EP4222388A1

EP4222388A1 - Method for extending the service life of a main bearing assembly of a wind turbine

Info

Publication number: EP4222388A1
Application number: EP21789629.9A
Authority: EP
Inventors: Mathias Pick
Original assignee: Eolotec GmbH
Current assignee: Eolotec GmbH
Priority date: 2020-10-02
Filing date: 2021-10-01
Publication date: 2023-08-09
Also published as: US20230235783A1; WO2022069736A1

Abstract

The invention relates to a method for extending the service life of a main bearing assembly (1) of a wind turbine (4), comprising at least one main bearing (10) with a rotation axis (13) with at least one bearing row (2), in which main bearing a rotor shaft (3) of the wind turbine (4) is mounted, wherein the main bearing assembly (1) has at least one stationary bearing ring (7), a circulating bearing ring (8) and rolling elements (9). According to the invention the stationary bearing ring (7) is rotated about the rotation axis (13) of the main bearing assembly (1) to extend the service life or for servicing. Alternatively, only a new stationary bearing ring (7), preferably with at least two bearing ring segments (14) is installed instead of the damaged outer ring (7), in particular without further essential bearing components such as the inner ring being exchanged.

Description

description

Method for extending the service life of a main bearing assembly of a wind turbine

The invention relates to a method for extending the service life of a main bearing arrangement

Background of the invention:

Wind turbines have become one of the most important pillars of regenerative energy supply. For wind turbines, an operating life of at least 20 years was previously planned, and according to current developments, periods of up to 30 years are being sought. Nevertheless, in recent years it has been shown that wind turbines in the power class >1.5 MW in particular do not always meet these 20-year requirements for all components and that premature damage occurs, for example in the main bearing arrangement. With the main bearing arrangement, a rotor shaft is supported by means of a main bearing. The hub with the rotor blades is attached to the rotor shaft.

So far, in the event of damage, the entire drive train has been lifted off the nacelle with a crane and replaced with a new or revised drive train or repaired on the ground. Due to the rotor masses of 30-90t and hub heights of up to 160m, very expensive and often poorly available special cranes are required for this. The high costs associated with this lead to a significant reduction in yield up to the inefficiency of repairing the main bearing and thus the entire wind turbine. This problem becomes significantly more important when you consider the costs and logistical aspects associated with dismantling the rotors of an offshore wind turbine. EP 3 333 439 B1 and WO 2020/169762 A1 already contain concepts for replacing a main bearing of a wind turbine, in which the rotor shaft does not have to be dismantled and the drive train therefore does not have to be lifted from the nacelle.

In general, new maintenance and repair approaches are sought in order to keep the maintenance costs and thus the electricity generation costs reasonable and ultimately to ensure the competitiveness of this future technology.

Object of the invention:

The invention is based on the object of making it possible to repair and thus extend the service life of a damaged main bearing arrangement of a wind turbine with little effort.

Solution of the task:

The object is achieved according to the invention by a method for extending the service life with the features of claim 1 or with the features of claim 2. Preferred developments are contained in the dependent claims.

The main bearing arrangement of the wind turbine has at least one main bearing with a number of bearing rows, in particular one, two or three bearing rows, with a rotor shaft being rotatably mounted about an axis of rotation with the main bearing. Furthermore, the main bearing arrangement usually has a generally fixed housing which is fastened to a base frame of the wind turbine. The main bearing arrangement, specifically the main bearing, has at least one stationary bearing ring, a rotating bearing ring and rolling elements and typically also a cage. In operation, the rotating bearing ring rotates about the axis of rotation and the stationary bearing ring does not rotate. The bearing rings are located inside the housing. In the method for repairing and thus extending the service life of the main bearing arrangement, a first variant of the invention now provides for the stationary bearing ring to be rotated about the axis of rotation and rotation of the rotor shaft and thus the main bearing arrangement. It is therefore rotated about the axis of rotation and rotation of the rotor shaft and thus of the main bearing arrangement by a specific, limited angle of rotation, the angle of rotation not being equal to n*360°, where n is an integer. Therefore, after rotation, the individual sections/zones of the stationary bearing ring are in a different angular position compared to the previous, untwisted position.

