Method for determining the location of a short circuit fault in a generator arrangement, generator arrangement, wind turbine, computer program and electronically readable medium

Abstract

Method for determining the location of a short circuit fault in a generator arrangement, generator arrangement, wind turbine, computer program and electronically readable medium Method for determining the location of a short circuit fault in a generator arrangement (1), wherein the generator arrangement (1) comprises an electric machine (2) and at least one channel (3, 4), wherein the channel or each channel (3, 4) comprises a circuit breaker (6, 8), a converter unit (5, 7) and a set (9, 10) of stator windings of the electric machine (2) connected to the converter unit (5, 7) via the circuit breaker (6, 8). ), wherein, when a short circuit occurs in a channel (3, 4), the connection between the set of stator windings (9, 10) and the converter unit (5, 7) is interrupted by opening the circuit breaker (6, 8), wherein, depending on at least one measured signal (17) of a measured object, wherein the measured signal (17) is measured by at least one sensor (14) of the electric machine (2), and wherein the measured object describes a torque fluctuation of the electric machine (2), the electric machine (2) or the converter unit (5, 7) of the channel (3, 4) is determined as the location of the short circuit fault.

Description

[0001] The invention relates to a method for determining the location of a short circuit fault in a generator arrangement, wherein the generator arrangement comprises an electrical machine and at least one channel, wherein the or each channel comprises a circuit breaker, a converter unit and a set of stator windings of the electrical machine connected to the converter unit via the circuit breaker, wherein, in the event of a short circuit in the channel, the connection between the set of stator windings and the converter unit is interrupted by opening the circuit breaker. Furthermore, the invention relates to a generator arrangement, a wind turbine, a computer program and an electronically readable medium.

[0002] In such a generator arrangement, a short circuit fault may occur in different components of the arrangement. Typically, a short circuit fault causes a high current that exceeds the current during normal operation of the generator arrangement. It is known to use fuses or circuit breakers to detect and stop such short circuit currents in the circuit. However, the high current occurs independently of the location of the short circuit fault in the circuit of the generator arrangement. Therefore, when a short circuit fault occurs in a channel of the generator arrangement, only the faulty channel can be identified.

[0003] Therefore, it is desirable that when a short-circuit fault occurs in a circuit, detailed information about the short-circuit fault can be obtained.

[0004] It is therefore an object of the present invention to provide a method for determining the location of a short-circuit fault which gives more precise information about the location of the short-circuit fault.

[0005] According to the invention, this problem is solved by the method described initially, wherein, based on at least one measured signal of a measurand, wherein the measured signal is measured by at least one sensor of the electrical machine and wherein the measurand describes a torque ripple of the electrical machine, the location of a short-circuit fault in a converter unit of an electrical machine or a channel is determined.

[0006] In the event of a short-circuit fault in a channel of an electrical machine, not only can the faulty channel be detected by the open circuit breaker, but also the determination of whether the short-circuit fault occurred in the converter unit of the channel or in the electrical machine is possible by evaluating the measured object or at least one measured signal of the measured object, respectively. Thus, different sources of the short-circuit fault can be distinguished by evaluating the measured object.

[0007] This has the advantage that after a short circuit fault occurs, the faulty component can be identified, facilitating repair by providing the location of the faulty component that must be repaired or replaced.

[0008] In a preferred embodiment of the invention, the electric machine comprises two or more channels, wherein, after a short-circuit fault occurs in a channel, the converter unit of the channel is stopped and at least one circuit breaker of the channel is opened, or the converter units of all channels are stopped and the circuit breakers of all channels are opened. Opening the circuit breakers stops the large short-circuit current in the channel. It is particularly possible that the circuit breakers comprise one circuit breaker for each phase of the channel, or that multi-phase circuit breakers are used, such as three-phase circuit breakers for a three-phase channel, so that each stator winding in the set of stator windings is separated from the converter unit.

[0009] In the case where only the converter unit of the faulty channel in which the short circuit fault occurs is stopped and the circuit breaker of the faulty channel is disconnected, the remaining channels of the electric machine can be used to stop the rotation of the electric machine or its rotor, respectively. It is also possible to disconnect all the circuit breakers in all channels of the electric machine and stop all the converter units. In this case, for example, using a mechanical brake (brake) or the like, the rotation of the rotor of the electric machine can be stopped.

