Harmonic Synchrophasors Measurement Algorithms with Embedded Compensation of Voltage Transformer Frequency Response

The widespread diffusion of nonlinear power electronics-based devices in distribution grids has raised the interest toward power quality monitoring. In this respect, the estimation of synchronized harmonic phasors would enable the employment of algorithms that allow identifying the sources of harmonic disturbances, which, until now, have only been tested through numerical simulations or implemented on small-scale. However, the impact of the uncertainty due to the employed voltage transformers (VTs) and to the other devices that compose the measurement chain has to be analyzed. In this framework, the present article proposes a class of harmonic synchrophasor estimation algorithms that allows compensating the frequency response function of the instrument transformer. The technique has been tested and validated under realistic conditions considering an inductive VT. Experimental results highlight its effectiveness, especially when taking into account its ease of implementation. The black-box approach allows abstracting from the operating principle of the VT.