An event-triggered SOC balancing control method for a multi-battery energy storage system

Abstract

The present application relates to the technical field of power energy storage, and particularly relates to a multi-battery energy storage system SOC equalization control method based on event triggering, aiming at the phenomenon of large calculation and periodic communication overhead in the prior art, and solving the problem of limited SOC equalization control accuracy in a large-scale system. The core of the method is to combine a distributed dynamic equalization control protocol and an event triggering mechanism to realize on-demand communication and power distribution among multiple batteries in the system, and to reduce the communication frequency and calculation complexity of the system. The method is suitable for multi-battery energy storage systems with high efficiency and reliability requirements.

Description

Technical Field

[0001] This invention relates to the field of power energy storage technology, and in particular to a SOC equalization control method for multi-battery energy storage systems based on event triggering, applicable to multi-battery energy storage systems. Background Technology

[0002] With the rapid development of renewable energy and electric vehicles, battery energy storage systems (BESS) composed of multiple batteries connected in series or parallel are becoming increasingly widely used. To ensure the safety, efficiency, and lifespan of the system, it is crucial to ensure a balanced state of charge (SOC) among the batteries within the group. An imbalanced SOC can lead to overcharging or over-discharging of some batteries, accelerating their aging and even causing safety hazards.

[0003] Existing multi-cell SOC equalization methods are mainly divided into centralized and distributed approaches. Centralized methods rely on a central controller to collect information from each cell and make unified decisions, which carries the risk of single-point failure and poor system scalability. Distributed methods achieve coordinated control through local communication between cell units, offering higher reliability and flexibility, and are currently a research focus. However, existing distributed equalization methods often employ periodic communication and control strategies, i.e., information exchange and state updates occur at fixed time intervals. This approach has significant drawbacks: firstly, communication regardless of significant changes in cell state generates a large amount of unnecessary communication traffic, wasting bandwidth and computing resources; secondly, a fixed cycle makes it difficult to balance system response speed and control accuracy, resulting in poor adaptability under dynamic operating conditions.

[0004] Therefore, developing a multi-battery SOC equalization method that can effectively reduce communication and computing overhead while ensuring high-precision collaborative control is of great practical significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention designs an event-triggered distributed controller based on dynamic average consistency, which triggers communication by using deviations in charging and discharging capability parameters, thereby reducing communication load.

[0006] This invention employs the following scheme to implement a state-of-the-art (SOC) equalization control method for a multi-battery energy storage system based on event triggering, comprising the following steps:

[0007] Step S1: Construct a SOC equalization control model for a multi-battery energy storage system;

[0008] Step S2: Design a distributed dynamic balancing control protocol to allocate the output power of each battery in a multi-battery energy storage system;

[0009] Step S3: Design the event triggering mechanism;

[0010] Step S4: Determine the initial values ​​of the SOC and related auxiliary parameters of each battery in the multi-battery energy storage system, and calculate the initial values ​​of the charge and discharge capacity parameters and the initial value of the output power of each battery.

[0011] Step S5: Use the distributed dynamic equilibrium control protocol and event triggering mechanism to allocate the output power of each battery in the multi-battery energy storage system and update the SOC of each battery; determine whether the SOC of each battery has reached consistency. If they have reached consistency, output the SOC balancing result of each battery; otherwise, continue to execute step S5.

[0012] Further, step S1 specifically includes:

[0013] A state-of-charge (SOC) equalization control model for a multi-battery energy storage system is constructed. The model includes: the objective function for SOC equalization control of the multi-battery energy storage system; the total power supply and demand balance constraints of the multi-battery energy storage system; the SOC constraints of each battery in the multi-battery energy storage system; and the output power constraints, which are as follows:

[0014]

[0015]

[0016]

[0017]

[0018] in, ; The number of batteries in a multi-battery energy storage system; Let the SOC of the i-th battery at time t be... Let SOC be the average value of each battery in a multi-battery energy storage system at time t, satisfying... ; The minimum SOC of the i-th battery. The maximum SOC of the i-th battery; Let be the output power of the i-th battery at time t. For the total power requirements of a multi-battery energy storage system, Let be the minimum output power of the i-th battery. Let be the maximum output power of the i-th battery.

