Identifying Plausible Harmful N-K Contingencies: A Practical Approach Based on Dynamic Simulations

This paper presents a practical search algorithm using detailed dynamic simulations to identify plausible harmful N-k contingency sequences. Starting from an initial list of contingencies, progressively more severe contingency sequences are investigated. For that purpose, components, which violated conservative protection limits during a N-k contingency simulation are identified and considered as candidate k+1-th contingencies, since these could be tripped due to a hidden failure. This approach takes into account cascading events, such as over-or under-speed generator tripping, which are considered to be part of the system response. The implementation of the proposed algorithm into a parallel computing environment and its performance are demonstrated on the IEEE Nordic test system.