Operation of a generator with a faulty coil

Abstract

The present invention relates to a method for operating a generator when at least one coil is faulty. [Solution] A method for operating a generator (2) having a stator (3) having at least one multiphase winding set (4_1), wherein the winding set comprises, for each phase, a plurality of coils (5_1, 5_1*, 5_1, 16_1) arranged in the intertooth slots of the stator and connected in particular in series and / or in parallel, wherein, in the event of failure of at least one coil (5_1*), the method includes electrically disconnecting all or part of the failed coil (5_1*) and optionally a normal coil from a first conductor (7a) and other first conductors (7b), and operating the generator (2) without using the disconnected failed coil (5_1*), in particular holding the disconnected failed coil in a predetermined position on the stator during the operation of the generator.

Description

Technical Field

[0001] The present invention relates to a method for operating a generator when at least one coil is faulty. The present invention further relates to a generator system and a wind turbine.

[0002] Background Art European Patent Application Publication No. 2629402 discloses a method for repairing a winding in a generator, which cuts the winding on one side of a tooth to divide the winding into two parts and removes the two winding parts from the tooth. Further, an alternative partial coil is slid on the tooth and the incomplete turns are connected to a plurality of conductor parts.

[0003] One or more faulty coils in a generator (turbine) are usually short-circuited turns and / or coils. Conventionally, until a segment containing one or more faulty coils is replaced (in the case of a segmented generator stator) or until the entire stator can be replaced (in the case of a non-segmented generator stator), it will cause a complete turbine shutdown. Continuing operation with a short-circuited coil generates a high local temperature, causing greater damage to the remaining part of the turbine and thus a risk of igniting the entire turbine. Usually, it is impossible to repair a faulty coil. Replacement may require generator disassembly equipment (e.g., a full-size crane) that can take weeks to months in some situations, such as the remoteness of onshore areas, weather conditions in offshore areas, etc., so it may not be possible in the short term. This can lead to a significant loss of AEP (annual total power generation), especially during the windy season when replacement of individual segments or the entire segment of the stator is more difficult and likely to be delayed due to environmental reasons.

[0004] If one or more stator coils fail, the turbine must typically remain stationary until the segment containing the faulty coil is replaced. Offshore direct-drive turbines have two separate electrical systems, but it is dangerous to continue operation by the healthy system at 50% generator capacity while the transducer of the faulty system is disconnected. This is because the magnetic coupling of these two systems creates a circulating current that flows through a low-resistance path in the faulty coil. This circulating current can cause further damage to the rest of the generator / turbine, eventually triggering a fire alarm, or even causing an actual fire if the fire alarm does not function properly.

[0005] Therefore, there may be a demand for a method of operating a generator with a faulty coil, a generator, and a wind turbine including the generator, which can improve the efficiency of the generator and, in particular, improve the power output and / or operating time of the generator compared to conventional methods.

[0006] Summary of the Invention In embodiments of the present invention, the isolation of one or more faulty coils is proposed, which can be performed by one or two technicians in a few hours. In this case, the generator system can be restored to operation at a high load capacity, i.e., a capacity close to the maximum power depending on the stator winding design and the number of faulty coils.

[0007] One embodiment of the present invention provides a method for operating a generator having a stator having at least one set of multiphase windings (connected, for example, to at least one transducer), wherein the set of windings comprises, for each phase, a plurality of coils arranged in intertooth slots of the stator and connected in particular in series and / or in parallel, and in the event of failure of at least one coil, the method includes electrically disconnecting the faulty coil or a portion of the faulty coil from a first conductor and other first conductors, and holding the disconnected faulty coil in place on the stator while operating the generator.

[0008] The method can be implemented, for example, in software and / or hardware, and / or performed by one or more technicians or maintenance workers, and / or by a control unit that includes arithmetic / logic circuits and is adapted to control a generator.

[0009] The stator may be a single-segment or multi-segment stator. The stator may include multiple polyphase winding sets, but in some embodiments, it may include only one polyphase winding set. In particular, (at least one) polyphase winding set can provide three or more electrical phases. The winding set can be wound or positioned within the inter-tooth slots according to a concentrated winding topology or a distributed winding topology.

[0010] A generator (for example, in a wind turbine) may further have a rotor, such as an outer rotor, to which permanent magnets are attached. The rotor is rotatable about an axis parallel to the axial direction. The generator may have a first axial end and a second axial end. In particular, a faulty coil can be isolated by applying one or more cuts or interruptions to the first axial end, which provides access to the windings. Embodiments may also apply to generators or motors other than wind turbine generators.

