Topologies and control of active filters for flicker compensation

The paper deals with the analysis of topologies and control strategies of active filters (AF) for voltage flicker compensation. The strategies based on parallel and series active filters, both working with the reactive power compensation (without an energy storage device) have been analyzed and compared. The basic operational characteristics for the parameters of a real distribution power system with an arc furnace and a static VAr compensator have been calculated to promote the installation of an active filter for the mitigation of the voltage fluctuation. The control strategies of the active filters have been analyzed in the frequency domain as well. Neither the parallel AF nor the series AF, both working with the reactive power compensation and without the static VAr compensator (SVC), do not represent an appropriate solution in the case of the study: the parallel AF would need a high power rating, while the series AF has a too narrow working area. The combined application of the current SVC and the AF is a beneficial solution, the series AF being preferred to the parallel one for a substantial reduction of the AF power rating