[0010] Preferably, the electric machine comprises two or more channels, wherein after a short circuit fault occurs in a faulty channel of the channels, if a converter unit is determined as a position, the operation of the generator arrangement is continued or restarted with one or more channels other than the faulty channel, wherein if the electric machine is determined as a position, the operation is stopped. In the event of a short circuit fault in one of the converter units of the channels, the continuation of the operation of the electric machine or the restart of the operation of the generator arrangement enables the use of the generator arrangement for a time period until the faulty converter unit can be repaired or replaced. In the event of a short circuit fault in the electric machine, the continuation of the operation of the generator arrangement is too dangerous because the short circuit in the electric machine may cause severe damage to the electric machine or to the generator arrangement when the operation is continued, so that in this case the operation is stopped and the restart of the operation of the generator arrangement may be prevented.

[0011] In a generator arrangement with an electrical machine comprising more than one channel, if the converter unit of the channel causing the fault has been determined as the location of the short-circuit fault, only the faulty channel may remain disconnected. Other channels of the electrical machine comprising converter units that are still functioning properly may be used to continue the operation of the generator arrangement. In this case, it is possible to continue the operation of the generator arrangement and prevent a shutdown of the entire generator arrangement.

[0012] However, in case a short circuit fault occurs in an electric machine of the generator arrangement, further operation of the entire generator arrangement should not take place, since a short circuit fault in the electric machine may cause damage to the electric machine or to other components of the generator arrangement, respectively. Therefore, if the electric machine is determined as the location of the short circuit fault, further operation of the generator arrangement may be prevented.

[0013] Having the ability to continue the operation of a generator arrangement comprising more than one channel is particularly advantageous for a generator arrangement being part of a facility for generating electrical energy such as a wind turbine or the like. In this case, a short circuit fault in a converter unit of one channel does not cause a stop of the entire facility until the faulty component is repaired.

[0014] The electric machine may in particular be an electric machine with a multiphase stator, which comprises several sets of stator windings, each connected to a separate converter unit. One or more sets of stator windings may be three-phase stator windings, generating a three-phase current in the stator during operation of the electric machine as a generator or rotation of the rotor, respectively. In particular, the rotor may comprise permanent magnets or rotor coils, which also generate a magnetic field after a short-circuit fault occurs.

[0015] Due to the magnetic coupling between the rotating rotor and the stator of the electrical machine, torque fluctuations in the torque of the electrical machine can occur after a short circuit fault occurs. The torque fluctuations are measured by at least one sensor of the electrical machine, wherein the sensor quantifies at least one measurand, which describes the torque fluctuations of the electrical machine. As measurand, a physical quantity that is affected by the torque fluctuations of the electrical machine can be used. The measurand can, for example, show fluctuations that correspond to the torque fluctuations of the electrical machine and / or are proportional to the torque fluctuations of the electrical machine.

[0016] The torque ripples of the electrical machine are different for short circuits, depending on whether they occur in the converter unit or in the generator. Therefore, by evaluating the torque ripples of the electrical machine, a determination of the location of the short circuit fault becomes possible.

[0017] In the event of a short circuit of the channel, the connection between the set of stator windings and the converter unit is interrupted by opening a circuit breaker. The circuit breaker may comprise, for example, a switch coupled to a current sensor. Preferably, the circuit breaker is a circuit breaker which interrupts the connection between the converter unit and the set of stator windings when a short circuit or a large short circuit current occurs. Preferably, the converter unit is also stopped in the event of a short circuit, for example by switching it off or by stopping its operation, respectively.

[0018] However, the short circuit fault may have occurred in the converter unit or in the generator. For example, a short circuit fault in the converter unit may occur due to a faulty component in the converter. A short circuit fault in the generator may occur, for example, due to insulation breakdown inside the electric machine. However, independently of the location of the short circuit, the connection between the converter unit and the set of stator windings is interrupted in order to stop the large short circuit current.

