Is It Enough to just Rely on Near-End, Middle, and Far-End Points to get Feasible Relay Coordination?

Abstract

Power system protection is a very crucial branch of electric power engineering. This branch is divided into many sub-branches, such as: protection design, relaying and algorithms, fault location, and recently optimal relay coordination (ORC). Since the end of the eighties of the last century, ORC becomes one of the hot topics covered in the literature. Many analytical and numerical techniques have been presented as effective tools to solve this highly constrained, nonlinear, non-convex mixed-integer optimization problem. However, these optimizers are built based on a hypothesis that feasible optimal solutions can be guaranteed if the discrimination margin between the operating times of each primary and backup (P/B) relay pair is satisfied at some three-phase fault points specified on each line. This paper tries to study different design criteria, used during solving ORC problems, to answer the main question raised in the title.