Wind turbine generator auxiliary braking system suitable for special working conditions and load reduction method

Abstract

The invention discloses a wind turbine generator auxiliary braking system suitable for special working conditions and a load reduction method, the system comprises an electromagnetic brake, an alternating current contactor and a bleeder resistor, the electromagnetic brake comprises a rotor and a stator, the rotor is fixedly connected with a generator rotating shaft and is provided with a permanent magnet, and the stator is provided with a winding coil; the alternating current contactor comprises a normally open contact powered by the unit main control cabinet; the bleeder resistor is respectively connected with the stator winding coil and the alternating current contactor, so that when the unit is powered off, the alternating current contactor is automatically powered off and closed, and the stator winding coil, the alternating current contactor and the bleeder resistor form a closed loop; the alternating current contactor is in signal connection with a unit main control system so as to be closed when receiving a closing control signal of the main control system. The auxiliary braking effect is achieved through the combined design of the electromagnetic brake connected with the rotating shaft of the generator and the electrified normally-open contactor, driving chain damping torque is provided for the unit under the special working condition, and the load of the unit under the special working condition can be reduced.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and more specifically to an auxiliary braking system and load reduction method for wind turbine generators suitable for special operating conditions. Background Technology

[0002] The wind power industry is developing rapidly, with increasing unit capacity, larger wind turbine power and blades, and increasingly heavier loads under certain special operating conditions, such as DLC22b (single-blade jamming), DLC5.1 (emergency stop), and DLC2.3 (grid outage). In DLC5.1 and DLC2.3, the turbine converter typically stops working suddenly, failing to provide torque damping for the wind turbine and making it impossible to reduce these loads through control strategies. The increased loads under these special operating conditions directly lead to increased weight of related components in the turbine design, resulting in a significant increase in cost while complying with IEC or GL design specifications. Therefore, it is necessary to design an effective and economical auxiliary braking system and load reduction method for wind turbines under these special operating conditions. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art by proposing an auxiliary braking system, load reduction method and wind turbine for wind turbines suitable for special working conditions.

[0004] To achieve the above objectives, in a first aspect, the present invention proposes an auxiliary braking system for wind turbines suitable for special operating conditions, comprising an electromagnetic brake, an AC contactor, and a bleeder resistor. The electromagnetic brake includes an electromagnetic brake rotor with a permanent magnet fixedly connected to the generator shaft and an electromagnetic brake stator with a winding coil. The AC contactor includes a normally open contact powered by the main control cabinet of the turbine. The bleeder resistor is connected to the stator winding coil and the AC contactor respectively, so that when the turbine is de-energized, the AC contactor automatically closes, and the stator winding coil, the AC contactor, and the bleeder resistor form a closed circuit. The AC contactor is signal-connected to the main control system of the turbine, so as to close upon receiving a closing control signal from the main control system.

[0005] Furthermore, the two ends of the electromagnetic brake rotor are respectively connected to the generator shaft and the coupling.

[0006] Furthermore, the stator of the electromagnetic brake is fixedly mounted on the generator base.

[0007] Furthermore, the wind turbine auxiliary braking system also includes a flange shaft, which comprises an integrally formed flange and a sleeve portion. The flange is fixedly connected to the electromagnetic brake rotor, and the sleeve portion is fixedly connected to the generator shaft.

[0008] Furthermore, a locking disc is provided on the outer periphery of the sleeve portion, and the sleeve portion is securely connected to the generator shaft by the locking disc.

[0009] Secondly, the present invention provides a wind turbine auxiliary braking load reduction method suitable for special operating conditions, implemented through the aforementioned wind turbine auxiliary braking system, comprising: Under normal operating conditions, the AC contactor is in the energized normally open state, and the permanent magnet rotor of the electromagnetic brake rotates with the generator shaft, generating an induced electromotive force in the stator winding coil. Since the contactor is normally open, no induced current is generated in the coil winding, so no electromagnetic braking damping torque is generated between the stator and rotor of the electromagnetic brake, which does not affect the normal operation of the unit. When an emergency shutdown or power grid outage occurs, the AC contactor closes due to de-energization. The stator winding coil of the electromagnetic brake, the AC contactor, and the discharge resistor form a closed circuit. The stator winding coil generates an induced current under the action of the rotating magnetic field, which creates an electromagnetic torque between the stator and rotor of the electromagnetic brake in the opposite direction to the rotor's rotation. This converts mechanical energy into electrical energy, which is then released as heat through the discharge resistor. The electromagnetic braking torque provides damping torque to the drive chain, suppressing the rapid increase in impeller speed and thus reducing the unit load under this special operating condition.

