Locking system for a rotatable mounted unit of a wind tur bine, wind turbine and method for operating a locking system

The present invention relates to a locking system for a ro tatable mounted unit of a wind turbine, comprising at least one locking means adapted to lock and unlock the rotatable mounted unit.

Typically, wind turbines comprise a tower and a nacelle lo cated on top of the tower, wherein the nacelle houses several components which convert the rotational energy of a rotating hub into electrical energy. To transfer this energy, a hub with several blades is connected with the generator by a main shaft and a bearing system.

Sometimes it is necessary to perform maintenance of rotating components of the wind turbine like the hub, the main shaft, the bearing system or the rotor. In this case, a technician has to work in the vicinity or even inside the respective ro tating parts of the wind turbine. In this situation, it is important to prevent the rotatable mounted unit of the wind turbine from rotating, because otherwise the technician is in danger. To avoid such situations, locking systems to prevent the rotatable mounted unit from rotating are provided.

WO 2012/059516 A2 discloses such a locking system for a ro tatable mounted unit of a wind turbine with a hydraulic sys tem adapted to drive cylinders to lock and unlock a rotatable part of the wind turbine. Once the cylinders have locked the rotatable mounted unit, valves are activated to change a door leading into a section of the wind turbine with the rotatable mounted unit from a locked state into an unlocked state. To unlock the rotatable mounted unit again, the door has to be closed. Another system for locking a hub of a wind turbine is dis closed in WO 2010/102967 A2. To lock the hub, pins are moved into respective openings to block a rotational movement of the hub. The openings are located on a flange of the hub and the pins are mounted on a base frame of a nacelle of the wind turbine. Means for fixing the pins in the locking position are provided.

It is an object of the present invention to provide an en hanced concept to lock a rotatable mounted unit of a wind turbine, in particular with respect to enable a safe and se cure maintenance work in the vicinity of the rotatable mount ed unit of the wind turbine.

To solve this problem, a locking system as stated above com prises a first prevention means and a second prevention means, wherein the locking means is prevented from changing from the locked state into the unlocked state if at least one of the prevention means is in a secure state, wherein a con trol unit is adapted to generate a control command changing the first prevention means into the secure state if the lock ing means currently locks the rotatable mounted unit, wherein the locking system is adapted to automatically change the second prevention means into the secure state if an access condition is fulfilled, wherein the access condition is ful filled if a recorded access information indicates that a room with the rotatable mounted unit is currently accessed or is going to be accessed via an entrance means.

Once the rotatable mounted unit is locked by the locking means, the first prevention means is automatically changed into the secure state. To initiate the change of the locking means from the unlocked or retracted state, where the rota tion of the rotatable mounted unit is possible, to the locked state, where the rotation of the rotatable mounted unit is not possible, and/or vice versa, the control unit can be adapted to generate a respective locking and/or unlocking command. This command can be triggered by a user via a con trol device or provided remotely.

After the locking means has reached the locked state, the first prevention means change into the secure state prevent ing the locking means to change back into the unlocked state unintentionally. This aspect of the invention represents a first protection layer of the locking system according to the present invention.

In particular to allow for the change of the locking means from the locked state into the unlocked state, the first pre vention means can be adapted or controlled to leave the se cure state. The first prevention means can be brought out of the secure state manually, e.g., by activating or switching the first prevention means by hand. Additionally or alterna tively, a control command causing the first prevention means to leave the secure state can be generated, in particular by the control unit. The respective control command can be gen erated if a first prevention means leaving condition is ful filled. Exemplarily, the first prevention means leaving con dition is fulfilled or can only be fulfilled if a respective control signal, e.g., generated by staff or automatically, is present or if the access condition is not fulfilled any more.

The locking system furthermore comprises a second protection layer to furthermore prevent the locking means to leave the unlocked state, wherein the second level basically acts inde pendently from the first prevention level. If the first pre vention means or the second prevention means or both are into the secure state, the locking means cannot change from the locked into the unlocked state.

The principle of the second protection layer is based on the idea that second prevention means are changed into the secure state depending on the access condition. The access condition can be fulfilled if a room or section of the wind turbine with the rotatable mounted unit is accessed, e.g. by the technician. Additionally or alternatively, the access condi tion can be fulfilled, if an access of the room with the ro tatable mounted unit is imminent.

