CN103104417A - Speed-adjustable hub device of large wind turbine generator system - Google Patents

Abstract

The invention provides a speed-adjustable hub device of a large wind turbine generator system. An iron core and a magnet exciting coil are additionally mounted on a hub of a wind turbine. A permanent magnet is additionally mounted on a portion where a rotating shaft acts with the hub. The magnet exciting coil is connected with a sliding ring outside the hub through an electric brush led out from a hub shell. According to the speed-adjustable hub device of the large wind turbine generator system, when the wind speed is over high, wind energy is mainly converted into electric energy, and therefore over high heat is prevented from being generated, and not only can the rotating speed of the wind turbine be lowered, but also redundant wind energy is recycled at the same time. Meanwhile, a wind driven generator is enabled to operate and generate electricity in a rated state even when the wind speed is low. The wind driven generator comprising the speed-adjustable hub device can be directly combined into a power grid, and therefore a high-power converter is eliminated. The speed-adjustable hub device is especially suitable for being used in the large wind turbine generator system.

Description

Adjustable speed hub device for large wind turbines

technical field

The invention relates to a hub device, in particular to a hub device of a large-scale wind power generating set. the

Background technique

For the current wind power generators, due to the unstable wind speed, it is not easy to use the wind speed if the wind speed is too low, and the wind turbine itself is easily damaged if the wind speed is too high. In many cases, no matter how the wind speed changes, the wind turbine requires the speed of the wind turbine to remain constant or not exceed a certain limit range, so a speed regulating or speed limiting device is used. These devices are also used to limit the power and reduce the force acting on the blades when the wind speed is too high. the

At present, there are various types of speed regulating or speed limiting devices, but there are roughly three types in principle: one is to make the wind turbine deviate from the main wind direction, the other is to use aerodynamic resistance, and the third is to change the blade pitch angle. The speed regulation between the wind rotor blades and the wind turbine shaft of traditional wind turbines mainly depends on mechanical speed regulation. The speed of the wind turbine blades is limited by reducing the windward area or through resistance, which only limits the power and wastes energy. And increase the burden on the speed regulating device, affecting its service life and reliability. the

The application number is 201020690123.6, and the patent document entitled "Electromagnetic Brake Device for Wind Power Generator" provides an electromagnetic brake device for wind power generator, including a control system, an electromagnetic block and a magnetic brake part. However, this technical solution only considers limiting the high wind speed. When the wind speed exceeds the wind speed range required by the wind turbine, an electromagnetic brake mechanism is used to realize the deceleration and stop of the rotating shaft through the friction force between the engaging surfaces of the pull-in electromagnetic brake mechanism. The excess wind energy is converted into heat energy after friction, so that the energy is greatly wasted, and the large amount of heat generated has certain requirements and effects on the mechanical structure and material properties, which not only wastes energy, but also reduces the reliability and service life of the equipment. . the

The application number is 201120306693.9, and the patent document titled "An Electromagnetic Brake Device for Wind Power Generator" provides an electromagnetic brake device for wind power generators. It monitors the environment through an anemometer and provides a set of controller solutions. If the wind speed is too high When the coil in the electromagnetic brake device is energized, a magnetic field opposite to the generator stator magnetic field is generated, which hinders the movement of the rotor and achieves the purpose of braking. Not only can't use excess wind energy, but also need to energize the electromagnetic brake device under the condition of excess wind energy to generate reverse magnetic field to achieve the purpose of braking. In addition, due to the electromagnetic coupling effect of the brake device, the excess energy can only be converted into heat energy, and the winding coil will generate a large amount of heat. The coil is easily burned due to excessive temperature, and the reliability and stability are not easy to guarantee. the

Contents of the invention

The purpose of the present invention is to provide a speed-adjustable hub device of a large-scale wind power generating set that can meet the required speed range of the wind power generator and convert excess wind energy into electric energy. the

The purpose of the present invention can be achieved like this:

The first scheme of the present invention is to add iron core and excitation coil on the hub of wind turbine, install permanent magnet additional on the rotating shaft and the hub action part, and the excitation coil is connected with the slip ring outside the hub by drawing out the brush from the hub shell. the