As a result of the rotation, a zone of the fixed bearing ring that was previously under less load is rotated into an area in which higher loads occur during operation. The rotation preferably takes place by at least 45°, by at least 90° and preferably in an angular range of 160° to 200°, especially 180°. Maximum rotation is 270°.

According to a second variant of the invention, it is provided that in particular only the stationary bearing ring is replaced by a new stationary bearing ring. The new bearing ring is, in particular, a bearing ring that is divided into at least two segments in the circumferential direction, in order to enable assembly when the rotor shaft is assembled.

In this case, preferably no other (essential) bearing components are exchanged. The main bearing components include, in particular, the rotating bearing ring and/or the cage. Ie in particular the rotating bearing ring is not exchanged. The rolling bodies are also preferably not exchanged, at least some of the rolling bodies are not exchanged. The rolling elements are therefore also important bearing components. It is therefore preferred to replace only the damaged stationary bearing ring and not the entire bearing. The rotation or the replacement of the stationary bearing ring is carried out after a certain period of operation, typically several years, when the first signs of wear are visible.

These concepts are based on the common knowledge that the main storage arrangement has a systematic damage pattern that differs from the previously recognized scientific design and calculation bases. When designing a wind turbine with a service life of 20 or 30 years, the bearing has so far been dimensioned based on the service life and static safety. The basis for this is Hertz's fatigue theory and the evaluation of the pressure in the rolling contact. A total service life of the roller bearing is calculated on the basis of this design and the assumption that the rotating bearing ring is the first to tire.

The invention is now based on the new finding that this lifetime theory cannot be fully transferred to this application and that a different type of damage process superimposes or completely suppresses this assumed damage. This consideration results in a preferred failure of the stationary bearing ring of the roller bearing before damage to the rotating bearing ring and the roller bodies, which reduces the function, occurs.

The above-described approaches build on this new understanding to provide a new maintenance method for wind turbine main bearing assemblies.

In general, it is provided that the measures presented here for both variants are carried out without dismantling the rotor shaft. This means that the rotor shaft remains at least essentially in the position it occupies during operation, except for a possible support. Therefore, no complex removal of the hub and/or the rotor shaft is required and provided. During the repair, the rotor shaft is preferably supported with the aid of a holding device, a so-called fixture, in order to at least partially absorb the load of the rotor shaft during the repair, ie while rotating or replacing the stationary bearing ring. On the one hand, this fixture is supported on a structural component, such as the mentioned base frame or another part of the building of the wind turbine, especially the nacelle. On the other hand, the fixture is supported on the rotor shaft or on a component connected to it, such as the hub. The at least partial load release of the rotor shaft simplifies the repair work. The fixture is usually only attached temporarily during the repair measure.

In the case of a multi-row bearing, in which several bearing rings are arranged one behind the other in the direction of the axis of rotation, which are also designed, for example, as separate or non-destructively separable bearing rings, preferably only one bearing ring, in particular the axial bearing ring that is subjected to higher loads or is usually damaged, is replaced or rotated . Preferably, only the bearing ring facing away from the rotor hub is exchanged or rotated. The bearing rings arranged axially one behind the other are also referred to as axial bearing ring segments. Alternatively, several or all of the axial bearing ring segments can be exchanged or rotated.

In a preferred embodiment, the (bearing) housing is dismantled before the respective measure. This means, on the one hand, that the housing is released and, for example, that it is moved axially, so that the stationary bearing ring, which is usually an outer ring, is accessible. On the other hand, disassembly also means complete removal of the (used) housing. In this case, the housing is preferably replaced by a new housing, which is a so-called split housing, which consists of at least and typically exactly two housing segments. Such methods can be found, for example, in EP 3 333 439 B1 cited at the outset or WO 2020/169762 A1. The measures described here are used in particular with a stationary outer ring. This means that the outer ring forms the stationary bearing ring and the inner ring forms the revolving bearing ring, which rotates together with the rotor shaft during operation.

