A method for balancing the state of charge of a grid-connected battery energy storage system with multiple branches in parallel
A battery energy storage system and state-of-charge technology, which is used in charge balancing circuits, battery circuit devices, and AC network load balancing, etc. question
Active Publication Date: 2022-07-26
ZHEJIANG DAYOU IND CO LTD HANGZHOU SCI TECH DEV BRANCH CO +2
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Problems solved by technology
With the gradual application of decommissioned power batteries in the battery energy storage system in the future, this problem will become more and more obvious. It is manifested that as the SOH of each battery pack gradually decays, the degree of SOH dispersion increases, and the offline setting in the traditional droop control method It is difficult to adjust the parameters of the droop curve in time, resulting in the inaccurate allocation of the overall output power
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[0041] The technical solutions of the present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
[0042] The embodiment of the present invention provides a method for balancing the state of charge of a grid-connected battery energy storage system with multiple branches in parallel, such as figure 1 shown, including the following steps:
[0043] S1: Definition of the state of charge SOC of the energy storage battery pack.
[0044] The state of charge refers to the ratio of the remaining capacity of an energy storage battery after being used for a period of time or left unused for a long time to its capacity in a fully charged state, usually expressed as a percentage. The ampere-hour integration method is considered to be the most commonly used SOC estimation method due to its simplicity and effectiveness. Its definition is shown in Equation (1):
[0045]
[0046] Among them,...
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The invention relates to the field of grid-connected battery energy storage systems, in particular to a method for balancing the state of charge of a grid-connected battery energy storage system with multiple branches in parallel, including the definition of the state of charge (SOC) of an energy storage battery pack; The state of health of the battery pack is defined by SOH; the maximum available capacity Q of each battery pack is obtained max_i , calculate the initial state of health SOH of each battery pack 0i ;The definition takes into account the depth of discharge DOD and the cumulative number of cycles C acu The SOH calculation formula. Calculate the SOH of each battery pack i ;Set the SOC index n in SOC balance according to the SOC difference of each energy storage battery group; set the initial droop coefficient m SOH、SOC ; When the SOC difference of each energy storage battery group is greater than the threshold d, execute the energy storage battery group SOC balancing strategy; when the energy storage battery group SOC difference is less than the threshold d, the energy storage battery group SOC balancing strategy exits. The invention realizes the SOC balance of the state of charge of all energy storage battery packs, and at the same time takes into account the influence of SOH on the SOC balance, and solves the problem of unreasonable power distribution caused by the decrease of the maximum available capacity of the battery pack.
Description
technical field [0001] The invention relates to the field of energy storage battery grid-connected systems, in particular to a method for balancing the state of charge of a grid-connected battery energy storage system with multiple branches connected in parallel. Background technique [0002] In order to solve the uncertainty of renewable energy power generation, and also to meet the needs of grid frequency regulation and peak shaving and valley filling, the energy storage battery system in microgrid has developed rapidly in recent years. Lithium battery, as the carrier of electrical energy storage in energy storage system, has excellent discharge and charge volt-ampere battery curves, and is convenient for later maintenance. However, limited by its own physical properties, the capacity or power of a single battery cannot satisfy medium and large loads, so a multi-energy storage battery pack system is introduced to meet the load. [0003] In a multi-energy storage battery p...
Claims
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IPC IPC(8): H02J7/00H02J3/32
CPCH02J7/0048H02J7/005H02J7/0014H02J3/32Y02E40/10
Inventor 郑伟彦单立新吴靖陈佩军金明蒋燕萍赵海荣赵欢伟
Owner ZHEJIANG DAYOU IND CO LTD HANGZHOU SCI TECH DEV BRANCH CO