Unlocking the wind turbine rotor

Abstract

A method for assisting unlocking, in particular a method for assisting unlocking the rotor of a wind turbine (1570) locked by a locking system (1575), wherein the rotor is coupled to an electromechanism (1571) and rotatably supported by rotor bearings, the method comprising the steps of: providing a torque reference (100, 200, 300, 700, 1100) or an equivalent current reference (1300); controlling the electromechanism (1571) based on the torque reference (100); and using the electromechanism to generate a mechanical torque acting on the rotor according to the torque reference, wherein the torque reference (100) defines a time course (t1, t2) of a target torque (tt1, tt2).

Description

Technical Field

[0001] The present invention relates to a method and a configuration for assisting unlocking, particularly to a method and a configuration for assisting unlocking of a rotor of a wind turbine locked by a locking system. The present invention further relates to a wind turbine provided with this configuration.

[0002] Background Art During the service or maintenance of a wind turbine, it may be necessary to lock the rotor of the wind turbine to prevent the rotor from accidentally moving by using a locking pin inserted between the rotor (or a brake disk rotating with the rotor) and the stator. In the case of a turbine having a roller bearing or a ball bearing for supporting the rotor, the locking pin may usually be loosened by moving the rotor by yawing and then pulling out the pin by a hydraulic mechanism or an electric mechanism.

[0003] However, in the case of certain types of bearings such as fluid film bearings (FFB bearings), the friction may become very high after a long stationary time, and the rotor may become fixed by being pressed against the surface of the brake disk hole, and it may be impossible to remove the locking pin even by using a hydraulic mechanism or an electric mechanism. In the case of a certain type of rotor bearing, when the rotor is locked for a relatively long period, the rotor bearing friction may become relatively high, and the rotor may not move by applying the conventional yawing (and blade pitching) method.

[0004] Due to the stick-slip effect of the bearing load, the conventional closed-loop position control method may not be easily applicable to the movement of the rotor. Therefore, the conventional methods of pulling out the locking pin and unlocking may be insufficient.

[0005] Therefore, there may be a need for a method and corresponding configuration to assist in unlocking, in particular, the unlocking of a rotor of a wind turbine locked by a locking system, such that reliable and safe unlocking of the rotor locked by the locking system is achieved without exposing the components of the wind turbine to the risk of damage.

[0006] Summary of the Invention This need can be satisfied by the invention described in the independent claim. Advantageous embodiments of the present invention are described in the dependent claims.

[0007] According to one embodiment of the present invention, a method is provided to assist in unlocking, in particular, the unlocking of a rotor of a wind turbine that is locked by a locking system (e.g., relative to a stator), wherein the rotor is coupled to an electromechanical device (e.g., a generator system) (e.g., a wind turbine) and is rotatably supported (e.g., relative to a stator) by rotor bearings, and the method includes the steps of providing (e.g., accessing or generating) a torque reference, controlling the electromechanical device based on the torque reference, and having the electromechanical device generate a mechanical torque that acts on the rotor according to the torque reference, wherein the torque reference defines the time course of a target torque.

[0008] At the start of application of this method, the rotor may be locked by a locking system to, for example, a stator or a stationary part of an electromachine. This allows the rotor to remain stationary and to be mechanically fixed (by the locking system) to a stationary part of the stator or electromachine.

[0009] The locking system may comprise one or more mechanical locking elements, such as bolts and / or pins. The locking system may comprise one or more openings or through holes or bores (in the stationary part and / or rotor), and may further comprise through openings or bores (in the stationary part and / or rotor). The locking system may further comprise several locking members that can be inserted into one or more locking holes in the stationary part and rotor part. To lock the rotor to the stationary part, each locking hole (one in the rotor and the other in the stationary part) may need to be aligned to substantially coincide with or overlap each locking opening. One or more locking members may then be inserted into both the locking hole in the stator shaft and the aligned locking hole in the rotor part for locking. When locked, the locking members, in particular the locking pins i.e., locking pins or bolts, may move slightly within the locking hole due to torque or force acting on, for example, the rotor and / or mounted rotor blades, and be pressed against one limiting surface area of ​​each locking hole.

[0010] When locked, the rotor may have one or more wind turbine blades attached. According to the embodiment, one or more wind turbine blades may be missing, for example, for replacement or assembly / disassembly work.

[0011] This method may be performed during the assembly / disassembly of a wind turbine, particularly while one or more rotor blades are attached to the rotor, or during any maintenance work, where it may be necessary to (temporarily) secure the rotor to a stationary part of the generator for any type of repair or maintenance work.

[0012] An electromachine may be designed to operate primarily in generator mode, generating or producing electrical energy as the rotor rotates by wind striking rotor blades mounted on the rotor. The electromachine may be configured, for example, as a synchronous electromachine, particularly a permanent magnet synchronous electromachine. The electromachine can provide multiple electrical phases, such as three electrical phases. The electromachine may have a multiphase electrical winding set for each of one or potentially multiple stator segments. Each or one or more of the winding sets may be connected to one or more converters.

[0013] A rotor bearing may be configured to rotatably support a rotor relative to a stationary part of a generator, particularly a stator in an electromachine.

[0014] A torque criterion can define multiple target torque values ​​for multiple subsequent points in time. The torque criterion may be defined or represented, for example, as an electronic data structure stored in an electronic memory device. Providing a torque criterion may involve accessing electronic data from the electronic memory device. In other embodiments, the torque criterion may be calculated (online).

