WO1995000757A1

WO1995000757A1 - Method and apparatus for the emergency shutdown of a wind energy plant

Info

Publication number: WO1995000757A1
Application number: PCT/FI1994/000274
Authority: WO
Inventors: Kari Rajalahti
Original assignee: Kari Rajalahti
Priority date: 1993-06-23
Filing date: 1994-06-20
Publication date: 1995-01-05
Also published as: FI932916A0; FI932916A; FI95960C; AU7001594A; FI95960B

Abstract

During an emergency shutdown the angle of attack of the wind rotor (2) to the wind (A) is minimized in such a way that the wind rotor (2) is pivoted by means of a tilting device (10) to the horizontal plane. When an emergency shutdown is carried out, the assembly composed of the wind rotor (2), machinery (3) and housing (4), which is connected at the housing to a sleeve part (8), is locked non-pivotally about the vertical axis of a supporting structure (5). A locking means (14) connects the sleeve part (8) and the supporting structure (5) so as to form an integral unit.

Description

Method and apparatus for the emergency shutdown of a wind energy plant

The invention relates to a method for the emer- gency shutdown of a wind energy plant, in which an as¬ sembly composed of a wind rotor, machinery, a housing and a tilting device pivots about the vertical axis of a supporting structure and in which during an emergency shutdown the wind rotor and machinery are pivoted about a horizontal axis relative to the supporting structure to reduce the angle of attack of the wind rotor to the wind.

A further object of the invention is to provide an apparatus for the emergency shutdown of a wind en- ergy plant, which wind energy plant is composed of a wind rotor, machinery connected so as to be rotated by the wind rotor, a housing to which the machinery is connected to pivot about a horizontal axis, a tilting device which is connected so as to affect the angle between the housing and the machinery, a bearing assem¬ bly comprising a sleeve part and bearings, whereby the assembly composed of the wind rotor, machinery, housing and tilting device is connected so as to pivot about the vertical axis of the supporting structure. In conventional wind energy plants, the modes of accomplishing an emergency shutdown vary greatly depending on the size of the plant. Similarly, orient¬ ing wind energy plants to face the wind is accomplished in a number of different ways. For example, in large wind energy plants the machinery has to be released first so that it is able to pivot about a supporting shaft and only thereafter can the machinery be orient¬ ed, for example, by means of electric motors, so that the rotor surface is optimally positioned in respect of the wind conditions, after which the machinery is lock- ed in place, for example, with a friction coupling. Accordingly, the use of such devices, for example, in accomplishing an emergency shutdown is slow and their use calls for continual maintenance and oversight owing to their complex construction.

U.S. Patent 4,674,954 discloses a control sys¬ tem for orienting a rotor, in which the orientation takes place by means of a tail assembly connected to the wind rotor and the machinery. The tail assembly is connected to the machinery by means of a hydraulic cy¬ linder, whereby extending the piston rod of the hy¬ draulic cylinder enables the position of the tail as¬ sembly to be changed in respect of the machinery. The purpose of the control system is mainly to compensate for the effects of gusty wind on the wind rotor, where¬ by rapid movement of the tail assembly carried out by means of the hydraulic cylinder makes it possible to change the angle of attack of the wind rotor to the wind. An apparatus of this type cannot, however, be used to carry out an emergency shutdown of a wind en¬ ergy plant because it does not allow the position of the wind rotor to be changed such that the wind has no effect upon it. Similarly, the machinery, including its wind rotor, cannot be locked in place in respect of the support beam.

Finnish Patent Application 813,150 discloses a wind energy plant safety device in which a very high wind causes the turbine to swivel in such a way that its plane of rotation is aligned with the wind. The apparatus calls for complex devices to detect the wind velocity and intensity as well as complex control de¬ vices. Neither does the system allow the effect of the wind on the machinery and the turbine to be minimized sufficiently. Similarly, the mechanical implementation is complex and thus expensive. British Patent Application 2,107,794 discloses an apparatus by means of which the oscillation of a wind rotor and machinery is reduced when the intensity of the wind varies. In the apparatus in question the wind rotor and its machinery are connected via a spring-loaded snubber to the tail assembly, and thus, when the wind presses with great force against the wind rotor, the wind rotor and its machinery can pivot such that the wind rotor is nearly horizontal. When the wind diminishes in intensity, the spring-loaded snubber places the machinery with its wind rotor back in normal operation. The apparatus nevertheless does not allow the wind rotor to be permanently set, for example, when making an emergency shutdown, in such a way that the angle of attack to the wind is as small as possible. The task of the apparatus is only to damp the movements of the wind rotor and machinery between the vertical and horizontal planes during high winds.

