Switching Surge Analysis of an EHV Air-Insulated Substation Using the 3-D FDTD Method

Switching overvoltages on busbars occur during the operation of circuit breakers and disconnectors in power plants and substations. The transient electromagnetic interferences arising from the switching surges may cause disturbances in sensitive electronic devices in low-voltage control circuits and may induce voltages on other busbars grounded for maintenance. To suppress the effect of electromagnetic interferences properly, it is useful to predict surge phenomena and design effective protection methodologies. The finite-difference time-domain (FDTD) method, which is a full-wave numerical approach, has become an effective tool for analyzing surge phenomena in a 3-D arrangement. In this study, first, we propose techniques for applying the FDTD method to the switching surge analysis of an extremely high voltage air-insulated substation. Second, using the proposed techniques, we calculate voltages induced on a grounded busbar due to a restrike at a disconnector during its operation in a 500 kV air-insulated substation and compare the calculated results with measured results for validation.