[0015] The torque criterion (which can also be considered as the target torque time) may be pre-calculated or predetermined based on the wind turbine configuration, in particular adhering to or considering the mechanical configuration of the rotor, including one or more mounted wind turbine blades, and further considering the friction characteristics of the rotor bearings, and especially taking into account the rotor bearing stop time, i.e., the time the rotor was locked.

[0016] Therefore, the specific torque criteria used in this method may be dynamically selected based on specific state information and / or one or more operating parameters of the wind turbine, particularly the state of the rotor bearings and / or the mechanical state of the entire drivetrain, which includes the rotor, rotor blades, potential gearbox, and other components affecting the mechanical configuration of the drivetrain. In particular, the azimuth position of the rotor may also be taken into consideration.

[0017] Multiple torque reference instances may be referenced, for example, by one or more operating or state parameters, and may be retrieved, for example, using a lookup table.

[0018] Controlling an electromachine based on a torque criterion may, in particular, involve supplying control signals to the electromachine via a control module and / or converter. The converter may comprise multiple controllable switches, such as power transistors including IGBTs with individual gates, to which gate control signals may be supplied from the control module. The controllable switches may be controlled by their respective gate driver signals so that the electromachine generates mechanical torque according to a given torque criterion. This allows the electromachine to generate mechanical torque over multiple time points, in particular, in accordance with the torque criterion, i.e., in accordance with target torques at multiple time points.

[0019] When an electromachine is controlled according to a torque criterion (especially instead of controlling the rotor position), situations such as a rotor bearing seizing up, for example, due to a long period of inactivity, and then suddenly releasing from seizing with a sudden decrease in friction, can be addressed in an improved manner.

[0020] This method may or may not require an input indicating the rotor position. In particular, turbines with fluid membrane bearings as rotor bearings can be addressed using this method.

[0021] According to one embodiment of the present invention, the method includes the step of performing open-loop control based on a torque criterion, and / or the method is not based on a target rotor position, and / or the torque criterion is generated such that the target torque acts in a direction that releases the pressing force acting on the locking system, in particular in a direction that moves at least one locking pin away from the edge of the locking hole.

[0022] The torque generated by the electromechanical unit does not need to be measured, nor does it need to be fed back to the control unit for performing this method. Therefore, open-loop control may only involve supplying a torque reference to, for example, a further control unit and / or an electromechanical unit or electromechanical system including a converter or several converters.

[0023] The torque criterion may also include a definition of a torque upper limit (for example, limiting the absolute value of the target torque to be below the torque upper limit). In other embodiments, the torque upper limit may be a different quantity from the torque criterion. Nevertheless, the torque criterion may remain such that all values ​​of the target torque are below the torque upper limit.

[0024] The method assisting in unlocking may or may not depend on the target rotor position as an input. In other embodiments, the method may require the target rotor position as an input, for example, to adjust the electromechanical control for generating torque, particularly to stop it, when it is detected that the rotor has actually started moving or has moved by an amount greater than the threshold rotor momentum.

[0025] While locked, i.e., while the rotor is stopped, one or more components of the locking system can be positioned or moved such that the locking element presses against a particular lock hole edge. This lock hole edge may be a single edge that is contacted or pressed by any mechanical torque or force acting on the entire drivetrain and exerting any torque or force on the rotor.

[0026] The torque reference may be generated to act in a direction opposite to the mechanical torque or force applied to the rotor. Thereby, when the rotor is locked and stationary, the applied torque can be reduced, or the locking pin can be slightly separated from the edge of the locking hole where the locking pin is installed. The locking may still be possible by the remaining locking members, particularly the still-existing inserted locking pins that are still inserted into their respective locking holes, thereby still locking the rotor with respect to the stationary part of the electromechanical device. Nevertheless, by acting in a direction to release the pressing force on the locking system, it can be simplified to pull out the locking members, or particularly the locking pins, from their respective locking holes.

[0027] The direction in which the torque reference acts (e.g., acting clockwise or counterclockwise) can be automatically identified or set by, for example, maintenance personnel observing and / or inspecting the locking pin method or locking state, particularly how each locking member occupies its respective locking hole.

[0028] In other embodiments, the direction may be automatically determined, for example, from analyzing the mechanical configuration of the drive train.

[0029] According to one embodiment of the present invention, the torque reference includes an increasing magnitude (or absolute value) of the target torque in a first time period.

[0030] Torque can have a positive or negative sign, and the magnitude of the torque may be considered as the absolute value of the torque.

[0031] The magnitude of the target torque may increase linearly with time, or may increase according to a curved section or a plurality of curved sections corresponding to a plurality of linear sections with different slopes according to time. This can provide great flexibility. When the friction caused by the bearing is not known exactly from the beginning, it may be particularly advantageous to increase the magnitude of the target torque. This method may particularly include observing when the rotor starts to move or rotate.

[0032] According to one embodiment of the present invention, the torque reference includes that the magnitude of the target torque remains below the torque upper limit. In particular, the torque upper limit is based on at least one of the following, namely, the type and / or configuration and / or state of the rotor bearing, the rotor bearing stop time zone, the azimuthal position of the rotor, the gravitational torque acting on the rotor considering the gravity of one or more attached rotor blades, the aerodynamic torque acting on the rotor, and is estimated and / or calculated and / or predicted.