[0011] A winding set can include one or more coil rows (also called branches) connected in parallel to each other for each phase, and each coil row contains one or more coils connected in series. Other configurations are also possible.

[0012] Electrical disconnection may involve mechanically cutting and / or sawing conductive (winding or wire metal) material to interrupt all current flowing into or out of a faulty coil. The first conductor and other first conductors may have previously carried current towards the coil that is now faulty and may derive current from the coil that was previously normal but is now faulty.

[0013] A faulty coil may include, for example, damage to the insulation and / or a short circuit within itself, or damage between one or more other coils or windings belonging to one or more other phases, or a short circuit to the stator or neutral phase. The fault may, in particular, generate physical heat if left uncorrected. The entire faulty coil, only a portion of the faulty coil, or a part of the faulty coil may be electrically disconnected, depending on the application and design and geometry and / or location of the coil being considered. In particular, the conductor portion that previously electrically connected the faulty coil to the first conductor may be cut or interrupted, and other conductor portions between the faulty coil and other first conductors may also be cut or interrupted. The first axial end may correspond, for example, to a non-driven end, i.e., an axial end where no hub with multiple rotor blades is located.

[0014] A faulty coil may include, for example, a faulty insulator to any conductive material that should not conduct current to or from the faulty coil during normal operation.

[0015] In embodiments of the present invention, it becomes unnecessary to remove all or part of a faulty coil from the generator. By electrically disconnecting the faulty coil, it can be made so that it is no longer part of the electrical system. This allows the generator to continue operating without the need for the troublesome or time-consuming removal of the faulty coil. This allows the generator to be restarted quickly.

[0016] According to one embodiment of the present invention, disconnecting a faulty coil or a portion of a faulty coil includes disconnecting a first electrical connection between the faulty coil or a portion of a faulty coil and a first conductor or a portion of a first conductor, and disconnecting another first electrical connection between the faulty coil or a portion of a faulty coil and another first conductor or another portion of a first conductor, wherein disconnecting the first electrical connection and / or the other first electrical connection includes cutting through the entire conductive material, i.e., sawing.

[0017] The first electrical connection / second electrical connection can be cut or severed, for example, using a knife and / or saw that can be operated by a maintenance worker. In particular, the first conductor and the other first conductor can be prevented from being interfered with or damaged when the electrical connection is interrupted. Advantageous in this case, the first conductor and the other first conductor can still be further connected to other coils of a functioning generator to receive or supply current, thereby allowing the generator to continue operating.

[0018] According to one embodiment of the present invention, before the faulty coil is disconnected, the faulty coil is connected to a first transducer via a first conductor configured in particular as a busbar.

[0019] The first transducer (and similarly, the second transducer as an optional means connected to the second winding set) may include a plurality of controllable switches, for example, a power transistor connected between two DC terminals. The first and second transducers can convert a variable frequency power flow to a substantially fixed frequency power flow having, for example, 50 Hz or 60 Hz. The first (and second) transducers may ultimately enable control of the generator by one or more current criteria, power criteria, or torque criteria selected, for example, depending on the applied control mode.

[0020] According to one embodiment of the present invention, by disconnecting the faulty coil, at least one or all of the non-faulty coils remain connected in parallel to the faulty coil, which was previously connected to the first conductor and other first conductors.

[0021] In particular, all non-faulty (e.g., normal) coils that are not connected in series with the faulty coil can be kept connected to the first conductor and other first conductors. This allows the generator to continue operating with at least a substantial fraction of the non-faulty coils. The non-faulty coils do not cause, or contain, any short circuits to any conductors that should be electrically isolated from the (i.e., disconnected) coil under consideration in accordance with normal operation.

[0022] According to one embodiment of the present invention, the method further includes, in order to reduce rattle and / or vibration, disconnecting a non-faulty coil (or a coil that may fail) from the first conductor and other first conductors, and holding it in a predetermined position in the stator, in particular, substantially opposite the faulty coil and spatially offset in the stator by substantially 180° from the faulty coil.

[0023] Furthermore, by disconnecting the coils (whether normal or not) opposite the faulty coil, the resulting torque imbalance or any other mechanical or electrical imbalance can be reduced or even avoided. In particular, the entire coil row positioned opposite the faulty coil (row) can be disconnected from the first conductor and the other first conductors. According to other embodiments, in particular, if rattle and / or vibration are not observed to exceed, for example, a threshold, all other non-faulty opposing coils can be kept connected to the first conductor and the other first conductors.

[0024] According to one embodiment of the present invention, the method further comprises electrically and / or mechanically isolating and / or disconnecting a faulty coil or a portion of a faulty coil at a portion of a second axial end, wherein the disconnection of the first electrical connection and other first electrical connections is performed at the first axial end (this prevents, for example, circulating current in the faulty coil).