[0019] After interrupting the connection between the converter unit and the set of stator windings, the high short-circuit current flow between the converter and the machine in the faulty channel stops. Despite the short-circuit fault, the behavior of the generator arrangement does not depend on the location of the short-circuit fault before opening the circuit breaker. However, after interrupting the connection between the converter unit and the set of stator windings, the rotor of the electric machine still rotates and the behavior of the generator arrangement differs depending on the location of the short-circuit fault.

[0020] If the short-circuit fault is caused by a fault inside the converter unit, the current in the channel will drop to zero because the switching of the converter unit stops and the connection between the converter unit and the set of stator windings is interrupted. If the short-circuit fault is caused by an internal fault in the electric machine, even after the interruption of the connection between the converter unit and the set of stator windings, the magnetic coupling of the electromotive force (electromotvie force) (back EMF) in the windings of the electric machine will generate a fault current in the electric machine until the rotation of the rotor stops. In the event of a short-circuit fault in the set of stator windings, even after the disconnection of the circuit breaker, the closed loop remains due to the short circuit. In this closed loop, the rotating rotor of the electric machine induces a fault current. However, such a fault current cannot be measured directly. The present invention is based on the idea to indirectly measure such a fault current by evaluating the measured signal of the object under test, which describes the torque fluctuation of the electric machine, because the presence of the fault current affects the torque fluctuation of the electric machine. Therefore, by evaluating at least one measured signal of the object under test related to the torque fluctuation of the electric machine, it becomes possible to determine the location of the short circuit.

[0021] Preferably, as at least one sensor of the electric machine, a sensor is used which measures the vibration and / or acceleration of at least one component of the electric machine. By measuring the vibration of at least one component of the electric machine by the sensor, the measured object can be, for example, a periodic displacement of at least one component of the electric machine. The displacement can correspond to a torque fluctuation, since a larger torque fluctuation of the electric machine can cause a larger vibration of at least one component of the electric machine. In addition or alternatively, it is possible to use a sensor which measures the acceleration of at least one component of the electric machine, wherein correspondingly a larger torque fluctuation of the electric machine can cause a larger acceleration fluctuation amplitude of at least one component of the electric machine.

[0022] In a preferred embodiment of the invention, an accelerometer coupled to a main bearing of the electric machine and / or to at least one stator plate of the electric machine is used as a sensor, and / or a microphone measuring sounds inside the electric machine is used as a sensor, and / or a short-circuit torque controller is used as a sensor. The main bearing may be arranged between the rotor and the stator of the electric machine to support the rotating rotor against the stator, so that torque fluctuations of the electric machine cause vibrations or periodic deflections of the main bearing or a component of the main bearing, which may be measured by an accelerometer coupled to the main bearing. The sensor may, for example, be coupled to a stationary ring of the main bearing. It is possible to use sensors provided for monitoring the bearing condition.

[0023] It is also possible to use an accelerometer coupled to a stator plate.A stator plate is an annular flat plate which delimits the stator towards the environment and which can vibrate and / or exhibit displacements depending on the torque fluctuations of the electric machine.

[0024] In addition or alternatively, a microphone measuring the sound inside the electric machine can be used as a sensor, since the occurrence of torque fluctuations in the electric machine can cause sound to be generated into the air and / or as mechanical vibrations inside the electric machine. It is also possible that a short-circuit torque controller is used as a sensor, wherein the short-circuit torque controller can be configured to reduce the occurrence of torque fluctuations during a short circuit in the electric machine to minimize noise generation and prevent damage to the electric machine in the event of a short-circuit fault. Such a short-circuit torque controller includes a sensor that measures a measured object describing the torque fluctuations of the electric machine to apply countermeasures to reduce the torque fluctuations. Advantageously, the measured object measured by the short-circuit torque controller can also be used to determine the location of the short circuit.

[0025] Preferably, a comparison value associated with the amplitude of the torque fluctuation is derived from at least one measured signal of the measured object, wherein the comparison value is compared with a threshold value, wherein if the comparison value is above the threshold value, the electric machine is determined to be the location of a short circuit fault, and if the comparison value is below the threshold value, the converter unit is determined to be the location of a short circuit fault. The comparison value can be derived from one or more measured signals of the measured object, wherein at least one measured signal can in particular include measurements over a short period of time to describe the influence of the torque fluctuation on the measured object. Based on the at least one measured signal, the comparison value is derived and compared with the threshold value. A larger comparison value corresponds to a larger torque fluctuation, which occurs in the case of a short circuit fault in the electric machine as described above. Therefore, a comparison value above the threshold value indicates a short circuit in the electric machine and a comparison value below the threshold value indicates a short circuit in the converter unit. The threshold value for comparison with the comparison value can be a constant or a variable, and it can be derived from the measurement or it can be determined empirically. The threshold value can depend in particular on the type of electric machine and / or the type of generator arrangement or the installation in which the generator arrangement is used.

