The Research Of Key Issues And Application For Low Voltage Distribution Grid Active Power Filter

As the rapid development of modern industrial technology and civil construction industry, the nonlinear load in low voltage power distribution grid increase rapidly. Various nonlinear and time.varying electronic current transformer, such as inverter, rectifier, and a variety of switching power supply in industrial production and daily life are more and more widely used, its pollution to the power grid is increasingly serious, the devices consume a large amount of reactive power from the power grid, and generate a large number of harmonics into the power grid, lead to serious deformation of the grid voltage and current waveform. Harmonic pollution affects the safe, reliable and economic operation of the power grid and electric equipment, influence the power quality of people to producting and living, and even cause disaster. Therefore, the harmonic governance has become the problem is an urgent need to solve in the field of electrical engineering. Active Power Filter(APF for short) is a kind of new Power electronic devices which can dynamic compensate the harmonic and reactive Power, even their size and frequency are constant changing. So it is a kind of ideal device to compensating harmonic and reactive Power. In recent years, Tri-level three-leg APF was paid more and more attention to with low du/dt, small current ripple, and low switching frequency, in three-phase four-wire system of low voltage distribution grid.This thesis mainly discusses the circuit design and the two key technologies in depth study of Tri-level three-leg APF in the three-phase four-wire system, completed the following research:(1) Propose design schemes of each hardware circuit part of the APF, determine the harmonic current detection method and modulation strategy of power conversion circuit.(2) The detailed design of the APF in all parts of hardware circuit, and makes a preliminary debugging.(3) Thorough discuss the improved FBD harmonic current detection method.(4) Make a detailed analysis of3D-SVPWM (three-dimensional space vector pulse width modulation) technology based on a-b-c coordinate. (5) Establish a three-level APF experiment platform based on DSP TMS320C28335, satisfy the complex control requirements of three-phase four-wire Tri-level three-leg APF, verify the design and the research of this article with experiment.