[0033] The torque upper limit may be determined such that when the electromechanical device actually generates a torque of a magnitude not exceeding the torque upper limit, it is predicted whether the rotor will move or not. The torque upper limit can be determined or estimated so as to substantially balance the mechanical torque acting on the drive train, or particularly on the rotor. When the torque generated by the electromechanical device balances the mechanical torque applied to the rotor due to the mechanical mass to which the rotor is connected (i.e., there is an opposite and approximately the same magnitude), it may be easier to release the members of the locking system.

[0034] In other embodiments, the torque upper limit can be determined or estimated so as to substantially exceed the mechanical torque acting on the drive train, or particularly on the rotor, in order to move the rotor or apply a short stroke.

[0035] Embodiments of the present invention provide a method for assisting unlocking without rotor movement, which will be described in detail below.

[0036] According to one embodiment of the present invention, the torque criterion includes increasing the target torque up to the torque upper limit without moving the rotor.

[0037] Torque generated by the electromechanical system acts on the rotor, and when the torque limit is reached, the torque acting on the rotor can be balanced, particularly by the mechanical configuration and condition of the rotor, including the rotor blades. If the rotor is not moving, safety may be improved.

[0038] According to one embodiment of the present invention, the torque criterion includes the condition that the target torque increases to a torque upper limit and then remains substantially constant, particularly in a second time period.

[0039] To maintain torque balance such that the resulting (net or total) torque acting on the rotor is substantially zero, it may be advantageous to keep the torque generated by the electromechanical system substantially constant at the torque upper limit.

[0040] Embodiments of the present invention provide a method for assisting unlocking, where the rotor moves by a specific amount. Furthermore, in these embodiments, the electromechanism is controlled based on a torque criterion. Again, in these embodiments, the position does not necessarily have to be a control variable. Nevertheless, the rotor position may be used, for example, as an input for detecting the motion of the rotor.

[0041] According to one embodiment of the present invention, the method further includes the step of detecting, at a first time point, when the rotor begins to move or rotate, and thus, in particular, when the target torque has a first torque value, wherein the torque criterion includes the target torque decreasing to a value less than the first torque value in a second time period after the first time point, in particular the first time point defines the end of the first time period and the beginning of the second time period.

[0042] The target torque generated by the electromechanical unit is greater (in strength) than the torque caused by gravity and / or friction acting on the rotor, allowing the rotor to begin moving or rotating. Therefore, reducing the target torque, or defining a torque criterion such that the target torque decreases after a first time point, can be advantageous in causing the rotor to move or rotate further. The target torque after the first time point can be reduced to substantially zero, or to any value greater than zero but less than the first torque value.

[0043] According to one embodiment of the present invention, the torque criterion includes the target torque being substantially zero during a first time point and / or a second time period. This simplifies the method.

[0044] According to one embodiment of the present invention, the method further includes at least one of the following: the torque criterion decreases in a second time period but remains above zero; and the torque criterion remains substantially constant above zero in a third time period following the second time period.

[0045] After the first time point, the target torque can be reduced in any way, for example, linearly or curvedly, following several curved sections or several straight sections.

[0046] According to one embodiment of the present invention, the electromachine can operate in generator mode or motor mode and / or is controlled by a machine controller, particularly by a converter and a converter controller. The electromachine can generate torque that acts on a rotor according to a torque criterion.

[0047] According to one embodiment of the present invention, the method further includes, in particular, at least one of the following steps: determining a rotor position indicator using at least one of at least one encoder, at least one Hall sensor, and at least one HFI sensorless observer; and / or determining the motion of the rotor based on the rotor position indicator; and / or applying electromechanical vector control.

[0048] At least one Hall sensor can detect a magnetic field or magnetic flux, particularly one resulting from a rotating rotor to which multiple permanent magnets are attached. From the observed or measured magnetic flux or magnetic field values, a processing section can determine the rotor position, for example, its electrical position.

[0049] An HFI sensorless observer can utilize high-frequency injection of current or voltage into a generator or electromachine. When high-frequency current or voltage is injected, the voltage or current measured in the electromachine may depend on the rotational electrical position of the rotor. The rotational position of the rotor can then be determined based on multiple current and / or voltage measurements and processing of the measurement results.

[0050] Vector control of an electromachine may involve converting electrical quantities, such as phase voltages and / or currents, in a static reference frame into quantities in a rotating coordinate system that rotates synchronously with the rotor of the electromachine. The rotating frame is sometimes called the dq frame. In practice, quantities in the static reference frame oscillating at the fundamental frequency may substantially be DC quantities in the synchronously rotating dq frame, thus simplifying the control.

[0051] According to one embodiment of the present invention, the method further includes the steps of unlocking the locking system in a second time period and / or applying the brakes to the rotor in a second time period, wherein unlocking the locking system includes pulling out a locking pin from a locking hole.

[0052] In the second time zone, each locking system may be in a released state where one or more locking pins are not pressed against the edge of their respective locking holes. Unlocking the locking system may involve pulling out one or more locking components, such as locking pins, from the locking holes. This also allows the use of certain unlocking tools, particularly hydraulic unlocking tools. The safety of this method may be improved if a rotor brake is applied.

[0053] According to one embodiment of the present invention, the rotor bearing includes or comprises at least one of a fluid membrane bearing, a roller bearing, and a ball bearing.

[0054] Features disclosed, described, or applied individually or in any combination to methods for assisting unlocking, particularly methods for assisting unlocking the rotor of a wind turbine, should be understood to be applicable individually or in any combination to each configuration for assisting rotor unlocking according to embodiments of the present invention, and vice versa.

