The role of equipment in seismic risk of power substations

Seismic vulnerability of power substations, one of the key components of a power network, has been observed in previous earthquakes. Generally, a power substation is comprised of several components such as the main power transformer (PTR), circuit breakers (CBs), disconnecting switches and post insulators. Each of these has its own functionality and the overall performance of the power substation depends on these components. Previous studies have mostly focused on the seismic vulnerability of power networks rather than on the interdependencies in a single substation. In this paper, the seismic vulnerability of power substations in previous earthquakes is discussed first, and then some practical techniques for preventing seismic vulnerability are presented. Finally, by considering experts' practical opinions about the functional role and importance of each of piece of equipment in a power substation, a deterministic approach using the analytic hierarchy process is introduced, which can estimate the proportional contributions of the related equipment to the seismic performance risk of a substation. The operational significance of all the equipment in a power substation is not the same; under emergency conditions, there is a fundamental need of such pieces of equipment as PTRs, CBs and also bus bars.