Short-circuit detection device and method for a rotating electric machine

Abstract

The short-circuit detection device for a rotating electric machine includes a signal acquisition unit, a signal decomposition unit, a specific frequency component reduction unit, a signal conversion unit, a short-circuit detection unit, and an estimation accuracy determination unit. The signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into multiple frequency components of different orders. The specific frequency component reduction unit uses a threshold number lower than the fundamental order of the higher harmonics of the slot as a threshold, reducing the odd-order frequency components and the even-order frequency components above the threshold. The signal conversion unit converts the multiple frequency components output from the specific frequency component reduction unit into a voltage signal. The short-circuit detection unit generates a difference waveform of each voltage signal corresponding to an adjacent magnetic pole, detects a short circuit in the excitation winding based on the shape of the difference waveform, and estimates the short-circuit location of the excitation winding. The estimation accuracy determination unit determines the estimation accuracy of the short-circuit location of the excitation winding based on the symmetry of the maximum wave centered at the peak angle of the difference waveform.

Description

Technical Field

[0001] This disclosure relates to a short-circuit detection device and a short-circuit detection method for rotating electrical machines. Background Technology

[0002] In conventional rotating electrical machines, changes in excitation flux caused by a short circuit in the rotor's excitation winding are detected by a detection coil. The detection coil is fixed to the stator in the gap between the rotor and the stator. When no short circuit occurs in the excitation winding, the detection coil detects only the flux at odd-order frequencies. Conversely, when a short circuit occurs in the excitation winding, the detection coil detects both the flux at odd-order and even-order frequencies (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 53-84101 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, in conventional rotating electric machines, there is a problem that it is difficult to determine at which position of the excitation winding in the rotor it is short-circuited.

[0008] This disclosure was made to solve the aforementioned problems, and its purpose is to provide a short-circuit detection device and method for a rotating electric motor capable of estimating the location of a short circuit in the circumferential direction of the excitation winding.

[0009] Solution for solving the problem

[0010] This disclosure discloses a short-circuit detection device for a rotating electric machine, comprising: a signal acquisition unit that acquires a voltage signal from a magnetic detector facing an excitation winding disposed in a plurality of slots of an excitation element; a signal decomposition unit that decomposes the voltage signal acquired by the signal acquisition unit into a plurality of frequency components of different orders; a specific frequency component reduction unit that uses a threshold number lower than the fundamental order of a higher harmonic related to the spacing of the plurality of slots (i.e., the slot higher harmonic) and reduces the odd-order frequency components and the even-order frequency components above the threshold number among the plurality of frequency components; a signal conversion unit that converts the plurality of frequency components output from the specific frequency component reduction unit into a voltage signal; and a short-circuit detection unit that detects the voltage signal from the signal conversion unit. The converted voltage signal is divided according to the circumferential angle of the excitation element corresponding to the multiple magnetic poles of the excitation element, generating a difference waveform of each voltage signal corresponding to an adjacent magnetic pole among the multiple magnetic poles. Based on the shape of the difference waveform, a short circuit in the excitation winding is detected, and the location of the short circuit in the excitation winding in the circumferential direction of the excitation element is estimated. The estimation accuracy determination unit determines the estimation accuracy of the location of the short circuit. In the difference waveform, when the wave with the maximum value including the absolute value of the peak voltage is set as the maximum wave, and the circumferential angle of the excitation element corresponding to the maximum value is set as the peak angle, the estimation accuracy determination unit determines the estimation accuracy of the location of the short circuit based on the symmetry of the maximum wave waveform centered on the peak angle.

