Design and implementation of quadrilateral and elliptical relay on TLS using NRDE

Distance relay scheme is widely used for the protection of transmission lines. It has many characteristics such as Impedance, Reactance, MHO and Quadrilateral characteristics. Quadrilateral characteristics provide better protection for Transmission line as compared to other characteristics. This paper presents the development of quadrilateral and elliptical relay characteristics in Numerical Relay Development Environment (NRDE) using MPLAB software and its implementation on Transmission Line Simulator (TLS). For this a hardware interface between TLS and NRDE is designed and developed using Proteus. Characteristics of the relay are realized by measuring the values of voltage and current. The analog voltage and current signals from TLS are given to NRDE through hardware interface. MPLAB software is used to program the relay as well as to calculate the impedance from the measured values of voltage and current. This calculated impedance is then used to calculate the values of resistance and reactance, which are then compared with the predetermined set of conditions. These conditions are set according to the desired relay characteristic. Trip signal is generated by the software, depending on the predetermined conditions. With the help of whole setup quadrilateral and elliptical relay algorithms are developed and tested successfully.