[0055] According to one embodiment of the present invention, a configuration is provided for assisting unlocking, in particular for assisting unlocking a rotor of a wind turbine locked by a locking system, wherein the rotor is coupled to the electromechanism of the wind turbine and rotatably supported by rotor bearings, and the configuration comprises a torque reference module for providing a torque reference, an electromechanism and a mechanical controller connected and adapted to control the electromechanism to generate a mechanical torque acting on the rotor according to the torque reference, the torque reference defining the time course of a target torque, and the configuration particularly comprises an unlocking tool adapted to unlock the locking system.

[0056] This configuration may be configured to control or perform a method for assisting unlocking according to one embodiment of the present invention.

[0057] According to one embodiment of the present invention, a wind turbine is provided, the wind turbine including a rotor, a locking system adapted to lock the rotor (so that it does not rotate relative to a stator), a rotor bearing on which the rotor is rotatably supported (relative to a stator), and a configuration for assisting the unlocking of the rotor, in particular the unlocking according to the above embodiment.

[0058] The embodiments defined above and further embodiments of the present invention will become apparent from the examples of embodiments described below and will be explained with reference to these examples. The present invention will be described in more detail below with reference to these examples, but will not be limited thereto.

[0059] Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments shown or described. [Brief explanation of the drawing]

[0060] [Figure 1] This figure shows the reference torque applied according to one embodiment of the present invention. [Figure 2] This figure shows a reference torque applied according to another embodiment of the present invention. [Figure 3] This figure shows a reference torque applied according to yet another embodiment of the present invention. [Figure 4] This diagram schematically illustrates a functional diagram used in a method and configuration for assisting rotor unlocking according to one embodiment of the present invention. [Figure 5] This figure shows the load on the rotor bearing after different stopping times. [Figure 6] This figure shows the test results of applying a method for unlocking or assisting the unlocking of a rotor, including rotor motion, according to one embodiment of the present invention. [Figure 7] This figure shows the test results of applying a method for unlocking or assisting the unlocking of a rotor, including rotor motion, according to one embodiment of the present invention. [Figure 8]This figure shows the test results of applying a method for unlocking or assisting the unlocking of a rotor, including rotor motion, according to another embodiment of the present invention. [Figure 9] This figure shows the test results of applying a method for unlocking or assisting the unlocking of a rotor, including rotor motion, according to another embodiment of the present invention. [Figure 10] This figure shows the test results of a method for assisting rotor unlocking without rotor motion according to one embodiment of the present invention. [Figure 11] This figure shows the test results of a method for assisting rotor unlocking without rotor motion according to one embodiment of the present invention. [Figure 12] This figure shows a partial breakaway view of a wind turbine according to one embodiment of the present invention, including a configuration that assists in unlocking the rotor according to one embodiment of the present invention.

[0061] Modes for carrying out the invention The drawings are schematic. Note that in different drawings, elements that are similar or identical in structure and / or function are given the same reference numeral, or reference numerals that differ only in the first digit. Descriptions of elements not described in one embodiment can be obtained from the description of this element in relation to another embodiment.

[0062] Figure 1 schematically shows a torque reference 100 applied to a method for assisting the unlocking of a wind turbine rotor according to one embodiment of the present invention, in a coordinate system having a horizontal coordinate 101 representing time and a vertical coordinate 102 representing torque. According to this method, an electromachine is controlled based on the torque reference 100 to assist in unlocking a wind turbine rotor that is locked by a locking system (for example, relative to the stator of the electromachine).

[0063] Next, the electromechanical unit generates a mechanical torque acting on the rotor according to a torque reference 100. As can be seen from Figure 1, the torque reference 100 defines the time course of the target torque. For example, at time t1, the reference torque 100 defines the target torque tt1, and at time t2, the torque reference 100 defines the target torque tt2, which is greater than the target torque tt1. The torque reference 100 includes a target torque that increases over a first time period 103 from time t0 to time t3. This increase is, in the illustrated embodiment, a linear increase in the target torque over time.

[0064] The torque reference 100 is limited by the torque upper limit 104. Therefore, the target torque is always below the torque upper limit 104, or at most it remains above it. The horizontal line indicated by symbol 105 represents the gravitational load acting on the rotor. The torque upper limit is greater than the gravitational load 105.

[0065] Section 106 indicates the margin of error allowed for the generator torque having a specific rotor bearing (e.g., FFB) installed in a wind turbine. The target torque, defined by the reference torque 100, is equal to the torque upper limit 104 for time greater than t3.

[0066] From time t4 onward, the locking system that locks the rotor can be unlocked, in particular, within a second time period 107 beginning from time t3 when the target torque reaches the torque upper limit 104. Applying the method to unlock the rotor allows the target torque to rise to the torque upper limit 104 without moving the rotor.

[0067] Furthermore, as can be seen from Figure 1, the target torque increases up to the torque upper limit 104, and then remains substantially constant, particularly in the second time period 107.