[0026] Preferably, the RMS value or the peak-to-peak value of the measured signal is used as the comparison value, or the absolute value of the measured signal is used. The RMS value and / or the peak-to-peak value can be used to describe the periodic component of the measured signal of the measured object corresponding to the torque fluctuation of the electrical machine or the amplitude of the periodic signal, respectively. Due to the rotation of the rotor, the torque fluctuation can also show a periodicity, in particular a periodicity corresponding to the rotation speed of the rotor. As an absolute value, for example, the average value or the maximum value within the average period of the measured signal can be used.

[0027] In a preferred embodiment of the invention, the threshold value is determined depending on the average torque of the electric machine and / or the rotational speed of the electric machine. The determination of the threshold value depending on the average torque of the electric machine can take into account the fact that a larger operating torque of the electric machine may cause larger torque fluctuations in the event of a short-circuit fault. The average torque after disconnecting the circuit breaker can be used in particular in a multi-channel generator comprising two or more sets of stator windings. Since the amplitude of the torque fluctuations may also depend on the frequency of rotation, the dependence of the threshold value on the rotational speed of the electric machine may also be advantageous. The rotational speed of the electric machine and / or the average torque of the electric machine can be determined, for example, by a torque sensor and / or a rotation sensor of the electric machine and / or a speed observer unit implemented in an operating channel of the multi-channel machine, respectively, in particular when a short-circuit fault occurs or in a time interval shortly after the short-circuit fault occurs, so that the location of the short-circuit fault can be determined taking into account the current state of the machine.

[0028] In particular, even if a stop of the wind turbine operation is triggered when a short circuit occurs, the implementation of the described method is feasible in a wind turbine, since short circuit detection and circuit breaker opening are typically completed in the ms range (below 300 ms), while turbine stopping takes several seconds (above 10 s). Therefore, a sufficient time window between circuit breaker opening and turbine stopping is available for fault identification.

[0029] Preferably, at least one measured signal of the measured object is bandpass filtered, wherein the lower cut-off frequency and / or the upper cut-off frequency of the bandpass filtering are determined according to the rotation speed of the electrical machine. By bandpass filtering the measured signal of the measured object, a certain frequency or a certain frequency band corresponding to the passband of the bandpass filter can be extracted to evaluate the measured object. By determining the lower cut-off frequency and / or the upper cut-off frequency of the bandpass filtering, it is possible to filter the measured signal so that a measured signal corresponding to a certain harmonic of the torque fluctuation can be obtained. For example, it is possible to extract the torque fluctuation at a frequency that is twice the frequency of the rotation of the electrical machine. Other harmonics, such as the fourth harmonic or the sixth harmonic, can also be extracted using bandpass filtering and the determination of the lower cut-off frequency and the upper cut-off frequency according to the rotation speed of the electrical machine. The selection of different harmonics of the torque fluctuation can take into account different geometries and / or characteristics of the electrical machine and can depend on the type of electrical machine used in the generator arrangement.

[0030] A generator arrangement according to the invention comprises an electric machine, a control unit and at least one channel, wherein the or each channel comprises a circuit breaker, a converter unit and a set of stator windings of the electric machine connected to the converter unit via the circuit breaker, wherein the electric machine comprises at least one sensor measuring a measurand describing torque ripples of the electric machine, wherein the control unit is configured to perform the method according to the invention.

[0031] Preferably, the electric machine may comprise two or more channels, which may be, for example, three-phase channels, each three-phase channel comprising a set of three phases of a stator winding. The control unit may be connected to a converter unit and / or a circuit breaker. The control unit is connected to at least one sensor measuring the object being measured. Furthermore, the control unit may be connected to further sensors of the electric machine, wherein the further sensors measure, for example, an average torque of the electric machine and / or a rotational speed of the electric machine. Additionally or alternatively, it is possible that the average torque of the electric machine and / or the rotational speed of the electric machine may be calculated and / or estimated by the control unit, for example by evaluating a current and / or a voltage of the electric machine.

