High-speed energy storage flywheel magnetic suspension active safety system and control method

Abstract

The invention discloses a magnetic suspension active safety system of a high-speed energy storage flywheel, and aims to solve the safety problem caused by power loss of a circuit during working of an electromagnetic bearing of the high-speed energy storage flywheel. The content comprises circuit topology structures in different switch on-off states and five working states and control logics corresponding to the circuit topology structures respectively. According to the method, the defects in the prior art are overcome, the possibility that the high-speed energy storage flywheel is shut down due to faults is greatly reduced, and the time and economic cost caused by magnetic bearing circuit faults or power grid faults can be reduced.

Description

Technical Field

[0001] The invention relates to the field of operation reliability assurance of a high-speed energy storage flywheel, and in particular to an active safety system and a control method for a magnetic suspension bearing of a high-speed energy storage flywheel. Background Art

[0002] High-speed energy storage flywheel devices are generally composed of high-speed energy storage flywheel rotors, bearings, motors, converters, and auxiliary equipment such as vacuum and cooling. Magnetic bearings are high-performance bearings that use magnetic field forces to suspend the rotor in the air without mechanical friction. They can achieve active control and have the characteristics of high speed, no mechanical friction, and no lubrication. They are widely used in flywheel energy storage devices. At present, patents in the field of magnetic bearings for flywheel energy storage are mostly concentrated on the invention of structural bodies and control methods and strategies. Publication No. CN116191502A invented a power-off self-protection control method and system for a flywheel energy storage auxiliary system, but this invention is only effective for power outages caused by power grid faults, and cannot deal with situations where the flywheel system is shut down or equipment is damaged or even personal safety accidents occur due to power failures in the flywheel internal circuit.

[0003] As an important component supporting the stable operation of high-speed rotors, magnetic bearings are of great significance to the safe operation of flywheel devices. Magnetic bearing failures mainly include power circuit failures, magnetic bearing coil failures, sensor failures, and controller failures. Since the failure probability of power electronic devices is higher, power circuit failures are most likely to occur compared to other failures. If certain components in its circuit fail due to a fault, the magnetic bearing will instantly lose its original supporting capacity, which may cause serious damage to the system. Therefore, the present invention provides a high-speed energy storage flywheel magnetic suspension active safety system and control method, which greatly reduces the possibility of high-speed energy storage flywheel shutdown due to failures and solves the shortcomings existing in the prior art. Summary of the invention

[0004] The present invention aims to solve the problem of safe operation of high-speed flywheels in the prior art, and thus proposes a high-speed energy storage flywheel magnetic levitation active safety system, including a power grid, a switch, a transformer, a filter, a converter, a bidirectional motor, a magnetic levitation magnetic bearing, a flywheel, a displacement sensor, a current detection device, a power amplifier, a controller, a rectifier, a battery, a battery controller, an inverter, and vacuum and cooling auxiliary equipment; in the circuit, one path of the power grid is connected to the first bidirectional motor after passing through a transformer, a switch S0, and a converter, and filters are provided at both ends of the converter to reduce harmonics; the other path of the power grid is obtained by voltage transformation and rectification A DC circuit, and then the DC circuit, the first controller, the first power amplifier and the fuse, and the magnetic bearing form a magnetic bearing circuit. At the same time, the DC circuit is converted into three-phase electricity through an inverter to power auxiliary equipment such as vacuum and cooling. In addition to being connected to the grid side, the first bidirectional motor is also connected to the DC circuit on the grid side through a transformer and a converter. At the same time, the first bidirectional motor is also connected to the second bidirectional motor of the second flywheel through a transformer and a switch S3. The battery is connected to the DC circuit of the grid-side DC power supply through a battery controller and a switch S4. A consumer load that can be connected is also provided in the return circuit.

[0005] On the other hand, the present invention also provides a control method for a high-speed energy storage flywheel magnetic levitation active safety system, which is used to control the high-speed energy storage flywheel magnetic levitation active safety system described in Qianwen, and takes the current in the magnetic levitation bearing circuit being 0 within time t as a judgment condition. When this condition occurs in the magnetic levitation bearing circuit in the circuit, the first controller is converted into a second power amplifier connected to the magnetic levitation bearing, and the switch S4 is quickly closed and connected to the main circuit.