The second solution of the present invention is to install permanent magnets on the hub of the wind turbine, install iron cores and excitation coils on the active parts of the rotating shaft and the hub, and draw brushes from the excitation coil side of the rotating shaft to connect with the slip ring. the

The third scheme of the present invention is to install iron core and excitation coil on the hub of wind turbine, and also install iron core and excitation coil on the part of the rotating shaft and hub, and the hub and rotating shaft lead out the brushes to connect with respective slip rings. the

The slip rings in the above three schemes are connected to the control system through cables, and the control system is connected to the power grid. The speed sensor signal determines whether to feed AC or DC power to the slip ring, or to send power to the power grid through the slip ring. the

The invention provides a hub speed regulating device for maintaining the wind turbine within the rated speed range, and when the wind speed is too high, the excess wind energy is converted into electric energy through electromagnetic induction, and at the same time, the speed of the wind turbine is effectively suppressed. When the wind speed exceeds the rated wind speed, by controlling the energization state of the excitation winding of the hub device, the hub device works in the generator state, and the excess wind energy is converted into electric energy for storage or sent to the grid through power transformation; when the wind turbine does not reach the rated When the speed is high, in order to keep the wind turbine within the rated speed range, by controlling the energization state of the excitation winding of the hub device, the speed regulating device works in the state of the motor, and by compensating the torque between the hub and the rotating shaft, the wind turbine The rotating shaft is always kept within the desired speed range, which can not only meet the speed range required by the wind turbine, but also convert excess wind energy into electrical energy. the

The hub of the wind turbine and the working part of the rotating shaft and the hub are equipped with a core and an excitation coil and a permanent magnet. In this way, energy can be transmitted between the rotating shaft and the hub through electromagnetic coupling. The interaction between the hub and the shaft is through the electromagnetic field between the permanent magnet and the field winding, and the interaction between the hub and the shaft is similar to the stator and rotor of a motor or generator. When the wind speed is too high, the excitation coil is not energized, and the device acts like a generator, reducing the speed and converting excess wind energy into electrical energy. When the speed of the wind turbine is at the rated speed, the excitation coil is fed with direct current, and the hub and the rotating shaft rotate synchronously by electromagnetic attraction. When the wind speed is low, the excitation coil is fed with alternating current, which acts like a motor. Since the three-phase alternating current fed into the coil can be regulated by the control circuit, the synthetic torque can be controlled, so when the wind speed is lower than the rated wind speed, the wind turbine can work at Rated speed, so that the wind turbine can work at the rated state at lower wind speeds. the

The beneficial effect of the present invention is that: the energy generated by the traditional electromagnetic braking device can only be released in the form of heat energy, but the present invention mainly converts the wind energy into electric energy when the wind speed is too high, thus avoiding excessive heat generation, which can reduce the wind turbine speed, while recycling excess wind energy. At the same time, the invention can make the wind power generator still run and generate electricity under the rated state when the wind speed is relatively low. The wind power generator adopting the wheel hub device of the present invention can be directly connected to the power grid, eliminating the need for a high-power converter. the

Description of drawings

Fig. 1 is a block diagram of the application principle of the present invention. the

Fig. 2a-Fig. 2c are principle analysis diagrams of the adjustable speed hub device. Taking the quadrupole permanent magnet on the shaft side as an example, Figure 2a shows that the wind turbine speed is higher than the rated speed; Figure 2b shows that the wind turbine speed is at the rated speed; Figure 2c shows that the wind turbine speed is lower than the rated speed. the

Fig. 3 is an overall structural diagram of the present invention in a wind power generator system. the

Detailed ways

The present invention is described in more detail below in conjunction with accompanying drawing example:

In combination with Fig. 2a-Fig. 2c and Fig. 3, the first scheme of the present invention is: install iron core and excitation winding 2 on the inner side of hub 1 through mechanical fixing, welding and other rigid connection methods, and install There are two bearings 7, silicon steel sheets and permanent magnets 3 are installed on the corresponding rotating shaft 5 part of the wheel hub 1, and the permanent magnets 3 can be inserted. The rotating shaft 5 is the rotating shaft of the generator, and a simple speed-up gearbox can also be added between the generator and the rotating shaft according to the speed requirements of individual generators. The excitation winding 2 is connected with the slip ring 8 outside the hub 1 through the brush 6 drawn out from the hub 1 shell, the nacelle 9 includes the part between the hub 1 and the slip ring 8, and there is a certain air gap between the nacelle 9 and the hub 1, the air gap Keep it as small as possible to prevent dust and debris from entering. The slip ring 8 is connected to the control system 11 through the cable, and the control system 11 is connected to the power grid. The signal of the speed sensor determines whether to supply AC or DC power to the slip ring 8, or to send power to the power grid through the slip ring 8. the

