Brake control method and device for flywheel energy storage system

Abstract

The invention provides a brake control method and device for a flywheel energy storage system, and the method is applied to the flywheel energy storage system, and comprises the steps: S1, obtaining the monitoring data of a grid-side converter and a machine-side converter in response to a fault instruction; s2, according to the monitoring data, determining whether the machine-side converter has a fault or not; if yes, executing the step S3; if not, executing the step S4; s3, based on an alternating current side braking resistor, alternating current side free braking is carried out until a flywheel of the flywheel energy storage equipment is braked and stopped; s4, determining that the fault type is a flywheel body fault, and performing direct current side braking based on a direct current side braking resistor until flywheel braking is stopped; the direct-current side braking comprises direct-current side controlled braking and direct-current side free braking. By designing different braking modes and control methods thereof, when the flywheel energy storage system needs to be braked, control is matched, and the situation that the flywheel is out of control and is abraded or damaged due to the fact that energy stored in the flywheel cannot be released in time is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of flywheel energy storage, and in particular to a braking control method and device of a flywheel energy storage system. Background Art

[0002] See also Figure 1 , Figure 1 The figure is a schematic diagram of the composition of the existing magnetic levitation flywheel energy storage system. The current flywheel energy storage system is mainly composed of a transformer 4, a grid-side converter 5, a machine-side converter 6, a motor 7 and a flywheel energy storage device 8. After the electric energy is generated in the thermal power plant 1, it is stored in the flywheel energy storage system through the AC bus 3 for use by the mains power grid 2. Among them, the rotor of the motor 7 is connected to the flywheel of the flywheel energy storage device 8. When the host computer issues a charging instruction, the frequency converter drives the motor to accelerate according to the instruction, and drives the flywheel to accelerate at the same time, converting the electric energy into the kinetic energy of the flywheel; when the host computer issues a discharge instruction, the flywheel drives the motor to rotate in the system, and the frequency converter converts the kinetic energy of the flywheel into electric energy according to the instruction, and the flywheel slows down at the same time.

[0003] In the operation of the magnetic levitation flywheel energy storage system, there are generally three types of faults: grid-side converter fault, generator-side converter fault and flywheel fault. Once any of the three faults occurs and the flywheel needs to release the stored energy, it is necessary to use various methods to brake and release the energy, otherwise it will cause a serious accident.

[0004] The existing braking methods are all uncontrolled braking methods, that is, they are all achieved by using the back electromotive force of the motor. As the motor speed decreases, the back electromotive force becomes smaller, the braking will become slower and slower, and cannot respond quickly. Summary of the invention

[0005] The present invention provides a braking control method and device for a flywheel energy storage system. Two designed braking resistors are used to coordinate and control the flywheel energy storage system when braking is required, thereby improving the flexibility and controllability of braking.

[0006] In a first aspect, the present invention provides a braking control method for a flywheel energy storage system, which is applied to the flywheel energy storage system, wherein the flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, wherein a DC-side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC-side braking resistor is provided between the machine-side converter and the permanent magnet motor; the method comprises:

[0007] S1, in response to a fault instruction, obtaining monitoring data of the grid-side converter and the generator-side converter;

[0008] S2, determining whether the generator-side converter fails according to the monitoring data; if so, executing step S3; if not, executing step S4;

[0009] S3, performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops;

[0010] S4, determining that the fault type is a flywheel body fault, and performing DC side braking based on the DC side braking resistor until the flywheel stops; the DC side braking includes DC side controlled braking and DC side free braking.

[0011] Optionally, before step S2, the method further includes:

[0012] According to the monitoring data, it is determined whether the grid-side AC device fails.

[0013] Optionally, step S3 includes:

[0014] S31, disconnecting the circuit breaker between the machine-side converter and the AC-side braking resistor, and closing the circuit breaker between the AC-side braking resistor and the motor;

[0015] S32, consuming energy through the back electromotive force of the motor until the flywheel brakes to a stop.

