Doubly-fed fan-doubly-fed flywheel combined system and method for stabilizing wind power fluctuation

Abstract

The invention discloses a doubly-fed fan-doubly-fed flywheel combined system and method for stabilizing wind power fluctuation, and the system enables the stator sides of a doubly-fed fan and a doubly-fed flywheel to be in grid connection and to be connected with an alternating current bus of the system, and the rotor sides of the doubly-fed fan and the doubly-fed flywheel share the same grid-side converter and then are in grid connection after passing through respective machine-side converters; according to the method, the current value of the doubly-fed flywheel stator is calculated according to the real-time current data of each joint measured by the sensor, and the doubly-fed flywheel machine side converter controls the output of the doubly-fed flywheel stator according to the current value of the doubly-fed flywheel stator. The system is simple in structure, system complexity and control difficulty are reduced, construction cost and later maintenance difficulty are reduced, power fluctuation caused by short-term wind speed change can be effectively stabilized, fluctuation is controlled within a small range, system grid-connected stability and safety are enhanced, system grid-connected point current is made to be constant, and the purpose of stabilizing wind power fluctuation is achieved. And the stability and the safety of the system are improved.

Description

Technical Field

[0001] The present invention relates to a doubly-fed wind turbine system, and particularly to a structure and a control method of a doubly-fed wind turbine-doubly-fed flywheel combined system for suppressing wind power fluctuations, belonging to the technical field of wind power generation. Background Art

[0002] With the development of wind power generation technology, the application of wind power in the power grid system is becoming more and more extensive, and the installed capacity is getting larger and larger. This growth is very beneficial for meeting the growing energy demand and reducing the dependence on fossil fuels. However, the increase in installed capacity also brings a series of challenges to the power grid system. Among them, the volatility of wind speed is the main challenge faced by wind power generation. Since the wind speed is affected by various factors, including geographical location, season, weather conditions, and terrain, etc., it is prone to fluctuations. This kind of fluctuation causes the output power of the wind turbine to change accordingly. When the wind turbine is directly connected to the grid, due to this volatility, a large impact current may be generated at the connection point, which may damage the generator and grid equipment, thus affecting the stable operation of the power grid system and the normal operation of user equipment. It is necessary to connect an energy storage system to suppress the fluctuations of the wind turbine. As a new type of energy storage form, the doubly-fed flywheel energy storage system has the advantages of environmental friendliness, fast response speed, high power, etc., and has great potential in suppressing the fluctuations of the wind turbine. Therefore, a combined system of a doubly-fed wind turbine-doubly-fed flywheel is proposed to better combine the wind turbine and the flywheel, and at the same time, a corresponding control method is proposed to achieve the suppression of the fluctuations of the wind turbine. Summary of the Invention

[0003] In order to solve the above problems, the main object of the present invention is to propose a doubly-fed wind turbine-doubly-fed flywheel combined system and method to suppress wind power fluctuations. The technical solutions are as follows:

[0004] A doubly-fed wind turbine-doubly-fed flywheel combined system for suppressing wind power fluctuations includes a doubly-fed wind turbine and a doubly-fed flywheel. After the stator sides of the doubly-fed wind turbine and the doubly-fed flywheel are connected to the grid, they are connected to the AC bus; the rotor sides of the doubly-fed wind turbine and the doubly-fed flywheel are reconnected to the grid through converters; and a current sensor is also provided in the system.

[0005] Further, the converter includes a machine-side converter and a grid-side converter.

[0006] Further, the rotor sides of the doubly-fed wind turbine and the doubly-fed flywheel are respectively connected to the same DC bus and grid-side converter through their respective machine-side converters and then reconnected to the grid.

[0007] Further, the current sensor is a three-phase current sensor, which is arranged at the connection point of the system, including the stator side of the doubly-fed wind turbine, the stator side of the doubly-fed flywheel, and the grid connection point of the grid-side converter, and is used to detect the real-time current.

