Improved Functional Dependency Method to Break-Point Determination for Protective System Coordination

Modern power systems have a multi-loop structure. Coordination of protective relays in these networks is a tedious and time consuming task. The most complicated part of this process is determination of Break-Point Set, BPS, to start coordination procedure. As BPS is not unique, it is desirable to determine a BPS with a minimum or near to minimum, minimal, number of members. This paper presents an improved functional dependency based method. A reduction method is presented to reduce the network, which leads to decrease in the problem dimension and computational burden. This method has the capability of considering the three-end branches such as three-terminal transmission lines and three-winding transformers, which graph theory based methods can not handle them.