Energy storage system and charging and discharging control method thereof

Abstract

The invention provides an energy storage system and a charging and discharging control method thereof. The energy storage system comprises a parallel operation device and at least two energy storage devices. The at least two energy storage devices are connected in parallel with a power grid through the parallel operation device, the parallel operation device is further connected with a load, the energy storage devices are in communication connection through a first communication bus, and the energy storage devices are in communication connection with the parallel operation device through a second communication bus; each energy storage device is configured to determine the number of all online energy storage devices at the current moment; obtaining charging and discharging parameters of all online energy storage devices at the current moment; acquiring a first electrical parameter of the power grid at the current moment and second electrical parameters of all loads at the current moment; and determining the charging power and the discharging power of each energy storage device at the current moment based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all the online energy storage devices, and carrying out charging and discharging, thereby reducing the condition of power grid overcurrent or power grid countercurrent.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of energy storage power supply, and specifically to an energy storage system and a charging and discharging control method thereof. Background Art

[0002] As people's understanding of energy storage equipment continues to deepen and outdoor travel activities become increasingly popular, the application areas of energy storage equipment are rapidly expanding. Faced with the increasing load power demand, the industry generally tends to adopt a solution of parallel output of multiple energy storage devices to efficiently meet the power supply of high-power loads.

[0003] At present, in parallel energy storage systems, multiple energy storage devices are connected in parallel to the power grid. However, in this process, the charging and discharging power regulation of energy storage devices often faces challenges, and it is difficult to quickly respond to fluctuations in load power or changes in the working state of the equipment. When the total output power of the parallel energy storage system exceeds the actual power demand of the user, the excess electric energy will flow back into the power grid, forming the so-called grid reverse flow phenomenon, which may not only disrupt the stable operation of the power grid system, but also pose a potential threat to the safety of the power grid. In addition, during the parallel charging and discharging process of energy storage devices, due to the existence of the current superposition effect, if there is a lack of fine control and balanced distribution of the charging and discharging current of each device, the total current flowing in the power grid can easily exceed its carrying capacity, resulting in the occurrence of grid overcurrent problems, which in turn buries safety hazards and affects the reliability and safety of the entire power system. Therefore, how to adjust the power of the parallel energy storage system to reduce grid overcurrent and grid reverse flow is of great significance for maintaining grid stability and ensuring power safety. Summary of the invention

[0004] The embodiment of the present application provides an energy storage system and a charging and discharging control method thereof, wherein each energy storage device can automatically calculate the charging and discharging power according to the power grid, the load and the parameters of each energy storage device, thereby reducing the occurrence of power grid overcurrent and power grid reverse current.

[0005] In a first aspect, an embodiment of the present application provides an energy storage system, which includes: a parallel device and at least two energy storage devices; the at least two energy storage devices are connected in parallel to a power grid through the parallel device, the parallel device is also connected to a load, each of the energy storage devices is communicatively connected to each other through a first communication bus, and each of the energy storage devices is communicatively connected to the parallel device through a second communication bus; each of the energy storage devices is configured to: determine the number of all online energy storage devices at a current moment; obtain the charging and discharging parameters of all the online energy storage devices at a current moment; obtain the first electrical parameter of the power grid at a current moment and the second electrical parameter of all the loads at a current moment; based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all the online energy storage devices, determine the charging power and discharging power of each of the energy storage devices at a current moment, and perform charging and discharging.

[0006] In one or more embodiments, based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all online energy storage devices, the charging power of each of the energy storage devices at the current moment is determined, including: based on the first electrical parameter and the second electrical parameter, determining the surplus power of the power grid at the current moment; based on the surplus power of the power grid and the charging and discharging parameters of each of the energy storage devices, determining the charging power of the energy storage device, wherein the charging and discharging parameters include the charging demand power of all online energy storage devices.

[0007] In one or more embodiments, for one of the online energy storage devices, the charging and discharging parameters of all the online energy storage devices at the current moment are obtained, including: obtaining the battery capacity of the energy storage device at the current moment, and determining the first required power of the energy storage device at the current moment based on the battery capacity; obtaining the battery operating temperature of the energy storage device at the current moment, and determining the second required power of the energy storage device at the current moment based on the battery operating temperature; and taking the minimum value of the first required power and the second required power as the charging required power of the energy storage device at the current moment.

[0008] In one or more embodiments, determining the first required power of the energy storage device at the current moment based on the battery capacity includes: determining a first constant based on the size of the battery capacity; obtaining the battery charge and discharge rate and the battery voltage of the energy storage device at the current moment; and determining the first required power based on the first constant, the battery charge and discharge rate, and the battery voltage.

[0009] In one or more embodiments, determining the second required power of the energy storage device at the current moment based on the battery operating temperature includes: determining a second constant based on the size of the battery operating temperature; obtaining the battery charge and discharge rate and the battery voltage of the energy storage device at the current moment; and determining the second required power based on the second constant, the battery charge and discharge rate, and the battery voltage.