[0032] A wind turbine according to the invention comprises an electric power generating machine arrangement according to the invention.

[0033] The computer program according to the invention comprises instructions which, when executed by a control unit of a generator arrangement comprising an electric machine, a control unit and at least one channel, cause the control unit to perform the method according to the invention, wherein the or each channel comprises means for detecting the occurrence of a short circuit in the channel, a converter unit and a set of stator windings of the electric machine connected to the converter unit, wherein the electric machine comprises at least one sensor measuring a measurand describing torque ripples of the electric machine.

[0034] An electronically readable medium according to the invention has stored thereon a computer program according to the invention.

[0035] All features and advantages described with respect to the method according to the invention apply correspondingly to the generator arrangement according to the invention, to the wind turbine according to the invention, to the computer program according to the invention and to the electronically readable medium according to the invention.

[0036] Additional advantages and details of the invention become apparent from the embodiments discussed below and from the accompanying drawings. The drawings are schematic and show:

[0037] Figure 1 According to the generator arrangement of the invention,

[0038] Figure 2 a diagram depicting the torque of an electric machine in the event of a short-circuit fault in a converter unit,

[0039] Figure 3 a diagram depicting the torque of an electric machine in the event of a short circuit fault in the electric machine,

[0040] Figure 4 a block diagram of a first embodiment of the method according to the invention, and

[0041] Figure 5 Block diagram of a second embodiment of the method according to the invention.

[0042] exist Figure 1 In FIG. 1 , a generator arrangement 1 according to the invention is shown. The generator arrangement 1 comprises an electric machine 2, a first channel 3 and a second channel 4. The first channel 3 comprises a converter unit 5 and a circuit breaker 6. Correspondingly, the second channel 4 comprises a converter unit 7 and a circuit breaker 8.

[0043] The converter unit 5 of the first channel 3 is connected to a set 9 of stator windings of the electric machine 2 via a circuit breaker 6. Correspondingly, the second channel 4 comprises a set 10 of stator windings connected to a control unit 7 via a circuit breaker 8. The sets 9, 10 of stator windings are three-phase sets of stator windings. During the rotation of the electric machine 2, and therefore during the generator operation of the electric machine 2, a three-phase current is generated in each of the channels 3, 4. The generated three-phase current is converted into a DC current by the converter units 5, 7. The DC side of the converter units 5, 7 can be connected to other electrical components and / or circuits and / or a power grid. In this embodiment, at the DC side of the converter 5, 7 of each channel 3, 4, capacitors 11, 12 are arranged for frequency filtering. However, in Figure 1 Further components on the DC side are omitted. It is in particular possible that the generator arrangement 1 is used in a power generation plant, for example in a wind turbine.

[0044] The circuit breaker 6 in the first channel 3 can be opened to interrupt the connection between the converter unit 5 and the set of stator windings 9 in case of a short circuit in the first channel 3. Correspondingly, the circuit breaker 8 in the second channel 4 can be opened to interrupt the connection between the converter unit 7 and the set of stator windings 10 in case of a short circuit in the second channel 4. Preferably, the circuit breakers 6 and 8 can interrupt their respective connections simultaneously in case of a short circuit in one of the channels 3, 4.

[0045] The generator arrangement 1 further comprises a control unit 13 connected to the converter units 5, 7 and the circuit breakers 6, 8. Furthermore, the control unit 13 is connected to sensors 14 of the electric machine 2, wherein the sensors 14 measure a measurand describing a torque ripple of the electric machine 2. The control unit 13 comprises a memory unit for storing data and / or programs, a communication unit for sending and receiving data and a processor unit for processing data and / or for executing programs and / or for controlling the communication unit.

