Method for improving capacity of permanent magnet flywheel energy storage system

Abstract

The invention discloses a method for improving the capacity of a permanent magnet flywheel energy storage system, and the method comprises the steps: enabling the permanent magnet flywheel energy storage system to start grid-connected operation, and determining the rated power of the system; after grid-connected operation, detecting the output power of the permanent magnet flywheel; judging whether the permanent magnet flywheel output power is the system rated power; when the permanent magnet flywheel output power is equal to the system rated power, the super capacitor does not output power, and the detection of the permanent magnet flywheel output power is continued; when the output power of the permanent magnet flywheel is smaller than the rated power of the system, the super capacitor outputs power to supplement the power vacancy of the permanent magnet flywheel, and the capacity of the permanent magnet flywheel energy storage system is improved. The permanent magnet flywheel and the super capacitor share the grid-side converter, the construction cost and the subsequent failure rate are reduced, the output of the super capacitor is used for supplementing the power shortage when the permanent magnet flywheel energy storage system operates in a low rotating speed interval, the capacity of the permanent magnet flywheel energy storage system and the capability of participating in power grid frequency modulation are improved, and the power grid efficiency is improved. The power response capability and stability are enhanced, and the operation performance of the whole power grid system is optimized.

Description

Technical Field

[0001] The present invention relates to a configuration method for a flywheel energy storage system, and particularly to a method for improving the capacity of a permanent magnet flywheel energy storage system under the condition of combined wind and energy storage frequency regulation, belonging to the technical field of permanent magnet synchronous flywheels. Background Art

[0002] With the continuous development of clean energy, as an important part of clean energy, the installed capacity of wind power generation in the power system is increasing rapidly. However, the frequency decoupling phenomenon between wind turbines and the power grid has led to a reduction in system inertia and a decline in stability. This is because most wind turbines use variable pitch or variable frequency speed regulation methods to control the output power and respond to changes in wind speed. Although this method can effectively capture wind energy, it reduces the response ability of the unit to changes in the power grid frequency, thereby affecting the stability of the system.

[0003] Therefore, in order to further improve the support ability of wind turbines for the power grid, an energy storage system is combined with wind turbines to participate in the frequency regulation of the power grid. The permanent magnet flywheel energy storage system is a common form, which uses the high-speed rotational inertia of the permanent magnet flywheel to store energy, but there is also a problem of low energy density. Therefore, it is necessary to study a method for improving the capacity of the permanent magnet flywheel energy storage system. Summary of the Invention

[0004] In order to solve the above technical problems, the main object of the present invention is to propose a method for improving the capacity of a permanent magnet flywheel energy storage system, and the technical solution is as follows:

[0005] A method for improving the capacity of a permanent magnet flywheel energy storage system includes:

[0006] The permanent magnet flywheel energy storage system starts grid-connected operation, and determines the rated power of the system;

[0007] After grid-connected operation, detect the output power of the permanent magnet flywheel;

[0008] Judge whether the output power of the permanent magnet flywheel is the rated power of the system;

[0009] When the output power of the permanent magnet flywheel is equal to the rated power of the system, the super capacitor does not output power, and returns to continue detecting the output power of the permanent magnet flywheel;

[0010] When the output power of the permanent magnet flywheel is less than the rated power of the system, the super capacitor outputs power to supplement the power deficit of the permanent magnet flywheel and improve the capacity of the permanent magnet flywheel energy storage system.

[0011] Further, the output power of the permanent magnet flywheel is P1, and the rated power of the system is P N .

[0012] Further, when the output power of the permanent magnet flywheel is equal to the rated power of the system, the super capacitor does not output power, which means that when the permanent magnet flywheel energy storage system operates in the constant power range with high speed, P1 = P N , and the output power of the super capacitor is P2 = 0;

[0013] Further, when the output power of the permanent magnet flywheel is less than the rated power of the system, the super capacitor outputs power, which means that when the permanent magnet flywheel energy storage system operates in the constant torque range with low speed, P1 < P N , and the output power of the super capacitor is P2 = P N - P1.

