Differential battery equalization method and device for AC/DC grid-connected battery energy storage system

Abstract

The invention relates to a differential battery equalization method and device for an AC / DC grid-connected battery energy storage system. The method comprises the following steps of based on the nominal voltage, SOC, SOH, SOF and rated capacity information of each sub-module battery in the battery energy storage system, obtaining the chargeable and dischargeable energy of each sub-module in each bridge arm, each bridge arm and each phase in the battery energy storage system, pre-distributing the charging and discharging power of each phase, the charging and discharging power of each bridge arm and the charging and discharging power of each sub-module in each bridge arm, and when a battery current instruction value corresponding to the pre-distributed power of each sub-module exceeds a battery current limit value corresponding to an SOF, redistributing the charging and discharging power of the sub-modules and three phases in each bridge arm, and according to the three-phase charging and discharging power obtained through redistribution, through a zero-sequence voltage injection method and the direct-current adjustment, redistributing the three-phase alternating current side power and the three-phase direct current side power respectively, thereby realizing the three-phase inter-phase equalization. When the method is used for the differential equalization of the battery energy storage system, the equalization effect is better.

Description

technical field [0001] The present application relates to the technical field of battery energy storage, in particular to a differential battery balancing method, device, computer equipment and storage medium for an AC-DC grid-connected battery energy storage system. Background technique [0002] With the development of battery energy storage technology, the modular multi-level battery energy storage system is easy to achieve high power due to its large capacity, and can be connected to AC and DC grids at the same time, with power control and differential control from AC ports and DC ports The ability and the characteristics of wide application have been more and more widely used. [0003] Due to differences in production batches, usage environments, and operating conditions, differences between batteries are inevitable; and differences between different types of batteries are more significant. In order to eliminate the impact of differences in batteries, a battery balancing...

AI Technical Summary

Problems solved by technology

This equalization method, when the capacities of different types of batteries differ greatly, at this time, the SOC cannot reflect the relative relationship between the power and energy of different batteries, and the equalization control with the goal of keeping the SOC consistent may lead to In the case of repeated jumps in the flow direction of the equalized power, the desired effect cannot be achieved, and the equalization method generally only considers the equalization of one port (DC port or AC port), which limits the applicability of the method and cannot give full play to the modularization Advantages of battery energy storage system

Therefore, the current battery energy storage system difference battery equalization scheme has the problems of incomplete consideration and poor equalization effect

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