Strategy of cutting and mitigating the disaster chain for secondary and derivative accidents of overhead line failures and wildfire

Forest fires can be triggered by the failure of overhead power lines, especially in forests that are prone to wildfires and have dense power transmission networks. The spread of such fires can, in turn, endanger the safety and stability of nearby power infrastructure. Understanding the evolution of forest fires and the mechanisms behind secondary and derivative accidents is essential for implementing risk control at key nodes within the disaster chain. This is crucial in reducing the likelihood of disaster occurrence and the severity of its consequences. However, research on secondary and derivative disaster chains related to forest fires remains limited, and no existing studies have addressed the coupling induction between forest fires and overhead line failures. This gap may lead to risk control measures that are inadequately targeted.

In this study, a secondary and derivative disaster chain network of overhead line failures and forest fires is built based on complex network theory, and the effect of the coupling induction of forest fires and overhead line failures on the formation mechanism of the disaster chain is investigated. First, indicators such as degree centrality and closeness centrality are calculated to evaluate the role and influence degree of each disaster node in the disaster chain network from multiple perspectives. Subsequently, the key nodes in the failure and secondary and derivative disaster chains between overhead lines and forest fires are determined. Second, the transmission probability of each evolution path in the disaster chain is used as the assessment criterion, and the Jaccard index is employed to identify the key evolution paths.

First, 92 related accident cases are analyzed, and experts are consulted to determine the inducing relationships among various disaster nodes. Based on this, a disaster chain evolution model is constructed to investigate the failure and secondary and derivative accident chains of the overhead lines and forest fires. This model has 21 disaster nodes, 46 edges, and 60 disaster evolution paths. Four indicators are calculated: degree centrality, closeness centrality, betweenness centrality, and disaster node hub count. The top five disaster nodes are forest fires, casualties, overhead line failure, forest resource destruction, and toxic gas leakage. The transmission probabilities of different disaster evolution paths are calculated based on the frequency of the disaster chain nodes in statistics and the Jaccard index. To confirm the validity of the model and its conclusions, a sensitivity analysis is conducted at the node of overhead line failures, which verifies the relevance of risk management for overhead lines in reducing the risk of the disaster chain.

Based on theory of chain-cutting disaster mitigation, how to cut off the evolution paths of the disaster chain or the control key disaster nodes and how to prevent the occurrence of secondary and derivative accidents are clarified in this paper to provide decision support for the actual prevention and control of forest fires and the operation and maintenance of forest power grids.