BN-based seismic risk analysis and mitigation strategy for UHV converter station

Ultra-high voltage (UHV) converter stations are critical nodes in power grids. This paper proposes a probabilistic framework for assessing and mitigating the seismic risk of UHV converter station systems to enhance the seismic performance of the grid. First, a Bayesian network model for the system functionality of UHV converter stations was established based on the enumeration of equipment failure scenarios. Conditional probability tables (CPTs) were used to represent the causal relationship among subsystems and system functionality. Inference calculations were conducted using Bayes' theorem. Then, the definition of system seismic loss risk distribution was proposed to assess the seismic risk of the system over its entire lifespan. The feasibility of this framework was validated using a specific UHV converter station, yielding analytical solutions for the probability distribution of system functionality and seismic vulnerability curves. Additionally, the cost-effectiveness of several risk mitigation strategies was assessed. A cost-benefit analysis was performed from the perspectives of both the expected loss of a single earthquake and the life-cycle cost. The framework comprehensively considered the constraints imposed by series, parallel, and bypass control devices on the system's functionality. It was revealed that the seismic loss risk for UHV converter stations exhibits a characteristic of low probability but high loss.