A DC microgrid system and its control method

Abstract

The present invention provides a DC microgrid system, which includes: a DC bus, a grid-connected converter, a first DC / DC converter, and a storage battery; the first DC / DC converter converts the DC power from the DC bus into a voltage of The DC power required by the battery is sent to the battery, and the DC power from the battery is converted into a DC power whose voltage meets the requirements of the DC bus bar and sent to the DC bus bar; and the first DC / DC converter also transmits to the grid-connected converter through the data communication line Battery SOC value and battery charge and discharge power information; the grid-connected converter selects one of the grid-connected free mode, forced inverter mode, and forced rectification mode to work according to the battery SOC value, and also according to the battery charge and discharge power information and setting The adjustment parameters, calculate the power and work according to the calculated power, so that the power of the DC bus can be maintained in balance. The invention can prolong the service life of the accumulator in the direct current microgrid and improve the quality of electric energy supplied by the direct current microgrid.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a DC microgrid system and a control method thereof. Background technique [0002] With the sharp increase in the application of renewable energy in modern power grids, DC microgrids have more prominent competitive advantages in low-voltage power distribution and residential applications. Such as figure 1 The coordinated control methods of the shown DC microgrid are mainly divided into centralized control methods, distributed control methods and decentralized control methods. figure 1 In, LC means local controller, DG means distributed micro-source, CC means centralized controller, dotted line means communication line connection, #n means number. [0003] The power quality of the centralized control method is the best, but the centralized control method requires a central controller, and there must be a communication line between the central There is no need for any com...

AI Technical Summary

Problems solved by technology

[0003] The power quality of the centralized control method is the best, but the centralized control method requires a central controller, and there must be a communication line between the central There is no need for any communication lines between the controls, and the investment cost is the lowest, but the DC bus voltage fluctuates in a large range and the power quality is poor; the performance of the distributed control method is between the previous two control methods, and the investment cost is far greater than that of the distributed control method. control mode, better power quality

In summary, the current control methods of DC microgrids mainly focus on one aspect of low investment cost or high power quality, and control methods that take into account both rarely appear

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