Battery electric quantity detection method and energy storage system

Abstract

The invention discloses a battery electric quantity detection method and an energy storage system. The method comprises the following steps: determining the first battery capacity of an energy storage battery, wherein the first battery capacity is the residual capacity of the energy storage battery at a first moment; the battery capacity change of the energy storage battery is determined, the battery capacity change is used for indicating the capacity change of the battery rated capacity of the energy storage battery at the second moment relative to the battery rated capacity of the energy storage battery at the first moment, the battery rated capacity is the maximum value of the electric charge quantity capable of being stored by the energy storage battery, and the first moment is earlier than the second moment; performing electric quantity compensation on the first battery capacity according to the battery capacity change to determine a second battery capacity of the energy storage battery, wherein the second battery capacity is the residual capacity of the energy storage battery at the second moment; and determining the charge state of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery. According to the scheme, the problem that the state of charge estimation of the energy storage battery is inaccurate due to the temperature change of the energy storage battery is solved.

Description

Technical Field

[0001] The present invention relates to the field of new energy technologies, and particularly to a method for detecting battery power and an energy storage system. Background Art

[0002] With the development of renewable energy, the demand for energy storage systems has increased, and the state of charge (SOC) of a battery directly affects the performance of an energy storage system. The SOC estimation is affected by changes in parameters such as battery capacity and internal resistance, which affects the estimation accuracy. In related solutions, the estimation of the energy storage battery capacity is mostly relatively traditional, and basically adopts the method of directly looking up a table according to a temperature-capacity table. However, the SOC calculation in the energy storage field is different from that in the fields of mobile phones and electric vehicles. Especially in the energy storage field, the computing resources and energy consumption are strictly limited, making some complex calculation methods that are feasible in the fields of mobile phones and electric vehicles difficult to be applied here. Moreover, the energy storage field faces more extreme situations, such as drastic temperature changes, which may cause significant fluctuations in battery performance and affect the accuracy of SOC calculation. Especially in cold regions, due to special climatic conditions, during the static state and the charging and discharging process of the battery under extreme temperature conditions, the temperature change range within a short period of time is often large. During this process, both the ambient temperature of the battery and its own operating temperature will change significantly. Relying on looking up a table according to the temperature-capacity table to calculate the battery capacity will introduce a large error. In contrast, the charging and discharging of mobile phones and electric vehicles are relatively stable and relatively predictable. Therefore, the SOC battery power estimation methods in the fields of mobile phones and electric vehicles are difficult to meet the requirements of SOC calculation in the energy storage field, seriously affecting the accurate estimation of the battery SOC and thus reducing the overall performance of the energy storage system. Summary of the Invention

[0003] The present invention provides a method for detecting battery power and an energy storage system to solve the problem that inaccurate estimation of the state of charge of an energy storage battery is caused by temperature changes of the energy storage battery.

[0004] According to one aspect of the present invention, there is provided a method for detecting battery power, wherein the method includes:

[0005] Determine a first battery capacity of an energy storage battery, where the first battery capacity is the remaining capacity of the energy storage battery at a first moment;

[0006] Determine a battery capacity change of the energy storage battery, where the battery capacity change is used to indicate the capacity change of the rated battery capacity of the energy storage battery at a second moment relative to the rated battery capacity at the first moment, and the rated battery capacity is the maximum value of the electric charge amount that the energy storage battery can store, and the first moment is earlier than the second moment;

[0007] Determine the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the change in the battery capacity, where the second battery capacity is the remaining capacity of the energy storage battery at the second moment;

[0008] Determine the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery.

[0009] According to another aspect of the present invention, there is provided an energy storage system, including: at least one battery module; at least one battery management system, where the at least one battery management system corresponds to the at least one battery module one by one, the battery management system is electrically connected to the corresponding battery module, and the battery management system is used to execute the battery power detection method described in any embodiment of the present invention.

[0010] The technical solution of the embodiment of the present invention can accurately capture the dynamic change of the energy storage battery capacity at different moments after being affected by temperature by determining the capacity change that occurs between the rated battery capacity of the energy storage battery at the first moment and the rated battery capacity of the energy storage battery at the second moment, where the rated battery capacity is the maximum value of the electric charge that the battery can store; based on the capacity change that occurs between the rated battery capacity of the energy storage battery at the first moment and the rated battery capacity of the energy storage battery at the second moment, perform charge compensation on the remaining capacity of the energy storage battery at the first moment to determine the remaining capacity of the energy storage battery at the second moment, fully considering the dynamic characteristics of the battery capacity itself, which can solve the interference of temperature factors on the assessment of the remaining capacity of the energy storage battery, provide a basis for the performance assessment of the energy storage battery, make the calculation of the remaining capacity at the second moment more in line with the actual situation of the battery, and greatly improve the accuracy of the remaining capacity estimation compared with directly calculating the remaining capacity without considering the impact of temperature on the remaining capacity of the energy storage battery. Calculate the state of charge of the energy storage battery at the second moment by using the accurately determined remaining capacity of the energy storage battery at the second moment, making the assessment of the state of charge of the energy storage battery more reliable.

[0011] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0013] Figure 1It is a flowchart of a method for detecting battery power according to an embodiment of the present invention;

[0014] Figure 2 It is a flowchart of another method for detecting battery power according to an embodiment of the present invention;

[0015] Figure 3 It is a timing diagram adopted during the detection process of battery power according to an embodiment applicable to the present invention;

[0016] Figure 4 It is another timing diagram adopted during the detection process of battery power according to an embodiment applicable to the present invention. Detailed implementation manners

[0017] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0019] Figure 1 An embodiment of the present invention provides a flowchart of a method for detecting battery power. This embodiment is applicable to the situation of estimating the state of charge of an energy storage battery when the temperature of the energy storage battery changes. This method can be configured to be executed on an energy storage system, which can be implemented in the form of hardware and / or software, and the energy storage system can be configured in any electronic device with network communication functions.

[0020] As Figure 1 shown, the method for detecting battery power in this embodiment includes the following processes:

[0021] S110. Determine the first battery capacity of the energy storage battery, where the first battery capacity is the remaining capacity of the energy storage battery at the first moment.

[0022] The energy storage battery can be a battery with an energy storage function that converts chemical energy into electrical energy. The energy storage battery can convert electrical energy into chemical energy and store it in the battery during charging, and can convert the stored chemical energy back into electrical energy for release when discharging is required. The energy storage battery can be a device for storing electrical energy, which can release the stored electrical energy for use by a load when needed, and is widely used in fields such as renewable energy power generation, power grid energy storage, and electric vehicles. The energy storage battery can be applied to various electronic devices, electric vehicles, renewable energy power generation systems, etc. to achieve effective storage and utilization of electrical energy. For example, the energy storage battery can include, but is not limited to, the following types of batteries: lead-acid batteries, lithium-ion batteries, flow batteries, sodium-sulfur batteries, nickel-cadmium batteries, and nickel-metal hydride batteries.