[0046] In this embodiment, the sensor 14 is an accelerometer coupled to the main bearing of the electric machine 2. Via the sensor 14, vibrations caused by the occurrence of torque fluctuations in the electric machine 2 can be measured, because the vibrations measurable by the sensor 14 in the main bearing correspond to the torque fluctuations of the electric machine 2. Additionally or alternatively, an accelerometer coupled to at least one stator plate of the electric machine 2 and / or a microphone measuring sounds inside the electric machine 2 and / or a short-circuit torque controller can also be used as the sensor 14.

[0047] If a short circuit occurs, for example, in the first channel 3, the circuit breaker 6 is opened to stop the short circuit current in the first channel 3. The opening of the circuit breaker 6 can be detected and / or commanded, for example, by the control unit 13. The operation of the converter unit 5 can be stopped by the control unit 13. The short circuit in the channel 3 can occur in the converter unit 5, for example due to a faulty component in the converter unit 5. The following is also possible: the short circuit fault occurs in the electric machine 2, for example due to insulation breakdown inside the electric machine 2 and / or in the set 9 of stator windings. Depending on the location where the short circuit fault occurs, different behaviors with respect to the torque fluctuation of the electric machine 2 occur. Since the electric machine 2 is in operation when the short circuit fault occurs, the rotor of the electric machine 2 is rotating. The rotor includes means for generating a magnetic field, for example a plurality of permanent magnets, so that after a short circuit fault occurs in the electric machine 2, a current can be generated in the electric machine 2 due to the magnetization of the rotor. In this case, the fault current flows in the set 9 of stator windings.

[0048] In case of a short circuit fault in the converter unit 5 , no fault current is generated because the connection between the converter unit 5 and / or the stator windings of the set 9 of stator windings is disrupted by opening the circuit breaker 6 and switching in the converter unit 5 is stopped.

[0049] The fault current in the electric machine 2 causes torque ripples in the torque of the electric machine 2. Since the fault current in the electric machine 2 cannot be measured directly, the measurement of the torque ripples can be used as an indirect measurement of the fault current. The torque ripples can be measured, for example, by a sensor 14 that measures vibrations in the main bearings of the electric machine 2, because if torque ripples occur or increase in the torque of the electric machine 2, vibrations of the main bearings of the electric machine 2 may also occur or increase, respectively.

[0050] exist Figure 2 In FIG. 5 , a diagram is shown which depicts the torque of an electric machine 2 . On the ordinate, the torque M is plotted, depending on the time t which is plotted on the abscissa. At time t f At , a short circuit fault occurs in channel 3 of the generator arrangement 1. After a few initial peaks, a discernible torque ripple builds up in the portion 15 of the curve. Figure 2 The curve in φ depicts the torque of the electric machine 2 in the event of a short-circuit fault in the converter unit 5 of the channel 3. The average torque after the short-circuit fault has occurred is reduced to approximately half of the value before the fault.

[0051] exist Figure 3 In FIG. 1 , a curve of the torque M of the electric machine 2 is depicted for a short circuit fault in the electric machine 2. The short circuit fault is correspondingly generated at t f However, in the event of a short circuit fault in the electric machine 2, the amplitude of the torque fluctuation in the portion 16 of the curve appears to be greater than in the case of Figure 2 Due to the different amplitudes of the torque ripples of the torque of the electric machine 2 , a distinction between the electric machine 2 and the converter unit 5 of the first channel 3 as the location of the short-circuit fault is possible.

[0052] exist Figure 4 In FIG. 1 , a block diagram of a first embodiment of the method according to the invention is shown. As input variable, a measured signal 17 of a measured object describing the torque fluctuation of the electric machine 2 is used. The measured signal 17 can be measured by a sensor 14 of the electric machine 2. The measured object can be, for example, an acceleration measured by the sensor 14 at a stationary ring of a main bearing of the electric machine 2.

[0053] In box 18, a low pass filtering to eliminate the DC offset of the measured signal 17 takes place. After the low pass filtering, the measured signal 17 is high pass filtered in box 19 to remove any HF noise. In box 20, the absolute value of the fluctuations in the measured signal 17 corresponding to the absolute value of the torque fluctuation amplitude is determined from the filtered measured signal 17. In box 21, after the absolute value of the fluctuations in the measured signal 17 is determined, a comparison value is determined by averaging the obtained absolute values ​​over a certain time interval or over an averaging window, respectively. The comparison value is related to the amplitude of the torque fluctuation or to the amplitude of the fluctuations in the measured signal 17 corresponding to the torque fluctuation, respectively.

