Energy storage control method and device and energy storage system

Abstract

The application discloses an energy storage control method and device and an energy storage system. The energy storage system comprises a first energy storage unit and a second energy storage unit, and the first energy storage unit and the second energy storage unit are connected to a load. The second energy storage unit is a lithium ion battery. The energy storage control method comprises the following steps: detecting a load current in real time; determining an energy storage unit for supplying power to the load and controlling an output current of the energy storage unit according to the load current, an upper limit value of an output current of the second energy storage unit and a load current change rate, so that the second energy storage unit limits power output and the first energy storage unit responds to load power change in real time. The first energy storage unit and the second energy storage unit are combined, the second energy storage unit constantly outputs power according to requirements, the first energy storage unit changes the output power to respond to the load power change in real time, the real-time response to the load power change is realized, the economy of energy storage is realized, the two energy storage units are used to supply power, and the overall operation life of the energy storage system is prolonged.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and more specifically, to an energy storage control method, device, and energy storage system. Background Technology

[0002] While conventional lithium-ion batteries offer a price advantage, their charge / discharge rates and cycle life are relatively limited. Frequent charging and discharging, or charging and discharging at high rates, can negatively impact the lifespan of lithium-ion batteries.

[0003] There is currently no effective solution to the problem that frequent charging and discharging or high-rate charging and discharging of lithium-ion batteries affects their service life. Summary of the Invention

[0004] This invention provides an energy storage control method, device, and energy storage system to at least solve the problem in the prior art where frequent charging and discharging or high-rate charging and discharging affects the service life of lithium-ion batteries.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide an energy storage control method. The energy storage system includes: a first energy storage unit and a second energy storage unit, both of which are connected to a load. The second energy storage unit is a lithium-ion battery. The energy storage control method includes:

[0006] Real-time load current detection;

[0007] Based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, the energy storage unit that supplies power to the load is determined and the output current of the energy storage unit is controlled so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time.

[0008] Optionally, based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, determining the energy storage unit that supplies power to the load and controlling the output current of that energy storage unit includes:

[0009] If the load current is less than or equal to the upper limit of the output current of the second energy storage unit, then the energy storage unit that supplies power to the load is determined and the output current of the energy storage unit is controlled according to the load current change rate and the preset change rate.

[0010] Optionally, based on the load current change rate and a preset change rate, determining the energy storage unit that supplies power to the load and controlling the output current of the energy storage unit includes:

[0011] Detect the rate of change of load current within a preset time period;

[0012] If the load current change rate is less than the preset change rate, then it is determined that the second energy storage unit will supply power to the load, and the output current of the second energy storage unit will be controlled to be constant at the load current;

[0013] If the load current change rate is greater than or equal to the preset change rate, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the first current, and the output current of the first energy storage unit is controlled to be the load current minus the first current, wherein the first current is less than or equal to the upper limit value of the output current of the second energy storage unit.

[0014] Optionally, based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, determining the energy storage unit that supplies power to the load and controlling the output current of that energy storage unit includes:

[0015] If the load current is greater than the upper limit of the output current of the second energy storage unit, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the upper limit of the output current, and the output current of the first energy storage unit is controlled to be the load current minus the upper limit of the output current.

[0016] Optionally, the first energy storage unit is a lithium titanate battery.

[0017] This invention also provides an energy storage control device applied to an energy storage system, the energy storage system comprising: a first energy storage unit and a second energy storage unit, both the first energy storage unit and the second energy storage unit being connected to a load, the second energy storage unit being a lithium-ion battery, and the energy storage control device comprising:

[0018] The detection module is used to detect the load current in real time.

[0019] The control module is used to determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit based on the load current, the upper limit of the output current of the second energy storage unit and the load current change rate, so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time.

[0020] Optionally, the control module includes:

[0021] The first control unit is configured to determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit if the load current is less than or equal to the upper limit of the output current of the second energy storage unit, based on the load current change rate and a preset change rate.

