In recent years, gas-insulated switchgear (GIS) substations have become widely used in power systems. Due to their compact structure, extremely high oscillation frequencies are prone to extremely high oscillation transient overvoltages or very fast transient overvoltages (VFTOs) when the isolating switch or circuit breaker is operated. The characteristics of these special fast transient processes in GIS and the effect of hybrid reactive power compensation (HRPC) on these fast transient processes were studied. A simulation of the GIS model was established, and based on the transient model of HRPC and the theory of the transmission line, the effects of VFTO produced by HRPC switching operation and the parameters of HRPC on VFTO were studied and the differences in the characteristics of VFTOs in substations with or without HRPC. Based on the conclusions of our study on the influence of HRPC on VFTO, the inhibitory effects of a ferrite magnet ring and an inhibitor busbar on VFTO were verified.

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In recent years, with the vigorous construction of the ultra-high voltage grid, the line operating voltage level has become higher and higher. In order to ensure the safe operation of the transmission line, the line insulator string has a length of several tens of meters, and traditional manual testing has been unable to meet the requirements. With the continuous maturity of wireless communication technology, electromagnetic compatibility technology, sensor technology and other comprehensive technologies, it is necessary to develop an insulator string detection robot to replace artificial insulator detection work on UHV transmission lines. By means of wireless sensor communication technology, electromagnetic compatibility technology, video image technology and many other technologies, the insulator detection robot designed in this paper has realized automatic detection of zero resistance value of insulator of UHV transmission line. In addition, the real-time monitoring of insulator resistance value can be carried out through wireless communication to achieve the purpose of timely alarm. In addition, the robot's motion status and the insulator's field status can be observed in real time through video image acquisition. The insulator detection robot designed in this paper realizes the automatic detection of the zero value of insulator of the UHV DC transmission line. It can adapt to the UHV AC DC transmission line with different voltage levels by changing the length of the climbing arm, and at the same time adapt to the climbing detection of the string insulator of tension tower and the vertical insulator of the straight tower. The problem that the insulator string of the UHVDC transmission line can not be automatically detected by electric charge has been solved. It greatly improves the efficiency of insulator detection and the automation level of power transportation maintenance, reduces the cost of human transportation, and creates higher economic and social benefits.