Accurate Voltage Phasor Measurement for Electric Power Transmission Line Protection Using Current Sensor

Accurate voltage phasor measurement is important for differ-ent applications in electric power systems including protection, control, and monitoring. At power transmission level, the transient response of the capacitor voltage transformer is a concern for the phasor based protection applications. This letter presents an accurate voltage phasor measurement technique at an electric bus during transient using the current through the capacitor voltage transformer. The numerical integration of current is multiplied with current transformer ratio and with the reciprocal of equivalent capacitance of the capacitor voltage transformer to obtain the accurate voltage during transient. The dependency of the obtained voltage accuracy on the current measurement error is also analyzed. The performance of the proposed technique for phasor estimation used in directional and distance protections during capacitor voltage transformer transient is demonstrated and found to be accurate. The performance of the proposed method is free from the capacitor voltage transformer topologies and operating conditions of electric power systems.