[0068] The torque reference 100 shown in Figure 1 (which defines the time course of the target torque) can also be called a rotor-free unlocking method to which the balance torque is applied. Therefore, the lock pin can be pulled out without separating the pin from the edge of the lock hole, provided that the pressing force on the lock pin can be substantially reduced. In an unbalanced rotor, there is a gravitational load depending on the horizontal line 105. For example, the stiction of the bearings that lock the rotor can be estimated based on the rotor's stopping time. For example, the blade gravitational load on an unbalanced rotor can be estimated based on the rotor's mechanical position (azimuth angle). These estimates may be used as the value of the generator torque limit 104. Increasing the generator torque toward this limit 104 can reduce the pressing force on the lock pin. If the estimation of the torque limit 104 is correct, the effect of the pressing load is completely eliminated. However, a level of error 106 in the load estimation can be acceptable. First, the lock pin can be pulled out even if a small pressing force remains on it. Furthermore, in the case of force feedback (FFB), the bearing stiction resists the rotor motion, so the possible high stiction allows for greater errors in gravity load estimation. When applying a reference torque of 100 as shown in Figure 1, monitoring the rotor motion is not necessary or required, thus simplifying the method. One distinctive advantage is that low-resolution Hall effect sensors can be applied reliably because they can be used solely for generator torque control, and there is no need to observe changes in the state of the Hall effect sensors with respect to the rotor motion. In this case, torque generation capability may be reduced by approximately 14%, although in angle adjustment methods (not part of this invention), torque generation can reach 100%.

[0069] Figures 2 and 3 also show coordinate diagrams having horizontal coordinates 201 and 301 indicating time, vertical coordinates 202 and 302 indicating torque, and torque references 200 and 300 applied in a method for assisting the unlocking of a wind turbine rotor according to embodiments of the present invention. The torque references 200 and 300 shown in Figures 2 and 3 also define the time course of a target torque to be generated by the electromechanical, in particular, generator system of the wind turbine in order to enable or assist in the unlocking of the rotor from a situation in which the rotor is locked by the locking system.

[0070] However, according to the embodiments shown in Figures 2 and 3, the rotor may move at least slightly when the reference torque is set. As shown in Figures 2 and 3, the respective reference torques 200 and 300 include a target torque that increases in the first time period 203. This increase is linear with respect to time. According to other embodiments, the increasing target torque may increase, for example, according to one or more curved sections and / or one or more straight sections having different inclines.

[0071] At time t5, the motion of the rotor can be detected. Time t5 can be considered as the first time point. At the first time point t5, the target torque has a value tt5, which is the first torque value. After the first time point t5, the torque criterion defines that the target torque decreases, particularly at the second time intervals 207 and 307, respectively. The target torque decreases to a value smaller than the first torque value tt5.

[0072] In the example shown in Figure 2, the torque reference is reduced to virtually zero at the first time point t5. At the second time interval 207, the brake may be applied and / or the locking pin may be released to unlock the rotor.

[0073] In the example shown in Figure 3, the torque criterion is defined as the target torque decreasing in the second time period 307, but remaining above zero. As can be seen from Figure 3, the target torque decreases from the first torque value tt5 at the first time point t5 to a value greater than zero, 310.

[0074] In the third time interval 311, the target torque remains constant at the value 310 reached at the end of the second time interval 307. After the first time point t5, or within the second and / or third time intervals 307, 311, the brakes may be applied, and / or the locking system may be unlocked to unlock the rotor. Note that the reference torques 200 and 300 shown in Figures 2 and 3 are always below the torque upper limits 204 and 304, respectively.

[0075] According to the torque references 200 and 300 shown in Figures 2 and 3, short stroke (push) of the rotor by torque control may be applied. Tests have shown that the FFB load does not change much with small positional motion of the rotor. This property of the locking load can be used for lock pin release control. Essentially, the rotor may be pushed a short distance, and then, by removing the moving force, the rotor will remain in the position where it stopped.

[0076] After approximately 20 hours of downtime, measurements have shown that FFB stiction can be around 70% of its maximum value, provided the bearings are completely dry. After some slight fore-and-aft movement of the rotor within the locking hole, the rotor was started, and the bearing release torque was measured at a similar level to that previously observed. This suggests that the bearing stiction hardly changes with small rotor movements. Given the sticking characteristics of the FFB bearing load, it is possible to apply a generator torque higher than the bearing stiction to move or rotate the rotor at least slightly. Once the rotor has moved the desired distance, the generator torque may be cut off or at least reduced. Due to the high bearing sticking, the rotor will stop virtually immediately, and the rotor position will remain unchanged. This simplifies the work, as it does not require moving the rotor to the center of the locking hole, as only the locking pin needs to be loosened.

[0077] Because FFB stiction can change due to several factors such as stopping time and bearing temperature, the generator torque may increase until the rotor is observed to be moving or starting to move. The torque may then be cut (for example, at the first time point t5 in Figure 2 or Figure 3) or at least reduced as shown in Figure 3.

[0078] For example, if some gravitational load exists under an unbalanced rotor condition, such as when a single-blade mounting is applied, the generator torque may be maintained during rotor pin extraction (see, for example, Figure 3). This allows the generator torque to increase slowly, limiting the acceleration torque. If the rotor has moved or rotated slightly by a desired distance, the generator torque may be maintained, and turbine braking may be applied simultaneously. Thus, the rotor is kept stationary by balancing the torque from the generator, bearing stiction, gravitational load, and wind aerodynamic load. In practice, as shown in Figure 3, the generator torque can be reduced to a positive level within the braking torque capacity to save some current and / or to prevent the rotor from moving more than strictly required. This scheme can also be based on the view that, for lock pin extraction, the pin does not need to be at the dead center of the lock hole, i.e., there is room for small deviations and positions, or the rotor does not need to be completely stationary when braking.

