WO2003016712A1

WO2003016712A1 - Wind power generator

Info

Publication number: WO2003016712A1
Application number: PCT/JP2001/009565
Authority: WO
Inventors: Hareyuki Nishida
Original assignee: Kanki, Kenzou
Priority date: 2001-08-10
Filing date: 2001-10-31
Publication date: 2003-02-27
Also published as: JP2003056446A

Abstract

A wind power generator (11) generating power with wind of relatively low velocity. The wind power generator comprises a power generator (15) including a main generator (16) and an auxiliary generator (17), a main wind mill (22) secured to the forward end of the rotor shaft (18) of the main generator, a sleeve (19) covering the rotor shaft, a radial bearing (26) secured to the sleeve, and an auxiliary wind mill (29) fixed the outer ring part (26a) of the radial bearing. The auxiliary wind mill is disposed proximately to the main wind mill but not touching it. Rotational direction of the auxiliary wind mill is reverse to that of the main wind mill.

Description

Description ^ Technical field

The present invention relates to a wind power generator. Background art

The wind turbine of a conventional wind turbine starts rotating when it receives winds at a predetermined start wind speed (cut-in wind speed) or higher. The wind turbine that has started to rotate continues to rotate even if the wind speed falls below the cut-in wind speed. In order to improve the power generation efficiency of a wind turbine, a wind turbine that starts with relatively low speed wind is required.

2. Description of the Related Art Conventionally, a wind power generation device that controls a mounting angle (pitch angle) of a blade of a wind turbine to generate power using relatively low-speed wind has been known. However, a wind power generator that performs pitch control requires a complicated pitch control mechanism. In addition, when the wind turbine is large, there is a problem that it takes time to control the pitch. Disclosure of the invention

An object of the present invention is to provide a wind power generator having a relatively simple structure and improved power generation efficiency.

In order to achieve the above object, according to one aspect of the present invention, there is provided a wind power generator including a main wind turbine driving a generator, and an auxiliary wind turbine arranged coaxially with the main wind turbine and rotated independently of the main wind turbine. Provided. The starting wind speed of the auxiliary wind turbine is lower than the starting wind speed of the main wind turbine. The auxiliary wind turbine is located close to the main wind turbine so that when the auxiliary wind turbine is rotated, the main wind turbine is started at a lower speed than the main wind turbine. According to another aspect of the present invention, there is provided a wind power generator including a main wind turbine driving a generator, and an auxiliary wind turbine arranged coaxially with the main wind turbine and rotated in the same direction as the main wind turbine. The starting wind speed of the auxiliary wind turbine is lower than the starting wind speed of the main wind turbine. The wind turbine transmits the rotation of the auxiliary wind turbine to the main wind turbine, starts the main wind turbine, and releases the transmission of the rotation from the auxiliary wind turbine to the main wind turbine after the main wind turbine starts rotating. And a transmission switching device for removing.

When receiving wind, the auxiliary wind turbine and the main wind turbine preferably rotate in opposite directions. Preferably, the wind power generator further comprises a frame rotatably supporting the main wind turbine, and a bearing mounted on the frame and rotatably supporting the auxiliary wind turbine. The frame preferably includes a sleeve covering the rotor shaft of the generator connected to the main wind turbine, and the bearing is preferably fixed to the outer surface of the sleep. It is preferable that the auxiliary wind turbine is located downstream of the main wind turbine. The wind power generator may further include an auxiliary generator driven by the auxiliary wind turbine to generate power, and a connection switching device for connecting the auxiliary wind turbine to the auxiliary generator when the rotation speed of the main wind turbine is equal to or higher than a predetermined value. It is good. The main wind turbine has a plurality of main blades, the auxiliary wind turbine has at least one auxiliary blade, and the number of the auxiliary blades is preferably smaller than the number of the main blades. The auxiliary wind turbine is preferably stopped or decelerated when the rotation speed of the main wind turbine reaches a predetermined value or more. It is preferable that the wind power generator further includes a sensor that detects the rotation speed of the main wind turbine. The connection switching device preferably includes an electromagnetic clutch that switches the connection between the auxiliary wind turbine and the auxiliary generator based on a signal from the sensor. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view of a power generator according to one embodiment of the present invention.