In Figure 2a, T is the total torque of the rotating shaft, T1 is the torque of the wind acting on the hub, T3 is the torque acting on the rotating shaft between the permanent magnet and the excitation winding on the hub, the total torque of the rotating shaft T=T1-T3 . In Figure 2b, T is the total torque of the rotating shaft, T1 wind acts on the torque of the hub, f is the electromagnetic force between the permanent magnet on the rotating shaft and the excitation winding of the hub, and the total torque of the rotating shaft is T=T1. In Figure 2c, T is the total torque of the rotating shaft, T1 is the torque acting on the hub, T2 is the torque acting on the rotating shaft between the permanent magnet and the excitation winding on the hub, and the total torque of the rotating shaft is T=T1+T2. the

Specific working process and principle: When the wind speed is higher than the rated wind speed, the excitation coil is not energized. At this time, since the wind turbine speed is higher than the synchronous speed of the generator, the hub device is running in the generator state, and the excitation winding will cut the magnetic flux generated by the permanent magnet. And generate induced current, which is drawn out through the brush slip ring, and then sent to the power grid or energy storage device after the control conversion circuit. In this way, the excess wind energy is converted into electric energy, and the rotational speed of the rotating shaft is maintained within the rated rotational speed range. Its principle of action is: as shown in Figure 2a, the rotating shaft 5 and the hub 1 have relative motion, so the field winding 2 cuts the magnetic force lines of the permanent magnet 4 to generate an induced current, and at the same time generates a torque that hinders the relative motion of the hub 1 and the rotating shaft 5, and the direction of the torque is It is opposite to the torque that the wind acts on the direction of rotation of the wind turbine. At this time, the excitation winding 2 will generate an induced magnetic field, and act on the permanent magnet 4 through the magnetic field force. The total torque on the rotating shaft 5 is the difference between the torque generated by the wind acting on the hub 1 minus the reverse torque generated by the electromagnetic induction of the excitation winding 2, thereby limiting the further increase of the speed and forcing the speed of the hub 1 to decrease until the wind turbine rated speed. the

When the speed of the wind turbine is lower than the rated speed, the hub device operates in the motor state, and the excitation coil is fed with three-phase alternating current, and the generated rotating magnetic field acts on the permanent magnet to increase the speed of the wind turbine and maintain the speed of the wind generator within the rated speed range Inside. Its principle of action is shown in Figure 2c. Since the current fed into the excitation coil 2 can be controlled, that is, the electromagnetic torque of the hub device can be controlled, so that the rotating shaft 5 integrated with the permanent magnet 4 is subjected to a controllable torque. At this time, the hub 1 It is also subjected to the rotational torque generated by a wind force acting on the blades and the hub. The torque received by the rotating shaft 5 is the sum of the mechanical torque of the wind acting on the hub 1 and the electromagnetic torque generated by the rotating magnetic field after the excitation winding 2 is energized. , so that the speed increases to the rated speed. the

When the speed of the wind turbine is at the rated speed, the control circuit supplies direct current to the excitation device on the hub side, and the suction coupling between the rotating shaft and the hub by the magnetic field transmits the mechanical force of the wind turbine rotation to the rotating shaft and drives the rotating shaft to rotate, so that the rotating shaft Rotate at rated speed. The principle of action is shown in Figure 2b. When the speed of the wind turbine is at the rated speed, the field winding 2 is supplied with direct current. This is equivalent to the fact that there is only a force perpendicular to the tangential direction of the rotating shaft 5 between the field winding and the permanent magnet 4, and there is no rotational torque. At this time The rotational torque that the wind acts on the hub 1 is transmitted to the rotating shaft 5 through electromagnetic coupling, which is basically equivalent to the torque generated by frictional resistance, so the rotating shaft 5 of the wind turbine is basically maintained within the rated speed range. the