[0079] In Figure 2, the torque cut at the first time point t5 does not need to be considered in terms of gravity load. In contrast, in Figure 3, according to the reference torque of 300, the torque decrease after the first time point t5 does not become zero, but becomes a positive torque value to counteract the potentially present gravity load. Whether to apply either the example shown in Figure 2 or the example shown in Figure 3 may depend on the gravity load, in particular the rotor's azimuth position, and whether all rotor blades are mounted or only some rotor blades are mounted.

[0080] Figure 4 shows a functional scheme for implementing a method for unlocking the rotor, for example, as shown in Figures 1, 2, or 3, where the respective reference torques are indicated. Figure 4 shows a functional diagram of a configuration 450 for assisting in unlocking the rotor of a wind turbine according to one embodiment of the present invention. Functional diagram 4 or configuration 450 may be configured to apply a torque reference as shown by curves 200, 300, and 100 in Figures 1, 2, or 3.

[0081] Configuration 450 comprises a torque reference module 451 for providing a torque reference 400. The torque reference may be similar to, or equal to, torque references 100, 200, or 300, for example, shown in Figures 1, 2, and 3. Configuration 450 further comprises an electric drivetrain (including an electromechanical unit) 452 and a mechanical controller 460 comprising several functional blocks. The mechanical controller 460 is connected and adapted to control the electromechanical unit 452 to generate mechanical torque acting on the rotor according to the torque reference 400.

[0082] In the illustrated embodiment of configuration 450, the configuration comprises a lock pin release control block 453 that receives a torque reference 400, a torque upper limit 404, and a rotor position 454. Furthermore, module 453 receives a rotor azimuth position 455 as an alternative to 454 in order to detect rotor motion. The rotor position 454 represents the electric rotor position, which is typically obtained from an HFI observer and a set of encoders or Hall effect sensors, while the azimuth position 455 represents the mechanical rotor position, which is typically measured from a turbine controller.

[0083] Based on the input signal, the lock pin release module 453 determines a torque request 456 to be supplied to the conversion module 457. The conversion module calculates a corresponding current request 458 to be supplied to the vector control module 459. The vector control module also receives the electric rotor position 454 to perform conversions to and from the dq rotation reference coordinate system. The vector control module 459 outputs a voltage request 461 to be supplied to the electromachine 452.

[0084] The electromachine 452 may be considered to comprise an entire drivetrain, including a generator and converter, and further including bearings and an inertia system. Bearing loads 462, gravity loads 463, and braking torques 464 act on the generator system or electromachine 452. Measuring sensors 465, including, for example, encoders and / or Hall sensors and / or sensorless HFIs, determine the electrical position 454 of the electromachine 452.

[0085] Figure 4 should be understood to provide a functional diagram 450 of a configuration to assist in unlocking. The illustrated functions may be provided by modules other than those illustrated. The entire configuration 450 may be considered to implement converter control.

[0086] For lock pin release, a torque reference 400 may be issued, for example, from the turbine controller. This torque reference typically appears as a time-based slope signal. Upon receiving this torque reference, the converter control unit 450 can convert it into a generator torque generating current 458, i.e., a generator Iq current controlled by standard vector control. The torque or current reference may also be derived from, for example, an internal controller of the converter control unit or a signal generator. The rotor electrical angle required for vector control 459 can be provided from a variety of options, such as an HFI sensorless observer, a Hall effect sensor, or an encoder. A key part of this technique may be torque control for lock pin release control. When it is identified that the rotor has moved a desired distance at a certain angle (for example, applicable to torque references 200, 300 shown in Figures 2 and 3), the torque reference may be terminated, held, or gradually reduced, and with the assistance of bearing stiction and / or brake torque, the rotor stops moving. At or after this point, the lock pin can be pulled out to complete the lock pin release.

[0087] Detection of rotor motion in module 465 of Figure 4 within the lock hole can be supported by various sources, such as rotor azimuth, HFI sensorless observer, Hall effect sensor, or encoder. The HFI (High Frequency Injection) sensorless observer may provide the best solution for both generator vector control and lock pin release control. Encoders may be permanently installed on the turbine or used as a portable kit when lock pin release is performed. Hall effect sensors may be of analog or digital type. The former can derive the generator position with high resolution for generator control and lock pin release control. The latter provides a robust and low-cost solution for torque control, but the angular resolution may be too coarse for lock pin release control.

[0088] In the alternative technique, namely the method shown in Figure 1 which uses balance generator torque, detection of rotor movement is not required, and a Hall effect sensor can be reliably applied for lock pin release.

[0089] Therefore, according to this embodiment, a torque criterion may be applied to release the pressing force between the lock pin and the hole without intending to move the rotor (without actually moving the rotor). This method simplifies the unlocking of the lock pin and may not require high resolution and high dynamic position feedback.

[0090] The conversion from torque requirements to generator Iq current (rms) can be formulated as follows:

number

[0091] Thus, p is the number of pole pairs of the machine, ψ is the air gap flux coupling of the machine from the permanent magnet, and γ is a coefficient that depends on the position feedback for vector control. For example, in the case of an HFI observer, γ=1, and when a digital Hall effect sensor is used, γ=cos(30°)~1 depending on the rotor electrical position within the sensor measurement range of 60 electric degrees.

