Flywheel energy storage system and rotating variable inertia control method and device thereof

Abstract

The application discloses a flywheel energy storage system and a rotating variable inertia control method and device thereof, wherein the method can realize that when a short fluctuation occurs in a power grid frequency, the speed of a flywheel motor is basically not changed, the kinetic energy is changed by changing the rotating inertia of a flywheel motor rotor, then the conversion between mechanical energy and electric energy is realized by the change of the electromagnetic torque of the motor electromechanically coupled with the flywheel motor, the bidirectional and orderly flow between the kinetic energy of the flywheel motor rotor and the power grid electric energy is realized, the converter link between the motor and the power grid is cancelled, and the excellent overload capacity of the motor itself is fully exerted to cope with the short fluctuation caused by the voltage of the power grid due to the switching of a load and other factors, and the high-quality power supply and safety and stability of the power system are ensured.

Description

Technical Field

[0001] This invention relates to the field of flywheel technology with variable moment of inertia, and specifically to a flywheel energy storage system and its variable moment of inertia control method and device. Background Technology

[0002] The development of flywheel energy storage technology aims to improve energy density, power density, efficiency, and reduce costs. The industrialization of flywheel energy storage technology involves developing demonstrations, promotion, and large-scale applications in specific fields, with large-scale production being a key factor in reducing operating costs. High-speed and variable-speed motor-controlled bidirectional converters are a major component of the system's higher costs and are crucial for cost reduction. To further reduce system costs while achieving bidirectional, orderly flow of kinetic energy between the flywheel motor rotor system and grid power, the converter stage between the motor and the grid has been eliminated. However, due to grid voltage instability, this can easily cause short-term fluctuations in grid frequency, compromising the high-quality power supply and security of the power system. Summary of the Invention

[0003] Therefore, the technical problem to be solved by this invention is to overcome the shortcomings of existing technologies where unstable grid voltage easily causes short-term fluctuations in grid frequency, making it impossible to guarantee high-quality power supply and security of the power system. This invention provides a flywheel energy storage system and its rotational variable inertia control method and device.

[0004] According to a first aspect, the present invention provides a method for controlling the rotational variable inertia of a flywheel energy storage system, comprising the following steps:

[0005] In response to turbine startup, the flywheel motor speed is monitored in real time;

[0006] If the flywheel motor speed increases to the preset speed, the current voltage and frequency of the power grid will be monitored in real time.

[0007] If the current voltage of the power grid is greater than a preset threshold, increase the rotational inertia of the flywheel and control the power grid to supply power to the flywheel motor until the current frequency of the power grid returns to the normal value;

[0008] If the current voltage of the power grid is less than or equal to a preset threshold, reduce the rotational inertia of the flywheel and control the flywheel motor to supply power to the power grid until the current frequency of the power grid returns to normal.

[0009] Optionally, the rotational variable inertia control method of the flywheel energy storage system further includes:

[0010] Obtain the current energy storage capacity of the flywheel energy storage system;

[0011] If the current energy storage capacity is less than or equal to the preset capacity, reduce the flywheel rotational inertia and execute the flywheel power generation mode;

[0012] If the current energy storage capacity is greater than the preset capacity, increase the flywheel rotational inertia to execute the flywheel charging mode.

[0013] Optionally, the method for controlling the rotational inertia of the flywheel energy storage system further includes: real-time monitoring of the flywheel's rotational inertia and operating status, and sending the flywheel's rotational inertia and operating status to a remote terminal.

[0014] Optionally, the flywheel moment of inertia can be increased or decreased by using a variable moment of inertia flywheel structure.

[0015] According to a second aspect, the present invention also provides a rotational variable inertia control device for a flywheel energy storage system, comprising the following modules:

[0016] The flywheel speed monitoring module is used to monitor the flywheel motor speed in real time in response to turbine startup;

[0017] The power grid monitoring module is used to monitor the current voltage and frequency of the power grid in real time when the flywheel motor speed increases to a preset speed.

[0018] The rotational inertia increase module is used to increase the rotational inertia of the flywheel and control the power grid to supply power to the flywheel motor when the current voltage of the power grid is greater than a preset threshold until the current frequency of the power grid returns to the normal value.

[0019] The moment of inertia reduction module is used to reduce the moment of inertia of the flywheel and control the flywheel motor to supply power to the grid until the current frequency of the grid returns to normal if the current voltage of the grid is less than or equal to a preset threshold.