FIG. 2 is a perspective view of the wind turbine generator of FIG.

Figure 3 is an enlarged view of the mounting part between the blade and the hub.

Figure 4 is a schematic diagram of the experimental device.

Figure 5 is a graph showing the experimental results.

FIG. 6 is a partial cross-sectional view of a power generator according to another embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a wind power generator 11 according to an embodiment of the present invention will be described.

As shown in FIG. 2, the wind turbine generator 11 has a fixed portion 12 fixed to the ground and a fixed portion 12 fixed to the ground. A hollow metal strut 13 extending substantially perpendicularly from the fixed portion 12. A support case 14 rotatable around the column 13 is arranged at the upper end of the column 13. A tail fin 14 a is fixed to the support case 14. When the tail fin 14 a receives wind, the support case 14 is rotated so that the tail fin 14 a faces leeward. At the upper part of the support case 14, a power generator 15 is attached.

The power generator 15 will be described with reference to FIG.

The generator 15 includes a main generator 16, an auxiliary generator 17, and a casing 15 a that houses the generators 16 and 17. The main generator 16 is connected to a rotor shaft 18 arranged substantially horizontally. The rotor shaft 18 penetrates a sleeve 19 fixed to the casing 15a, and protrudes outside the casing 15a. A disc-shaped main hub 20 is fixed to the tip of the rotor shaft 18. The rotor shaft 18 rotates together with the main hap 20. In one embodiment, the frame is formed by the casing 15 a and the sleeve 19.

Three main blades 21 extending radially are attached to the main hub 20 at equal angular intervals (120 °). The main wind turbine 22 is formed by the main hub 20 and the main blade 21.

At a predetermined position on the peripheral surface of the sleeve 19, a radial bearing 26 is attached. An annular auxiliary hub 27 having the same diameter as the main hub 20 is fixed to the outer ring portion 26 a of the radial bearing 26. Two auxiliary blades 28 having the same dimensions as the main blade 21 and extending radially are attached to the auxiliary haptic 27 at equal angular intervals (180 °). An auxiliary hub 27 and an auxiliary blade 28 form a catch wind turbine 29.

The main windmill 22 and the auxiliary windmill 29 are coaxial and are independently rotated. The main wind turbine 22 and the auxiliary wind turbine 29 are arranged relatively close to each other, and the interval between the two wind turbines 22 and 29 is set to a value that does not contact each other during rotation.

A bevel gear 31 is attached to the rear surface of the outer ring 26 a of the radial bearing 26. The bevel gear 31 is engaged with a gear mechanism 32 attached to the casing 15a. The gear mechanism 3 2 is connected to the auxiliary generator 1 7 via the electromagnetic clutch 3 3. Drive shaft 17a. The electromagnetic clutch 33 selectively connects the drive shaft 17 a and the gear mechanism 32 to selectively transmit the rotational energy of the auxiliary wind turbine 29 to the auxiliary generator 17. The electromagnetic clutch 33 is activated according to a signal from a sensor 33a that detects the rotation speed of the rotor shaft 18. Specifically, the electromagnetic clutch 33 connects the gear mechanism 32 to the drive shaft 17a when the rotation speed of the rotor shaft 18 exceeds a predetermined value. On the other hand, when the rotation speed of the rotor shaft 18 is equal to or lower than a predetermined value (for example, during stoppage), the gear mechanism 32 and the drive shaft 17a are disconnected. The electromagnetic clutch 33 and the sensor 33a form a connection switching device.

The connection between the blades 21 and 28 and the hubs 20 and 27 will be described with reference to FIGS.

The main blade 21 and the auxiliary blade 28 are attached to the main hub 20 and the f-auxiliary hub 27 by two L-shaped metal plate connectors 35a and 35b, respectively. Specifically, the blade connector 35 a is screwed to each blade 21, 28, and the hub connector 35 b is screwed to the main hub 20 or the auxiliary hub 27. The blade connector 35a and the associated hub connector 35b are connected to each other by bolts 36a and nuts 36b. By loosening the bolt 36a, the mounting angle (pitch angle) α of each blade 21 and 28 can be adjusted.