[0006] Furthermore, when the magnetic bearing circuit fails but the power grid is normal, the first controller is converted into a second power amplifier connected to the magnetic bearing, and the switch S4 is connected to the main circuit, and maintenance is performed under the operation state of the high-speed energy storage flywheel; after the maintenance is completed, the first controller is converted into the first power amplifier connected to the magnetic bearing for operation.

[0007] Furthermore, when a power grid fails, switch S2 is connected to the main circuit. If the speed of the first flywheel is higher than the operating speed, the speed of the first bidirectional motor gradually decreases and enters the power generation state. The magnetic bearing and vacuum and cooling auxiliary equipment are all powered by batteries. At the same time, the first bidirectional motor generates electricity to charge the battery.

[0008] Furthermore, when a power grid fails, switch S2 is connected to the main circuit. If the speed of the first flywheel is higher than the operating speed, the speed of the first bidirectional motor gradually decreases and enters the power generation state. If it is detected that the power of the second flywheel is low, switch S3 is closed to supply the energy of the first flywheel to the second flywheel with lower energy in the same array until the high-speed energy storage flywheel rotor is lower than the minimum operating speed, and then the consumption load is connected to the circuit to stop the flywheel system.

[0009] In the present invention, the circuit has a total of 5 access states. State 1: The magnetic suspension bearing circuit is normal and the power grid state is normal. At this time, the main circuit is connected, and switches S2, S3 and S4 are all disconnected. The first power amplifier and the third power amplifier operate normally. The motor, magnetic suspension bearing, vacuum, cooling and other auxiliary equipment are all powered by the power grid, and the high-speed energy storage flywheel system operates normally, and the state is not affected. State 2: The main circuit magnetic suspension bearing circuit fails but the power grid state is normal. At this time, S4 is connected to the main circuit, and the controller switches to the second power amplifier circuit to control the magnetic suspension bearing. The motor, magnetic suspension bearing, vacuum, cooling and other auxiliary equipment are actually powered by the power grid, and the high-speed energy storage flywheel system operates normally, and the state is not affected. State 3: The main circuit magnetic suspension bearing circuit failure is caused by a power grid failure. At this time, switch S2 is connected to the main circuit, and the first bidirectional motor of the first flywheel gradually reduces the speed of operation. The magnetic suspension bearing and vacuum, cooling and other auxiliary equipment are all powered by batteries. At the same time, the first bidirectional motor generates electricity to supply the battery for charging, and the high-speed energy storage flywheel enters the power generation state. Switch state 4: The main circuit magnetic bearing circuit failure is caused by a power grid failure. Switches S2 and S3 are both connected to the circuit. At this time, based on state 3, the first flywheel can supply excess energy to other flywheels in the array, such as the second flywheel. State 5: When the power grid fails, the actual speed of the high-speed energy storage flywheel is lower than the minimum operating speed after a period of power generation. The consumption load is connected and the flywheel system stops running. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A circuit topology diagram showing the active safety protection of the high-speed flywheel magnetic suspension in the present invention.

[0011] Figure 2 A control logic block diagram showing the active safety protection of the high-speed flywheel magnetic suspension in the present invention. DETAILED DESCRIPTION

[0012] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the protection scope of the present invention.

[0013] Figure 1The entire high-speed energy storage flywheel magnetic levitation active safety system consists of multiple key components, including power grid, switch, transformer, filter, converter, bidirectional motor, magnetic levitation magnetic bearing, flywheel, displacement sensor, current detection device, power amplifier, controller, rectifier, battery, battery controller, inverter, vacuum, cooling auxiliary equipment, etc. These components are connected through complex circuits to jointly realize the stable operation and fault protection function of the system.

[0014] Grid access and power distribution.

[0015] Grid access: The grid is the main power source of the system. The voltage is adjusted by the transformer and then divided into two routes for transmission. The first power supply: After passing through the transformer, switch S0, and converter, it is connected to the first bidirectional motor. Filters are provided at both ends of the converter to reduce harmonics and ensure stable current transmission. The second power supply is transformed and rectified to obtain a DC circuit. This DC circuit, the controller (first controller), the power amplifier (first power amplifier), the fuse, and the magnetic bearing form a magnetic bearing circuit. At the same time, the DC circuit is also converted into three-phase electricity through the inverter to power auxiliary equipment such as vacuum and cooling.

[0016] A bidirectional motor is connected to the flywheel.