[0011] This disclosure discloses a short-circuit detection method for a rotating electric machine, comprising: a signal acquisition step, acquiring a voltage signal from a magnetic detector facing an excitation winding disposed in a plurality of slots of an excitation element; a signal decomposition step, decomposing the voltage signal acquired in the signal acquisition step into a plurality of frequency components of different orders; a specific frequency component reduction step, using a threshold number lower than the fundamental order of a higher harmonic related to the spacing of the plurality of slots (i.e., the slot higher harmonic), and reducing the odd-order frequency components and the even-order frequency components above the threshold number among the plurality of frequency components; a signal conversion step, converting the plurality of frequency components processed by the specific frequency component reduction step into a voltage signal; and a short-circuit detection step, converting the voltage signal from the magnetic detector into a voltage signal. The voltage signal after signal conversion is segmented according to the circumferential angle of the exciter corresponding to the multiple magnetic poles of the exciter, generating a difference waveform of each voltage signal corresponding to an adjacent magnetic pole among the multiple magnetic poles. Based on the shape of the difference waveform, a short circuit in the exciter winding is detected, and the location of the short circuit in the exciter winding in the circumferential direction of the exciter is estimated. In the estimation accuracy determination step, the estimation accuracy of the location of the short circuit is determined. In the difference waveform, when the wave with the maximum absolute value of the peak voltage is set as the maximum wave, and the circumferential angle of the exciter corresponding to the maximum value is set as the peak angle, the estimation accuracy determination step determines the estimation accuracy of the location of the short circuit based on the symmetry of the maximum wave centered on the peak angle.

[0012] The effects of the invention

[0013] According to the short-circuit detection device and method for rotating electric machines disclosed herein, it is possible to determine at which position in the circumferential direction of the excitation winding the short circuit occurs. Attached Figure Description

[0014] Figure 1 This is a structural diagram showing the rotary electric motor and short-circuit detection device of Embodiment 1.

[0015] Figure 2 It means by Figure 1 A waveform diagram of an example of the voltage signal acquired by the signal acquisition unit.

[0016] Figure 3 It means by Figure 1 The spectrum of the amplitude component of the voltage signal after frequency analysis of the signal decomposition part.

[0017] Figure 4 It means through Figure 1 The specific frequency component decreases from Figure 3 The spectrum of the amplitude component after specific frequency components have been reduced.

[0018] Figure 5 It means by Figure 1 The diagram shows the voltage signal after conversion by the signal conversion unit.

[0019] Figure 6 It means to Figure 5 The voltage signal shown is input to Figure 1 The graph shows the difference waveform obtained from the short-circuit detection unit.

[0020] Figure 7 It means in relation to obtaining Figure 6 The figure shown is an example of the difference waveform obtained under different operating conditions of the turbine generator.

[0021] Figure 8 It means that the assumption will Figure 2 The voltage signal shown is directly input to Figure 1 The graph shows the difference waveform obtained under the condition of short-circuit detection unit.

[0022] Figure 9 Yes Figure 1 The flowchart shows the short-circuit detection routine executed by the short-circuit detection device.

[0023] Figure 10 It means based on Figure 1 The diagram shows other determination methods for the estimation accuracy determination section.

[0024] Figure 11 This is a structural diagram of a first example of a processing circuit that implements the functions of the short-circuit detection device for the rotating electric machine in embodiments 1 and 2.

[0025] Figure 12 This is a structural diagram of a second example of a processing circuit that implements the functions of the short-circuit detection device for the rotating electric machine in embodiments 1 and 2. Detailed Implementation

[0026] The embodiments will now be described with reference to the accompanying drawings.

[0027] Implementation Method 1

[0028] Figure 1 This is a structural diagram showing the rotary electric machine and short-circuit detection device according to Embodiment 1. In Embodiment 1, a turbine generator 10 is used as the rotary electric machine. Figure 1 In the diagram, a section perpendicular to the axial direction of the turbine generator 10 is shown for the turbine generator 10.

[0029] like Figure 1 As shown, the turbine generator 10 includes a stator 20 as an armature and a rotor 30 as an excitation element. The stator 20 has a cylindrical stator core 21 and multiphase windings 22. The stator 20 is disposed on the outside of the rotor 30.

