Research On The Key Technology Of Three-Phase Shunt Active Power Filter

In modern society, power is the most convenient and widely of clean energy for users of all the power and energy, if no power, modern civilization will not run properly. To build a solid smart grid to ensure high standards of power quality is benefit to the improvement of people’s living standard. However, power is widely used by people, but also brings serious pollution to the grid system, it affects the power quality of the system. Among them, one of the major factors that affects power quality is harmonic pollution.This paper stuty two key technologies of the three-phase shunt active power filter which are harmonic current detection technology and system control technology,then d esigning the main circuit is the foundation.For the main circuit parameters and mathematical model, this paper gives the system structure, describes the working principle of the three-phase shunt APF, it simplifies the circuit, on the basis of this, it establishes of a mathematical model of three-phase stationary frame and d-q coordinates, then it explains the principles and implementation method of SVPWM modulation in detail. Finally, around the control objectives and engineering implementation of the APF, it analyzes and designs respectively the system operating frequency, bus voltage, bus capacitance, network inductance, network filter and other main circuit parameters for a more detailed.For harmonic current detection method, this paper describes the current harmonic detection technology, and then it analyzes emphatically harmonic current detection algorithm of research-based Discrete Fourier Transform(DFT), and then it is applied to extracting harmonic instruction for the three-phase shunt active power filter and it builds a simulation model and a simulation test in the simulink of MATLAB.Simulation results show that DFT harmonic detection algorithm can accurately detect each harmonic of the periodicity load and it is appropriate for three-phase systems.The controller is the core of APF system, is also one of the key technologies studied emphatically in this article. It mainly uses the feedforwarde control, PI control, repetitive control and other technology. This paper uses a dual closed-loop control strategy of the inner current loop and outer voltage loop, the outer voltage loop PI controller is adopted on the dc side voltage stability control, for inner current loop, the paper studies comparatively the PI control and "PI + repetition" hybrid control, and it describes how to design the parameters of the PI controller, repetitive control in detail, and finally it has the simulation analysis for controller designed in the simulink of MATLAB.Finally, it builds a system model of three-phase three-wire shunt APF by MATLAB platform, respectively, double loop PI control and complex current control of "Repeat Control + PI control" of current inner are compared, the correctness of APF mathematical modeling,the main circuit parameters, harmonic instruction extraction algorithm and dual-loop controller design is verified by MATLAB simulation.