Distributed magnetic suspension flywheel network energy storage system and grid connection method thereof

Abstract

The invention belongs to the technical field of magnetic suspension flywheel network energy storage systems, and discloses a distributed magnetic suspension flywheel network energy storage system and a grid connection method thereof. The system is composed of a plurality of magnetic suspension flywheel energy storage units, and each unit comprises a flywheel, a sealed flywheel chamber, an electromagnetic supporting device, a motor / generator and the like. Through the combination of the electromagnetic bearing and the air cushion support, the supporting problem caused by heavy weight of a medium-low speed flywheel is solved, the mechanical friction loss is reduced, and the energy conversion efficiency is improved. The flywheel chamber adopts an underground sealing structure, so that the environmental adaptability is enhanced. The system is provided with a power electronic control device, a bidirectional DC-AC converter and an auxiliary cooling and lubricating system, and multi-unit cooperative control and efficient energy management are achieved. The grid-connected method comprises the four steps of system detection, synchronous adjustment, grid-connected connection and operation monitoring, output electric energy is ensured to be synchronous with a power grid through a PWM modulation technology, bidirectional electric energy transmission is supported, the response speed is high, and the transmission loss of the distributed energy storage system is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic levitation flywheel network energy storage systems, and in particular to a distributed magnetic levitation flywheel network energy storage system and its grid connection method. Background Technique

[0002] In the existing field of high-speed flywheel energy storage, the mass of high-speed flywheel energy storage is relatively light, and the energy storage capacity is improved by increasing the rotation speed. The main disadvantage is that it is difficult to increase the rotation speed. At present, the rotation speed has reached the limit of the flywheel material, so it has reached a bottleneck period.

[0003] The characteristics of medium and low-speed flywheel energy storage are different from those of high-speed flywheels. The present invention mainly focuses on the field of medium and low-speed flywheels. The main problem of existing medium and low-speed flywheel energy storage is that the flywheel is too heavy to support, which poses high requirements on the bearings. This further restricts the increase in the weight of medium and low-speed flywheels. The existing technology uses the method of installing permanent magnets above the flywheel to share the pressure of the flywheel on the bearings, but the suction force of the permanent magnets is still too small. At the same time, the existing energy storage systems adopt a centralized energy storage method. When dealing with the access of large-scale distributed renewable energy, there are problems such as large energy transmission losses and slow response speeds. When the distance between the renewable energy power generation point and the energy storage device is far, the loss of electric energy during transmission will increase significantly, reducing the energy utilization efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a distributed magnetic levitation flywheel network energy storage system and its grid connection method to solve the problems raised in the above background technique.

[0005] To achieve the above object, the present invention provides the following technical solutions: A distributed magnetic levitation flywheel network energy storage system, comprising a plurality of magnetic levitation flywheel energy storage units, each of the energy storage units including: a flywheel, a flywheel chamber, and an electromagnetic support device; the flywheel chamber is installed inside a circular concrete well on the ground and fixed by a bracket, and a cover is provided on the wellhead, and the flywheel chamber is a sealed metal container; a flywheel is installed inside the flywheel chamber, and a rotor shaft is provided in the middle of the flywheel; a combined bearing is installed below the high-precision rotor piece on the flywheel chamber, and a flywheel synchronous stable sealing frame is installed on the combined bearing. The combined bearing is a bearing integrating a thrust bearing and a radial bearing, and can be of a multi-jaw type or a sector-shaped tile type. The spokes of the flywheel synchronous stable sealing frame are of a breathable structure to ensure that the air cushion pressure can be transmitted to the high-precision rotor piece at the bottom of the vacuum pump; mutually cooperating brush seals are installed on the high-precision rotor piece and the peripheral metal ring of the flywheel synchronous stable sealing frame, and two O-ring seals are provided on the outer side of the peripheral metal ring of the flywheel synchronous stable sealing frame, and the O-ring seals are connected to the inner wall of the flywheel chamber; an electromagnetic support device and a radial electromagnetic bearing are provided at the bottom of the flywheel chamber, and a radial electromagnetic bearing and an axial electromagnetic bearing are installed on the upper part of the flywheel chamber; a gear disc is installed on the upper part of the rotor shaft, an electric / generator is also installed on the upper part of the flywheel chamber, a gear is provided on the upper part of the electric / generator, and the gear disc meshes with the gear on the upper part of the electric / generator; an air compressor and a vacuum pump are also provided outside the upper part of the flywheel chamber. The air outlet of the air compressor is at the bottom of the flywheel chamber below the brush seal, and the air extraction port of the vacuum pump is at the upper part of the flywheel chamber above the brush seal.