[0016] Optionally, step S4 includes:

[0017] S41, disconnecting the switch between the grid-side converter and the generator-side converter, causing the generator-side converter to enter a voltage stabilization mode, and performing DC side braking according to the command type of the received braking command;

[0018] S42, when the command type is a controlled braking command, closing the switch of the DC side braking resistor, the machine-side converter enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor in the power mode until the flywheel brake stops;

[0019] S43, when the command type is a free braking command, the switch of the DC side braking resistor is closed, the machine-side converter remains in the voltage stabilization mode, and consumes power through the DC side braking resistor in the voltage stabilization mode until the flywheel brake stops.

[0020] In a second aspect, the present invention provides a brake control device for a flywheel energy storage system, which is applied to the flywheel energy storage system. The flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device. A DC-side brake resistor is provided between the grid-side converter and the machine-side converter, and an AC-side brake resistor is provided between the machine-side converter and the permanent magnet motor. The device comprises:

[0021] A response module, configured to obtain monitoring data of the grid-side converter and the generator-side converter in response to a fault instruction;

[0022] A first state determination module, used to determine whether the machine-side converter fails according to the monitoring data; if so, execute the AC side braking module; if not, execute the DC side braking module;

[0023] An AC side braking module, used for performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops;

[0024] The DC side braking module is used to determine that the fault type is a flywheel body fault, and perform DC side braking based on the DC side braking resistor until the flywheel brake stops; the DC side braking includes DC side controlled braking and DC side free braking.

[0025] Optionally, it also includes:

[0026] The second state determination module is used to determine whether the grid-side AC device fails based on the monitoring data.

[0027] Optionally, the AC side braking module includes:

[0028] A circuit breaker adjustment submodule, used to disconnect the circuit breaker between the machine-side converter and the AC-side braking resistor, and close the circuit breaker between the AC-side braking resistor and the motor;

[0029] The first energy consumption submodule is used to consume energy through the back electromotive force of the motor until the flywheel brakes to a stop.

[0030] Optionally, the DC side braking module includes:

[0031] A converter adjustment submodule, used for disconnecting the switch between the grid-side converter and the generator-side converter, so that the generator-side converter enters a voltage stabilization mode and performs DC side braking according to the command type of the received braking command;

[0032] A second consumption submodule is used for closing the switch of the DC side braking resistor when the command type is a controlled braking command, so that the machine-side converter enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor in the power mode until the flywheel brake stops;

[0033] The third consumption submodule is used to close the switch of the DC side braking resistor when the command type is a free braking command, so that the machine-side converter remains in the voltage stabilization mode and consumes power through the DC side braking resistor in the voltage stabilization mode until the flywheel brake stops.

[0034] In a third aspect, the present application provides an electronic device, comprising a processor and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the steps in the method provided in the first aspect are performed.

[0035] In a fourth aspect, the present application provides a storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps in the method provided in the first aspect are performed.

[0036] It can be seen from the above technical solutions that the present invention has the following advantages:

[0037] The present invention provides a braking control method and device for a flywheel energy storage system, which are applied to a flywheel energy storage system. The flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, wherein a DC side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC side braking resistor is provided between the machine-side converter and the permanent magnet motor; the method comprises: S1, in response to a fault instruction, obtaining monitoring data of the grid-side converter and the machine-side converter; S2, determining whether the machine-side converter fails according to the monitoring data; if so, executing step S3; if not, executing step S4; S3, performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops; S4, determining that the fault type is a flywheel body fault, and performing DC side braking based on the DC side braking resistor until the flywheel brake stops; the DC side braking includes DC side controlled braking and DC side free braking. By designing different braking modes and their control methods, when the flywheel energy storage system needs to brake, the control is coordinated to prevent the energy stored in the flywheel from not being released in time, causing the flywheel to lose control and cause wear or damage to the flywheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0039] Figure 1 It is a schematic diagram of the existing magnetic levitation flywheel energy storage system;

[0040] Figure 2 A flowchart of a first embodiment of a brake control method for a flywheel energy storage system according to the present invention;

[0041] Figure 3A flowchart of a second embodiment of a brake control method for a flywheel energy storage system according to the present invention;

[0042] Figure 4 A structural block diagram of a flywheel energy storage system according to a second embodiment of a brake control method for a flywheel energy storage system of the present invention;

[0043] Figure 5 The present invention is a structural block diagram of a brake control device embodiment of a flywheel energy storage system. DETAILED DESCRIPTION

[0044] The embodiment of the present invention provides a braking control method and device for a flywheel energy storage system. By designing two braking resistors, when the flywheel energy storage system needs to brake, the braking flexibility and controllability are improved.

