Analysis of VFTO signal characteristics under the operation of isolating switch in GIS

During the operation of the isolating switch in the GIS, due to the relatively slow contact movement speed, multiple pre-and heavy breakdowns occur in the gap of the isolating switch fracture, resulting in steep traveling waves, and multiple reflections and superpositions occur at the discontinuity of the GIS wave impedance. And then very fast transient over voltage (VFTO)appears. The core question of this paper is an electromagnetic interference. This paper is about the measurement mechanism of three-dimensional transient electromagnetic field, and realizing three-dimensional magnetic field synthesis of single-point data collected on the spot. Then through the correlation analysis of the signal, it is demonstrated that when studying the frequency characteristics of the VFTO waveform, it can be decomposed into the theory of spectrum analysis of the VFTO pulse waveform of each breakdown, and then the breakdown signal is analyzed for the statistical characteristics and time-frequency spectrum analysis. It characterizes the characteristic analysis of the entire VFTO signal. The transient radiation field of GIS switch operation may cause strong electromagnetic interference to the online monitoring digital terminal. By studying the frequency components of transient voltage, it can play an important role in the protection of electromagnetic compatibility and smart grid EMC.