Design of a Seismic Hazard Risk Assessment Model for EHV Transmission Grid

The Chi-Chi earthquake is one of the biggest earthquake occurred on September 21, 1999 in Taiwan and caused a huge damage to the power system. There were 3,741 EHV towers at that time, and a total of 307 EHV transmission towers were damaged by the earthquake. Therefore, seismic hazards for EHV transmission towers should not be underestimated. In particular, earthquakes are a significant threat to EHV transmission towers especially in Taiwan. Thus, this study establishes a quantitative risk assessment model for the seismic hazard analysis on the EHV transmission tower structure. The real form of tower model was built in finite element analysis software SAP2000. In order to assess the damage level of towers, the fragility curves of towers were established by nonlinear dynamic analysis. The fragility curves can describe the probability of structures at different damage levels caused by the earthquakes. The damage level of an EHV tower after an earthquake can be accurately estimated by the proposed model, and emergency repair operations can be arranged. In addition, before an earthquake occurs, the proposed model can be used as a tool for estimate the damage potential of EHV towers.