[0014] Further, the rated output power of the super capacitor shall not be less than the difference power P between the rated power P of the system and the output power P0 of the permanent magnet flywheel after the super capacitor is connected. The expression of the difference power P is as follows: N P = P

[0015] - P0 N where P0 is the output power of the permanent magnet flywheel, and the expression is as follows:

[0016] In the formula, n1 is the lowest allowable speed of the permanent magnet flywheel before the super capacitor is connected, and n0 is the lowest allowable speed of the permanent magnet flywheel after the super capacitor is connected.

[0017]

[0018] In the formula, n1 is the lowest allowable speed of the permanent magnet flywheel before the super capacitor is connected, and n0 is the lowest allowable speed of the permanent magnet flywheel after the super capacitor is connected.

[0019] Further, the capacity of the permanent magnet flywheel energy storage system is expressed as follows:

[0020]

[0021] In the formula, S2 is the capacity of the permanent magnet flywheel energy storage system after the super capacitor is connected, and S1 is the capacity of the permanent magnet flywheel energy storage system before the super capacitor is connected. The expressions are as follows:

[0022]

[0023] In the formula, n1 is the lowest allowable speed of the permanent magnet flywheel before the super capacitor is connected, and n2 is the highest allowable speed of the permanent magnet flywheel after the super capacitor is connected.

[0024] Further, the permanent magnet flywheel energy storage system includes a doubly-fed wind turbine, a permanent magnet flywheel and a super capacitor. The stator side of the doubly-fed wind turbine is connected to the power grid. The rotor side of the doubly-fed wind turbine and the permanent magnet flywheel are respectively connected to the power grid after passing through the machine side converter and the grid side converter; the permanent magnet flywheel is also connected to the power grid through its machine side converter and grid side converter; the super capacitor adjusts the output voltage to be the same as the DC bus voltage in the permanent magnet flywheel converter through a DC-DC converter and is connected to the DC bus, and then connected to the power grid.

[0025] A device for increasing the capacity of a permanent magnet flywheel energy storage system, comprising:

[0026] A doubly-fed wind turbine module for converting wind energy into electrical energy;

[0027] A permanent magnet flywheel module for converting electrical energy into kinetic energy for storage;

[0028] A machine-side converter module for controlling the variable frequency speed regulation of the motor;

[0029] A grid-side converter module for connecting to the power grid to provide electrical energy output;

[0030] A supercapacitor module for outputting power to supplement the power deficit of the permanent magnet flywheel;

[0031] A converter module for adjusting the output voltage of the supercapacitor to be the same as the DC bus voltage in the permanent magnet flywheel converter.

[0032] A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, the steps of a method for increasing the capacity of a permanent magnet flywheel energy storage system are implemented.

[0033] A storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of a method for increasing the capacity of a permanent magnet flywheel energy storage system.

[0034] Compared with the prior art, its beneficial effects are as follows:

[0035] The permanent magnet flywheel and the supercapacitor share the grid-side converter, reducing the construction cost and subsequent failure rate. By connecting the supercapacitor and using the output of the supercapacitor to supplement the power deficit of the permanent magnet flywheel energy storage system when it operates in the low-speed range, the permanent magnet flywheel energy storage system can operate at the system rated power in a larger range of speed intervals, improving the capacity of the permanent magnet flywheel energy storage system and its ability to participate in power grid frequency regulation, enhancing the power response ability and stability, and optimizing the operation performance of the entire power grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The features and advantages of this patent will be more clearly understood by referring to the accompanying drawings. The drawings are schematic and should not be construed as imposing any limitation on this patent. In the drawings:

[0037] Figure 1 is a schematic diagram of the doubly-fed wind turbine - permanent magnet flywheel - supercapacitor combined system of the present invention;

[0038] Figure 2 is a flowchart of the method for increasing the capacity of the permanent magnet flywheel energy storage system;

[0039] In the figure: 1. Machine-side converter; 2. Grid-side converter; 3. Inner rotor; 4. Outer stator; 5. Flywheel; 6. Blade; 7. DC bus; 8. Doubly-fed converter; 9. Super capacitor; 10. Doubly-fed converter. Detailed implementation manners

[0040] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0041] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0042] Embodiment 1