As shown in FIG. 3, the blade connector 35 a is fixed at the base end of the main blade 21 so as to be shifted to the one edge 21 a side. The pitch angle α is set such that the distance between the other edge 21b of the main blade 21 and the main hub 20 is larger than the distance between one edge 21a and the main hub 20. Further, the blade connector 35 a is fixed at the base end of the catching blade 28 so as to be shifted to the one edge 28 a side. The pitch angle is set so that the distance between the other edge 28 b of the auxiliary blade 28 and the catching hub 27 is larger than the distance between one edge 28 a and the auxiliary hub 27. The direction of inclination of the main blade 21 is opposite to the direction of inclination of the auxiliary blade 28. Therefore, the auxiliary wind turbine 29 rotates in the opposite direction to the main wind turbine 22. Specifically, in FIG. 2, the main wind turbine 22 rotates counterclockwise, and the auxiliary wind turbine 29 rotates clockwise. To rotate. When the pitch angle is set so that the direction of the inclination of the auxiliary blade 28 is the same as the direction of the inclination of the main blade 21 as shown by the dashed line in FIG. 3, the auxiliary wind turbine 29 becomes the main wind turbine. Windmill 2 Turns in the same direction as 2 (counterclockwise). Next, the operation of the wind turbine generator 11 according to one embodiment will be described.

When the wind blows, the tail fins 14 a receive the wind and the support case 14 rotates. Then, the support case 14 stops at the position where the wind resistance received by the tail fins 14a becomes the smallest. In other words, the tip of the tail fin 14 a faces leeward, and the main windmill 22 faces leeward. In this way, the main windmill 22 is always directed to the windward direction by the tail fins 14a.

When the wind speed is relatively low and both the main windmill 22 and the auxiliary windmill 29 are stopped, the electromagnetic clutch 33 disconnects the auxiliary windmill 29 from the auxiliary generator 17.

As the wind speed increases, first, the auxiliary wind turbine 29 starts to rotate. This is for the following reasons. The number of blades of the auxiliary wind turbine 29 is two, which is less than the number of blades (three) of the main wind turbine 22. Further, a load based on the connection with the main generator 16 acts on the main wind turbine 22. On the other hand, the auxiliary wind turbine 29 is separated from the auxiliary generator 17 by the electromagnetic clutch 33. Therefore, the auxiliary wind turbine 29 is started by a lower speed wind than the main wind turbine 22.

The main windmill 22 is activated under the influence of the rotation of the auxiliary windmill 29. That is, the main wind turbine 22 is started by a wind lower in speed than the starting wind speed of the main wind turbine 22 alone.

When the rotation speed of the main wind turbine 22 and the rotor shaft 18 becomes higher than the predetermined speed, the electromagnetic clutch 33 connects the auxiliary wind turbine 29 and the auxiliary generator 17 and the gear mechanism 32 drives the driving shaft. Linked to 17 a. As a result, the rotational energy of the auxiliary wind turbine 29 is transmitted to the auxiliary generator 17, and the auxiliary generator 17 generates electricity.

When the wind speed decreases and the rotation speeds of the main windmill 22 and the rotor shaft 18 become lower than a predetermined speed, the electromagnetic clutch 33 disconnects the auxiliary windmill 29 from the auxiliary generator 17. Thereby, the load acting on the auxiliary wind turbine 29 is reduced, and the rotation speed of the auxiliary wind turbine 29 is increased. Due to the effect of the increase in the rotation speed of the auxiliary wind turbine 29, the rotation speed of the main wind turbine 22 increases. Therefore, the amount of power generated by the main generator 16 is secured.

Next, characteristics of the wind turbine generator 11 according to the embodiment will be described. The characteristics were tested using the experimental device shown in Fig. 4.

As shown in FIG. 4, a wind tunnel device 51 is installed in front of the wind power generation device 11. The wind tunnel device 51 includes a cylindrical wind tunnel 52 having a blower 53 and a current plate 55. The number of rotations per second (rotational speed) of the blower 53 can be changed in synchronization with the frequency of the drive current. The rotation speed of the blower 53 was changed by changing the frequency of the drive current by the power supply 54 provided with an inverter. A voltmeter 56 is connected to the wind power generator 11 so that the generated voltage of the main generator 16 can be observed. Note that the electromagnetic clutch 33 is maintained in a disconnected state.

