A rapid seismic fragility and risk analysis of electrical substation equipment considering modeling uncertainties

Abstract

This study aims to evaluate the influences of modeling-related uncertainties on the seismic response and fragility function of the four vulnerable components of electrical substation equipment, taking into account the dynamic interaction between apparatuses via bus slider-rigid bus conductors. The 3D finite element model for interconnected disconnect switch- circuit breaker-current transformer-surge arrester system is developed in OpenSees software. A sensitivity analysis is conducted to evaluate and rank the importance of individual random variables on the seismic responses. To incorporate modeling uncertainties into the failure fragility function, probabilistic structural interconnected simulations are generated using the Latin hypercube sampling technique. The fragility curves for each apparatus in the connected system are derived using incremental dynamic analysis (IDA). An efficient procedure based on the endurance time (ET) method is presented for estimating response distributions and fragility parameters of the interconnected apparatuses while considering modeling uncertainty. The proposed approach provides acceptable results compared to those from the IDA while tremendously reducing computer run-time. This investigation also puts forth a rapid detailed seismic risk analysis framework using scenario sampling analysis. To this end, the ET response distributions are exploited as equipment response models within reliability-based risk analysis. Results indicate that the damping ratio and porcelain elastic modulus have a substantial effect on the seismic responses of equipment. In addition, modeling uncertainties affect the median and dispersion values of the failure fragilities by up to −5.9% and +22% on average for all equipment cases, respectively. According to the loss curves, it is observed that the circuit breaker contributes the greatest to the system's overall loss, whereas the surge arrester contributes the least.