[0054] In block 22, the comparison value is compared with a threshold value, wherein the threshold value may be a fixed value or may be determined based on the absolute torque or average torque of the electric machine 2. The absolute torque or average torque of the electric machine 2 may be measured by a torque sensor connected to the control unit 13, or it may be calculated and / or estimated by the control unit 13 based on the current and / or voltage in the electric machine 2 measured and / or controlled by the control unit 13. If the comparison value exceeds the threshold value, the electric machine 2 is selected as the location of the short-circuit fault. Conversely, if the comparison value is lower than or equal to the threshold value, the converter unit 4 of the first channel 3 is determined as the location of the short-circuit fault. The functionality of blocks 18 to 22 may be implemented in the control unit 13 of the generator arrangement 1.

[0055] exist Figure 5In FIG. 2 , a second embodiment of the method according to the invention is depicted. The method can be performed by a control unit 13 of a generator arrangement 1 . As input variable, a measured signal 17 measured by a sensor 14 is used again. In addition, a rotor speed signal 23 is used, which is measured by a rotor speed sensor (not shown) of the electric machine 2 or calculated and / or estimated by the control unit 13. In block 24, an adaptive bandpass filtering of the measured signal 17 takes place. Thereby, the lower cut-off frequency and / or the upper cut-off frequency of the bandpass filtering can be adjusted as a function of the rotor speed signal 23. By adjusting the lower cut-off frequency and / or the upper cut-off frequency of the bandpass filtering, certain harmonics of the rotation of the rotor can be filtered from the measured signal. It is possible, for example, to filter the second harmonic of the measured signal 17. It is also possible to filter the fourth or sixth harmonic of the measured signal 17, depending on the type of the electric machine 2. In addition or alternatively, the center frequency and / or the damping of the bandpass filtering can also be adjusted.

[0056] In block 25, a root mean square value is calculated from the measured signal 17 as a comparison value. In addition or alternatively to the root mean square value, the calculation of a peak-to-peak value of the measured signal 17 is also possible. The comparison value can be determined based on the rotor speed signal 23. The determined comparison value corresponds to the torque fluctuation of the electric machine 2. The comparison value determined in block 25 is compared with a threshold value in block 22, as described for the first embodiment of the method. It is possible that the threshold value for the comparison in block 22 is determined based on the average torque of the electric machine 2 and / or based on the rotor speed signal 23. The second embodiment of the method can also be implemented in the control unit 13.

[0057] In both embodiments of the method discussed hereinbefore, it is possible that, after determining the location of the short-circuit fault, if the converter unit 5 has been determined as the location of the short-circuit fault, a restart of the generator arrangement 1 using the second channel 4 is performed, in particular if the circuit breaker 8 was opened when the short-circuit fault occurred. It is also possible that, in the case where only the circuit breaker 6 of the first channel 3 has been opened, the operation of the generator arrangement 1 is continued using the second channel 4. However, if the electric machine 2 has been determined as the location of the short-circuit fault, the operation of the generator arrangement 1 is stopped.

[0058] The method is performed accordingly if the fault occurs in the second channel 4 and not in the first channel 3. In the case of an electrical machine comprising only one channel, the location of the short circuit fault can be stored, for example, in a storage device of the control unit 13, so that before repair of the generator arrangement 1, the location of the short circuit can be used to facilitate the repair.

[0059] If the method is applied in a generator arrangement comprising more than two channels, if the converter unit of a faulty channel is determined as the location of a short-circuit fault, operation can be continued using all channels except the faulty channel. Accordingly, if the electric machine 2 has been determined as the location of a short-circuit fault, operation of all channels of the generator arrangement 1 is prevented or stopped.

[0060] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the disclosed examples and a skilled person can derive other variations from the disclosed examples without departing from the scope of the present invention.