[0023] The first battery capacity can be the remaining capacity of the energy storage battery at the first moment. The remaining capacity refers to the amount of electric charge that can still be used and is stored inside the energy storage battery. The remaining capacity can be the amount of electricity that remains after a certain period of use or discharge of the energy storage battery and can still be stored or used. For example, the remaining capacity can be represented by Qremain, which is the amount of electricity that has not been consumed in the energy storage battery and is used to evaluate the available degree and endurance ability of the energy storage battery.

[0024] Optionally, at least one of the ampere-hour integration method, the open-circuit voltage method, and the battery model-based method can be used to estimate the remaining capacity of the energy storage battery at the first moment. Among them, the ampere-hour integration method calculates the remaining capacity by measuring and integrating the battery charge and discharge current in real time. There is a certain correspondence between the open-circuit voltage of the battery and the remaining capacity. After the battery is left standing for a period of time (usually several hours to ensure a stable state inside the battery), its open-circuit voltage is measured, and then the corresponding remaining capacity is found through a pre-established open-circuit voltage-remaining capacity relationship curve or table. The battery model-based method calculates the remaining capacity at the first moment by establishing a battery model and comprehensively considering various factors such as the electrochemical characteristics, temperature effect, and charge and discharge history of the battery, and by inputting various parameters of the battery and the charge and discharge data before the first moment, and using the battery model.

[0025] S120. Determine the change in the battery capacity of the energy storage battery. The change in the battery capacity is used to indicate the change in the rated battery capacity of the energy storage battery at the second moment relative to the rated battery capacity at the first moment. The rated battery capacity is the maximum amount of electric charge that the energy storage battery can store, and the first moment is earlier than the second moment.

[0026] The rated capacity of a battery can be the maximum value of the electric charge that an energy storage battery can accommodate and store under established standards or ideal conditions (such as set temperature, charging rate, etc.). The rated capacity of a battery can reflect the energy storage capacity of the energy storage battery. The rated capacity of a battery can be expressed in units of ampere-hour (Ah) or milliampere-hour (mAh). For example, an energy storage battery marked with a rated capacity of 100 Ah can store an electric charge of 100 Ah when charged from a fully discharged state to a fully charged state under ideal charging conditions. Regarding the rated capacity of an energy storage battery, from the perspective of the working principle of the energy storage battery, the energy storage battery stores and releases electrical energy through internal chemical reactions, and the degree of progress of the chemical reaction determines the amount of electric charge stored by the energy storage battery.

[0027] As the number of uses increases and time goes by, the electrode materials inside the battery will gradually undergo irreversible changes, such as the loss of active substances and the damage of the electrode structure, resulting in a gradual decrease in the maximum value of the electric charge that the battery can store. The change in the battery temperature at different times will affect the rated capacity of the energy storage battery. Too high or too low temperature will affect the internal chemical reactions, material properties, and internal resistance of the battery, thereby changing the maximum value of the electric charge that the battery can store. If the energy storage battery undergoes a temperature change process between the first moment and the second moment, it may have a greater impact on the structure and performance of the energy storage battery, resulting in a change in the rated capacity of the battery.

[0028] The first moment and the second moment can be two different time points selected during the monitoring of the energy storage battery. Among them, the first moment and the second moment can be the measurement time points of two adjacent estimations of the state of charge of the battery respectively; or, the first moment and the second moment can be two adjacent time points before and after the energy storage battery experiences a specific working condition respectively; or, the first moment and the second moment can be two representative time points selected to detect the performance change of the energy storage battery over a period of time.

[0029] The change in battery capacity can be the capacity change of the energy storage battery at the second moment relative to the rated capacity of the energy storage battery at the first moment due to the temperature change of the energy storage battery during the use of the energy storage battery. The change in battery capacity can specifically be the difference or change in the maximum value of the electric charge that can be stored obtained by comparing the maximum value of the electric charge that the energy storage battery can store at the second moment with the maximum value of the electric charge that the energy storage battery can store at the first moment.

[0030] By comparing the rated battery capacity of the energy storage battery at different times, the change in the maximum amount of electric charge that the energy storage battery can store from the first time to the second time can be intuitively reflected. Based on the rated battery capacity of the energy storage battery at the first time, comparing the rated battery capacity of the energy storage battery at the second time can directly reflect the increase or decrease in the battery's storage capacity, providing key reference information for evaluating the remaining capacity of the energy storage battery at the second time. That is, through the changes in the rated battery capacity at multiple different times, the trend of the remaining capacity of the energy storage battery over time can be inferred.

[0031] As an optional but non-limiting implementation solution, determining the change in the battery capacity of the energy storage battery includes, but is not limited to, the following steps A1 - A2:

[0032] Step A1: Determine the first temperature and the second temperature of the energy storage battery. The first temperature is the battery temperature of the energy storage battery at the first time, and the second temperature is the battery temperature of the energy storage battery at the second time.

[0033] Step A2: When the first temperature and the second temperature are different, determine the first rated battery capacity and the second rated battery capacity of the energy storage battery according to the first temperature and the second temperature, and determine the change in the battery capacity of the energy storage battery according to the first rated battery capacity and the second rated battery capacity of the energy storage battery. The change in the battery capacity is determined according to the absolute value of the difference between the first rated battery capacity and the second rated battery capacity. The first rated battery capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the first time, and the second rated battery capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the second time.

[0034] The first temperature and the second temperature can be the battery temperatures corresponding to the energy storage battery at the first time and the second time respectively. The battery temperature is an important factor affecting the performance of the energy storage battery and will change with factors such as the charge and discharge process of the battery, the ambient temperature, and the heat dissipation characteristics of the battery itself.

[0035] Optionally, a temperature sensor is set inside the energy storage battery or in the battery management system. The temperature sensor can include the following thermocouples, thermistors, or integrated temperature sensors, which are used to directly measure the temperature of the energy storage battery. For example, the resistance value of a thermistor changes with temperature, and by measuring its resistance value, the corresponding temperature value can be calculated, enabling real-time and accurate acquisition of the temperature information inside the battery. And / or, the temperature sensor is installed on the surface of the energy storage battery housing or on the heat dissipation components of the battery pack to indirectly measure the temperature of the energy storage battery. Furthermore, the temperature sensor can be used to obtain the battery temperature of the energy storage battery at the first time and the battery temperature of the energy storage battery at the second time.

