Directional Over-current Relay Coordination using Improved Mathematical Formulation and Soft Computing Technique

Abstract

Relay coordination is one of the most crucial process in the field of protection for power systems. In order to ensure a proper and healthy system protection for a particular system should be done carefully. In this the optimum coordination for directional over-current relay has been done. The objective is to minimize the value for relay settings along with maintaining the coordination constraints in the system. For the above five objective functions have been developed and being compared on the basis of their operating time for the relay settings with certain weight assigned to each objective function in order obtain optimum relay coordination. These objective functions are evaluated and then a new objective function i.e. a proposed objective function (POF) is being developed in order to improve the previous objective functions. Finally the coordination has been formulated by the use of soft computing technique and the outcome is compared with all the objective functions on the basis of operating time for both primary as well as back-up relay along with maintaining the value of discrimination time up-to a prescribed followed by satisfying the coordination constraints of the system.