Series battery pack energy storage system charge and discharge control method, device and energy storage system

Abstract

The present invention discloses a charge and discharge control method, device and energy storage system for a series battery group energy storage system, which belongs to the field of energy storage systems; first, the maximum pressure difference and the initial pressure difference protection threshold between the batteries of the energy storage system are obtained, and when the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, that is, the pressure difference protection threshold is increased; then the charge and discharge of the energy storage system is controlled according to the size relationship between the maximum pressure difference and the target pressure difference protection threshold. The pressure difference protection threshold of the present application scheme is not a fixed value, and when the maximum pressure difference is greater than the initial pressure difference protection threshold, the charge and discharge of the energy storage system will not be disconnected immediately, but the charge and discharge of the energy storage system will be further controlled according to the size relationship between the maximum pressure difference and the target pressure difference protection threshold, so as to improve the utilization efficiency of each battery in the energy storage system while ensuring that each battery in the energy storage system will not be overcharged or over-discharged.

Description

Technical Field

[0001] The present invention relates to the field of energy storage systems, and in particular, to a charging and discharging control method and device for a series battery pack energy storage system, and an energy storage system. Background Art

[0002] Energy storage systems play an important role in photovoltaic and DC systems, especially in off-grid conditions, where energy storage systems are indispensable equipment units. In existing energy storage systems, batteries are generally connected in series, but due to battery production process control and other reasons, there is inevitably a phenomenon of inconsistent battery internal resistance. In energy storage systems, the direct reaction is the voltage inconsistency between series-connected batteries, forming a battery voltage difference. When the battery voltage difference is too large, it will cause overcharging or over-discharging of the battery during charging and discharging, affecting the battery life.

[0003] Therefore, the energy storage system is set with a pressure difference protection threshold when in use. When the pressure difference reaches the pressure difference protection threshold, the energy storage system will disconnect the output contactor, cut off the external power output, and start the balancing control to reduce the battery pressure difference.

[0004] In the existing energy storage system, the pressure difference protection threshold is set to a fixed value. The pressure difference protection threshold remains unchanged during the use of the energy storage system. Therefore, in order to ensure that the energy storage system can work normally under any circumstances, the pressure difference protection threshold is set to a small value. In some cases, even if the pressure difference is greater than the pressure difference protection threshold, the energy storage system can still work normally. However, according to the control method of the existing energy storage system, the output of external power will be directly disconnected, and the utilization efficiency of the energy storage system is not high. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a charging and discharging control method, device and energy storage system for a series battery pack energy storage system to solve the problem that the control mode of the existing energy storage system sets the voltage difference protection threshold to a fixed value and the energy storage system has low utilization efficiency.

[0006] The technical solution adopted by the present invention to solve the technical problem is:

[0007] First,

[0008] A charging and discharging control method for a series battery pack energy storage system comprises the following steps:

[0009] Obtaining a maximum voltage difference between batteries of the energy storage system and an initial voltage difference protection threshold;

[0010] When the maximum pressure difference is greater than the initial pressure difference protection threshold, adjusting the pressure difference protection threshold from the initial pressure difference protection threshold to a target pressure difference protection threshold, wherein the target pressure difference protection threshold is greater than the initial pressure difference protection threshold;

[0011] The charging and discharging of the energy storage system is controlled according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold.

[0012] Furthermore, obtaining the maximum voltage difference between the batteries of the energy storage system includes:

[0013] Obtaining the highest voltage value and the lowest voltage value of the battery in the energy storage system;

[0014] The maximum voltage difference is obtained by subtracting the highest voltage value from the lowest voltage value.

[0015] Further, when the energy storage system is charged, adjusting the voltage difference protection threshold from the initial voltage difference protection threshold to the target voltage difference protection threshold includes:

[0016] Obtaining a charging cut-off voltage value of the energy storage system;

[0017] Subtracting the maximum voltage value from the charging cut-off voltage value to obtain a charging difference value;

[0018] A target voltage difference protection threshold is obtained according to the charging difference and the initial voltage difference protection threshold.

