Estratégia seletiva de supressão de correntes harmônicas em sistemas trifásicos a três e quatro fios aplicada a um filtro ativo de potência paralelo

Abstract

This work proposes to use a selective strategy to generate the compensation reference currents of the Shunt Active Power Filter (SAPF), which allows to select what components composing load current should be synthesized by means of the filter. The strategy is composed by seven SRF-based algorithms and it will be applied to a SAPF, which uses the Four-Legs inverter. In order to explore the potentialities of SRF method, the strategy defines seven operation modes for the SAPF used in four-wire three-phase systems. The different operation modes allow: total or selective harmonic suppression; to compensate or not to compensate the reactive power; to compensate or not to compensate the zero-sequence and/or negative-sequence fundamental load currents. The different algorithms are derivate from the SRF method considering positive-sequence, negative-sequence and zero-sequence symmetrical components. It is noteworthy that a new technique to detect the negativesequence and zero-sequence fundamental components related to reactive power is formulated. In view of applying the strategy to generate the compensation reference currents, it is carried out the modelling of the SAPF in coordinates, as well as in 0 coordinates. The resulting model for the 0 coordinates is used in this work because, by means of this one, it is possible to obtain three decoupled systems in each coordinate. Additionally, the duty cycle considered in the space vector modulation used to drive the power switches of the PWM converter is too treated in 0 coordinates. Using the 0 model, the compensation current controllers and the dc-bus controller are all projected in continuous time. After this, the controllers are discretized and embedded in a digital signal processor. In this way, by means of numerical simulations and experimental tests the strategy used to generate the compensation reference currents is evaluated, allowing to validate the theoretical studies carried out.