The influence of power electronics equipment, generators of synchrounous and asynchrounous harmonics (high frequency noise) on the electricity network and its drawbacks for the customers are well known. Solutions do exist. On the network side, it is possible to configure it in a way that makes the internal impedance at the connection point low (fault current at any point higher than or equal to ten times the rated current). A judicious choice of the coupling of the power transformers will help too. On the side of power electronics equipment the situation is very complicated because it results from non-linear effects and from dynamic operating conditions. This leads into the creation and the superposition of harmonics being whole multiples of the supply frequency, harmonics not being whole multiples of the supply frequency, subharmonics, i.e. harmonics lower than rated network frequency, as well as d.c. components. The reduction of the harmonic level or the suppression of harmonic orders can theoretically be achieved by a due control technique but the end result depends strongly of the converter structure and the commutation speed of the semiconductor components. Furthermore the situation is made more difficult because of the associate L-C networks for protection purpose. One last possibility, and for many years it was the only possible one, is the interposition of low pass filter, and, or, more costly band stop filters; the last ones should be more and more considered as an emergency solution. We can reflect on the future evolution of these two fields - electricity distribution and power electronics - both having a major advantage in living together and developping in a harmonious way. This is what this paper is all about.
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