[0020] Optionally, the rotational inertia control device of the flywheel energy storage system further includes:

[0021] An energy storage capacity acquisition module is used to acquire the current energy storage capacity of the flywheel energy storage system;

[0022] The flywheel power generation control module is used to reduce the flywheel rotational inertia and execute the flywheel power generation mode if the current energy storage capacity is less than or equal to the preset capacity;

[0023] The flywheel charging control module is used to increase the flywheel rotational inertia to execute the flywheel charging mode if the current energy storage capacity is greater than the preset capacity.

[0024] Optionally, the rotational inertia control device of the flywheel energy storage system further includes: a transmitting module, used to monitor the rotational inertia and operating status of the flywheel in real time, and to transmit the rotational inertia and operating status of the flywheel to a remote terminal.

[0025] According to a third aspect, the present invention also provides a flywheel energy storage system, for use in a method for controlling the rotational inertia of the flywheel energy storage system described in the first aspect or any embodiment of the first aspect, comprising:

[0026] Compressed air equipment;

[0027] A turbine is connected to the compressed air equipment;

[0028] A variable moment of inertia flywheel structure is connected to the turbine;

[0029] A flywheel motor is connected to the flywheel structure with variable moment of inertia;

[0030] The power grid is connected to the flywheel motor via a controllable switch;

[0031] The controller is connected to the turbine, the variable moment of inertia flywheel structure, the power grid, and the flywheel motor.

[0032] According to a fourth aspect, embodiments of the present invention also provide a computer-readable storage medium storing computer instructions for controlling the rotational inertia of a flywheel energy storage system according to the first aspect or any embodiment of the first aspect.

[0033] According to a fifth aspect, embodiments of the present invention also provide a computer device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the rotational variable inertia control method of the flywheel energy storage system according to the first aspect or any embodiment of the first aspect.

[0034] The technical solution of this invention has the following advantages:

[0035] The rotational inertia control method for flywheel energy storage systems provided by this invention does not require changing the speed of the flywheel motor when the grid frequency experiences short-term fluctuations. Instead, it changes the kinetic energy by altering the rotational inertia of the flywheel motor rotor. Then, it converts mechanical energy into electrical energy through changes in the electromagnetic torque of the flywheel motor via electromechanical coupling. This achieves bidirectional and orderly flow between the kinetic energy of the flywheel motor rotor and the electrical energy of the grid, eliminating the converter stage between the motor and the grid. Furthermore, it fully utilizes the motor's excellent overload capacity to cope with short-term fluctuations in grid voltage caused by factors such as load switching, ensuring high-quality power supply and safe and stable power system operation. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 A flowchart illustrating a specific example of the rotational variable inertia control method for a flywheel energy storage system in this invention;

[0038] Figure 2 This is a three-dimensional structural diagram of the variable moment of inertia flywheel structure provided in this invention.

[0039] Figure 3 This is a schematic diagram of the flywheel energy storage system provided in this invention;

[0040] Figure 4 This is a structural block diagram of the rotational variable inertia control device of the wheel energy storage system in this invention;

[0041] Figure 5 This is a schematic diagram of the hardware structure of the computer device in this invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Outer retaining ring rotor; 2. Inner support ring rotor; 3. Connecting rod;

[0044] 4. Variable inertia components; 51-Compressed air equipment; 52-Turbine;

[0045] 53-Variable moment of inertia flywheel structure; 54-Flywheel motor;

[0046] 55-Power grid; 56-Controller; 57-Controllable switch. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] This embodiment provides a method for controlling the rotational variable inertia of a flywheel energy storage system, applied to flywheel energy storage systems, such as... Figure 1 As shown, it includes the following steps:

[0052] Step S11: In response to turbine startup, monitor the flywheel motor speed in real time.

[0053] The turbine is started and operated by a compressed air device, and the flywheel motor speed is monitored in real time by a controller.

[0054] Step S12: When the flywheel motor speed increases to the preset speed, monitor the current voltage and frequency of the power grid in real time.

[0055] For example, if the preset speed is 3000 rpm, when the flywheel motor speed increases to 3000 rpm, the flywheel motor and the power grid frequency 50H are basically in sync. During the execution of step S12, the flywheel motor operates electrically to overcome the rotor's no-load running loss and to operate in standby mode.

