Seismic Vulnerability Analysis of the High-end Suspended Converter Valve Hall Circuit in the ±800kV Converter Station

Suspended converter valve hall circuit is a crucial subsystem within the UHV converter station. It is characterized by electrical equipment possessing attributes of "high, large, heavy, and flexible," making them prone to seismic-induced damage. In order to evaluate the seismic performance and vulnerability of the equipment within this circuit environment, this study establishes a refined finite element model for the high-end valve hall circuit of a specific 800kV converter station. Through time-history response analysis, the seismic response characteristics and potential failure modes under seismic action are investigated. Utilizing Multiple stripe analysis method, seismic vulnerability curves for each failure mode as well as the overall circuit are obtained. A comparative analysis is conducted between the overall circuit vulnerability curve and the circuit vulnerability curve considering each equipment failure as an independent event. This study serves as a reference for seismic reinforcement of critical equipment in existing converter stations at the circuit level, establishing the groundwork for evaluating the seismic resilience of converter stations. The results indicate that the base frequency of the converter valve tower in the valve hall is relatively low, leading to excessive bottom displacement response under seismic action. Moreover, significant stress responses are observed in the electrical component support structures, post insulators, and 800kV wall bushings within the valve tower layers under seismic action. Failure modes of the high-end valve hall circuit include relative displacement of adjacent converter valve tower bases, exceeding stress limits in electrical component support structures within the layers, as well as exceeding stress limits at the bottom of post insulators and 800kV wall bushings. Furthermore, the failures of each equipment are correlated, and treating equipment failures as independent events would greatly overestimate the vulnerability of the circuit.