Performance and suitability assessment of controlled islanding methods for online WAMPAC application

Controlled islanding can be used as an efficient action to prevent catastrophic blackouts. It splits a power system into a group of stable islands, according to an islanding solution that has been generated using an islanding method. A detailed understanding of these methods is a sound basis for the development of feasible controlled islanding methods for future networks. In this paper three methods (a) Ordered Binary Decision Diagram, (b) Weak Connection and (c) Spectral Clustering, are selected as typical islanding methods. The paper presents an analysis of their essential differences and their potential suitability for use as part of a practical implementation of controlled islanding. They are critically assessed and contrasted in terms of the objective function, graph model, solving algorithm and time complexity. The key difference between these methods is the nature of the objective function used: minimal power imbalance, minimal dynamic coupling or minimal power-flow disruption. A different objective function may require a different graph model and a different solution algorithm, which may result in the islanding methods having different time complexities and produce different islanding boundaries for the same network. Each method is applied to the IEEE 118-bus system to explore their strengths and weaknesses. Criteria for the selection of a suitable, practical method are discussed, as is the feasibility of Controlled Islanding as a WAMPAC application.