Numerical Quadrilateral Distance Relay

The paper presents a new technique for implementation of numerical quadrilateral distance relay. The characteristic of the numerical quadrilateral distance relay is realized by measuring the instantaneous values of the voltage and current based on sampling principle. For this purpose an Advantech data acquisition device is used. The system voltage and current is fed to this device from PT and CT respectively. This device samples the input signals and feed it to the computer. Software in Visual Basic is used to program this device as well as to calculate the resistance& reactance from the measured values of voltage and current. The calculated values are compared with a predetermined set of conditions. These conditions are set according to the quadrilateral distance relay characteristic. Finally, depending on the compared results, trip signal will be generated by software for tripping the circuit breaker.