[0022] This invention also provides an energy storage system, including: a first energy storage unit and a second energy storage unit, wherein the first energy storage unit is connected to a load through a first converter unit, and the second energy storage unit is connected to the load through a second converter unit, and the first converter unit and the second converter unit are communicatively connected;

[0023] The first converter unit or the second converter unit includes the energy storage control device described in the embodiments of the present invention.

[0024] This invention also provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in this invention.

[0025] This invention also provides a non-volatile computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method described in this invention.

[0026] By applying the technical solution of this invention, a first energy storage unit and a second energy storage unit (ordinary lithium-ion battery) are combined. The second energy storage unit has a constant output power according to demand, while the first energy storage unit varies its output power to respond to changes in load power in real time. This not only achieves real-time response to changes in load power but also ensures the economy of energy storage. By using two energy storage units to supply power, the problem of frequent charging and discharging or high-rate charging and discharging of lithium-ion batteries affecting their service life is avoided, thereby improving the overall operating life of the energy storage system. Attached Figure Description

[0027] Figure 1 This is a flowchart of the energy storage control method provided in the embodiments of the present invention;

[0028] Figure 2 This is a structural block diagram of the energy storage control device provided in the embodiments of the present invention;

[0029] Figure 3 This is a schematic diagram of the energy storage system provided in an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0031] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0033] The energy storage system involved in this invention includes a first energy storage unit and a second energy storage unit, both of which are connected to a load. This invention also provides an energy storage control method based on the aforementioned energy storage system.

[0034] Figure 1 This is a flowchart of the energy storage control method provided in the embodiments of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0035] S101, real-time monitoring of load current.

[0036] S102, based on the load current, the upper limit of the output current of the second energy storage unit and the load current change rate, determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time.

[0037] The upper limit of the output current of the second energy storage unit can be its rated output current. The first energy storage unit can be a lithium titanate battery, and the second energy storage unit can be a regular lithium-ion battery. Lithium titanate batteries can achieve a high charge-discharge rate of 6C and a cycle life of over 25,000 cycles, meeting the needs of applications with large load power variations. However, they are more expensive. Combining lithium titanate batteries with regular lithium-ion batteries creates an energy storage system that offers both economic efficiency and high rate performance, better promoting the multi-scenario application of energy storage systems. For the same capacity, using only lithium titanate batteries results in a high price; adding regular lithium-ion batteries reduces energy storage costs without affecting output power.

[0038] This embodiment combines a first energy storage unit and a second energy storage unit (ordinary lithium-ion battery). The second energy storage unit outputs a constant power according to demand, while the first energy storage unit varies its output power to respond to changes in load power in real time. This not only enables real-time response to changes in load power but also achieves energy storage economy. By using two energy storage units to supply power, the problem of frequent charging and discharging or high-rate charging and discharging of lithium-ion batteries affecting their service life is avoided, thus improving the overall operating life of the energy storage system.

[0039] Specifically, based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, the energy storage unit that supplies power to the load is determined, and the output current of that energy storage unit is controlled, including:

[0040] If the load current is less than or equal to the upper limit of the output current of the second energy storage unit, then the energy storage unit that supplies power to the load is determined and the output current of the energy storage unit is controlled according to the load current change rate and the preset change rate.

[0041] If the load current is greater than the upper limit of the output current of the second energy storage unit, then it is determined that the first energy storage unit and the second energy storage unit will jointly supply power to the load, the output current of the second energy storage unit will be kept constant at the upper limit of the output current, and the output current of the first energy storage unit will be controlled to be the load current minus the upper limit of the output current.

[0042] The preset rate of change can be the rate of current change that the second energy storage unit can withstand.