[0025] This also allows for a third interruption or disconnection at the faulty coil to avoid any circulating current in the faulty coil, for example. The second axial end may correspond to an axial end (e.g., a drive end) where a hub with multiple rotor blades is located.

[0026] According to one embodiment of the present invention, the coils of one winding set are initially connected in a star configuration or a delta configuration, and a first conductor and other first conductors are formed by a first busbar and other first busbars or include a first busbar and other first busbars, and when the coils of one winding set are initially connected in a star configuration, the first conductor carries the power of one non-neutral phase (e.g., A, B, C) and the other first conductor carries the power of the neutral phase (e.g., N).

[0027] This provides great flexibility. The first busbar can be connected to one terminal of the first converter. Further first busbars and still other first busbars can be provided for other electrical phases, for example, can be connected to other terminals of the first converter. All of the first busbar, the further first busbars, the still other first busbars and the other first busbars can be provided substantially at the first axial end of the generator, whereby easy access can be achieved by conductors supplying current for power production. The neutral phase can be present at the star point when the coils of the winding set are electrically connected in a star configuration. The star point (i.e., representing the neutral phase) need not be connected to any converter.

[0028] According to an embodiment of the present invention, a failed coil is a member of a coil string consisting of coils connected in series, a first end of the coil string has been connected to a first conductor until then, a second end of the coil string has been connected to another first conductor until then, interrupting the first electrical connection includes interrupting the connection between the first end of the coil string and the first conductor, and interrupting the other first electrical connection includes interrupting the connection between the second end of the coil string and the other first conductor.

[0029] In the context of the present application, the coil string can also be referred to as a "branch". The coil string can include, for example, two or three or more coils that are spatially adjacent to each other in the circumferential direction (connected in series). For example, the first coil of the coil string can include a plurality of turns centered on the first tooth or a plurality of first teeth, in which case the turns are connected to a second coil including a plurality of turns centered on a second tooth or a plurality of second teeth that are (directly) in contact with the first tooth or the plurality of first teeth in the circumferential direction. The coil string can include, for example, two, three, four, five or more coils. This can support the design of conventional windings.

[0030] According to one embodiment, the coil train under consideration includes at least one failed coil, and the entire coil train can be electrically disconnected from a first conductor and another first conductor. This can be made possible because the electrical connection between the coil trains including the first conductor and another first conductor becomes accessible to the operator.

[0031] According to one embodiment of the present invention, in particular, a stator having a plurality of stator segments has a first polyphase winding set that was previously connected to a first converter, and here, when a failed coil is associated with a first phase in the first winding set, operating the generator further includes, with respect to the first winding set, whether a first current reference associated with the first phase is reduced or not reduced, and whether a first current reference associated with a phase different from the first phase is reduced or not reduced, with respect to the operation when the coil was not failed, where in particular, the first current reference is supplied to the first converter to control the first converter.

[0032] The failed coil can be considered to be associated with a first phase provided in the first winding set in the sense that when the currently failed coil was normal, the coil that was normal until then and then failed carried the power corresponding to the first phase in the first winding set. The first current reference can represent, for example, the d component and / or the q component of the reference current in the synchronous rotating dq coordinate system.

[0033] Based on a first current reference, the first winding set is controllable, in particular, via a first transducer. Instead of defining or setting a current reference, a power reference and / or a torque reference and / or a voltage reference can also be set, and can be reduced or not reduced according to the requirements of a particular application. This makes it possible to provide various modes of reducing or not reducing the current reference with respect to the electrical phase associated with the faulty coil or the current reference with respect to any electrical phase relative to the faulty coil. Whether or not to reduce can be made dependent on other operating parameters, such as noise, vibration / rattling, and can also be set depending on these other operating parameters.

[0034] The embodiments described above or those listed above (but not limited to them) also apply to generators having a single set of polyphase windings, but these embodiments and / or other embodiments also apply to generators having multiple sets of polyphase windings, for example, two, three, four, five or more sets of (independent) windings. Each set of polyphase windings may be connected to a corresponding converter.

[0035] According to one embodiment of the present invention, the stator further has at least one second polyphase winding set which was previously connected in particular to a second transducer, wherein if a faulty coil is associated with a first phase in the first winding set, operating the generator further includes at least one of reducing or not reducing a second current reference associated with the first phase with respect to the second winding set with respect to the operation as if the coil had not failed; reducing or not reducing a second current reference associated with a phase other than the first phase with respect to the operation as if the coil had not failed, in particular the second current reference is supplied to the second transducer to control the second transducer.

