Browsing by Author "Moran, LA"

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    A fault protection scheme for series active power filters
    (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1999) Moran, LA; Pastorini, I; Dixon, J; Wallace, R
    A protection scheme for series active power filters is presented and analyzed in this paper. The proposed scheme protects series active power filters when short-circuit faults occur in the power distribution system. The principal protection element is a varistor, which is connected in parallel to the secondary of each current transformer. The current transformers used to connect in series the active power filter present a low-magnetic saturation characteristic increasing current ratio error when high currents circulate through the primary winding, thus generating lower secondary currents. In this way, the power dissipated by the varistors is significantly reduced. After a few cycles of short-circuit currents flowing through the varistor, the gating signals applied to the active power filter switches are removed and the pulsewidth-modulation (PWM) voltage-source inverter (VSI) is short circuited through a couple of antiparallel thyristors.
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    A series active power filter based on a sinusoidal current-controlled voltage-source inverter
    (1997) Dixon, JW; Venegas, G; Moran, LA
    A series active power filter working as a sinusoidal current source, in phase with the mains voltage, has been developed and tested. The amplitude of the fundamental current in the series filter is controlled through the error signal generated between the load voltage and a preestablished reference. The control allows an effective correction of power factor, harmonic distortion, and load voltage regulation. Compared with previous methods of control developed for series active filters, this method is simpler to implement, because it is only required to generate a sinusoidal current, in phase with the mains voltage, the amplitude of which is controlled through the error in the load voltage. The proposed system has been studied analytically and tested using computer simulations and experiments. In the experiments, it has been verified that the filter keeps the line current almost sinusoidal and in phase with the line voltage supply. It also responds very fast under sudden changes in the load conditions, reaching its steady state in about two cycles of the fundamental.