[0019] Further, step S2 specifically includes:

[0020] Step S21: Design a distributed dynamic load balancer control protocol, specifically as follows:

[0021]

[0022] in, Let m be the trigger time of the i-th battery. For the i-th battery Next trigger moment The time of the m-th triggering of the j-th battery; ; Let i be the set of batteries that can communicate with the i-th battery. Adjacency matrix of battery communication topology The element in the i-th row and j-th column:

[0023]

[0024] Let be the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t; for The first derivative with respect to time t; Let be the gradient tracking term for the i-th battery at time t; and To control the gain; Here are the charge / discharge capability parameters for the i-th battery at time t:

[0025]

[0026] The discharge capacity parameter of the i-th battery at time t The charging capability parameter of the i-th battery at time t The calculation methods are as follows:

[0027]

[0028]

[0029] in, Let be the output voltage of the i-th battery at time t. Let be the aging parameters of the i-th battery at time t;

[0030] Step S22: Allocate the output power of each battery in the multi-battery energy storage system, specifically as follows:

[0031] .

[0032] Further, step S3 specifically includes:

[0033] Design an event triggering mechanism:

[0034]

[0035] in, Let i be the event trigger function for the i-th battery, and , It is a norm; The event trigger threshold, The lower bound.

[0036] Further, step S4 specifically includes:

[0037] Determine the initial value of the SOC of the i-th battery. The initial value of the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t is... The initial value of the gradient tracking term for the i-th battery is... ; Calculate the initial value of the discharge capacity parameter of the i-th battery. Calculate the initial value of the charging capability parameter of the i-th battery. Calculate the initial output power value for the i-th battery discharge mode. The initial output power value in the i-th battery charging mode is .

[0038] Furthermore, the specific condition for determining whether the SOC of each battery reaches the same level in step S5 is as follows:

[0039]

[0040] in, Let the state of charge (SOC) of the j-th battery be at time t. This is the preset consistency tolerance threshold.

[0041] This invention provides a state-of-the-art (SOC) equalization control method for multi-battery energy storage systems based on event triggering. Compared with existing technologies, the advantages of this invention are:

[0042] 1. This invention can achieve coordinated control and balancing. It utilizes a distributed dynamic balancing control protocol to realize the power demand allocation and SOC balancing control among multiple batteries, thereby avoiding battery overcharging or over-discharging.

[0043] 2. The distributed architecture facilitates the addition or removal of battery nodes, resulting in strong system scalability.

[0044] 3. By using an event-triggered mechanism, the frequency of computation and communication is significantly reduced, improving the system's real-time performance and cost-effectiveness, and reducing a large amount of communication costs. Attached Figure Description

[0045] Figure 1 This is a flowchart of an event-triggered SOC equalization control method for a multi-battery energy storage system according to the present invention.

[0046] Figure 2 This is a communication topology diagram of the multi-battery energy storage system of the present invention;

[0047] Figure 3This is a schematic diagram illustrating the SOC balancing control of each battery in this invention;

[0048] Figure 4 This is a diagram showing the power distribution of each battery in this invention;

[0049] Figure 5 This is a comparison chart of event triggering in this invention and traditional periodic triggering. Detailed Implementation

[0050] The embodiments of the present invention are described in detail below, and the examples and results of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0051] Example 1:

[0052] The flowchart of the event-triggered SOC equalization control method for a multi-battery energy storage system provided in this embodiment is as follows: Figure 1 As shown, it includes the following steps:

[0053] Step S1: Construct a SOC equalization control model for a multi-battery energy storage system;

[0054] Step S2: Design a distributed dynamic balancing control protocol to allocate the output power of each battery in a multi-battery energy storage system;

[0055] Step S3: Design the event triggering mechanism;

[0056] Step S4: Determine the initial values ​​of the SOC and related auxiliary parameters of each battery in the multi-battery energy storage system, and calculate the initial values ​​of the charge and discharge capacity parameters and the initial value of the output power of each battery.

[0057] Step S5: Use the distributed dynamic equilibrium control protocol and event triggering mechanism to allocate the output power of each battery in the multi-battery energy storage system and update the SOC of each battery; determine whether the SOC of each battery has reached consistency. If they have reached consistency, output the SOC balancing result of each battery; otherwise, continue to execute step S5.

[0058] In this embodiment, step S1 specifically includes:

[0059] A state-of-charge (SOC) equalization control model for a multi-battery energy storage system is constructed. The model includes: the objective function for SOC equalization control of the multi-battery energy storage system; the total power supply and demand balance constraints of the multi-battery energy storage system; the SOC constraints of each battery in the multi-battery energy storage system; and the output power constraints, which are as follows:

[0060]

[0061]

[0062]

[0063]

[0064] in, ; The number of batteries in a multi-battery energy storage system; Let the SOC of the i-th battery at time t be... Let SOC be the average value of each battery in a multi-battery energy storage system at time t, satisfying... ; The minimum SOC of the i-th battery. The maximum SOC of the i-th battery; Let be the output power of the i-th battery at time t. For the total power requirements of a multi-battery energy storage system, Let be the minimum output power of the i-th battery. Let be the maximum output power of the i-th battery.

