Contributions on harmonic impedance monitoring in smart grids using virtual instruments

Harmonic impedance is an efficient instrument to assess the state of a harmonic polluted grid, to anticipate unfavorable operating regimes and the selection of means of intervention. The monitoring and then use that information in expert systems for optimizing the basic operating regimes will be attributes of smart grids of the future. This article presents a virtual instrument built using National Instruments technology, which was designed to determine by direct measurement of harmonic impedance seen in a section of a three-phase electricity distribution network. The method of determination is the well known “method of variations”, which is applied in the case when the two stationary operating regimes of the network are considered: before and after the switching of a step of regular capacitor bank, installed in the network for the power factor improvement or for the voltage control.