A device has been developed to measure the harmonic impedances of power network by using harmonic voltage and current increments at the point of common coupling between the network and a disturbing load. The key problem in the implementation of the method is the synchronization of phasors sampled asynchronously and at different times. This kind of synchronization is linked to the frequency measurement. A small error in the frequency will cause a great deviation of the impedance measurement. A formulation is given here to evaluate the error on the impedance in each individual measurement (event), and a statistical method is proposed to achieve a relatively high accuracy in the source impedance estimation. Laboratory and field tests results are both discussed as well as verified with the harmonic emission level estimation of the disturbing load.SCOPUS: cp.pinfo:eu-repo/semantics/publishe

Harmonic impedance is a key parameter for filter design and assessment of harmonic emission level. Till present, there is no simple and convenient measurement method and instrument for determining harmonic impedance. Due to lack of basic system parameters, error in harmonic impedance calculation is great. This paper investigates a harmonic impedance measurement method named increments in harmonic voltage and current. Major errors source from power frequency shift and phase angle synchronization for signals at different sampling windows is analyzed and error evaluation method is provided, On which, “dual synchronization” method and its implementation is proposed. The effectiveness of the proposed method is confirmed by experiment. The proposed method provided a simple and convenient approach for harmonic impedance measurement.