U.S. Patent 4,449,889 discloses a windmill in which a high wind causes a wind rotor to pivot nearly into a horizontal position. Further, an even higher wind will cause a tail assembly to guide the position of the wind rotor even more towards the horizontal, whereby the speed of rotation of the wind rotor dimin- ishes as the angle of attack of the wind becomes smaller. The entire machinery is nevertheless able to pivot about its supporting structures, whereby a change in the wind direction in gusty conditions causes the wind rotor with its machinery and the tail assembly to pivot back and forth about their supporting structures. In this case the structures are subject to great stresses owing to sudden changes in the direction and accordingly the structures must be dimensioned using a very large safety factor. This leads to very high manu- facturing costs. European Patent Specification 33,258 discloses a wind energy plant in which the wind rotor is made to face the wind by means of a separate apparatus. The apparatus is chain geared to the vertical axis of the machinery. Similarly, the wind rotor can be turned to a horizontal position by means of a separate spindle motor. Further, the spindle motor can also be used to control the position of the wind rotor between the ver¬ tical and horizontal planes. In a high wind the wind rotor is turned to the horizontal plane and the ma¬ chinery is locked by means of a chain-geared actuator so that it cannot pivot about the vertical axis. This chain-geared actuator cannot, however, endure great stresses and when employed as an emergency shutdown device it can easily cause hazardous situations and thus, owing to the high risk of damage, it can involve fairly high operating costs for the user of the appar¬ atus. Similarly, the complex mode of implementation involves very high manufacturing costs, which means that using the apparatus on farms, for example, becomes unprofitable.

The object of the present invention is to pro¬ vide a method and an apparatus enabling the emergency shutdown of a wind energy plant to be accomplished in an easy and simple manner and being reliable for the user.

This method is characterized in that the assem¬ bly composed of the wind rotor, machinery, housing and tilting device of the wind energy plant is connected non-pivotally in the horizontal plane in respect of the vertical axis of the supporting structure.

Further, this apparatus is characterized in that the supporting structure has in its upper part a locking means and that the locking means is connected so as to act upon the assembly composed of the wind rotor, machinery, housing and tilting device in such a way that when the assembly composed of the wind rotor, machinery, housing and tilting device is pivoted it locks non-pivotally in the horizontal plane in respect of the vertical axis of the supporting structure.

The essential idea of the method resides in the fact that in too high a wind or similarly when the electric generator overspeeds, a plant emergency shut¬ down is carried out and the wind rotor is pivoted to the horizontal plane in such a way that it presents the smallest possible angle of attack to the wind. Similar¬ ly, an essential idea is that when an emergency shut¬ down is taking place, the assembly composed of the wind rotor and machinery, which rotates about the vertical axis of the supporting structure, is locked in place, and therefore the wind is not able to turn the assembly composed of the wind rotor and machinery relative to the vertical axis of the supporting structure but in¬ stead it remains locked in position. Accordingly, the gyroscopic moments resulting from a change in the posi¬ tion of the spinning wind rotor are not able to turn the assembly composed of the wind rotor and machinery about the vertical axis of the supporting structure during an emergency shutdown. An essential idea of the apparatus according to the invention resides in the fact that its locking function is linked to the turning, during an emergency shutdown, of the wind rotor to the horizontal plane, and thus at the earliest possible stage the locking means locks the assembly composed of the wind rotor and machinery to be non-pivotal in respect of the vertical axis of the supporting structure. Further, an essential idea is that the means is implemented mechanically, enabling the assembly to be structurally as simple as possible. The advantage of the method according to the invention is that an emergency shutdown can be carried out in a completely controlled manner and the assembly composed of the wind rotor and machinery is not able to pivot by the action of the wind and gyroscopic moments in such a way that its structures are subjected to great stresses. Accordingly, the wind energy plant can be designed with a very small safety factor, making the assembly affordable in terms of its manufacturing, costs and at the same time easy to implement. Similarly, an essential advantage of the apparatus is its simplicity. Most preferably, it is possible to achieve, by means of one moving part, a controlled locking of the assembly composed of the wind rotor and machinery in respect of the supporting structure. Further, the simple solution can be positioned inside the machinery and the bearing assembly of the supporting structure, in which case it does not take up extra space.