[0010] In one or more embodiments, based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, the discharge power of each energy storage device at the current moment is determined, including: based on the charge and discharge parameters of all online energy storage devices, the discharge rate of each energy storage device at the current moment is determined, and the charge and discharge parameters include battery capacity; when the battery capacity of the energy storage device is greater than or equal to a power threshold, based on the second electrical parameter and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined; when the battery capacity of the energy storage device is less than the power threshold, based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined.

[0011] In one or more embodiments, based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined, including: based on the first electrical parameter and the second electrical parameter, obtaining the grid deficit power at the current moment; based on the grid deficit power and the discharge rate of the energy storage device, determining the discharge power of the energy storage device at the current moment.

[0012] In one or more embodiments, determining the number of all online energy storage devices at the current moment includes: obtaining the communication address of each of the energy storage devices at the current moment; and determining the number of all online energy storage devices at the current moment based on the communication address of each of the energy storage devices.

[0013] In one or more embodiments, determining the number of all online energy storage devices further includes: if at the current moment there are at least two energy storage devices with the same communication address, sending a contention queue address message and performing contention queue address until the communication address of any energy storage device is different from the communication address of other online energy storage devices.

[0014] In a second aspect, an embodiment of the present application further provides a charge and discharge control method for an energy storage system, which is applied to an energy storage system, wherein the energy storage system comprises: a parallel device and at least two energy storage devices; the at least two energy storage devices are connected in parallel to a power grid via the parallel device, the parallel device is also connected to a load, each of the energy storage devices is communicatively connected via a first communication bus, and each of the energy storage devices is communicatively connected to the parallel device via a second communication bus; the charge and discharge control method comprises: determining the number of all online energy storage devices at the current moment; obtaining the charge and discharge parameters of all the online energy storage devices at the current moment; obtaining the first electrical parameter of the power grid at the current moment and the second electrical parameter of all the loads at the current moment; based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all the online energy storage devices, determining the charging power and discharging power of each of the energy storage devices at the current moment, and performing charge and discharge.

[0015] The beneficial effects of the embodiments of the present application are as follows: in the energy storage system provided by the present application, each energy storage device can communicate with each other through the first communication bus, and the energy storage device and the parallel device can communicate with each other through the second communication bus. In this way, each energy storage device can obtain the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices through the communication bus, so that each energy storage device can automatically calculate its own charge and discharge power according to the above parameters, thereby efficiently responding to changes in load power and the working state of the energy storage device, reducing the occurrence of overcurrent and reverse current in the power grid, and in the energy storage system, each energy storage device works independently and will not interfere with each other, which reduces the complexity of the parallel energy storage system to a certain extent, and can timely update data and status in the event of a communication failure, thereby improving the anti-interference ability of the parallel energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0017] Figure 1 A structural block diagram of an energy storage system provided in an embodiment of the present application; Figure 2 A flow chart of a method for controlling charging and discharging of an energy storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element, or there can be one or more centered elements therebetween. When an element is described as "electrically connected" to another element, it can be directly connected to another element, or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0019] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items. In addition, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0020] In a first aspect, the present application provides an energy storage system, referring to Figure 1 The energy storage system includes: a parallel device 10 and at least two energy storage devices ( Figure 1 exemplarily including energy storage devices 1 to n, where n≥2). At least two energy storage devices are connected in parallel to the power grid 200 via a parallel device 10, and the parallel device 10 is also connected to the load 300. The energy storage devices are connected to each other via a first communication bus, and the energy storage devices are connected to the parallel device 10 via a second communication bus.

[0021] Energy storage equipment refers to an energy storage conversion device, which is composed of important components such as inverter, energy storage battery, battery management system, etc. The energy storage equipment can charge the energy storage battery through the mains, etc., and can supply power to the load 300. The energy storage equipment itself can work independently.

[0022] The load 300 refers to a device for consuming energy, and may include a refrigerator, a television, an electric tool, a smart terminal, and other equipment.

[0023] The parallel device 10 refers to a device that can control multiple energy storage devices to be connected in parallel, and can be connected to the power grid 200 and the load 300. The parallel device 10 increases the total power and total capacity of the multiple energy storage devices by connecting multiple energy storage devices in parallel. Specifically, in some implementations, the parallel device 10 has a power grid input interface, a load output interface and a parallel interface, the energy storage device has a parallel interface, the parallel interface of the energy storage device is electrically connected to the parallel interface of the parallel device 10 through a communication bus and an electrical connection line (live wire, neutral wire and ground wire), the power grid 200 is electrically connected to the power grid input interface through an electrical connection line (live wire, neutral wire and ground wire), and the load 300 is electrically connected to the load output interface through an electrical connection line (live wire, neutral wire and ground wire).