[0092] Figure 5 shows the loads generated by the rotor bearings, particularly the force feedback bearing (FFB), where the horizontal coordinate 80 represents the angular motion of the rotor and the vertical coordinate 81 represents the bearing loads. Curves 82, 83, and 84 show the loads after 1 hour, 24 hours, and 7 days of standing still, respectively. The longer the standing time, the higher the static friction of the bearings. When small angular motions are performed, the bearing friction decreases sharply. Conventionally, position control has been difficult. For example, when a conventional position controller attempts to move the rotor, high mechanical torque (or current) is required to overcome the high stiction of the bearings. Therefore, conventional controllers require a high bandwidth to avoid overshoot during position control. Otherwise, the controller must move the rotor backward, and the torque required to overcome the bearing stiction changes sign. This stick-slip load adds a challenge to position control, and further problems are expected with conventional positioning control methodologies. Embodiments of the present invention can address the characteristics of bearing loads as shown in Figure 5 by controlling the unlock procedure based on a torque criterion, as described below and above.

[0093] Figures 6 and 7 show a coordinate system in which the horizontal coordinates 701 and 801 represent time, and the vertical coordinates 702 and 841 represent torque and electrical angle, respectively, schematically illustrating the time course of the torque reference 700 and electrical angles 843a, b, and c (derived by an HFI, encoder, or Hall sensor, respectively).

[0094] At a first time point t5, the encoder observes that the rotor is moving or has begun to move. At this first time point, the torque reference 700 decreases to zero, or the target torque decreases to zero. If rotor motion is not detected at the first time point t5, the target torque follows the course defined by the torque reference 700, represented by the solid line. However, with the start of rotor motion, the target torque decreases to zero at the first time point t5.

[0095] Figures 8 and 9 schematically show the time course of torque reference 1100 and electrical angles 1143a, b, and c (derived by HFI, encoder, or Hall sensor, respectively) in a coordinate system where the horizontal coordinates 1001 and 1101 represent time, and the vertical coordinates 1002 and 1141 represent torque and electrical angle, respectively.

[0096] At the first time point t5, the HFI observer detects that the rotor has started moving. Therefore, at this first time point t5, the torque is cut, i.e., the target torque is set to zero. During the second time point 1007, the lock pin may be released or removed and / or the brake may be applied.

[0097] In the test results shown in Figures 6 and 7, the encoder is used for vector control, and the azimuth position is used for detecting rotor motion and torque management for releasing the lock pin. When a tilt torque of 700 is applied and the level is sufficient to break the bearing stiction, causing a rotor motion of approximately 0.3°, the generator torque is cut.

[0098] In the test shown in the figure, as shown in Figures 8 and 9, HFI position feedback is used for mechanical vector control and torque management of lock pin release. The rotor moves approximately 0.14°, and therefore the lock pin release can be controlled well. Due to the presence of high friction in the bearing, the rotor remains in the stopped position, the lock pin loosens, and can be easily pulled out.

[0099] The torque reference 100 as shown in Figure 1 may be implemented by the functional scheme shown in Figure 4. A torque limit (see Figure 1, reference numeral 104) can be applied without using azimuth or mechanical / electrical angles in relation to the management of lock pin release, and the torque limit can be derived based on load estimation that takes into account bearing stiction and / or torque due to the gravity of the blades in the case of an unbalanced rotor. An advantage of this technique is that it is not necessary to monitor the precise rotor motion and, consequently, the rotor position, and therefore simple low-resolution position feedback such as a digital Hall effect sensor can be used.

[0100] The test results for this unlocking assistance without rotor motion are shown in Figures 10 and 11, which schematically show the time course of the current (reference) 1300' and electrical angles 1443a and 1443b (derived by the HFI and encoder, respectively) in a coordinate system where the horizontal coordinate is time and the vertical coordinates are current Iq and electrical angle 1302 and 1441, respectively. Curve 1443c represents the rotor speed and shows the motion of the rotor after the locking system has been unlocked.

[0101] It should be understood that torque can be proportional to the current amplitude, as shown in Figure 10. In this test, the turbine is fitted with a single blade, and the rotor is locked at a 60° position where the torque due to the blade's gravity is approximately 87% of its maximum value. Torque can be increased by closed-loop control to generate a balance torque, but the rotor does not move due to torque limits. Once a stable balance torque is generated, the rotor is no longer firmly fixed to the lock pin. At this point, the lock pin can be pulled out without force. Brake operation may also be applied, which provides some tolerance in the torque limit estimation without moving the rotor.

[0102] Embodiments of the present invention provide the following: - A simple lock pin release control technique that can be applied in the case of FFB bearings and / or high gravitational loads due to unbalanced rotors. - A method to reduce rotor angular motion by using short-pulse generator torque while utilizing high bearing stiction. - A method that uses balanced generator torque but does not use rotor motion, and does not require precise positional feedback for torque control. - Compared to rotor positioning solutions, this approach is less likely to excite blade and tower vibrations. - Implementations using position feedback from rotor azimuth angle, generator HFI sensorless observer, Hall effect sensor management, or encoder measurement.

[0103] The embodiment is also applicable to turbines having roller bearings or ball bearings.

[0104] Figure 12 schematically shows a portion of a wind turbine 1570 according to one embodiment of the present invention, including a configuration for assisting in the unlocking of the rotor according to one embodiment of the present invention. The wind turbine 1570 comprises a rotor (not shown) of a generator 1571. The generator 1571 comprises a stator 1572 including a multiphase winding set (not shown in detail). The rotor 1573 is rotatably supported relative to the stator 1572, but the rotor bearings are not shown in detail. A brake disc 1574 is mounted on the rotor 1573. Thus, during normal operation, the brake disc 1574 rotates relative to the stator 1572.