[0036] Some embodiments of the present invention relate to an electric generator of a multi-winding set and a method for operating an electric generator of a multi-winding set. Furthermore, any reduction or non-reduction of a second current reference, relating to or associated with an electrical phase (associated with a faulty coil), or not relating to or associated with an electrical phase (associated with a faulty coil), can be performed in response to monitoring of other electrical or operating parameters, such as vibration / rattling and / or any imbalance in a mechanical or electrical sense. This can improve the performance of the generator operation.

[0037] According to one embodiment of the present invention, the first current reference is set such that the first current reference and the second current reference are reduced by substantially the same percentage, or the first current reference is reduced and the second current reference is not reduced, and / or the current carried in any of the parallel-connected coils or any of the parallel-connected coil rows of the first winding set for the phase under consideration is not substantially higher than in a non-faulted state.

[0038] If the first current reference / second current reference or power reference or torque reference is set to the same percentage or substantially reduced by the same percentage, the balance of the generator operation can be improved. In other embodiments, power output can be kept as high as possible while potentially tolerating any vibration or rattle problems. Furthermore, coil overload can be avoided, thereby improving or extending the lifespan of the generator or, in particular, the stator windings.

[0039] According to one embodiment of the present invention, the stator comprises a plurality of n1 first stator segments on which a first winding set is located, wherein in each of the first stator segments a plurality of m1 coil rows or coil branches are connected in parallel (between a first conductor and other first conductors), and a first current reference is set or reduced depending on the number and / or location of n1 and / or m1 and / or faulty coils, and / or the stator comprises a plurality of n2 second stator segments on which a second winding set is located, wherein in each of the second stator segments a plurality of m2 coil rows or coil branches are connected in parallel (between a second conductor and other second conductors), and a second current reference is set or reduced depending on the number and / or location of n2 and / or m2 and / or faulty coils.

[0040] The methodology for deriving the maximum current is described below. The current reference can be set to this maximum current. However, the present invention is not limited to such a specific methodology.

[0041] After a faulty coil is disconnected, the current supplied to the system can be reduced accordingly according to the following formulas to maintain the current in each coil at its rated current so that it does not exceed the current before the fault occurred: 1. If the disconnection is applied to only one phase (or the coil belonging to it), the maximum current is:

number

number

number

[0042] The current reference described above can be set to the maximum current calculated in this way. Further reduction or non-reduction of the current can depend on other operating parameters, such as noise and vibration / rattling, and can be set depending on such other operating parameters.

[0043] Please understand that any features described, explained, presented, or applied to methods of operating the generator individually or in any combination are applicable to or can be provided to a generator system according to one embodiment of the present invention, individually or in any combination, and vice versa.

[0044] According to one embodiment of the present invention, a generator system is provided, comprising a generator having a stator having at least one set of polyphase windings (connected, for example, to at least one transducer), wherein the set of windings comprises, for each phase, a plurality of coils arranged in inter-tooth slots of the stator and connected in particular in series and / or in parallel, wherein at least one of the plurality of coils is faulty and electrically disconnected from a first conductor and other first conductors; and a control device adapted to operate the generator without using the faulty coil, thereby holding the faulty coil, which is in particular disconnected, in a predetermined position on the stator.

[0045] The generator system can be configured to perform the method of operating the generator described or presented in one of the embodiments described above.

[0046] According to one embodiment of the present invention, a wind turbine is provided, comprising a hub to which a plurality of rotor blades are attached on top, a generator system according to the above-described embodiment, and a generator rotor coupled to the hub.

[0047] The above-described and further embodiments of the present invention will become apparent from the examples described below, and will be explained with reference to these examples. The present invention will be described in detail below in relation to the examples, but the present invention is not limited thereto.

[0048] Embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiments shown or described. [Brief explanation of the drawing]

[0049] [Figure 1] This is a schematic diagram showing a wind turbine according to one embodiment of the present invention, including a generator system according to one embodiment of the present invention. [Figure 2]This figure shows an embodiment in which a faulty coil is disconnected and / or interrupted in two or more parts. [Figure 3] This figure shows an embodiment in which a faulty coil is disconnected and / or interrupted in two or more parts. [Figure 4] This figure shows an embodiment in which a faulty coil is disconnected and / or interrupted in two or more parts. [Figure 5] This diagram schematically shows two multiphase winding set stators with one coil failure scenario. [Figure 6] This diagram schematically shows two multiphase winding set stators with different coil failure scenarios. [Figure 7] This diagram schematically shows two multiphase winding set stators with different coil failure scenarios. [Figure 8] This diagram schematically shows two multiphase winding set stators with different coil failure scenarios.