[0030] The axial direction of the stator core 21 is along the axis of the stator core 21, and is perpendicular to it. Figure 1 The direction perpendicular to the paper surface. The radial direction of the stator core 21 is the radius of a circle centered on the axis of the stator core 21. The circumferential direction of the stator core 21 is along the arc of a circle centered on the axis of the stator core 21.

[0031] A plurality of stator slots 23 are formed on the inner periphery of the stator core 21. Each stator slot 23 is formed along the radial direction of the stator core 21. In addition, the plurality of stator slots 23 are arranged at equal intervals in the circumferential direction of the stator core 21. In Embodiment 1, the total number of stator slots 23 is 84. A multiphase winding 22 is wound in the plurality of stator slots 23.

[0032] The rotor 30 has a rotor core 31, an excitation winding 32, and a rotating shaft (not shown). The rotor core 31 and the rotating shaft are coaxially arranged with the stator core 21. The rotor 30 is capable of rotating about the rotating shaft.

[0033] The axial direction of rotor core 31 is along the axis O of rotor core 31, and is perpendicular to it. Figure 1 The direction perpendicular to the paper surface. The radial direction of the rotor core 31 is the radius of the circle centered on the axis O of the rotor core 31. The circumferential direction of the rotor core 31 is along the direction of the arc centered on the axis O of the rotor core 31.

[0034] Multiple rotor slots 33 are formed on the outer periphery of the rotor core 31. Each rotor slot 33 is formed along the radial direction of the rotor core 31.

[0035] In embodiment 1, the plurality of rotor slots 33 are divided into a first slot group 34 and a second slot group 35. Each of the first slot group 34 and the second slot group 35 includes 16 rotor slots 33. That is, the total number of rotor slots 33 is 32.

[0036] In the first slot group 34 and the second slot group 35, a plurality of rotor slots 33 are arranged at equal intervals along the circumference of the rotor core 31. The spacing of the rotor slots 33 is the distance between the centers of two adjacent rotor slots 33 in the width direction along the circumference of the rotor core 31. For the spacing of the rotor slots 33 in Embodiment 1, if expressed by the circumferential angle of the rotor core 31, it is 7.42°. Hereinafter, the spacing of each rotor slot 33 is referred to as the "rotor slot spacing".

[0037] A first magnetic pole 36 and a second magnetic pole 37 are formed between the first slot group 34 and the second slot group 35. Figure 1 In the diagram, the line below the dotted line passing through the axis O of rotor core 31, the center of the first magnetic pole 36 in the circumferential direction of rotor 30, and the center of the second magnetic pole 37 is referred to as the magnetic pole centerline C1. The first slot group 34 and the second slot group 35 are arranged symmetrically about the magnetic pole centerline C1.

[0038] In addition, the dotted line passing through the axis O of the rotor core 31, the center of the first slot group 34 and the center of the second slot group 35 in the circumferential direction of the rotor core 31 will be referred to as the inter-pole center line C2.

[0039] The multiple rotor slots 33 are respectively named as the first slot, the second slot, ..., the eighth slot, starting from the side closest to the magnetic pole center line C1. In other words, the multiple rotor slots 33 are respectively named as the first slot, the second slot, ..., the eighth slot, starting from the side furthest from the inter-pole center line C2.

[0040] In multiple rotor slots 33, the excitation winding 32 is wound back and forth between the first slot group 34 and the second slot group 35, separated by the magnetic pole center line C1. In the excitation winding 32, portions of adjacent rotor slots 33 are connected in series.

[0041] The excitation winding 32 is DC excited by an external power source (not shown). Thus, one of the first magnetic pole 36 and the second magnetic pole 37 becomes the N pole, and the other becomes the S pole. That is, the turbine generator 10 is a two-pole generator.

[0042] A gap 40 is formed between the stator core 21 and the rotor core 31. The multiphase winding 22 is AC-excited by an external power source (not shown). As a result, a rotating magnetic field is generated within the gap 40.