The invention will be described in more detail in the accompanying drawings, in which

Figure 1 shows an emergency shutdown apparatus according to the invention when a wind energy plant is in operation and

Figure 2 shows the wind energy plant when an emergency shutdown is being carried out.

Figure 1 shows a wind energy plant 1 which is composed of a wind rotor 2, machinery 3, a housing 4 and a supporting structure 5. The wind rotor, which is completely known per se and will not be discussed in greater detail in this application, is connected to the machinery 3 by means of a shaft 6. The machinery 3 com¬ prises the necessary equipment for generating electri¬ city, such as an electric generator and a control unit enabling the power produced by the electric generator to be measured and controlled. Similarly, the machinery 3 also incorporates a coupling unit by means of which the electric generator can be disconnected from the electric network to be supplied. The wind energy plant 1 shown in Figure 1 is a freely windward-orienting en- ergy plant; when the wind is blowing from the direction indicated by arrow A, the wind turns the wind rotor 2 and the electric generator of the machinery 3, which is connected via the shaft 6 to the wind rotor 2, thereby generating electric energy to be supplied to the elec- trie network. The housing 4 is mounted on the support¬ ing structure 5 by means of a bearing assembly 7. The bearing assembly 7 is composed of a sleeve part 8 which is connected to the housing 4, and bearings 9a and 9b between the sleeve part 8 and the supporting structure 5. Accordingly, the assembly composed of the wind rotor 2, machinery 3 and housing 4 as well as their associ¬ ated devices is able to pivot, by means of the bearing assembly, freely about the vertical axis of the sup¬ porting structure 5 so as to face the wind. Also con- nected to the housing 4 is a tilting device 10, which can pivot about a shaft 11. Similarly, one end of the tilting device 10, which can most preferably be a hy¬ draulic cylinder, is connected to the machinery 3 by means of a shaft 12 so that it pivots about the shaft 12. The machinery 3 is connected to the housing 4 at its other end so that it can pivot about a shaft 13. A locking means 14, which most preferably is composed of a spring 15 and a splined coupling 16, is disposed in the supporting structure 5 in the middle of the bearing assembly 7. The supporting structure 5 is anchored to the ground in a manner known per se and will not be discussed in greater detail in this application. Fur¬ ther, it is to be noted that the separate electric con¬ trol circuits and electric switching devices of the machinery 3 can also be disposed in the base of the wind energy plant, enabling the assembly composed of the wind rotor, machinery and housing to form a simple and reliable entity.