[0050] Detailed explanation The wind turbine 10 schematically shown in Figure 1 has a hub 11 to which a plurality of rotor blades 12 are attached. The hub 11 is configured to rotate about a rotation axis 13 that is oriented vertically in Figure 1. The wind turbine 10 further includes a generator system 1 according to one embodiment of the present invention, in which a generator rotor 6 is coupled to the hub 11. The generator rotor 6 includes a plurality of permanent magnets 14.

[0051] The rotor's rotation axis 13 is parallel to the axial direction. Figure 1 shows the winding system and stator in an exploded view. In this exploded view, the circumferential direction is parallel to the horizontal direction, and the rotor extends in the horizontal direction 30 of Figure 1.

[0052] The generator system 1 includes a generator 2, which has a stator 3 with at least one polyphase winding set 4_1, the polyphase winding set 4_1 including a plurality of coils 5_1 for each phase, arranged in intertooth slots (not shown) of the stator 3. In the embodiment shown in Figure 1, the plurality of coils 5_1 are connected in series. At least one of the coils, i.e., coil 5_1*, is faulty.

[0053] In the generator system 1 shown in Figure 1, the faulty coil 5_1* is electrically isolated from the first conductor 7a and the other first conductor 7b. The generator system 1 further includes a control device 8 adapted to operate the generator 2 without using the faulty coil 5_1*, thereby holding the particularly isolated faulty coil 5_1* in place within the stator 3.

[0054] During the operation of generator 2, the faulty coil 5_1* is electrically isolated from the first conductor 7a and the other first conductor 7b. Furthermore, generator 2 operates without using the faulty coil 5_1*.

[0055] To disconnect the faulty coil 5_1*, the present method includes disconnecting the first electrical connection 9a between the faulty coil 5_1* and the first conductor 7a, and further disconnecting the other first electrical connection 9b between the faulty coil 5_1* and the other first conductor 7b. Prior to disconnection, the faulty coil 5_1* was connected to the first transducer 15_1 via the first conductor 7a.

[0056] The multiphase winding set 4_1 still contains the other coil 16_1, which remains connected to the first conductor 7a and the other first conductor 7b.

[0057] In the embodiment shown in Figure 1, the faulty coil 5_1* is similarly isolated and / or cut at the portion of the second axial end 17. This disconnects the electrical connection 18 at the second axial end 17 of the faulty coil 5_1*. In the illustrated embodiment, it should be understood that the disconnection of the first electrical connection 9a and the other first electrical connection 9b is performed at the first axial end 19.

[0058] In the embodiments shown in Figure 1 and subsequent figures, the coils of the winding set 4_1 are initially connected in a star configuration, with a first conductor 7a carrying power for one non-neutral phase (phase U or phase A in this embodiment) and a second conductor 7c carrying power for the neutral phase (e.g., N).

[0059] In the embodiment shown in Figure 1, the faulty coil 5_1* is a component of coil array 20a_1, which consists of coils 5_1, 5_1*, 5_1 connected in series. The first coil end 21a of coil array 20a_1 was previously connected to the first conductor 7a, and the second coil end 21b of coil array 20a_1 was previously connected to the other first conductor 7b. A configuration is provided to disconnect the connection between the first coil end 21a and the first conductor 7a in order to disconnect the first electrical connection 9a. A configuration is provided to disconnect the connection between the second coil end 21b of coil array and the other first conductor 7b in order to disconnect the second electrical connection 9b.

[0060] As can be seen from Figure 1, until then, coil array 20a_1 (which has the faulty coil 5_1*) and coil arrays 22c_1 and 22b_1 were connected in parallel to the first conductor 7a and the other first conductor 7b, respectively.

[0061] Figures 2 to 4 show how to isolate / cut a faulty coil from the conductor in an actual embodiment.

[0062] Figures 5 to 8 schematically show two winding set generators, each having a first polyphase winding set 4_1 (located in stator segments 1 to n) and a second polyphase winding set 4_2 (located in stator segments n+1 to 2n), which are connected to a first transducer 15_1 and a second transducer 15_2, respectively. The control device 8 controls the two transducers 15_1 and 15_2 by supplying their respective control signals 31_1 and 31_2. The control signals may, for example, represent a first current reference and a second current reference, respectively.