[0045] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] For example, see Figure 2 , Figure 2 The present invention is a flow chart of a braking control method for a flywheel energy storage system in accordance with an embodiment of the present invention, which is applied to a flywheel energy storage system, wherein the flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, wherein a DC-side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC-side braking resistor is provided between the machine-side converter and the permanent magnet motor; the method comprises:

[0047] S1, in response to a fault instruction, obtaining monitoring data of the grid-side converter and the generator-side converter;

[0048] S2, determining whether the generator-side converter fails according to the monitoring data; if so, executing step S3; if not, executing step S4;

[0049] S3, performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops;

[0050] S4, determining that the fault type is a flywheel body fault, and performing DC side braking based on the DC side braking resistor until the flywheel stops; the DC side braking includes DC side controlled braking and DC side free braking.

[0051] A braking control method for a flywheel energy storage system provided in an embodiment of the present invention is applied to a flywheel energy storage system, wherein the flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, wherein a DC-side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC-side braking resistor is provided between the machine-side converter and the permanent magnet motor; the method comprises: S1, in response to a fault instruction, obtaining monitoring data of the grid-side converter and the machine-side converter; S2, determining whether the machine-side converter fails according to the monitoring data; if so, executing step S3; if not, executing step S4; S3, performing AC-side free braking based on the AC-side braking resistor until the flywheel brake of the flywheel energy storage device stops; S4, determining that the fault type is a flywheel body fault, and performing DC-side braking based on the DC-side braking resistor until the flywheel brake stops; the DC-side braking includes DC-side controlled braking and DC-side free braking. By designing different braking modes and their control methods, when the flywheel energy storage system needs to brake, the control is coordinated to prevent the energy stored in the flywheel from not being released in time, causing the flywheel to lose control and cause wear or damage to the flywheel.

[0052] For example 2, please refer to Figure 3 , Figure 3 This is a flow chart of a second embodiment of a brake control method for a flywheel energy storage system of the present invention, which is applied to Figure 4 In the flywheel energy storage system shown, the flywheel energy storage system includes: a flywheel inverter 10, a permanent magnet motor 7 and a flywheel 81, the flywheel inverter 10 includes: a grid-side circuit breaker 15, a grid-side reactor 14, a grid-side converter 5, a machine-side converter 6, a machine-side reactor 13 and a machine-side circuit breaker 12, a DC-side braking resistor 9 is provided between the grid-side converter 5 and the machine-side converter 6, and an AC-side braking resistor 11 is provided between the machine-side converter 6 and the permanent magnet motor 7; the method includes:

[0053] Step S201, in response to a fault instruction, obtaining monitoring data of the grid-side converter 5 and the generator-side converter 6;

[0054] Step S202, judging whether the grid-side AC device 5 fails according to the monitoring data;

[0055] Step S203, determining whether the generator-side converter 6 fails according to the monitoring data; if so, executing step S204; if not, executing step S206;

[0056] Step S204, disconnecting the machine-side circuit breaker 12 between the machine-side converter 6 and the AC-side braking resistor 11, and closing the circuit breaker between the AC-side braking resistor 11 and the motor 7;

[0057] Step S205, consuming energy through the back electromotive force of the motor 7 until the flywheel 81 brakes to a stop;

[0058] Step S206, disconnecting the switch between the grid-side converter 5 and the generator-side converter 6, so that the generator-side converter 6 enters a voltage stabilization mode and performs DC side braking according to the command type of the received braking command;

[0059] Step S207, when the command type is a controlled braking command, the switch of the DC side braking resistor 9 is closed, and the machine-side converter 6 enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor 9 in the power mode until the flywheel brake stops;

[0060] Step S208, when the command type is a free braking command, the switch of the DC side braking resistor 9 is closed, the machine-side converter 6 remains in the voltage stabilization mode, and consumes power through the DC side braking resistor 9 in the voltage stabilization mode until the flywheel 81 stops braking.