[0010] Thirdly, the present invention provides a wind turbine auxiliary braking load reduction method suitable for special operating conditions, implemented through the aforementioned wind turbine auxiliary braking system, comprising: Under normal operating conditions, the AC contactor is in the energized normally open state, and the permanent magnet rotor of the electromagnetic brake rotates with the generator shaft, generating an induced electromotive force in the stator winding coil. Since the contactor is normally open, no induced current is generated in the coil winding, so no electromagnetic braking damping torque is generated between the stator and rotor of the electromagnetic brake, which does not affect the normal operation of the unit. When a single blade jamming occurs, the main control system sends a closing signal to the AC contactor, which closes under control. The stator winding coil of the electromagnetic brake, the AC contactor, and the bleeder resistor form a closed circuit. The stator winding coil generates an induced current under the action of the rotating magnetic field, which creates an electromagnetic torque between the stator and rotor of the electromagnetic brake in the opposite direction to the rotor's rotation. This converts mechanical energy into electrical energy, which is then released as heat through the bleeder resistor. The electromagnetic braking torque provides additional damping torque to the drive chain, causing the impeller speed to decrease rapidly, thereby reducing the unit load under this special operating condition.

[0011] Fourthly, the present invention provides a wind turbine generator set including the aforementioned auxiliary braking system.

[0012] This solution combines an electromagnetic brake connected to the generator shaft with a normally open energized contactor. When the contactor is de-energized or receives a signal from the main control system, it closes. The electromagnetic brake rotor rotates with the help of the generator shaft, generating an induced current in the stator winding coils, thus forming an electromagnetic torque opposite to the direction of the generator shaft's rotation, achieving an auxiliary braking function. Furthermore, by reducing the load under special operating conditions, the size and weight of related components can be reduced, thereby lowering the unit cost. Attached Figure Description

[0013] The following figures are included as part of this invention for understanding its principles. The figures illustrate embodiments of the invention and their descriptions, serving to explain the apparatus and principles of the invention. In the figures, Figure 1 This is a schematic diagram showing the location and connection of the wind turbine auxiliary braking system in the turbine unit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the braking principle of the electromagnetic brake according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the connection between the electromagnetic brake and the generator shaft according to an embodiment of the present invention. Detailed Implementation

[0014] The present application will now be described in more detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of the present application more clearly and are not intended to limit the scope of protection of the present application.

[0015] This invention provides an auxiliary braking system and load reduction method for wind turbines suitable for special operating conditions. For example... Figure 1 As shown, the auxiliary braking system of the wind turbine includes an electromagnetic brake 1, an AC contactor 2, and a bleeder resistor 3. The electromagnetic brake 1 includes an electromagnetic brake rotor 11 fixedly connected to the shaft 41 of the generator 4 and an electromagnetic brake stator 12 fixedly mounted on the frame of the generator 4. The AC contactor 2 includes normally open contacts powered by the main control cabinet of the unit. The bleeder resistor 3 is connected to the stator winding coil of the electromagnetic brake 1 and the AC contactor 2 respectively, so that when the unit is de-energized, the AC contactor 2 automatically closes, and the stator winding coil, the AC contactor 2, and the bleeder resistor 3 form a closed circuit. The AC contactor 2 is connected to the main control system of the unit to close when it receives a closing control signal from the main control system.

[0016] like Figure 2As shown, a pair of permanent magnets are installed on the electromagnetic brake rotor 11, forming a rotating permanent magnet magnetic field as the rotor rotates. Stator winding coils are installed on the electromagnetic brake stator 12. When the electromagnetic brake rotor 11 rotates and the stator winding coils are open-circuited, there is only induced electromotive force and no induced current in the stator winding coils. Therefore, no electromagnetic torque can be formed between the stator and rotor, and the rotation of the electromagnetic brake rotor 11 is not affected. When the electromagnetic brake rotor 11 rotates and the stator winding coil circuit is closed, an induced current is generated in the stator winding coils. The current-carrying winding generates an electromagnetic force in the magnetic field, thereby forming an electromagnetic torque between the stator and rotor. The direction of the electromagnetic torque T is opposite to the direction of the rotational speed n of the electromagnetic brake rotor 11, which hinders the rotational motion of the electromagnetic brake rotor 11, thereby achieving the effect of braking damping.