[0043] As Figure 1 and Figure 2 shown, a method for improving the capacity of a permanent magnet flywheel energy storage system combines a permanent magnet flywheel and a super capacitor. The permanent magnet flywheel outputs power to participate in the frequency modulation of the power grid system mainly, and the super capacitor is used as an auxiliary to improve the performance of the permanent magnet flywheel participating in the frequency modulation of the power grid system. The permanent magnet flywheel energy storage system includes a doubly-fed wind turbine power generation part, a permanent magnet flywheel energy storage part, and a super capacitor energy storage part. The doubly-fed wind turbine is connected to the grid in a conventional manner. The permanent magnet flywheel is connected to the grid through its machine-side converter and grid-side converter. The super capacitor adjusts its output voltage to be the same as the DC bus voltage in the permanent magnet flywheel converter through a DC-DC converter and is connected to the DC bus, and then connected to the grid.

[0044] The doubly-fed wind turbine operates at a certain load reduction rate. When the frequency of the power grid fluctuates, it adjusts its own output power to participate in the frequency modulation of the power grid system. The permanent magnet flywheel and the super capacitor cooperate with each other during operation. When the permanent magnet flywheel operates in the constant power range with a higher rotational speed, the super capacitor does not output power. When the permanent magnet flywheel operates in the constant torque range with a lower rotational speed, the super capacitor adjusts its own output power according to the difference between the output power of the permanent magnet flywheel and the power in the constant power range, so that the permanent magnet flywheel energy storage system can continuously output a constant power. The permanent magnet flywheel energy storage system can operate in a larger range of rotational speed intervals, improving the capacity of the permanent magnet flywheel energy storage system and the supporting ability for the system frequency.

[0045] Embodiment 2

[0046] The permanent magnet flywheel energy storage system can always maintain an output of the rated power P of the system N, assuming that when the supercapacitor is not connected, the minimum allowable rotational speed of the permanent magnet flywheel is n1, corresponding to the intersection of the constant torque region and the constant power region of the permanent magnet flywheel, and the output power is P N , after connecting the supercapacitor, the minimum allowable rotational speed of the permanent magnet flywheel is n0, and the output power at this time is Therefore, the rated output power of the configured supercapacitor shall not be less than P = P N - P0.

[0047] When the permanent magnet flywheel operates in the constant power region, its output power is the system rated power P N , at this time, the supercapacitor does not need to supplement power, and its output power is 0; when the permanent magnet flywheel operates in the lower constant torque region, its output power is less than the system rated power P N , denoted as P1, that is, P1 < P N , at this time, control the supercapacitor output power P2 = P N - P1, so that the overall system output power remains constant.

[0048] The supercapacitor provides power supplement for the permanent magnet flywheel with a lower rotational speed in the constant torque interval, so that its overall output power reaches the system rated power P of the permanent magnet flywheel energy storage system N , so that the permanent magnet flywheel energy storage system can operate in a larger rotational speed range. Assuming that when the supercapacitor is not connected, the allowable rotational speed range of the permanent magnet flywheel is from n1 to n2, and the capacity of the permanent magnet flywheel energy storage system at this time After connecting the supercapacitor, the permanent magnet flywheel energy storage system can operate at a lower rotational speed n0, and the capacity of the permanent magnet flywheel energy storage system at this time Since n0 < n1 and S2 > S1, after connecting the supercapacitor, the capacity of the permanent magnet flywheel energy storage system is improved.

[0049] Embodiment 3

[0050] For this composite energy storage system of the permanent magnet permanent magnet flywheel energy storage system, factors such as the output power of the wind turbine, the change of the grid frequency, and the state of charge (SOC) of the permanent magnet flywheel and the supercapacitor should be comprehensively considered. By precisely controlling the charge and discharge process of the energy storage system, the capacity utilization rate of the permanent magnet flywheel energy storage system under the condition of combined wind and storage frequency modulation can be effectively improved, and the operation performance of the entire power grid system can be optimized.

[0051] Embodiment 4

[0052] The supercapacitor has the advantages of high power density, long cycle life and good temperature characteristics. When used in combination with the permanent magnet flywheel, it can enhance the power response ability and stability while ensuring energy storage.