[0043] In other words, when the load current is less than or equal to the upper limit of the output current of the second energy storage unit, the specific energy storage unit supplying power to the load is determined based on the load current change rate and a preset change rate. This allows for reasonable control of the energy storage system's output, achieving effective utilization of both the first and second energy storage units. It avoids the problem of frequent charging and discharging or high-rate charging and discharging of lithium-ion batteries affecting their lifespan, thus improving the overall operational lifespan of the energy storage system. When the load current exceeds the upper limit of the output current of the second energy storage unit, the second energy storage unit maintains a constant maximum output power, while the first energy storage unit adjusts its output power in real time according to changes in the load current to respond to load power changes in real time.

[0044] Furthermore, based on the load current change rate and a preset change rate, the energy storage unit supplying power to the load is determined, and the output current of the energy storage unit is controlled, including:

[0045] Detect the rate of change of load current within a preset time period;

[0046] If the load current change rate is less than the preset change rate, then the second energy storage unit will supply power to the load, and the output current of the second energy storage unit will be controlled to be constant at the load current, so that the power output and power change of the second energy storage unit are limited.

[0047] If the load current change rate is greater than or equal to a preset change rate, then the first energy storage unit and the second energy storage unit jointly supply power to the load. The output current of the second energy storage unit is controlled to be constant at a first current, and the output current of the first energy storage unit is controlled to be the load current minus the first current, wherein the first current is less than or equal to the upper limit of the output current of the second energy storage unit. That is, the second energy storage unit limits the power output and the amount of power change, and the first energy storage unit adjusts its own output power in real time according to the change of load current so that the first energy storage unit responds to the change of load power in real time.

[0048] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0049] Based on the same inventive concept, embodiments of the present invention also provide an energy storage control device, which can be used to implement the energy storage control method described in the above embodiments. This energy storage control device can be implemented through software and / or hardware. The energy storage control device is applied to an energy storage system, which includes: a first energy storage unit and a second energy storage unit, both of which are connected to a load, and the second energy storage unit is a lithium-ion battery.

[0050] Figure 2 This is a structural block diagram of the energy storage control device provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the energy storage control device includes:

[0051] Detection module 21 is used to detect load current in real time;

[0052] Control module 22 is used to determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit based on the load current, the upper limit of the output current of the second energy storage unit and the load current change rate, so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time.

[0053] Optionally, the control module 22 includes: a first control unit, configured to determine the energy storage unit supplying power to the load and control the output current of the energy storage unit based on the load current change rate and a preset change rate if the load current is less than or equal to the upper limit of the output current of the second energy storage unit.

[0054] Optionally, the first control unit is specifically used for:

[0055] Detect the rate of change of load current within a preset time period;

[0056] If the load current change rate is less than the preset change rate, then it is determined that the second energy storage unit will supply power to the load, and the output current of the second energy storage unit will be controlled to be constant at the load current;

[0057] If the load current change rate is greater than or equal to the preset change rate, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the first current, and the output current of the first energy storage unit is controlled to be the load current minus the first current, wherein the first current is less than or equal to the upper limit value of the output current of the second energy storage unit.

[0058] Optionally, the control module 22 includes: a second control unit, configured to determine that the first energy storage unit and the second energy storage unit jointly supply power to the load if the load current is greater than the upper limit of the output current of the second energy storage unit, control the output current of the second energy storage unit to be constant at the upper limit of the output current, and control the output current of the first energy storage unit to be the load current minus the upper limit of the output current.

[0059] Optionally, the first energy storage unit is a lithium titanate battery.

[0060] The above-described energy storage control device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the energy storage control method provided in the embodiments of the present invention.

[0061] This invention also provides an energy storage system, including: a first energy storage unit and a second energy storage unit, wherein the first energy storage unit is connected to a load via a first converter unit, and the second energy storage unit is connected to the load via a second converter unit, and the first converter unit and the second converter unit are communicatively connected; the first converter unit or the second converter unit includes the energy storage control device described in the above embodiments.