[0036] Optionally, the battery temperature of the energy storage battery at the first moment and the battery temperature of the energy storage battery at the second moment can be estimated through the terminal voltage of the energy storage battery. There is a certain relationship between the terminal voltage and the temperature of the energy storage battery. At different temperatures, the charge and discharge voltage platforms of the energy storage battery will be different. By establishing a correspondence relationship model between the terminal voltage and the temperature of the energy storage battery, the battery temperature of the energy storage battery can be estimated using the measured terminal voltage of the energy storage battery.

[0037] Optionally, the battery temperature of the energy storage battery at the first moment and the battery temperature of the energy storage battery at the second moment can be estimated through the internal resistance of the energy storage battery. The internal resistance of the energy storage battery also changes with temperature. Generally speaking, the lower the temperature, the greater the internal resistance of the energy storage battery. By measuring the AC internal resistance or DC internal resistance of the energy storage battery and combining it with the relationship curve between the internal resistance and the temperature, the temperature of the energy storage battery can be estimated.

[0038] The first battery rated capacity can be the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the first moment. That is to say, the first battery rated capacity is the maximum amount of electric charge that the energy storage battery can hold under the condition of this first temperature. The second battery rated capacity can be the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the second moment. Among them, the charge storage capacity of the energy storage battery is affected by temperature. At different temperatures, the chemical reaction activity and ion migration speed inside the energy storage battery are different, resulting in different maximum amounts of electric charge that the energy storage battery can store.

[0039] Optionally, determining the first battery rated capacity and the second battery rated capacity of the energy storage battery according to the first temperature and the second temperature may include the following steps: obtaining a battery capacity calculation model associated with the energy storage battery, where the battery capacity model is used to record the mapping relationship between the battery temperature of the energy storage battery and the maximum amount of electric charge that the energy storage battery can store at the corresponding battery temperature; inputting the first temperature and the second temperature of the energy storage battery into the battery capacity calculation model respectively to obtain the first battery rated capacity and the second battery rated capacity of the energy storage battery in sequence.

[0040] Optionally, the fitting relationship between the battery temperature of the energy storage battery recorded by the battery capacity calculation model associated with the energy storage battery and the maximum amount of electric charge that the energy storage battery can store at the corresponding battery temperature is shown by the following calculation formula: Qmax = Z0 + Z1*T + Z2*T^2 +... + Zn*T^n, where Z0 - Zn are fitting coefficients, T is the battery temperature, with the unit of °C, and it is required that T is an integer, and Qmax is the maximum amount of electric charge that the energy storage battery can store at the corresponding battery temperature.

[0041] The change in battery capacity of the energy storage battery from the first moment to the second moment is determined according to the absolute value of the difference between the first battery rated capacity and the second battery rated capacity. Since the energy storage battery has different charge storage capabilities at different temperatures, by comparing the maximum charge amounts that the energy storage battery can store at its respective temperatures at the first moment and the second moment, that is, the first battery rated capacity and the second battery rated capacity, the change in the battery capacity of the energy storage battery with temperature can be determined. Calculating the absolute value of the difference between the two is to obtain a non - negative value to accurately reflect the magnitude of the battery capacity change. For example, if the first battery rated capacity is 50 Ah and the second battery rated capacity is 45 Ah, then the battery capacity change is |50 - 45| = 5 Ah, indicating that during the process of the energy storage battery from the first moment to the second moment, due to temperature change, the maximum charge amount that the energy storage battery can store has changed by 5 Ah.

[0042] Exemplarily, taking the first moment as T1 and the second moment as T2 as an example, the first battery rated capacity of the energy storage battery at the first moment is Qmax1, and the second battery rated capacity Qmax2 of the energy storage battery at the second moment. Define LFD as the change in the battery capacity of the energy storage battery from the first moment to the second moment, which is a positive value. If T1 > T2, indicating that the energy storage battery cools down from the first moment to the second moment, then LFD = Qmax1 - Qmax2 can be configured; otherwise, indicating that the energy storage battery heats up from the first moment to the second moment, then LFD = Qmax2 - Qmax1 can be configured.

[0043] As an optional but non - limiting implementation solution, determining the change in the battery capacity of the energy storage battery includes, but is not limited to, the following steps:

[0044] Determine the first temperature and the second temperature of the energy storage battery. The first temperature is the battery temperature of the energy storage battery at the first moment, and the second temperature is the battery temperature of the energy storage battery at the second moment; determine the change in the battery capacity of the energy storage battery according to the temperature difference between the first temperature and the second temperature and the preset capacity change amount. The preset capacity change amount indicates the change amount caused by a unit temperature change of the energy storage battery to the battery capacity of the energy storage battery.

[0045] In the process of monitoring and analyzing the performance of an energy storage battery, the first temperature refers to the battery temperature presented by the energy storage battery at the first moment, and the second temperature refers to the battery temperature corresponding to the energy storage battery at the second moment. By calculating the difference between the first temperature and the second temperature, the temperature fluctuation range experienced by the energy storage battery during the period from the first moment to the second moment can be clearly grasped. The preset capacity change indicates the change in the battery capacity of the energy storage battery caused by a unit temperature change of the energy storage battery. The preset capacity change can be pre-configured based on a large amount of experimental data and in-depth research on the characteristics of the energy storage battery. For example, through repeated experimental measurements, for every 1°C increase or decrease in the energy storage battery, its battery capacity will increase or decrease by a preset value correspondingly, and this preset value is the battery capacity change of the energy storage battery.

[0046] Based on the above two, when determining the battery capacity change of the energy storage battery, first calculate the exact temperature difference between the first temperature and the second temperature, and then perform a mathematical operation on this temperature difference and the preset capacity change. Specifically, if the temperature difference is positive, it indicates that the temperature of the energy storage battery rises, and multiplying the temperature difference by the preset capacity change, the result obtained is the increase in battery capacity caused by the temperature rise; if the temperature difference is negative, it means that the temperature of the energy storage battery drops, and similarly multiplying the absolute value of the temperature difference by the preset capacity change, the result obtained is the decrease in battery capacity caused by the temperature drop. In this way, the battery capacity change of the energy storage battery under different temperature condition changes can be determined more accurately.

[0047] As an optional but not limited implementation solution, determining the battery capacity change of the energy storage battery includes, but is not limited to, the following steps:

[0048] Determine the first temperature and the second temperature of the energy storage battery. The first temperature is the battery temperature of the energy storage battery at the first moment, and the second temperature is the battery temperature of the energy storage battery at the second moment; in the case where it is detected that the first temperature and the second temperature are not the same, then perform the operation of determining the battery capacity change of the energy storage battery; in the case where it is detected that the first temperature and the second temperature are the same, do not perform the operation of determining the battery capacity change of the energy storage battery.

