Estimation of fast transient overvoltage in gas-insulated substation

摘要

The authors measured FTO (fast transient overvoltages) at various points of a commercial 550 kV gas-insulated substation (GIS) by operating energized disconnectors. Based on the results of these measurements, the possible levels of FTO at various points of the GIS and the probability of occurrence of large levels are discussed. Laboratory tests were also performed by using a recently developed 1 GHz surge sensor to check on the insignificance of high-frequency components due to short-surge impedance discontinuities such as spacers, disconnectors, and short bus branches. Waveforms calculated by rough simulation that ignored the short surge impedance discontinuities are compared with measured waveforms at the commercial substation, proving that simulated FTO levels agreed well with measured values.