Having the second prevention means into the secure state re liably prevents the locking means from changing from the locked state into the unlocked state if the access condition is fulfilled, e.g. if maintenance staff is currently working in the vicinity or the inside of the rotatable mounted unit. Even if the first prevention means accidentally leaves the secure state, the second prevention means ensures that the rotatable mounted unit remains in the locked state.

In particular, to allow the locking means to change from the locked state into the unlocked state, the second prevention means can be adapted or controlled to leave the secure state. The second prevention means can be brought out of the secure state manually, e.g., by activating or switching the second prevention means by hand. Additionally or alternatively, a control command causing the second prevention means to leave the secure state can be generated, in particular by the con trol unit. The respective control command can be generated if a respective control signal, e.g., generated by staff or au tomatically, is present or if the access condition is not fulfilled any more.

In a preferred embodiment, the first and/or the second pre vention means are switches adapted to disconnect the power supply of at least one actuator of the locking means. After the locking means have changed into the locked state, the switches cut off the actuator from the power supply. The ac tuator is only connected with the power supply if the switch es of both prevention means are not in the secure state. For this, the switches can be connected in series.

The at least one actuator can be a valve or of a hydraulic drive of the locking means. To change the locking means from the locked state into the unlocked state or vice versa, the flow direction of the valve can be changed electrically. The at least one actuator can be an electric motor, wherein the electric motor is adapted to change the locking means from the locked state into the unlocked state or vice versa.

In a preferred embodiment of the invention, at least one key station for storing a key to lock and unlock at least one en trance means for the room is provided, wherein the access in formation depends on whether the key is currently stored in or at the key station, wherein the access condition is ful filled if the key is removed from the key station. In other words, the access information says whether the key is cur rently present at the key station or not, wherein the access condition is fulfilled, if the access information says that the key is currently not present at the key station. The key station can be a key holder with a box to deposit the key.

The key can be a classic key to lock and unlock the entrance means. The key can also be a key card or a security token, in particular with an RFID-transponder. If several entrance means are provided, one key can be provided to lock and un lock all of the entrance means. Alternatively, several keys can be provided, wherein each key can lock and unlock at least to or all of the entrance means. Preferably, the number of keys equals the number of entrance means, wherein each key is assigned to a certain entrance means.

Once the key has been removed from the key station, the ac cess condition is fulfilled and, hence, the second prevention means changes into the secure state. Removing the key from the key station indicates that e.g. the technician intends to enter the respective room of the wind turbine with the rotat able mounted unit. Preferably, the removal of the key itself activates the switch of the second prevention means. This can be compared to the principle of many hotel rooms, where the removal of the key card automatically turns off the light in the hotel room. The key station can comprise a key receiver adapted to hold or carry the key when the key is stored in or at the key sta tion, especially for opening the switch. In this embodiment, the key can comfortably be deposited in or at the key sta tion. Particularly, the key being in the key receiver opens the switch of the second prevention means.

The key receiver can be a holding means like a hook or a lug or the like. Preferably, the key receiver is or comprises a key hole where the key is to be inserted for storage, where in, for storing the key, the key is inserted into the key hole and turned and, for removing the key, the key is turned back before it can be pulled out, wherein turning the key back before removing the key changes the second prevention means into the secure state or leaves the second prevention means in the secure state. In particular, the key is to be inserted in the key hole for storage and for activating the second prevention means. For removing the key, it can be turned, e.g. around an angle of 90° from a vertical into a horizontal position of the key head, and be pulled out. The key is preferably not removable from the key station, i.e. it cannot be pulled out from the key hole, while it is in the vertical position. Turning the key into the horizontal posi tion can automatically change the second prevention means in to the secure state. For storing the key, it can be plugged into the key hole and turned back into the vertical position. Turning the key into the vertical position can automatically cause the second prevention means to leave the secure state.

A further control unit can be adapted to generate a control command changing the second prevention means into the secure state if the key is removed from the key station. The remov ing of the key can be recorded by a sensor which is connected with the further control unit. Alternatively, the key station can be coupled with the second prevention means by a coupling mechanism adapted to change the second prevention means into the secure state when the key is removed from the key sta tion. The coupling mechanism can comprise a system of rag wheels or the like wherein in particular the turning of the key can change the current state of the second prevention means.