[0043] A detection coil 50, serving as a magnetic detector, is fixed on the stator core 21. More specifically, the detection coil 50 is fixed on the inner circumference of the stator core 21, facing the gap 40. Furthermore, the detection coil 50 faces the excitation winding 32.

[0044] The main magnetic flux and leakage magnetic flux are linked with the detection coil 50. The main magnetic flux is the magnetic flux generated in the gap 40, and the leakage magnetic flux is the magnetic flux leaking from each rotor slot 33. The magnetic flux linked with the detection coil 50 is called the linking magnetic flux.

[0045] The detection coil 50 has a first terminal 51 and a second terminal 52. When a magnetic flux links with the detection coil 50, a voltage signal is generated between the first terminal 51 and the second terminal 52. The distribution of the linking magnetic flux within the detection coil 50 changes as the rotor 30 rotates.

[0046] The short-circuit detection device 60 includes a signal acquisition unit 61, a signal decomposition unit 62, a specific frequency component reduction unit 63, a signal conversion unit 64, a short-circuit detection unit 65, and an estimated accuracy determination unit 66 as a functional module.

[0047] The signal acquisition unit 61 acquires the voltage signal generated by the detection coil 50. The signal decomposition unit 62 decomposes the voltage signal acquired by the signal acquisition unit 61 into multiple frequency components with different frequencies. Furthermore, the signal decomposition unit 62 separates each decomposed frequency component into amplitude and phase.

[0048] The specific frequency component reduction unit 63 sets the number of frequency components lower than the fundamental number of the slot higher harmonics as a threshold. The slot higher harmonics are higher harmonics related to the rotor slot spacing.

[0049] Furthermore, the specific frequency component reduction section 63 reduces the odd-order frequency components and the even-order frequency components above the threshold in the separated amplitude.

[0050] The signal conversion unit 64 converts the phase and the amplitude obtained by the specific frequency component reduction unit 63 into a voltage signal with reduced specific frequency components by accumulating the phase according to the number of frequency components.

[0051] The short-circuit detection unit 65 divides the voltage signal, after the conversion of specific frequency components, into segments according to the circumferential angles of the rotor 30 corresponding to the first magnetic pole 36 and the second magnetic pole 37 of the rotor 30, respectively. Furthermore, the short-circuit detection unit 65 generates a difference waveform for each voltage signal corresponding to the first magnetic pole 36 and the second magnetic pole 37. Based on the shape of the difference waveform, the short-circuit detection unit 65 detects a short circuit in the excitation winding 32 and estimates the location of the short circuit in the excitation winding 32 within the circumferential direction of the rotor 30.

[0052] The estimation accuracy determination unit 66 determines the estimation accuracy of the location where the excitation winding 32 has a short circuit. In addition, the estimation accuracy determination unit 66 outputs information to the display device 70 regarding whether the excitation winding 32 has a short circuit, the location of the rotor slot 33 where the short circuit has occurred, and the estimation accuracy of the rotor slot 33 where the short circuit has occurred.

[0053] The display device 70 is disposed outside the short circuit detection device 60. Based on information from the estimation accuracy determination unit 66, the display device 70 displays whether a short circuit has occurred in the excitation winding 32, the position of the rotor slot 33 where the short circuit occurred, and the estimation accuracy of the rotor slot 33 where the short circuit occurred.

[0054] Next, referring to the accompanying drawings, the functional modules of the short-circuit detection device 60 of Embodiment 1 will be described in more detail. Figure 2 It means by Figure 1 A waveform diagram of an example of a voltage signal acquired by the signal acquisition unit 61. This waveform diagram is simulated using an electromagnetic field analysis program. Figure 1 The simulation was obtained under the load operating conditions of the turbine generator 10. Additionally, for example, a simulation was performed in the second slot on the first magnetic pole 36 side, under conditions where the excitation winding 32 was short-circuited by one turn.

