Armature and related methods for wind turbine generators

Abstract

To provide an armature for a power generator of a wind turbine, for example, a permanent magnet power generator, and a method for operating such armature, generator, and wind turbine.SOLUTION: The present disclosure relates to an armature for a wind turbine power generator. The power generator may be a permanent magnet power generator. The present disclosure further relates to a method for operating such armature, power generator, and wind turbine. The method can include steps of: partially short-circuiting an armature winding by closing a first switch; and inducing current to the armature winding by wind acting on a wind turbine blade.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to armatures for electromechanical machines. More particularly, the present disclosure relates to armatures for generators of wind turbines, such as permanent magnet generators, and methods for operating such armatures, generators, and wind turbines.

Background Art

[0002] Generally, modern wind turbines are used to supply electricity to the power grid. This type of wind turbine generally includes a tower and a rotor disposed on the tower. The rotor, typically including a hub and a plurality of blades, is adapted to rotate under the influence of wind on the blades. The rotation usually generates torque that is transmitted directly through the rotor shaft to the generator or using a gearbox. In this way, the generator generates electricity that can be supplied to the power grid.

[0003] The wind turbine hub may be rotatably coupled to the front of the nacelle. The wind turbine hub can be connected to the rotor shaft, which can then be rotatably mounted within the nacelle using one or more rotor shaft bearings disposed on a frame inside the nacelle. The nacelle is a housing disposed on top of the wind turbine tower. The nacelle can accommodate and protect additional components such as, for example, a gearbox (if present) and optionally a generator, as well as a power converter and auxiliary systems depending on the wind turbine.

[0004] The generator of a wind turbine can have a magnetic field generator and an armature, the magnetic field generator being configured to generate a magnetic field and the armature being configured to conduct a current induced in its windings by the influence of a varying magnetic field during rotation.

[0005] A generator may include insulators that can help increase its reliability and service life. These insulators can, for example, provide thermal and voltage spike protection. For example, the insulators may be placed between the coils of the generator's armature.

[0006] When a wind turbine generator stops for any reason, the generator's insulators can become wet or damp. For example, during a grid shutdown, the amount of humidity inside the generator may not be controlled, and condensation or moisture absorption may occur, especially if the wind turbine is an offshore wind turbine. Condensation inside the insulators can form a tracking surface to the ground, which can cause a ground fault if the insulators are not dried before the generator is restarted. Moisture absorption by the insulators can cause delamination due to vapor expansion, potentially leading to long-term degradation of the insulators. Also, water absorption can significantly reduce the dielectric properties of the insulators. This can result in electrical breakdown when the generator is initialized again without drying the insulators.

[0007] Therefore, avoiding humidity within the insulator is crucial for safely restarting a generator. In some cases, it may be necessary to dry the generator's insulator first. For example, manual inspections to check whether the insulator is suitable for restarting a generator are known to be performed on onshore wind turbines. This is a laborious task, and furthermore, similar inspections can be considerably more difficult on offshore wind turbines due to limited access. In such cases, a possible method to ensure that the insulator is dry and the generator can be safely restarted is to blow warm air through the armature for a specific period of time. Such a period could be, for example, 8 to 24 hours. This means that the operation of the wind turbine may need to be delayed until heating and drying are complete.

[0008] Another option might be to use the wind turbine's power converter at a low voltage to supply current to the generator windings, and thus heat the insulators above the dew point due to heat loss. However, this option is only possible if the power converter is present and fully operational, which may not be the case during installation or maintenance. In addition, it may be necessary to dry the insulators of the power converter before using it to dry the generator insulators. [Overview of the project]

[0009] One aspect of the present disclosure provides a method for operating a wind turbine. The wind turbine comprises a rotor including one or more wind turbine blades and a generator including an armature. The armature comprises three or more windings and is configured to provide three or more electrical phases. A first winding is configured to provide a first electrical phase, a second winding is configured to provide a second electrical phase, and the second and first electrical phases are out of phase. The method includes partially short-circuiting the armature windings by closing a first switch between the output wire of the first winding and the output wire of the second winding. The method further includes inducing a current in the armature windings by wind acting on the wind turbine blades.

[0010] In this embodiment, the presence of at least a first switch allows the armature to be partially short-circuited. Therefore, the generator insulator can be heated by the current induced in the partially short-circuited armature winding due to the movement of the wind turbine blades and the corresponding rotation of the generator rotor. In other words, the generator insulator can be dried without the need for a power converter.

[0011] In particular, a partial short circuit between two of the three electrical phases of the generator armature windings can reduce the current induced in the generator armature and, therefore, the torque that may be required to rotate the generator rotor. This may be particularly advantageous for permanent magnet generators, where the magnitude of the generated magnetic field cannot fluctuate and the current induced in the armature can depend on the wind flowing around the wind turbine blades and its velocity.

[0012] In addition, the time required to heat the generator insulator can be significantly reduced compared to when hot air is blown onto it by a generator cooling system. Such a time can be reduced, for example, to one or two hours.

[0013] Throughout this disclosure, it will be understood that a winding is a conductor, such as a wire, included in the armature of a generator. The winding may be wound, for example, around an armature tooth to form turns. A group of turns may be called a coil. In some examples, a coil may consist of only one turn. Thus, a winding may comprise one or more coils. For example, a winding may comprise three coils, each coil being wound around an armature tooth.

