Design and Implementation of Overcurrent Protection Relay

Protective relays have been designed with different technologies resulting in electromechanical, solid-state, and numerical devices. Speed and reliability are the two most important characteristics of a protective relay. Other capabilities such as monitoring and recording are supposed to be of secondary priority. The new technology using combination of field-programmable analog arrays (FPAAs) and digital technologies seems to be a breakthrough and has the potential to provide better performance than the present-day numerical relays. The use of FPAAs for designing and implementing overcurrent relay is investigated. The modeling and simulation of a protected system using Matlab are described. Hardware implementation using FPAAs is described. The practical test for different types of fault conditions is presented. The practical results show the ability of the new protection to response to the steady-state fault condition fastly and also can obtain different types of Time–Current characteristics with high accuracy. Also two types of characteristics Inverse Definite Minimum Time type IDMT type and very-inverse type are implemented, the protection system is tested in a fault of line-to-line type and the results show the ability to discriminate the fault condition and isolate the faulted section only, the remaining network can operate normally.