[0006] Further, it further includes a power electronic control device, a frequency conversion / inversion controller, a power converter, and an auxiliary system.

[0007] Further, the power electronic control device includes a microprocessor, a signal acquisition module, and a drive module. The signal acquisition module is used to acquire the operating parameters of the flywheel main structure, and the microprocessor controls the system through the drive module according to the acquired parameters;

[0008] Further, the signal acquisition module includes a speed sensor, a current sensor, and a voltage sensor, which are respectively used to acquire the speed of the flywheel, the current of the electromagnetic support device and the radial electromagnetic bearing and the axial electromagnetic bearing, and the voltage of the electric / generator.

[0009] Further, the frequency conversion / inversion controller adopts PWM modulation technology and can accurately adjust the voltage, frequency, and phase output by the electric / generator.

[0010] Further, the power converter is a bidirectional DC-AC converter, which can realize the bidirectional electric energy conversion between the distributed magnetic levitation flywheel network energy storage system and the power grid.

[0011] Furthermore, the auxiliary system includes a cooling system and a lubrication system. The cooling system is used to cool the motor / generator and the electromagnetic support device, and the lubrication system is used to lubricate the combined bearing. The cooling system adopts a water-cooling method and includes a coolant circulation pump, a radiator, and cooling pipes. The coolant cools the motor / generator and the electromagnetic support device through the cooling pipes.

[0012] A grid connection method for a distributed magnetic levitation flywheel network energy storage system includes the following steps:

[0013] Step 1: System detection and preparation. Perform status detection on each flywheel main structure in the distributed magnetic levitation flywheel network energy storage system, including detecting the rotational speed of the flywheel, the working states of the electromagnetic support device, the radial electromagnetic bearing, and the axial electromagnetic bearing, and the performance of the motor / generator. At the same time, detect the working states of the power electronic control device, the frequency conversion / inversion controller, and the power converter to ensure that the entire system is in a normal operable state.

[0014] Step 2: Synchronous adjustment. Through the power electronic control device and the frequency conversion / inversion controller, adjust the motor / generators of each flywheel main structure in the distributed network to make the voltage, frequency, and phase output by each flywheel main structure synchronous with the voltage, frequency, and phase of the power grid.

[0015] Step 3: Grid connection. When the voltage, frequency, and phase output by each flywheel main structure are synchronized with the power grid, connect the distributed magnetic levitation flywheel network energy storage system to the power grid through the power converter to realize the system's power transmission to the power grid or power absorption from the power grid.

[0016] Step 4: Operation monitoring and adjustment. During the grid-connected operation, continuously monitor the operation parameters of the distributed magnetic levitation flywheel network energy storage system and the power grid, including voltage, current, and power. According to the monitoring results, through the power electronic control device and the frequency conversion / inversion controller, real-time adjust the operation states of each flywheel main structure to ensure the stable operation of the system and power quality, and at the same time reasonably distribute the energy output or input of each flywheel main structure according to the power grid's demand.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] The application of the magnetic levitation technology in the present invention reduces the mechanical friction loss during the rotation of the flywheel and improves the energy conversion efficiency. The flywheel can stably operate for a long time under high-speed rotation, efficiently convert electrical energy into mechanical energy for storage, and quickly convert mechanical energy into electrical energy for release when needed. It has a fast response speed and can meet the power grid's demand for rapid regulation.