[0049] S130. Determine the second battery capacity of the energy storage battery by performing a power compensation on the first battery capacity according to the battery capacity change. The second battery capacity is the remaining capacity of the energy storage battery at the second moment.

[0050] The maximum amount of electric charge that an energy storage battery can store changes with temperature. For example, at higher temperatures, the maximum amount of electric charge that the energy storage battery can store increases, while at lower temperatures, the maximum amount of electric charge that the energy storage battery can store decreases. After the maximum amount of electric charge that the energy storage battery can store changes, the remaining capacity of the energy storage battery will also be adjusted accordingly. When determining the remaining capacity of the energy storage battery at the first moment, considering that the temperature of the energy storage battery changes from the first moment to the second moment, resulting in a change in the rated capacity of the battery from the first moment to the second moment. Therefore, without considering other factors that cause changes in the remaining capacity of the energy storage battery, the calculation of the remaining capacity of the energy storage battery at the second moment needs to consider the influence of the temperature change from the first moment to the second moment.

[0051] To more accurately evaluate the remaining capacity of the energy storage battery at the second moment, the change in the rated capacity of the battery caused by the temperature change from the first moment to the second moment of the energy storage battery is introduced, and the remaining capacity of the energy storage battery at the first moment is compensated and adjusted according to the change in the battery capacity of the energy storage battery. If the change in the battery capacity of the energy storage battery increases, then based on the change in the battery capacity of the energy storage battery, a partial amount of electric charge is added to the first battery capacity to obtain the remaining capacity of the energy storage battery at the second moment; if the change in the battery capacity of the energy storage battery decreases, based on the change in the battery capacity of the energy storage battery, a partial amount of electric charge is subtracted from the first battery capacity to obtain the remaining capacity of the energy storage battery at the second moment.

[0052] By adopting the above method, the change in the battery capacity of the energy storage battery is used to further achieve the compensation of the electric charge for the change in the battery capacity caused by the temperature change of the remaining capacity of the energy storage battery at the first moment, which can eliminate the interference of the temperature factor on the battery capacity evaluation, so as to obtain the remaining capacity at the second moment considering the change of the battery capacity with temperature.

[0053] S140. Determine the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery.

[0054] The second battery capacity can refer to the remaining capacity of the energy storage battery at the second moment, which reflects the amount of electric charge that can be used and stored inside the battery of the energy storage battery at the second moment. The state of charge (SOC) can be a parameter used to describe the current charging state of the energy storage battery, which can be expressed as a percentage, ranging from 0% (fully discharged) to 100% (fully charged), and intuitively reflects the relative relationship between the remaining electric charge in the energy storage battery and the total battery capacity, that is, the ratio of the electric charge stored by the energy storage battery under certain conditions to the total electric charge when the energy storage battery is fully charged.

[0055] As an optional but not limiting implementation, determining the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery includes, but is not limited to, the following steps:

[0056] Determine the state of charge of the energy storage battery at the second moment according to the ratio between the second battery capacity of the energy storage battery and the second battery rated capacity, where the second battery rated capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the second moment.

[0057] The technical solution of the embodiment of the present invention can accurately capture the dynamic change of the energy storage battery capacity at different moments after being affected by temperature by determining the capacity change that occurs between the battery rated capacity at the first moment and the battery rated capacity at the second moment of the energy storage battery. The battery rated capacity is the maximum amount of electric charge that the battery can store. Based on the capacity change that occurs between the battery rated capacity at the first moment and the battery rated capacity at the second moment of the energy storage battery, the remaining capacity of the energy storage battery at the first moment is compensated for electricity to determine the remaining capacity of the energy storage battery at the second moment, fully considering the dynamic characteristics of the battery capacity itself. It can solve the interference of temperature factors on the evaluation of the remaining capacity of the energy storage battery, provide a basis for the performance evaluation of the energy storage battery, make the calculation of the remaining capacity at the second moment more in line with the actual situation of the battery, and greatly improve the accuracy of the remaining capacity estimation compared with directly calculating the remaining capacity without considering the influence of temperature on the remaining capacity of the energy storage battery. Using the accurately determined remaining capacity of the energy storage battery at the second moment to calculate the state of charge of the energy storage battery at the second moment makes the evaluation of the state of charge of the energy storage battery more reliable.

[0058] Figure 2 It is a schematic flowchart of another method for detecting battery power provided by the embodiment of the present invention. The technical solution of this embodiment further optimizes the process of compensating the first battery capacity for electricity according to the battery capacity change to determine the second battery capacity of the energy storage battery in the foregoing embodiment on the basis of the technical solution of the foregoing embodiment. This embodiment can be combined with each optional solution in one or more of the foregoing embodiments.

[0059] As Figure 2 shown, the method for detecting battery power in this embodiment may include the following process:

[0060] S210. Determine the first battery capacity of the energy storage battery, where the first battery capacity is the remaining capacity of the energy storage battery at the first moment.

[0061] Optionally, the first battery capacity is specifically the remaining capacity of the energy storage battery obtained by compensating the third battery capacity at the first moment. The third battery capacity is the remaining capacity of the energy storage battery at the third moment, and the third moment is the moment adjacent to and before the first moment. The first moment and the third moment can be two different time points selected during the monitoring of the energy storage battery. Among them, the first moment and the third moment can be the measurement time points of two adjacent estimations and measurements of the state of charge of the battery respectively; or, the first moment and the third moment can be two adjacent time points before and after the energy storage battery experiences a specific working condition respectively; or, the first moment and the third moment can be two representative time points selected to detect the performance change of the energy storage battery over a period of time.

[0062] S220. Determine the change in the battery capacity of the energy storage battery. The change in the battery capacity is used to indicate the change in the rated battery capacity of the energy storage battery at the second moment relative to the rated battery capacity at the first moment. The rated battery capacity is the maximum amount of electric charge that the energy storage battery can store, and the first moment is earlier than the second moment.

[0063] S230. When the energy storage battery cools down during the transition from the first moment to the second moment, determine the second capacity limit value of the energy storage battery. The second capacity limit value is used to indicate the lower limit value of the remaining capacity that the energy storage battery should reach at the second moment.

[0064] When the energy storage battery cools down during the transition from the first moment to the second moment, it means that between the first moment and the second moment of the energy storage battery, the battery temperature of the energy storage battery decreases. The battery temperature of the energy storage battery is affected by various factors, such as environmental temperature changes (low-temperature environment), the battery's own heat dissipation process, and heat generation changes during the battery charging and discharging process. For example, in winter, the energy storage battery outdoors may have its battery temperature drop from 20°C to 5°C from the first moment to the second moment due to the decrease in environmental temperature.

