Study on Very Fast Transient Overvoltage of Closing No-load China UHV Transmission Demonstration Project Jindongnan-Nanyang-Jingmen 1000 kV Transmission Lines

Abstract

When the ultra high voltage (UHV) substation used the gas insulated switchgear (GIS) system to switch lines with capacitive current, the pre-breakdown and multiple reignition will occur between switching contacts. Because of discharge characteristics of SF6 and special structures of GIS system, the variations of the electromagnetic transient process and very fast transient overvoltage (VFTO) are very fast and extremely complex. The development process and characteristics of VFTO remain to be dealt with to seek effective suppression measures. The overvoltage of closing no-load long lines on GIS system is analyzed in detail. The simulation model of the very fast transient process of closing no-load long lines on UHV GIS system is established. The VFTO of closing no-load China UHV transmission demonstration project Jindongnan-Nanyang-Jingmen 1000 kV transmission lines is analyzed using electromagnetic transient simulation software ATP-EMTP. The VFTO of closing no-load long lines on UHV GIS system is simulated and calculated, when the system has no additional closing resistors and lightning arresters, additional single stage closing resistors, additional multistage closing resistors, lightning arresters in two terminals of lines, lightning arresters in two terminals and the middle of lines, and additional multistage closing resistors and lightning arresters in two terminals and the middle of lines. The simulation results show that the additional multistage closing resistors and lightning arresters in two terminals and the middle of lines can effectively restrain the VFTO of closing no-load long lines on UHV GIS system.