Protection co-ordination: determination of the break point set

Modern power system networks are often multiloop structured. Co-ordinated setting of overcurrent and distance protective relays in such networks is tedious and time consuming. The complicated part of this problem is the determination of a proper minimum set of relays, the so-called minimum break-point set (BPS), to start the co-ordination procedure. The paper presents a new graph-theoretical method to determine a near-to-minimum or a minimum BPS. Using the lemmas of this method, the determination of a minimum BPS can be reduced and decomposed into subproblems. Owing to the efficiency of these lemmas, the presented method quickly achieves the result, even for large networks. Moreover, due to the simplicity of the method, it can be manually applied to the graph of each network. Since the presented lemmas are general, they can be applied to improve any method dealing with BPS determination.