[0014] The winding may include an output wire. In this specification, it will be understood that the output wire is configured to carry the current induced in the winding directly, for example, toward a power converter in the case of a wind turbine, or toward a power grid. The output wire may be formed integrally with the corresponding winding; for example, the end of the winding may be an output wire, or it may be provided as a separate element connected to the winding.

[0015] A changing magnetic field, such as a rotating magnetic field caused by the rotation of a rotor containing permanent magnets, can induce an alternating voltage (and therefore an alternating current) in the armature windings. Throughout this disclosure, it will be understood that the electrical phase may also be an alternating voltage induced in the windings. Such a voltage may have a sinusoidal waveform. Thus, if the armature has, for example, three windings, each winding can provide an electrical phase in the presence of a changing magnetic field.

[0016] Therefore, any reference throughout this disclosure to a winding that provides an electrical phase may refer to the fact that an alternating voltage is induced in the winding (e.g., in one or more coils of the winding) by a fluctuating magnetic field.

[0017] Two electrical phases may have an electrical phase difference between them. In this specification, the electrical phase difference can be understood as the angular difference between two electrical phases. When the electrical phase difference between two electrical phases is zero, the two electrical phases are said to be in phase. When the electrical phase difference between two electrical phases is not zero (or is a multiple of 360°, i.e., n·360°, where n=1, 2, 3, ...), the two electrical phases are said to be out of phase. In a three-phase armature, i.e., an armature having three windings, each winding providing an electrical phase, the electrical phase difference between any two of the three electrical phases may be, for example, 120°.

[0018] Throughout this disclosure, a short circuit can be understood as providing a low-resistance electrical connection. For example, two windings can be short-circuited by electrically connecting them through a wire or switch, etc. Thus, after a short circuit, i.e., after a new electrical path has been formed, current can proceed through such an electrical path.

[0019] It will be understood that in this specification, a switch can refer to any electrical element that can electrically connect or disconnect a conductive path in an electrical circuit. A switch can selectively enable current to pass between wires to which the switch is connected (e.g., attached). A switch can provide one or more electrical connections through which current can proceed.

[0020] The terms "current" and "currents" can be used interchangeably throughout this disclosure.

Brief Description of the Drawings

[0021] [Figure 1] It is a perspective view of an example of a wind turbine. [Figure 2] It is a simplified internal view of an example of the nacelle of the wind turbine of FIG. 1. [Figure 3A] It is a diagram schematically showing an example of a generator armature. [Figure 3B] It is a diagram schematically representing an electrical phase output that can be provided by the armature of FIG. 3A according to an example. [Figure 4] It is a diagram showing an example of a short-circuit current that can be induced in the armature of FIG. 3A as a function of the rotor speed. [Figure 5] It is a diagram showing an example of the torque that may be required to achieve the rotational speed and induced current of the example of FIG. 4. [Figure 6] It is a diagram showing an example of the wind speed that may be required to reach the torque value of FIG. 5. [Figure 7] It is a flowchart of a method for operating a wind turbine. [Figure 8] It is a diagram schematically showing an example of a generator armature according to the present invention. <​​​​​​A diagram schematically showing the electrical phase output that can be provided by the armature of FIG. 10A according to one example. [Figure 11] A flowchart of a method for heating an insulator of a generator of a wind turbine. [Figure 12] A diagram showing an example of a short-circuit current that can circulate in the winding of the example of FIG. 10A as a function of the rotor rotation speed and comparing it with the short-circuit current of FIG. 4. [Figure 13] A diagram showing torque as a function of rotor speed that may be required to reach the current value shown in FIG. 12.

Embodiments for Carrying Out the Invention

[0022] Here, embodiments of the present invention will be referred to in detail, and one or more examples thereof are shown in the drawings. Each example is presented as an explanation of the present invention and is not intended to limit the present invention. In fact, it will be apparent to those skilled in the art that various modifications and changes can be made in the present invention without departing from the scope or spirit of the present invention. For example, features illustrated or described as part of one embodiment can be used in another embodiment to yield further embodiments. Accordingly, the present invention is intended to encompass such modifications and changes within the scope of the appended claims and their equivalents.

[0023] Examples of an armature module and an armature for a generator of a wind turbine are particularly shown, but the same armature module and armature can also be used in other electrical machines and / or other applications.

[0024] [[ID=2,4]] Figure 1 shows a perspective view of an example of a wind turbine 160. As shown, the wind turbine 160 includes a tower 170 extending from a support surface 150, a nacelle 161 mounted on the tower 170, and a rotor 115 coupled to the nacelle 161. The rotor 115 includes a rotatable hub 110 and at least one rotor blade 120 coupled to the hub 110 and extending outward from the hub 110. For example, in the illustrated embodiment, the rotor 115 includes three rotor blades 120. However, in alternative embodiments, the rotor 115 may include more or fewer rotor blades 120 than three. Each rotor blade 120 may be spaced around the hub 110 to facilitate the rotation of the rotor 115 and to allow kinetic energy from the wind to be converted into usable mechanical energy, and subsequently electrical energy. In some examples, the hub 110 may be rotatably coupled to a generator 162 (Figure 2) positioned within the nacelle 161, enabling the generation of electrical energy.

