Study on the Influence of Disconnector Characteristics on Very Fast Transient Overvoltages in 1100-kV Gas-Insulated Switchgear

Abstract

Very fast transient overvoltage (VFTO) generated during switching of the disconnector (DS) in gas insulated switchgear (GIS) may threaten the insulation of electrical equipment. DS characteristics are important influence factors for VFTO. To study the influence of DS characteristics on VFTO in GIS, experimental study was conducted in two established full-scale 1100kV GIS test circuits. More than 1800 tests of switching of DS in test circuits were carried out. In one circuit, the effect of operating speed on VFTO amplitude and trapped charge voltage were studied by changing operating speed of DS. The results show that, the amplitude of the trapped charge voltage and VFTO decreases with decrease of operating speed. Operating speed was proposed to be 0.5 m/s ~ 0.8 m/s to suppress VFTO.In the other circuit, VFTO characteristics were studied by tests under two connection ways of DS. One is that the moving contact is connected with AC power source, and the other is that the fixed contact is connected with AC power source. The results show that, the connection way will affect the breakdown characteristics of the DS, and then affect the polarity of trapped charge voltage. However, the connection way has little influence on the amplitude of VFTO. The achieved results provide a reference for the design and optimization of DS in GIS.

Multi-spark modeling of very fast transient overvoltages for the purposes of developing HV and UHV gas-insulated switchgear and of conducting insulation co-ordination studies

“…[20]; b) test set-up according to IEC Std. [20] established for development tests of the 1100 kV GIS disconnector; c) test set-up at the Wuhan 1100 kV GIS station [17,27] M. Szewczyk set-ups, for which the multi-spark approach to VFTO modeling was employed, as presented in this paper. The test set-up in Fig.…”

“…The test set-up shown in Fig. 11c was established by the State Grid Corporation of China (SGCC) in Wuhan's 1100 kV GIS station [17,27] for research on and testing of 1100 kV GIS disconnectors of different designs. The test set-ups shown in Fig.…”

“…11 served for performing VFTO analyses in several works that have been conducted based on VFTO measurements and simulations, as reported e.g. in [4,8,9,11,17,18,23,27,28]. For modeling the entire VFT process, the multi-spark approach as presented in this paper was employed.…”

Numerical Analysis of a Spiral Tube Damping Busbar to Suppress VFTO in 1000 kV GIS

“…During the next closing operation of the disconnector, due to the slow contact speed, the first pre-strike occurs when the source side and the load side have the same voltage with different polarity, where the load-side voltage is TCV resulting from the previous operation. The main challenge in the TCV approach is the optimum design of the disconnector which should be considered to achieve significant VFTO reduction with an acceptable sparking time, as explained clearly by Chen, W. et al [24].…”

Performance improvement of MO surge arrester using high gradient arrester block against VFTOs

“…In contemporary years, the evolution of extra high voltage (EHV) and ultra-high voltage (UHV) transmission technology has been rapidly augmented across the world [1]. On account of this, the magnitude of VFTO vastly exceeding the standard lightning impulse withstand voltage (LIWV) for UHV systems, and it upsets the insulation of connected equipment, such as transformers, bushings, and secondary equipment because of the high rate of rise in voltage (dU/dt) [2].…”