[0019] The flywheel chamber adopts a sealed metal container and is installed inside a circular concrete well on the ground. This structural design can effectively protect the flywheel from external environmental factors such as dust and moisture, improving the reliability and stability of the system.

[0020] The use of electromagnetic support devices and electromagnetic bearings avoids the wear and failure problems of traditional mechanical bearings, reduces the maintenance workload and repair costs, extends the service life of the system, and forms an air cushion support at the bottom. The air cushion flywheel can greatly improve the flywheel energy storage capacity; through the system detection and preparation steps, a comprehensive inspection of each flywheel main structure and related control devices is carried out to ensure that the system is in a normal operable state, avoiding grid connection accidents caused by equipment failures, and improving the safety and reliability of grid connection; the synchronous adjustment step synchronizes the voltage, frequency, and phase output by each flywheel main structure with the power grid, ensuring the smooth access of electric energy, reducing the impact on the power grid, and maintaining the stable operation of the power grid. During the grid connection operation, by continuously monitoring the operation parameters of the system and the power grid and adjusting the operation state of each flywheel main structure in real time according to the monitoring results, the quality of the output electric energy can be effectively controlled to ensure that parameters such as voltage and frequency meet the requirements of the power grid. Brief Description of the Drawings

[0021] Figure 1 It is a schematic flow chart of the grid connection method of the present invention;

[0022] Figure 2 It is a schematic diagram of the magnetic levitation flywheel energy storage unit of the present invention;

[0023] Figure 3 It is a schematic layout diagram of the electromagnetic support device of the present invention.

[0024] Reference numerals in the figures: 1, flywheel; 2, vacuum pump; 3, rotor shaft; 4, radial electromagnetic bearing; 5, flywheel chamber; 6, air compressor; 7, flywheel synchronous stable seal frame; 8, gear disc; 9, motor / generator; 10, combined bearing; 11, axial electromagnetic bearing; 12, cover; 13, O-ring seal; 14, brush type steam seal; 15, high-precision rotor sheet; 16, electromagnetic support device. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Please refer to Figure 1—3, the present invention provides a technical solution: a distributed magnetic levitation flywheel network energy storage system, including a plurality of magnetic levitation flywheel energy storage units. Each energy storage unit includes: a flywheel 1, a flywheel chamber 5, and an electromagnetic support device 16; the flywheel chamber 5 is installed inside a circular concrete well on the ground and fixed by brackets, and a cover 12 is provided at the wellhead. The flywheel chamber 5 is a sealed metal container; the flywheel 1 is installed inside the flywheel chamber 5, and a rotor shaft 3 is provided in the middle of the flywheel 1; a combined bearing 10 is installed below the high-precision rotor piece 15 on the flywheel chamber 5, and a flywheel synchronous stable sealing frame 7 is installed on the combined bearing 10. The combined bearing 10 is a bearing integrating a thrust bearing and a radial bearing, and can adopt a multi-jaw type or a sector tile type. The spokes of the flywheel synchronous stable sealing frame 7 are breathable structures to ensure that the air cushion pressure can be transmitted to the high-precision rotor piece 15 at the bottom of the vacuum pump 2; mutually cooperating brush-type steam seals 14 are installed on the high-precision rotor piece 15 and the peripheral metal ring of the flywheel synchronous stable sealing frame 7, and two O-ring seals 13 are provided on the outer side of the peripheral metal ring of the flywheel synchronous stable sealing frame 7. The O-ring seals 13 are connected to the inner wall of the flywheel chamber 5; an electromagnetic support device 16 and a radial electromagnetic bearing 4 are provided at the bottom of the flywheel chamber 5, and a radial electromagnetic bearing 4 and an axial electromagnetic bearing 11 are installed on the upper part of the flywheel chamber 5; a gear disk 8 is installed on the upper part of the rotor shaft 3, and an electric / generator 9 is also installed on the upper part of the flywheel chamber 5. There is a gear on the upper part of the electric / generator 9, and the gear disk 8 meshes with the gear on the upper part of the electric / generator 9; an air compressor 6 and a vacuum pump 2 are also provided outside the flywheel chamber 5. The air outlet of the air compressor 6 is at the bottom of the flywheel chamber 5 below the brush-type steam seal 14, and the air extraction port of the vacuum pump 2 is at the upper part of the flywheel chamber 5 above the brush-type steam seal 14.

