Deadbeat Current Control Based On Space Vector For Active Power Filter

This study is a part of the Doctoral Program of Higher Education of the Ministry of Education (20101402120004). It is proposed on the growing problem of harmonic pollution in the power grid. Compared with the passive filter, active power filter (APF) has the advantage of the dynamic compensation of harmonics and reactive power, so it has become an effective measure to solve the harmonic problem and improve power quality. It will be widely used in electric power and industry.The structure and basic principle of the three-phase three-wire shunt APF is analyzed in this article. The harmonic detection methods are studied and the deadbeat current control mothod based on space vector is determined. On this basis, some hardware circuits and software system of APF is designed.The APF can realize the harmonic compensation. The main contents of this article are as follows:The domestic and international research trends, classification and basic principle of APF is described. The ip-iq method based on instantaneous reactive power and the harmonic current detection method based on the unity power factor (UPF) are studied. Through analyzing the advantages and disadvantages of these methods, the UPF method is used to detect harmonic. The phase-locked loop is added and the moving window integration algorithm is used to achieve low-pass filter in this method so as to suppress the influence of voltage distortion and enhance the real-time of detection.The mathematical model of the APF is established and the voltage space vector control is studied. In order to improve the real-time performance of the compensation current tracking control, the voltage space vector control and the deadbeat control are combined as the control method of APF system. The linear prediction, the parabolic prediction and the repeated prediction observer is studied. For DC voltage control, the PI regulator is used to maintain the stability of the DC voltage, and the design methods of the PI parameters are described.The design methods of the main circuit parameters for APF are introduced. The ip-iq method, the UPF method and its improved method are studied using MATLAB. The results show that the UPF improved method can suppress the influence of voltage distortion and get the good real-time of detection.The simulation model of APF which using the above three prediction methods is built on MATLAB.The simulation results prove the feasibility and effectiveness of the selected control scheme, it also show that the predicted effect of repeated prediction observer is best, so it is used to get forecasting current.Some hardware circuits of APF are designed, including the TMS320F2812DSP as the core of the control circuit, drive circuit and protection circuit, and through debugging to make them work properly.The software system is designed using the C language on the basis of the hardware circuit. It includes the main program and interrupt service routines. The main program includes the initialization procedure, keyboard scanning and processing subroutine and display routines.Interrupt service routines include interrupt of three capture units, interrupt of CPU timer and interrupt of power drive protection.These programs can achieve the harmonic current detection algorithm, the deadbeat current control algorithm based on space vector, the PI control algorithm, display, and protection functions by debugging.The hardware and software experimental platform for APF is established, and experimental studies are carried out.The experiment results prove that the feasibility and effectiveness of the harmonic detection method and control scheme.The APF can operate reliably and achieve the main harmonic compensation, especially for low harmonics.