[0065] The second capacity limit value is used to indicate the lower limit value of the remaining capacity that the energy storage battery should reach at the second moment. The second capacity limit value is used to ensure that even under adverse conditions such as cooling, although the change in the rated battery capacity will cause a change in the remaining capacity of the energy storage battery, the energy storage battery still maintains a certain amount of power reserve, that is, the lower limit value of the remaining capacity that the energy storage battery should display.

[0066] Low temperature can have a negative impact on the performance of energy storage batteries, such as reducing the charge and discharge efficiency of energy storage batteries and decreasing the available capacity of energy storage batteries. By setting a second capacity limit, when the energy storage battery cools down, its remaining capacity can be ensured to be maintained at a level that can guarantee the normal charge and discharge functions of the battery. For example, when the battery temperature decreases, the internal chemical reaction rate slows down and ion migration is blocked, which may lead to a reduction in the actual available capacity. If no capacity limit is set, over-discharging of the energy storage battery may damage the internal structure of the battery and affect the battery life, while the second capacity limit can provide a protection boundary for the energy storage battery to avoid over-discharging.

[0067] Optionally, the second capacity limit is determined based on the second battery rated capacity and the state of charge limit. The second battery rated capacity is the maximum amount of electric charge that the energy storage battery can store at the temperature at the second moment, and the state of charge limit is the lower limit of the state of charge that the energy storage battery needs to reach.

[0068] S240. Determine the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit. The second battery capacity is the remaining capacity of the energy storage battery at the second moment.

[0069] Optionally, determining the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit includes the following steps: comparing the calculated battery capacity change with the second capacity limit, where the second capacity limit is the lower limit of the remaining capacity that the energy storage battery should display under the temperature conditions at the second moment; when the difference between the first battery capacity and the battery capacity change is not greater than the second capacity limit, it is considered that the remaining capacity of the energy storage battery at the second moment has reached the second capacity limit and no further compensation can be continued; when the difference between the first battery capacity and the battery capacity change is greater than the second capacity limit, select to use the battery capacity change to perform charge compensation on the first battery capacity to determine the second battery capacity of the energy storage battery.

[0070] As an optional but non-limiting implementation solution, determining the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit includes but is not limited to the following steps:

[0071] When it is detected that the second battery capacity is greater than the sum of the battery capacity change and the second capacity limit, the difference between the first battery capacity of the energy storage battery and the battery capacity change is determined as the second battery capacity of the energy storage battery; when it is detected that the second battery capacity is not greater than the sum of the battery capacity change and the second capacity limit, the second capacity limit is determined as the second battery capacity of the energy storage battery.

[0072] When it is detected that the second battery capacity of the energy storage battery is greater than the sum of the battery capacity change and the second capacity limit, it means that according to the current calculation or estimation, the remaining capacity of the energy storage battery at the second moment is relatively high, which can meet the lower limit requirement specified by the second capacity limit, and there is still a certain margin. In this case, the difference between the first battery capacity of the energy storage battery and the battery capacity change is determined as the second battery capacity of the energy storage battery. Because the first battery capacity is the capacity in the initial state, subtracting the battery capacity change from the first moment to the second moment can obtain the actual remaining capacity of the battery at the second moment. This remaining capacity has a certain surplus on the basis of meeting the lower limit requirement, which conforms to the reasonable estimation of the battery remaining capacity under the current conditions.

[0073] When it is detected that the second battery capacity of the energy storage battery is not greater than the sum of the battery capacity change and the second capacity limit, it indicates that the remaining capacity of the energy storage battery at the second moment is relatively low, and it may just reach or be lower than the lower limit requirement specified by the second capacity limit. This situation may be caused by excessive capacity decline due to battery temperature change, low initial capacity itself, and other factors. In this case, in order to ensure that the energy storage battery can meet the basic performance, safety, and subsequent power consumption requirements, the second capacity limit is determined as the second battery capacity of the energy storage battery to ensure that the battery can at least display the preset minimum remaining capacity standard.

[0074] As an optional but non-limiting implementation solution, after determining the second battery capacity of the energy storage battery by compensating the power of the first battery capacity according to the battery capacity change and the second capacity limit, it further includes but is not limited to the following steps:

[0075] Determine the second offset of the energy storage battery. The second offset is the cumulative result generated by at least one power compensation deviation of the energy storage battery up to the second moment. The power compensation deviation is used to indicate the deviation generated between the first type of remaining capacity and the second type of remaining capacity in the case where the remaining capacity of the energy storage battery decreases due to the cooling of the energy storage battery. The first type of remaining capacity is the compensated remaining capacity of the energy storage battery obtained after power compensation when the remaining capacity of the energy storage battery decreases, and the second type of remaining capacity is the actual remaining capacity of the energy storage battery when the remaining capacity of the energy storage battery decreases.

[0076] As an optional but non-limiting implementation solution, determining the second offset of the energy storage battery includes but is not limited to the following steps B1 - B2:

[0077] Step B1: When it is detected that the second battery capacity is greater than the sum of the battery capacity change and the second capacity limit, determine the first offset of the energy storage battery as the second offset of the energy storage battery. The first offset of the energy storage battery is the cumulative result of at least one charge compensation deviation of the energy storage battery up to the first moment before the second moment.

[0078] Step B2: When it is detected that the second battery capacity is not greater than the sum of the battery capacity change and the second capacity limit, determine the second offset of the energy storage battery according to the first offset of the energy storage battery and the first battery capacity compensation deviation. The first battery capacity compensation deviation is used to indicate the charge compensation deviation determined according to the battery capacity change, the second capacity limit, and the first capacity limit in the case where the remaining capacity of the energy storage battery is lost due to temperature drop when the energy storage battery transitions from the first moment to the second moment. The first capacity limit is used to indicate the lower limit value of the remaining capacity that the energy storage battery should reach at the first moment.

[0079] The first offset can be the cumulative result of at least one charge compensation deviation of the energy storage battery up to the first moment before the second moment. The charge compensation deviation can be the difference from the theoretical value generated during each charge compensation operation due to reasons such as calculation errors and battery characteristic changes, and the cumulative sum of these differences is the first offset.

[0080] The first battery capacity compensation deviation can be the charge compensation deviation determined comprehensively based on the battery capacity change, the second capacity limit, and the first capacity limit when the remaining capacity of the energy storage battery is lost due to temperature drop when the energy storage battery transitions from the first moment to the second moment. The first capacity limit is the lower limit value of the remaining capacity that the energy storage battery should reach at the first moment, similar to the corresponding value of the second capacity limit at the first moment.