[0061] It should be noted that, under normal circumstances, the braking resistor will be disconnected by a switch, and when braking is required, different braking modes will be implemented by controlling the opening and closing of the circuit breaker, thereby releasing the energy of the flywheel 81.

[0062] In the control of the AC and DC braking resistors of the flywheel energy storage converter, there are three braking modes under different working conditions: controlled braking (i.e. power braking through the DC side braking resistor), DC side free braking (i.e. uncontrolled power braking through the DC side braking resistor) and AC side free braking (i.e. uncontrolled power braking through the AC side braking resistor).

[0063] Specifically, the working principle of the DC side braking mode is: when a certain link of the flywheel energy storage system fails (excluding uncontrollable braking conditions), the energy of the flywheel 81 needs to be released to stop it, and the switch between the grid-side converter 5 and the machine-side converter 6 will be disconnected, and the machine-side converter 6 will enter the voltage stabilization mode, stabilize the DC side voltage at a design value, and wait until the braking command is received. When a controlled braking command is received, the switch of the DC side braking resistor 9 is closed, and the flywheel energy storage system enters the power mode from the voltage stabilization mode. At this time, the energy will be consumed by the DC side braking resistor 9, and the controllable power braking mode is realized through the power closed-loop control, that is, controlled braking; when a free braking command is received, the switch of the DC side braking resistor 9 will be closed, and the braking voltage is a stabilization voltage value larger than the back electromotive force, and the energy will be consumed by the DC side braking resistor 9, that is, free braking on the DC side.

[0064] The working principle of the AC side braking mode is: when the machine-side converter 6 fails or the machine-side converter 6 is shut down and cannot be started, the machine-side circuit breaker 12 between the machine-side converter 6 and the AC side braking resistor 11 is directly disconnected, and the circuit breaker between the AC side braking resistor 11 and the motor 7 is closed, that is, a resistor is connected to the end of the motor 7, and energy is consumed through the back electromotive force of the motor 7. At this time, the braking mode is uncontrolled, that is, the AC side is freely braked. Under this braking mode, energy consumption will become slower and slower.

[0065] In the embodiment of the present invention, when the grid-side converter 5 fails, the energy of the flywheel 81 needs to be released. If the machine-side converter 6 is not faulty, the DC side controlled braking is preferentially selected. By mode switching, the machine-side converter 6 is switched from the voltage stabilization mode to the power mode. Through a closed-loop power control, a controllable power braking mode is implemented. The braking speed at this time is close to the discharge speed during normal operation, and the braking speed is the fastest. Free braking on the DC side can also be selected because the braking voltage at this time is larger than the back electromotive force, and the braking mode speed is faster.

[0066] When the machine-side converter 6 fails, no matter whether the grid-side converter 5 fails or not, the flywheel 81 can only select free braking on the AC side when braking is needed. Since the voltage during braking is the back electromotive force of the motor 7, as the speed of the motor 7 decreases, the back electromotive force decreases, and the braking speed becomes slower and slower.

[0067] When the grid-side converter 5 and the generator-side converter 6 are not faulty, but the flywheel 81 itself is faulty, the DC-side controlled braking will be preferentially selected during braking.

[0068] When the grid-side converter 5 and the flywheel 81 body fail, DC-side controlled braking may be selected as a priority.

[0069] When the machine-side converter 6 and the flywheel 81 body fail, only AC-side free braking can be selected.

