Research On Harmonic Suppression Technology Of Improved Dc Side Active Power Filter

With various electronic equipments widely used in the electricity distribution network, they bring a large number of harmonics into the power grid. Power system harmonics not only affect the quality of the grid, but also endanger the safe operation of the entire power grid. Therefore, an effective way to suppress harmonic in electric disciplinary area has become a hot research spot.The traditional passive power filter (Passive Filter, PF) suppresses only the specific number of harmonics, and is easy to generate series resonance in the process of suppressing the harmonic. APF (Active Power Filter, APF), as a dynamic suppression of harmonics and the compensation device of reactive power, is one of the most effective means to suppress harmonic pollution, it can solve all problems which the passive power filter can not work out properly. Many kinds of nonlinear loads, such as the bridge rectifier, are widely used, DC side active power filter (Direct Current Side Active Power Filter, DCSAPF) will bring significant economic benefits and value in the comprehensive management of power quality. The present study is funded by the newly independent program of Chongqing University State Key Laboratory of Power Transmission Equipment & System Security and New Technology (item number: 2007DA10512709304).This thesis mainly includes generation and management of harmonic, the control strategies and research status of APF, the basic theory of the filter, the new proposed topology of DC side APF, the simulation of the new topology, the optimal designing and selection of the main circuit parameters and the debugging of experimental equipments.Firstly, this thesis comprehensively introduces the generation and damage of the harmonic, the definition and quantification of the harmonic, the method of harmonic suppression, the basic theory of the filter, the research status and classification of APF, all the popular control strategies and programs of APF and so on.Subsequently, as to the DC side APF series-type, it has some shortages as follows using too large capacitor, the stability of the load output voltage which is over-reliance on the voltage of energy storage capacitor, the complexity of the control and drive circuits, the disadjustment of the output voltage. On the basis of researching into the low loss of inductance and low switch stress buck-boost topology family which has double inductors and double switches,the thesis puts forward the model of main circuit whose output voltage can be adjusted, and use the same frequency accompanying bandwidth correspondingly control to simplify the control and drive circuits. Because of the smaller adjustable range and the greater distortion of inductor current in the department of zero point, article proposes an improved DC side APF circuit topology. At the same time, working principle of improved DC side APF as well as the direction of power flow and the output voltage ripple is analyzed; a large-signal dynamic model is established; the corresponding control equations are derived and the PI regulator of improved DC side APF is designed. Through constant frequency hysteresis control and the average current control, the system of DC side APF is simulated. The simulation results show that the topology is rational and feasible in principle, furthermore, have laid a certain foundation for the experimental device simultaneously.Then, according to the simulation experiments and parameters selection, experimental parameters are selected optimally, and experimental program and module circuits are designed fully. The circuit is debugged, and gives some experimental waveforms. Results of experiment and simulation are analyzed in detail. Those show the correctness of improved DC side APF topology.Finally, the improved single-phase DC-side APF is applied to the three phase improved DC-side APF system. And proposed three-phase harmonic injection structure of improved DC side APF, the harmonic injection method reduces the number of active switches, as a result the cost reduced greatly. Simultaneously, owing to the traditional PI regulator which is badly in dynamic and real-time, article introduces a multi-vector error amplifier to overcome the shortcomings of traditional regulator.