[0017] In addition to being connected to the grid side, the first bidirectional motor is also connected to the grid-side DC circuit through a transformer and a converter, realizing bidirectional energy transmission. In addition, the first bidirectional motor is also connected to the second bidirectional motor of the second flywheel through a transformer and a switch S3, realizing energy transfer between flywheels. As the energy storage element of the system, the flywheel achieves contactless suspension through magnetic suspension magnetic bearings, reducing mechanical friction and energy loss. In the system, the flywheel can be in an energy storage state, a power generation state, or a holding state, and can be flexibly adjusted according to the grid dispatching instructions and system requirements.

[0018] Batteries and emergency power supply.

[0019] It is connected to the grid-side DC circuit through the battery controller and switch S4. Under normal circumstances, the battery is in a charging state and provides backup power for the system. In case of emergency power supply, when the grid fails or the magnetic bearing circuit fails, the battery is quickly connected to the main circuit to provide power support for the magnetic bearing and auxiliary equipment. At the same time, if the flywheel speed is higher than the working speed, the bidirectional motor can also generate electricity to charge the battery, thus extending the emergency power supply time.

[0020] Fault detection and protection mechanism.

[0021] The current detection device monitors the current changes in the magnetic bearing circuit in real time. If the current is detected to be continuously 0 within a certain time interval t, it is judged that the magnetic bearing has a power failure. The controller and the power amplifier, according to the signal fed back by the current detection device, the controller quickly switches to the backup power amplifier (such as the second power amplifier) ​​to continue to control the operation of the magnetic bearing. At the same time, a fault alarm is issued to prompt the operator to repair the fault. Switch control, by controlling the on and off states of switches S2, S3, and S4, different operating modes and fault protection strategies of the system are realized. For example, when the power grid fails, switches S2 and S3 are closed to realize the power generation and energy transfer of the flywheel; when the magnetic bearing circuit fails, switch S4 is closed and the battery is connected for emergency power supply.

[0022] Auxiliary equipment and operating environment.

[0023] Vacuum and cooling auxiliary equipment provide the necessary operating environment for the flywheel. The vacuum equipment is used to reduce air resistance and improve the flywheel's energy storage efficiency; the cooling equipment is used to dissipate heat and prevent the system from overheating and damage. The displacement sensor monitors the position change of the flywheel in real time and provides feedback signals to the controller to ensure the stable operation of the flywheel.

[0024] See also Figure 2 , shows the control logic block diagram.

[0025] When the system starts, it first enters the initial state. In this state, all switches (S0, S1, S2, S3, S4) are in the preset position, usually S0 and S1 are closed, S2, S3, S4 are disconnected. At this time, the power grid is powered normally, the high-speed energy storage flywheel and its auxiliary equipment (such as vacuum pumps, cooling equipment, etc.) are in normal working state, and the magnetic bearing is powered by the power grid through the controller and power amplifier.

[0026] The system continuously monitors the current in the magnetic bearing circuit. This is an important basis for determining whether the magnetic bearing has lost power. If the current is detected to be 0 continuously within a certain time interval t, the system considers that the magnetic bearing has lost power and immediately enters the fault handling process.

[0027] The troubleshooting process is as follows:

[0028] 1. The power grid is normal, but the magnetic bearing circuit is faulty. When a magnetic bearing circuit fault is detected but the power grid is normal, the system performs the following operations:

[0029] a) Immediately close switch S4 and connect the battery to the magnetic bearing circuit to provide power support for the magnetic bearing.

[0030] b) The controller switches to a backup power amplifier (such as the second power amplifier) ​​to continue controlling the operation of the magnetic bearing.

[0031] c) The system remains in operation and issues a fault alarm, prompting the operator to inspect and repair the magnetic bearing circuit.

[0032] d) During the maintenance period, if the grid is in good condition, both the battery and the grid-side DC circuit can supply power to the magnetic bearing to ensure the normal operation of the flywheel.

[0033] 2. Grid failure. When a grid failure is detected, the system performs the following operations:

[0034] a) Immediately close switch S2 to connect the bidirectional motor to the circuit and prepare to start generating electricity.

[0035] b) If the flywheel speed is higher than the working speed, the bidirectional motor starts to generate electricity. The generated AC power is converted into DC power through a transformer and converter to charge the battery and supply the magnetic bearing and auxiliary equipment.