[0081] When the second battery capacity is greater than the sum of the battery capacity change and the second capacity limit, it indicates that the remaining capacity of the energy storage battery at the second moment is relatively sufficient, which can not only meet the requirements of the second capacity limit but also exceed the range defined by the sum of the battery capacity change and the second capacity limit. At this time, directly determine the first offset of the energy storage battery as the second offset. Because the current battery capacity is in good condition, there is no need to adjust the offset, and the previously accumulated first offset can be continued to be used. It can be understood that when the battery capacity situation is optimistic, the continuity of the cumulative result of the previous charge compensation deviation is maintained, and no new adjustment factors are introduced to maintain the stability and coherence of the calculation.

[0082] When the second battery capacity is not greater than the sum of the battery capacity change and the second capacity limit, it indicates that the remaining capacity of the energy storage battery at the second moment is relatively low and may be close to or lower than the second capacity limit. This situation may be due to factors such as temperature drop, which cause a large loss of the energy storage battery capacity, or there are deviations in the previous power compensation, resulting in an unsatisfactory actual remaining capacity of the battery. In this case, the second offset needs to be determined based on the first offset of the energy storage battery and the first battery capacity compensation deviation. Specifically, it is necessary to comprehensively consider the previously accumulated power compensation deviation (i.e., the first offset) and the power compensation deviation determined when the remaining capacity is lost due to temperature drop this time (the first battery capacity compensation deviation).

[0083] By adding the two deviation values, a new offset is obtained, that is, the second offset. The first battery capacity compensation deviation is the power compensation deviation determined by subtracting the first capacity limit from the sum of the battery capacity change and the second capacity limit. In this way, when the battery capacity state is poor, the previously accumulated power compensation deviation is corrected and adjusted to accurately reflect the actual power compensation situation of the battery and provide more reliable data support for subsequent battery management operations. For example, if the first offset is a positive deviation (the previous power compensation is generally too much), and the first battery capacity compensation deviation is a negative deviation (more power should be supplemented due to temperature drop this time but was not made up before), then when calculating the second offset, it is necessary to comprehensively consider the magnitude relationship between the two, and obtain a new offset that can balance the influence of the two through a suitable algorithm to optimize the subsequent power compensation strategy.

[0084] Exemplarily, define the first moment as T1, the second moment as T2, the first battery rated capacity of the energy storage battery at the first moment as Qmax1, the second battery rated capacity Qmax2 of the energy storage battery at the second moment, the first battery capacity as Qremain1, the second battery capacity as Qremain2, the first capacity limit as Qmin1, the second capacity limit as Qmin2, the first offset as Qdebt1, the second offset as Qdebt2, and LFD as the battery capacity change of the energy storage battery from the first moment to the second moment, which is a positive value. If T1>T2, it indicates that the energy storage battery has a temperature drop from the first moment to the second moment, then LFD = Qmax1 - Qmax2 can be configured; otherwise, it indicates that the energy storage battery has a temperature rise from the first moment to the second moment, then LFD = Qmax2 - Qmax1 can be configured. See Figure 3 , when it is detected that Qremain1 > LFD + Qmin2 is satisfied, Qremain2 = Qremain1 - LFD, and Qdebt2 = Qdebt1; See Figure 4, when it is detected that Qremain1 <= LFD + Qmin2 is satisfied, Qremain2 = Qmin2, and Qdebt2 = Qdebt1 + LFD + Qmin2 - Qremain1, where Qremain1 >= Qmin1.

[0085] S250. Determine the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery.

[0086] As an optional but non-limiting implementation solution, to determine the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the battery capacity change, the following steps C1 - C2 are further included:

[0087] Step C1. When the energy storage battery heats up from the first moment to the second moment, determine the first offset of the energy storage battery. The first offset of the energy storage battery is the cumulative result generated by at least one charge compensation deviation of the energy storage battery at the first moment before the second moment; the charge compensation deviation is used to indicate the deviation generated between the first type of remaining capacity and the second type of remaining capacity when the remaining capacity of the energy storage battery decreases due to the cooling of the energy storage battery; the first type of remaining capacity is the compensated remaining capacity of the energy storage battery obtained after charge compensation when the remaining capacity of the energy storage battery decreases, and the second type of remaining capacity is the actual remaining capacity of the energy storage battery when the remaining capacity of the energy storage battery decreases.

[0088] Step C2. According to the first offset and the battery capacity change, perform charge compensation on the first battery capacity to determine the second battery capacity of the energy storage battery.

[0089] Optionally, to perform charge compensation on the first battery capacity according to the first offset and the battery capacity change to determine the second battery capacity of the energy storage battery, the following steps are included: When the first offset is not greater than the battery capacity change, determine the second battery capacity of the energy storage battery according to the first battery capacity, the battery capacity change, and the first offset. The second battery capacity is the result of the difference processing after summing the first battery capacity and the battery capacity change and then subtracting the first offset; when the first offset is greater than the battery capacity change, determine the first battery capacity as the second battery capacity of the energy storage battery.

[0090] Optionally, after determining the second battery capacity of the energy storage battery by compensating the power of the first battery capacity according to the first offset and the battery capacity change, the following steps are further included: when the first offset is greater than the battery capacity change, determining the difference between the first offset and the battery capacity change as the second offset of the energy storage battery, where the second offset is the cumulative result of at least one power compensation deviation of the energy storage battery up to the second moment; when the first offset is not greater than the battery capacity change, configuring the second offset of the energy storage battery as a preset value, and the preset value is 0.

[0091] In the actual application of the SOC algorithm, there are significant scenario differences between the energy storage field and mobile phones and electric vehicles. From the perspective of computing resources, energy storage products are essentially different from mobile phones and electric vehicles. Compared with mobile phones and electric vehicles, the computing resources of energy storage products are extremely limited, their chip computing power is low, and considering the energy consumption problem, energy storage products do not frequently interact with the cloud platform (i.e., the background data management system), which means that large models and complex algorithms applicable to mobile phones and electric vehicles are difficult to implement in the energy storage field and do not meet the need for efficient algorithms in the energy storage system to meet the requirements of SOC calculation accuracy. From the charging and discharging scenarios, the differences between energy storage products and mobile phones and electric vehicles are also obvious. When mobile phones and electric vehicles are charging, they rely on a stable power grid for power supply, and the charging conditions are relatively certain, making the SOC calibration during the charging process relatively easy. However, energy storage products prefer to use the PV (photovoltaic charging) method. Due to the continuous change of sunlight intensity, the charging current may not only fluctuate violently but also often have a very small charging current, greatly increasing the difficulty of SOC calibration. In the discharging scenario, the random connection and disconnection of household loads lead to frequent fluctuations in the discharging current of energy storage products, further increasing the complexity of SOC calibration.

