Accurate Impedance Measurement Technology for Power Line Communication Considering Noise Interference

ABSTRACT The impedance of power line channels is related to various factors such as frequency, time, connection location, load type, and power grid structure. The impedance mismatch will reduce the coupling efficiency and transmission efficiency of signals, and seriously affect the quality of power line communication. Therefore, accurate measurement of power line channel impedance and analysis of impedance characteristics are of great significance for improving the reliability of power line communication. In this paper, an improved ratio method considering the noise interference is proposed. In the method, the original generation method of sweep frequency signals is changed to one‐time multi frequency and variable amplitude injection signals. Based on real‐time signal processing technology, the voltage information at all tested frequency points is measured at once, including amplitude and phase. Through digital signal processing technology, the influence of noise is weakened, and the impedance amplitude and phase of all tested frequency points are accurately calculated. By the method, the requirements of the measurement circuit are simplified and the frequency range of impedance measurement is expanded to 100 kHz to 12 MHz. Finally, the impedance characteristics on the concentrator side and the user meter side are measured, laying the foundation for impedance matching design and improving power line communication quality.