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Dual active bridge (DAB)-based large-power dual-modular hybrid energy storage system and grid-connected method thereof

A hybrid energy storage system and hybrid energy storage technology, applied in the direction of DC network circuit devices, electric vehicles, electrical components, etc., can solve problems such as low voltage, low work efficiency, and large current stress of converters, so as to ensure stability and realize Quantity, the effect of solving the terminal voltage reduction

Active Publication Date: 2018-11-23
SHANGHAI MARITIME UNIVERSITY
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Problems solved by technology

[0003] Therefore, the present invention provides a DAB-based high-power dual-modular hybrid energy storage system and a grid-connected method, in order to solve the problem caused by the self-discharge effect of the supercapacitor energy storage device in the existing DAB-based hybrid energy storage system before being connected to the grid. The voltage is far lower than the rated voltage of the energy storage side, which causes the technical problem of high current stress and low working efficiency of the converter in the early stage of the DC microgrid.

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  • Dual active bridge (DAB)-based large-power dual-modular hybrid energy storage system and grid-connected method thereof
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  • Dual active bridge (DAB)-based large-power dual-modular hybrid energy storage system and grid-connected method thereof

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[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0036] Dual active bridge converter (DAB) and its simplified topology such as figure 1 As shown, DAB is composed of two H-bridges and a high-frequency transformer T with a transformation ratio of n and its leakage inductance 7, where the H-bridge on the primary side is composed of a switching tube Q 1 , Q 2 , Q 3 and Q 4 The H-bridge on the secondary side is composed of a switching tube Q 5 , Q 6 , Q 7 and Q 8 composition. The primary side terminal voltage is U 1 , the secondary terminal voltage is U 2 , the rated voltage of the primary side is U 1_rated , the rated voltage of the secondary side is U 2_rated ,Have The calculation formula of the voltage at both ends of the DAB and the matching degree k of the transformer ratio is as follows: Obviously, k=1 when the primary and secondary terminal voltages are both rated volta...

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Abstract

The invention proposes a dual active bridge (DAB) converter-based large-power dual-modular hybrid energy storage system and a grid-connected method thereof. The hybrid energy storage system is mainlycharacterized in that a hybrid energy storage unit employs H bridges as basic units to modularize a DAB, and the combination of H bridges in the hybrid energy storage unit is changed by switching of an isolation switch so as to change a working mode. With regard to DC buses with different voltage classes and power demands, the hybrid energy storage unit module is expanded to two chain structures of input parallel output series (IPOS) and input parallel and output parallel (IPOP) by cascading. By the system, the converter and the energy storage device cannot be added, and internal energy transmission of the hybrid energy storage unit during off-network is achieved. By the mode, the voltage ratio matching degree of the supercapacitor DAB can be optimized in advance, the problem that a grid-connected front end is low in voltage caused by a self-discharging effect of the supercapacitor and the efficiency of the converter is reduced brought by poor voltage ratio matching degree at initial period of grid connection are solved, and the stability of the DC bus is ensured.

Description

Technical field: [0001] The invention relates to the field of DC microgrid hybrid energy storage, in particular to a high-power modular hybrid energy storage system based on a dual active bridge converter (Dual Active Bridge, DAB for short) and a grid connection method. Background technique: [0002] With the development of DC microgrid technology, the types and quantities of high-power loads are also increasing. Although the power conversion system can realize the voltage and power control of DC microgrid, its dynamic performance is poor, and it cannot meet the requirements of high-power load switching. For transient power demand, the introduction of hybrid energy storage system can effectively reduce the impact of high-power load switching on the system. Hybrid energy storage systems are usually complemented by energy storage devices with high energy density and high power density. For example, lithium batteries are used to meet the requirements of large-capacity energy, a...

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Application Information

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IPC IPC(8): H02J1/00H02J7/34
CPCH02J1/00H02J7/345
Inventor 李晗郭燚张权宝邱冠超赵怡波
Owner SHANGHAI MARITIME UNIVERSITY
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