| Abstract |
Nowadays, four-wire shunt active power filters are used to compensate current harmonics, reactive
power and unbalanced currents. To control these, it is necessary to obtain active filter reference
currents starting from load currents. There are various ways to obtain these reference currents [1]-[5].
In this work a UPF-SFR control method [8] for a four-wire shunt active filter is presented. Depending
on the position occupied by a three channel analogical switch, this method allows two different ways
of operating. In the first, the set formed by the non-linear load and the filter behaves like a resistor
(UPF, unity power factor). In the second the line currents are perfectly sinusoidal (SRF, synchronous
reference frame). The voltage THD according to [7] will impose the change between both ways of
operating. The filter currents are controlled by a space vector current controller [9] based on three
level hysteresis comparators using Scott’s transformation. The system has been simulated for both
unbalanced and non-sinusoidal load currents and AC voltages showing waveforms of the line currents
in both ways of operating. The non-linear load is composed of three single-phase diode-bridge
rectifiers with both a resistance and a filter capacitor each one. |