[0056] Step S13: If the current voltage of the power grid is greater than the preset threshold, increase the rotational inertia of the flywheel and control the power grid to supply power to the flywheel motor until the current frequency of the power grid returns to the normal value.

[0057] For example, if the current frequency of the power grid is detected to be outside the normal range, the current voltage of the power grid will fluctuate and exceed a preset threshold. This preset threshold is used as a reference voltage. If the current voltage of the power grid is greater than the preset threshold, it means that the current voltage of the power grid fluctuates greatly. The energy storage mode is triggered by threshold control, the flywheel is started to increase inertia, the motor's electric torque increases, and electrical energy is input until the current frequency of the power grid returns to the normal value.

[0058] Step S14: If the current grid voltage is less than or equal to a preset threshold, reduce the flywheel's rotational inertia and control the flywheel motor to supply power to the grid until the grid's current frequency returns to normal.

[0059] For example, if the current frequency of the power grid is detected to be outside the normal range, the current voltage of the power grid will fluctuate. If the current voltage fluctuation is small, the energy release mode will be triggered by threshold control, the flywheel will start to run with reduced inertia, the motor's generating resistance torque will increase, and the output will feed back electrical energy to the power grid.

[0060] In an optional implementation, the rotational inertia control method of the flywheel energy storage system in this embodiment further includes:

[0061] Obtain the current energy storage capacity of the flywheel energy storage system;

[0062] If the current energy storage capacity is less than or equal to the preset capacity, reduce the flywheel rotational inertia and execute the flywheel power generation mode;

[0063] If the current energy storage capacity is greater than the preset capacity, increase the flywheel rotational inertia to execute the flywheel charging mode.

[0064] Based on the current energy storage capacity of the flywheel energy storage system, the flywheel's rotational inertia can be flexibly controlled, thereby meeting user needs.

[0065] In another optional implementation, the rotational inertia control method of the flywheel energy storage system in this embodiment further includes: real-time monitoring of the flywheel rotational inertia and flywheel operating status, and sending the flywheel rotational inertia and flywheel operating status to a remote terminal.

[0066] The flywheel moment of inertia and flywheel operating status are sent to a remote terminal, so that users of the remote terminal can obtain information about the flywheel moment of inertia and flywheel operating status in real time.

[0067] In another alternative implementation, the variable inertia control method of the flywheel energy storage system in this embodiment increases or decreases the flywheel's rotational inertia through a variable inertia flywheel structure.

[0068] Flywheel moment of inertia analysis, for example: the kinetic energy of the rotor of a flywheel motor with a moment of inertia of J and a motor speed of ω is: The change of kinetic energy over time produces the ability to do work:

[0069]

[0070] Power balance equation for a constant-speed flywheel motor energy storage system:

[0071] Motor electromagnetic torque:

[0072] When the variable moment of inertia flywheel structure moves outward, it increases the moment of inertia, resulting in a positive electromagnetic torque and the flywheel motor operating in electric mode. When the variable moment of inertia flywheel structure moves inward, it decreases the moment of inertia, resulting in a negative electromagnetic torque and the flywheel motor operating in generator mode.

[0073] The rotational inertia control method of the flywheel energy storage system in this embodiment of the invention does not require changing the speed of the flywheel motor when the grid frequency fluctuates briefly. Instead, it changes the kinetic energy by changing the rotational inertia of the flywheel motor rotor. Then, it achieves the conversion of mechanical energy into electrical energy through the change of the electromagnetic torque of the flywheel motor electromechanical coupling, realizing the bidirectional orderly flow between the kinetic energy of the flywheel motor rotor and the electrical energy of the grid. This eliminates the converter link between the motor and the grid, and fully utilizes the excellent overload capacity of the motor itself to cope with short-term fluctuations in grid voltage caused by factors such as load switching, ensuring high-quality power supply and safe and stable power system operation.

[0074] This embodiment provides a flywheel energy storage system for the rotational variable inertia control method of the flywheel energy storage system in the above embodiments, such as... Figure 2 As shown, it includes: a compressed air device 51, a turbine 52, a variable moment of inertia flywheel structure 53, a flywheel motor 54, an electrical grid 55, and a controller 56. The turbine 52 is connected to the compressed air device 51, and the variable moment of inertia flywheel structure 53 is connected to the turbine 52; the flywheel motor 54 is connected to the variable moment of inertia flywheel structure 53; the electrical grid 55 is connected to the flywheel motor 54 via a controllable switch 57; and the controller 56 is connected to the turbine 52, the variable moment of inertia flywheel structure 53, the electrical grid 55, and the flywheel motor 54.

