Effects of Zero Sequence Modeling and Transposition on Switching Surge Overvoltages

Zero-sequence frequency dependent parameters for a transmission line with both ground wires and earth return paths and the effects of nontransposition are modeled on an analog transmission system simulator. The effects of this detailed modeling on the overvoltages experienced by a 200 mile 765 kV transmission system. link are investigated, for a variety of switching surge and fault initiation operations, in terms of the resulting overvoltage probability density distributions.