High-speed high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection

Abstract

The invention discloses a high-speed high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection, which comprises a high-speed flywheel, a double-rotor brushless motor, a permanent magnet synchronous motor and a controller, and is characterized in that the double-rotor brushless motor comprises a double-rotor brushless motor high-speed rotor, a double-rotor brushless motor low-speed rotor and a double-rotor brushless motor stator winding; wherein a high-speed rotor of the double-rotor brushless motor is connected with the high-speed flywheel, a low-speed rotor of the double-rotor brushless motor is connected with a main shaft of the permanent magnet synchronous motor, and a stator winding of the double-rotor brushless motor is connected with the controller; the controller monitors and controls electrical signals and rotating speed signals of the rotor of the high-speed flywheel, the double-rotor brushless motor and the permanent magnet synchronous motor in real time. According to the technical scheme, the response speed and the transient supporting capacity of an existing flywheel energy storage technology are improved, and on the other hand, the cost of an energy storage system is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to the field of new energy storage equipment, and particularly relates to a high-speed and high-inertia flywheel energy storage system based on grid connection of a permanent magnet synchronous motor. Background Art

[0002] A large number of synchronous generator sets in the new power system are replaced by new energy power generation with a power electronic interface, forming a "dual high" development trend of a high proportion of renewable energy and a high proportion of power electronic devices. The new energy power generation with a power electronic device interface cannot provide frequency support such as mechanical inertia and primary frequency modulation like a synchronous generator set, and has a weak transient overload capacity. Configuring an energy storage device is an effective means to solve the grid connection problem of new energy. As the key to solving the grid connection problem of new energy, new energy storage technologies have developed rapidly in recent years. Among many new energy storage technologies, the flywheel energy storage technology has attracted more and more attention and application in the power system due to its advantages of high frequency, high efficiency, fast response, and large mechanical inertia. At present, the grid connection of a conventional flywheel energy storage system adopts a technical route of "high-speed flywheel + motor + machine-side converter + coupling capacitor + grid-side converter + power grid". This technical solution relies on a back-to-back converter device, and its short-circuit capacity and inertia response characteristics under power system faults are difficult to meet the regulation requirements of the power system. The power electronic converter interface still hinders the inertia response and transient support performance of the conventional flywheel. Summary of the Invention

[0003] To solve the problems of poor transient support ability and slow response speed of the existing flywheel energy storage system, the present invention proposes a high-speed and high-inertia flywheel energy storage system based on grid connection of a permanent magnet synchronous motor. The flywheel energy storage link structure of the present invention is "high-speed flywheel - high-speed rotor of a dual-rotor brushless motor - low-speed rotor of a dual-rotor brushless motor - permanent magnet synchronous motor - power grid". The controller can monitor and control parameters such as the active power, inertia, flywheel speed, dual-rotor brushless motor speed, and synchronous motor speed output by the system, and display the monitoring signals and control actions in real time through an upper computer. When the grid frequency fluctuates, on the one hand, the high-speed flywheel can self-excite and respond to the frequency regulation requirements of the grid, spontaneously decelerate and accelerate through the dual-rotor brushless motor, and at the same time, the controller adjusts the dual-rotor motor, thereby realizing large-range acceleration and deceleration of the flywheel, completing the charge and discharge of the flywheel energy storage system, and participating in the primary frequency modulation of the power grid.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A high-speed and high-inertia flywheel energy storage system based on grid connection of a permanent magnet synchronous motor, comprising a high-speed flywheel, a dual-rotor brushless motor, a permanent magnet synchronous motor, and a controller. The dual-rotor brushless motor includes a high-speed rotor of the dual-rotor brushless motor, a low-speed rotor of the dual-rotor brushless motor, and a stator winding of the dual-rotor brushless motor. The high-speed rotor of the dual-rotor brushless motor is connected to the high-speed flywheel, the low-speed rotor of the dual-rotor brushless motor is connected to the main shaft of the permanent magnet synchronous motor, and the stator winding of the dual-rotor brushless motor is connected to the controller. The controller monitors and controls the electrical signals and speed signals of the rotor of the high-speed flywheel, the dual-rotor brushless motor, and the permanent magnet synchronous motor in real time. When the frequency of the power system fluctuates, the support provided by the high-speed and high-inertia flywheel energy storage system to the power system includes two processes. First, the high-speed flywheel first self-excites through the dual-rotor brushless motor to respond to the frequency regulation needs of the power grid, absorbs and releases active power from and to the power grid through spontaneous acceleration and deceleration, and at the same time provides mechanical inertia. Another process is that while the high-speed flywheel self-excites, the controller adjusts the speed ratio of the dual-rotor brushless motor, so that the high-speed flywheel adjusts its speed in a large speed range and continuously absorbs or releases active power to the power system.

