Probability Based Vulnerability Analysis of UHVDC Supported Filter Circuit Under Earthquakes

The direct current (DC) supported filter circuit is a critical electrical circuit in an ultra-high-voltage (UHV) substation, but its unique structural properties render it susceptible to damage during significant earthquakes. In order to investigate the seismic vulnerability of a supported filter circuit, numerical modelling was performed on an 800kV supported filter circuit. Modal analysis and seismic response time history computation on the circuit were performed using the numerical model. In addition, a seismic vulnerability analysis of the circuit was conducted. The results show that the first three order frequencies of the model were calculated as 1.354 Hz, 1.471 Hz and 1.621 Hz. Coupling has a beneficial effect on the seismic performance of pillar equipment and LV equipment capacitor C3 and reactor L3. However, the coupling amplifies the root stress responses of support insulators of capacitor C2 and reactor L2, and the stress response of transformer T1 in the LV region. The order of vulnerability of equipment in the circuit system is: the underlying insulator of the DC filter Cl> electronic transformer T2> pillar insulator PI1-4> disconnector Q1-3.