[0025] Figure 2 shows a simplified internal view of an example of the nacelle 161 of the wind turbine 160 of Figure 1. As illustrated in this example, the generator 162 may be located within the nacelle 161. Generally, the generator 162 may be coupled to the rotor 115 of the wind turbine 160 to generate electricity from the rotational energy generated by the rotor 115. For example, the rotor 115 may include a main rotor shaft 163 coupled to the hub 110 for rotation together with the hub 110. The generator 162 may then be coupled to the rotor shaft 163 so that the rotation of the rotor shaft 163 drives the generator 162. For example, in the illustrated embodiment, the generator 162 includes a generator shaft 166 rotatably coupled to the rotor shaft 163 through a gearbox 164.

[0026] In this example, the rotor shaft 163, gearbox 164, and generator 162 may be supported within the nacelle 161 by a support frame or bed plate 165 positioned at the top of the wind turbine tower 170.

[0027] The nacelle 161 may be rotatably coupled to the tower 170 by a yaw system 20 so that the nacelle 161 can rotate around the yaw axis YA. The yaw system 20 comprises a yaw bearing having two bearing components configured to rotate relative to one other. The tower 170 is coupled to one of the bearing components, and the bed plate or support frame 165 of the nacelle 161 is coupled to the other bearing component. The yaw system 20 comprises an annular gear 21, a plurality of yaw drive units 22 having motors 23, a gearbox 24, and a pinion 25 for meshing with the annular gear 21 to rotate one of the bearing components relative to the other.

[0028] In some other examples, the generator 162 may not be located within the nacelle 161. For example, the generator 162 may be located between the rotor 115 and the nacelle 161 in a direct-drive wind turbine.

[0029] The blade 120 is coupled to the hub 110 via a pitch bearing 100 between the blade 120 and the hub 110. The pitch bearing 100 comprises an inner ring and an outer ring. The wind turbine blade can be mounted on either the inner bearing ring or the outer bearing ring, and the hub is connected to the other. When the pitch system 107 is actuated, the blade 120 can perform rotational motion relative to the hub 110. Thus, the inner bearing ring can perform rotational motion relative to the outer bearing ring. The pitch system 107 in Figure 2 comprises a pinion 108 that meshes with an annular gear 109 provided on the inner bearing ring to rotate the wind turbine blade around the pitch axis PA.

[0030] For example, it may be necessary to dry the generator insulator in order to safely start the generator 162 after it has been stopped. Apparatus and methods suitable for this purpose are disclosed herein.

[0031] An example of an armature 300 that can be short-circuited as a whole, i.e., by providing an electrical connection between all of its armature windings, is shown in Figure 3A. In this example, the armature 300 is a three-phase armature (i.e., an armature configured to provide three electrical phases) and comprises three windings 310 connected in parallel. In other examples, the windings may be connected in series. Both of these situations should be considered as represented in Figure 3A.

[0032] Each winding 310 has an output wire 330. The current induced in the winding 310 may be conducted through the output wire 330 to a power converter if included in a wind turbine, or directly to the power grid. The armature 300 is connected in a star, Y-shaped, or Y-shaped configuration in this example.

[0033] Each winding 310 may be configured to provide three or more electrical phases 340. For example, as shown in Figure 3B, the first winding 311 may be configured to provide a first electrical phase 341, the second winding 312 may be configured to provide a second electrical phase 342, and the third winding 313 may be configured to provide a third electrical phase 343. Figure 3B schematically represents these electrical phases 340 and the electrical phase difference 350 between them.

[0034] In the example in Figure 3B, all electrical phases 340 have substantially the same electrical phase difference 350 between them. That is, the electrical phase difference 350 between each pair of electrical phases 340 is substantially the same. Therefore, the electrical phase difference 350 is 120° in Figure 3B.

[0035] In the absence of a separate drive device such as a converter, the generator rotor needs to rotate at a specific rotational speed by the action of the wind on the wind turbine blades 120 in order to reach a certain level of current in the armature winding 310. Similarly, in order to achieve a sufficient rotational speed, it is necessary to exceed a certain wind speed for a certain period of time. Figures 4 to 6 illustrate this with an example.

[0036] Figure 4 shows an exemplary example of the generation of a short-circuit current flowing through the armature winding 310 as a function of the rotor speed of a wind turbine, such as a wind turbine equipped with a permanent magnet generator, when the entire three-phase armature is short-circuited, as in Figure 3A, i.e., the three output wires 330 are placed on electrical contacts. The total short-circuit of winding 310 is shown as 370 in Figure 3. As shown in this figure, for a given magnetic field (determined by the permanent magnet configuration of the rotor), the higher the rotational speed of the rotor, the higher the induced current in the short-circuit winding can be.

[0037] In this specification, a short-circuit current may refer to a current induced in an armature winding that travels (at least) through an electrical path provided by one or more switches 320, a path not provided during the normal operation of the generator 162. Also, throughout this disclosure, a short circuit may refer to providing such a connection that enables an electrical path that was previously unavailable. For example, one or more electrical paths or connections can be provided by closing a switch.

[0038] Figure 5 shows an exemplary example of the torque that may be required to achieve the rotational speed and induced current in the example of Figure 4. Figure 5 shows that torque can increase rapidly with rotational speed, and that generally, high torque values ​​of, for example, 0.4–0.6 pu (per unit value with respect to nominal torque as a reference value) can already be reached at very low rotational speeds of the rotor, for example, 0.1 or 0.2 rpm.

