| Power quality related to the merits of the overall effectiveness of the national economy. With the increasing complexity of grid structure and the power load components, a number of types of power quality problems which are at the same power distribution system or in the same load at the same time have increased. Therefore, unified power quality conditioner (UPQC) which has comprehensive ability of compensation becomes the hot research topic of power compensation. The status quo of respective voltage compensation and respective current compensation can be changed by UPQC. It can meet the synchronous compensation requirements of load voltage sag and power supply harmonic current and has far development prospects. To improve the actual quality of power supply problems, to improve the actual supply of power quality problems, in-depth study UPQC including of principle, topology, the compensation component of real-time detection algorithm, control strategy and the actual circuit design problems.The main research contents and innovation:1. The three-phase three-wire UPQC topological structure is considered as the research object on the basis of researching various topology structures. Series compensator is connected in series with the supply voltage through a transformer and parallel compensator is connected in parallel with the load. The detecting algorithm of harmonic current compensation signal based on PSO-FUZZY control is proposed. The factors of fuzzy controller with integrator are optimized by particle swarm optimization to adjust the output of fuzzy controller. Aiming at the problem of easily falling into local minimum during particle swarm optimization process, an improved algorithm of PSO is proposed, in which several particles are added to expand the searching scope in the iterative process. The feasibility of the detection algorithm is verified by MATLAB/Simulink simulation results and experimental results.2. Based on current and voltage vector characteristics of the different voltage compensation strategy, energy flow characteristics of series and parallel compensation unit is analyzed, the active power and reactive power calculation formula is derived. Aiming at the problem of voltage sag with phase jump, considering phase jump based on instantaneous reactive theory minimum energy compensating voltage detection algorithm is proposed. Compensation optimal angle is get according to the principle of minimum active power provided by series converter in three circumstances of supply voltage fluctuations. Target function of voltage is acquired and compensation output of series side is get. The feasibility of the symmetrical component minimum energy compensation algorithm is verified by MATLAB/Simulink simulation results and experimental results.3. Based on the mathematical model of UPQC parallel compensation unit, combined with harmonic current compensation principle, the current hysteresis optimal vector control method is proposed to make up for the low accuracy of traditional three-phase hysteresis control method. The optimal output vector of next moment is determined by the area of current optimal vector and current error. The simple way to determine the area of supply voltage vector and current error vector is acquired according to coordinate geometry. Repeated computation is avoided and compensation accuracy is improved. Simulation model is built to verify the superiority. And experimental verification is carried out in the UPQC experimental device based on DSP platform. The feasibility of the method is verified by MATLAB/Simulink simulation results and experimental results.4. Design the experiment platform UPQC though detailed theoretical derivation and rigorous mathematical calculation based on the minimum energy method. Including the power devices selection, parallel side of the sense of connection inductance value, core, turns and wire diameter design, capacity and ratio of transformations design in series, output filter circuit design in series and parallel, as well as the capacity values and the design pressure of DC capacitor design.
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