The Research And Revised Design On Buffer Circuit Of Distribution Static Synchronous Compensator

In our distribution network system, because of inductive components, capacitance components and non-linear element use increases gradually, makes the power grid, there are a lot of reactive power and every harmonic, not only increased power loss, reduce the power distribution network of electric energy quality, and a threat to the safe operation of the power grid and restricted the development of national economy. In recent years, along with the rapid development of the power electronic technology, all kinds of compensation technology also got a very good development, in many compensation devices, the most prominent is stationary distribution network synchronization compensator (D-STATCOM).As a new Var compensator, D-STATCOM attracts extensive attention for its perfect performance such as accurate, immediate and syntheses compensation. In order to apply to power distribution network, this paper design a three-phase four-leg D-STATCOM device, the device can be good for existing in the distribution network of the harmonic current, the unbalance current, zero sequence and negative sequence current of compensation, improve power quality in the grid.But the three-phase four-leg D-STATCOM device also has some questions, such as power switching device switch loss is big and impulse current impulse voltage, can damage power tube and threat the whole compensation devices running safety. In order to ensure power tube work safety, the main circuit of D-STATCOM device must be installed buffer circuit.Buffer circuit has been further researched in this paper:First various buffer circuit and its basic circuit structure have been introduced; Then, two kinds of buffer circuit, RCD buffer circuit and Undeland circuit, theories and technology are mature, were further discussed, through the study of the two kinds of buffer circuit opened and shut off in the process of the energy transfer, which according to two buffer circuit for the different situations different changes, make its function become more perfect; At the end of the article, the MATLAB/Simulink mathematical simulation model of three-phase four-leg D-STATCOM device and buffer circuit has been introduced, the D-STATCOM with traditional buffer circuit and improved buffer circuit in simulated, by comparing the simulation results then draw the final conclusion.