Study On Unified Power Quality Conditioner Based On Model Predictive Control And Kalman Filtering

Power quality problems become gradually complicated and serious in power systems. The unified power quality conditioner (UPQC), an integration of series and shunt power active filters, has the overall capabilities of regulating power quality. In order to solve power quality problems such as harmonic distortions and instantaneous voltage disturbances existing at both supply and consume sides in power distribution systems, the UPQC based on model predictive control (MPC) and Kalman filtering is studied in this thesis. The main contents of the thesis are as follows:Power quality problems and progress of the techniques for solving power quality problems are outlined. The conception of UPQC is introduced, and the research status of topological structures, measuring methods and control methods of UPQC is investigated in detail.The basic topology, principle and function of UPQC are analysed. Some kinds of UPQCs with improved or expanded topological structures and their characteristics and advantages are introduced. The equivalent circuit of the UPQC with topological structure is presented and analysed, and subsequently the state-space model of the UPQC is established for the design of measurement and control.Researches are detailedly carried out into UPQC based on state-space model, measuring method using Kalman filtering and control method using MPC. The principle, characteristics and design method of Kalman filtering are illuminated, and a new Kalman filtering measuring method for UPQC is proposed. The principle, characteristics and design method of MPC control are illuminated, and a new MPC control method for UPQC is also proposed.Further researches are focused on control methods for UPQC. Taking into account the characteristics of UPQC, a series of MPC related strategies such as MPC with a feedforward linear regulator, jointed feedforward MPC and feedback MPC and asynchronized MPC, are proposed based on the basic MPC strategy to improve the performance of UPQC for overall power qulity regulation.Simulation studies are implemented by the designs of the algorithms of Kalman filtering and a series of MPC related and the simulation circuits of UPQC using Matlab/Simulink, and experimental studies are also implemented using dSPACE experimental installation. Both simulation and experimental results illustrate that the measuring method using Kalman filtering can detect power quality problems correctly and rapidly, the control method using MPC related strategies can control power quality effectively in real time, the UPQC based on MPC control and Kalman filtering can solve power quality problems such as voltage and current harmonic distortions and instantaneous voltage disturbances existing at both supply and consume sides in power distribution systems, and has the overall capabilities of regulating power quality.