Time frequency characteristic analysis and simulation of VFTO waveform generated by disconnector switch in GIS

摘要

Very fast transient over voltages (VFTO) with steep front, high amplitude and high frequency are generated during the operation of disconnector switch in gas insulated switchgear (GIS) with no-load short bus. It seriously affects the stability of the power system and the safe operation of related equipment. There is no standard waveform for VFTO, only the provisions of the rise time and characteristic frequency at different time. But the range of provision is very large, which is not applicable to specific GIS equipment. This paper theoretically analyzes the characteristics of VFTO waveform, such as the rise time, characteristic frequency and so on, influenced by the components of GIS. And the PSCAD simulation is carried out to verify the results of the theoretical analysis. The Wigner-Ville distribution (WVD) method based on empirical mode decomposition (EMD) is also proposed to the frequency spectrum analysis of VFTO. All work provides important reference to grasp the characteristics of VFTO and to guide the monitoring of the operation of disconnector switch in GIS.