The key station can be a primary box which is connected with the second prevention means. Furthermore, the entrance means can comprise and/or can be dedicated to a key box to lock and unlock the respective entrance means. The key box can be a secondary box which is located close to or on the entrance means or, in particular, entrance door. The key box can com prise a key receiver which can be, like the key receiver of the key station, a slot or hole for the key.

Optionally, at least two key stations, each storing a key, can be provided, wherein the locking system can be adapted to automatically change the second prevention means into the se cure state if the key from at least one of the key stations is removed. Preferably, the number of key stations equals the number of entrance means. Assuming that all keys are stored at their respective key stations, the second prevention means is preferably automatically changed into the secure state if at least one of the keys is removed from the key station. Af ter this, other keys can be removed from the key station, wherein the second prevention means remain into the secure state. The second prevention means leaves the secure state if the last missing key is stored in its respective key station.

In a preferred embodiment of the invention, the control unit or a further control unit can be adapted to generate a con trol command changing the at least one key station into a state generally allowing the removal of the key from the key station, if the locking means currently locks the rotatable mounted unit. In this embodiment, a key which is stored in the key station is prevented from being removed if the rotat able mounted unit is not locked by the locking means. In par ticular, this can be realized by preventing the key from be ing turned or from being pulled out of the key hole. A signal light can be provided on the key station to show whether it is currently into the state generally allowing the removal of the key from the key station. If this is the case, the signal light can be green and otherwise red.

In a preferred embodiment, the control unit is adapted to generate a control command allowing the first prevention means to leave the secure state only if the at least one en trance means is closed. In particular, the control unit is adapted to generate the respective control command if all en trance means are closed. The expression "closed" particularly means that the respective entrance means is closed and locked. The control unit can be connected with a door sensor adapted to detect whether the entrance means is closed. This ensures that, in particular if the second prevention means are working incorrectly, the first prevention means remains in the secure state if not all access entrance means are closed.

Additionally or alternatively, the control unit is adapted to generate a control command allowing the first prevention means to leave the secure state only if the access condition is fulfilled, in particular if the or all of the key stations store their respective keys. In this embodiment, the first and the second prevention means can leave the secure state only if the access condition is fulfilled.

In an embodiment of the invention, at least one pad-lock can be provided, wherein the pad-lock can be attached to the at least one entrance means to mark and/or prevent the entrance means from being closed. Assuming several technicians are currently present at or in the wind turbine, each technician can have one respective pad-lock. If at least one of the technicians enters the room with the rotatable mounted unit, he has to attach the pad-lock to the respective entrance means. On the one hand, the presence of the pad-lock on the entrance means visually indicates that somebody is currently inside the room. On the other hand, the pad-lock can prevent the entrance means from being closed. The pad-lock can physi- cally block the respective entrance means from latching into the respective door or hatch lock. Preferably, each techni cian has a pad-lock key which only matches his respective pad-lock. Hence, the pad-lock cannot be removed from the en trance means before the respective technician has left the room with the rotatable mounted unit.

In an embodiment of the invention, at least one pin or latch of the locking means engages into at least one recess or a hole of the rotatable mounted unit for locking the rotatable mounted unit. The rotatable mounted unit can comprise a flange with several holes, wherein the pins are mounted at a non-rotating part of the wind turbine. For locking and un locking the rotatable mounted unit, the pins can be moved along their longitudinal pin axes into the radial direction with respect to the rotation axis of the rotatable mounted unit. The control unit can be connected with at least one sensor to detect the current state of the locking means. In particular, one sensor is provided to sense if the locking means is in the unlocked state. To avoid wrong detections in dicating erroneously that the locking means is in the locked state, two further sensors can be provided to detect the locked state. Based on this information, the control command to change the first prevention means into the secure state can be generated. One or more other breaking systems or breaks to lock the rotatable mounted unit can be provided.

