Controlled Islanding Based on the Coherency of Generators and Minimum Electrical Distance

Inter-area oscillations and cascading failures are the most significant threats to power system security. In case of unstable inter-area oscillation or progressive cascading failure, the system will be faced uncontrolled islanding. The establishment of uncontrolled islands with a deficiency in load-generation balance is the main reason for system blackout. In this respect, for reducing the risk of blackout, controlled islanding has been considered as a preventive strategy. In this paper, based on the coherency and nearest electrical distances between loads and coherent groups of generators, a new algorithm for applying the strategy of controlled islanding is proposed. In this method, first based on the correlation coefficients between generators and the DBSCAN clustering algorithm, coherent generators as the main core for controlled islands are identified. Then by using mixed-integer linear-programming around each coherent group, the sub-networks are established. Then, non-linear programming is used to construct the stable sub-networks associated with islands satisfying load-generation balance, voltage limits, and transmission limits. The proposed scheme is implemented on the IEEE 39-bus system as a small system and Iran power network as a large-scale realistic power system. The results show the ability of the proposed method for implementation in a real power system.