Modelling of Logic Circuit for Enabling High Speed Auto Reclosure of High Voltage System

Auto Reclosure (AR) function is an integral feature of high voltage transmission line for maintaining stability, availability and reliability. For the execution of successful AR function, modern numerical relays are used which consist of programmable logic involving series of binary input and output iterations. The primary condition for successful AR function is the clearance of transient faults. However along with the clearance of transient fault, the performance of AR function also depends upon the proper execution of programmable logics in the relay. In this paper a model has been developed in SIMULINK for formulation of a logical circuit consisting of binary input, binary output and logic gates. The output of the logical circuit leads to development of two unique blocks which consists of all the logical iterations for successful auto reclosure function during transient fault and auto reclose lock out function during persistent faults respectively. The model has been verified with data obtained from an actual fault occurred in a 400KV system of POWERGRID North Eastern Regional Transmission System and the performance has been validated. This paper will help the utilities to use the proposed blocks directly in the numeric relay for successful auto reclosure and lock out function respectively.