Seismic Performance Analysis for the LADWP Power System

This paper describes a method of seismic performance evaluation for an electric power system. The method is then utilized for evaluation of system performance degradation of LADWP's power network damaged by the 1994 Northridge earthquake by comparing its performance before and after the earthquake event. Similarly, the method can evaluate quantitatively the effect of various measures of rehabilitation or retrofit performed on equipment and/or facilities of the power system. This is done by comparing the system performance with or without the rehabilitation. In this context, the results of experimental and analytical studies carried out by other researchers are used to determine the possible range of fragility enhancement associated with the rehabilitation of transformers in terms of base-isolation systems. More specifically, 47 earthquake scenarios are used to develop the risk curves for the LADWP’s power transmission system. The risk curve plots the annual probability of the system’s capability for power production decreasing to a range less than a specified level due to earthquake damage. The risk curve can then be correlated to economic impact of the reduction in power supply due to an earthquake. Recovery aspects of the damaged power system must be considered from this standpoint.