Next, details of an especially preferred embodiment will be described. In this embodiment, the key is exemplarily a key card. The key receivers of the key station and the key box are slots for the key card. Removing the key card from the slot of the key station opens the switch of the second pre vention means. Inserting the key card into the slot of the key station closes the switch of the second prevention means. Inserting the key card into the slit of the key box allows it to open or automatically opens the entrance means. Prefera bly, the key is preferably non-removably or, in other words, fixedly attached to the key box while the entrance means is open. The key can only be removed from the key box if the en trance means is closed. Since each of the technicians has his own pad-lock and every technician who enters the room with the rotatable mounted unit attaches his pad-lock to the en trance means, the door is prevented from being closed and, hence, the key can only be removed from the key box until all people have removing their pad-locks from the entrance means after they have left the room.

Furthermore, the present invention relates to a wind turbine comprising at least one entrance means leading to a room with the rotatable mounted unit and a locking system as described above. The wind turbine can comprise one or several rooms with rotatable mounted units, wherein each of the rooms can be accessed by one or several entrance means. The entrance means can be a door or a hatch or the like leading into the room with the rotatable mounted unit.

In addition, the present invention relates to a method for operating a locking system for a rotatable mounted unit of a wind turbine, comprising at least one locking means adapted to lock and unlock the rotatable mounted unit, wherein a first prevention means and a second prevention means are used, wherein the locking means is prevented from changing from the locked state into the unlocked state if at least one of the prevention means is in a secure state, wherein the first prevention means is changed into the secure state if the locking means currently locks the rotatable mounted unit, wherein the second prevention means automatically changes in to the secure state if an access condition is fulfilled, wherein the access condition is fulfilled if a recorded ac cess information indicates that a room with a rotatable mounted unit is currently accessed or going to be accessed via an entrance means.

In particular to allow for a change of the locking means from the locked state into the unlocked state, the first preven tion means and/or the second prevention means can leave the secure state. The first prevention means and/or the second prevention means can be brought out of the secure state manu ally, e.g., by activating or switching the second prevention means by hand.

All features of the locking system according to the present invention and the respective advantages also apply to the wind turbine and the method according to the present inven tion and vice versa.

Further advantages and details of the invention can be taken from the embodiment below and the figures. The figures show schematically :

Fig. 1 An embodiment of a wind turbine according to the present invention, and

Fig. 2 a locking system of the wind turbine of Fig. 1.

Fig. 1 depicts a wind turbine 1 with a locking system 2, wherein details of the locking system 2 are shown in Fig. 2. The wind turbine 1 comprises several rotatable mounted units 3, namely a hub 4 with blades 5 and a main shaft 6 which con nects the hub 4 with a generator 8 via a bearing system 7 to convert the rotational energy of the hub 4 into electrical energy. The main shaft 6, the bearing system 7 and the gener ator 8 are located within a room 9 of a nacelle 10, which is located on top of a tower 11 of the wind turbine 1.

The room 9 with the rotatable mounted units 3 can be ac cessed, e.g. by a technician 12 to perform maintenance work on the rotatable mounted units 3, via an entrance means 13, namely a door 14 leading from a section 15 of the nacelle 10 without a rotatable mounted units 3 into the room 9. The en trance means 13 can also be a hatch or the like.

If maintenance work has to be performed on or in the vicinity of the rotatable mounted units 3, i.e. within the room 9, the rotatable mounted units 3 have to be locked. Otherwise the technician 12 could be in serious danger if the rotatable mounted units 3 start to rotate unexpectedly. Hence, a lock ing means 16 is provided to lock and unlock the rotatable mounted units 3, in particular the hub 4. The locking means 16 comprises a pin 17 which engages into a rotating part of the wind turbine 1, in particular into a hole 18 of the hub 4 or a flange of the hub 4 in a locked state. To change the locking means 16 from the locked state, where it locks the rotatable mounted unit 3, into an unlocked state, where it does not lock the rotatable mounted unit 3, the pin 17 can be moved along its longitudinal pin axis out of the hole 18 via a hydraulic drive 19 which comprises a cylinder 20 and valves 21. Alternatively, the locking means 16 can be driven by an electric motor (not shown).

The locking system 2 comprises a first prevention means 22 and a second prevention means 23. The prevention means 22, 23 are electrical switches 24 to connect and disconnect the pow er supply 25 of actuators 26 of the locking means 16, i.e. of the valves 21. If one of the prevention means 22, 23 is in a secure state, the respective switch 24 is open and the power supply 25 of the actuator 26 is interrupted. As a conse quence, the locking means 16 cannot change its current state, in particular it cannot change from the locked state into the unlocked state.