Alternatively, the measures described are used in a bearing variant in which the outer ring rotates during operation and the inner ring is stationary and does not rotate. In this variant, the "rotor shaft" is therefore stationary and forms a kind of axle journal. The rotor of the wind turbine is connected to the outer ring, e.g. via the rotating/rotating housing. This design is often found in directly driven wind turbines.

According to a first variant, the measure for extending the service life is carried out after a defined service life of typically several years, e.g. after 8 to 15 years after initial commissioning (for the first time and in particular also once).

According to a preferred embodiment, the measure is carried out as required when the bearing shows predetermined signs of wear or when it reaches wear limits. For this purpose, condition monitoring for the warehouse is provided in particular. As soon as relevant damage is detected, the desired repair and thus service life extension is initiated. To detect whether damage has occurred, vibration monitoring, load monitoring, bearing clearance monitoring, etc. are carried out as part of bearing monitoring.

The measures described here are generally preferably carried out only once during the service life of a wind turbine.

Especially in the second variant, in which an exchange of the stationary bearing ring is provided, in a preferred further development the bearing clearance, ie the bearing play, can be adjusted. This allows an optimal operating point of the bearing arrangement to be set. The new bearing ring, which is typically formed by several, for example 2, bearing ring segments adjoining one another in the circumferential direction, is suitably designed for this purpose.

In addition or as an alternative, when the housing is replaced, the new housing, which is also typically formed by a plurality of housing segments adjoining one another in the circumferential direction, is suitably designed.

The setting of the bearing clearance and/or the bearing preload, also referred to as bearing play, takes place in a manner known per se. For example, a parting line is formed between the individual segments for this purpose and an adjustment can be made, for example, with adjustment plates.

Measures for measuring and adjusting the bearing clearance of a main bearing can be found in EP 2 801 729 A2.

For the first variant with the rotation of the stationary bearing ring by a predetermined angle of rotation, in particular without dismantling the housing, a rotating device is provided in an expedient embodiment, which is preferably attached only temporarily and which performs or supports the rotation of the bearing ring.

One variant specifically provides for the bearing ring to be rotated within the (old) housing. In this variant, therefore, no dismantling of the housing, or at least no replacement with a new housing, is necessary. Rather, only the stationary bearing ring is released so that it can be rotated relative to the housing. It is then rotated within the housing and relative to it by the desired angle of rotation before it is then fixed again.

In this case, the bearing in particular is initially relieved, for example by the weight force being intercepted, for example, via the rotor and the fixture already mentioned. The rotary device is generally supported on a first structural component, for example on the base support, and engages in a positive and/or non-positive manner on the stationary bearing ring in order to rotate it.

In order to rotate the stationary bearing ring, its fixation, typically on the housing, is generally released so as to allow rotation.

In order to facilitate turning, especially turning within the housing 5, a temperature treatment, e.g. cold or heat treatment of the relevant components is also provided in a preferred embodiment. For example, heating of the housing can be provided so that it is easier to rotate the bearing ring.

The measures according to the invention, in particular the rotation, are described below by way of example using the figures and using a typical three-point bearing used in wind turbines. The figures show in simplified representations:

1 shows a sectional view of a main bearing arrangement of a wind turbine,

2 shows a perspective view of a detail of a wind turbine in the area of a hub without showing a housing (nacelle) for the main bearing arrangement

3A, 3B representations of a double-row main bearing in section and as a perspective

4A, 4B representations of the type of exploded representations of an outer ring and an inner ring in section and as a perspective

In the case of the wind turbine 4 shown in FIG. 1 and FIG. 2, a main bearing arrangement 1 designed as a 3-point bearing is provided. This common main bearing solution uses a double row spherical roller bearing as the rotor side Fixed bearing (main bearing 10) and a first gear stage bearing as a floating bearing on the transmission side. The main bearing 10 has a housing 5 which is attached to a support structure, for example a base frame 6 . The entire main bearing arrangement 1 is usually arranged in a gondola, not shown here, which is rotatably arranged on a tower, also not shown here.

