On implementing a spectral clustering controlled islanding algorithm in real power systems

Wide area blackouts can be caused by unexpected fault scenarios, in particular protection maloperation, or simultaneous low probability events, which as such might lead to e.g., un-damped electromechanical oscillations. A Spectral Clustering Controlled Islanding (SCCI) method to find a suitable islanding solution for preventing such events was previously proposed and tested using different IEEE test networks. The sole constraint applied to this solution was related to generator coherency. The method demonstrated promising results when it was implemented on these IEEE test networks. The SCCI method was later tested using a simplified Cypriot Network and the Polish Network. The results achieved when implementing the SCCI method on actual power systems highlight practical issues that were not previously considered and require to be addressed when using it. Therefore, this paper presents a robust SCCI method. An outlier problem which affects the quality of clustering and a problem with the computational efficiency of the algorithm (when dealing with systems larger than 500 nodes) are presented and analyzed in this paper. To improve the clustering quality, a more robust clustering algorithm, k-medoids, is used to cluster all nodes in the solution subspace and to find the islanding solution.