[0053] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0054] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0055] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific embodiments of the present invention or make equivalent substitutions. Any modification or equivalent substitution that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for increasing the capacity of a permanent magnet flywheel energy storage system, characterized in that Including: The permanent magnet flywheel energy storage system starts grid-connected operation to determine the rated power of the system; After grid-connected operation, detect the output power of the permanent magnet flywheel; Judge whether the output power of the permanent magnet flywheel is the rated power of the system; When the output power of the permanent magnet flywheel is equal to the rated power of the system, the super capacitor does not output power, and return to continue detecting the output power of the permanent magnet flywheel; When the output power of the permanent magnet flywheel is less than the rated power of the system, the super capacitor outputs power to supplement the power shortage of the permanent magnet flywheel and improve the capacity of the permanent magnet flywheel energy storage system.

2. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that The output power of the permanent magnet flywheel is P1, and the rated power of the system is P N .

3. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that, When the output power of the permanent magnet flywheel is equal to the rated power of the system, it means that the supercapacitor does not output power. That is, when the permanent magnet flywheel energy storage system operates in the constant power range with high speed, P1 = P N , and the output power of the supercapacitor is P2 = 0.

4. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that, When the output power of the permanent magnet flywheel is less than the rated power of the system, the output power of the super capacitor means that when the permanent magnet flywheel energy storage system operates in the constant torque range with low speed, P1 < P N , and the output power of the super capacitor is P2 = P N - P1.

5. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that, The rated output power of the super capacitor shall not be less than the system rated power P N The differential power P between the rated output power of the super capacitor and the output power P0 of the permanent magnet flywheel after the super capacitor is connected. The expression of the differential power P is as follows: P = P N -P0 Wherein, P0 is the output power of the permanent magnet flywheel after connecting the super capacitor, and the expression is as follows: Wherein, n1 is the lowest allowable speed of the permanent magnet flywheel before connecting the super capacitor, and n0 is the lowest allowable speed of the permanent magnet flywheel after connecting the super capacitor.

6. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that, The capacity of the permanent magnet flywheel energy storage system is expressed as follows: Wherein, S2 is the capacity of the permanent magnet flywheel energy storage system after connecting the super capacitor, and S1 is the capacity of the permanent magnet flywheel energy storage system before connecting the super capacitor. The expression is as follows: Wherein, n1 is the lowest allowable speed of the permanent magnet flywheel before connecting the super capacitor, and n2 is the highest allowable speed of the permanent magnet flywheel after connecting the super capacitor.

7. A method for increasing the capacity of a permanent magnet flywheel energy storage system according to claim 1, characterized in that, The permanent magnet flywheel energy storage system includes a doubly-fed wind turbine, a permanent magnet flywheel and a super capacitor. The stator side of the doubly-fed wind turbine is connected to the power grid. The rotor side of the doubly-fed wind turbine and the permanent magnet flywheel are respectively connected to the power grid through a machine-side converter and a grid-side converter; the permanent magnet flywheel is also connected to the power grid through its machine-side converter and grid-side converter; the super capacitor adjusts the output voltage to be the same as the DC bus voltage in the permanent magnet flywheel converter through a DC-DC converter, and is connected to the DC bus, and then connected to the power grid.

8. A device for increasing the capacity of a permanent magnet flywheel energy storage system, characterized in that, Including: A doubly-fed wind turbine module for converting wind energy into electrical energy; A permanent magnet flywheel module for converting electrical energy into kinetic energy for storage; A machine-side converter module for controlling the variable frequency speed regulation of the motor; A grid-side converter module for connecting to the power grid to provide electrical energy output; A super capacitor module for outputting power to supplement the power shortage of the permanent magnet flywheel; A converter module for adjusting the output voltage of the super capacitor to be the same as the DC bus voltage in the permanent magnet flywheel converter.

9. A computer device, characterized in that, Including a storage medium, a processor and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of a method for improving the capacity of a permanent magnet flywheel energy storage system according to any one of claims 1-7.

10. A storage medium, characterized in that, The storage medium stores a computer program, and the computer program is executed by the processor to implement the steps of a method for improving the capacity of a permanent magnet flywheel energy storage system according to any one of claims 1-7.

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