Measurement of switching overvoltages at substations and on transmission lines in extra high voltage systems

This paper describes a measurement result of switching overvoltages in an actual 275 kV system. The characteristics of the switching overvoltages were grasped from the actual waveforms obtained by measuring voltages at both ends of transmission line and a point on the transmission line simultaneously. The results give the first experimental verification of the conventional view that the switching overvoltages multiple is high at the point on the transmission lines between substations. Furthermore, the relationship between the closing time differences between each phase of the circuit breakers and the magnitude of the voltage due to the switching overvoltages was confirmed from the experimental results. It was verified that the value of the standard deviation of the closing time difference obtained from the experimental results is almost equal to the value obtained analytically.