[0019] Further, obtaining a target voltage difference protection threshold according to the charging difference and the initial voltage difference protection threshold includes:

[0020] A target voltage difference protection threshold is obtained by summing one half of the charging difference value and the initial voltage difference protection threshold.

[0021] Further, when the energy storage system is discharged, adjusting the pressure difference protection threshold from the initial pressure difference protection threshold to the target pressure difference protection threshold includes:

[0022] Obtaining a discharge cut-off voltage value of the energy storage system;

[0023] Subtracting the discharge cut-off voltage value from the minimum voltage value to obtain a discharge difference value;

[0024] A target voltage difference protection threshold is obtained according to the discharge difference and the initial voltage difference protection threshold.

[0025] Further, obtaining a target voltage difference protection threshold according to the discharge difference and the initial voltage difference protection threshold includes:

[0026] A target voltage difference protection threshold is obtained by summing one half of the discharge difference value and the initial voltage difference protection threshold.

[0027] Further, when the energy storage system is charged, controlling the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold value includes:

[0028] When the maximum voltage difference is not greater than the target voltage difference protection threshold, reducing the charging power of the energy storage system for charging, and performing balancing through the BMS of the energy storage system;

[0029] When the maximum voltage difference is greater than the target voltage difference protection threshold, the energy storage system is controlled to stop charging, and the energy storage system is balanced through the BMS.

[0030] Further, reducing the charging power of the energy storage system for charging includes: reducing the charging power to half for charging.

[0031] Further, when the energy storage system is discharging, controlling the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold value includes:

[0032] When the maximum pressure difference is not greater than the target pressure difference protection threshold, reducing the discharge power of the energy storage system for discharge, and performing balancing through the BMS of the energy storage system;

[0033] When the maximum pressure difference is greater than the target pressure difference protection threshold, the energy storage system is controlled to stop discharging, and the energy storage system is balanced through the BMS.

[0034] Further, reducing the discharge power of the energy storage system for discharging includes: reducing the discharge power to half for discharging.

[0035] Furthermore, it also includes: after the equalization through the BMS of the energy storage system is completed, adjusting the pressure difference protection threshold from the target pressure difference protection threshold to the initial pressure difference protection threshold.

[0036] Second,

[0037] A charging and discharging control device for a series battery pack energy storage system, comprising:

[0038] A parameter acquisition module, used to obtain the maximum voltage difference between the batteries of the energy storage system and the initial voltage difference protection threshold;

[0039] a threshold adjustment module, configured to adjust the pressure difference protection threshold from the initial pressure difference protection threshold to a target pressure difference protection threshold when the maximum pressure difference is greater than the initial pressure difference protection threshold, wherein the target pressure difference protection threshold is greater than the initial pressure difference protection threshold;

[0040] The system control module is used to control the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold.

[0041] Thirdly,

[0042] An energy storage system, comprising:

[0043] processor;

[0044] a memory for storing instructions executable by the processor;

[0045] The processor is configured to be used for the method described in the technical solution of the first aspect.

[0046] Beneficial effects:

[0047] The technical solution of the present application provides a charge and discharge control method, device and energy storage system for a series battery pack energy storage system. First, the maximum pressure difference and the initial pressure difference protection threshold between the batteries of the energy storage system are obtained. When the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, that is, the pressure difference protection threshold is increased; then the energy storage system is controlled to charge and discharge according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. The pressure difference protection threshold of the present application is not a fixed value. When the maximum pressure difference is not greater than the initial pressure difference protection threshold, the pressure difference protection threshold is the initial pressure difference protection threshold; and when the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold increases to become the target pressure difference protection threshold, and then the energy storage system is controlled to charge and discharge according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. In this way, when the maximum pressure difference is greater than the initial pressure difference protection threshold, the charging and discharging of the energy storage system will not be disconnected immediately. Instead, the pressure difference protection threshold will be increased first, and then the charging and discharging of the energy storage system will be further controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. Under the premise of ensuring that the batteries in the energy storage system will not be overcharged or over-discharged, the utilization efficiency of each battery in the energy storage system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 This is a flow chart of a charging and discharging control method for a series battery group energy storage system provided by an embodiment of the present invention;