[0062] The energy storage system and energy storage control method described below are illustrated with a specific embodiment. However, it is worth noting that this specific embodiment is only for better illustration of this application and does not constitute an undue limitation of this application. Explanations of terms that are the same or corresponding to those in the above embodiments will not be repeated in this embodiment.

[0063] like Figure 3As shown, the energy storage system 10 includes: a lithium titanate battery pack 11 (i.e., the first energy storage unit mentioned above), a conventional lithium-ion battery pack 12 (i.e., the second energy storage unit mentioned above), a first converter unit 13, a second converter unit 14, and a battery management system (BMS) 15. The lithium titanate battery pack 11 is connected to a DC load 20 through the first converter unit 13, and the conventional lithium-ion battery pack 12 is connected to the DC load 20 through the second converter unit 14. The first converter unit 13, the second converter unit 14, and the battery management system 15 exchange data via a CAN bus to achieve communication. The energy storage system outputs a DC voltage (e.g., 400V). The energy storage system 10 and the DC load 20 are connected to the power grid 30 through a third converter unit 31.

[0064] The battery management system 15 is used to detect the state of the lithium titanate battery pack 11 and the ordinary lithium-ion battery pack 12 and to estimate the state of charge (SOC). The battery management system 15 can set a current change rate threshold k, i.e., the aforementioned preset change rate, which can be the current change rate that the ordinary lithium-ion battery pack 12 can withstand. The battery management system 15 also sets an upper limit I for the output current of the ordinary lithium-ion battery pack 12. L Specifically, it can be the rated output current of a regular lithium-ion battery pack 12.

[0065] Energy storage control methods include the following steps:

[0066] Initially, the second converter unit 14 is in standby mode with zero output power, and the first converter unit 13 continuously monitors the DC load side current I. o .

[0067] (1) When 0≤I o ≤I L At that time, the first converter unit 13 detects the rate of change of current di / dt within time t.

[0068] When di / dt < k, the first converter unit 13 sends a power generation command to the second converter unit 14 via CAN communication and sets the constant discharge current value to I. o This limits the power output and power variation of ordinary lithium-ion battery packs.

[0069] When di / dt≥k, the first converter unit 13 sends a power generation command to the second converter unit 14 via CAN communication and sets a constant discharge current value of I (I≤I). L Meanwhile, the first converter unit 13 according to I o The output power is adjusted in real time according to the changes, that is, the output current of the first converter unit 13 is I1=I o -I limits the power output and power change of the ordinary lithium-ion battery pack 12, and the lithium titanate battery pack 11 responds to the power change in real time.

[0070] (2) When I o >I L At that time, the first converter unit 13 sends a power generation command to the second converter unit 14 via CAN communication and sets the constant discharge current value to I. L Meanwhile, the first converter unit 13 according to I o The output power is adjusted in real time according to the changes, that is, the output current of the first converter unit 13 is I1=I o -I L .

[0071] The overall energy storage system ensures that the power output of the ordinary lithium-ion battery pack 12 is limited, while the lithium titanate battery pack 11 responds to load power changes in real time. The above-mentioned energy storage control can also be executed by the second converter unit 14. In this case, the first converter unit 13 receives the power generation command from the second converter unit 14 and operates according to the power generation command. The specific details will not be elaborated further.

[0072] Considering that lithium titanate batteries can achieve a high charge-discharge rate of 6C and a cycle life of over 25,000 cycles, meeting the needs of applications with large load power variations, but are relatively expensive, while ordinary lithium-ion batteries have a price advantage, but their charge-discharge rate and cycle life are relatively lacking, the energy internet DC energy storage system and its energy storage control method in this embodiment combine lithium titanate batteries with ordinary lithium-ion batteries. The lithium titanate battery detects the load current state and changes its output power to respond to load power changes in real time, while the ordinary lithium-ion battery maintains a constant output power according to demand. This not only achieves real-time response to load power changes but also ensures the economy of energy storage, improves the overall operating life of the energy storage system, and forms an energy storage system with both economic efficiency and high rate performance, which can better promote the multi-scenario application of energy storage systems.

