DC microgrid group system and novel layered control method thereof

Abstract

The invention discloses a DC microgrid group system and a novel layered control method thereof. The DC microgrid group system includes three DC sub-microgrids, each of the DC sub-microgrids includes three BUCK converters, each BUCK converter is connected to a DC bus through a connection line, and the resistance of a connection line of each BUCK converter in the sub-microgrid is not equal to each other. The invention provides the novel layered control method which can be divided into three layers of control in total. The top layer is DC microgrid group coordinated control, and the main goal ofthe layer is to coordinate the sub-microgrids to achieve the current distribution of any ratio between the sub-microgrids. The second layer is voltage compensation control and droop coefficient correction control, and the main goal of the layer is to improve the control accuracy of the DC bus voltage and improve the current distribution accuracy between DC converters in the sub-microgrids. The bottom layer is droop control and voltage single-closed-loop control, and the main goal of the layer is to perform quick and reliable tracking control on a control result obtained by an upper layer. According to a layered control algorithm proposed by the invention, the arbitrary ratio distribution of the current between the sub-microgrids is realized, the current distribution precision of the converters in the sub-microgrids is improved, and the control error of the DC bus voltage is reduced.

Description

technical field [0001] The invention belongs to the field of direct current micro-grid control of electric power system, relates to a novel layered control method, in particular to a control method based on output voltage compensation control, variable droop coefficient control, and sub-micro-grid power coordination control and the control method using the method A DC microgrid system. Background technique [0002] With the access of a large number of renewable new energy sources, the concept of micro grid has been proposed. Microgrids can be divided into AC microgrids and DC microgrids. Compared with the AC micro-grid, the DC micro-grid can improve the utilization rate of the converter and reduce the loss, which is conducive to the complementary advantages and coordinated control of the various micro-sources, and the DC system does not have phase synchronization, harmonics, and reactive power losses. Therefore, DC microgrid has become a new research direction of microgrid...

AI Technical Summary

Problems solved by technology

When the line resistances are not equal, the sum of the virtual resistance of each converter and the line resistance is also not equal, resulting in a decrease in shunt accuracy

[0005] At present, domestic research on DC microgrids is still in its infancy, and the control of DC microgrids is more complicated than that of a single DC microgrid.

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