Resonant Control of a LCL-based Unified Power Quality Conditioner with Active Damping Scheme

In this paper, a synchronous reference frame control scheme is presented to control a Dual unified power quality conditioner (UPQC) using Proportional-Resonant Controllers.in Dual control strategy, the series active filter is controlled as a sinusoidal Current source and shunt active filter is controlled as a sinusoidal voltage source. The main focus of this paper is to present the optimal design procedure of output passive filters of the converters. This results in decrease of cost and bulkiness of the overall system. On the other hand, by using a LCL filer at the Series active filter output, better attenuation of high order harmonics as well as increased dynamic is achieved. In order to accede system required stability and reduce the system losses, the oscillations in both active filters are actively damped. In this case, the series damping resistors are eliminated and the capacitor current is used as feedback to the control system. The UPQC with the proposed scheme not only is capable of reducing unbalances, harmonics and voltage sag in grid voltage, but also compensates the harmonic currents of nonlinear load. Simulations in MATLAB software environment demonstrates the effective performance of the system under different conditions.