[0105] For maintenance purposes, the wind turbine 1570 is equipped with a locking system 1575. In the illustrated embodiment, the locking system is embodied by locking holes 1576 within the stator 1572 and the brake disc 1574. A locking pin 1577 may be inserted into the locking hole to lock the rotor 1573 against the stator 1572. A locking pin actuator 1578 is provided for inserting and withdrawing the locking pin 1577. To release or unlock the locking system 1575, a method for assisting the unlocking of the locking system according to one embodiment of the present invention can be performed.

[0106] Note that the term “comprising” does not exclude other elements or steps, and “a” or “an” does not exclude multiple elements. Also, elements described in relation to different embodiments may be combined. Note that reference numerals in the claims should not be construed as limiting the claims.

Claims

1. A method for assisting unlocking, in particular a method for assisting unlocking the rotor of a wind turbine (1570) that is locked by a locking system (1575), wherein the rotor is coupled to an electromechanical device (1571) and rotatably supported by rotor bearings, and the method is The steps include providing a torque reference (100, 200, 300, 700, 1100) or an equivalent current reference (1300) that represents the torque reference, A step of controlling the electric machine (1571) based on the torque or current reference (100), The steps include: generating a mechanical torque acting on the rotor according to the torque reference using the aforementioned electromachine; Includes, The torque reference (100) defines the time progression (t1, t2) of the target torque (tt1, tt2). method.

2. The steps include (100) performing open-loop control based on the torque criterion, and / or It is not based on closed-loop position control, and / or The torque reference (100) is generated such that the target torque acts in a direction that releases the pressing force acting on the locking system (1575), and in particular in a direction that moves at least one locking pin away from the edge of the locking hole. The method according to claim 1.

3. The method according to any one of claims 1 to 2, wherein the torque reference (100) includes the magnitude of the increase in the target torque in the first time period (103, 203, 303).

4. The torque criterion (100) includes the condition that the magnitude of the target torque remains below the torque upper limit (104, 204, 304), In particular, the torque upper limit is at least one of the following, namely, Rotor bearing type and / or configuration and / or condition, During the rotor bearing stopping time, The azimuth angle position of the rotor, Taking into account the gravity of one or more mounted rotor blades, the gravity-induced torque acting on the rotor, Aerodynamically generated torque acting on the rotor, Based on at least one of the following, the following is estimated and / or calculated and / or predicted: The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the torque reference (100) includes increasing the magnitude of the target torque up to the torque upper limit (104) without moving the rotor.

6. The method according to claim 5, wherein the torque reference (100) includes the magnitude of the target torque increasing up to the torque upper limit (104) and then remaining substantially constant, particularly in a second time period (107).

7. The process further includes detecting, at a first time point (t5), when the rotor begins to move or rotate, and thereby, in particular, when the target torque has a first torque value (tt5). The torque criterion includes the fact that the magnitude of the target torque decreases to an absolute value smaller than the first torque value, particularly during the second time period (207, 307) after the first time period (t5). In particular, the first time point (t5) defines the end of the first time period (203, 303) and the beginning of the second time period (207, 307). The method according to any one of claims 1 to 4.

8. The method according to claim 7, wherein the torque reference (200) includes the magnitude of the target torque decreasing to substantially zero at the first time point (t5) and / or remaining zero during the second time point (207).

9. The torque criterion (300) includes the condition that the magnitude of the target torque decreases during the second time period (307) but remains above zero, The torque criterion is that in the third time period (311) following the second time period (307), the magnitude of the target torque remains substantially constant above zero. Further including at least one of the following: The method according to any one of claims 7.

10. The method according to any one of claims 1 to 9, wherein the electric machine (1571) can operate in generator mode or motor mode and / or is controlled by a machine controller, in particular a converter and a converter controller.

11. especially, At least one encoder, At least one Hall sensor, At least one HFI observer, A step of determining the rotor position indicator amount using or employing at least one of the following: A step of determining the movement of the rotor based on the rotor position indication amount, A step of determining the movement of the rotor based on a measurement of the azimuth angle position of the rotor position, and / or A step of applying vector control to the aforementioned electromechanism, Further including, The method according to any one of claims 1 to 10.

12. The steps of unlocking the locking system (1575) during the second time period (107, 207, 307), and / or The step of applying the brakes to the rotor during the second time period is further included, Unlocking the aforementioned locking system includes pulling the locking pin out of the locking hole. The method according to any one of claims 1 to 11.

13. The rotor bearing is Fluid membrane bearings, Roller bearings, Ball bearings, The method according to any one of claims 1 to 12, comprising or including at least one of the following.

14. A configuration (450) for assisting unlocking, in particular a configuration (450) for assisting unlocking a rotor of a wind turbine locked by a locking system (1575), wherein the rotor is coupled to the electromechanical structure of the wind turbine and rotatably supported by rotor bearings, and the configuration (450) is A torque reference module (451) for providing a torque reference (400) or an equivalent current reference, The aforementioned electrical machinery (452, 1571) and, A mechanical controller connected to and adapted to control the electromachine in order to generate a mechanical torque acting on the rotor according to the torque standard, Equipped with, The torque reference (400) defines the time course of the target torque, The above configuration, in particular, A locking tool (1578) adapted to unlock the aforementioned locking system. Equipped with, Composition (450).

15. A wind turbine (1570), Rotor and, A locking system (1578) adapted to lock the rotor, The rotor is rotatably supported (relative to the stator) by a rotor bearing, A configuration (450) for assisting unlocking, in particular a configuration (450) for assisting unlocking the rotor as described in claim 14, A wind turbine (1570) equipped with this.

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