[0024] The first communication bus and the second communication bus can be CAN communication buses, so that each energy storage device and the parallel device 10 can communicate through the second communication bus, such as for transmitting the inverter voltage phase of the inverter, the completion status of the parallel (multiple energy storage devices in parallel), the load 300 current, the load 300 power and other data. Each energy storage device can communicate with each other through the first communication bus. For example, each energy storage device can transmit data for calculating the charging power and the discharging power on the first communication bus, such as: the battery capacity of the energy storage battery of the energy storage device at each moment, the battery operating temperature, and the charge and discharge identification data. Among them, the charge and discharge identification refers to the identification value indicating whether the energy storage device is in the charging state or the discharging state, for example: when the charge and discharge identification = 0, it means that the energy storage device is discharging, and when the charge and discharge identification = 1, it means that the energy storage device is charging.

[0025] In the energy storage system, each energy storage device is configured as follows: first, determine the number of all online energy storage devices at the current moment. Then, obtain the charge and discharge parameters of all online energy storage devices at the current moment. Next, obtain the first electrical parameter of the power grid at the current moment and the second electrical parameter of all loads at the current moment. Finally, based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, determine the charge power and discharge power of each energy storage device at the current moment, and perform charge and discharge.

[0026] The current moment refers to the moment at which the charging power and discharging power of the energy storage device are currently calculated. An online energy storage device refers to a device that has been connected to a parallel device and other energy storage devices, and can transmit and receive data with the parallel device and other energy storage devices in real time. The energy storage device can parse the message reported by each energy storage device on the first communication bus to find out the number of all online energy storage devices at the current moment.

[0027] The charge and discharge parameters of the energy storage device at the current moment refer to data that can be used to characterize the charge state and / or discharge state of the energy storage device at the current moment.

[0028] The first electrical parameter may include the maximum grid current and grid voltage, or include electrical parameters such as the maximum grid power. The maximum grid current refers to the maximum current value allowed to flow in the grid. The maximum grid current is usually determined based on the design of the grid, the rated current of the equipment, and safety factors, and is pre-set by the user. The grid voltage refers to the average value of the sum of the output voltages of the inverters of all online energy storage devices at the current moment. The maximum grid power is the value of the maximum grid current multiplied by the grid voltage.

[0029] The second electrical parameter may include load power, or electrical parameters such as load current and load voltage of each load connected to each energy storage reserve. Load power refers to the sum of the powers of all loads connected to all online energy storage devices. It is understandable that the load power can be calculated based on the load current and load voltage of each load.

[0030] The energy storage device can obtain the first electrical parameter and the second electrical parameter by communicating with the parallel device. After obtaining the above parameters, the energy storage device can determine the grid power based on the first electrical parameter, such as calculating the maximum grid power through the maximum grid current and the grid voltage, or directly obtaining the maximum grid power. Next, the load power is determined based on the second electrical parameter, such as calculating the load power through the load current and the load voltage, or directly obtaining the load power. Then, the current grid state is determined based on the maximum grid power and the load power, such as confirming that the grid is currently in a reverse current state or a grid overcurrent state, and the charging power or discharging power of the energy storage device is determined in combination with the charging and discharging parameters of all online energy storage devices under different grid states.

[0031] In the energy storage system provided in the present application, each energy storage device can communicate with each other through the first communication bus, and the energy storage device and the parallel device can communicate with each other through the second communication bus. In this way, each energy storage device can obtain the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all online energy storage devices through the communication bus, so that each energy storage device can automatically calculate its own charging power or discharging power at each moment according to the above parameters, thereby efficiently responding to changes in load power and the working state of the energy storage device, and reducing the occurrence of overcurrent and reverse current in the power grid. In addition, compared with the method of using the host to manage the charging and discharging of each energy storage device in the parallel energy storage system, each energy storage device can receive relevant data in time for charging and discharging management, solve the problems caused by communication delay in the master-slave parallel system, avoid unpredictable problems caused by the host disconnection, and improve the stability of the parallel energy storage system. Moreover, in this energy storage system, each energy storage device works independently and will not interfere with each other, which reduces the complexity of the parallel energy storage system to a certain extent, and can update data and status in time when a communication failure occurs, which improves the anti-interference ability of the parallel energy storage system. Furthermore, in the energy storage system, by classifying the data and transmitting them respectively on the first communication bus and the second communication bus, the data transmission path can be optimized, data conflicts and delays can be reduced, and communication efficiency can be improved.

[0032] In some embodiments, the charging power of each energy storage device at the current moment is determined based on the first electrical parameter, the second electrical parameter, and the charging and discharging parameters of all online energy storage devices, including: determining the grid surplus power at the current moment based on the first electrical parameter and the second electrical parameter. Determining the charging power of the energy storage device based on the grid surplus power and the charging and discharging parameters of each energy storage device, wherein the charging and discharging parameters include the charging demand power of all online energy storage devices.

[0033] After the energy storage device uses the first electrical parameter and the second electrical parameter to respectively determine the grid power and the load power, the grid power can be subtracted from the load power to obtain the grid surplus power.

