Seismic reliability assessment of 500 kV substation systems considering uncertainty in vulnerability parameters

Continuous increase in energy transmission demand has led to the rapid development of high-voltage substations in recent years. Differences in equipment configurations have led to significant variations in seismic performance compared with conventional medium and low voltage substations. To address this issue, this study proposes a seismic performance assessment framework for substations based on fuzzy set theory. The seismic performance of key equipment, gas insulated switchgear (GIS), in a 500 kV substation is evaluated through finite element simulation and seismic vulnerability analysis. The uncertainty of the equipment seismic vulnerability parameters is characterized using membership functions, and the substation seismic performance under different confidence levels is assessed through α-cut analysis. Furthermore, a fuzzy Morris analysis framework is developed by integrating sensitivity analysis to quantify the variation in the importance of each equipment vulnerability parameter with respect to substation seismic performance under different seismic intensities and confidence levels. The results indicate that neglecting the uncertainty of seismic vulnerability parameters may lead to an overestimation of the substation’s seismic performance. The importance of equipment vulnerability parameters exhibits considerable fluctuation under the combined influence of seismic intensity and confidence level, and ignoring these factors may result in misleading identification.