Optimal choice of the number of even harmonics demodulated from the excitation current of a sensor for precise dc voltage component detection in low voltage distributive grid as a strategy for suppression of the systematic error due to the grid voltage fluctuation

This paper addresses the problem of suppression of a systematic measurement error during the detection of a parasitic DC voltage component, superimposed to an AC voltage. As a sensor the toroidal transformer is employed. The origin of the error under scope is the fluctuation of ac voltage around its rated value. Two groups of experiments, based on the new even harmonics method for precise DC voltage offset detection, are performed, analyzed and results compared. The first one successfully resolves detection of parasitic DC components in low voltage distributive grids. The second one is focused on the DC offset voltage detection of the Fluke 6100A Electrical Power Standard. A comparative analysis of the influence of different sets of the even harmonics of transformer excitation current on error propagation, give the consistent results.