Research On Shunt Active Power Filter

The harmonic pollution problem of the power system is severe day by day, and the people's demand of power reliability and power quality is higher than before. The traditional passive filter could not meet the users'demand of power quality. Active Power Filter (APF) may overcome the disadvantages of the traditional approaches for eliminating harmonics (such as the passive filter). With the superexcellent performance, APF has obtained more attention.First, the background, development and future prospect of active power filter is described in detail. Then, the thesis introduces the classifications and topology structure of the active power filters. Especially further analyses are made on the operational principle of the shunt active power filter and its mathematical model.Secondly, the thesis introduces several typical kinds of current detection methods. Detail studies are made on the two kinds of real time harmonic and reactive current detection methods, which are based on instantaneous reactive power theory, and the comparison is got between them.Thirdly, shunt active power filter's control strategy including compensatory current control and DC voltage control is analyzed in detail. Compensatory current control adopts triangle wave compare control and hysteresis control as well, and DC voltage control adopts PI closed loop control.Besides, a chip of TMS320LF2407A DSP, which is the core of the controller in the shunt active power filter circuit, is introduced in the thesis. A detail introduction of the controller, such as the power supply circuits, the communication circuits and so on, is given in the following passages. The software adopts C and Assemble languages to realize modularized programming. It introduces several programs of the controller.Lastly, regulating circuit of the three-phase shunt active power filter is analyzed and simulated by MATLAB. The proposed harmonic and reactive current detection method and the control strategy of shunt active power filter are tested. And satisfactory result is drawn. The simulation results and experiment results verify validity and effectiveness of the current detection method and the control strategy.