[0006] Beneficial effects:

[0007] The present invention proposes to use a permanent magnet synchronous motor as a grid connection interface. On the one hand, it improves the response speed and transient support ability of the existing flywheel energy storage technology. On the other hand, it effectively reduces the cost of the energy storage system and improves the cycle efficiency. Placing the entire system in a low-pressure or vacuum environment can effectively reduce the loss of the high-speed flywheel, and at the same time solve the problem of dynamic sealing, making the flywheel energy storage system have good primary frequency regulation support ability, and also taking into account the cost and efficiency advantages of the energy storage system. Description of the drawings

[0008] Figure 1 It is a schematic diagram of a high-speed and high-inertia flywheel energy storage system based on grid connection of a permanent magnet synchronous motor of the present invention;

[0009] Among them, 1 - high-speed flywheel; 2 - high-speed rotor of the dual-rotor brushless motor; 3 - low-speed rotor of the dual-rotor brushless motor; 4 - stator winding of the dual-rotor brushless motor; 5 - permanent magnet synchronous motor; 6 - bearing; 7 - support structure; 8 - controller; 9 - power system; 10 - flywheel protection cover; 11 - support base; 12 - vacuum chamber; 13 - power system dispatching instruction; 14 - acquisition and control circuit. Detailed implementation manners

[0010] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0011] Due to the poor transient current overload capacity of power electronic devices, the present invention proposes to use a synchronous motor interface to realize the grid connection of a high-speed flywheel energy storage system, and introduce a dual-rotor brushless motor to realize the differential connection and stepless speed change between the flywheel and the synchronous motor.

[0012] As Figure 1 shown, a high-speed and high-inertia flywheel energy storage system based on the grid connection of a permanent magnet synchronous motor according to the present invention adopts a horizontal structure, and includes a high-speed flywheel 1, a permanent magnet synchronous motor 5, a dual-rotor brushless motor, and a controller 8. The dual-rotor brushless motor includes a dual-rotor brushless motor high-speed rotor 2, a dual-rotor brushless motor low-speed rotor 3, and a dual-rotor brushless motor stator winding 4. The rotor of the high-speed flywheel 1 is connected to the dual-rotor brushless motor high-speed rotor 2, and the permanent magnet synchronous motor 5 is connected to the dual-rotor brushless motor low-speed rotor 3. The dual-rotor brushless motor stator winding 4 is connected to the controller 8. The controller 8 monitors and controls in real time the electrical signals and speed signals of the rotor of the high-speed flywheel 1, the dual-rotor brushless motor, and the permanent magnet synchronous motor 5.

[0013] When the grid frequency fluctuates, the support provided by the flywheel energy storage system to the grid includes two processes. First, the high-speed flywheel 1 first self-excites in response to the frequency regulation needs of the grid, absorbs and releases active power to the grid through spontaneous acceleration and deceleration, and at the same time provides mechanical inertia. Another process is that while the high-speed flywheel 1 self-excites, the controller 8 adjusts the speed ratio of the dual-rotor brushless motor, so that the high-speed flywheel 1 can adjust its speed in a large speed range and continuously absorb or release active power to the grid. Such a new flywheel energy storage system can not only self-excite to provide a transient active power support to the grid, but also the presence of the dual-rotor brushless motor can make this active power support continuous, which is a different system from the existing flywheel energy storage systems.