A control unit 27 is adapted to generate a control command changing the first prevention means 22 into the secure state if the locking means 16 currently locks the rotating part, in particular the hub 4. As a consequence, the locking means 16 is prevented from changing into the unlocked state uninten tionally. As a result, a first protection layer is realized preventing the rotatable mounted unit 3 from rotating while maintenance work is performed in the room 9. To sense the current state of the pin 17, the control unit 27 is connected with sensors 28, 29. The sensor 28 is used to sense if the locking means 16 is in the unlocked state. To avoid wrong de- tections indicating erroneously that the locking means 16 is in the locked state, two sensors 29 are used to detect this state. To allow the first prevention means 22 to leave the secure state, the control unit 27 is adapted to generate a respective control command.

To realize a second protection layer preventing the rotatable mounted unit 3 from rotating, the locking system 2 is adapted to automatically change the second prevention means 23 into the secure state if an access condition is fulfilled. The ac cess condition is fulfilled, if an access information indi cates that the room 9 is currently accessed or going to be accessed via the entrance means 13. Hence, even if the first prevention means 22 leaves the secure state erroneously, the open switches 24 of the second prevention means 23 prevent the locking means 16 to change into the unlocked state.

For instance five key stations 30 are provided for storing a key 31 each. Alternatively, the locking system 2 can comprise only one key station 30 adapted to store several keys 31. The keys 31 are adapted to lock and unlock the door 14 and/or other entrance means 13 leading into the room 9. Although the keys 31 are classic keys, the keys can also be key cards, se curity tokens, in particular with an RFID-transponder, or the like. The access information is fulfilled if at least one of the keys 31 is removed from its respective key station 30.

Each entrance means 13 comprises and/or is dedicated to one of five key boxes 32 to lock and unlock a dedicated entrance means 13. In Fig. 2, the key 31 of one key station 30 has been removed. As a consequence, also the second prevention means 23 has been changed into the secure state. The respec tive key 31 has been used at the key box 32 to unlock the door 14, which is the entrance means 13 which is dedicated to the key box 32.

It is only possible to unlock the door 14 and, hence, to get access into the room 9 after the respective key 31 has been removed from the key station 30 and inserted in the key box 32. The second protection layer is based on the idea that this removing of the key 31 from the key station 30 causes the change of the second prevention means 23 into the secure state. As a consequence, it is not possible to get access in to the room 9 while the second prevention means 23 is not in the secure state and, thus, while the rotatable mounted units 3 are not locked.

In other words, the only possibility to get access into the room 9, namely by removing the key 31 from the key station 30, causes an automatic change of the second prevention means 23 into the secure state. Furthermore, it is only possible to leave the second prevention means 23 from the secure state, after the key 31 is back again at its key station 30, which is only possible after the door 14 has been locked again.

Next, the key stations 30 will be described in more detail. Each of the key stations 30 comprises a key receiver 33, namely a key hole. To store the key 31 at the key station 30, the key is plugged into the respective key receiver 33. After this, the key 31 can be turned, e.g. around an angle of 90°, until the head of the key 31 is exemplarily into a vertical position. In this position, the key 31 cannot be removed from the key receiver 33. To remove the key 31, the key has to be turned back, e.g. around -90°, before it can be pulled out.

Assuming that all keys 31 are currently stored in the respec tive key stations 30, if one of the keys 31 is turned in or der to remove it, the second prevention means 23 automatical ly changes into the secure state. After this, further keys 31 can be removed from the key stations 30 which does not lead to a change of the secure state of the second prevention means 23. To leave the secure state of the second prevention means 23, all keys 31 have to be stored again in the key sta tions 30. In other words, only if the last of the missing keys 31 has been brought back to the key stations 30, the turning of this key 31 automatically closes the switches 24 of the second prevention means 23.

To change the current state of the second prevention means 23 when the key 31 is removed from or brought back to the key station 30, a, regarding the control unit 27, further control unit (not shown) is adapted to generate a respective control command. Alternatively but less preferred, the control unit 27 can be adapted to generate this control command. In a pre ferred embodiment, however, a mechanical coupling mechanism adapted to automatically change the second prevention means 23 into or leave it from the secure state when the key 31 is turned, is provided.