[0034] The charging demand power refers to the maximum charging demand power of the energy storage device at the current moment. The charging demand power may be different at different moments. It is understandable that when the energy storage device is a discharging device, the charging demand power is 0.

[0035] Specifically, the charging power of the energy storage device at the current moment can be calculated based on the following formula: ; in, is the charging power of the x-th energy storage device at the current moment, is the maximum current of the power grid at the current moment, is the grid voltage at the current moment, is the load power at the current moment, is the grid surplus power at the current moment, is the charging power required by the x-th energy storage device at the current moment, y represents the charging power required by any energy storage device y among all energy storage devices currently online. It is the sum of the charging power requirements of all online energy storage devices at the current moment. Where 1≤x≤n, 1≤y≤n.

[0036] When the calculated charging power of the energy storage device is greater than 0, the energy storage device is charged according to the power size, and when the calculated charging power of the energy storage device is less than 0, the energy storage device is discharged according to the absolute value of the power.

[0037] In this embodiment, the grid surplus power is determined by the maximum grid power and the load power, and the charging power is dynamically adjusted in real time according to the grid surplus power, so as to ensure that the grid current does not exceed the maximum grid current, ensure that the grid does not over-current, avoid grid overload, cause line heating and thus cause fire.

[0038] It is worth noting that the charging power required for any energy storage device y among all the energy storage devices currently online is y is affected by the battery capacity and temperature of the energy storage device y at the current moment.

[0039] In some of the embodiments, for one of the online energy storage devices, the charging and discharging parameters of all the online energy storage devices at the current moment are obtained, including: obtaining the battery capacity of the energy storage device at the current moment, and determining the first required power of the energy storage device at the current moment based on the battery capacity; obtaining the battery operating temperature of the energy storage device at the current moment, and determining the second required power of the energy storage device at the current moment based on the battery operating temperature; and taking the minimum value of the first required power and the second required power as the charging required power of the energy storage device at the current moment.

[0040] Battery capacity refers to the remaining amount of electricity currently stored in the battery. The first power requirement refers to the maximum charging power requirement that the energy storage device can safely operate at the current remaining power. The second power requirement refers to the maximum charging power requirement that the energy storage device can safely operate at the current battery operating temperature.

[0041] After determining the first required power and the second required power, the energy storage device selects the smaller value as the charging required power of the energy storage device at the current moment to ensure the performance and safety of the energy storage device, and to ensure that the subsequently calculated charging power can avoid problems caused by exceeding the physical or temperature limits of the energy storage device during the charging process, thereby ensuring the stable operation and long-term reliability of the energy storage system.

[0042] In some embodiments, determining a first required power of an energy storage device at a current moment based on battery capacity includes: determining a first constant based on the size of the battery capacity; obtaining a battery charge and discharge rate and a battery voltage of the energy storage device at the current moment; and determining the first required power based on the first constant, the battery charge and discharge rate, and the battery voltage.

[0043] After obtaining the battery capacity, the first constant can be determined according to the first correspondence between the battery capacity and the first constant. The first correspondence stores the first constants corresponding to different battery capacities. The first correspondence can be pre-stored in the energy storage device. In this way, the first constant can be determined through the first correspondence. Specifically, when the battery capacity is less than 10%, the first constant is 0.2, when the battery capacity is greater than or equal to 10% and less than or equal to 90%, the first constant is 1, and when the battery capacity is greater than 90%, the first constant is 0.5.

[0044] The battery charge and discharge rate C refers to the ratio of the charge and discharge current to the rated capacity of the energy storage device within a specified time, that is, the charge and discharge rate = charge and discharge current / rated capacity. 1C represents the current intensity of the energy storage device when it is fully discharged in one hour. For example, if a battery with a nominal rated capacity of 100A·h is discharged at 1C intensity in one hour, then the current intensity of the energy storage device when it is fully discharged in one hour is 100A.

[0045] Specifically, the battery voltage can be measured by the battery voltage measurement unit of each energy storage device. After the battery voltage is obtained, the first required power can be calculated based on the following formula: ; in, is the first required power at the current moment, is the first constant, is the battery charge and discharge rate, is the battery voltage of the energy storage device at the current moment. That is, when the battery capacity is less than 10%, the first required power is P1=0.2C*BatVolt; when the battery capacity is greater than or equal to 10% and less than or equal to 90%, the first required power is P1=1C*BatVolt; when the battery capacity is greater than 90%, the first required power is P1=0.5C*BatVolt.

[0046] In the above embodiment, the first required power can be determined based on the battery capacity in the above manner.

[0047] In some embodiments, determining a second required power of the energy storage device at the current moment based on the battery operating temperature includes: determining a second constant based on the battery operating temperature; obtaining a battery charge and discharge rate and a battery voltage of the energy storage device at the current moment; and determining the second required power based on the second constant, the battery charge and discharge rate, and the battery voltage.

[0048] The battery operating temperature can be measured by a temperature measuring unit of the energy storage device that measures the battery operating temperature.