The difference between the second scheme of the present invention and the first scheme is that the silicon steel sheet and the permanent magnet are installed on the hub 1, while the iron core and the field winding are assembled on the rotating shaft 5, and the brushes and sliders are drawn from the field winding side of the rotating shaft 5. The slip ring is connected with the control system 11 through cables. The brushes and slip rings on this structure are installed on the rotating shaft, and other structures, working principles and control systems are the same as the first scheme. the

The difference between the third scheme of the present invention and the above two schemes is that both the hub 1 and the rotating shaft 5 are equipped with iron cores and excitation windings, and the hub 1 and the rotating shaft 5 respectively lead out two sets of brushes to connect two sets of slip rings for power supply, and the control system 11 It is necessary to control the power supply of the excitation winding on the rotating shaft and the hub respectively. Embodiment 3 When the speed of the rotating shaft is higher than the rated speed, the electric energy generated by the excitation device on the hub and the rotating shaft is sent to the power grid through the brush and slip ring; when the speed is lower than the rated speed, the excitation device on the rotating shaft needs to obtain electric energy from the power grid. In order to ensure that the excitation winding on the hub emits electric energy at the rated frequency; the speed of the wind turbine is equal to the rated speed, and the two sets of excitation windings should be connected with direct current. The two sets of brushes and slip rings on this structure are respectively installed on the rotating shaft and the wheel hub, and other structures and working principles are the same as the first and second schemes. the

As shown in Figure 1, the design and implementation ideas of the present invention: the iron core, the excitation winding and the wheel hub are connected rigidly in one piece, mechanical fixing, nesting or welding can be considered, and silicon steel sheets are installed on the rotating shaft corresponding to the wheel hub. Permanent magnets are embedded on the chip. The adjustable-speed hub device of the present invention can be directly coaxially connected with the generator, and the adjustable-speed hub device can change the synthesized torque on the rotating shaft side by adjusting the excitation current, and the speed-regulating range is large and easy to realize control, so the low-speed wind-driven generator can be The gearbox is omitted. For a wind turbine with a higher rated speed, it is only necessary to add a small speed-up gearbox between the speed control device and the generator. This allows the electricity generated by the wind turbines to be sent directly to the grid. the

Claims (6)

1. A speed-adjustable hub device for a large-scale wind power generating set, which is characterized in that: an iron core and an excitation coil are installed on the hub of the wind turbine, a permanent magnet is installed on the working part of the rotating shaft and the hub, and the excitation coil is drawn out through the hub shell. The brushes are connected with slip rings on the outside of the hub. 2. The adjustable-speed hub device of a large-scale wind power generating set according to claim 1, characterized in that: the slip ring is connected to the control system through a cable, the control system is connected to the power grid, and the input of alternating current to the slip ring is determined by the speed sensor signal Or direct current, or send power to the grid through slip rings. 3. A speed-adjustable hub device for a large-scale wind power generating set, which is characterized in that: a permanent magnet is added to the hub of the wind turbine, an iron core and an excitation coil are installed on the working part of the rotating shaft and the hub, and the excitation coil is drawn from the side of the rotating shaft The brushes are attached to the slip rings. 4. The speed-adjustable hub device of a large-scale wind power generating set according to claim 3, characterized in that: the slip ring is connected to the control system through a cable, the control system is connected to the power grid, and the input of alternating current to the slip ring is determined by the signal of the speed sensor Or direct current, or send power to the grid through slip rings. 5. A speed-adjustable hub device for a large-scale wind power generating set, which is characterized in that: an iron core and an excitation coil are installed on the hub of the wind turbine, and an iron core and an excitation coil are also installed on the working part of the rotating shaft and the hub, and the hub and the rotating shaft are respectively The outgoing brushes are connected to their respective slip rings. 6. The speed-adjustable hub device of a large-scale wind power generating set according to claim 5, characterized in that: the slip ring is connected to the control system through a cable, the control system is connected to the power grid, and the input of alternating current to the slip ring is determined by the signal of the speed sensor Or direct current, or send power to the grid through slip rings.

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