Research On APF Based On Improved UPF And SVPWM Control Technology

This study is an important part of the Doctoral Program of Higher Education of the Ministry of Education (NO.20101402120004). A large number of harmonic currents are injected into the grid due to the development of power electronic technology and the widely application of power electronic devices. The voltage waveform of the power system is distorted due to the harmonic current, and the distorted waveform results in the degradation of power quality. Thus the harmonic suppression has become an important part of the power quality control. The passive power is used in traditional harmonic suppression method.In recent years more and more people began to study the active power filter for the passive power filter can only filter out a specific one or two harmonics and is related to the system impedance.The system configuration and working principle of a three-phase shunt active power filter are analyzed in this article.Then a three-phase shunt APF experimental device is designed, and finally the experimental results are obtained. The following issues are the main contents of this article.The history and current situation as well as its classification of APF is described in this paper. The system configuration and working principle of a shunt APF is analyzed emphatically, finnaly, Research on APF based on improved UPF and SVPWM control technology is established.Highly accurate and real-time harmonic detection method is the premise of the effective elimination of harmonics for APF,The algorithm of The UPF (Unity Power Factor) harmonic detection adopted by this paper is simple because it does not need the coordinate transformation,Then a phase-locked loop is used to inhibit the distorted voltage waveform.The mathematical model of the power circuit for APF is established, the current tracking control method based on SVPWM is used successfully in the APF.And finally an expected experimental result is obtained. For DC voltage control, the reason for the fluctuation of DC voltage is analyzed in details from the perspective of energy exchange between DC capacitor and the grid.The design of the main parameters in the main circuit of the active power filter is introduced, including the DC capacitor and voltage value, the inductance value of the AC side. Then a simulation model is built in the Matlab/Simulink environment. The simulation results are presented and analyzed, which demonstrate the accuracy of the control method and selected parameters.A three-phase shunt APF Experimental circuit is designed. The APF Experimental circuit consists of control circuit and main circuit. The control circuit based on DSP consists of sampling and conditioning circuit, PLL frequency multiplier circuit and keyboard-display circuit. The main circuit based on IPM consists of driving circuit, PDPINTA protection circuit, overvoltage and undervoltage protection circuit and startup current limiting circuit of the DC side. Then, A hardware harmonic detection system circuit including unit sine and cosine waves generating circuit synchronous with grid voltage, Addition and subtraction circuit, Multiplier circuit and LPF-circuit based on ip-iq is designed.The assembly language program of APF is written on CCS3.1.Software system is mainly composed of the initialization program, the main program, The harmonic detection and control program. The initialization program is used to set the corresponding registers. The main program includes the keyboard and display. The control program is used to detect the harmonic current, current tracking control and interrupt saver.In the end, experimental results are obtained by hardware and software debugging. The experiment results show that the main harmonic components in the power side are suppressed effectively when the APF is running. And eventually achieve the purpose of harmonic suppression. At the same time,In the hardware harmonic detection system, The unit sine and cosine waves synchronous with grid voltage are obtained, The addition and subtraction circuits has been verified by experimental data, The multiplier module debugging also made a great progress.