Seismic Risk Assessment of Power Substations

Power networks are among the most important infrastructures that without them, industrial, economic and social procedures will halt. Therefore, they should be planned for the most difficult conditions to provide services with minimum disruption. Power substations are of great importance to a power network, because any disruption in their components can produce extensive problems through the network and result in power failure in a large area. Hence, vulnerability assessment of power substations and planning for reducing their vulnerability is fairly essential. Earthquake can inflict serious damages to power substations. Due to inappropriate anchors, most of the power substation components in Iran are vulnerable to earthquake. There are several methods for seismic vulnerability assessment of substations such as ALA as a qualitative procedure and HAZUS and RISK-UE as quantitative methods. In this paper, seismic vulnerability of the Qazvin 1 and Minoodar substations, located in the city of Qazvin-Iran, is assessed using ALA, HAZUS and RISK-UE methods and the probable damages of earthquake to power substation components are discussed considering two earthquake scenarios. Initially, the target performance and assessment metrics of the mentioned substations are studied with ALA and the necessity of quantitative analysis is determined. Then the quantitative analyses are conducted with HAZUS and RISK-UE methods and the results are compared. Finally, direct economic consequences are determined and risk analyses are performed and the reduction in the risk due to hardening based on implementation of proper seismic anchorage is determined. The results show that the implementation of seismic anchorage reduces the seismic risk about 41.4 and 34.2 percent for Qazvin 1 and Minoodar substations respectively. The effects of seismic risk reduction in the studied substations could be more emphasized considering the indirect tangible and intangible losses that are resulted from power outage and interdependency between infrastructures. The study may also be an example of a range of qualitative to quantitative investigations of lifelines for seismic risk reduction studies.