Measurement and Analysis of the Low Voltage Network Impedance in the Supraharmonic Range

The supraharmonic distortion levels and their propagation in low voltage networks are determined by the supraharmonic- or frequency-dependent network impedance (FDNI). Knowledge of the FDNI is limited and mainly based on assumptions, measurements to determine the actual values are uncommon and not readily available. In this research, a current injection-based measurement system is developed to measure the impedance from 10 to 150 kHz at low voltage installations. The measurement system is validated using lab measurements and a measurement campaign at different residential- and office installations is carried out to quantify the network impedance. It is found that both the amplitude of the impedance and the resonant frequencies are highly influenced by devices connected locally. The results provide typical ranges of the FDNI in low-voltage installations and contribute to the assessment of supraharmonic impact and propagation.