Preventive Mitigation Strategy for the Hidden N-k Line Contingencies in Power Systems

In this paper, we address the risk of hidden N-k line contingencies in power systems by proposing a preventive mitigation strategy to mitigate these hidden contingencies. The strategy comprises a screening model, an evaluation model, and a mitigation cut generating mechanism. Using this strategy, we first screen out the high-risk hidden N-k line contingencies using the screening model, and then mitigate them by iteratively reducing their hidden probabilities assessed in the evaluation model. This is achieved by incorporating mitigation cuts into an enhanced security constrained economic dispatch module, while taking into consideration both reliability and economic criteria. This mitigation strategy can be employed as a preventive action by the system operators. The simulations on the IEEE 118-bus system demonstrate that the proposed approach can reduce the hidden probabilities of these high-risk contingencies below a given threshold with a reasonable increase in the generation cost, and, thus, verify the approach as an effective tool to address the risk of these contingencies.