Improved Voltage Harmonic Control for Shunt Active Power Filters Using Multiple Reference Frames

A new control method for shunt active power filters based only on supply voltage detection is proposed in this paper. A suitable harmonic extraction structure is designed to calculate the active filter compensating current in the d-q reference frames rotating at different harmonic frequencies using line voltage measurements. Every harmonic frame is decoupled from the others so to avoid interactions among the different control loops and to make possible to study the whole system through the superposition principle. The effectiveness of this method is proved by computer simulation using Matlab/Simulink.