A novel GIS breakdown location method based on natural frequency of transient voltage

Abstract

During on-site withstand voltage tests of gas-insulated switchgears (GIS), once a breakdown occurs, it is hard to locate the breakdown position due to the intricate branch structures and minimal breakdown energy. The existing methods may require the placement of a large number of sensors with unsatisfactory accuracy, which adversely affects the process of inspecting and repairing, as well as the subsequent tests. To address this issue, this paper introduces a novel GIS breakdown location method. This method is predicated on the natural frequency of the transient voltage caused by the breakdown. The relationship between the breakdown position and the natural frequency is first derived, which is referred to as the location equation. Then, the natural frequency characteristics are discussed from both mathematical and energy perspectives. Based on these characteristics, the location method is proposed that utilises the location equation and the frequencies at two measurement points. The results of the laboratory experiments demonstrate the accuracy of the method and certain advantages over the ultrasonic method. Further, the effectiveness of the method in GIS and gas-insulated transmission lines (GIL) with complex structures and high voltage levels is also confirmed by simulation cases and field experimental data.