| The modern power electronics technology is a double-edged sword. Human are always willing to enjoy convenient and effective life brought by it, but cannot avoid its adverse impact. As the development of modern power electronics technology, a huge amount of nonlinear loads are being used in industrial production and daily life which lead to serious harmonic pollution in power grid. Both power quality and system stability are decreased. Active power filter is an effective measure for harmonic pollution in power grid. Besides, APF is also a research focus at present. In practical application, APF is not popularized yet. Therefore, researches on APF have a broad prospect and huge market development potential.The three-phase three-wire shunt APF was taken as research object in this thesis, and two kinds of harmonic detection measures adopted instantaneous reactive power principium and two kinds of tracking control strategies were mainly studied. The main contents of the thesis are as follows:The working principle of APF was described, and mathematical model of voltage source converter topology was derived. Then, amplitude-frequency characteristic and system function on Butterworth filter were introduced. Subsequently, ip-iq and id-iq harmonic detection methods were discussed, which take instantaneous reactive power as theoretical basis and Butterworth filter as low pass filter. After, triangular comparing and deadbeat SVPWM control strategy were introduced.Under the platform of MATLAB/SIMULINK, two kinds of APF control system models were established, including triangular comparing and deadbeat SVPWM control strategy. Both of them were simulated on condition that three-phase steady loads and dynamic loads respectively. The results of simulation indicate:under condition of steady loads, the compensation result of deadbeat SVPWM control strategy is better than triangular comparing control strategy’s; under condition of dynamic loads, the two control strategies’ compensation results are almost the same, the latter is slightly better than the former.Parameters calculation and parts selection ways of APF main circuit were described. APF main circuit was established, which consists of three-phase AC power source, Intelligent Power Module (IPM), filter capacitor, smoothing reactor, three-phase rectifier bridge and resistance-inductance load. Meanwhile, control circuit taken DSP TMS320F2812as control core was established, including voltage and current sampling circuit, Digital Signal Processor console unit, driving circuit, protection and alarm circuit and so on. Besides, accuracy correction, protection circuit validation and related debugging work have been done.In according to design idea of modularization program, main program and each subprogram module were designed and programmed, including CAP1interruption subprogram, CAP2interruption subprogram, A/D sampling and accuracy correction subprogram, Butterworth low pass filter subprogram, harmonic calculation subprogram, incremental PI subprogram, triangular comparing tracking control subprogram, deadbeat method generating instruction voltage subprogram, SVPWM tracking control subprogram.Under the condition of low voltage, the APF control system was debugged as a whole. The final compensation results of triangular comparing control strategy and partial experiment results of deadbeat SVPWM control strategy were achieved. The results show that the algorithm of triangular comparing method is correct and reliable, the program running speed of it is fast, and the fundamental and harmonic can be calculated rapidly and accurately. Certain filtering effects have been obtained. In deadbeat SVPWM control strategy, repetitive predictor can forecast instruction current correctly. Besides, the correctness of SVPWM program was validated separately. |
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