[0065] In this embodiment, step S2 specifically includes:

[0066] Step S21: Design a distributed dynamic load balancer control protocol, specifically as follows:

[0067]

[0068] in, Let m be the trigger time of the i-th battery. For the i-th battery Next trigger moment The time of the m-th triggering of the j-th battery; ; Let i be the set of batteries that can communicate with the i-th battery. Adjacency matrix of battery communication topology The element in the i-th row and j-th column:

[0069]

[0070] Let be the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t; for The first derivative with respect to time t; Let be the gradient tracking term for the i-th battery at time t; and To control the gain; Here are the charge / discharge capability parameters for the i-th battery at time t:

[0071]

[0072] The discharge capacity parameter of the i-th battery at time t The charging capability parameter of the i-th battery at time t The calculation methods are as follows:

[0073]

[0074]

[0075] in, Let be the output voltage of the i-th battery at time t. Let be the aging parameters of the i-th battery at time t;

[0076] Step S22: Allocate the output power of each battery in the multi-battery energy storage system, specifically as follows:

[0077] .

[0078] In this embodiment, step S3 specifically includes:

[0079] Design an event triggering mechanism:

[0080]

[0081] in, Let i be the event trigger function for the i-th battery, and , It is a norm; The event trigger threshold, The lower bound.

[0082] In this embodiment, step S4 specifically includes:

[0083] Determine the initial value of the SOC of the i-th battery. The initial value of the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t is... The initial value of the gradient tracking term for the i-th battery is... ; Calculate the initial value of the discharge capacity parameter of the i-th battery. Calculate the initial value of the charging capability parameter of the i-th battery. Calculate the initial output power value for the i-th battery discharge mode. The initial output power value in the i-th battery charging mode is .

[0084] In this embodiment, the specific condition for determining whether the SOC of each battery reaches the same level in step S5 is as follows:

[0085]

[0086] in, Let the state of charge (SOC) of the j-th battery be at time t. This is the preset consistency tolerance threshold.

[0087] Example 2:

[0088] Example 2 uses the MATLAB / Simulink simulation platform to verify the proposed event-triggered SOC equalization control method for a multi-battery energy storage system. The system has four batteries, and the communication topology of each battery is an undirected ring structure, as shown below. Figure 2 The communication topology diagram of the multi-battery energy storage system of the present invention is shown.

[0089] The initial parameters of each battery in the multi-battery energy storage system are shown in Table 1:

[0090] Table 1

[0091] Battery i Battery SOC Aging parameters Output voltage (V) Current (A) 1 0.5629 0.9907 3.72 0 2 0.5812 0.9953 3.74 0 3 0.4254 0.9564 3.55 0 4 0.5827 0.9957 3.74 0

[0092] Determine the initial values ​​of relevant auxiliary parameters in the multi-battery energy storage system and calculate the initial values ​​of the charge / discharge capacity parameters and output power of each battery:

[0093] The initial value of the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t is ; Calculate the initial value of the discharge capacity parameter of the i-th battery. Calculate the initial value of the charging capability parameter of the i-th battery. Calculate the initial output power value for the i-th battery discharge mode. The initial output power value in the i-th battery charging mode is The initial value of the gradient tracking term for the i-th battery is... The rated voltage of each battery is: The load current in battery discharge mode is In battery charging mode, the load current is Consistency control gain is The tracking control gain is The event trigger threshold is The adjacency matrix is The degree matrix is The Laplace matrix is .

[0094] The above parameters are incorporated into the distributed dynamic balancing control protocol and event triggering mechanism, and the battery's charge / discharge capacity parameters are used to allocate the output power of each battery in the multi-battery energy storage system, thereby balancing the SOC of each battery. It is then determined whether the SOC of each battery has reached a consensus. If they have, the SOC balancing result of each battery is output; otherwise, step S5 is continued. The determination condition is... The consistency tolerance threshold is .