[0008] A doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations, comprising:

[0009] Collecting real-time current data of current sensors set in the system;

[0010] Transmitting the collected real-time current data to a controller for calculation to obtain the stator current value of the doubly-fed flywheel;

[0011] Taking the obtained stator current value of the doubly-fed flywheel as a control command and transmitting it to the machine-side converter of the doubly-fed flywheel;

[0012] The machine-side converter of the doubly-fed flywheel controls the stator output of the doubly-fed flywheel according to the stator current value of the doubly-fed flywheel, so that the grid connection point current of the system is constant, achieving the purpose of suppressing wind power fluctuations.

[0013] Further, the current data is the grid connection current I0 of the system, the stator current I1 of the doubly-fed wind turbine, the grid connection current I2 of the grid-side converter, and the stator current I3 of the doubly-fed flywheel.

[0014] Further, in the controller, according to the expression I0 = I1 + I2 + I3, the value of the stator current I3 of the doubly-fed flywheel is calculated.

[0015] A doubly-fed wind turbine-doubly-fed flywheel combined device for suppressing wind power fluctuations, comprising:

[0016] A doubly-fed wind turbine module for converting wind energy into electrical energy;

[0017] A doubly-fed flywheel module for converting electrical energy into kinetic energy for storage;

[0018] A machine-side converter module for controlling the variable frequency speed regulation of the motor;

[0019] A grid-side converter module for accessing the grid to provide electrical energy output;

[0020] A sensor module for detecting real-time current data.

[0021] 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 doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations are implemented.

[0022] A storage medium stores a computer program, and the computer program is executed by a processor according to the steps of a doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations.

[0023] Compared with the prior art, the beneficial effects are as follows:

[0024] Doubly-fed wind turbine - doubly-fed flywheel combined system. According to the structural characteristics of the doubly-fed wind turbine and the doubly-fed flywheel, the two share the same grid-side converter, making the structure more concise, reducing the system complexity and control difficulty, and also reducing the construction cost and the later maintenance difficulty; the method of suppressing wind power fluctuations for the doubly-fed wind turbine - doubly-fed flywheel. According to the real-time current data measured by the sensor at each connection point, the stator current value of the doubly-fed flywheel is calculated. The machine-side converter of the doubly-fed flywheel controls the stator output of the doubly-fed flywheel according to the stator current value of the doubly-fed flywheel, which can effectively suppress the power fluctuations caused by short-term wind speed changes, control the fluctuations within a small range, enhance the stability and security of the system grid connection, make the grid connection point current of the system constant, achieve the purpose of suppressing wind power fluctuations, and improve the stability and security of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The features and advantages of the present invention 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 the present invention. In the drawings:

[0026] Figure 1 It is a schematic diagram of a doubly-fed wind turbine - doubly-fed flywheel combined system for suppressing wind power fluctuations according to the present invention;

[0027] In the figure, 1, machine-side converter; 2, grid-side converter; 3, inner rotor; 4, outer stator; 5, flywheel; 6, blade. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] 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 drawings and specific embodiments. 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.

[0029] 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.

[0030] Embodiment 1

[0031] As Figure 1 shown, the doubly-fed wind turbine - doubly-fed flywheel combined system in the present invention adopts the connection and grid connection method in the figure. The grid connection current I0 of the system, the stator current I1 of the doubly-fed wind turbine, the grid connection current I2 of the grid-side converter, and the stator current I3 of the doubly-fed flywheel are collected through a three-phase current sensor, satisfying I0 = I1 + I2 + I3. When the ambient wind speed increases, the output power of the doubly-fed wind turbine increases, and the stator current I1 and the grid connection current I2 of the grid-side converter increase to I 1(1) and I 2(1), to keep the grid-connected output stable, i.e., to keep the grid-connected current I0 of the system unchanged. Therefore, by adjusting the output of the doubly-fed flywheel, the stator current I of the doubly-fed flywheel is made to 3(1) satisfy I0 = I 1(1) + I 2(1) + I 3(1) That is, I 3(1) = I0 - I 1(1) - I 2(1) .