[0055] like Figure 2As shown, for example, circumferential angles from 0° to 180° correspond to the first magnetic pole 36, and circumferential angles from 180° to 360° correspond to the second magnetic pole 37. Therefore, at a circumferential angle of 90°, the center of the first magnetic pole 36 is closest to the detection coil 50, and at a circumferential angle of 270°, the center of the second magnetic pole 37 is closest to the detection coil 50. Figure 2 The 32 minute voltage variations occur at the rotor slot spacing, i.e., 7.42°.

[0056] Figure 3 It means by Figure 1 The signal decomposition unit 62 performed frequency analysis on the voltage signal, and the spectrum of the amplitude component is shown in the graph. The horizontal axis represents the order of the nth harmonic. Figure 3 The upper axis represents the higher harmonics up to the 110th order. n is an integer greater than or equal to 1. Furthermore, higher harmonics above the 111th order have small amplitudes and are therefore omitted from the display. The vertical axis represents the voltage intensity of each higher harmonic.

[0057] according to Figure 3 It is known that the voltage intensity of odd-order higher harmonics is greater than that of even-order higher harmonics. Odd-order higher harmonics are generated regardless of whether the excitation winding 32 is short-circuited. On the other hand, even-order higher harmonics are generated when the excitation winding 32 is short-circuited.

[0058] Furthermore, among the odd-order higher harmonics, the voltage intensity of the 1st and 47th higher harmonics is particularly large. The 1st higher harmonic is also called the fundamental frequency. The fundamental frequency is the frequency component of the main magnetic flux. Additionally, the 47th higher harmonic is the slot higher harmonic. Slot higher harmonics are higher harmonics related to the rotor slot spacing. The 47th is the fundamental order of the slot higher harmonics. The slot higher harmonics are generated by the difference between the 1st magnetomotive force in the rotor 30 and the change in permeability of the rotor slot spacing.

[0059] High-order harmonics above the 48th order are high-order harmonics corresponding to a spacing narrower than the rotor slot spacing, i.e., an angle smaller than the rotor slot spacing in the circumferential direction. Frequency components corresponding to angles smaller than the rotor slot spacing are not the components needed to estimate the short-circuit location of the excitation winding 32. Therefore, the specific frequency component reduction unit 63 selects a frequency less than 47 as the threshold for removing even-order frequency components. Then, the specific frequency component reduction unit 63 removes all even-order frequency components greater than the selected threshold.

[0060] The voltage intensity of higher harmonics in the slot is higher than that of odd-order frequency components close to the higher harmonics. Therefore, even-order frequency components closer to the higher harmonics in the slot are more susceptible to the influence of the higher harmonics and become unstable. Therefore, it is more preferable to set a threshold to remove even-order frequency components that are susceptible to the influence of higher harmonics in the slot.

[0061] Furthermore, odd-order frequency components are a major obstacle to detecting even-order frequency components. On the other hand, odd-order frequency components contain information needed to determine the circumferential angle. Therefore, in order to estimate the short-circuit location of the excitation winding 32, it is undesirable to completely remove them. Therefore, the specific frequency component reduction section 63 does not remove all odd-order frequency components but attenuates them.

[0062] More specifically, in Embodiment 1, the specific frequency component reduction unit 63 sets the threshold to 12 and removes even-numbered frequency components of 14 or higher. Furthermore, the specific frequency component reduction unit 63 attenuates all odd-numbered frequency components to 1 / 50. Thus, in this embodiment, reducing frequency components includes both removing frequency components and attenuating them.

[0063] Figure 4 It means through Figure 1 The specific frequency component reduction part 63 from Figure 3 The spectrum of the amplitude component after specific frequency components have been reduced. For example... Figure 4 As shown, the spectrum of the amplitude component output from the specific frequency component reduction section 63 includes even frequency components from the 2nd to the 12th order and attenuated odd frequency components.

[0064] This reduces the main obstacles to detecting whether a short circuit has occurred in the excitation winding 32. Consequently, it improves the accuracy of short circuit detection.