The control unit 27 is adapted to generate a control command changing the key stations 30 into a state generally allowing the removal of the keys 31, if the locking means 16 currently locks the rotatable mounted unit 3. Hence, if the rotatable mounted unit 3 is currently not locked, it is not possible to remove the keys 31 from the key stations 30. If the key sta tions 30 are in this state, signal lights 34 of the key sta tions 30 are green. Otherwise, the signal lights 34 are red or off.

Furthermore, the control unit 27 is adapted to generate a control command allowing the first prevention means 22 to leave the secure state only if all entrance means 13 are closed and locked. This control command can also be generated if the access condition is not fulfilled, i.e. if none of the keys 31 is removed from the key station 30. To detect whether the entrance means 13 are closed or locked, the control unit 27 is connected with the key boxes 32 and/or sensors (not shown) which are provided in the vicinity of the entrance means 13.

The locking system 2 comprises at least one pad-lock 35. If several technicians 12 are present at the wind turbine 1, each technician 12 has his own pad-lock 35. When entering the room 9, the respective technician 12 attaches his pad-lock 35 to the respective entrance means 13. This marks the door 14 to indicate that somebody is currently inside the room 9 and prevents the door 14 from being closed. The number of pad locks 35 attached to the entrance means 13 indicates the num ber of technicians 12 who are currently within the room 9.

As shown in Figs. 1 and 2, the technician 12 is currently working within the room 9 and has marked the door 14 with the pad-lock 35. Hence, it can be seen from the section 15 that somebody is currently inside of the room 9. Additionally, the pad-lock 35 physically prevents the door 14 from being closed and locked and, since the key 31 can only be removed from the key box 32 if the door is closed, the key 31 is prevented from being brought back to the key station 30. As a conse quence, the second prevention means 23 cannot leave the se cure state if the pad-lock 35 is attached to the door 14 and the technician 12 is inside the room 9.

In the following, details according to the method according to the present invention are described on the basis of the Figs. 1 and 2. To lock or engage the rotatable mounted units 3, the hub 4 has to be brought into a position where the pin 17 can engage into the hole 18. A turbine controller or, al ternatively, the control unit 27 changes the locking means 16 into the locked state by activating the hydraulic drive 19. This can be triggered by the technician 12 via a control de vice (not shown) of the wind turbine 1. Alternatively, a re spective signal can be generated from remote. After the lock ing means 16 has reached the locked state, the sensors 29 give a respective signal to the control unit 27.

Next, the control unit 27 generates the control command changing the first prevention means 22 into the secure state. To open the switches 24 of the first prevention means 22, the control unit 27 generates a control command. Another control command generated by the control unit 27 changes the key sta tion 30 into a state generally allowing it to remove the key 31. In addition, the signal light 34 turns from red or from the off-state into green colour. Next, one of the keys 31 is removed from the key station 30, e.g. by the technician 12, wherein the second prevention means 23 automatically changes into the secure state by opening the respective switches 24. The removed key 31 can now be inserted into the key box 32 of the entrance means 13 to unlock the entrance means 13. Next, the pad-lock 35 is attached to the door 14.

To unlock or retract the rotatable mounted units 3, all pad locks 35 have to be removed from the entrance means 13 after all technicians 12 have left the room 9. Next, the entrance means 13 are locked by the keys 31 which are then stored in the respective key stations 30. While the last key 31 is turned into the vertical position, the second prevention means 23 automatically leaves the secure state, i.e. the re spective switches 24 are closed. The key stations 30 provide a dual channel signal to the control unit 27 indicating that all entrance means 13 are closed and locked leading the con trol unit 27 to generate a control command which causes the first prevention means 22 to leave the secure state, i.e. to close the respective switches 24. Next the control unit gen erates a control command, e.g. to the turbine controller, which changes the locking means 16 into the unlocked state. After the locking means 16 has reached the unlocked state, the sensor 28 gives a respective signal to the control unit 27.

Although the present invention has been described in detail with reference to the preferred embodiment, the present in vention is not limited by the disclosed examples from which the skilled person is able to derive other variations without departing from the scope of the invention.