Attenuation of the Harmonics and Compensation of Reactive Power by Active Filtering

M. Adli, O. Ouahab, and A. Ziane-Khodja (Algeria)


3. FILTERINGnonlinear loads, reactive power, static inverters, harmonics, active filtering, A simple solution would be the filtering which consists in "trapping" the harmonic currents in LC circuits in tune on the rows of harmonics to be filtered. A filter can thus include a series of "steps" which correspond to a row of harmonic. Rows 5 and 7 are usually the most filtered because they are the most disturbing. The installation of a filter can be considered for one load or for whole of lo


The improvement of the intrinsic parameters of the electro-energy systems and the improvement of the devices of power electronics which can influence each type of adjustment are a major concern in the analysis and the identification of several criteria of the evaluation of the quality of distributed energy. This quality is dependent on the fed loads which are in many cases nonlinear because of the thorough use of the static inverters of power electronics. This increased use is due to the industrial development of automation. The static inverters do not absorb sinusoidal currents and generally consume reactive power. These two phenomena produce some disturbances like the dysfunction of the equipment in the worst cases. In this article, our interest is the attenuation of these two phenomena by the method of active filtering. We create antagonistic currents to the disturbing currents in order to annihilate them. It is necessary to choose a structure proven as being slightly polluting on the one hand and a converter equipped with a suitable control making it possible to relieve the structure of the converter on the other hand. The increase of the index of pulsation using a rectifier with 12 diodes called “twelve-phase” bridge which one is carried out by connecting two Grätz bridge rectifiers in parallel to fed with the common continuous bus. The disadvantage of this solution it is the recourse to a transformer with two of different couplings. The reinforcement of the short-circuit power and the reduction in the total network impedance upstream of a nonlinear load make it possible to reduce the voltage drop created by the harmonics of current, and to decrease the harmonic rate of distortion in the voltage at the connection point. On the other hand, the harmonic currents are not attenuated [2].

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