GIS Condition Assessment Method Based on Fuzzy Mathematics Theory

Gas insulated switchgear (GIS)'s property and operation state has a directly influence on the grid safety. Thus state assessment of GIS is badly needed. Most existing GIS state evaluation is based on fault diagnosis, and lack of research on GIS state evaluation methods. In order to develop a more reasonable maintenance strategy, this paper presents a method based on fuzzy membership degree for evaluating the GIS state. Based on all possible failure modes of each structure on GIS, this paper selected the state variables of each fault mode to provide the evaluation index for each structure failure modes. Firstly, for each state variable, its evaluation index fuzzy membership degree of “normal”, “attention”, “abnormal” and “serious” is calculated. Secondly, the weights are assigned to each state based on the analytic hierarchy process. Finally, based on the theory of evidence, all kinds of failure modes are evaluated respectively, and then the state of GIS is evaluated. The method is used to evaluate the state of GIS equipment in operation. Considering the state variables, the different structure of GIS was scored and the membership function was established to correct the weight of each index. It is proved that this method can be used to evaluate the state of GIS in operation. In this paper, a GIS condition assessment method based on fuzzy membership degree is established. The method can be used to evaluate the GIS state comprehensively and effectively.