Influence of the grid topology on the grid access impedance in the 20-500 kHz frequency range

This paper aims at evaluating the influence of the network topology on the grid impedance in the 20-500 kHz frequency band by performing measurements in reconstructed facilities. The analysis leads to conclude that the measured impedances do not match the characteristics (spectral pattern and amplitude) of the reference impedance defined in the CISPR 16-1-2 standard for any of the network topologies configured. The results reveal that the influence of the topology is less significant in the 150-500 kHz frequency band (maximum variations of ± 6.5 Ω in modulus and ± 0.7 rad in phase) than in the 20-150 kHz frequency range, where variations ranging from -106.6 Ω to 118.8 Ω in modulus and -2.5 rad to 2.1 rad in phase are reported.