[0050] Figure 2 This is a flow chart of a specific charging and discharging control method of a series battery group energy storage system provided by an embodiment of the present invention;

[0051] Figure 3 is a schematic diagram of the structure of an energy storage system provided by an embodiment of the present invention;

[0052] Figure 4It is a schematic structural diagram of a charging and discharging control device for a series battery pack energy storage system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present invention is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation methods obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0054] First, the terms used in the following embodiments are explained.

[0055] BMS, (BATTERY MANAGEMENT SYSTEM), monitors the battery usage status at all times, alleviates the inconsistency of the battery pack through necessary measures, and provides protection for the safe use of the battery pack.

[0056] Balance, balance control is divided into active balance and passive balance; active balance is to transfer the electric energy with high voltage to the battery with low voltage; passive balance is generally to consume the excess energy of the battery with high electric energy to achieve the purpose of consistent battery voltage.

[0057] Reference Figure 1 The embodiment of the present invention provides a charging and discharging control method for a series battery storage system, comprising the following steps:

[0058] Obtain the maximum voltage difference between the batteries of the energy storage system and the initial voltage difference protection threshold;

[0059] When the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, and the target pressure difference protection threshold is greater than the initial pressure difference protection threshold;

[0060] The charging and discharging of the energy storage system is controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold.

[0061] An embodiment of the present invention provides a method for controlling charging and discharging of a series battery pack energy storage system. First, the maximum pressure difference and the initial pressure difference protection threshold between the batteries of the energy storage system are obtained. When the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, that is, the pressure difference protection threshold is increased; then, the charging and discharging of the energy storage system is controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. The pressure difference protection threshold of the present application is not a fixed value. When the maximum pressure difference is not greater than the initial pressure difference protection threshold, the pressure difference protection threshold is the initial pressure difference protection threshold; and when the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold increases to become the target pressure difference protection threshold, and then the charging and discharging of the energy storage system is controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. In this way, when the maximum pressure difference is greater than the initial pressure difference protection threshold, the charging and discharging of the energy storage system will not be disconnected immediately. Instead, the pressure difference protection threshold will be increased first, and then the charging and discharging of the energy storage system will be further controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. Under the premise of ensuring that the batteries in the energy storage system will not be overcharged or over-discharged, the utilization efficiency of each battery in the energy storage system is improved.

[0062] As a supplementary explanation to the above embodiment, Figure 2 As shown, an embodiment of the present invention provides a specific charging and discharging control method for a series battery group energy storage system, comprising the following steps:

[0063] Obtaining the maximum voltage difference between the batteries of the energy storage system and the initial voltage difference protection threshold; wherein obtaining the maximum voltage difference between the batteries of the energy storage system includes: obtaining the highest voltage value and the lowest voltage value of the battery in the energy storage system; subtracting the highest voltage value from the lowest voltage value to obtain the maximum voltage difference;

[0064] When the maximum voltage difference is not greater than the initial voltage difference protection threshold, the existing charge and discharge state is maintained unchanged.

[0065] When the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, and the target pressure difference protection threshold is greater than the initial pressure difference protection threshold; the charging and discharging of the energy storage system is controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold.

[0066] Specifically, when the energy storage system is charged, adjusting the voltage difference protection threshold from the initial voltage difference protection threshold to the target voltage difference protection threshold includes: obtaining the charging cut-off voltage value of the energy storage system; subtracting the maximum voltage value from the charging cut-off voltage value to obtain the charging difference value; and obtaining the target voltage difference protection threshold value according to the charging difference value and the initial voltage difference protection threshold value. Preferably, the target voltage difference protection threshold value is obtained by summing half of the charging difference value with the initial voltage difference protection threshold value.

