earticle

영어

With the continuous expansion of the scale of distributed power generation，multi grid connected converters often prone to oscillation problems when parallel operation.In this paper,we study the equivalent circuit of parallel connection of multi grid connected converters , system response characteristics of voltage source and in-depth analysis of the causes of the parallel oscillation of the converters.This paper analyzes converter’s parallel complex vector model by complex vector and comes to a conclusion that power grid voltage feed-forward will produce strong coupling between converter so that cause oscillation parallel converters. In view of the above problems and the flow of the converter starting or the voltage fluctuation of the grid, we design a low feed forward method, that is to make the fundamental and the main sub components of the grid voltage forward without delay and for the relative high frequency components, the filter technology is used to attenuate, so as to achieve the maximum elimination of the feed-forward coupling between the converter, to prevent the occurrence of system oscillation. In order to verify the use of this paper, the theory of the parallel converter is applied in the field of MW level wind field. The experimental results prove the correctness of the theory.