The main bearing 10 has a stationary bearing 7 fixed by the housing 5 and forming an outer ring of the spherical roller bearing. Furthermore, the main bearing 10 has an inner ring which, during operation, rotates about an axis of rotation 13 together with a rotor shaft 3 and forms a circumferential bearing ring 8 .

Between the two bearing rings 7.8 rolling elements 9 are arranged. The bearing rings 7, 8, in particular the stationary bearing ring 7, have two rings which follow one another in the axial direction, ie in the direction of the axis of rotation 13 and which are also referred to as axial bearing ring segments. (In the upper half of FIG 4, a stationary bearing ring 15 divided into two axial bearing ring segments is shown as an example.) A row of rolling elements 9 is arranged between a respective inner and outer bearing ring segment, so that two bearing rows 2, namely a hub-side bearing row and a gear-side bearing row Bearing series are formed.

The load zones of this stationary bearing ring 7 or the stationary axial bearing ring segments caused by the wind loads are mirror images of each other on the hub-side bearing row between 9 and 3 o'clock and on the gear-side bearing row between 3 and 9 o'clock.

According to the state of the art, the service life theory and calculation of the load rating are based on the alternating shear stress hypothesis. For this purpose, on the basis of Hertz's pressure and empirically determined material parameters, the service life is estimated. According to this theory, the inner ring is usually the first component to fail, as this is due to the larger Curvature in the rolling direction usually sees the highest stress/compression.

However, application-specific experience shows that these assumptions are only partially correct and that other effects overlay this hypothesis. Kinematic and lubrication characteristics of the main bearing lead to a different failure sequence of the individual rolling bearing components. This new insight is the starting point for this new approach to maintenance. Experience shows that the stationary bearing ring 7 on the gear-side bearing row fails first, escaping the previous fatigue theory of the original bearing design. The rotating bearing ring 8 also shows slight signs of wear at this point. However, it is still fully functional, the same applies to the rolling elements 9 and a cage in which the rolling elements 9 are held.

It is therefore advantageous to detect damage to the stationary bearing ring 7 (outer ring) as early as possible with a monitoring system (condition monitoring, e.g. vibration monitoring, axial play monitoring) in order to avoid major breakouts in the outer ring raceway, which in turn could damage the rotating bearing ring 8 and the rolling elements 9.

Rather, experience has shown that early outer ring damage is mostly localized to the area between 3 a.m. and 9 a.m. Which in turn means that the remaining 180° of the outer ring are still almost new.

The invention now makes use of this connection and has developed a method for rotating this stationary bearing ring 7 (outer ring) on the wind turbine by 180° about the axis of rotation 13 when the rotor is mounted. What is thus achieved is that the undamaged raceway area of the stationary bearing ring 7 can be used and thus the overall service life of the main bearing arrangement 1 is extended without having to replace the entire main bearing 10 . In order to rotate this stationary bearing ring 7 (variant 1) or, if necessary, to replace it with a new bearing ring 7 (variant 2), the bearing 7 is first removed from its stationary position. In variant 2, the old bearing 7 is replaced by new bearing ring segments 14 (see FIG. 4), which form the new bearing ring 7.

Here is another special aspect, since in a preferred embodiment, the stationary housing 5 is separated from the nacelle structure, ie in particular from the base frame 6, to which the housing 5 is firmly connected during operation. The housing 5 is displaced spatially and temporally, despite the rotor and wind loads still present on the rotor shaft 3.

For this purpose, a fixture, not shown in detail in the figures, is provided, which fixes the rotor 11 , together with the rotor shaft 3 and the rest of the main bearing 10 , while the stationary bearing ring 7 is rotating. In the present case, rotor 11 is understood to mean the unit consisting of the so-called rotor hub 18 with the rotor blades arranged thereon. In the exemplary embodiment, the rotor hub 18 is connected in a torque-proof manner to the rotor shaft 3, which can also be regarded as part of the rotor. This fixture is connected to one or more of the structural components selected from the base frame 6, rotor shaft 3, rotor hub 18 and/or gearbox and is removed again after the bearing play or axial play of the main bearing arrangement 1 has been set and the bearing housing 5 has been re-attached to the base frame 6. For example, the fixture is supported on the one hand on the base frame 6 and on the other hand on the rotor hub 18 or the rotor shaft 3 in order to make the main bearing 10 at least partially load-free.