[0032] Embodiment 2

[0033] As Figure 1 shown, in the combined system of the doubly-fed wind turbine - doubly-fed flywheel in the present invention, the connection and grid connection methods in the figure are adopted. The grid-connected current I0 of the system, the stator current I1 of the doubly-fed wind turbine, the grid-connected current I2 of the grid-side converter, and the stator current I3 of the doubly-fed flywheel are collected through three-phase current sensors, and satisfy I0 = I1 + I2 + I3. When the ambient wind speed decreases, the output power of the doubly-fed wind turbine decreases, and the stator current I1 and the grid-connected current I2 of the grid-side converter decrease to I 1(2) and I 2(2) , to keep the grid-connected output stable, i.e., to keep the grid-connected current I0 of the system unchanged. Therefore, by adjusting the output of the doubly-fed flywheel, the stator current I of the doubly-fed flywheel is made to 3(2) satisfy I0 = I 1(2) + I 2(2) + I 3(2) That is, I 3(2) = I0 - I 1(2) - I 2(2) .

[0034] 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 complete hardware embodiment, a complete 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 storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0035] 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, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be realized 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, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for realizing in the process Figure 1One or more processes and / or boxes Figure 1 Apparatus for the functions specified in one or more boxes

[0036] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction apparatus that implements the functions in the process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes

[0037] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, such that a series of operational steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions in the process Figure 1 One or more processes and / or boxes Figure 1 The steps of the functions specified in one or more boxes

[0038] 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: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A doubly-fed wind turbine-doubly-fed flywheel combined system for suppressing wind power fluctuations, comprising a doubly-fed wind turbine and a doubly-fed flywheel, characterized in that, After the stator sides of the doubly-fed wind turbine and the doubly-fed flywheel are connected to the grid, they are connected to the AC bus; the rotor sides of the doubly-fed wind turbine and the doubly-fed flywheel are re-connected to the grid through converters; the system is also provided with current sensors.

2. The doubly-fed fan-doubly-fed flywheel combined system for suppressing wind power fluctuations according to claim 1, wherein The converter includes a machine-side converter and a grid-side converter.

3. A doubly-fed wind turbine-doubly-fed flywheel combined system for suppressing wind power fluctuations according to claim 2, characterized in that The rotor sides of the doubly-fed wind turbine and the doubly-fed flywheel are respectively connected to the same DC bus and grid-side converter through their respective machine-side converters and then re-connected to the grid.

4. A doubly-fed wind turbine-doubly-fed flywheel combined system for suppressing wind power fluctuations according to claim 1, characterized in that, The current sensor is a three-phase current sensor, which is arranged at the system grid connection point, including the stator side of the doubly-fed wind turbine, the stator side of the doubly-fed flywheel, and the grid connection point of the grid-side converter, and is used to detect the real-time current.

5. A doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations, characterized in that, It includes: Collect the real-time current data of the current sensors set in the system; Transmit the collected real-time current data to the controller for calculation to obtain the stator current value of the doubly-fed flywheel; Transmit the obtained stator current value of the doubly-fed flywheel to the machine-side converter of the doubly-fed flywheel as a control command; The machine-side converter of the doubly-fed flywheel controls the stator output of the doubly-fed flywheel according to the stator current value of the doubly-fed flywheel, so that the current at the system grid connection point is constant, achieving the purpose of suppressing wind power fluctuations.

6. A doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations according to claim 5, characterized in that, The current data are the system grid-connected current I0, the stator current I1 of the doubly-fed wind turbine, the grid-connected current I2 of the grid-side converter, and the stator current I3 of the doubly-fed flywheel.

7. A doubly-fed wind turbine-doubly-fed flywheel method for suppressing wind power fluctuations according to claim 5, characterized in that The calculation in the controller means calculating the value of the stator current I3 of the doubly-fed flywheel according to the expression I0 = I1 + I2 + I3.

8. A doubly-fed wind turbine-doubly-fed flywheel combined device for suppressing wind power fluctuations, characterized in that, It includes: A doubly-fed wind turbine module for converting wind energy into electrical energy; A doubly-fed 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 accessing the grid to provide electrical energy output; A sensor module for detecting real-time current data.

9. A computer device, characterized in that, It includes 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 a doubly-fed wind turbine-doubly-fed flywheel for suppressing wind power fluctuations according to any one of claims 5-7.

10. A storage medium, characterized in that, The storage medium stores a computer program, and the computer program is executed by the processor to perform the steps of a method for a doubly-fed wind turbine-doubly-fed flywheel for suppressing wind power fluctuations according to any one of claims 5-7.

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