[0065] Figure 5 It means by Figure 1 The diagram shows the voltage signal converted by the signal conversion unit 64. Since the converted voltage signal does not include the slot higher harmonics component, it is related to... Figure 2 A comparison shows that, in Figure 5 In this case, the voltage fluctuation period becomes longer. In other words, in Figure 5 In the process, no fine waveforms of rotor slot spacing were observed.

[0066] Figure 6 It means to Figure 5 The voltage signal shown is input to Figure 1 The graph shows the difference waveform obtained by the short-circuit detection unit 65. Since the polarities of the first magnetic pole 36 and the second magnetic pole 37 are different, in order to obtain the difference waveform, it is only necessary to add the waveform from 0° to 180° corresponding to the first magnetic pole 36 and the waveform from 180° to 360° corresponding to the second magnetic pole 37. Figure 5 The waveform shown is divided into left and right segments and then added together to obtain... Figure 6 The difference waveform is shown.

[0067] exist Figure 6In the difference waveform, a positive peak voltage appears at 50° and a negative peak voltage appears at 130°. The absolute value of the positive peak voltage is greater than the absolute value of the negative peak voltage. Therefore, the maximum absolute value of the peak voltage in the difference waveform is the same as the absolute value of the positive peak voltage. The wave that includes this maximum value is called the maximum wave.

[0068] Additionally, "a wave" refers to the range from the circumferential angle where the absolute value of the voltage is smallest on one side of the peak voltage to the circumferential angle where the absolute value of the voltage is smallest on the other side of the peak voltage.

[0069] Figure 6 The vertical dashed lines represent the circumferential angles from the first to the eighth slot. The dashed line closest to 90°, corresponding to the center of the magnetic pole, is the first slot, and the dashed lines closest to 0° and 180° are the eighth slot. The spacing between adjacent dashed lines corresponds to the rotor slot spacing.

[0070] The half-width of a wave including both the positive and negative peak voltages is greater than the rotor slot spacing. The half-width is the circumferential angular range of a wave in the half-value voltage, which serves as the determining voltage. The half-value voltage is half the peak voltage.

[0071] Thus, the appearance of a peak waveform wider than the rotor slot spacing indicates that the excitation winding 32 has short-circuited.

[0072] The peak voltages at 50° and 130° are both closest to the dashed line representing the second slot. Based on this result, the short-circuit detection unit 65 estimates that a short circuit has occurred in the excitation winding 32 in the second slot.

[0073] The estimation accuracy determination unit 66 determines the estimation accuracy of the location of the short circuit based on the symmetry of the waveform of the maximum wave centered at the peak angle θ1. The peak angle θ1 is the circumferential angle of the rotor 30 corresponding to the maximum absolute value of the peak voltage.

[0074] The estimation accuracy determination unit 66 calculates the center angle θ2 of the maximum wave. The center angle θ2 is the circumferential angle corresponding to the center of the half-width of the maximum wave.

[0075] according to Figure 6 The center angle θ2 is 44°. The center angle θ2 is closer to the third slot than the second slot. The angle difference Δθ between the peak angle θ1 and the center angle θ2 is 6°, which is greater than half of the 7.42° that is the rotor slot spacing.

[0076] For example, if the maximum wave is symmetrical about left and right with respect to the peak angle θ1, then the peak angle θ1 and the center angle θ2 are the same. For example, if the maximum wave is deformed to the left and right and becomes asymmetrical about left and right with respect to the peak angle θ1, or if the amplitude of the maximum wave varies significantly locally on either side, then the peak angle θ1 and the center angle θ2 are not the same.

[0077] As mentioned above, a short circuit in the excitation winding 32 can be detected by the presence of a wide peak waveform. However, under conditions of maximum waveform deformation, it is difficult to accurately determine which rotor slot 33 the short circuit occurred in.

