Risk Evaluation of Minimum Design Temperature of Gas Insulation Switchgear

The risk of extreme low temperature below design temperature is notable challenge to power system. Appropriate design temperature is a crucial factor to guarantee reliability of power system under extreme cold climate. According to existing code, electric equipment should be designed to withstand multiple annual mean minimum temperatures. Since rubber sealing of combined Gas Insulated switchgear (GIS) could shrink notably in extreme cold climate, it could induce extensive SF6 leakage and cause widespread outage of GIS switchgear once the environmental temperature is notable lower than the design criterion. In this paper, observed temperatures in 9 meteorological stations of Shandong province from 1973 to 2016 are analyzed with Generalized Extreme Value (GEV). The risk of exceeding minimum design temperature is evaluated based on mean annual minimum temperatures according to existing code. Moreover, different likelihood of exceeding minimum design temperature of GIS equipment are calculated based on historical minimum temperature and minimum temperature in typical area for comparison. Numerical results suggest that the proposed method provides theoretical support for transmission and transformation equipment minimum design temperature value to optimization.