[0014] In one embodiment, the dual-rotor brushless motor adopts a radial magnetic coupling structure. Except for the stator winding interface of the dual-rotor brushless motor and the grid-connection interface of the permanent magnet synchronous generator in the controller, the entire system is in a low-voltage or vacuum environment. The controller stator winding interface is the interface on the stator winding 4 of the dual-rotor brushless motor for connecting with the controller 8. In the case of being in a vacuum environment, the flywheel energy storage system further includes a vacuum chamber 12. The stator of the permanent magnet synchronous motor 5 and the stator winding 4 of the dual-rotor brushless motor both pass through the reserved leads on the outer shell of the vacuum chamber 12 to penetrate the vacuum and atmospheric environments. The main body of the vacuum chamber 12 is made of materials such as stainless steel, Q235 carbon structural steel, ceramic matrix composite material, quartz glass or borosilicate glass. The controller 8 is in the atmospheric environment, and it is connected to the stator winding 4 of the dual-rotor brushless motor in the vacuum environment through a control line. The chip of the controller 8 adopts DSP or FPGA. The controller 8 monitors and controls the electrical signals and speed signals of the high-speed flywheel 1, the dual-rotor brushless motor and the permanent magnet synchronous motor 5 in real time, and displays the acquisition results and control actions to the host computer in real time; when the frequency of the power system 9 fluctuates, the controller 8 determines the control target of the high-speed flywheel energy storage system based on the power system dispatching instruction 13, and then controls the stator winding 4 of the dual-rotor brushless motor through the acquisition and control circuit 14 to accelerate or decelerate the rotor of the high-speed flywheel 1, complete the charge and discharge of the flywheel energy storage system, so as to respond to the frequency regulation demand of the power system 9. The high-speed and high-inertia flywheel energy storage system may further include a flywheel protection cover 10.

[0015] The high-speed flywheel 1 operates in a high-speed range, so that the flywheel energy storage system has a high moment of inertia and active power reserve, and can support the power system 9 to achieve rapid frequency regulation. In the fault state, the permanent magnet synchronous motor 5 has a strong transient overload capacity and can bear 5 to 7 times the rated overload current in a short time, which can effectively improve the transient response characteristics of the flywheel energy storage system and give full play to the charge and discharge depth of the flywheel energy storage.

[0016] The rotational speed of the high-speed flywheel 1 is much higher than that of the permanent magnet synchronous motor 5. The dual-rotor brushless motor is used to realize the non-contact connection between the high-speed flywheel 1 and the permanent magnet synchronous motor 5 and achieve stepless speed change.

[0017] The inertia response and active power support of the flywheel energy storage system include two methods: transient self-excitation and controller regulation.

[0018] The controller 8 responds in real time to the power system dispatching instructions 13 of the power system 9, and its control objectives are to quickly respond to the inertial support demand, active power support demand, and frequency regulation demand of the power grid system. The controlled parameters of the controller 8 are the rotational speed and acceleration of the high-speed flywheel 1, the rotational speed and acceleration of the dual-rotor brushless motor, the current frequency and amplitude of the stator winding 4 of the dual-rotor brushless motor, the rotational speed of the permanent magnet synchronous motor 5, the grid-connected voltage amplitude and frequency of the permanent magnet synchronous motor 5, and the current of the magnetic levitation bearing; the controller 8 uses the acquisition and control circuit 14 to connect devices such as the high-speed flywheel 1, dual-rotor brushless motor, and permanent magnet synchronous motor 5 of the flywheel energy storage system, and can realize the real-time acquisition and control of the controlled parameters.

[0019] Bearings 6 are installed on the rotating shafts of the rotors of the high-speed flywheel 1, the rotating shafts of the dual-rotor brushless motor, and the main shafts of the permanent magnet synchronous motor 5, and are supported by the support structure 7. The bearing 6 can be a magnetic levitation bearing.

[0020] The flywheel energy storage system further includes a support base 11 for supporting the high-speed flywheel 1, dual-rotor brushless motor, and permanent magnet synchronous motor 5.

[0021] The current of the stator winding 4 of the dual-rotor brushless motor is connected to the converter, and the controller 8 adjusts the amplitude and frequency of the current of the stator winding 4 of the dual-rotor brushless motor; the specific principle of the dual-rotor brushless motor is as follows:

[0022] First, the following definitions are made: the number of pole pairs of the stator magnetic field of the dual-rotor brushless motor, the number of pole pairs of the high-speed rotor of the dual-rotor brushless motor, and the number of magnetic conduction blocks of the low-speed rotor of the dual-rotor brushless motor are , and respectively; the rotational speed of the stator magnetic field, the rotational speed of the high-speed rotor, and the rotational speed of the low-speed rotor are , and respectively, and the current frequency of the stator winding 4 of the dual-rotor brushless motor is . In order to generate a constant torque in the stator air-gap magnetic field, the following relationships are satisfied for the above items:

[0023] ;

[0024] ;

[0025] The number of magnetic conduction blocks of the low-speed rotor 3 of the dual-rotor brushless motor is the sum of the number of pole pairs of the stator magnetic field of the dual-rotor brushless motor and the number of pole pairs of the high-speed rotor 2 of the dual-rotor brushless motor. By changing the current frequency of the stator winding of the dual-rotor brushless motor, the speed difference between the high-speed rotor 2 and the low-speed rotor 3 of the dual-rotor brushless motor can be adjusted, thereby realizing the speed decoupling of the high-speed rotor 2 and the low-speed rotor 3 of the dual-rotor brushless motor.