[0070] A braking control method for a flywheel energy storage system provided in an embodiment of the present invention is applied to a flywheel energy storage system, wherein the flywheel energy storage system comprises: a grid-side converter 5, a machine-side converter 6, a permanent magnet motor 7 and a flywheel 81, wherein a DC-side braking resistor 9 is provided between the grid-side converter 5 and the machine-side converter 6, and an AC-side braking resistor 11 is provided between the machine-side converter 6 and the permanent magnet motor 7; the method comprises: S1, in response to a fault instruction, acquiring monitoring data of the grid-side converter 5 and the machine-side converter 6; S2, determining whether the machine-side converter 6 fails according to the monitoring data; if so, executing step S3; if not, executing step S4; S3, performing AC-side free braking based on the AC-side braking resistor 11 until the flywheel 81 stops by braking; S4, determining that the fault type is a flywheel body fault, and performing DC-side braking based on the DC-side braking resistor 9 until the flywheel 81 stops by braking; the DC-side braking comprises DC-side controlled braking and DC-side free braking. By designing different braking modes and control methods, when the flywheel energy storage system needs to brake, coordinated control can be used to prevent the energy stored in the flywheel 81 from not being released in time, causing the flywheel 81 to lose control and cause wear or damage to the flywheel 81.

[0071] For example 3, please refer to Figure 5 , Figure 5 The present invention is a structural block diagram of a brake control device embodiment of a flywheel energy storage system, which is applied to a flywheel energy storage system. The flywheel energy storage system comprises: a grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device. A DC-side brake resistor is provided between the grid-side converter and the machine-side converter, and an AC-side brake resistor is provided between the machine-side converter and the permanent magnet motor. The device comprises:

[0072] A response module 501, configured to obtain monitoring data of the grid-side converter and the generator-side converter in response to a fault instruction;

[0073] A first state determination module 502 is used to determine whether the machine-side converter fails according to the monitoring data; if so, execute the AC side braking module; if not, execute the DC side braking module;

[0074] An AC side braking module 503, used for performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops;

[0075] The DC side braking module 504 is used to determine that the fault type is a flywheel body fault, and perform DC side braking based on the DC side braking resistor until the flywheel stops; the DC side braking includes DC side controlled braking and DC side free braking.

[0076] In an optional embodiment, it also includes:

[0077] The second state determination module is used to determine whether the grid-side AC device fails based on the monitoring data.

[0078] In an optional embodiment, the AC side braking module 503 includes:

[0079] A circuit breaker adjustment submodule, used to disconnect the circuit breaker between the machine-side converter and the AC-side braking resistor, and close the circuit breaker between the AC-side braking resistor and the motor;

[0080] The first energy consumption submodule is used to consume energy through the back electromotive force of the motor until the flywheel brakes to a stop.

[0081] In an optional embodiment, the DC side braking module 504 includes:

[0082] A converter adjustment submodule, used for disconnecting the switch between the grid-side converter and the generator-side converter, so that the generator-side converter enters a voltage stabilization mode and performs DC side braking according to the command type of the received braking command;

[0083] A second consumption submodule is used for closing the switch of the DC side braking resistor when the command type is a controlled braking command, so that the machine-side converter enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor in the power mode until the flywheel brake stops;

[0084] The third consumption submodule is used to close the switch of the DC side braking resistor when the command type is a free braking command, so that the machine-side converter remains in the voltage stabilization mode and consumes power through the DC side braking resistor in the voltage stabilization mode until the flywheel brake stops.

[0085] An embodiment of the present invention further provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of a braking control method for a flywheel energy storage system as described in any of the above embodiments.

[0086] An embodiment of the present invention further provides a computer storage medium on which a computer program is stored. When the computer program is executed by the processor, the steps of a braking control method for a flywheel energy storage system as described in any of the above embodiments are implemented.