[0063] The generator system 1 shown in Figure 5 includes, for example, m parallel branches or coil rows 20a_1, 20b_1, 20c_1 for phase A1 of the first segment 23_1_1 with respect to a first winding set 4_1. As shown, other coil rows of the first segment 23_1_1 are provided for other phases B1, C1 and are connected to conductors 7c, 7d. Thus, coil rows 20a_1, 20b_1, 20c_1 can have multiple coils connected in series, similar to coil row 20a_1 shown in Figure 1. In the embodiment shown in Figure 5, coil row 20a_1 includes at least one faulty coil, in which case it is disconnected from the first conductor 7a and the other first conductor 7b (neutral point).

[0064] Figure 5 shows an example of a generator design having 2n segments (23_1_1, ..., 23_1_n) and (23_2_1, ..., 23_2_n) distributed to have two winding systems 4_1 and 4_2. In each segment, each phase is designed to have m parallel branches. Phase A1 of segment 1 has one branch (20a_1) that has been disconnected due to a faulty coil. The proposed solution explains that in this example, the current level of phase A in winding system 4_2 should be reduced accordingly. Thus, the current level in phase A is also reduced as seen by either converter. The reduced current level must ensure that the current in each branch does not exceed the normal level at which the rated current is supplied, and at the same time, the line voltage is also below the rated voltage.

[0065] Taking m=2, n=6 as an example, the current in system 4_1 must be reduced by 50% considering the current and voltage limits mentioned above. The current in system 4_2 must also be reduced by 50%. Thus, 50% of the rated output power can be achieved without problems such as overheating, high noise and vibration, and rattle of the magnet modules. If rattle of the magnet modules is not a significant problem (for example, if the magnet modules have bolted or adhesive mounting points), the current in system 4_2 can be kept constant (i.e., fully loaded). This allows 75% of the rated output power to be achieved.

[0066] The solutions described are applicable to, but not limited to, different failure conditions and different disconnection scenarios shown as examples in Figures 6 to 8. Figures 6 to 8 should be understood not only as showing failure conditions, but also as showing different disconnection options for normal coils. In particular, in Figure 8, only phase A has a faulty coil, but phases B and C may also be disconnected, for example, to balance the three-phase system.

[0067] In the scenario shown in Figure 6, each of the coil arrays 20a_1, 20b_1, and 20c_1 contains at least one coil that is disconnected from the system, i.e., disconnected from the first conductor 7a and the other first conductor 7b.

[0068] In the case of the failure shown in Figure 6, all coils of phase A in one segment of system 4_1 are disconnected. Taking m=2, n=6 as an example, the currents in both system 4_1 and system 4_2 must be reduced to 25%, taking into account the current and voltage limits mentioned above. This allows 25% of the rated output power to be achieved without problems such as overheating and magnet module rattle. If magnet module rattle is not a significant problem (for example, if the magnet modules have bolted or adhesive mounting), the current in system 4_2 can be kept constant (i.e., fully loaded). This allows 62.5% of the rated output power to be achieved.

[0069] In the scenario shown in Figure 7, the coil row 20a_1 of the first winding set 4_1 and the coil row 20a_2 of the second winding set 4_2 each contain at least one coil separated from the first conductors 7a, 7a' and the other first conductors 7b, 7b', respectively.

[0070] In the fault shown in Figure 7, taking m=2 and n=6 as an example, if one coil of phase A in one segment of system 4_1 is disconnected, and then another coil of phase A in one segment of system 4_2 is disconnected, the currents in both system 4_1 and system 4_2 must be reduced by 50%, taking into account the current and voltage limits mentioned above. This allows 50% of the rated output power to be achieved without problems such as overheating and magnet module rattle. Even if magnet module rattle is not a significant problem (for example, if the magnet module has bolted or adhesive mounting), the current in system 4_2 must still be reduced due to the current and voltage limits. This also allows 50% of the rated output power to be achieved.

[0071] In the embodiment shown in Figure 8, the first winding set 4_1 includes, according to one embodiment, at least one coil separated from the first conductor 7a and the second conductor 7b, in the coil array 20a_1 for phase A1, the coil array 24a_1 for phase B1, and the coil array 25a_1 for phase C1.

[0072] In the fault shown in Figure 8, taking m=2 and n=6 as an example, if one coil in each of phases A, B, and C of one segment of system 4_1 is disconnected, the currents in both system 4_1 and system 4_2 must be reduced by 50% in relation to the rattle problem of the magnet module. This allows 50% of the rated output power to be achieved. If the rattle of the magnet module is not a significant problem (for example, if the magnet module has bolted or adhesive mounting), the current in system 4_2 can be kept constant (i.e., fully loaded). Also, the reduction in the current in system 4_1 can be reduced by only 16.7% instead of 50%. Thus, 91.7% of the rated output power can be achieved.

