Dual synchronization incremental method for harmonic impedance measurement

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.