[0067] When the maximum voltage difference is not greater than the target voltage difference protection threshold, the charging power of the energy storage system is reduced for charging, and the BMS of the energy storage system is used for balancing; when the maximum voltage difference is greater than the target voltage difference protection threshold, the energy storage system is controlled to stop charging, and the BMS of the energy storage system is used for balancing. Preferably, the charging power is reduced to half for charging.

[0068] In addition, after the balancing is completed through the BMS of the energy storage system, the pressure difference protection threshold is adjusted from the target pressure difference protection threshold to the initial pressure difference protection threshold.

[0069] When the energy storage system is discharged, adjusting the pressure difference protection threshold from the initial pressure difference protection threshold to the target pressure difference protection threshold includes: obtaining the discharge cut-off voltage value of the energy storage system; subtracting the discharge cut-off voltage value from the minimum voltage value to obtain the discharge difference value; and obtaining the target pressure difference protection threshold value according to the discharge difference value and the initial pressure difference protection threshold value. Preferably, half of the discharge difference value is added to the initial pressure difference protection threshold value to obtain the target pressure difference protection threshold value. Preferably, the pressure difference protection threshold is adjusted from the target pressure difference protection threshold value to the initial pressure difference protection threshold value.

[0070] When the maximum pressure difference is not greater than the target pressure difference protection threshold, the discharge power of the energy storage system is reduced for discharge, and the energy storage system's BMS is used for balancing; when the maximum pressure difference is greater than the target pressure difference protection threshold, the energy storage system is controlled to stop discharging, and the energy storage system's BMS is used for balancing.

[0071] In addition, after the balancing is completed through the BMS of the energy storage system, the pressure difference protection threshold is adjusted from the target pressure difference protection threshold to the initial pressure difference protection threshold.

[0072] In order to further illustrate the solution of this application, Figure 3 Taking the energy storage system shown in the figure as an example, the energy storage system includes a series battery pack V1, a switch QF1, a battery management system BMS, a 24V power module V2, a DC-DC module U, a load Load, and DC contactors K1, K2, K3, and K4; the BMS controls the opening and closing of the DC contactors K1, K2, K3, and K4, and the DC-DC module realizes the charging and discharging control of the energy storage system.

[0073] According to the type of battery in the energy storage system, set the initial voltage difference protection threshold U0, the single battery charging cut-off voltage Ucs, and the single battery discharging cut-off voltage Uds;

[0074] When the energy storage system is powered on and in operation, the BMS detects the single cell voltage of the battery system in real time and calculates the voltage according to the highest single cell voltage U H and the minimum cell voltage U L Calculate the current battery voltage difference Ut, Ut = U H -U L,

[0075] When the energy storage system is charging:

[0076] If Ut≤U0, the energy storage system is charged according to the original charging parameters;

[0077] If Ut>U0, the difference ΔU1 between the highest single cell voltage UH and the charging cut-off voltage Ucs is calculated, and the target voltage difference protection threshold is set to U1=U0+ΔU1 / 2;

[0078] If U0<Ut≤U1, the energy storage system will be charged at half of the original charging power (if the original charging current is 10A, it will be charged at 5A), and the BMS balancing management will be turned on to balance the batteries. After balancing, the voltage difference protection threshold will be restored to U0;

[0079] If Ut>U1, the energy storage system stops charging and starts BMS balancing management to balance the batteries. After balancing is completed, the voltage difference protection threshold is restored to U0.

[0080] When the energy storage system is discharged:

[0081] If Ut≤U0, the energy storage system discharges according to the original discharge parameters;

[0082] If Ut>U0, the difference ΔU2 between the lowest cell voltage UL and the discharge cut-off voltage Uds is calculated, and the voltage difference protection threshold is set to U1=U0+ΔU2 / 2;

[0083] If U0<Ut≤U1, the energy storage system discharges at half of the original discharge power, and turns on the BMS balancing management to balance the batteries. After balancing is completed, the voltage difference protection threshold is restored to U0;

[0084] If Ut>U1, the energy storage system stops discharging, the BMS controls to disconnect K2 and K3, and turns on the BMS balancing management to balance the batteries. After balancing is completed, the voltage difference protection threshold is restored to U0, and K2 and K3 are closed again.

