Optimal coordination of directional overcurrent relays (DOCRs) is a highly constrained and nonlinear optimization problem. The operating time of each relay depends on two independent variables called plug setting and time multiplier setting. As the network becomes larger and more complex, the number of relays will increase and, thus, finding the optimal solution becomes very hard. In this paper, a new population-based evolutionary algorithm called biogeography-based optimization (BBO) is proposed and the performance of ten types of constraint-handling techniques is evaluated. In addition, a new hybrid BBO with linear programming (BBO-LP) is proposed to enhance the performance of the conventional BBO algorithm. The performance of the proposed BBO-based algorithms is evaluated by using five test systems. The results show the effectiveness and superiority of the proposed algorithms compared with the performance of the other optimization methods presented in the literature.

Optimal Coordination of Directional Overcurrent Relays Using Biogeography-Based Optimization Algorithms

Microgrid clustering architectures

Optimal Overcurrent Relay Coordination: A Review

This paper presents genetic algorithm (GA) method for coordination of overcurrent (OC) relays. The OC relays are the major protection devices in a distribution system. OC relay is usually employed as backup protection. But in some situations it may be the only protection provided. To reduce the power outages, mal-operation of the backup relays should be avoided, and therefore, OC relay coordination in power distribution network is a major concern of protection engineer. The OC relay coordination in ring fed distribution networks is a highly constrained optimization problem. The purpose is to find an optimum relay setting to minimize the time of operation of relays and at the same time, to avoid the mal-operation of relays. This paper presents GA technique for optimum coordination of OC relays in a ring fed distribution system. Constraints are incorporated in the fitness function making use of the penalty method. Computer programs (using MATLAB) have been developed for optimum coordination of OC relays using GA technique.

Optimum coordination of overcurrent relays in distribution system using genetic algorithm

This article presents the simplex method for optimum time coordination of directional overcurrent relays. The main contribution of this article is the application of the simplex method in spite of the inherent unsuitability of the problem. This is achieved by applying the simplex algorithm to the dual of the problem. Furthermore, there are reductions in the number of calculations and memory requirement, as the artificial variables need not be introduced. A comparison with other variants of the simplex algorithm and the genetic algorithm is also presented. It has been shown that the proposed method is applicable for finding the optimum coordination, even when a variety of overcurrent relays is present in the system.

Optimum Coordination of Overcurrent Relay Timing Using Simplex Method

They may occupy different angular positions, but all machines rotate at the same electrical speed. This close knitting implies an embedded interaction of generators through the transmission network which is governed by the differential and algebraic equations of the apparatus and interconnects. This aspect is referred to as the system behaviour. This system has to be protected from abnormalities which is the task of protection system.

Y. G. Paithankar

Papers

Fundamentals of Power System Protection