Claims

1. A method for determining the location of a short-circuit fault in a generator arrangement (1), wherein: The generator arrangement (1) comprises an electric machine (2) and at least one channel (3, 4), wherein the channel (3, 4) or each of the channels (3, 4) comprises a circuit breaker (6, 8), a converter unit (5, 7) and a set (9, 10) of stator windings of the electric machine (2) connected to the converter unit (5, 7) via the circuit breaker (6, 8), wherein in the event of a short circuit in the channel (3, 4), the connection between the set (9, 10) of stator windings and the converter unit (5, 7) is interrupted by opening the circuit breaker (6, 8), characterized in that, depending on at least one measured signal (17) of a measured object, the measured signal (17) is measured by at least one sensor (14) of the electric machine (2), and wherein the measured object describes a torque fluctuation of the electric machine (2), the electric machine (2) or the converter unit (5, 7) of the channel (3, 4) being determined as the location of the short circuit fault.

2. The method according to claim 1, characterized in that: As the at least one sensor (14) of the electric machine (2), a sensor is used which measures the vibration and / or acceleration of at least one component of the electric machine (2).

3. The method according to claim 2, characterized in that An accelerometer coupled to a main bearing of the electric machine (2) and / or to at least one stator plate of the electric machine (2) is used as a sensor, and / or a microphone for measuring sounds inside the electric machine (2) is used as a sensor, and / or a short-circuit torque controller is used as a sensor.

4. The method according to any one of the preceding claims, characterized in that A comparison value related to the amplitude of the torque fluctuation is derived from the at least one measured signal (17) of the measured object, wherein the comparison value is compared with a threshold value, wherein if the comparison value is above the threshold value, the electric machine (2) is determined as the location of the short-circuit fault, and if the comparison value is below the threshold value, the converter unit (5, 7) is determined as the location of the short-circuit fault.

5. The method according to claim 4, characterized in that The root mean square value of the measured signal or the peak-to-peak value of the measured signal (17) or the absolute value of the measured signal (17) is used as comparison value.

6. The method according to claim 4, characterized in that The threshold value is determined based on an average torque of the electric machine (2) and / or a rotational speed of the electric machine (2).

7. The method according to claim 4, characterized in that The at least one measured signal of the measured object is band-pass filtered, wherein a lower cut-off frequency and / or an upper cut-off frequency of the band-pass filter is determined as a function of the rotational speed of the electric machine (2).

8. The method according to claim 4, characterized in that The electric machine (2) comprises two or more channels (3, 4), wherein, after the short circuit fault occurs in a channel (3, 4), the converter unit (5, 7) of the channel (3, 4) is stopped and the at least one circuit breaker (6, 8) of the channel (3, 4) is opened, or the converter units (5, 7) of all channels (3, 4) are stopped and the circuit breakers (6, 8) of all channels (3, 4) are opened.

9. The method according to claim 4, characterized in that The electric machine (2) comprises two or more channels (3, 4), wherein, after the short circuit fault occurs in a faulty channel of the channels (3, 4), if the converter unit (5, 7) is determined to be in position, the operation of the generator arrangement (1) is continued or restarted using the one or more channels other than the faulty channel, wherein if the electric machine (2) is determined to be in position, the operation is stopped.

10. A generator arrangement (1) comprising an electric machine (2), a control unit (13) and at least one channel (3, 4), wherein: The channel (3, 4) or each of the channels (3, 4) comprises means for detecting the occurrence of a short circuit in the channel (3, 4), a converter unit (5, 7) and a set (9, 10) of stator windings of the electric machine (2) connected to the converter unit (5, 7), wherein the electric machine (2) comprises at least one sensor (14) measuring a measurand describing torque ripples of the electric machine (2), wherein the control unit (13) is configured to carry out a method according to one of the preceding claims.

11. A wind turbine comprising a generator arrangement according to claim 10.

12. A computer program product comprising instructions which, when executed by a control unit of a generator arrangement (1) comprising an electric machine (2), a control unit (13) and at least one channel (3, 4), cause the control unit to perform a method according to one of claims 1 to 9, wherein: The channel (3, 4) or each of the channels (3, 4) comprises means for detecting the occurrence of a short circuit in the channel (3, 4), a converter unit (5, 7) and a set (9, 10) of stator windings of the electric machine (2) connected to the converter unit (5, 7), wherein the electric machine (2) comprises at least one sensor (14) measuring a measurand describing a torque ripple of the electric machine (2).

13. An electronically readable medium having stored thereon a computer program product according to claim 12.

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