[0075] Among them, the variable moment of inertia flywheel structure mentioned above, such as Figure 3As shown, it includes: a variable inertia rotor and a stator; the variable inertia rotor includes: an outer retaining ring rotor 1, which has a circular ring structure; an inner support ring rotor 2, which also has a circular ring structure; connecting rods 3, which are disposed between the outer retaining ring rotor 1 and the inner support ring rotor 2, and the two ends of the connecting rods 3 are fixedly connected to the outer retaining ring rotor 1 and the inner support ring rotor 2 respectively; there are 12 connecting rods 3, and each connecting rod 3 is provided with a variable inertia component 4; in this embodiment, the variable inertia component 4 is slidably disposed on the connecting rod 3 and is driven to move along the length direction of the connecting rod 3 to change the rotational inertia of the flywheel; the variable inertia component 4 is a fan-shaped structure adapted to the shape of the outer retaining ring rotor 1 and the inner support ring rotor 2 respectively. The above-mentioned variable inertia components 4 are axially symmetrically distributed about the axis of the variable inertia rotor, thereby ensuring the rotational stability of the variable inertia flywheel structure during rotation. The rotor drive disk is located at the ends of the outer retaining ring rotor 1, the variable inertia component 4, and the inner support ring rotor 2, and is used to drive the three of them to rotate synchronously. The rotor drive disk is coaxially connected to the motor for rotational transmission.

[0076] The flywheel energy storage system in this embodiment, through the rotational inertia control method of the flywheel energy storage system in the above embodiment, does not need to change the speed of the flywheel motor when the grid frequency fluctuates briefly. Instead, it changes the kinetic energy by changing the rotational inertia of the flywheel motor rotor. Then, it realizes the conversion of mechanical energy into electrical energy through the change of the electromagnetic torque of the flywheel motor electromechanical coupling, achieving bidirectional orderly flow between the kinetic energy of the flywheel motor rotor system and the electrical energy of the grid. This eliminates the converter link between the motor and the grid, and fully utilizes the excellent overload capacity of the motor itself to cope with short-term fluctuations in grid voltage caused by factors such as load switching, ensuring high-quality power supply and safe and stable power system.

[0077] This embodiment also provides a rotational variable inertia control device for a flywheel energy storage system, such as... Figure 4 As shown, it includes the following modules:

[0078] Flywheel speed monitoring module 41 is used to monitor the flywheel motor speed in real time in response to turbine start-up;

[0079] The power grid monitoring module 42 is used to monitor the current voltage and frequency of the power grid in real time when the flywheel motor speed increases to a preset speed.

[0080] The rotational inertia increasing module 43 is used to increase the rotational inertia of the flywheel and control the power grid to supply power to the flywheel motor when the current voltage of the power grid is greater than a preset threshold until the current frequency of the power grid returns to the normal value.

[0081] The moment of inertia reduction module 44 is used to reduce the moment of inertia of the flywheel and control the flywheel motor to supply power to the grid until the current grid frequency returns to the normal value if the current grid voltage is less than or equal to a preset threshold.

[0082] The rotational inertia control device for the flywheel energy storage system in this embodiment further includes:

[0083] The energy storage capacity acquisition module is used to acquire the current energy storage capacity of the flywheel energy storage system;

[0084] The flywheel power generation control module is used to reduce the flywheel's rotational inertia and execute the flywheel power generation mode if the current energy storage capacity is less than or equal to the preset capacity.

[0085] The flywheel charging control module is used to increase the flywheel's rotational inertia and execute the flywheel charging mode if the current energy storage capacity is greater than the preset capacity.

[0086] The variable inertia control device for the flywheel energy storage system in this embodiment further includes: a transmitting module, used to monitor the flywheel's rotational inertia and operating status in real time, and to transmit the flywheel's rotational inertia and operating status to a remote terminal.

[0087] Based on the same concept, embodiments of the present invention also provide a computer device, such as... Figure 5 As shown, the computer device may include a processor 61 and a memory 62, wherein the processor 61 and the memory 62 may be connected via a bus or other means. Figure 5 Taking the example of a connection between China and Israel via a bus.

