DC micro power grid system equipped with energy storage units and control method

Abstract

The invention relates to a DC micro power grid system equipped with energy storage units and a control method. A new energy unit is connected with a DC bus through a first converter and is connected with an AC main power grid through a second converter. A first energy storage unit and a second energy storage unit are connected with the DC bus through a third converter and a further converter respectively and are connected with a DC load through the DC bus. Compared with a product in the prior art, the DC micro power grid system has advantages of stabilizing DC micro power grid bus voltage, achieving energy optimization and coordination control, and prolonging a storage battery service life. Further, a DC bus voltage change factor decides the operating states of the converters under different control layers, solves problems of DC bus voltage stabilization and energy optimization and coordination control, and achieves a purpose of improving system electric energy quality and power supply reliability.

Description

technical field [0001] The invention relates to a direct current microgrid system and a control method, in particular to a direct current microgrid system including an energy storage unit and a control method. Background technique [0002] In order to make full use of the advantages of distributed generation of renewable energy and reduce the negative impact of distributed generation on large power grids, American scholars R.H.Lasseter and others first proposed the concept of microgrids in 2001. A microgrid connects several distributed power sources (DERs), energy storage systems (ESSs) and loads in an area, and connects them to the large power grid through a power electronic interface. The microgrid can be regarded as a "grid within a grid", which can be operated in an isolated island or connected to the grid. Distributed power generation is the only way to solve the future energy crisis, and the microgrid as a form of "grid within a grid" is an effective way to reliably c...

AI Technical Summary

Problems solved by technology

[0003] Most of the existing research discusses the operation and control of the DC microgrid under the grid-connected operation, ignoring the coordinated control between micro-sources and energy storage. When the energy in the grid is excessive or seriously insufficient, it will have a serious impact on the stable operation of the DC microgrid.

At the same time, existing technologies often cannot have both energy density and power density. For example, supercapacitors have high power density, but their energy density is low, while lead-acid batteries have high energy density, but their power density is relatively low. Low, the use of a single energy storage has limited effect on suppressing new energy power fluctuations

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