[0092] Furthermore, the influence of temperature conditions on the SOC algorithm cannot be ignored. The usage scenarios of mobile phones are mostly in indoor environments with stable temperatures, or the temperature is kept suitable because they are placed in warm clothes. Electric vehicles are equipped with a perfect thermal management system that can effectively maintain the stability of the operating temperature. In sharp contrast, energy storage systems are usually installed outdoors. Considering the energy consumption problem, in non-essential situations (such as forced charging when the battery is low or the SOC is low), the energy storage system will not actively heat up; and due to the product's sealing requirements, there is generally no air duct for heat dissipation, which causes the temperature of the battery cells to fluctuate greatly during the operation of the energy storage system, and the impact on the SOC estimation of the energy storage battery is more obvious.

[0093] In addition, for energy storage cushion points, the differences in the cell types of energy storage batteries also affect the application of the SOC algorithm. Generally, NCM (ternary lithium) cells are mostly used in mobile phones and electric vehicles, while LFP (lithium iron phosphate) cells are commonly used in energy storage products considering both price and safety. Compared with NCM cells, LFP cells have the significant feature of a longer third power conversion stage of the working voltage. During the third power conversion stage, the charge and discharge voltage changes very little, which makes it impossible to achieve full-process SOC calibration like NCM cells, and has a more serious impact on the SOC estimation of energy storage batteries.

[0094] In response to these special requirements in the energy storage field, this solution innovatively proposes a SOC calculation algorithm based on temperature compensation. In terms of limited computing resources and energy consumption, it has extremely low computational complexity, enabling smooth operation even when the chip computing power of energy storage products is insufficient, without the support of powerful computing resources. At the same time, it has extremely low energy consumption during operation, meeting the strict requirements for energy consumption control in the energy storage field, avoiding the high energy consumption problems caused by frequent data interaction with the cloud platform or running complex algorithms, greatly improving the energy utilization efficiency of the energy storage system, and reducing the long-term operation cost. Moreover, in response to the current situation of more extreme cases in the energy storage field, it shows excellent adaptability. In a high-temperature environment, it can automatically compensate and adjust the SOC calculation according to the significant increase in the cell temperature to ensure that the accuracy of SOC estimation is not affected by high temperature. When encountering low temperature, it can also flexibly correct the calculation parameters according to the characteristics of battery performance changes at low temperature to maintain the accuracy of SOC estimation.

[0095] The technical solution of the embodiment of the present invention can accurately capture the dynamic changes of the energy storage battery capacity at different times after being affected by temperature by determining the capacity change that occurs between the battery rated capacity at the first moment and the battery rated capacity at the second moment of the energy storage battery. The battery rated capacity is the maximum value of the electric charge that the battery can store. Based on the capacity change that occurs between the battery rated capacity at the first moment and the battery rated capacity at the second moment of the energy storage battery, the remaining capacity of the energy storage battery at the first moment is compensated for electricity to determine the remaining capacity of the energy storage battery at the second moment, fully considering the dynamic characteristics of the battery capacity itself. It can solve the interference of temperature factors on the evaluation of the remaining capacity of the energy storage battery, provide a basis for the performance evaluation of the energy storage battery, make the calculation of the remaining capacity at the second moment more in line with the actual situation of the battery, and greatly improve the accuracy of the remaining capacity estimation compared with directly calculating the remaining capacity without considering the impact of temperature on the remaining capacity of the energy storage battery. Using the accurately determined remaining capacity of the energy storage battery at the second moment to calculate the state of charge of the energy storage battery at the second moment makes the evaluation of the state of charge of the energy storage battery more reliable.

[0096] According to an embodiment of the present invention, the process described above with reference to the flowchart can be applied to an energy storage system. For example, an embodiment of the present invention includes an energy storage system, which includes: at least one battery module; at least one battery management system, where the at least one battery management system corresponds one-to-one with the at least one battery module, the battery management system is electrically connected to the corresponding battery module, and the battery management system is used to include program code for executing the battery power detection method shown in the flowchart.

[0097] In such an embodiment, the energy storage system provided by the present application is applicable to various application scenarios, such as the grid-connected power generation energy storage field, the off-grid photovoltaic energy storage field (used to supply power to electrical equipment in households, RVs, and yachts), the wind energy storage power generation field, the electric equipment field, etc. Specifically, it can be determined according to the actual application scenario and will not be limited here. The following will take the off-grid photovoltaic energy storage field as an example for illustration. For other application scenarios, it is basically similar and will not be elaborated.

[0098] In the off-grid photovoltaic energy storage application scenario, a complete photovoltaic energy storage system at least includes a photovoltaic power generation system, a power conversion system, an energy storage system, and an electrical consumption system. The photovoltaic power generation system is composed of a plurality of solar panels connected in series and parallel, and is used to convert solar energy into electrical energy. The power conversion system injects the electrical energy generated by the photovoltaic power generation system into the energy storage system for storage. The electrical consumption system then adapts the electrical energy stored in the energy storage system to the power required by the electrical equipment. The aforementioned power conversion system can usually be implemented by a DC / DC converter with an MPPT function, and the electrical consumption system can usually be implemented by a DC / DC converter and a DC / AC converter. Here, the energy storage system will be mainly introduced. The energy storage system is usually composed of connecting multiple battery packs to each other. Using the battery packs in series can increase the output voltage of the battery pack, and using the battery packs in parallel can obtain a larger battery capacity. Therefore, in order to obtain an energy storage system with a target voltage level and capacity, users will connect multiple battery packs in series and parallel with each other to obtain a high-voltage and large-capacity energy storage system for energy storage and power supply. In addition, for convenient centralized and unified control, each battery pack in the energy storage system is usually also provided with a communication interface, and the battery packs can communicate with each other through methods such as CAN bus, RS485 bus, and RS232 bus. Currently, with the further development of the new energy industry and the extension of application scenarios, higher requirements are put forward for the various performances of the energy storage system, including system stability and consistency, waterproof and dustproof, and safety level, etc.

[0099] In an optional but non-limiting implementation manner, the solution of the present application also provides a photovoltaic power generation system, which includes: a photovoltaic power generation component, a controller, and the energy storage system according to any one of the above embodiments; the photovoltaic power generation component is used to convert solar energy into direct current electrical energy; the controller is used to store the direct current electrical energy in the energy storage system.

[0100] It should be understood that the various forms of processes shown above can be used, with steps reordered, added or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and no limitation is imposed herein.

