A Graph-Based Framework for N-k Contingency Analysis of Substation Maintenance Isolation

Verifying the electrical safety of maintenance work zones in substations against multiple equipment failures (N-k contingencies) is a computationally intensive challenge. Brute-force methods become impractical as the complexity of the contingency analysis increases. This paper introduces an optimized algorithm that leverages topological pruning to dramatically reduce the computational search space. By first identifying a small, critical subset of failure-prone components that can physically affect the work zone, the algorithm bypasses the need to check thousands of irrelevant contingencies. The methodology was validated on a benchmark 220kV substation for multiple resilience levels. The results demonstrate performance gains that grow exponentially with complexity: the optimized method was up to 94x faster for N-3 analysis, completing the most complex check in under one second. The findings confirm that this approach transforms high-level contingency analysis from a prohibitively slow task into a feasible, near real-time operation.