Flexible parallel connection device suitable for energy storage battery

Abstract

The invention relates to a flexible parallel connection device suitable for an energy storage battery. An independent capacitor is added to a battery pack string, and flexible adjustment of the voltage of the battery pack string is realized through the control of an isolated DC / DC converter to the independent capacitor, and flexible parallel connection of different battery pack strings in an energy storage system is achieved, the flexible parallel connection device can be applied to the energy storage system adopting a new battery and a echelon utilization battery, and different brands or different specifications of lithium ion batteries can be adopted in different groups of strings working in parallel; the simple and efficient serial-parallel implementation problem of the battery pack string in the energy storage system is solved; meanwhile, the use mode of the echelon utilization battery is taken into consideration.

Description

technical field [0001] The patent of the present invention relates to the field of energy storage applications, in particular to the field of energy storage applications using lithium-ion batteries as energy storage elements. technical background [0002] With the continuous development of new energy sources, especially the rapid growth of new energy sources such as intermittent and fluctuating photovoltaics and wind power, the fluctuations caused by the power grid are very large, and a power storage unit is needed to stabilize the power fluctuations of such power generation units ;The current user-side load, especially the peak-to-valley difference of industrial and commercial loads, is very large. Increasing the power storage unit can reduce the peak-to-valley difference of power load. Considering the national peak-valley electricity price, there is also a corresponding business model; With the continuous emphasis on energy storage and the continuous promotion at the polic...

AI Technical Summary

Problems solved by technology

[0003] Lithium-ion batteries are all in the form of single cells. Due to the limitation of battery cell capacity, large-capacity lithium-ion battery energy storage systems are the result of a large number of single cells connected in series and parallel. At present, the traditional form is that several single cells are connected in parallel. After that, they are connected in series to form a battery string, and multiple battery strings are connected in series and parallel to form a large-capacity energy storage system. However, the internal resistance of lithium-ion batteries is very small. It takes a lot of time and effort to connect the two battery strings from independent to parallel.

In addition, especially for batteries used in cascades, the difference between the battery cells in the same battery string is relatively large, and the difference between the battery strings is also very large, resulting in a large reduction in the capacity of the lithium battery energy storage system connected in parallel, and cannot play its due effect.

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