[0101] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting battery power, characterized in that, The method includes: Determine a first battery capacity of the energy storage battery, where the first battery capacity is the remaining capacity of the energy storage battery at a first moment; Determine a battery capacity change of the energy storage battery, where the battery capacity change is used to indicate the capacity change of the rated battery capacity of the energy storage battery at a second moment relative to the rated battery capacity at the first moment. The rated battery capacity is the maximum amount of electric charge that the energy storage battery can store, and the first moment is earlier than the second moment; Perform charge compensation on the first battery capacity according to the battery capacity change to determine a second battery capacity of the energy storage battery, where the second battery capacity is the remaining capacity of the energy storage battery at the second moment; Determine the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery.

2. The method according to claim 1, wherein Determine the battery capacity change of the energy storage battery, including: Determine a first temperature and a second temperature of the energy storage battery, where the first temperature is the battery temperature of the energy storage battery at the first moment, and the second temperature is the battery temperature of the energy storage battery at the second moment; When the first temperature and the second temperature are different, determine a first rated battery capacity and a second rated battery capacity of the energy storage battery according to the first temperature and the second temperature, and determine the battery capacity change of the energy storage battery according to the first rated battery capacity and the second rated battery capacity of the energy storage battery. The battery capacity change is determined according to the absolute value of the difference between the first rated battery capacity and the second rated battery capacity. The first rated battery capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the first moment, and the second rated battery capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the second moment.

3. The method according to claim 1, wherein Perform charge compensation on the first battery capacity according to the battery capacity change to determine the second battery capacity of the energy storage battery, including: When the energy storage battery cools down from the first moment to the second moment, determine a second capacity limit of the energy storage battery, where the second capacity limit is used to indicate the lower limit value of the remaining capacity that the energy storage battery should reach at the second moment; Perform charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit to determine the second battery capacity of the energy storage battery.

4. The method according to claim 3, wherein Perform charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit to determine the second battery capacity of the energy storage battery, including: When it is detected that the second battery capacity is greater than the sum of the battery capacity change and the second capacity limit, determine the difference between the first battery capacity of the energy storage battery and the battery capacity change as the second battery capacity of the energy storage battery; When it is detected that the second battery capacity is not greater than the sum of the battery capacity change and the second capacity limit, determine the second capacity limit as the second battery capacity of the energy storage battery.

5. The method according to claim 3, wherein After performing charge compensation on the first battery capacity according to the battery capacity change and the second capacity limit to determine the second battery capacity of the energy storage battery, it further includes: Determine a second offset of the energy storage battery, where the second offset is the cumulative result of at least one charge compensation deviation of the energy storage battery up to a second moment; the charge compensation deviation is used to indicate the deviation generated between a first type of remaining capacity and a second type of remaining capacity when the remaining capacity of the energy storage battery is lost due to the cooling of the energy storage battery; the first type of remaining capacity is the compensated remaining capacity of the energy storage battery obtained after charge compensation when the remaining capacity of the energy storage battery is lost, and the second type of remaining capacity is the actual remaining capacity of the energy storage battery after the remaining capacity of the energy storage battery is lost.

6. The method according to claim 5, wherein Determining the second offset of the energy storage battery includes: When it is detected that the second battery capacity is greater than the sum of the battery capacity change and the second capacity limit, determine the first offset of the energy storage battery as the second offset of the energy storage battery, where the first offset of the energy storage battery is the cumulative result of at least one charge compensation deviation of the energy storage battery up to a first moment before the second moment; When it is detected that the second battery capacity is not greater than the sum of the battery capacity change and the second capacity limit, determine the second offset of the energy storage battery according to the first offset of the energy storage battery and the first battery capacity compensation deviation; the first battery capacity compensation deviation is used to indicate the charge compensation deviation determined according to the battery capacity change, the second capacity limit, and the first capacity limit when the remaining capacity of the energy storage battery is lost due to the cooling of the energy storage battery from the first moment to the second moment; the first capacity limit is used to indicate the lower limit of the remaining capacity that the energy storage battery should reach at the first moment.

7. The method according to claim 1, characterized in that Determining the second battery capacity of the energy storage battery by performing charge compensation on the first battery capacity according to the battery capacity change includes: When the energy storage battery heats up from the first moment to the second moment, determine the first offset of the energy storage battery, where the first offset of the energy storage battery is the cumulative result of at least one charge compensation deviation of the energy storage battery up to a first moment before the second moment; the charge compensation deviation is used to indicate the deviation generated between a first type of remaining capacity and a second type of remaining capacity when the remaining capacity of the energy storage battery is lost due to the cooling of the energy storage battery; the first type of remaining capacity is the compensated remaining capacity of the energy storage battery obtained after charge compensation when the remaining capacity of the energy storage battery is lost, and the second type of remaining capacity is the actual remaining capacity of the energy storage battery after the remaining capacity of the energy storage battery is lost; Perform charge compensation on the first battery capacity according to the first offset and the battery capacity change to determine the second battery capacity of the energy storage battery.

8. The method according to claim 7, wherein Performing charge compensation on the first battery capacity according to the first offset and the battery capacity change to determine the second battery capacity of the energy storage battery includes: When the first offset is not greater than the change in battery capacity, determine the second battery capacity of the energy storage battery according to the first battery capacity, the change in battery capacity, and the first offset; the second battery capacity is the result of the difference processing after summing the first battery capacity and the change in battery capacity and then subtracting the first offset; When the first offset is greater than the change in battery capacity, determine the first battery capacity as the second battery capacity of the energy storage battery.

9. The method according to claim 8, wherein After determining the second battery capacity of the energy storage battery by compensating the power of the first battery capacity according to the first offset and the change in battery capacity, it further includes: When the first offset is greater than the change in battery capacity, determine the difference between the first offset and the change in battery capacity as the second offset of the energy storage battery, and the second offset is the cumulative result generated by at least one power compensation deviation of the energy storage battery up to the second moment; When the first offset is not greater than the change in battery capacity, configure the second offset of the energy storage battery as a preset value, and the preset value is 0.

10. The method according to claim 1, characterized in that, Determine the state of charge of the energy storage battery at the second moment according to the second battery capacity of the energy storage battery, including: Determine the state of charge of the energy storage battery at the second moment according to the ratio between the second battery capacity of the energy storage battery and the second battery rated capacity, and the second battery rated capacity is the maximum amount of electric charge that the energy storage battery can store at the battery temperature at the second moment.

11. An energy storage system, characterized in that, It includes: At least one battery module; at least one battery management system, the at least one battery management system corresponds to the at least one battery module one by one, the battery management system is electrically connected to the corresponding battery module, and the battery management system is used to execute the battery power detection method described in any one of claims 1-10.

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