[0039] As shown in the example in Figure 6, fairly high wind velocities may be required to obtain the torque necessary to rotate the rotor at a speed sufficient to induce current in the short-circuited armature winding 310. For example, wind velocities of 7–9 m / s may be required to provide a torque of 0.4–0.6 pu. This means that, before starting the wind turbine, the general wind velocity must exceed this level for a sufficient period of time to induce current in the stator and heat the windings and surrounding insulation. This could mean that, at a given moment, the wind turbine may not be able to start safely, or that the start may need to be delayed by several hours, days, or even weeks.

[0040] However, partially short-circuiting the armature winding 310 may reduce the current induced in the winding 310 for a given rotational speed. Similarly, less torque, and therefore less wind speed, may be required to rotate the rotor at such a rotor speed. Consequently, the time required to start the wind turbine after an interruption may be reduced.

[0041] Through this disclosure, partial short-circuiting can refer to enabling one or more electrical paths between windings such that not all armature windings are placed in electrical contacts at the same time. In one example, an armature may include three windings and can be partially short-circuited by providing an electrical connection between two of the windings.

[0042] In another example, the armature may include six windings, for example, windings 1 through 6. The six windings can be thought of as three pairs of windings, for example, pair 1 containing windings 1 and 2, pair 2 containing windings 3 and 4, and pair 3 containing windings 5 ​​and 6. Such an armature may be partially short-circuited by providing three electrical connections, for example, one for each pair of windings, i.e., one between windings 1 and 2, one between windings 3 and 4, and one between windings 5 ​​and 6. Thus, while all windings can actually be short-circuited, the armature (or armature windings) can still be partially short-circuited and not completely short-circuited, as not all windings are placed on electrical contacts, as shown in Figure 3A.

[0043] Therefore, in one aspect of the present invention, a method 700 for operating a wind turbine, for example, the wind turbine 160 shown in Figure 1, can be provided. Figure 7 shows a flowchart of such a method. The wind turbine 160 comprises a rotor 115 including one or more wind turbine blades 120 and a generator 162 including an armature 300.

[0044] The armature 300 comprises three or more windings 310 and is configured to provide three or more electrical phases 340, wherein the first winding 311 is configured to provide a first electrical phase 341, and the second winding 312 is configured to provide a second electrical phase 342, and the second electrical phase 342 and the first electrical phase 341 are out of phase.

[0045] The method includes partially short-circuiting the armature winding 310 in block 710 by closing a first switch 321 between the output wire 331 of the first winding 311 and the output wire 332 of the second winding 312. That is, the first switch 321 provides an electrical connection between the output wire 331 of the first winding 311 and the output wire 332 of the second winding 312.

[0046] In some examples, the output wire 330 may be formed integrally with the corresponding winding 310. In other examples, the output wire 330 and the winding 310 may be provided as separate elements connected to each other, for example, physically connected.

[0047] An example of such an armature 300 can be seen in Figure 8. The armature in Figure 8 can correspond to the three-phase armature in Figure 3A, but the switch 320 is connected between output wires 331 and 332. Thus, in this figure, the switch 320 can enable electrical connection between wires 331 and 332, or rather, it can enable electrical connection between all three output wires 331, 332, and 333 as in Figure 3A.

[0048] The switch 320, for example, the first switch 321, may be any electrical element suitable for allowing current to pass between the wires to which the switch is connected (e.g., mounted).

[0049] The method further includes, in block 720, inducing an electric current in the armature winding 310 by the wind acting on the wind turbine blade 120.

[0050] By partially short-circuiting the armature 300 in this way, the generator insulator can be dried quickly and efficiently. This is due to the fact that the generator insulator can be heated without a power converter and without high airflow. In particular, the heating time can be reduced compared to, for example, when hot air is blown to dry the insulator. In some cases, a heating period of one or two hours may be sufficient before starting the generator 162. This method may be particularly advantageous for such generators, since the magnetic field induced in the stator winding 310 cannot fluctuate in a permanent magnet generator.

[0051] Therefore, instead of completely short-circuiting the windings 310 of the generator armature 300 as shown in Figure 3A, they can be partially short-circuited, for example, as shown in Figure 8.

[0052] In some examples, the method may further include providing one or more switches 320 and connecting the first switch 321 between the output wire 331 of the first armature winding 311 and the output wire 332 of the second armature winding 312.

[0053] As described above, the generator armature 300 can be configured to provide an electrical phase output in which all electrical phase differences 350 are substantially the same. However, in some other examples, the armature 300 may be configured to provide an electrical phase difference 355 between two of the electrical phases 340 that are lower than another electrical phase difference 350 of the armature.

[0054] In some of these examples, the armature may be configured to provide an electrical phase difference lower than any of the other electrical phase differences configured to be provided by the armature, as shown in the electrical phase output 360 in Figure 9. As seen in this figure, the two electrical phase differences between different windings are separate. In some other examples, there may be three or more different electrical phase differences between windings. The electrical phase difference 350 can be configured by adjusting the distance (with respect to azimuth angle) between the coils contained in winding 310 that provide a different electrical phase 340.

[0055] In some examples, the first electrical phase 341 and the second electrical phase 342 may have an electrical phase difference 355 that is lower than the electrical phase difference between any other electrical phases.

[0056] Depending on the number of electrical phases 340 and the value of the electrical phase difference 350, there may be multiple options for connecting the output wire 330 configured to provide a lower electrical phase difference than other or any other output wire 330.

[0057] For example, in Figure 9, there is a clearly identifiable lowest electrical phase difference 355 among the electrical phases 340. In this specification, “lowest” refers to the fact that the electrical phase difference 355 is lower than the other electrical phase differences 350. Thus, in some examples, the armature may be configured to provide the lowest electrical phase difference 355. This lowest electrical phase difference 355 may be, for example, 80°, while the other two electrical phase differences 350 may be, for example, 140°.