[0027] It also includes a power electronic control device, a frequency conversion / inversion controller, a power converter, and an auxiliary system.

[0028] The power electronic control device includes a microprocessor, a signal acquisition module, and a drive module. The signal acquisition module is used to acquire the operating parameters of the flywheel main structure. The microprocessor controls the system through the drive module according to the acquired parameters; the signal acquisition module includes a speed sensor, a current sensor, and a voltage sensor, which are respectively used to acquire the speed of the flywheel 1, the currents of the electromagnetic support device 16, the radial electromagnetic bearing 4, and the axial electromagnetic bearing 11, and the voltage of the electric / generator 9.

[0029] The speed sensor is installed near the flywheel 1 to acquire the speed of the flywheel 1; the current sensor is installed in the circuits of the electromagnetic support device 10, the radial electromagnetic bearing 4, and the axial electromagnetic bearing 11 to acquire current data; the voltage sensor is installed in the circuit of the electric / generator 9 to acquire voltage data. The operating parameters acquired by the signal acquisition module are transmitted to the microprocessor, and the microprocessor precisely controls the system through the drive module according to these parameters.

[0030] The variable frequency / inverter controller adopts PWM modulation technology and can accurately adjust the voltage, frequency and phase output by the motor / generator 9. The power converter is a bidirectional DC-AC converter, which can realize the bidirectional power conversion between the distributed magnetic levitation flywheel network energy storage system and the power grid.

[0031] The auxiliary system includes a cooling system and a lubrication system. The cooling system is used to cool the motor / generator 9 and the electromagnetic support device 16, and the lubrication system is used to lubricate the combined bearing 10; The cooling system adopts the water-cooling method and includes a coolant circulation pump, a radiator and cooling pipes. The coolant cools the motor / generator 9 and the electromagnetic support device 16 through the cooling pipes.

[0032] When the system starts, the axial electromagnetic bearing 12 is energized to generate a magnetic field, which generates an upward acting force on the flywheel 1, controlling the flywheel 1 to break away from the contact with the initial support structure. At the same time, the air compressor 6 starts to work, and its air outlet inflates the bottom of the flywheel chamber 5 under the brush type steam seal 8 to form an air cushion. The air storage tank of the piston type air compressor 6 supplies air to the air cushion, so that the air pressure in the air cushion is maintained within the set range, and jointly bears the weight of the flywheel 1 with the axial electromagnetic bearing 12. The radial electromagnetic bearing 4 and the electromagnetic support device 10 respectively provide supporting forces in the radial and bottom directions to ensure the stability of the flywheel 1 during rotation. By the power electronic control device, the data of the current sensor is monitored in real time, and the currents of the electromagnetic support device 10, the radial electromagnetic bearing 4 and the axial electromagnetic bearing 11 are dynamically adjusted to meet the support requirements of the flywheel 1 under different rotational speeds and loads.

[0033] After the vacuum pump 2 starts, the upper part of the flywheel chamber 5 above the brush type steam seal 8 is evacuated. The purpose of this is to reduce the air resistance when the flywheel 1 rotates and reduce the energy loss. The combined use of the brush type steam seal 8 and the O-ring 13 effectively prevents the gas in the lower air-filled area of the flywheel chamber 5 from leaking into the upper vacuum area, ensuring the stability of the vacuum environment.

[0034] When energy needs to be stored, the power grid supplies power to the motor / generator 9. The motor / generator 9 operates as a motor and drives the rotor shaft 3 and the flywheel 1 to accelerate rotation through the gear disc 8, converting electrical energy into the kinetic energy of the flywheel 1 for storage. When energy needs to be released, the high-speed rotating flywheel 1 drives the motor / generator 9 to operate as a generator, converting kinetic energy into electrical energy for output. The variable frequency / inverter controller accurately adjusts the voltage, frequency and phase output by the motor / generator 9 according to the system requirements and the power grid status.

