Research And Design On The Control System Of The Shunt Active Power Filter

The demand for power electronic devices is increasing in modern social. But the power electronic devices can cause the serious harmonic pollution of power system because of the nonlinear, impact and volatility of the power electronic devices. Today, active power filter (APF) is recognized as one of the most effective method to solve the harmonic pollution and improve the power quality. And it is also an important development direction of harmonic control in the future. APF is a complex power filtering device of integrated power electronic technology, digital signal processing, harmonic detection and compensation control technology of multiple technology. It can track the changes of the harmonic amplitude and frequency. And APF is a hot research topic in the field of smart grid.Firstly, this paper introduces the harmonic generation, damage and control in power system. And two common methods of harmonic control, which are passive filter and APF technology, are comparative analysis. The advantages and disadvantages of these two kinds of harmonic control technology are analyzed in detail. Based on the understanding of advantages for APF, such as filtering effect, dynamic response and controllability, the research statuses of the domestic and overseas for APF are introduced. The main circuit structure, the harmonic current detection and compensation current control technology of active filter key are discussed and the future development trend is analyzed.Secondly, this paper introduces the working principle of APF and several key technologies of APF are researched. In the detection technology of harmonic current, the p-q detection method and ip-iq detection method based on the theory of instantaneous reactive power are studied. The characteristics and application of the two detection methods are analyzed, and the harmonic current detection technology of APF which is suitable for the design of this paper is selected. The direct current control technology, which includes two methods of hysteresis comparison and triangular carrier, is researched. The advantages and disadvantages of the two control techniques are studied. In capacitor voltage control of DC side, this paper designs a voltage control method based on active power compensation. This kind of control method is simple and convenient, and it also saves hardware investment.Thirdly, the experimental prototype of parallel type three-phase APF is designed according to the performance index. The design of experimental prototype include the designs of main circuit and control system. The main circuit of APF, including the converter part, DC side part and the input/output part, is designed. The device parameters of the main circuit are designed in detail, and the detailed design ideas and algorithms are given. The control system, including signal detection, main control circuit and protection circuit, is designed. Each sub module of hardware and software of the control system is designed in detail and specific design circuit diagram of each module is given. At the same time, the software part of the system of control design, each module is given software flow chart.Finally, in order to verify the design parameters and algorithm of active power filter, this paper builds a model of APF based on the MATLAB simulation software. The simulation results show that the detection algorithm of harmonic current, control algorithm of compensation current and the voltage control algorithm of DC side capacitor are effective. The simulation results show that the design parameters and algorithms can achieve the expected design requirements.