[0058] However, in another three-phase example, one electrical phase difference may be, for example, 180°, and the lowest electrical phase difference 355 may be, for example, 90°. That is, multiple lowest electrical phase differences 355 are possible. In this example, switch 320 can be connected between two output wires that provide any of the 90° electrical phase differences. Alternatively, switch 320 may be connected between three output wires 330, but at some point an electrical connection may be provided between one pair of wires that provide a 90° electrical phase difference 355, or between the other pair of wires that provide a 90° electrical phase difference 355.

[0059] A short circuit between the windings 310, configured to provide the lowest electrical phase difference 355, can again reduce the induced current when the rotor rotates due to the action of wind on the wind turbine blades 120. Thus, heating of the generator insulator can be carried out more efficiently, especially compared to the case where all output wires 330 of the generator winding 310 are short-circuited as shown in Figure 3A.

[0060] In some examples, as will be further explained below with respect to Figure 10A, three or more windings 310 may be arranged in winding groups 405, 410 consisting of, for example, three windings. In some of these examples, each group 405, 410 may be connected to its own neutral wire 380. In some other examples, each group 405, 410 may be connected to the same neutral wire 380, that is, instead of a number of neutral wires 380 equal to the number of winding groups 405, 410, there may be only one neutral wire 380.

[0061] In some examples, the armature may comprise two or more winding groups 405, 410, each group comprising its own neutral wire 380. In these examples, the method may further include connecting one or more switches 320 between the neutral wires 380 of each winding group 405, 410 so that all neutral wires 380 can be in electrical contacts. Such switches 320 may be referred to herein as neutral switches 322 to distinguish them from switches that can place the output wires 330 of winding 310 into electrical contacts. In some of these examples, the armature 300 may be a six-phase armature (i.e., an armature configured to provide six electrical phases) and may be configured to have an electrical phase difference lower than the other electrical phase differences of the armature, as described, for example, with respect to Figure 10B.

[0062] In some examples, the method may further include electrically connecting multiple pairs of output wires 330 (500) such that the electrical phase difference 355 between the electrical phases 340 provided by the pairs of output wires 330 is the same. Herein, “is the same” means that the electrical phase difference is the same as an electrical phase difference 355 that is lower than the electrical phase difference between any other electrical phases. Some or all of the output wires 330 of a pair of output wires 330 configured to provide an electrical phase difference 355 that is lower than any other electrical phase difference, for example, any other electrical phase difference, may be electrically connected (500).

[0063] For example, in Figure 10A, three pairs of output wires can be provided: a first pair including wires 331 and 331', a second pair including wires 332 and 332', and a third pair including wires 333 and 333'. Each of these pairs of output wires 330 can be configured to provide the lowest electrical difference 355. Thus, in some examples, one or more of these pairs of output wires 330 may be electrically connected (500). In one example, wires 331 and 331' (or 332 and 332', or 333 and 333') can be placed in an electrical contact 500. In another example, wire 331 may be electrically connected to wire 331', wire 332 may be electrically connected to wire 332', and wire 333 may be electrically connected to wire 333'.

[0064] Therefore, the method may include providing a number of electrical connections 500 equal to the number of the lowest available electrical phase differences 355 that can be configured to be provided by the armature 300. Allowing circulation after a short circuit current in this way facilitates uniform and rapid heating of the generator insulators, as the current can proceed through all the windings 310. Furthermore, since the short circuit may be partial (as not all output wires 330 are electrically connected to each other as shown in Figure 3A), the required rotor rotation speed and the wind speed acting on the wind turbine blades 120 may be reduced compared to, for example, a complete short circuit where all output wires 330 can be placed in electrical contact as shown in Figure 3A.

[0065] In some examples, the method may include providing one or more electrical connections 500 first and then providing one or more electrical connections 500 later. In this way, the short-circuit current can be used to heat one part of the armature winding first and then another part of the armature winding. In some examples, the part may be heated two or more times. In one example, output wires 331 and 331', as well as output wires 332 and 332', are first placed in the electrical contacts 500 (see Figure 10A), after which the short-circuit current can pass through them. Later, the electrical connection between output wires 331 and 331' can be terminated, and output wires 333 and 333' can be placed in the electrical contacts 500 (see Figure 10A). Thus, the short-circuit current can then pass through wires 332 and 332' and wires 333 and 333'.

[0066] Generally, it is possible to adjust which electrical connections 500 are made, when, and for how long. In any case, a short-circuit current can flow through the wires placed in the electrical contacts 500, heating the generator insulator.

[0067] In some examples, the short-circuit current may circulate through three or more, i.e., through each of all the windings 310. For example, if three electrical connections 500 in switch 320 are provided in Figure 10A, the short-circuit current may flow, for example, through wires 331 and 331', through wires 332 and 332', and through wires 333 and 333', for substantially the same period of time. In some other examples, if the corresponding electrical connections 500 in switch 320 allow current to pass between wires 331 and 331' rather than between wires 332 and 332' and between wires 333 and 333', the short-circuit current may flow through wires 331 and 331'.

[0068] In some examples, the method may further include circulating a short-circuit current through the armature winding 310 for a period of less than 3 hours, preferably less than 2 hours.