Figure 2 shows the wind energy plant 1 in an emergency shutdown state. The reference numbers of Fig¬ ure 2 correspond to the numbering of Figure 1. When the intensity of the wind increases too much or when the electric generator is disconnected from the electric network owing to a network disturbance, the load on the machinery 3 is subjected to great changes in which the speed of rotation of the machinery 3 and, at the same time, of the wind rotor 2 can become excessively high. In this case, the controllers of the machinery 3 carry out a so-called emergency shutdown in which the wind rotor 2 and the machinery 3 are pivoted in such a way that the wind rotor 2 forms the smallest possible angle of attack to the wind A. Generally, the wind rotor 2 is pivoted to the horizontal plane. When the controllers detect a sudden great change in the load or an excess- ively large load, the tilting device 10 is activated and turns the machinery 3 into a vertical position, the wind rotor 2 being in a horizontal position. Simultan¬ eously, when the housing of the machinery 3 is disen¬ gaged from the locking means 14, the bearing assembly 7 couples with the supporting structure 5, whereby the assembly composed of the wind rotor 2, machinery 3 and housing 4 of the wind energy plant 1 is no longer able to pivot about the vertical axis of the supporting structure 5. Thus, a gusty wind or the gyroscopic mo- ments resulting from the rotation of the wind rotor are not able to turn the assembly composed of the wind rotor 2, machinery 3 and housing 4 suddenly in such a way that it is subjected to excessive stress owing to sudden movements, thus involving the danger of mechan- ical damage. When turning takes place, the machinery 3 with its wind rotor 2 pivots about the shaft 13 by the action of the tilting device 10. The tilting device 10 can be, for example, the above-mentioned hydraulic cy¬ linder, whose length can be controlled. The frame of the tilting device 10 is connected to the housing 4 by means of the shaft 11 and the piston of the tilting device 10 is connected to the front part of the ma¬ chinery 3 by the shaft 12. Accordingly, when the ma¬ chinery 3 pivots about the shaft 13, the angle of the tilting device 10 to the housing 4 and the machinery 3 is also changed, this being accomplished by means of the shafts 11 and 12. Various kinds of spindle motors can also serve as the tilting device 10. Since the housing 4 is connected rigidly to the sleeve part 8 of the bearing assembly 7, the locking means 14 serves to lock the entire wind energy plant into an integral unit, in which case the assembly composed of the wind rotor 2, machinery 3 and housing 4 of the wind energy plant 1 is not able to pivot about the vertical axis of the supporting structure 5. As has been mentioned above, the locking means 14 is most preferably a device consisting of a spring 15 and a splined coupling 16, and the sleeve part 8 of the bearing assembly 7 has a hole 17 whose edges are provided with splines and which substantially corresponds to the shape of the splined coupling 16. Similarly, the walls of the casing 18 of the spring 15 of the supporting structure 5 are pro¬ vided with splines which correspond to the splines of the hole 17 of the sleeve part 8 and thus conform sub- stantially to the shape of the splined coupling 16. Thus, when the machinery 3 ascends, the spring 15 pushes the splined coupling upwards in the splines of the casing 18. Having ascended to a sufficiently high level, the splined coupling 16 encounters the splines of the hole 17 of the sleeve part 8 and thereby locks the supporting structure 5 and the sleeve part 8 into an integral unit. Since, furthermore, the assembly com¬ posed of the wind rotor 2, machinery 3 and housing 4 is connected rigidly to the sleeve part 8, the above-men- tioned assembly also locks rigidly in respect of the vertical axis of the supporting structure 5. It is to be noted that the locking means 14 is to be formed in such a way that the necessary cabling can be carried out via the locking means 14. Similarly, when the wind energy plant 1 is put back into operation, the wind rotor 2 and the machinery 3 are lowered in such a way that the wind rotor 2 is in a vertical position and the machinery 3 is in a horizontal position. Now the ma¬ chinery 3 presses the splined coupling 16 downwards, whereby the splines of the hole 17 of the sleeve part 8 are released from the splines of the splined coupling 16, and the assembly composed of the wind rotor 2, ma¬ chinery 3 and housing 4 can again pivot about the ver¬ tical axis of the supporting structure 5. Further, it is possible to implement the locking means 14 in such a way that the mechanical coupling takes place before the machinery and the wind rotor are lifted. In this case, the locking means 14 locks the sleeve part and the supporting structure in some other corresponding way such as, for example, by urging the spring 15 with a separate actuator, which is triggered before the pivoting of the wind rotor 2 and machinery 3, whereby the above-mentioned assembly is locked completely non- pivotally relative to the vertical axis of the support- ing structure 5. This precludes a situation in which the locking means 14 is only partly lockable into the sleeve part.

The invention and the description relating thereto are intended solely to illustrate the spirit of the invention. In its details the invention can vary within the scope of the claims. Accordingly, for ex¬ ample, the locking means according to the invention can be used in any wind energy plant, and particularly in plants that freely seek a windward orientation.