[0085] A specific charge and discharge control method for a series battery pack energy storage system provided by an embodiment of the present invention first obtains the maximum pressure difference. If the maximum pressure difference is not greater than the initial pressure difference protection threshold, normal charge and discharge are performed; if the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold; then the charge and discharge of the energy storage system is controlled according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold; if the maximum pressure difference is greater than the target pressure difference protection threshold, it indicates that the pressure difference is too large, and the energy storage system is directly controlled to stop charging and discharging; if the maximum pressure difference is not greater than the target pressure difference protection threshold, the charging power or the discharging power is reduced to half, and then balanced through the BMS; at this time, although the maximum pressure difference is greater than the initial pressure difference protection threshold, it is not greater than the target pressure difference protection threshold. Within this range, charging and discharging are performed at half of the charging power and the discharging power, which can prevent over-discharge or over-charging of the battery in the energy storage system and maximize the use efficiency of the battery.

[0086] In one embodiment, the present invention also provides a charging and discharging control device for a series battery storage system, such as Figure 4 As shown, including:

[0087] The parameter acquisition module 41 is used to obtain the maximum voltage difference between the batteries in the energy storage system and the initial voltage difference protection threshold; specifically, the parameter acquisition module 41 obtains the highest voltage value and the lowest voltage value of the battery in the energy storage system; the maximum voltage difference is obtained by subtracting the highest voltage value from the lowest voltage value.

[0088] A threshold adjustment module 42, configured to adjust the pressure difference protection threshold from the initial pressure difference protection threshold to a target pressure difference protection threshold when the maximum pressure difference is greater than the initial pressure difference protection threshold, wherein the target pressure difference protection threshold is greater than the initial pressure difference protection threshold;

[0089] When the energy storage system is charged, the threshold adjustment module 42 obtains the charging cut-off voltage value of the energy storage system; subtracts the maximum voltage value from the charging cut-off voltage value to obtain the charging difference value; and obtains the target voltage difference protection threshold value according to the charging difference value and the initial voltage difference protection threshold value. Wherein, obtaining the target voltage difference protection threshold value according to the charging difference value and the initial voltage difference protection threshold value includes: obtaining the target voltage difference protection threshold value by summing half of the charging difference value with the initial voltage difference protection threshold value.

[0090] When the energy storage system is discharged, the threshold adjustment module 42 obtains the discharge cut-off voltage value of the energy storage system; subtracts the discharge cut-off voltage value from the minimum voltage value to obtain the discharge difference value; and obtains the target pressure difference protection threshold value according to the discharge difference value and the initial pressure difference protection threshold value. Wherein, obtaining the target pressure difference protection threshold value according to the discharge difference value and the initial pressure difference protection threshold value includes: obtaining the target pressure difference protection threshold value by summing half of the discharge difference value with the initial pressure difference protection threshold value.

[0091] The system control module 43 is used to control the charging and discharging of the energy storage system according to the relationship between the maximum pressure difference and the target pressure difference protection threshold.

[0092] When the energy storage system is charging:

[0093] When the maximum voltage difference is not greater than the target voltage difference protection threshold, the system control module 43 reduces the charging power of the energy storage system for charging, and performs balancing through the BMS of the energy storage system; preferably, reducing the charging power of the energy storage system for charging includes: reducing the charging power to half for charging.

[0094] When the maximum pressure difference is greater than the target pressure difference protection threshold, the system control module 43 controls the energy storage system to stop charging and performs balancing through the BMS of the energy storage system.

