A Comprehensive Assessment of Fundamental Overcurrent Relay Operation Optimization Function and Its Constraints

Abstract

The optimization of overcurrent relays’ operation is a topic associated with protection coordination of distribution networks. Usually, this refers to medium-voltage networks, since they are protected by numerical relay devices, as opposed to low-voltage networks, where utility operators allocate fuses. Correct setting of relays and optimal coordination is becoming a serious challenge to Distribution Network Operators around the world, since their networks’ passive operation has been greatly altered in the past two decades. Distributed generation units, a growing liberalized electricity market and more stringent legislation for distribution network planning and operation by state regulatory bodies have all indirectly affected the evolving of protection philosophy for distribution networks. In this paper the traditional optimization problem of overcurrent relay operation will be addressed and critically examined from both a theoretical and practical point of view. Optimization function, constraints and relay parameters will all be observed and compared with solutions used in distribution networks, and their modifications and improvements will be proposed and elaborated in detail.

Optimal coordination of directional over current relays for distribution systems using hybrid GWO-CSA

“…However, the time it takes for them to operate should not be excessive. This places a constraint on the operating time as shown in (3).…”

“…A variety of methods for OCR coordination have been suggested. Three categories can be made out of these techniques: optimization, topological analysis, and trial-and-error [3]. However, in the first two classes' Int J Pow Elec & Dri Syst ISSN: 2088-8694  Optimal coordination of directional over current relays for … (Arathi Pothakanahalli Bheemasenarao) 1277 solutions, the plug multiplier setting (PMS) or pickup setting (PS) and time multiplier setting (TMS) were manually determined using expert knowledge or analytical computation to ensure the optimal relay coordination.…”

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“…It should be above the largest possible load current and below the minimum short-circuit current, with a safety margin. Therefore, the main objective of the coordination problem is to find the optimal time multiplier setting and plug setting with a minimum operating time of DOCRs and under different network configurations and conditions [23], [24].…”