[0049] After obtaining the battery operating temperature, the second constant can be determined based on the second correspondence between the battery operating temperature and the second constant. The second correspondence stores the second constants corresponding to different battery operating temperatures. The second correspondence can be pre-stored in the energy storage device or energy storage system. In this way, the second constant can be determined through the second correspondence. Specifically, when the battery operating temperature is less than 10°C or greater than 45°C, the second constant is 0.2; when the battery operating temperature is within the range of [10°C, 45°C], the second constant is 1.

[0050] Specifically, after obtaining the battery charge and discharge rate and the battery voltage, the second required power can be calculated based on the following formula: ; in, is the second required power of the energy storage device at the current moment, is the first constant, is the battery charge and discharge rate, is the battery voltage of the energy storage device at the current moment. That is, when the battery operating temperature is less than 10°C or greater than 45°C, the second required power is P2=0.2C*BatVolt; when the battery operating temperature is greater than or equal to 10°C, or, when the battery operating temperature is less than or equal to 45°C, the second required power is P2=1C*BatVolt.

[0051] In the above embodiment, the second required power can be determined based on the battery operating temperature in the above manner.

[0052] In some embodiments, based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, the discharge power of each energy storage device at the current moment is determined, including: based on the charge and discharge parameters of all online energy storage devices, the discharge rate of each energy storage device at the current moment is determined, and the charge and discharge parameters include the battery capacity. When the battery capacity of the energy storage device is greater than or equal to the power threshold, the discharge power of the energy storage device at the current moment is determined based on the second electrical parameter and the discharge rate of the energy storage device. When the battery capacity of the energy storage device is less than the power threshold, the discharge power of the energy storage device at the current moment is determined based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device.

[0053] Battery capacity refers to the remaining amount of energy stored in the battery at the current moment. The discharge rate is calculated using the following formula: ; in, is the discharge rate of the x-th energy storage device at the current moment, is the battery capacity of the energy storage device at the current moment, is the battery capacity of any energy storage device y among all energy storage devices currently online, is the sum of the battery capacities of all online energy storage devices at the current moment, where 1≤x≤n, 1≤y≤n.

[0054] The power threshold refers to the maximum power of the energy storage device battery set by the user. When the battery capacity is greater than or equal to the power threshold, it indicates that the load connected to the energy storage device is completely powered by the corresponding energy storage device, and the power grid does not power the load. At this time, the discharge power is calculated based on the second electrical parameter of the load and the discharge rate. When the battery capacity is less than the power threshold, the load is completely powered by the power grid, and the discharge power is calculated based on the first electrical parameter, the second electrical parameter and the discharge rate.

[0055] In this embodiment, when the battery capacity of the energy storage device is greater than or equal to the power threshold, the energy storage device directly calculates the discharge power based on the second electrical parameter of the load and the discharge rate, which helps to ensure that the load is stably and adequately supplied with electricity. When the battery capacity of the energy storage device is less than the power threshold, the energy storage device calculates the discharge power based on the first electrical parameter of the power grid, the second electrical parameter of the load, and the discharge rate, comprehensively considering the conditions of the power grid and the load, and avoiding system instability or failure caused by energy shortages.

[0056] Moreover, when the parallel energy storage system is bypassed and loaded, each energy storage device can dynamically and in real time adjust the corresponding discharge power according to the battery capacity, load conditions and grid conditions, thereby reducing the reverse flow of the grid caused by sudden changes in load power.

[0057] Specifically, in some embodiments, when the battery capacity of the energy storage device is greater than or equal to the power threshold, the discharge power of the energy storage device can be calculated based on the following formula: ; in, is the discharge power of the x-th energy storage device at the current moment, is the load power at the current moment, is the discharge rate of the x-th energy storage device at the current moment.

[0058] Specifically, in other embodiments, when the battery capacity of the energy storage device is less than the power threshold, the power shortage of the power grid at the current moment is obtained based on the first electrical parameter and the second electrical parameter; based on the power shortage of the power grid and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined.

[0059] After the energy storage device uses the first electrical parameter and the second electrical parameter to respectively determine the grid power and the load power, the load power can be subtracted from the grid power to obtain the grid deficit power.

[0060] Then, the discharge power of the energy storage device at the current moment can be calculated based on the following formula: ; in, is the discharge power of the x-th energy storage device at the current moment, is the maximum current of the power grid at the current moment, is the grid voltage at the current moment, is the load power at the current moment, is the power shortage of the power grid at the current moment, is the discharge rate of the x-th energy storage device at the current moment.