The distance from the air outlet of the wind tunnel 52 to the main wind turbine 22 is 150 cm, and the pitch angle α of the main wind turbine 22 is 15. It is. The distance between the main wind turbine 22 and the auxiliary wind turbine 29 is 2.5 cm. For the blades 21 and 28, cut a rectangular plate with a length of 20 cm and a width of 4 cm, and cut it diagonally from 2 cm from the base end so that the width of the tip becomes 1.7 cm. A pentagonal plate was used.

Hereinafter, characteristic experiments 1 to 5 will be described. When the pitch angle of the auxiliary wind turbine 29 is set to rotate in the same direction as the main wind turbine 22, the pitch angle a of the auxiliary wind turbine 29 is indicated by a positive value, and the auxiliary wind turbine 29 is rotated in the opposite direction. If it is set, the pitch angle α is indicated by a negative value.

Experiments 1 to 6 were performed under the following conditions. In Experiment 1, the auxiliary wind turbine was omitted.

In Experiment 2, the pitch angle of the auxiliary wind turbine was 130 °.

In Experiment 3, the pitch angle α of the auxiliary wind turbine was 120 °.

In Experiment 4, the pitch angle of the auxiliary wind turbine was 110 °.

In Experiment 5, the pitch angle of the auxiliary wind turbine is + 10 °.

In each of the experiments 1 to 5, the frequency of the power supply 54 (power supply frequency) was increased by 1 Hz from the 15 Hz power, and the wind speed of the blower 53 was increased. The dynamic wind speed (power-in wind speed) was examined. After the main wind turbine 22 was started, the frequency of the power supply unit 54 was decreased by 1 Hz, and the generated voltage (V) of the main generator 16 at each wind speed was measured by the voltmeter 56.

Experiments 2 to 4 were repeated several times. Table 1 shows the results of the repeated experiments, and Figure 5 shows one result.

As shown in Table 1 and FIG. 5, when there was no auxiliary wind turbine 29 (Experiment 1), the main wind turbine 22 started to rotate at the starting wind speed corresponding to the power frequency of 31 Hz. In Experiments 2, 3, 4, and 5, the main windmill 22 began to rotate at 28 Hz, 26 Hz, 26 Hz, and 27 Hz, respectively. From this, it was found that the auxiliary wind turbine 29 reduces the starting wind speed of the main wind turbine 22. That is, it was found that the wind power generator 11 having the auxiliary wind turbine 29 can generate power with a relatively low speed wind.

From the results of Experiments 2 to 4, it was observed that the smaller the absolute value of the pitch angle a of the auxiliary wind turbine 29, the higher the rotation speed of the auxiliary wind turbine 29. When the pitch angle α of the auxiliary wind turbine 29 was larger than a predetermined value (Experiment 4), it was found that the voltage generated by the main generator 16 was reduced. · According to another experimental result (not shown), when the auxiliary wind turbine 29 rotates in the opposite direction to the main wind turbine 22, compared to when both the wind turbines 22 and 29 rotate in the same direction, the main generator It was found that the generation voltage of 16 was slightly higher.

Further, the same experiment was performed when the distance between the main wind turbine 22 and the auxiliary wind turbine 29 was changed to 3.0 cm and 3.5 cm. From the result, it became clear that the shorter the distance between the main wind turbine 22 and the auxiliary wind turbine 29 is, the more the main wind turbine 22 is started at a lower wind speed.

In the experimental results when the intervals are 3.0 cm and 3.5 cm, it is better to reduce the absolute value of the pitch angle a and make the rotation speed of the auxiliary wind turbine 29 higher, so that the main It was confirmed that windmill 22 was started. It can be seen that the main windmill 22 is started with a lower speed than when the auxiliary windmill 29 is rotated in the opposite direction to the main windmill 22 in the same direction as the main windmill 22. Was. Note that the adoption of the catch wind turbine 29 causes the startup wind speed of the main wind turbine 22 to be lower than the startup wind speed in the stand-alone state because the wind is drawn by the rotation of the auxiliary wind turbine 29 and the wind to the main wind turbine 22 It is considered that the input angle changes. For this reason, when the absolute value of the pitch angle of the auxiliary wind turbine 29 is small, the rotation speed of the auxiliary wind turbine 29 becomes higher, so that the input angle of the wind changes greatly, and the main wind turbine 2 2 is activated.