[0069] In some examples, the method may further include disabling the passage of current between the shorted output wires 330. In some examples, a switch 320 connected between the output wires 330 of the generator winding 310 can be deactivated, i.e., all electrical connections that the switch 320 can provide can be interrupted. If a switch 322 is connected between the neutral wires 380 of two groups of windings 310, it is not necessary to disable this switch 322 before starting the generator 162.

[0070] In some examples, the method may further include starting the generator 162. For example, after a certain period of time has elapsed since current began to flow through the armature winding 310, which includes one or more switches 320, the generator 162 can be reconnected to the power grid.

[0071] In a further aspect of the present invention, a method 1100 for heating the insulator of a generator 162 of a wind turbine 160 is provided in Figure 11. The wind turbine comprises a rotor 115 including one or more wind turbine blades 120 and a generator 162 including an armature 300.

[0072] The method includes electrically connecting a first output wire 331 of the armature 300 to a second output wire 332 of the armature 300 in block 1110, wherein the armature 300 comprises three or more windings 310, each winding 310 having an output wire 330, and the electrical phase differences 350 between the output wires of the armature are not all the same. That is, the armature 310 is configured to provide an electrical phase difference 355 that is lower than any other electrical phase difference configured to be provided by the armature 310.

[0073] The armature 300 may be, for example, the armature shown in Figure 8 or Figure 10A.

[0074] In some examples, the armature windings 310 may be connected in a star-shaped or Y-shaped circuit configuration.

[0075] In some examples, the armature 300 may be a six-phase armature (i.e., an armature configured to provide six electrical phases) or a nine-phase armature (i.e., an armature configured to provide nine electrical phases). In some of these examples, the six windings 310 may be connected to the same neutral wire 380. In some other examples of these examples, the six windings 310 may be grouped into two groups 405, 410, each group 405, 410 comprising three windings 310 and connected to its own neutral wire 380. In these examples, the method may further include providing an electrical connection 500 by connecting a neutral switch 322 between the neutral wires 380 of each group 405, 410 of the windings 310, for example.

[0076] In some examples, a first output wire 331 and a second output wire 332 may provide a first electrical phase 341 and a second electrical phase 342, respectively, the first electrical phase 341 and the second electrical phase 342 having an electrical phase difference 355 between them that is lower than the electrical phase difference 350 between other, in particular, any other electrical phases 340.

[0077] In some examples, the method may further include providing an electrical connection 500 between all pairs of output wires 330 configured to provide an electrical phase difference 355 that is lower than any other electrical phase difference 350. The description relating to Figure 10A may be applied herein.

[0078] The method includes allowing wind to rotate the rotor 115 in block 1120 in order to induce current in at least electrically connected first output wires 331 and second output wires 332.

[0079] In some examples, a (partial) short-circuit current can be induced in all windings 310 of the armature 300. In some examples, the short-circuit current may circulate in all windings 310 of the armature 300 over the same period of time. In some of these examples, the current can circulate for less than 3 hours.

[0080] The two methods 700 and 1100 described herein may be combined, that is, a method may include features from the other method. For example, method 1100 (Figure 11) may include features described with respect to method 700 (Figure 7). Any of these methods may be used for the armature 300 described later.

[0081] In a further aspect of the present invention, an armature 300 for a generator is provided. The generator may be a generator 162 of a wind turbine 160, and may be a permanent magnet generator in particular. The armature 300 may be any of the armatures 300 described with respect to Figures 8 and 10A.

[0082] As shown in Figure 8, the armature 300 comprises three or more windings 310 configured to provide three or more outputs having different electrical phases 340, where the first winding is configured to provide a first electrical phase 341, the second winding is configured to provide a second electrical phase 342, and the first and second electrical phases are out of phase.

[0083] The armature 300 further comprises a first switch 321 configured to selectively (electrically) connect the output wire 331 of the first winding 311 and the output wire 332 of the second winding 312. The first switch 321, or any switch in general, may provide one or more electrical connections 500.

[0084] Having an armature 300 with at least one switch 320 connected in this manner may make it possible to partially short-circuit the armature windings 310 by rotating the generator rotor and heating the generator insulator without the need for a power converter. This may also reduce the speed at which the wind may need to flow over the wind turbine blades 120.

[0085] In some examples, the armature 300 may be a six-phase armature (i.e., an armature configured to provide six electrical phases) or a nine-phase electrical armature (i.e., an armature configured to provide nine electrical phases).

[0086] As described with respect to the first method (Method 700) above, in some examples the armature 300 may be configured to provide an electrical phase difference 355 that is lower than other electrical phase differences of the armature. In some of these examples the first electrical phase 341 and the second electrical phase 342 may have an electrical phase difference 355 that is lower than the electrical phase difference 350 between other, in particular any other electrical phases 340. The armature 300 can be configured to provide an electrical phase difference 355 that is lower than the electrical phase difference 350 between the first electrical phase 341 and the second electrical phase 342, which is the lowest electrical phase difference 355, i.e., the electrical phase difference 350 between any other electrical phases 340.

[0087] In some of these examples, the armature 300 may include one or more switches 320 configured to provide electrical connections 500 between different pairs of output wires 330, each electrical connection 500 provided between pairs of output wires 330, each electrical connection 500 provided between pairs of output wires 330 configured to provide the same electrical phase difference 350, i.e., an electrical phase difference 355 that is lower than the electrical phase difference 350 between any other electrical phases 340, for example.