[0035] A grid connection method for a distributed magnetic levitation flywheel network energy storage system includes the following steps:

[0036] Step 1: System Detection and Preparation Detect the status of each flywheel main structure in the distributed magnetic levitation flywheel network energy storage system, including detecting the rotational speed of Flywheel 1, the working status of the electromagnetic support device 16, the radial electromagnetic bearing 4, and the axial electromagnetic bearing 11, and the performance of the motor / generator 9. At the same time, detect the working status of the power electronic control device, the frequency conversion / inversion controller, and the power converter to ensure that the entire system is in a normal operable state;

[0037] Step 2: Synchronous Regulation Through the power electronic control device and the frequency conversion / inversion controller, regulate the motor / generator 9 of each flywheel main structure in the distributed network to make the voltage, frequency, and phase output by each flywheel main structure synchronous with the voltage, frequency, and phase of the power grid;

[0038] Step 3: When the voltage, frequency, and phase output by each flywheel main structure are synchronized with the power grid, connect the distributed magnetic levitation flywheel network energy storage system to the power grid through a bidirectional DC-AC power converter. During the connection process, closely monitor the changes in current and voltage at the moment of connection to ensure a smooth connection and avoid impacting the power grid and the energy storage system. After the connection is completed, control the energy storage system to deliver electric energy to the power grid or absorb electric energy from the power grid according to actual needs;

[0039] Step 4: During the grid-connected operation process, use various sensors (such as rotational speed sensors, current sensors, voltage sensors, etc.) and monitoring devices to continuously monitor the operation parameters of the distributed magnetic levitation flywheel network energy storage system and the power grid, including voltage, current, power, etc. Transmit the monitoring data to the microprocessor of the power electronic control device in real time. The microprocessor adjusts the operation status of each flywheel main structure in real time through the drive module and the frequency conversion / inversion controller according to the monitoring results. When the power grid voltage fluctuates or the power demand changes, adjust the output of the motor / generator 14 in a timely manner to ensure the stable operation of the system and the power quality. At the same time, reasonably allocate the energy output or input of each flywheel main structure according to the overall demand of the power grid to improve the energy utilization efficiency.

Claims

1. A distributed magnetic levitation flywheel network energy storage system, characterized in that, Multiple magnetic levitation flywheel energy storage units, each energy storage unit comprising: a flywheel (1), a flywheel chamber (5), and an electromagnetic support device (16); the flywheel chamber (5) is installed inside a circular concrete well on the ground and fixed by a bracket, and a cover (12) is provided at the wellhead, and the flywheel chamber (5) is a sealed metal container; a flywheel (1) is installed inside the flywheel chamber (5), and a rotor shaft (3) is provided in the middle of the flywheel (1); a combined bearing (10) is installed below a high-precision rotor plate (15) on the flywheel chamber (5), and a flywheel synchronous stable sealing frame (7) is installed on the combined bearing (10), and the combined bearing (10) is a bearing integrating a thrust bearing and a radial bearing, and can adopt a multi-jaw type or a sector-shaped tile type, and the spokes of the flywheel synchronous stable sealing frame (7) are of a breathable structure to ensure that the air cushion pressure can be transmitted to the high-precision rotor plate (15) at the bottom of the vacuum pump (2); mutually cooperating brush seals (14) are installed on the high-precision rotor plate (15) and the peripheral metal ring of the flywheel synchronous stable sealing frame (7), and two O-ring seals (13) are provided on the outer side of the peripheral metal ring of the flywheel synchronous stable sealing frame (7), and the O-ring seals (13) are connected to the inner wall of the flywheel chamber (5); an electromagnetic support device (16) and a radial electromagnetic bearing (4) are provided at the bottom of the flywheel chamber (5), and a radial electromagnetic bearing (4) and an axial electromagnetic bearing (11) are installed on the upper part of the flywheel chamber (5); a gear disk (8) is installed on the upper part of the rotor shaft (3), an electric / generator (9) is also installed on the upper part of the flywheel chamber (5), a gear is provided on the upper part of the electric / generator (9), and the gear disk (8) meshes with the gear on the upper part of the electric / generator (9); an air compressor (6) and a vacuum pump (2) are also provided outside the flywheel chamber (5), the air outlet of the air compressor (6) is at the bottom of the flywheel chamber (5) below the brush seal (14), and the air extraction port of the vacuum pump (2) is at the upper part of the flywheel chamber (5) above the brush seal (14).

