A shunt active power filter: development of properties

Numerous types of shunt active power filters have been proposed in many papers. The classification of these filters depends on various points of view. However, every type of a shunt active filter, which compensates non-active component of load current, irrespective of the method used to detect this component and control strategies of the filter, should keep supply source current equal to active current of a load-and-filter circuit. This goal can be achieved in many ways, using various structures of active filters. But different realizations of filters cause differences in their properties. This paper, which is meant to serve as a review and synthesis of earlier work, shows some possibilities of forming of single-phase shunt active filter behaviour. The following active filter properties are discussed: operation with an immediate reaction in the supplying source branch to a load current change, and with the reaction only once in each supplying source cycle; regulation by the filter of the non-active current component of fundamental frequency; active filtering and simultaneous feeding of DC load with stabilizing DC voltage; operation with stabilization of supplying source current amplitude; reducing filter switching frequency; and reducing current distortions in the supplying source branch. All the waveforms presented were produced using a computer simulation method.