Another alternative embodiment of the repair is to turn the stationary bearing ring 7 directly in the bearing housing 5. For this purpose, preferably only add-on or conversion parts, such as cladding or cover elements, seals, etc., are dismantled and the rotor shaft 3 is further removed, for example by means of at least a hydraulic or mechanical support element (partially) relieved. The stationary outer ring 7 in the housing 5 is then rotated about the axis of rotation 13 of the rotor shaft 13 with the aid of a rotating device. In general, the turning device is preferably fastened to the housing 5 and/or the base frame 6 for all turning variants.

For the rotation of the stationary bearing ring 7 or at least one stationary axial bearing ring segment within the housing, without dismantling it, proceed as follows with such a three-point bearing, for example:

First, the rotor shaft 3 is secured against rotation by means of a rotor lock and the rotor weight is lifted by means of hydraulic tools, thus partially relieving the load on the main bearing arrangement. The conversion parts are then removed from the existing housing 5 in order to gain access to the stationary bearing ring 7 (outer ring). The rotating device is now attached to the housing 5 and/or to the base frame 6. This rotary device engages in a suitable manner (non-positive, positive, material or frictional) on the stationary bearing ring 7 and rotates it relative to the housing 5 about the axis of rotation 13. The rotation can be carried out in small sections by adjusting the rotary device accordingly. as well as a complete rotation by, for example, 180°, insofar as the rotating device allows this. Once the stationary bearing ring 7 has been rotated into the desired position, the rotary device is dismantled and the bearing is loaded again. The conversion parts are then reassembled and the rotorlock unlocked.

In the variant of replacing the stationary bearing ring, for example, the procedure is as follows:

Similar to what was previously described, the bearing is first relieved (secured via rotor lock, lift rotor weight...). The housing 5 is then dismantled, if necessary it is separated (for example by separating welding or other destructive separating process). Then (only) the stationary bearing ring 7 is removed, for this purpose it is divided into segments; if necessary, the bearing ring 7 is also destroyed here by separating it into the segments (separation welding, blasting). Thereafter, the bearing ring segments 14 (at least two) of the new stationary bearing ring 7 are mounted. If necessary the bearing clearance/bearing play is adjusted, for example by arranging spacer elements (shim plates) between the bearing ring segments 14. The housing 5 (if necessary a new one) is then reinstalled. For this purpose, this is typically divided into at least two housing segments. The bearing clearance can also be adjusted here. The housing 5 is then attached to the base frame/base support. The bearing is then loaded again (remove fixture, loosen rotorlock) and can be put back into operation.

The two variants described above (turning/replacing) can also be combined insofar as the housing is first dismantled in the first variant of turning the stationary bearing ring and then reassembled after turning or replaced with a new one.

The methods described here are basically also suitable for a moment bearing, which represents a special design of the main bearing in wind turbines. In this design, the bearing rings 7 , 8 are installed only partially or not at all in a housing or are secured in the housing 5 or on the rotor shaft 3 by the known interference fit. Rather, the bearing rings 7, 8 are fastened to the base frame 6, rotor hub 18 or other stationary and rotating structural components by means of a flange connection by means of screws. The stationary position relative to the base frame 6 or to the rotating rotor hub 18 is thus ensured with the aid of the screw connection and the frictional connection in the flange connection. Turning or replacing the stationary bearing ring 7 according to the invention is hereby just as advantageous as with the conventional three-point bearing.