[0061] In this embodiment, the power shortage of the power grid is determined by the maximum power of the power grid and the load power, and the size of the discharge power is dynamically adjusted in real time according to the power shortage of the power grid and the discharge rate, which can reduce the reverse flow of the power grid caused by the sudden change of the load power, thereby avoiding the phenomenon of power grid voltage fluctuation and frequency deviation caused by the reverse flow of the power grid, and increasing the power grid harmonics to cause power grid failure, thereby improving the stability of the power grid, and fully ensuring that the power grid current does not exceed its maximum current value when the energy storage parallel system is in the grid-connected state, and does not inject current into the power grid, thereby reducing the reverse flow of the power grid caused by the sudden change of the load power.

[0062] In some embodiments, determining the number of all online energy storage devices at the current moment includes: obtaining a communication address of each energy storage device at the current moment; and determining the number of all online energy storage devices at the current moment based on the communication address of each energy storage device.

[0063] Taking the first communication bus as the CAN communication bus as an example, each energy storage device has a CAN communication interface connected to the CAN communication bus, each individual energy storage device can receive messages on the CAN communication bus, and each individual energy storage device can send messages to the CAN communication bus, so as to achieve the monitoring of other devices sending CAN messages on the CAN communication bus by the energy storage device. Specifically, each individual energy storage device can obtain the communication address of the energy storage device by detecting the CAN message containing the communication address (such as the ID address) received on the CAN communication bus, and parsing it, that is, obtaining the communication address of other energy storage devices. After obtaining the communication address of each energy storage device, it can be determined whether the corresponding energy storage device is online. If the CAN message containing the communication address of the corresponding energy storage device cannot be monitored within a certain period of time, it is determined that the energy storage device is offline.

[0064] In this embodiment, the number of all online energy storage devices can be determined by monitoring messages on the first communication bus and analyzing the communication address of each energy storage device.

[0065] In some embodiments, determining the number of all online energy storage devices further includes: if at present there are at least two energy storage devices with the same communication address, sending a contention queueing message and performing contention queueing until the communication address of any energy storage device is different from the communication address of other online energy storage devices.

[0066] In an energy storage system, if two or more energy storage devices share the same communication address, communication conflicts will occur. This conflict will not only cause data loss, but may also cause the system to fall into an unstable state, affecting overall performance and reliability. Therefore, when a communication address conflict is detected, address rearrangement is required to ensure that each energy storage device has a unique communication address.

[0067] Specifically, in the first stage, when the energy storage device is powered on for the first time, or after the energy storage device completes the address arrangement, if the energy storage device parses out the same communication address from the messages containing the communication address sent by two different energy storage devices, or the energy storage device parses out the same communication address as itself from the messages containing the communication address sent by other energy storage devices, then the competitive address arrangement is triggered, and the energy storage device will send the competitive address arrangement message to the first communication bus, such as sending a parallel address trigger frame to the first communication bus. Then, the first stage continues for a first preset time (such as 3s) and then enters the second stage. In the second stage, after each energy storage device receives the competitive address arrangement message on the first communication bus, such as receiving the parallel address trigger frame, it compares its own device identification number (such as the product serial number of the device) with the device identification numbers of all energy storage devices stored on the bus in a comparison method to re-arrange the address, such as the device with the smallest identification number is at the smallest communication address, and the device with the largest identification number is at the largest communication address. Then, the second stage continues for a second preset time (such as 3s) before entering the third stage. In the third stage, each energy storage device uses the communication address after the second stage re-arrangement to communicate. It can be subsequently determined whether there are at least two energy storage devices with the same communication address until the communication address of any energy storage device is different from the communication address of other online energy storage devices. The first preset time and the second preset time can be determined based on the difference in power-on time of each energy storage device and the reporting cycle of the device identification number of each energy storage device, and it is not necessary to stick to the limitations in this embodiment.

[0068] In this embodiment, the above method can automatically trigger each energy storage device to rearrange its address when a communication address conflict occurs, thereby ensuring the uniqueness of the communication address of each energy storage device, which not only improves the working efficiency of the first communication bus, but also improves the stability of the first communication bus.

[0069] In a second aspect, the embodiment of the present application also provides a charge and discharge control method for an energy storage system, which is applied to an energy storage system, wherein the energy storage system comprises: a parallel device and at least two energy storage devices; at least two energy storage devices are connected in parallel to a power grid through the parallel device, and the parallel device is also connected to a load, and each energy storage device is connected to each other through a first communication bus, and each energy storage device is connected to the parallel device through a second communication bus. Figure 2 The charge and discharge control method includes the following steps: Step S10: Determine the number of all online energy storage devices at the current moment. Step S20: Obtain the charge and discharge parameters of all online energy storage devices at the current moment. Step S30: Obtain the first electrical parameter of the power grid at the current moment and the second electrical parameter of all loads at the current moment. Step S40: Based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, determine the charge power and discharge power of each energy storage device at the current moment, and perform charge and discharge.

[0070] For technical details not fully described in the charge and discharge control method of the energy storage system, please refer to the energy storage system provided in the above embodiments of the present application.

