Analysing two control methods of shunt active filters for unbalanced load

Abstract

A three-phase shunt active filter is used for current and/or voltage unbalance compensation. Two control schemes with two different theory, instantaneous power theory and Generalized Fryze are considered to compensate the unbalance of current, voltage, or both that are due to the unbalanced load. The compensation results of the different control schemes in unbalance case are simulated and results are shown here. Different compensation objectives can be achieved, i.e., balanced and unity power factor source current, balanced and regulated voltage, or both, by choosing appropriate control schemes by using Instantaneous Power theory. In the case of Generalized Fryze it is seen that the current compensated by means of the generalized Fryze currents method makes the compensated line current proportional to the corresponding phase voltage, that is, they have the same waveform and behave like a “pure resistive” load