[0088] Furthermore, as shown in Figure 8, in some examples the armature windings 310 may be connected in a star configuration. For example, in some of these examples, such as in Figure 8, three or more windings 310 may be connected to the same neutral wire 380.

[0089] In some other examples, three or more windings 310 may be arranged in groups of three windings, for example, and each group 405, 410 may be connected to its own neutral wire 380. In some of these examples, one or more switches 320 (neutral switches 322) may be connected between the neutral wires 380 of the groups to selectively (electrically) connect the neutral wires 380.

[0090] An example of this can be seen in Figure 10A. Figure 10A schematically represents a six-phase armature 300 having six windings 310 arranged in two groups 405, 410 of three-phase windings. Each group 405, 410 is connected to its own neutral wire 380, and a switch 320 (neutral switch 322) connects the two neutral wires 380. In some other examples, the groups of windings 310 may be connected to the same neutral wire 380, and the switches 320, 322 connecting the neutral wire 380 may not be necessary.

[0091] In Figure 10A, switch 320 can enable electrical connections 500 between the outputs 330 of winding 310. In particular, the switch 320 connecting the outputs 330 of winding 310 may be a first switch 321. The first switch 321 may control which output wire 330 is placed on the electrical contact 500 and when.

[0092] Each of the output wires 331, 332, 333, 331', 332', and 333' can provide an electrical phase 340. In some examples, the electrical phase outputs may be such that the electrical phase difference 355 is lower than that of other electrical phase angles. Figure 10B schematically represents an example of such an electrical phase output 360 provided by the armature winding 310 in Figure 10A. In this example, each group of windings 405, 410 provides three-phase electrical phase outputs 490, 490' with substantially equal phase differences. One of these three-phase electrical phase outputs 490, for example, the electrical phase output provided by group 405, is shown by continuous lines 341, 342, and 343, while the other three-phase electrical phase output 490', for example, the electrical phase output provided by group 410, is shown by dashed lines 341', 342', and 343'. The two three-phase electrical phase outputs 490, 490' are separated in this example by an electrical phase difference 450, which is lower than any of the other electrical phase differences. That is, the electrical phase difference 450 is the lowest electrical phase difference in this example, 355.

[0093] Therefore, the switch 320 connecting the output wires in Figure 10A can be configured to provide electrical connections 500 between the output wires that are configured to provide an electrical phase difference 355 lower than any other electrical phase difference. For example, if the output wires 331, 332, 333, 331', 332', and 333' provide electrical phases 341, 342, 343, 341', 342', and 343' respectively, the first switch 321 can enable electrical connections 500 between wires 331 and 331', wires 332 and 332', and wires 333 and 333', as shown in Figure 10A. Thus, a number of electrical connections 500 equal to the number of possible electrical phase differences 355 lower than any of the other electrical phase angles 350 that the armature 300 can be configured to provide can be provided or enabled by the first switch 321.

[0094] In some other examples, instead of having one switch 321 to provide all the electrical connections 500 between the output wires of the winding 310, multiple switches 320 may be provided. For example, one switch may be provided to enable one electrical connection 500. That is, in one example, three switches 320 may be included in Figure 10A to provide each of three connections 500.

[0095] Figure 12 shows an example of a short-circuit current that can circulate through the windings 310 of a six-phase armature 300, such as that in Figure 10A, when the output wires providing the lowest electrical phase, e.g., 331 and 331', 332 and 332', and 333 and 333', are placed at the contacts (lower curve). This curve is compared to the short-circuit current shown in Figure 4 when the entire three-phase armature is short-circuited.

[0096] Figure 13 shows a graph plotting the torque required to reach the current shown in Figure 12 as a function of the rotor rotation speed (lower curve). This curve is compared to the torque shown in Figure 4 when the entire three-phase armature is short-circuited. As can be seen, by using the examples disclosed herein, the required torque can be significantly reduced. Thus, the wind speed around the wind turbine blades 120 that may be required to generate such torque values ​​may be less than that shown in Figure 6, and an armature having one or more switches 320 and the method described throughout this disclosure can provide an efficient generator insulator without the need for a power converter at wind speeds where the entire short circuit of the generator windings 310 cannot induce current.

[0097] In general, any step for assembling the armature 300 according to the present invention, for example as described with respect to Figures 8 to 10B, can be incorporated into any of the methods described herein.

[0098] The armature 300 according to the present invention may be included in the generator 162. Therefore, a generator 162 for, for example, a wind turbine 160 can be provided, comprising the armature 300 disclosed herein. In some examples, the generator 162 may be a permanent magnet generator.

[0099] In some examples, the generator 162 including the armature 300 according to the present invention may be included in the wind turbine 160. Thus, a wind turbine 160 can be provided comprising a wind turbine tower 170, a nacelle 161 at the top of the tower 170, a rotor including one or more wind turbine blades 120 mounted on the nacelle 161, and a generator 162 including the armature 300 described throughout this disclosure, located inside the nacelle 161.