[0036] c) If it is detected that the power of other flywheels (such as the second flywheel) is low at this time, the switch S3 can be closed to supply the excess energy of the current flywheel (such as the first flywheel) to other flywheels to maintain the overall stability of the flywheel array.

[0037] d) If the flywheel speed drops below the minimum operating speed, the system will connect to the consumption load, causing the flywheel to slow down and stop, and all systems will stop working.

[0038] The grid restoration and system restart process is as follows:

[0039] When the grid fault is repaired, the system performs the following operations to resume normal operation:

[0040] a) Open switches S2 and S4 to disconnect the bidirectional motor from the battery.

[0041] b) Reclose switches S0 and S1 to restore grid power.

[0042] c) The controller switches back to the original power amplifier (such as the first power amplifier) ​​to continue controlling the operation of the magnetic bearing.

[0043] d) Carry out a comprehensive inspection of the system to ensure that all equipment is in normal working condition.

[0044] e) If the inspection is completed and the magnetic bearing circuit returns to normal, disconnect switch S4 and restore direct power supply from the grid.

[0045] After all faults are handled and the system resumes normal operation, the system enters the end state. At this time, all equipment is in normal working state, and the high-speed energy storage flywheel continues to operate according to the grid dispatch instructions.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-speed energy storage flywheel magnetic suspension active safety system, characterized in that: The invention comprises a power grid, a switch, a transformer, a filter, a converter, a bidirectional motor, a magnetic suspension magnetic bearing, a flywheel, a displacement sensor, a current detection device, a power amplifier, a controller, a rectifier, a battery, a battery controller, an inverter, and vacuum and cooling auxiliary equipment; one path of the power grid is connected to the first bidirectional motor through a transformer, a switch S0 and a converter, and filters are arranged at both ends of the converter to reduce harmonics; the other path of the power grid is transformed and rectified to obtain a DC circuit, and the DC circuit, the first controller, the first power amplifier and the fuse and the magnetic suspension magnetic bearing form a magnetic suspension bearing circuit, and the DC circuit is converted into three-phase electricity through an inverter to supply power to the vacuum and cooling auxiliary equipment; the first bidirectional motor is also connected to the DC circuit through a transformer and a converter, and the first bidirectional motor is also connected to the second bidirectional motor of the second flywheel through a transformer and a switch S3; the battery is connected to the DC circuit through a battery controller and a switch S4; and a consumer load that can be connected is also arranged in the circuit.

2. A control method for a high-speed energy storage flywheel magnetic levitation active safety system, used to control the high-speed energy storage flywheel magnetic levitation active safety system according to claim 1, characterized in that: The current in the magnetic bearing circuit being 0 within time t is used as a judgment condition. When this condition occurs in the magnetic bearing circuit in the circuit, the first controller is converted into a second power amplifier connected to the magnetic bearing, and the switch S4 is quickly closed and connected to the main circuit.

3. The control method of a high-speed energy storage flywheel magnetic suspension active safety system according to claim 2 is characterized in that: When the magnetic bearing circuit fails but the power grid is normal, the first controller is converted to the second power amplifier connected to the magnetic bearing, and the switch S4 is connected to the main circuit, and maintenance is performed under the operation state of the high-speed energy storage flywheel; after the maintenance is completed, the first controller is converted to the first power amplifier connected to the magnetic bearing for operation.

4. The control method of a high-speed energy storage flywheel magnetic suspension active safety system according to claim 2 is characterized in that: When the power grid fails, switch S2 is connected to the main circuit. If the speed of the first flywheel is higher than the working speed, the speed of the first bidirectional motor gradually decreases and enters the power generation state. The magnetic bearing and vacuum and cooling auxiliary equipment are all powered by batteries. At the same time, the first bidirectional motor generates electricity to charge the battery.

5. The control method of a high-speed energy storage flywheel magnetic suspension active safety system according to claim 2 is characterized in that: When the power grid fails, switch S2 is connected to the main circuit. If the speed of the first flywheel is higher than the working speed, the speed of the first bidirectional motor gradually decreases and enters the power generation state. If it is detected that the power of the second flywheel is low, switch S3 is closed to supply the energy of the first flywheel to the second flywheel with lower energy in the same array until the high-speed energy storage flywheel rotor is lower than the minimum working speed, then the consumption load is connected to the circuit to stop the flywheel system.

Images