[0026] During the speed regulation process, the controller 8 decouples the speeds of the high-speed flywheel 1 and the permanent magnet synchronous motor 5. The speed of the low-speed rotor 3 of the dual-rotor brushless motor is synchronized with the power grid frequency, and the high-speed rotor 2 of the dual-rotor brushless motor and the high-speed flywheel 1 are speed-regulated by adjusting the current frequency of the stator winding 4 of the dual-rotor brushless motor.

Claims

1. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection, characterized in that: The flywheel energy storage system comprises a high-speed flywheel (1), a dual-rotor brushless motor, a permanent magnet synchronous motor (5), and a controller (8). The dual-rotor brushless motor comprises a dual-rotor brushless motor high-speed rotor (2), a dual-rotor brushless motor low-speed rotor (3), and a dual-rotor brushless motor stator winding (4), wherein the dual-rotor brushless motor high-speed rotor (2) is connected to the high-speed flywheel (1), the dual-rotor brushless motor low-speed rotor (3) is connected to the main shaft of the permanent magnet synchronous motor (5), and the dual-rotor brushless motor stator winding (4) is connected to the controller (8); the controller (8) monitors and controls the rotor of the high-speed flywheel (1), the dual-rotor brushless motor low-speed rotor (3) in real time, and the stator winding (4) of the dual-rotor brushless motor is connected to the controller (8). The electrical signals and speed signals of the machine and the permanent magnet synchronous motor (5); when the frequency of the power system (9) fluctuates, the support provided by the high-speed and high-inertia flywheel energy storage system to the power system (9) includes two processes. First, the high-speed flywheel (1) first responds to the frequency modulation needs of the power grid through the self-excitation of the dual-rotor brushless motor, absorbs and releases active power to the power grid through spontaneous acceleration and deceleration, and provides mechanical inertia at the same time; the other process is that while the high-speed flywheel (1) self-excites, the controller (8) adjusts the speed ratio of the dual-rotor brushless motor, so that the high-speed flywheel (1) can adjust the speed within a large speed range and continuously absorb or release active power to the power system (9).

2. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 1, characterized in that: The dual-rotor brushless motor structure is a radial magnetic coupling structure.

3. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 1, characterized in that: Except for the controller dual-rotor brushless motor stator winding interface and the permanent magnet synchronous generator grid-connected interface, the entire system is in a low-pressure or vacuum environment.

4. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 3, characterized in that: In a vacuum environment, the high-speed and high-inertia flywheel energy storage system further comprises a vacuum chamber (12), wherein the main body of the vacuum chamber (12) is made of stainless steel, Q235 carbon structural steel, ceramic-based composite material, quartz glass or borosilicate glass.

5. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 1, characterized in that: The high-speed flywheel, the high-speed rotor and the low-speed rotor of the dual-rotor brushless motor are all fixed and supported by magnetic bearings.

6. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 4, characterized in that: The controller (8) is in an atmospheric environment and is connected to a stator winding (4) of a dual-rotor brushless motor in a vacuum environment via a control line.

7. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 6, characterized in that: The controller (8) determines the control target of the high-speed and high-inertia flywheel energy storage system based on the power system dispatch instruction (13), and then controls the stator winding (4) of the dual-rotor brushless motor through the acquisition and control circuit (14) to accelerate or decelerate the rotor of the high-speed flywheel (1), complete the charging and discharging of the flywheel energy storage system, and thus respond to the frequency modulation demand of the power system (9).

8. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 7, characterized in that: The chip of the controller (8) is DSP or FPGA.

9. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 1, characterized in that: The controller (8) collects and controls in real time the speed and acceleration of the high-speed flywheel (1), the speed and acceleration of the dual-rotor brushless motor, the current frequency and amplitude of the stator winding (4) of the dual-rotor brushless motor, the speed of the permanent magnet synchronous motor (5), the grid-connected voltage amplitude and frequency of the permanent magnet synchronous motor (5), and the current of the magnetic bearing.

10. A high-speed and high-inertia flywheel energy storage system based on permanent magnet synchronous motor grid connection according to claim 1, characterized in that: It also includes a supporting base (11) for supporting the high-speed flywheel (1), the dual-rotor brushless motor, and the permanent magnet synchronous motor (5).

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