Comparison of time-domain and frequency-domain control schemes for shunt active filters

The proliferation of power electronic loads with a non-linear relationship between voltages and currents has led to increasing current and voltage distortion in distribution systems. With the development of active filters based on pulse-width modulation (PWM) converters, an effective tool to improve voltage quality is available. In this paper the characteristics of two control algorithms for the control of shunt active filters and their practical implementation are compared. The first one is based on the so-called Fryze-Buchholz-Depenbrock (FBD) method which calculates and compensates the non-active load currents using time-domain algorithm such that the supply network provides purely active currents. The other one identifies and compensates preselected harmonic components of the line currents using a frequency detection algorithm. This approach reduces the power rating of the compensator.