Harmonic Impedance Identification of Low-Voltage Consumers

Inhalt:
In this contribution the harmonic impedance of typical low-voltage consumers are measured and analyzed. Two different measurement devices have been used to identify the harmonic impedance under operation conditions, the commercial device EWS 120 and the ONIS-600V, which has been developed at the Helmut-Schmidt-University. Both devices were originally designed for frequency-dependent impedance identification of low-voltage grid connection points. Yet, with a small modification of the measurement setup, it is possible to determine the harmonic impedance of loads with these devices. Loads with linear characteristics can be identified with high precision. However, non-linear consumers distort the impedance measurement and have non-linear impedance characteristics. To identify their harmonic impedance requires special correlation techniques which are presented and applied in this paper.