A fixture is also provided for this purpose, which fixes the rotating part of the drive train (including the rotor, shaft and generator) to the standing base frame 6 . The flange connection of the stationary bearing ring 7 is then released and then rotated about the axis of rotation 13 of the bearing into an advantageous, low-wear position. After the flange connection has been re-attached, the fixture can be removed again and the rotor can be used again turn, or the wind turbine can be put into operation. If necessary, conversion parts must also be dismantled in advance in order to gain access to the flange connection. Torque bearings are very often used in directly driven wind turbines. A directly driven wind turbine is generally understood to be a system without gears, where the generator rotates at the same speed as the rotor. In this embodiment, the generator can preferably be used for temporary fixation and anti-twist protection. The fixture can thus be replaced in whole or in part, and the generator structure is used, according to a preferred embodiment, for rotating or replacing the stationary bearing ring 7 .

If the term rotor is used here, then this is understood to mean the rotating part of a wind turbine, which in particular includes the rotor hub 18 with the rotor blades attached thereto. Typically, the rotor also includes the rotor shaft 3, which is supported by the main bearing arrangement 1. The rotor shaft 3 is typically passed through the main bearing 10 and extends from the hub to a gearbox or to the generator in the case of directly driven wind turbines

Insofar as the main bearing arrangement is mentioned here, this is generally understood to mean the bearing of the rotor shaft 3 of a wind turbine, at the front end of which the rotor hub 18 with the rotor blades is fastened.

A fixture is generally understood to mean a holding device which is temporarily attached to a structural component such as the base frame 6 or another base or machine support and which is used in particular to temporarily support and hold the rotor shaft 3 while the measure described here is being carried out.

In the following, some process sequences with the individual process steps are shown as examples for rotating or replacing the stationary: Example 1 :

1.1 Fixing the rotor shaft 3 to the rotor hub 3 and base frame 6 using a fixture

1.2 Disassembly of the housing 5 and axial displacement of the housing 5

1.3 Rotating the stationary bearing ring 7 about the axis of rotation 13

1.4 Assembly of the housing 5 on the turned, stationary bearing ring 7

1.5 Disassembly of the fixture

1.6 Continued operation of the wind turbine (rotation of the rotor)

example 2

2.1 Fixing the rotor shaft 3 to the rotor hub 3 and base frame 6 using a fixture

2.2 Disassembly of the housing 5 and axial displacement of the housing 5

2.3 Removing the used stationary bearing ring 7

2.4 Assembly of the new bearing ring segments 14 of the stationary bearing ring 7

2.5 Assembly of the housing 5 on the segmented stationary bearing ring 7

2.6 Disassembly of the fixture

2.7 Continued operation of the wind turbine (rotation of the rotor)

Example 3

3.1 Fixing the rotor shaft 3 to the rotor hub 3 and base frame 6 using a fixture

3.2 Removal of the housing 5

3.3 Rotating the stationary bearing ring 7 around the axis of rotation 13 or installing new bearing ring segments 14

3.4 Assembly of new housing segments

3.5 Disassembly of the fixture

3.6 Continued operation of the wind turbine (rotation of the rotor)

example 4

4.1 Fixing the rotor shaft 3 to the rotor hub 3 and base frame 6 using a fixture

4.2 Disassembly of the housing 5 and axial displacement of the housing 5 4.3 Removing the used stationary bearing ring 7

4.4 Assembly of the new bearing ring segments 14 of the stationary bearing ring 7

4.5 Adjustment of bearing clearance

4.6 Assembly of the housing 5 on the segmented stationary bearing ring 7

4.7 Disassembly of the fixture

4.8 Continued operation of the wind turbine (rotation of the rotor)

Example 5

5.1 Fixing the rotor shaft 3 to the rotor hub 3 and base frame 6 using a fixture

5.2 Removal of the housing 5

5.3 Rotating the stationary bearing ring 7 around the axis of rotation 13 or installing new bearing ring segments 14

5.4 Assembly of new housing segments

5.5 Adjustment of bearing clearance

5.6 Disassembly of the fixture

5.7 Continued operation of the wind turbine (rotation of the rotor)

Example 6

6.1 Setting a rotor lock of the wind turbine and relieving the weight of the rotor

6.2 Disassembly of add-on parts of the housing 5

6.3 Turning the stationary bearing ring 7 about the axis of rotation 13 in the housing using a turning device

6.4 Assembly of the add-on parts of the housing 5

6.5 Rotor weight loading, rotor lock removal

6.6 Further operation of the wind turbine (rotation of the rotor)

Setting the rotor lock in step 6.1 prevents the rotor from rotating. In principle, this is possible in all the examples described above.