[0095] When the energy storage system is discharged:

[0096] When the maximum pressure difference is not greater than the target pressure difference protection threshold, the system control module 43 reduces the discharge power of the energy storage system for discharge, and performs balancing through the BMS of the energy storage system; preferably, reducing the discharge power of the energy storage system for discharge includes: reducing the discharge power to half for discharge.

[0097] When the maximum pressure difference is greater than the target pressure difference protection threshold, the system control module 43 controls the energy storage system to stop discharging and performs balancing through the BMS of the energy storage system.

[0098] As an optional implementation of the embodiment of the present invention, after the balancing is completed by the BMS of the energy storage system, the system control module 43 adjusts the pressure difference protection threshold from the target pressure difference protection threshold to the initial pressure difference protection threshold.

[0099] An embodiment of the present invention provides a charge and discharge control device for a series battery group energy storage system, wherein a parameter acquisition module acquires a maximum pressure difference between batteries of the energy storage system and an initial pressure difference protection threshold; when the maximum pressure difference is greater than the initial pressure difference protection threshold, the threshold adjustment module adjusts the pressure difference protection threshold from the initial pressure difference protection threshold to a target pressure difference protection threshold; and a system control module controls the charge and discharge of the energy storage system according to a relationship between the maximum pressure difference and the target pressure difference protection threshold. First, the maximum pressure difference is obtained. If the maximum pressure difference is not greater than the initial pressure difference protection threshold, normal charging and discharging are performed; if the maximum pressure difference is greater than the initial pressure difference protection threshold, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold; then the charging and discharging of the energy storage system is controlled according to the relationship between the maximum pressure difference and the target pressure difference protection threshold; if the maximum pressure difference is greater than the target pressure difference protection threshold, it means that the pressure difference is too large, and the energy storage system is directly controlled to stop charging and discharging; if the maximum pressure difference is not greater than the target pressure difference protection threshold, the charging power or discharging power is reduced to half, and then balanced through the BMS; at this time, although the maximum pressure difference is greater than the initial pressure difference protection threshold, it is not greater than the target pressure difference protection threshold. Within this range, charging and discharging are performed at half of the charging power and the discharging power, which can not only prevent over-discharge or overcharging of the battery in the energy storage system, but also maximize the battery utilization efficiency.

[0100] In one embodiment, the present invention further provides an energy storage system, comprising:

[0101] processor;

[0102] a memory for storing processor-executable instructions;

[0103] The processor is configured to execute the specific charge and discharge control method for the series battery group energy storage system provided in the above embodiment.

[0104] The energy storage system provided by the embodiment of the present invention stores executable instructions of the processor in the memory. When the maximum pressure difference is greater than the initial pressure difference protection threshold, the processor adjusts the initial pressure difference protection threshold to the target pressure difference protection threshold, and then controls the charging and discharging of the energy storage system according to the relationship between the maximum pressure difference and the target pressure difference protection threshold. The pressure difference protection threshold of the energy storage system in the embodiment of the present invention is not a fixed value. When the maximum pressure difference is greater than the pressure difference protection threshold, the pressure difference protection threshold is adjusted to improve the use efficiency of the battery while ensuring the safety of the energy storage system.

[0105] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0106] It should be noted that, in the description of this application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0107] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0108] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0109] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0110] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0111] The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0112] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0113] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A charging and discharging control method for a series battery storage system, characterized in that: The following steps are involved: Obtaining the maximum voltage difference between the batteries of the energy storage system and the initial voltage difference protection threshold; wherein, obtaining the maximum voltage difference between the batteries of the energy storage system comprises: obtaining the highest voltage value and the lowest voltage value of the battery in the energy storage system; subtracting the highest voltage value from the lowest voltage value to obtain the maximum voltage difference; When the maximum pressure difference is greater than the initial pressure difference protection threshold, adjusting the pressure difference protection threshold from the initial pressure difference protection threshold to a target pressure difference protection threshold, wherein the target pressure difference protection threshold is greater than the initial pressure difference protection threshold; Controlling the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold; When the energy storage system is charging, adjusting the voltage difference protection threshold from the initial voltage difference protection threshold to the target voltage difference protection threshold includes: Obtaining a charging cut-off voltage value of the energy storage system; Subtracting the maximum voltage value from the charging cut-off voltage value to obtain a charging difference value; A target voltage difference protection threshold is obtained according to the charging difference and the initial voltage difference protection threshold.

