Network Impedance Measurements for Three-phase High-voltage Power Systems

The network impedance of power systems is an important quantity for many power system calculations. This paper presents a novel method for measuring network impedances of high-voltage (110 kV) power systems by injecting line-to-line test signals. The injected test signals are generated by a medium-frequency converter and fed to grid by a station transformer. During the measurement, we only assess the fundamental signal in order to ensure the measurement accuracy. As the transfer ratio of voltage and current transducers is questionable, we calibrate the total measurement system. The field tests show that the proposed method is suitable for measuring network impedances of high-voltage power systems.