A novel control scheme in 2-phase unified power quality conditioner

Improving power quality for sensitive load by a unified power quality conditioner (UPQC) in a distributed generation system is presented in this paper. The power balance of this UPQC, consisting of back-to-back connected series and shunt active filters, is analyzed. Based on the analysis a novel control scheme is established in 2-phase synchronous rotating d-q frame (SRF). In this control scheme the series AF is controlled as a current source and makes the input current sinusoidal, while the shunt AF is controlled as a voltage source and keep the load voltage in the normal value. With the proposed control strategy, the UPQC is capable of compensating not only harmonic currents and reactive power of the load but also grid voltage distortion. And there is no harmonic interference between harmonic-producing loads and harmonic-sensitive load, which are connected on the common bus. The performance of a UPQC with the proposed control scheme under nonlinear load and grid voltage distortion is investigated using simulation as well as experiment works.