Risk Assessment of Minimum Design Environmental Temperature for Gas Insulation Combined Electrical Equipment

Electrical conductors and electrical equipment were selected according to the mean of annual lowest temperature, and it was of high likelihood to suffer abnormal lower temperature than its designed criterion. Sealing component of Gas Insulated switchgear (GIS) should be designed based on the criterion of minimum temperature, which could avoid the risk of large-area SF6 leakage accidents causing by ultra-design low temperature. Nine stations in Shandong Province were selected as the research objects, and the temperature observation data from 1973 to 2016 were investigated in the manuscript. The risk level of extreme temperature lower than the design criterion was calculated with Generalized Extreme Value (GEV) distribution according to the annual minimum temperatures determined by the current regulations. Furthermore, the risk of encountering ultra-design low temperature were also evaluated based on the local historical observation minimum temperature and the minimum design temperature in typical areas, which could provide theoretical support and application reference for optimizing the design temperature of power transmission and transformation equipment.