[0073] The faulty coil can be easily disconnected from the generator busbar on the non-driven end, and thus it is no longer part of the generator's electrical system. Furthermore, to prevent circulating current, it can be disconnected and released through the end winding on the driven end, allowing the turbine to continue operating safely. The faulty coil is detachable, and the turbine is restored to operation, for example, at 70% load capacity.

[0074] Limiting the achievement of higher power was vibration caused by electrical imbalances in the system and / or rattles in the magnet modules and / or unbalanced forces generated by unbalanced magnetic circuits. A way to improve this may be symmetric coil isolation, i.e., removing a faulty coil from its opposing healthy coil. Depending on the situation, the number of faulty coils, and their locations, this scenario may be considered an option for improving the maximum possible power capacity, but at the same time, it may be necessary to replace the non-faulty segments.

[0075] The advantage of this operation is that it removes the faulty coil (stator failure) and safely restores the stopped turbine to operation with relatively high power capacity at very low cost and in a short time. This means a significant increase in AEP when segment replacement (disassembly of the generator) is virtually impossible.

[0076] Another significant advantage is that, as such failures become more likely due to the aging degradation of the insulation system, and segment replacement is not cost-effective, coil isolation allows the turbine to continue operating, thus avoiding segment replacement, which is particularly beneficial as the turbine approaches the end of its lifespan. In other words, the turbine's lifespan is potentially extended.

[0077] Embodiments of the present invention can enable the continued operation of a turbine having a generator with one or more faulty coils in order to maintain energy production. This is done by physically disconnecting the faulty coil and, if applicable, other normal coils (coil head disconnection), thereby ensuring safe and reliable turbine operation, i.e., turbine operation with low noise and low vibration, and without unbalanced magnetic attraction and rattle of the magnet module. At the same time, this may also include a reduction in the level of current passing through the corresponding normal coil. In a multiphase winding generator system, the reduction may be similar for each system, i.e., including the system that does not contain the disconnected coil.

[0078] The advantage of each embodiment is that it enables power production equivalent to or greater than that of the reduced converter operation cost (RCO) solution. In offshore locations, replacement may be impossible for several weeks to months due to weather, but it is possible to maintain the operation of a turbine with a generator that has a faulty coil, i.e., to maintain power production until the generator can be replaced.

[0079] The above solution may also include reducing the current in all three phases of the normal coil in a normal winding system, which is the counterpart to the faulty coil in the abnormal winding system. This may also require reducing the current levels of the normal coils in the other two phases of the faulty coil in the faulty winding system.

[0080] Note that the word "comprising" does not exclude other elements or steps, and the words "a, an" or "a, an" do not exclude multiple elements. Furthermore, elements described in relation to multiple different embodiments can be combined. Additionally, note that reference numerals in the claims should not be construed as limiting the scope of each claim.

Claims

1. A method for operating a generator (2) having a stator (3) having at least one polyphase winding set (4_1), The winding set comprises, for each phase, a plurality of coils (5_1, 5_1*, 5_1) arranged in the intertooth slots of the stator and connected in particular in series and / or in parallel, and in the event that at least one coil (5_1*) fails, The method described above is Electrically disconnecting the faulty coil (5_1*) or a part of the faulty coil from the first conductor (7a) and the other first conductor (7b), By operating the generator (2) without using the faulty coil (5_1*), in particular, the disconnected faulty coil is held in a predetermined position on the stator during the operation of the generator. Methods that include...

2. Disconnecting the faulty coil (5_1*) or a part of the faulty coil is To disconnect the first electrical connection (9a) between the faulty coil (5_1*) or a part of the faulty coil and the first conductor (7a) or a part of the first conductor, To interrupt the other first electrical connection (9b) between the faulty coil (5_1*) or a part of the faulty coil and the other first conductor or a part of the other first conductor (7b) Includes, Disconnecting each of the first electrical connections and / or the other first electrical connections includes, in particular, cutting through the entire conductive material, i.e., sawing it. The method according to claim 1.

3. Before disconnecting the faulty coil (5_1*), the faulty coil is connected to the first transducer (15_1) via the first conductor (7a), which is configured in particular as a busbar. The method according to claim 1 or 2.

4. By disconnecting the faulty coil (5_1*), at least one or all of the non-faulty coils (16_1) remain connected in parallel to the faulty coil, which was previously connected to the first conductor and the other first conductor. The method according to any one of claims 1 to 3.

5. The above method further, In particular to reduce rattle and / or vibration and / or magnetic load imbalance, a non-faulty coil, which is spatially positioned in the stator substantially opposite the faulty coil and substantially 180° offset from the faulty coil, is isolated from the first conductor and the other first conductor, and is particularly held in a predetermined position in the stator. including, The method according to any one of claims 1 to 4.