[0088] Processor 61 can be a central processing unit (CPU). Processor 61 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0089] The memory 62, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules. The processor 61 executes various functional applications and data processing by running the non-transitory software programs, instructions, and modules stored in the memory 62, thereby realizing the rotational variable inertia control method of the flywheel energy storage system in the above embodiments.

[0090] The memory 62 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor 61, etc. Furthermore, the memory 62 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 62 may optionally include memory remotely located relative to the processor 61, and these remote memories may be connected to the processor 61 via a network. Examples of such networks include, but are not limited to, power grids, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0091] The one or more modules are stored in the memory 62. When executed by the processor 61, they execute the rotational variable inertia control method of the flywheel energy storage system in the embodiment shown in the figure.

[0092] The specific details of the above-mentioned computer equipment can be understood by referring to the relevant descriptions and effects in the embodiments shown in the accompanying drawings, and will not be repeated here.

[0093] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0094] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for controlling the rotational variable inertia of a flywheel energy storage system, characterized in that, Includes the following steps: In response to turbine startup, the flywheel motor speed is monitored in real time; If the flywheel motor speed increases to the preset speed, the current voltage and frequency of the power grid will be monitored in real time. If the current voltage of the power grid is greater than a preset threshold, the rotational inertia of the flywheel is increased through a variable moment of inertia flywheel structure, and the power grid is controlled to supply power to the flywheel motor until the current frequency of the power grid returns to the normal value; If the current voltage of the power grid is less than or equal to a preset threshold, the flywheel moment of inertia is reduced by the variable moment of inertia flywheel structure and the flywheel motor is controlled to supply power to the power grid until the current frequency of the power grid returns to the normal value. The method further includes: Obtain the current energy storage capacity of the flywheel energy storage system; If the current energy storage capacity is less than or equal to the preset capacity, reduce the flywheel rotational inertia and execute the flywheel power generation mode; If the current energy storage capacity is greater than the preset capacity, increase the flywheel rotational inertia to execute the flywheel charging mode; The flywheel moment of inertia and flywheel operating status are monitored in real time, and the flywheel moment of inertia and flywheel operating status are sent to a remote terminal.

2. A rotational variable inertia control device for a flywheel energy storage system, characterized in that, Includes the following modules: The flywheel speed monitoring module is used to monitor the flywheel motor speed in real time in response to turbine startup; The power grid monitoring module is used to monitor the current voltage and frequency of the power grid in real time when the flywheel motor speed increases to a preset speed. The rotational inertia increase module is used to increase the rotational inertia of the flywheel through a variable rotational inertia flywheel structure when the current voltage of the power grid is greater than a preset threshold, and to control the power grid to supply power to the flywheel motor until the current frequency of the power grid returns to the normal value. The rotational inertia reduction module is used to reduce the rotational inertia of the flywheel through a variable rotational inertia flywheel structure if the current voltage of the power grid is less than or equal to a preset threshold, and to control the flywheel motor to supply power to the power grid until the current frequency of the power grid returns to the normal value. The device further includes: An energy storage capacity acquisition module is used to acquire the current energy storage capacity of the flywheel energy storage system; The flywheel power generation control module is used to reduce the flywheel rotational inertia and execute the flywheel power generation mode if the current energy storage capacity is less than or equal to the preset capacity; The flywheel charging control module is used to increase the flywheel rotational inertia and execute the flywheel charging mode if the current energy storage capacity is greater than the preset capacity. The transmitting module is used to monitor the flywheel's rotational inertia and operating status in real time, and to transmit the flywheel's rotational inertia and operating status to a remote terminal.

3. A flywheel energy storage system, used in the rotational variable inertia control method of the flywheel energy storage system according to claim 1, characterized in that, include: Compressed air equipment; A turbine is connected to the compressed air equipment; A variable moment of inertia flywheel structure is connected to the turbine; A flywheel motor is connected to the variable moment of inertia flywheel structure; The power grid is connected to the flywheel motor via a controllable switch; The controller is connected to the turbine, the variable moment of inertia flywheel structure, the power grid, and the flywheel motor.

4. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the rotational variable inertia control method of the flywheel energy storage system of claim 1.

5. A computer device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes these computer instructions to perform the rotational variable inertia control method for the flywheel energy storage system as described in claim 1.

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