[0100] This specification discloses the present invention, including preferred embodiments, using examples, and enables those skilled in the art to practice the invention, including by constructing and using any device or system and by carrying out any incorporated method. The patentable scope of the present invention is defined by the claims and may include other embodiments that a person skilled in the art may conceive. Such other embodiments are intended to be within the claims if they have structural elements that do not differ from the language of the claims, or if they include equivalent structural elements that do not substantially differ from the language of the claims. A person skilled in the art can construct further embodiments and techniques in accordance with the principles of this application by combining and adapting aspects from the various embodiments described above and other known equivalents for each such aspect. Where reference numerals related to the drawings are placed in parentheses within the claims, those reference numerals are merely for clarity of the claims and should not be construed as limiting the claims. [Explanation of Symbols]

[0101] 1 winding 2 windings 3 windings 4 windings 5 windings 6 windings 20 Yaw System 21 Ring gear 22 Yaw drive device 23 Motor 24 Gearbox 25 pinion 100 pitch bearing 107 Pitch System 108 pinion 109 Ring gear 110 Hub 115 Rotor 120 Wind turbine blades, rotor blades 150 Support surface 160 Wind Turbine 161 Nacer 162 Generators 163 Main rotor shaft 164 Gearbox 165 Support frame, bed plate 166 Generator shaft 170 Wind Turbine Towers 300 Generator armature, six phase armature 310 Armature windings, generator windings, stator windings, armature 311 First winding, first armature winding 312 Second winding, second armature winding 313 Third winding 320 switches 321 First switch 322 Neutral switch 330 output wire, output 331 First output wire 331' Output wire 332 Second output wire 332' Output Wire 333 Output wire 333' Output wire 340 Electrical Phase 341 First electrical phase, continuous line 341' Electrical phase, dashed line 342 Second electrical phase, dashed line, continuous line 342' Electrical phase, dashed line 343 Third electrical phase, electrical phase, continuous line 343' Electrical phase, dashed line 350 Electrical phase difference, electrical phase angle 350' Electrical phase difference 355 Electrical phase difference, electrical difference 360 Electrical Phase Output 370 Total short circuit of winding 380 Neutral Wire 405 Winding Group 410 Winding Group 450 Electrical phase difference 490 Three-phase electrical phase output 490' Three-phase electrical phase output 500 Electrical contacts, electrical connections 700 methods 1100 methods PA pitch axis YA yaw axis

Claims

1. A method (700, 1100) for operating a wind turbine (160) comprising a rotor (115) including one or more wind turbine blades (120) and a generator (162) including an armature (300), The armature (300) comprises three or more windings (310) and is configured to provide three or more electrical phases (340), wherein the first winding (311) is configured to provide a first electrical phase (341), and the second winding (312) is configured to provide a second electrical phase (342), and the second electrical phase (342) and the first electrical phase (341) are out of phase, and the method (700, 1100) is, The armature winding (310) is partially short-circuited (710) by closing the first switch (321) between the output wire (330) of the first winding (311) and the output wire (330) of the second winding (312), The wind acting on the wind turbine blade (120) induces an electric current in the armature winding (330) (720) Method (700, 1100), comprising the armature (300) being configured to provide an electrical phase difference (355) between two of the electrical phases (340) of the armature (300) that is lower than another electrical phase difference (350) between two of the electrical phases (340) of the armature (300).

2. The method according to claim 1 (700, 1100), wherein the first electrical phase (341) and the second electrical phase (342) have an electrical phase difference (350) that is lower than any electrical phase difference between any of the other electrical phases (340).

3. The method (700, 1100) of claim 1 or 2, wherein the armature (300) comprises two or more winding groups (405, 410), each group (405, 410) includes its own neutral wire (380), and the method (700, 1100) further comprises connecting one or more switches (320) between the neutral wires (380) of each group of windings (405, 410) so that all of the neutral wires (380) can be at an electrical contact (500).

4. The method according to claim 3 (700, 1100), further comprising electrically connecting a plurality of pairs of output wires (330), wherein the electrical phase difference (355) between the electrical phases (340) provided by the pairs of output wires (330) is the same.

5. The method according to any one of claims 1 to 4 (700, 1100), further comprising circulating a short-circuit current through each of the three or more windings (310).

6. The method according to any one of claims 1 to 5 (700, 1100), further comprising circulating a short-circuit current through the armature winding (330) for a period of less than three hours.

7. The method according to any one of claims 1 to 6 (700, 1100), further comprising disabling the passage of current between the short-circuited output wires (330).

8. The method according to claim 7 (700, 1100), further comprising starting the operation of the generator (162).

9. an armature (300) for a wind turbine generator (162), Three or more windings (311, 312, 313) configured to provide three or more electrical phases (340), wherein the first winding (311) is configured to provide a first electrical phase (341), the second winding (312) is configured to provide a second electrical phase (342), and the first electrical phase (341) and the second electrical phase (342) are out of phase. A first switch (321) configured to selectively connect the output wire (330) of the first winding (311) and the output wire (330) of the second winding (312), and An armature (300) comprising the first electrical phase (341) and the second electrical phase (342) having an electrical phase difference (450) lower than the electrical phase difference (350, 350') between the other electrical phases (340).

10. The armature (300) according to claim 9, comprising one or more switches (320) configured to provide electrical connections (500) between different pairs of output wires (330), each electrical connection (500) provided between pairs of output wires (330) configured to provide electrical phases (340) having the same electrical phase difference (350).

11. The armature (300) according to claim 9 or claim 10, wherein the armature (300) is a six-phase armature or a nine-phase armature.

12. A generator (162) for a wind turbine (160), comprising an armature (300) according to any one of claims 9 to 11.

13. A wind turbine (160) comprising a wind turbine tower (170), a nacelle (161) at the top of the tower (170), a rotor (115) including one or more wind turbine blades (120) mounted on the nacelle (161), and a generator (162) according to claim 12.

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