[0095] Finally, the effectiveness of the invention is verified through numerical simulation using the given data. Figure 3 This is a schematic diagram illustrating the SOC balancing control of each battery in this invention. Figure 3 It can be seen that the maximum deviation of SOC of each battery decreased from the initial 0.15 to below 0.02, and the convergence time was about 6750 seconds. Figure 4 This is a diagram showing the power distribution of each battery in this invention. Figure 4 It can be seen that the power curve during the discharge stage changes synchronously with the sinusoidal fluctuation of the load current. During the charging stage, the output power of each battery is stable at around -32.4W, and the total power value is stable at around -129.5W. The actual total power is equal to the sum of the output power of each battery and is consistent with the required total power. Figure 5 This is a comparison chart of the event triggering of the present invention and the traditional periodic triggering, by... Figure 5 It can be seen that compared with the traditional 2-second cycle triggering, the communication frequency of the event triggering mechanism of the present invention is reduced by 32.1%.

[0096] It should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for SOC equalization control of a multi-battery energy storage system based on event triggering, characterized in that, Includes the following steps: Step S1: Construct a SOC equalization control model for a multi-battery energy storage system; Step S2: Design a distributed dynamic balancing control protocol to allocate the output power of each battery in a multi-battery energy storage system; Step S3: Design the event triggering mechanism; Step S4: Determine the initial values ​​of the SOC and related auxiliary parameters of each battery in the multi-battery energy storage system, and calculate the initial values ​​of the charge and discharge capacity parameters and the initial value of the output power of each battery. Step S5: Use the distributed dynamic equilibrium control protocol and event triggering mechanism to allocate the output power of each battery in the multi-battery energy storage system and update the SOC of each battery; determine whether the SOC of each battery has reached consistency. If they have reached consistency, output the SOC balancing result of each battery; otherwise, continue to execute step S5.

2. The event-triggered SOC equalization control method for a multi-battery energy storage system according to claim 1, characterized in that, Step S1 specifically involves: A state-of-charge (SOC) equalization control model for a multi-battery energy storage system is constructed. The model includes: the objective function for SOC equalization control of the multi-battery energy storage system; the total power supply and demand balance constraints of the multi-battery energy storage system; the SOC constraints of each battery in the multi-battery energy storage system; and the output power constraints, which are as follows: in, ; The number of batteries in a multi-battery energy storage system; Let the SOC of the i-th battery at time t be... Let SOC be the average value of each battery in a multi-battery energy storage system at time t, satisfying... ; The minimum SOC of the i-th battery. The maximum SOC of the i-th battery; Let be the output power of the i-th battery at time t. For the total power requirements of a multi-battery energy storage system, Let be the minimum output power of the i-th battery. Let be the maximum output power of the i-th battery.

3. The event-triggered SOC equalization control method for a multi-battery energy storage system according to claim 2, characterized in that, Step S2 specifically includes the following steps: Step S21: Design a distributed dynamic load balancer control protocol, specifically as follows: in, Let m be the trigger time of the i-th battery. For the i-th battery Next trigger moment The time of the m-th triggering of the j-th battery; ; Let i be the set of batteries that can communicate with the i-th battery. Adjacency matrix of battery communication topology The element in the i-th row and j-th column: Let be the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t; for The first derivative with respect to time t; Let be the gradient tracking term for the i-th battery at time t; and To control the gain; Here are the charge / discharge capability parameters for the i-th battery at time t: The discharge capacity parameter of the i-th battery at time t The charging capability parameter of the i-th battery at time t The calculation methods are as follows: in, Let be the output voltage of the i-th battery at time t. Let be the aging parameters of the i-th battery at time t; Step S22: Allocate the output power of each battery in the multi-battery energy storage system, specifically as follows: 。 4. The event-triggered SOC equalization control method for a multi-battery energy storage system according to claim 3, characterized in that, Step S3 specifically involves: Design an event triggering mechanism: in, Let i be the event trigger function for the i-th battery, and , It is a norm; The event trigger threshold, The lower bound.

5. The event-triggered SOC equalization control method for a multi-battery energy storage system according to claim 4, characterized in that, Step S4 specifically involves: Determine the initial value of the SOC of the i-th battery. The initial value of the dynamic parameters of the i-th battery in a multi-battery energy storage system at time t is... The initial value of the gradient tracking term for the i-th battery is... ; The initial value of the discharge capacity parameter of the i-th battery is calculated. Calculate the initial value of the charging capability parameter of the i-th battery. Calculate the initial output power value for the i-th battery discharge mode. The initial output power value in the i-th battery charging mode is .

6. The event-triggered SOC equalization control method for a multi-battery energy storage system according to claim 5, characterized in that, The specific condition for determining whether the SOC of each battery is consistent in step S5 is as follows: in, Let the SOC of the j-th battery at time t be... This is the preset consistency tolerance threshold.

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