Claims

1. A method for the emergency shutdown of a wind energy plant, in which an assembly composed of a wind rotor (2), machinery (3), a housing (4) and a tilting device (10) pivots about the vertical axis of a supporting structure (5) and in which during an emer¬ gency shutdown the wind rotor (2) and machinery (3) are pivoted about a horizontal axis (13) relative to the supporting structure (5) to reduce the angle of attack of the wind rotor (2) to the wind (A), c h a r a c ¬ t e r i z e d in that the assembly composed of the wind rotor (2), machinery (3), housing (4) and tilting device (10) of the wind energy plant (1) is connected non-pivotally in the horizontal plane in respect of the vertical axis of the supporting structure (5).

2. A method according to claim 1, c h a r ¬ a c t e r i z e d in that a locking means (14) is ac¬ tivated by pivoting the wind rotor (2) and machinery (3) about a horizontal axis relative to the supporting structure (5).

3. A method according to claim 1, c h a r ¬ a c t e r i z e d in that the locking means (14) is activated, before the wind rotor (2) and machinery (3) have pivoted about the horizontal axis of the support¬ ing structure, under the control of a separate control¬ ler.

4. A method according to any one of the preced¬ ing claims, c h a r a c t e r i z e d in that the wind rotor (2) is pivoted substantially into a hori¬ zontal position.

5. An apparatus for the emergency shutdown of a wind energy plant, which wind energy plant (1) is com¬ posed of a wind rotor (2), machinery (3) connected so as to be rotated by the wind rotor (2), a housing (4), to which the machinery (3) is connected so as to pivot about a horizontal axis (13), a tilting device (10), which is connected so as to affect the angle between the housing (4) and the machinery (3), a bearing assem- bly (7), consisting of a sleeve part (8) and bearings (9a, 9b), whereby the assembly composed of the wind rotor (2), machinery (3), housing (4) and tilting device (10) is connected so as to pivot about the ver¬ tical axis of a supporting structure (5), c h a r a c - t e r i z e d in that the supporting structure (5) has in its upper part a locking means (14) and that the locking means (14) is connected so as to act upon the assembly composed of the wind rotor (2), machinery (3), housing (4) and tilting device (10) in such a way that when the assembly composed of the wind rotor (2), ma¬ chinery (3), housing (4) and tilting device (10) is pivoted it locks non-pivotally in the horizontal plane in respect of the vertical axis of the supporting structure (5).

6. An apparatus according to claim 5, c h a r ¬ a c t e r i z e d in that the locking means (14) is connected so as to act when the angle between the ma¬ chinery (3) and the housing (4) changes.

7. An apparatus according to claim 5, c h a r - a c t e r i z e d in that the locking means (14) is connected to act under the control of a separate con¬ troller.

8. An apparatus according to any one of claims 5-7, c h a r a c t e r i z e d in that the locking means (14) is formed of a spring (15), a splined coup¬ ling (16) that is cross-sectionally angular, a casing (18) that is cross-sectionally substantially of the shape of the splined coupling (16), and a hole (17) in the sleeve part (8), which hole is cross-sectionally substantially of the shape of the splined coupling (16), whereby when the locking means (14) is activated, the spring (15) pushes the cross-sectionally angular splined coupling (16) into the hole (17) of the sleeve part (8) and locks the sleeve part (8) non-pivotally in the horizontal plane.

9. An apparatus according to any one of claims 5-7, c h a r a c t e r i z e d in that the supporting structure (5) has at its upper end a cross-sectionally angular part, that a splined coupling (16) is slidably mounted on the angular part, and that the outer circum¬ ference of the splined coupling (16) is angular such that when the spring (15) presses the splined coupling (16) into the hole (17) in the sleeve part (8), which hole is cross-sectionally substantially of the shape of the outer circumference of the splined coupling (16), the splined coupling (16) locks the sleeve part (8) non-pivotally in the horizontal plane in respect of the vertical axis of the supporting structure (5).

10. An apparatus according to any one of claims 5-9, c h a r a c t e r i z e d in that the wind energy plant (1) is freely orientable in a windward direction.