[0071] In the charge and discharge control method provided in the present application, each energy storage device can communicate with each other through the first communication bus, and the energy storage device and the parallel device can communicate with each other through the second communication bus. In this way, each energy storage device can obtain the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices through the communication bus, so that each energy storage device can automatically calculate its own charging power or discharging power at each moment according to the above parameters, thereby efficiently responding to changes in load power and the working state of the energy storage device, and reducing the occurrence of overcurrent and reverse current in the power grid. In addition, compared with the method of using the host to manage the charging and discharging of each energy storage device in the parallel energy storage system, each energy storage device can receive relevant data in time for charge and discharge management, solve the problem caused by communication delay in the master-slave parallel system, avoid unpredictable problems caused by the host disconnection, and improve the stability of the parallel energy storage system.

[0072] Furthermore, in the charge and discharge control method provided in the present application, each energy storage device can communicate with each other through the first communication bus, and the energy storage device and the parallel device can communicate with each other through the second communication bus. In this way, each energy storage device can obtain the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices through the communication bus, so that each energy storage device can automatically calculate its own charge and discharge power according to the above parameters. Compared with the method of using the host to manage the charge and discharge of each energy storage device in the parallel energy storage system, the present application can reduce the communication data on the parallel communication bus, and each energy storage device can receive relevant data in time for charge and discharge management, solve the problems caused by communication delay in the master-slave parallel system, such as the problem of grid current overcurrent and reverse flow, and avoid unpredictable problems caused by the host disconnection, thereby improving the stability of the parallel energy storage system. Moreover, in the energy storage system, each energy storage device works independently and will not interfere with each other, which reduces the complexity of the parallel energy storage system to a certain extent, and can update data and status in time when a communication failure occurs, thereby improving the anti-interference ability of the parallel energy storage system.

[0073] In some of the embodiments, based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, determining the charging power of each energy storage device at the current moment includes the following steps: Step S41A: Based on the first electrical parameter and the second electrical parameter, determining the grid surplus power at the current moment; Step S42A: Based on the grid surplus power and the charge and discharge parameters of each energy storage device, determining the charging power of the energy storage device, wherein the charge and discharge parameters include the charging demand power of all online energy storage devices.

[0074] In some of the embodiments, for one of the online energy storage devices, the charging and discharging parameters of all the online energy storage devices at the current moment are obtained, including the following steps: Step S21A: obtaining the battery capacity of the energy storage device at the current moment, and determining the first required power of the energy storage device at the current moment based on the battery capacity; Step S22A: obtaining the battery operating temperature of the energy storage device at the current moment, and determining the second required power of the energy storage device at the current moment based on the battery operating temperature; Step S23A: taking the minimum value of the first required power and the second required power as the charging required power of the energy storage device at the current moment.

[0075] In some of the embodiments, determining the first required power of the energy storage device at the current moment based on the battery capacity includes the following steps: Step S211A: determining a first constant based on the battery capacity; Step S212A: obtaining the battery charge and discharge rate and the battery voltage of the energy storage device at the current moment; Step S213A: determining the first required power based on the first constant, the battery charge and discharge rate and the battery voltage.

[0076] In some of the embodiments, determining the second required power of the energy storage device at the current moment based on the battery operating temperature includes the following steps: Step S221A: determining a second constant based on the battery operating temperature; Step S222A: obtaining the battery charge and discharge rate and the battery voltage of the energy storage device at the current moment; Step S223A: determining the second required power based on the second constant, the battery charge and discharge rate and the battery voltage.

[0077] In some of the embodiments, based on the first electrical parameter, the second electrical parameter and the charge and discharge parameters of all online energy storage devices, the discharge power of each energy storage device at the current moment is determined, including the following steps: Step S41B: Based on the charge and discharge parameters of all online energy storage devices, the discharge rate of each energy storage device at the current moment is determined, and the charge and discharge parameters include the remaining battery capacity; Step S42B: When the battery capacity of the energy storage device is greater than or equal to the power threshold, based on the second electrical parameter and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined; Step S43B: When the battery capacity of the energy storage device is less than the power threshold, based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device, the discharge power of the energy storage device at the current moment is determined.

[0078] In some of the embodiments, based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device, determining the discharge power of the energy storage device at the current moment includes the following steps: Step S431B: Based on the first electrical parameter and the second electrical parameter, obtaining the grid shortfall power at the current moment; Step S432B: Based on the grid shortfall power and the discharge rate of the energy storage device, determining the discharge power of the energy storage device at the current moment.

[0079] In some embodiments, determining the number of all online energy storage devices at the current moment includes the following steps: Step S11: obtaining the communication address of each energy storage device at the current moment; Step S12: determining the number of all online energy storage devices at the current moment based on the communication address of each energy storage device.

[0080] In some embodiments, determining the number of all online energy storage devices also includes step S13: if there are at least two energy storage devices with the same communication address at the current moment, sending a contention queue address message and performing contention queue address until the communication address of any energy storage device is different from the communication address of other online energy storage devices.

