Research On Control Strategy And Device Development Of Dynamic Voltage Restorer

With the increasing of nonlinear load and impulsive load in power system,the power quality problem is becoming more and more prominent.Among all power quality problems,voltage sag has the most serious impact on precision equipment.Dynamic voltage restorer(DVR)is used to solve the problem of voltage sag.In this paper,the fuzzy self-tuning PID control strategy of DVR is studied and the hardware experiment platform is built.Firstly,the main causes of voltage sag and the methods to improve power quality are summarized.The topology of dynamic voltage restorer is applied to medium and low voltage side and its working principle,compensation strategy and software phase locking method are analyzed.Second,the mathematical model of single-phase DVR is established.In this paper,Fuzzy PID self-tuning control system of dynamic voltage restorer is designed with fuzzy control theory and PID theory controller based on feedforward control and voltage instantaneous value feedback control.Then,PID parameters are adjusted by Z-N critical proportional band method.The main circuit and control circuit based on fuzzy PID and traditional PID are built on MATLAB/Simulink platform,then the second order butterworth filter suitable this system has been designed with impulse response invariant method.Through the simulation analysis of the system side voltage disturbance,the conclusion can be drawn: Fuzzy self-tuning PID control is superior to traditional PID control in response speed and stability.at the same time,the quality of compensation voltage is improved by adding digital filter.In the end,TMS320F2812 is selected as main control chip for high-speed data processing and algorithm implementation,and STM32F103C8T6 is selected as peripheral and control chip.On the hardware side,main circuit,driving circuit,power supply circuit and protection circuit of the dynamic voltage restorer are designed.In software,main program and part of the functional modules of the program flow are worked out.The feasibility and effectiveness of the hardware circuit parameter selection is verified by the principle experiment of the dynamic voltage restorer device on the experimental platform.