[0017] When the turbine experiences an emergency stop (DLC5.1 condition) or a grid power outage (DLC2.3 condition), the converter suddenly stops working, and the generator torque suddenly becomes zero. The turbine urgently retracts its propellers to reduce the input wind energy torque. However, this retraction requires a time process. Since the generator's drag torque is zero under these two conditions, the rotor will accelerate rapidly during this period, significantly increasing the turbine load. To address these two conditions, the wind turbine auxiliary braking system of this embodiment of the invention performs the following operations: Under normal operating conditions, AC contactor 2 is in a normally open, energized state, and the rotor 11 of electromagnetic brake 1 rotates with the generator shaft 41, generating a rotating magnetic field. When an emergency shutdown condition (DLC5.1) or a power grid outage condition (DLC2.3) occurs, AC contactor 2 de-energizes and closes. The stator winding coil of electromagnetic brake 1, AC contactor 2, and discharge resistor 3 form a closed circuit. The stator winding coil generates an induced current under the influence of the rotating magnetic field, creating an electromagnetic torque between the stator 12 and rotor 11 of electromagnetic brake 1, opposite to the direction of rotor rotation. Mechanical energy is converted into electrical energy, which is then released as heat through the discharge resistor 3 (braking resistor). The electromagnetic braking torque provides a certain damping torque to the drive chain, suppressing the rapid increase in impeller speed and thus reducing the unit load under this special operating condition.

[0018] When a single blade jamming condition (DLC22b condition) occurs, the unit load increases and the rotor load becomes unbalanced. Therefore, it is necessary to take measures to rapidly reduce the rotor speed to lower the unit load under this condition. For this condition, the wind turbine auxiliary braking system of this embodiment of the invention performs the following operations: Under normal operating conditions, AC contactor 2 is in a normally open, energized state, and the rotor 11 of electromagnetic brake 1 rotates with the generator shaft 41, generating a rotating magnetic field. When a single-blade jamming condition (DLC22b condition) occurs, the main control system sends a closing signal to AC contactor 2, which closes under control. The stator winding coil of electromagnetic brake 1, AC contactor 2, and bleeder resistor 3 form a closed circuit. Under the action of the rotating magnetic field, the stator winding coil generates an induced current, creating an electromagnetic torque between the stator 12 and rotor 11 of the electromagnetic brake, opposite to the direction of rotor rotation. Mechanical energy is converted into electrical energy, which is then released as heat through the bleeder resistor 3 (braking resistor). The electromagnetic braking torque provides additional damping torque to the drive chain, causing the impeller speed to decrease rapidly, thereby reducing the unit load under this special operating condition.

[0019] According to embodiments of the present invention, such as Figure 1 and Figure 3 As shown, the two ends of the electromagnetic brake rotor 11 are connected to the generator shaft 41 and the coupling 5, respectively, to transmit the torque of the main drive chain of the unit; the electromagnetic brake stator 12 is fixedly mounted on the generator 4 base. Taking the connection between the electromagnetic brake rotor 11 and the generator shaft 41 as an example, a flange shaft and a locking disc can be used. Specifically, the flange shaft 6 includes an integrally formed flange 61 and a sleeve portion 62. The flange 61 is connected to the electromagnetic brake rotor 11 by bolts 8, and the sleeve portion 62 is fixedly connected to the generator shaft 41. The locking disc 7 is sleeved on the outer circumferential surface of the sleeve portion 62. The locking disc 7 includes two parts that fit with each other at an angle, and the sleeve portion 62 and the generator shaft 41 are tightened together by bolts 9. The end of the electromagnetic brake rotor 11 connected to the coupling 5 is set as a shaft-shaped structure that is fastened to the coupling. The electromagnetic brake rotor 11, while providing auxiliary braking under special working conditions, also serves as a connecting part between the generator and the gearbox to transmit torque.

[0020] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software may depend on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of the embodiments of this disclosure.