[0087] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0088] In the several embodiments provided in the present application, it should be understood that the methods, devices, electronic devices and storage media disclosed in the present invention can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0089] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0091] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a readable storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned readable storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0092] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A brake control method for a flywheel energy storage system, applied to a flywheel energy storage system, the flywheel energy storage system comprising: A grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, characterized in that a DC-side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC-side braking resistor is provided between the machine-side converter and the permanent magnet motor; the method comprises: S1, in response to a fault instruction, obtaining monitoring data of the grid-side converter and the generator-side converter; S2, determining whether the generator-side converter fails according to the monitoring data; if so, executing step S3; if not, executing step S4; S3, performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops; S4, determining that the fault type is a flywheel body fault, and performing DC side braking based on the DC side braking resistor until the flywheel stops; the DC side braking includes DC side controlled braking and DC side free braking.

2. The brake control method of the flywheel energy storage system according to claim 1, characterized in that: Before step S2, the method further includes: Based on the monitoring data, determine whether the grid-side AC device fails.

3. The brake control method of the flywheel energy storage system according to claim 1, characterized in that: The step S3 comprises: S31, disconnecting the circuit breaker between the machine-side converter and the AC-side braking resistor, and closing the circuit breaker between the AC-side braking resistor and the motor; S32, consuming energy through the back electromotive force of the motor until the flywheel brakes to a stop.

4. The brake control method of the flywheel energy storage system according to claim 1, characterized in that: The step S4 comprises: S41, disconnecting the switch between the grid-side converter and the generator-side converter, causing the generator-side converter to enter a voltage stabilization mode, and performing DC side braking according to the command type of the received braking command; S42, when the command type is a controlled braking command, closing the switch of the DC side braking resistor, the machine-side converter enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor in the power mode until the flywheel brake stops; S43, when the command type is a free braking command, the switch of the DC side braking resistor is closed, the machine-side converter remains in the voltage stabilization mode, and consumes power through the DC side braking resistor in the voltage stabilization mode until the flywheel brake stops.

5. A brake control device for a flywheel energy storage system, applied to a flywheel energy storage system, the flywheel energy storage system comprising: A grid-side converter, a machine-side converter, a permanent magnet motor and a flywheel energy storage device, characterized in that a DC-side braking resistor is provided between the grid-side converter and the machine-side converter, and an AC-side braking resistor is provided between the machine-side converter and the permanent magnet motor; the device comprises: A response module, configured to obtain monitoring data of the grid-side converter and the generator-side converter in response to a fault instruction; A first state determination module, used to determine whether the machine-side converter fails according to the monitoring data; if so, execute the AC side braking module; if not, execute the DC side braking module; An AC side braking module, used for performing AC side free braking based on the AC side braking resistor until the flywheel brake of the flywheel energy storage device stops; The DC side braking module is used to determine that the fault type is a flywheel body fault, and perform DC side braking based on the DC side braking resistor until the flywheel brake stops; the DC side braking includes DC side controlled braking and DC side free braking.

6. The brake control device of the flywheel energy storage system according to claim 5, characterized in that: Also includes: The second state determination module is used to determine whether the grid-side AC device fails based on the monitoring data.

7. The brake control device of the flywheel energy storage system according to claim 5, characterized in that: The AC side braking module comprises: A circuit breaker adjustment submodule, used for disconnecting the circuit breaker between the machine-side converter and the AC-side braking resistor, and closing the circuit breaker between the AC-side braking resistor and the motor; The first energy consumption submodule is used to consume energy through the back electromotive force of the motor until the flywheel brakes to a stop.

8. The brake control device of the flywheel energy storage system according to claim 5, characterized in that: The DC side braking module comprises: A converter adjustment submodule, used for disconnecting the switch between the grid-side converter and the generator-side converter, so that the generator-side converter enters a voltage stabilization mode and performs DC side braking according to the command type of the received braking command; A second consumption submodule is used for closing the switch of the DC side braking resistor when the command type is a controlled braking command, so that the machine-side converter enters the power mode from the voltage stabilization mode, and consumes power through the DC side braking resistor in the power mode until the flywheel brake stops; The third consumption submodule is used to close the switch of the DC side braking resistor when the command type is a free braking command, so that the machine-side converter remains in the voltage stabilization mode and consumes power through the DC side braking resistor in the voltage stabilization mode until the flywheel brake stops.

9. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 4 is executed.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 4 is executed.

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