A SOC self-balancing control method for parallel operation of multiple energy storage modules

Abstract

The invention discloses a SOC self-balancing control method for parallel operation of multiple energy storage modules, and constructs a DC micro-grid system in which multiple distributed energy storage modules are connected in parallel; BMS obtains the average value of the output current of each lithium battery energy storage module and its individual The difference between the relative average value of the module SOC; the droop control strategy required by the parallel connection of the modules to ensure that the modules can smoothly realize the grid-connected control of multiple modules; the balance control loop of the output power between each parallel-connected module to improve the output power of the grid-connected energy storage module Unbalanced phenomenon; at the same time, add SOC balance control to ensure that the power of each energy storage module is basically the same. The algorithm proposed by the invention not only ensures the smooth grid connection of each lithium battery energy storage module, but also ensures that each module outputs power safely, reliably and in a balanced manner under both dynamic and steady state conditions.

Description

technical field [0001] The invention relates to a SOC self-balancing control method for parallel operation of multiple energy storage modules, which is an algorithm for performing balanced control discharge according to the current actual power of each energy storage module. Background technique [0002] With the vigorous development of electric energy storage technology in recent years, its forms have become more and more diverse, such as superconducting magnetic energy storage, supercapacitor energy storage, lithium batteries, etc. The development of DC converter grid-connected technology is of great significance to the development of electric energy storage. [0003] Traditional high-power charging devices generally adopt a two-level topology, which has broad application prospects in DC microgrids and is currently the mainstream circuit structure of low-voltage DC microgrids for ships. However, since each energy storage module exists independently, there is a certain err...

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Problems solved by technology

However, since each energy storage module exists independently, there is a certain error in sampling, which leads to the problem of circulating current in low-power operation and unbalanced output current in high-power operation.

[0004] In the academic field, scholars have proposed to apply the droop control theory in the AC field to the DC converter field; however, the traditional droop control can only ensure the normal grid connection, and cannot guarantee the normal current sharing control of each energy storage module; this is The discharge balance of the energy storage medium cannot be taken into account, which eventually leads to the greater difference in the remaining power of the energy storage module as the discharge time becomes longer

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