Measurement and Simulation of Disturbance Voltage Generated by VFTO in UHV GIS Substation on the Secondary Cables

Abstract

When GIS disconnect switcher is operated,the electric arc breakdown and reigniting between switchgear contacts will produce very fast transient over-voltage(VFTO).VFTO is characterized by high peak value,short rise time and wide frequency range.The transient electromagnetic field that generated by VFTO would coupling on the secondary cable through space or conducting.a dedicated measurement system that suit for strong electromagnetic environment was developed,and the system could be used to measure the induced voltage on secondary cable caused by VFTO on the UHV GIS apparatus,then the induced voltage in time domain and frequency domain was analyzed.The frequency domain model of the shielded cable that combined transmission line method with field-to-line theory was established.The study result shows that in the condition of both grounded at the two ends or grounded at the control room side,the disturbance voltage on the secondary cable is significantly inhibited.The measurement and simulation results could be the reference for the research on the secondary system in UHV GIS substation.