Study Of A Novel Coordinate Control Strategy Of Unified Power Quality Conditioner

A unified power quality conditioner (UPQC) consists of two PWM converters with one common DC bus. It has the features of integrating voltage and current compensation links, multiple functions and high performance-price ratio. Owing to the strong coupling characteristics between the two PWM converters, it brings difficulties on the control of UPQC. Large capacitors are usually adopted to stabilize the voltage of DC bus, it also causes the problems of the size increasing and the performance decreasing for UPQC. To solve those mentioned problems above, based on vector control technique, a novel coordinate control strategy is presented for both PWM converters together with the DC bus in this paper. Using this method, the two converters are first decoupled, then composed double close-loop control structures respectively, and implemented PI control alone.The typical circuit topology, operation principles and power flow are first analyzed, and the mathematic models based on dq rotating coordinate axis are established for UPQC. And the mechanism of the novel coordinate control strategy is studied for series and shunt converters, the design for suggested controller and the parameters of key components for main circuit topology are provided. The UPQC simulation model based on MATLAB/Simulink is established, and simulation research is conducted. Based on dSPACE experiment platform, the MATLAB/dSPACE on-line simulation model of UPQC is established, and the primary experiment result of the UPQC system is got. It is shown from both the simulation and the primary experiment results that the UPQC system with suggested control strategy has the features of fast response performance, and effectively suppressing harmonics.