[0081] It should be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An energy storage system, characterized in that: include: Parallel equipment and at least two energy storage devices; The at least two energy storage devices are connected in parallel to the power grid via the parallel device, the parallel device is also connected to the load, the energy storage devices are communicatively connected to each other via a first communication bus, and the energy storage devices are communicatively connected to the parallel device via a second communication bus; Each of the energy storage devices is configured as: Determine the number of all online energy storage devices at the current moment; Obtaining the charging and discharging parameters of all online energy storage devices at the current moment; Acquire a first electrical parameter of the power grid at a current moment and a second electrical parameter of all the loads at a current moment; Based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all online energy storage devices, the charging power and discharging power of each of the energy storage devices at the current moment are determined, and charging and discharging are performed.

2. The energy storage system according to claim 1, characterized in that: Determining the charging power of each of the energy storage devices at a current moment based on the first electrical parameter, the second electrical parameter, and the charging and discharging parameters of all online energy storage devices, including: Determining the surplus power of the power grid at the current moment based on the first electrical parameter and the second electrical parameter; Based on the surplus power of the power grid and the charging and discharging parameters of each of the energy storage devices, the charging power of the energy storage device is determined, wherein the charging and discharging parameters include the charging demand power of all online energy storage devices.

3. The energy storage system according to claim 2, characterized in that: For one of the online energy storage devices, obtaining the charge and discharge parameters of all the online energy storage devices at the current moment includes: Acquire the battery capacity of the energy storage device at the current moment, and determine the first required power of the energy storage device at the current moment based on the battery capacity; Acquire a battery operating temperature of the energy storage device at the current moment, and determine a second required power of the energy storage device at the current moment based on the battery operating temperature; The minimum value between the first required power and the second required power is used as the charging required power of the energy storage device at the current moment.

4. The energy storage system according to claim 3, characterized in that: The determining, based on the battery capacity, a first required power of the energy storage device at the current moment includes: Determining a first constant based on the battery capacity; Obtaining the battery charge and discharge rate and battery voltage of the energy storage device at the current moment; The first required power is determined according to the first constant, the battery charge and discharge rate, and the battery voltage.

5. The energy storage system according to claim 3, characterized in that: The determining the second required power of the energy storage device at the current moment based on the battery operating temperature includes: Determining a second constant based on the operating temperature of the battery; Obtaining the battery charge and discharge rate and battery voltage of the energy storage device at the current moment; The second required power is determined according to the second constant, the battery charge and discharge rate, and the battery voltage.

6. The energy storage system according to claim 1, characterized in that: Based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all online energy storage devices, determining the discharge power of each of the energy storage devices at the current moment includes: Determine the discharge rate of each of the energy storage devices at the current moment based on the charge and discharge parameters of all the online energy storage devices, wherein the charge and discharge parameters include battery capacity; When the battery capacity of the energy storage device is greater than or equal to the power threshold, determining the discharge power of the energy storage device at the current moment based on the second electrical parameter and the discharge rate of the energy storage device; When the battery capacity of the energy storage device is less than the power threshold, the discharge power of the energy storage device at the current moment is determined based on the first electrical parameter, the second electrical parameter and the discharge rate of the energy storage device.

7. The energy storage system according to claim 6, characterized in that: Determining the discharge power of the energy storage device at a current moment based on the first electrical parameter, the second electrical parameter, and the discharge rate of the energy storage device includes: Based on the first electrical parameter and the second electrical parameter, obtaining the power shortage of the power grid at the current moment; Based on the power shortage of the power grid and the discharge ratio of the energy storage device, the discharge power of the energy storage device at the current moment is determined.

8. The energy storage system according to claim 1, characterized in that: Determine the number of all online energy storage devices at the current moment, including: Obtaining the communication address of each of the energy storage devices at the current moment; Based on the communication address of each of the energy storage devices, the number of all online energy storage devices at the current moment is determined.

9. The energy storage system according to claim 8, characterized in that: The determining the number of all online energy storage devices further includes: If at the current moment there are at least two energy storage devices with the same communication address, a contention queue message is sent and the contention queue is performed until the communication address of any energy storage device is different from the communication address of other online energy storage devices.

10. A charge and discharge control method for an energy storage system, characterized in that: Applied to an energy storage system, the energy storage system comprising: a parallel device and at least two energy storage devices; The at least two energy storage devices are connected in parallel to the power grid via the parallel device, the parallel device is also connected to the load, the energy storage devices are communicatively connected to each other via a first communication bus, and the energy storage devices are communicatively connected to the parallel device via a second communication bus; The charge and discharge control method comprises: Determine the number of all online energy storage devices at the current moment; Obtaining the charging and discharging parameters of all online energy storage devices at the current moment; Acquire a first electrical parameter of the power grid at a current moment and a second electrical parameter of all the loads at a current moment; Based on the first electrical parameter, the second electrical parameter and the charging and discharging parameters of all online energy storage devices, the charging power and discharging power of each of the energy storage devices at the current moment are determined, and charging and discharging are performed.

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