2. The distributed magnetic levitation flywheel network energy storage system according to claim 1, wherein It further includes a power electronic control device, a frequency conversion / inversion controller, a power converter, and an auxiliary system.

3. The distributed magnetic levitation flywheel network energy storage system according to claim 2, wherein The power electronic control device includes a microprocessor, a signal acquisition module, and a drive module. The signal acquisition module is used to acquire the operating parameters of the flywheel main structure, and the microprocessor controls the system through the drive module according to the acquired parameters.

4. A distributed magnetic levitation flywheel network energy storage system according to claim 3, characterized in that, The signal acquisition module includes a speed sensor, a current sensor, and a voltage sensor, which are respectively used to acquire the speed of the flywheel (1), the currents of the electromagnetic support device (16), the radial electromagnetic bearing (4), and the axial electromagnetic bearing (11), and the voltage of the electric / generator (9).

5. A distributed magnetic levitation flywheel network energy storage system according to claim 4, wherein The frequency conversion / inversion controller adopts PWM modulation technology and can accurately adjust the voltage, frequency, and phase output by the electric / generator (9).

6. A distributed magnetic levitation flywheel network energy storage system according to claim 5, characterized in that, The power converter is a bidirectional DC-AC converter and can realize bidirectional power conversion between the distributed magnetic levitation flywheel network energy storage system and the power grid.

7. A distributed magnetic levitation flywheel network energy storage system according to claim 6, characterized in that The auxiliary system includes a cooling system and a lubricating system. The cooling system is used to cool the electric / generator (9) and the electromagnetic support device (16), and the lubricating system is used to lubricate the combined bearing (10); the cooling system adopts a water-cooling method and includes a coolant circulation pump, a radiator and cooling pipes, and the coolant cools the electric / generator (9) and the electromagnetic support device (16) through the cooling pipes.

8. A grid connection method for a distributed magnetic levitation flywheel network energy storage system, based on the distributed magnetic levitation flywheel network energy storage system described in claim 1, characterized in that, It includes the following steps: Step 1: System detection and preparation. The state of each flywheel main structure in the distributed magnetic levitation flywheel network energy storage system is detected, including detecting the rotation speed of the flywheel (1), the working states of the electromagnetic support device (16), the radial electromagnetic bearing (4) and the axial electromagnetic bearing (11), and the performance of the electric / generator (9); at the same time, the working states of the power electronic control device, the frequency conversion / inversion controller and the power converter are detected to ensure that the whole system is in a normal operable state; Step 2: Synchronous adjustment. Through the power electronic control device and the frequency conversion / inversion controller, the electric / generators (9) of each flywheel main structure in the distributed network are adjusted to make the voltage, frequency and phase output by each flywheel main structure synchronous with the voltage, frequency and phase of the power grid; Step 3: Grid connection. When the voltage, frequency and phase output by each flywheel main structure are synchronized with the power grid, the distributed magnetic levitation flywheel network energy storage system is connected to the power grid through the power converter to realize the system transmitting electric energy to the power grid or absorbing electric energy from the power grid; Step 4: Operation monitoring and adjustment. During the grid-connected operation, the operation parameters of the distributed magnetic levitation flywheel network energy storage system and the power grid are continuously monitored, including voltage, current and power; according to the monitoring results, the operation states of each flywheel main structure are adjusted in real time through the power electronic control device and the frequency conversion / inversion controller to ensure the stable operation of the system and the power quality, and at the same time, the energy output or input of each flywheel main structure is reasonably allocated according to the demand of the power grid.

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