Online Monitoring of Transmission Line Parameters Using LabView

In power system, the power flow in a transmission line is calculated based on the designed line impedance which is assumed to be constant. But, practically the line impedance changes due to the harmonics, frequency change and many more environmental factors. This change in the line impedance makes the power flow calculations wrong. There should be monitored mechanism to calculate the line impedance for accurate analysis of power flow which helps in improving the reliability and security of the power system. In this paper, the monitoring technique is developed using Fast Fourier transform which provides the fundamental frequency information for voltage and current from which the line impedance is calculated. The proposed method is tested on a scaled down laboratory model of 300km transmission line. The voltage and current signals are sampled using a simultaneous sampling DAQ. These sampled signals are given to the FFT algorithm which is developed in the LABVIEW software. From the obtained phasor values, the line parameters are calculated and compared with other measurement techniques and designed values. The change in line parameters values due to change in frequency is not observed by direct LCR measurement and indirect offline measurement and is possible through the proposed method.