When the rotation direction of the auxiliary wind turbine 29 is opposite to that of the main wind turbine 22, the auxiliary wind turbine 29 is rotated at a higher speed. This is presumably because the wind affected by the rotation of the main wind turbine 22 is incident on the auxiliary wind turbine 29 at an angle at which the auxiliary wind turbine 29 can be more easily rotated.

In Experiment 4 in which the pitch angle α of the blades of the auxiliary wind turbine 29 is −10 °, the power generation efficiency of the main generator 16 is reduced. This is thought to be because the auxiliary wind turbine rotating at a predetermined speed or more acts as a wall that hinders the flow of wind. The output reduction of the main generator 16 is prevented by the electromagnetic clutch 33 connecting the auxiliary wind turbine 29 and the auxiliary generator 17 to apply a load to the auxiliary wind turbine 29.

According to the embodiment, the following effects can be obtained. (1) The wind turbine 11 has an auxiliary wind turbine that is slower than the starting wind speed of the main wind turbine 2 2.

2 9 are located close to the main windmill 22. With such a relatively simple structure, the main wind turbine 22 is started by a wind having a lower speed than the starting wind speed of the main wind turbine 22 alone, and the power generation efficiency of the main generator 16 is improved. The rotation direction of the auxiliary wind turbine 29 may be set to the same direction as the rotation direction of the main wind turbine 22 or to the opposite direction.

(2) When the auxiliary wind turbine 29 is rotated in the opposite direction to the main wind turbine 22, the main wind turbine 22 is started by a lower speed wind, and the main generator 16 and the auxiliary generator 17 are connected to each other. The combined power generation efficiency is improved.

(3) The auxiliary wind turbine 29 is supported by a sleeve 19 that supports the main wind turbine 22 via a radial bearing 26. Therefore, the main windmill 22 and the auxiliary windmill 29 rotate independently of each other with a relatively simple structure. Since the auxiliary wind turbine 29 is supported by the sleeve 19, the rotor shaft 18 does not receive the load of the auxiliary wind turbine 29. Therefore, the main wind turbine 22 is rotated with a relatively small resistance and resistance, and the power generation efficiency of the wind power generator 11 is improved.

(4) The auxiliary windmill 29 is located downstream of the main windmill 22. Therefore, the main wind turbine 22 receives the wind before the auxiliary wind turbine 29, and the power generation efficiency of the wind power generator 11 can be further improved.

(5) When the rotation speed of the main wind turbine 22 exceeds a predetermined speed, the electromagnetic clutch

3 3 connects the auxiliary wind turbine 29 with the auxiliary generator 17. Therefore, the rotational energy of the auxiliary wind turbine 29 can also be used for power generation, and the power generation efficiency of the wind power generator 11 is improved. In addition, the connection of the auxiliary wind turbine 29 and the auxiliary generator 17 increases the rotational resistance of the auxiliary wind turbine 29. As a result, the rotation speed of the auxiliary wind turbine 29 is restricted to be equal to or higher than the predetermined speed, and a decrease in the power generation efficiency of the main wind turbine 22 is prevented.

(6) The number of auxiliary blades 28 (two) is smaller than the number of main blades 21 (three). In this way, the starting wind speed of the auxiliary wind turbine 29 can be made lower than the starting wind speed of the main wind turbine 22 relatively easily at a relatively low cost. Since the number of auxiliary blades 28 is different from the number of main blades 21, all auxiliary blades 28 The overlap with the in-plane 21 is prevented. As a result, the auxiliary wind turbine 29 can receive sufficient wind.

(7) By reducing the distance between the auxiliary wind turbine 29 and the main wind turbine 22, the starting wind speed of the main wind turbine 22 is reduced.

(8) By reducing the absolute value of the pitch angle α of the blades of the auxiliary wind turbine 29 and increasing the rotation speed of the auxiliary wind turbine 29, the effect of the main wind turbine 22 on the auxiliary wind turbine 29 can be increased. it can. As a result, the main wind turbine 22 is started at a lower wind speed.