[0073] This invention also provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described in the above embodiments.

[0074] This invention also provides a non-volatile computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method described in the above embodiments.

[0075] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0076] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An energy storage control method, characterized in that, The energy storage system includes: a first energy storage unit and a second energy storage unit, both of which are connected to a load. The second energy storage unit is a lithium-ion battery. The energy storage control method includes: Real-time load current detection; Based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, the energy storage unit that supplies power to the load is determined and the output current of the energy storage unit is controlled so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time. Based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, the energy storage unit that supplies power to the load is determined, and the output current of the energy storage unit is controlled, including: If the load current is less than or equal to the upper limit of the output current of the second energy storage unit, then based on the load current change rate and the preset change rate, the energy storage unit that supplies power to the load is determined and the output current of the energy storage unit is controlled, wherein the preset change rate is the current change rate that the second energy storage unit can withstand. Based on the load current change rate and a preset change rate, determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit, including: Detect the rate of change of load current within a preset time period; If the load current change rate is less than the preset change rate, then it is determined that the second energy storage unit will supply power to the load, and the output current of the second energy storage unit will be controlled to be constant at the load current; If the load current change rate is greater than or equal to the preset change rate, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the first current, and the output current of the first energy storage unit is controlled to be the load current minus the first current, wherein the first current is less than or equal to the upper limit value of the output current of the second energy storage unit.

2. The method according to claim 1, characterized in that, Based on the load current, the upper limit of the output current of the second energy storage unit, and the load current change rate, the energy storage unit that supplies power to the load is determined, and the output current of the energy storage unit is controlled, including: If the load current is greater than the upper limit of the output current of the second energy storage unit, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the upper limit of the output current, and the output current of the first energy storage unit is controlled to be the load current minus the upper limit of the output current.

3. The method according to any one of claims 1 to 2, characterized in that, The first energy storage unit is a lithium titanate battery.

4. An energy storage control device, applied to an energy storage system, characterized in that, The energy storage system includes: a first energy storage unit and a second energy storage unit, both of which are connected to a load. The second energy storage unit is a lithium-ion battery. The energy storage control device includes: The detection module is used to detect the load current in real time. The control module is used to determine the energy storage unit that supplies power to the load and control the output current of the energy storage unit based on the load current, the upper limit of the output current of the second energy storage unit and the load current change rate, so that the second energy storage unit limits the power output and the first energy storage unit responds to the load power change in real time. The control module includes: a first control unit, configured to determine the energy storage unit supplying power to the load and control the output current of the energy storage unit based on the load current change rate and a preset change rate if the load current is less than or equal to the upper limit of the output current of the second energy storage unit, wherein the preset change rate is the current change rate that the second energy storage unit can withstand. The first control unit is specifically used for: Detect the rate of change of load current within a preset time period; If the load current change rate is less than the preset change rate, then it is determined that the second energy storage unit will supply power to the load, and the output current of the second energy storage unit will be controlled to be constant at the load current; If the load current change rate is greater than or equal to the preset change rate, then it is determined that the first energy storage unit and the second energy storage unit jointly supply power to the load, the output current of the second energy storage unit is controlled to be constant at the first current, and the output current of the first energy storage unit is controlled to be the load current minus the first current, wherein the first current is less than or equal to the upper limit value of the output current of the second energy storage unit.

5. An energy storage system, characterized in that, include: A first energy storage unit and a second energy storage unit, wherein the first energy storage unit is connected to the load through a first converter unit, and the second energy storage unit is connected to the load through a second converter unit, and the first converter unit and the second converter unit are communicatively connected; The first converter unit or the second converter unit includes the energy storage control device as described in claim 4.

6. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor, when executing the computer program, implements the steps of the method according to any one of claims 1 to 3.

7. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

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