A start signal for carrying out the measures is preferably given by a condition monitoring system, specifically vibration monitoring. Reference List

1 main bearing assembly

2 rows of bearings

3 rotor shaft

4 wind turbine

5 housing

6 base frames

7 stationary bearing ring

8 to running bearing ring

9 rolling elements

10 main camps

11 rotors

12

13 axis of rotation

14 bearing ring segments

15 split stationary bearing ring

16

17

18 rotor hub

Claims

Claims Method for extending the service life of a main bearing arrangement (1) of a wind turbine (4), with at least one main bearing (10) with an axis of rotation (13) with at least one bearing row (2), in which a rotor shaft (3) of the wind turbine (4) is mounted , wherein the main bearing arrangement (1) has at least one stationary bearing ring (7), a rotating bearing ring (8) and rolling elements (9), characterized in that the stationary bearing ring (7) is rotated about the axis of rotation (13) of the main bearing arrangement (1). will. Method for extending the service life of a main bearing arrangement (1) of a wind turbine (4), with at least one main bearing (10) with an axis of rotation (13) with at least one row of bearings (2), in which a rotor shaft (3) of the wind turbine (4) is mounted and with a stationary housing (5) which is attached to a base frame (6) of the wind turbine (4), the main bearing arrangement (1) having at least one stationary bearing ring (7), a rotating bearing ring (8) and rolling elements (9). , characterized in that a new stationary bearing ring (7) is preferably installed with at least two bearing ring segments (14) instead of the previous damaged outer ring (7). Method according to Claim 1, in which the stationary bearing ring (7) is rotated by at least 45°, more preferably by at least 90° and preferably in an angular range of 160° to 200°, especially by 180°. The method of claim 2, wherein the

- rotating bearing ring (8) and/or

- a cage and/ or

- all or part of the rolling bearings (9) are not replaced. Method according to one of the preceding claims, in which the rotor shaft (3) is held by a fixture during rotation or replacement and is in particular made at least partially load-free, the fixture in particular being attached to a structural component such as a base frame (6) and/or rotor hub ( 18) is attached. Method according to one of the preceding claims, in which, in the case of a multi-row bearing with a plurality of axial bearing rings (7) adjoining one another in the direction of the axis of rotation (13), only some of these axial bearing rings (7) are rotated or exchanged. Method according to one of the preceding claims, in which the existing housing (5) is replaced by a split housing consisting of at least two housing segments. Method according to one of the preceding claims, wherein the installation situation of the stationary bearing ring (7) and the rotating bearing ring (8) is designed such that the rotating bearing ring (8) is an outer ring and the rotor shaft (3) does not rotate during operation. Method according to one of the preceding claims, characterized in that condition monitoring, eg vibration monitoring of the main bearing arrangement (1), is provided, the time at which the measures to extend the service life are carried out being determined as a function of the results of the condition monitoring. Method according to one of the preceding claims and according to claim 2, characterized in that the bearing ring segments (14) are shaped in such a way that a desired bearing play can be set. Method according to one of the preceding claims and according to claim 7, characterized in that the housing segments are shaped in such a way that a bearing clearance can be set.

12. The method according to any one of the preceding claims, wherein the stationary outer ring (7) is rotated in the housing (5). 13. The method according to any one of the preceding claims, wherein a rotating device is provided for rotating the stationary bearing ring.

14. The method as claimed in one of the preceding claims, in which components are heated in order to rotate the stationary bearing ring.

15. The method as claimed in one of the preceding claims, in which the main bearing arrangement (1) is a three-point bearing or a torque bearing.