Modulation method suitable for state of charge equalization of multi-module battery module set

Abstract

The invention discloses a modulation method suitable for the state of charge equalization of a multi-module battery module set. The method comprises the following steps that: (1) the SOC (state of charge), voltage and current information of sub-module battery module sets is collected initially in one calculation cycle; (2) the number of switched-on modules is determined according to the voltage information and control output reference voltage signals; and (3) the SOC of the battery module sets of an energy storage system are sorted according to a descending order, and the serial numbers and switching-on statuses of the switched-on modules are determined according to the operation status of the system and an SOC equalization relationship. Compared with an existing modulation method, the modulation method provided by the present invention can reduce the switching loss of the energy storage system, ensure that the THD of the output voltage and current of the energy storage system meet requirements, and can be applied to single-phase and three-phase systems; and the modulation method of the present invention can realize the automatic equalization of the SOC of the module battery modulesets during a modulation process. According to the modulation method adopted, the complexity of the control of the system is reduced, and SOC equalization control and power control are free of coupling.

Description

Technical field [0001] The invention belongs to the technical field of level modulation, and in particular relates to a modulation method suitable for balancing the state of charge of a multi-module battery module. Background technique [0002] The scale expansion of new energy power plants and microgrids, as well as the increased demand for peak and frequency modulation of urban power grids, the distributed energy storage capacity is small and the voltage level is also low, and the battery energy storage system is developing in the direction of large capacity and high access voltage. The energy storage system based on the cascaded multilevel topology has modular characteristics. Through the increase of the number of cascaded stages, the single unit capacity of the energy storage system can be increased while the system can be directly connected to the grid. In large-scale energy storage systems Gradually be recognized and applied. [0003] In an energy storage system with a casca...

AI Technical Summary

Problems solved by technology

The existing cascaded energy storage systems mostly use CPS-PWM as the modulation method of the main circuit of the system, which requires a large number of modulation waves and takes up more software and hardware resources, especially when the voltage level of the energy storage system is high. , that is, when the number of cascaded modules required is large, the CPS-PWM modulation method has the problems of small phase shift angle and difficult realization of precision requirements

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