Surge Propagation in Gas Insulated Substation

Surge propagation performance in a 550 kV gas insulated substation is studied experimentally and by computer simulation using the Electro-Magnetic Transients Program. Extra capacitance added to the system by the components of GIS such as potential devices, branch buses, circuit breakers deform the wave shape of the travelling surges. Because of the effect of those extra capacitances, experimental values of the surge impedance and the travelling velocity are considerably different from the theoretical values. If we take these extra capacitances into account, however, surge phenomena in GIS can be analyzed properly using the theoretical surge impedance determined by physical dimensions of the GIS and the travelling velocity of light. A simple modeling technique to represent GIS in surge analysis is proposed and its applicability is proved in this paper.