The above embodiment may be modified as follows.

• The main wind turbine 22 and the auxiliary wind turbine 29 are not limited to being rotatably supported independently of each other. For example, as shown in FIG. 6, a disk 71 having a diameter substantially equal to the diameter of the auxiliary hub 27 is formed integrally with the rotor shaft 18. An electromagnet 72 is attached to the casing 15a via a bracket 15b. The electromagnet 72 is disposed to face the auxiliary hub 27 and is excited when the rotation speed of the rotor shaft 18 is equal to or higher than a predetermined value. Between the electromagnet 72 and the auxiliary hub 27, a leaf spring (not shown) for urging the auxiliary hub 27 toward the disk 71 is arranged. The auxiliary hub 27 is supported by a radial bearing 26 so as to be slightly slidable along the axis of the rotor shaft 18. The transmission switching device is formed by the auxiliary hub 27, the disk 71, and the electromagnet 72. The pitch angle is set to gx / E 0 so that the auxiliary wind turbine 29 rotates in the same direction as the main wind turbine 22.

When both the main windmill 22 and the auxiliary windmill 29 are stopped, the electromagnetic clutch 33 disconnects the auxiliary windmill 29 from the auxiliary generator 17, and the electromagnet 72 is demagnetized. ing. Therefore, the auxiliary hub 27 is in contact with the disc 71 by the urging force of the leaf spring, and is rotatable relative to the disc 71.

As the wind speed increases, the auxiliary wind turbine 29 starts to rotate. The rotation of the auxiliary wind turbine 29 is transmitted to the rotor shaft 18 by friction between the auxiliary hub 27 and the disk 71, and the main wind turbine 22 starts rotating. That is, the main windmill 22 is started by the wind having a speed lower than the wind speed of the main windmill 22 alone. When the rotation speeds of the main windmill 22 and the rotor shaft 18 reach predetermined values, the electromagnets 72 are excited. As a result, the auxiliary hub 27 is attracted to the electromagnet 72, the contact between the auxiliary hub 27 and the disk 71 is released, and the connection between the main wind turbine 22 and the auxiliary wind turbine 29 is released. Thereby, the main windmill 22 rotates efficiently. The auxiliary wind turbine 29 is connected to the auxiliary generator 17 by the electromagnetic clutch 33 after the contact with the disk 71 is released. As a result, the auxiliary generator 17 generates electric power using the rotational energy of the auxiliary wind turbine 29.

Therefore, even in this case, when the main windmill 22 is stopped and the auxiliary windmill 29 is started by the wind having a lower speed than the starting wind speed of the main windmill 22, the main windmill 22 is rotated by the rotation of the auxiliary windmill 29. Can start. It is preferable to set the blade pitch of the auxiliary wind turbine 29 to about + 30 ° in order to rotate the auxiliary wind turbine 29 under load in contact with the disk 71. .

• The number of blades of the main wind turbine 22 may be changed. Further, the number of the assisting blades 28 may be changed, but is preferably smaller than the number of the main blades 21.

• The number of auxiliary blades 28 does not have to be set smaller than the number of main blades 21. If the starting wind speed of the auxiliary wind turbine 29 is lower than the starting wind speed of the main wind turbine 22, the number of the auxiliary blades 28 may be equal to or larger than the number of the main blades 21.

'The size of the auxiliary blade 28 may be different from that of the main blade 21. The auxiliary blade 28 may be larger than the main blade 21, but is preferably equal to or smaller than the main blade 21.

• The auxiliary generator 17, bevel gear 31, gear mechanism 32, and electromagnetic clutch 33 need not be attached to the generator 15.

• The brake mechanism may be operated to decelerate or stop the auxiliary wind turbine 29 so that the rotation speed of the main wind turbine 22 does not exceed a predetermined value. Even in this case, it is possible to prevent the auxiliary wind turbine 29 from reducing the power generation efficiency of the main wind turbine 22.

• Instead of being fixed to the casing 15a, the sleeve 19 may be supported by a support member extending from the upper surface of the support case 14, for example. Even in this case, since the load of the auxiliary wind turbine 29 does not act on the main wind turbine 22, it is difficult to rotate the main wind turbine 22. I can do it. Note that the support member and the sleep 19 function as a frame.

