Nodal Reliability Evaluation for Power Grids Based on Modified N - k Security Constraints

The security criterion of power grids has been upgraded from $N-1$ to $N-k$ due to the large scale integration of renewable energy, frequent occurrence of natural hazards, and occasional random or intentional attacks Nevertheless, the growth of k will lead to explosion in resource consumption. Furthermore, buses in power grids are distinctive, only a few key nodes require an enhancement in reliability. Thus, the nodal reliability evaluation metric is demand for further investigation. In order to reflect the real fault severity that the buses can withstand, the definition of nodal $N-k$ security criterion is proposed in this paper, which emphasizes the differences between buses and decouples original security constraints from system level to individual node. Accordingly, three nodal reliability indicators are developed, where the performance comparison and rationality validation are demonstrated on two standard case studies, i.e., IEEE 24-bus and 39-bus systems.