Seismic Performances and Vulnerability Analysis of a 500kV Loop in DC Field

Abstract

The loop in DC field, an essential part of a converter substation, consists of several post insulators and other pillar-type equipment interconnected by rigid bus and flexible conductor. However, it has been found over the past few decades that the great slenderness of pillar-type equipment renders them extremely susceptible to damage during earthquakes. This paper is aimed to comprehensively analyze seismic performances and vulnerability of the loop in DC field and propose improvement recommendations. A 500kV loop in a DC field of a converter substation is taken as the objective to establish a refined finite element model. To obtain the seismic responses, each equipment item of the loop was excited under 30 groups of three-component earthquake records with different PGAs, as well as the loop. The result of simulating process shows that the dynamic responses are relevant to the installation positions. In general, the stress of equipment installed at the end of the loop tends to be higher than that of a single unit, while the equipment installed at the corner of the loop tends to decrease compared to a single unit. Then seismic vulnerability analysis was conducted using the multiple stripes analysis (MSA) method to get the vulnerability curves of the loop and key equipment. The results of seismic vulnerability analysis can be used to predict the failure probability of this 500kV loop under different intensities of earthquakes, and to rank the seismic risk of equipment. Additionally, the seismic vulnerability of the loop is always higher than the vulnerability of any equipment in it.