• The sleeve 19 may be attached to the main generator 16 instead of being fixed to the casing 15a. Even in this case, since the load of the catch wind turbine 29 does not act on the main wind turbine 22, the main wind turbine 22 can be easily rotated. Sleep 19 functions as a frame.

• A thrust bearing may be used instead of the radial bearing 26 supporting the auxiliary wind turbine 29.

• Instead of the flat blades 21 and 28, twisted blades may be used.

The auxiliary wind turbine 29 may be arranged on the windward side of the main wind turbine 22. Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, the wind power generator which has a comparatively simple structure and starts with a comparatively low speed wind, and which improved power generation efficiency is provided.

Claims

The scope of the claims

1. The main windmill (22) driving the generator (16),

A wind turbine generator (11) comprising: an auxiliary wind turbine (29) arranged coaxially with the main wind turbine and rotated independently of the main wind turbine;

The starting wind speed of the auxiliary wind turbine is lower than the starting wind speed of the main wind turbine; and Is disposed close to the main wind turbine.

2. The wind power generator according to claim 1, wherein when receiving wind, the auxiliary wind turbine and the main wind turbine rotate in opposite directions.

3. Frames (15a, 19) for rotatably supporting the main windmill,

The wind power generator according to claim 1 or 2, further comprising: a bearing (26) mounted on the frame and rotatably supporting the auxiliary wind turbine.

4. The frame includes a sleeve (19) covering a rotor shaft (18) of the generator connected to the main wind turbine, wherein the bearing is fixed to an outer surface of the sleeve. Item 4. The wind turbine generator according to item 3.

5. The wind power generator according to any one of claims 1 to 4, wherein the auxiliary wind turbine is arranged downstream of the main wind turbine.

6. The wind power generator further comprises:

An auxiliary generator (17) driven by the auxiliary windmill to generate power,

6. A connection switching device (33) for connecting the auxiliary wind turbine to the auxiliary generator when the rotation speed of the main wind turbine is equal to or higher than a predetermined value. The wind power generator according to any one of the above.

7. The main wind turbine has a plurality of main blades, the auxiliary wind turbine has at least one auxiliary blade, and the number of the auxiliary blades is smaller than the number of the main blades. The wind power generator according to any one of the above 6

8. The wind turbine according to any one of claims 1 to 7, wherein the auxiliary wind turbine is stopped or decelerated when the rotation speed of the main wind turbine reaches a predetermined value or more.

9. The main windmill (22) driving the generator (16),

A wind turbine generator (11) comprising: an auxiliary wind turbine (29) arranged coaxially with the main wind turbine and rotated in the same direction as the main wind turbine,

The starting wind speed of the auxiliary wind turbine is lower than the starting wind speed of the main wind turbine, and the wind power generator transmits the rotation of the auxiliary wind turbine to the main wind turbine to start the main wind turbine, and A wind turbine generator, comprising: a transmission switching device (72) for canceling the transmission of rotation from the auxiliary wind turbine to the main wind turbine after the wind turbine starts to rotate.

10. The wind power generator according to claim 9, wherein the auxiliary wind turbine is arranged downstream of the main wind turbine.

1 1. The wind power generator further comprises:

An auxiliary generator (17) driven by the auxiliary windmill to generate power,

The wind power generator according to claim 9, further comprising: a connection switching device (33) that connects the auxiliary wind turbine to the auxiliary generator when a rotation speed of the main wind turbine is equal to or higher than a predetermined value.

1 2. The wind power generator further comprises:

A sensor (33a) for detecting a rotation speed of the main wind turbine, wherein the connection switching device includes an electromagnetic clutch for switching connection between the auxiliary wind turbine and the auxiliary generator based on a signal from the sensor. The wind power generator according to claim 11, characterized in that:

13. The main wind turbine has a plurality of main blades, the auxiliary wind turbine has at least one auxiliary blade, and the number of the auxiliary blades is less than the number of the main blades. Wind power generator according to any one of paragraphs 9 to 12

14. The method according to any one of claims 9 to 13, wherein the auxiliary wind turbine is stopped or decelerated when the rotation speed of the main wind turbine reaches a predetermined value or more.