[0021] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0022] The methods and products (including but not limited to devices and equipment) disclosed in the embodiments herein can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units may only be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0023] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for descriptive purposes only and is not intended to limit the invention. Terms such as “part” and “component” appearing herein can refer to a single part or a combination of multiple parts. The terms “connection,” “installation,” “linking,” and “setting” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate medium; or a connection within two components. A feature described in one embodiment herein may be applied alone or in combination with other features to another embodiment, unless that feature is not applicable in that other embodiment or is otherwise specified.

[0024] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the present invention to the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An auxiliary braking system for wind turbine generators suitable for special operating conditions, characterized in that, The system includes an electromagnetic brake, an AC contactor, and a bleed resistor. The electromagnetic brake includes an electromagnetic brake rotor with a permanent magnet fixedly connected to the generator shaft and an electromagnetic brake stator with a winding coil. The AC contactor includes normally open contacts powered by the unit's main control cabinet. The bleed resistor is connected to the stator winding coil and the AC contactor respectively, so that when the unit is powered off, the AC contactor automatically de-energizes and closes, and the stator winding coil, the AC contactor, and the bleed resistor form a closed circuit. The AC contactor is connected to the main control system of the unit and closes when it receives a closing control signal from the main control system.

2. The wind turbine auxiliary braking system according to claim 1, characterized in that, The two ends of the electromagnetic brake rotor are connected to the generator shaft and the coupling, respectively.

3. The wind turbine auxiliary braking system according to claim 1, characterized in that, The stator of the electromagnetic brake is fixedly mounted on the generator base.

4. The wind turbine auxiliary braking system according to any one of claims 1-3, characterized in that, The wind turbine auxiliary braking system also includes a flange shaft, which comprises an integrally formed flange and a sleeve. The flange is fixedly connected to the electromagnetic brake rotor, and the sleeve is fixedly connected to the generator shaft.

5. The wind turbine auxiliary braking system according to claim 4, characterized in that, A locking disc is provided on the outer periphery of the sleeve portion, and the sleeve portion is fastened to the generator shaft by means of the locking disc.

6. A wind turbine auxiliary braking load reduction method suitable for special operating conditions, implemented by the wind turbine auxiliary braking system according to any one of claims 1-5, characterized in that, include: Under normal operating conditions, the AC contactor is in the energized normally open state, and the permanent magnet rotor of the electromagnetic brake rotates with the generator shaft, generating an induced electromotive force in the stator winding coil. Since the contactor is normally open, no induced current is generated in the coil winding, so no electromagnetic braking damping torque is generated between the stator and rotor of the electromagnetic brake, which does not affect the normal operation of the unit. When an emergency shutdown or power grid outage occurs, the AC contactor closes due to de-energization. The stator winding coil of the electromagnetic brake, the AC contactor, and the discharge resistor form a closed circuit. The stator winding coil generates an induced current under the action of the rotating magnetic field, which creates an electromagnetic torque between the stator and rotor of the electromagnetic brake in the opposite direction to the rotor's rotation. This converts mechanical energy into electrical energy, which is then released as heat through the discharge resistor. The electromagnetic braking torque provides damping torque to the drive chain, suppressing the rapid increase in impeller speed and thus reducing the unit load under this special operating condition.

7. A wind turbine auxiliary braking load reduction method suitable for special operating conditions, implemented by the wind turbine auxiliary braking system according to any one of claims 1-5, characterized in that, include: Under normal operating conditions, the AC contactor is in the energized normally open state, and the permanent magnet rotor of the electromagnetic brake rotates with the generator shaft, generating an induced electromotive force in the stator winding coil. Since the contactor is normally open, no induced current is generated in the coil winding, so no electromagnetic braking damping torque is generated between the stator and rotor of the electromagnetic brake, which does not affect the normal operation of the unit. When a single blade jamming occurs, the main control system sends a closing signal to the AC contactor, which closes under control. The stator winding coil of the electromagnetic brake, the AC contactor, and the bleeder resistor form a closed circuit. The stator winding coil generates an induced current under the action of the rotating magnetic field, which creates an electromagnetic torque between the stator and rotor of the electromagnetic brake in the opposite direction to the rotor's rotation. This converts mechanical energy into electrical energy, which is then released as heat through the bleeder resistor. The electromagnetic braking torque provides additional damping torque to the drive chain, causing the impeller speed to decrease rapidly, thereby reducing the unit load under this special operating condition.

8. A wind turbine generator set, characterized in that, The wind turbine includes the auxiliary braking system as described in any one of claims 1-5.

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