Energy balanced control method and device for energy-storage power supply system and balanced system

Abstract

The invention relates to an energy balanced control method and device for an energy-storage power supply system and a balanced system. The method comprises the following steps: during charging balanced control, acquiring actually stored electric energy of each energy storage module, and finding the minimal electric energy; calculating an error value between each of the other electric energy and the minimal electric energy, and judging the amplitude of each of the error values and a first set balanced threshold value, wherein for each of the error values exceeding the first set balanced threshold value, corresponding energy storage branches are controlled to perform charging according to corresponding PWM (Pulse-Width Modulation) control pulses; and during discharging balanced control, finding the maximal electric energy, and calculating an error value between the maximal electric energy and each of the other actual electric energy, wherein for each of the error values exceeding a second set balanced threshold value, corresponding energy storage branches are controlled to perform discharging according to the corresponding PWM control pulses. In the previous two situations, duty ratios of the PWM control pulses are in reverse proportion to the error values. Corresponding charging and discharging energy distribution is performed according to the energy state of each energy storagemodule, so that energy balanced control is realized.

Description

technical field [0001] The invention relates to an energy balance control method, a control device and a balance system of an energy storage power supply system, and belongs to the technical field of energy balance control of an energy storage power supply system. Background technique [0002] With the rapid development of the national new energy industry and smart grid construction, the application of large-scale energy storage systems is becoming more and more extensive. Limited by the structure of the PCS and the size of the DC bus voltage, the current energy storage power system generally uses multi-branch Parallel connection is used to meet the capacity and power requirements of the application scenario. According to the different topological structures of the DC side modules of the PCS, the access forms of the branches of the energy storage system are divided into two methods: centralized confluence access and sub-module access. Among them, the sub-module connection fo...

AI Technical Summary

Problems solved by technology

However, the branch output architecture of conventional energy storage systems does not have any form of energy management and control components, and only relies on automatic energy balance between parallel battery packs

With the passage of system running time, the internal resistance of each branch is different. Although the external voltage of each branch is consistent during operation, the actual stored electric energy of each branch has been different. For such differences, as long as The system can recover automatically after a long enough rest time. However, as large-scale energy storage has higher and higher requirements for the number of daily charging and discharging cycles, each branch cannot get enough automatic equalization time. With the increase of the number of cycles , the energy difference will become more and more prominent, resulting in the actual charge and discharge energy of the system shrinking greatly. In addition, when any branch of multiple parallel subsystems is out of operation and needs to be put into operation after recovery, it must be It can be put into operation only after its capacity state is adjusted to the same level, which also greatly reduces the efficiency of operation and maintenance

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