2. The method according to claim 1, characterized in that: The obtaining of the target voltage difference protection threshold according to the charging difference and the initial voltage difference protection threshold comprises: A target voltage difference protection threshold is obtained by summing one half of the charging difference value and the initial voltage difference protection threshold.

3. The method according to claim 1, characterized in that: When the energy storage system is discharging, adjusting the pressure difference protection threshold from the initial pressure difference protection threshold to the target pressure difference protection threshold includes: Obtaining a discharge cut-off voltage value of the energy storage system; Subtracting the discharge cut-off voltage value from the minimum voltage value to obtain a discharge difference value; A target voltage difference protection threshold is obtained according to the discharge difference and the initial voltage difference protection threshold.

4. The method according to claim 3, characterized in that: The obtaining of the target voltage difference protection threshold according to the discharge difference and the initial voltage difference protection threshold comprises: A target voltage difference protection threshold is obtained by summing one half of the discharge difference value and the initial voltage difference protection threshold.

5. The method according to claim 1, characterized in that: When the energy storage system is charging, controlling the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold value includes: When the maximum voltage difference is not greater than the target voltage difference protection threshold, reducing the charging power of the energy storage system for charging, and performing balancing through the BMS of the energy storage system; When the maximum voltage difference is greater than the target voltage difference protection threshold, the energy storage system is controlled to stop charging, and the energy storage system is balanced through the BMS.

6. The method according to claim 5, characterized in that: The reducing the charging power of the energy storage system for charging includes: reducing the charging power to half for charging.

7. The method according to claim 1, characterized in that: When the energy storage system is discharging, controlling the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold value includes: When the maximum pressure difference is not greater than the target pressure difference protection threshold, reducing the discharge power of the energy storage system for discharge, and performing balancing through the BMS of the energy storage system; When the maximum pressure difference is greater than the target pressure difference protection threshold, the energy storage system is controlled to stop discharging, and the energy storage system is balanced through the BMS.

8. The method according to claim 7, characterized in that: The reducing the discharge power of the energy storage system for discharging includes: reducing the discharge power to half for discharging.

9. The method according to claim 5 or 7, characterized in that: Also includes: After the balancing is completed by the BMS of the energy storage system, the pressure difference protection threshold is adjusted from the target pressure difference protection threshold to the initial pressure difference protection threshold.

10. A charge and discharge control device for a series battery storage system, characterized in that: include: A parameter acquisition module, used to obtain the maximum voltage difference between the batteries of the energy storage system and the initial voltage difference protection threshold; wherein, obtaining the maximum voltage difference between the batteries of the energy storage system comprises: obtaining the highest voltage value and the lowest voltage value of the battery in the energy storage system; subtracting the highest voltage value from the lowest voltage value to obtain the maximum voltage difference; A threshold adjustment module is used to adjust the pressure difference protection threshold from the initial pressure difference protection threshold to the target pressure difference protection threshold when the maximum pressure difference is greater than the initial pressure difference protection threshold, and the target pressure difference protection threshold is greater than the initial pressure difference protection threshold; when the energy storage system is charging, the pressure difference protection threshold is adjusted from the initial pressure difference protection threshold to the target pressure difference protection threshold, including: Obtaining a charging cut-off voltage value of the energy storage system; Subtracting the maximum voltage value from the charging cut-off voltage value to obtain a charging difference value; Obtaining a target voltage difference protection threshold value according to the charging difference value and the initial voltage difference protection threshold value; The system control module is used to control the charging and discharging of the energy storage system according to the magnitude relationship between the maximum pressure difference and the target pressure difference protection threshold.

11. An energy storage system, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the method according to any one of claims 1 to 9.

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