6. The above method further, The method involves electrically and / or mechanically isolating and / or disconnecting the faulty coil (5_1*) or a portion of the faulty coil at the second axial end (17), in particular by disconnecting the first electrical connection and other first electrical connections at the first axial end (19). including, The method according to any one of claims 1 to 5.

7. The following, namely, The coils of one winding set are initially connected in a star configuration or a delta configuration; The first conductor (7a) and the other first conductor (7b) are formed by or include a first busbar and another first busbar; When the coils of one winding set are initially connected in a star configuration, the first conductor carries the power of one non-neutral phase (A, B, C), and the other first conductor carries the power of the neutral phase (N); At least one of the following applies: The method according to any one of claims 1 to 6.

8. The faulty coil (5_1*) is a component of a coil array (20a_1) of coils connected in series, the first coil end (21a) of the coil array was previously connected to the first conductor (7a), and the second coil end (21b) of the coil array was previously connected to the other first conductor (7b). Disconnecting the first electrical connection includes disconnecting the connection between the first coil end (21a) of the coil array and the first conductor, Disconnecting the other first electrical connection includes disconnecting the connection between the second coil end (21b) of the coil array and the other first conductor. The method according to any one of claims 1 to 7.

9. In particular, the stator having multiple stator segments (23_1_1, ..., 23_1_n) has a first multiphase winding set (4_1) that was previously connected to a first converter (15_1), and here, If the faulty coil (5_1*) is associated with the first phase (A1) in the first winding set (4_1), then operating the generator further... With respect to the operation when the coil is not faulty, the first current reference (31_1) associated with the first phase (A1) is reduced or not reduced with respect to the first winding set (4_1); With respect to the operation when the coil is not faulty, reduce or not reduce the first current reference associated with a phase different from the first phase for the first winding set; Includes at least one of the following: In particular, the first current reference is supplied to the first converter to control the first converter. The method according to any one of claims 1 to 8.

10. The stator further has at least one second polyphase winding set (4_2), which was previously connected to a second transducer (15_2), where, If the faulty coil (5_1*) is associated with the first phase (A1) in the first winding set (4_1), then operating the generator is further... With respect to the operation when the coil is not faulty, the second current reference (31_2) associated with the first phase (A2) is reduced or not reduced with respect to the second winding set (4_2); With respect to the operation when the coil is not faulty, reduce or not reduce the second current reference associated with a phase different from the first phase for the second winding set; Includes at least one of the following: In particular, the second current reference is supplied to the second transducer to control the second transducer. The method according to claim 9.

11. The first current reference (31_1) and the second current reference (31_2) are reduced by substantially the same percentage, or The first current standard is reduced, the second current standard is not reduced, and / or A first current reference is established for at least one phase, particularly the faulty phase, or all of the phases among the multiple phases, such that the current carried in any of the parallel-connected coils or any of the parallel-connected coil rows of the first winding set for the phase under consideration is not substantially higher than in a non-faulted state. The method according to claim 10.

12. The stator comprises a plurality of n1 first stator segments (23_1_1, ..., 23_1_n1) on which the first winding set (4_2) is located, and in each of the first stator segments, a plurality of m1 coil rows or coil branches are connected in parallel (between the first conductor and the other first conductor), and the first current reference is set or reduced depending on the number and / or location of n1 and / or m1 and / or faulty coils, and / or The stator comprises a plurality of n2 second stator segments (23_2_1, ..., 23_2_n2) on which the second winding set is located, wherein in each of the second stator segments, a plurality of m2 coil rows or coil branches are connected in parallel between a second conductor (7a') and another second conductor (7b'), and the second current reference is set or reduced depending on the number and / or location of n2 and / or m2 and / or faulty coils. The method according to any one of claims 1 to 11.

13. A generator system (1), A generator (2) having a stator (3) having at least one polyphase winding set (4_1, 4_2), wherein the winding set comprises, for each phase, a plurality of coils (5_1, 5_1*, 5_1, 16_1) arranged in the inter-tooth slots of the stator and connected in particular in series and / or in parallel, wherein at least one of the plurality of coils (5_1*) is faulty and electrically isolated from a first conductor (7a) and other first conductors (7b), A control device (8) is adapted to operate the generator (2) without using the faulty coil (5_1*), thereby holding the faulty coil, which has been specifically disconnected, in a predetermined position on the stator. A generator system (1) is provided with the following:

14. A wind turbine (10), A hub (11) having multiple rotor blades (12) mounted on top, The generator system (1) according to claim 13, The generator rotor (6) is coupled to the hub (11) and A wind turbine (10) is equipped with this.

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