique design and construction of the PST, a detailed analysis of the switching overvoltages for insulation coordination was required. This analysis, using the Electromagnetic Transients Program (EMTP), is described. For accurate representation of the distributed and untransposed nature of overhead transmission lines in the vicinity of the Nelway substation, the untransposed line model developed for the EMTP is used. Statistical switching studies are also performed using the EMTP. The scanned maximum overvoltages obtained from the statistical runs are used to determine the energy requirement of the metal oxide surge arresters. The overvoltage protection level of the PST and the station equipment is also investigated by statistical analysis.<
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