[0078] Therefore, the estimation accuracy determination unit 66 determines the estimation accuracy based on the angle difference Δθ. As a result, the accuracy of the estimation of the short-circuit position of the excitation winding 32 can be quantitatively determined, and the erroneous estimation of the short-circuit position of the excitation winding 32 can be suppressed.

[0079] For example, if the angle difference Δθ is sufficiently small compared to the rotor slot spacing, it can be accurately estimated that a short circuit has occurred in the rotor slot 33 corresponding to the peak angle θ1 and the center angle θ2. On the other hand, for example, if the angle difference Δθ is greater than half of the rotor slot spacing, the rotor slot 33 corresponding to the peak angle θ1 and the rotor slot 33 corresponding to the center angle θ2 cannot be considered to be identical.

[0080] Figure 7 It means in relation to obtaining Figure 6 The diagram shows an example of the difference waveform obtained under different operating conditions of the turbine generator. Under these operating conditions, both the peak angle θ1 and the center angle θ2 are consistent with the circumferential angle of the second slot. Therefore, the angle difference Δθ is zero.

[0081] As from Figure 6 and Figure 7 Understand that, Figure 7 The symmetry of the largest wave in the middle is higher than that of the others. Figure 6 The degree of symmetry of the maximum wave's waveform. As mentioned above, the closer the angle difference Δθ is to zero, the higher the degree of symmetry of the maximum wave's waveform, and the higher the estimation accuracy.

[0082] Figure 8 It means that the assumption will Figure 2 The voltage signal shown is directly input to Figure 1 A graph of the difference waveform obtained under the condition of short-circuit detection unit 65. According to... Figure 8 In addition to the wave corresponding to the second slot, there are multiple local waves. Therefore, in this case, it is possible to mistakenly assume that the excitation winding 32 is also short-circuited in rotor slots 33 other than the second slot.

[0083] However, according to the short-circuit detection device 60 of Embodiment 1, since even-numbered frequency components above the threshold are removed, it is possible to obtain... Figure 6 and Figure 7 The waveform shows a difference. Therefore, it is difficult to mistakenly conclude that a short circuit occurred in the excitation winding 32 outside the second slot.

[0084] Figure 9 Yes Figure 1 The flowchart shows the short-circuit detection routines executed by each functional module of the short-circuit detection device 60. Figure 9 The routine, for example, is started by activating the short-circuit detection device 60 and is executed at regular intervals.

[0085] When it begins Figure 9 In the routine, the signal acquisition unit 61 first acquires a voltage signal from the detection coil 50 in step S105. Then, the signal decomposition unit 62 performs frequency analysis on the amplitude and phase of the acquired voltage signal in step S110.

[0086] Next, the specific frequency component reduction unit 63 reduces the frequency components of the amplitude after frequency analysis in step S115. That is, the specific frequency component reduction unit 63 removes even-numbered frequency components greater than a threshold from the amplitude and attenuates all odd-numbered frequency components to 1 / 50.

[0087] Next, in step S120, the signal conversion unit 64 converts the phase and the amplitude processed by the specific frequency component reduction unit 63 into a voltage signal.

[0088] Next, in step S125, the short-circuit detection unit 65 divides the converted voltage signal into 180° intervals corresponding to the electrical angles of each magnetic pole, and compares the voltage signals of adjacent 180° electrical angles with each other. In other words, it generates a difference waveform of adjacent 180° electrical angles.

[0089] Next, in step S130, the short-circuit detection unit 65 determines whether there is a peak waveform in the generated difference waveform whose width is greater than the rotor slot spacing. If there is no wide peak waveform, in step S150, the short-circuit detection unit 65 outputs information indicating "no short circuit has occurred" to the display device 70, temporarily ending the routine.

[0090] On the other hand, when a wide peak waveform exists in the difference waveform, the short-circuit detection unit 65 calculates the peak angle θ1 and center angle θ2 of the wide peak waveform in step S135. Furthermore, the short-circuit detection unit 65 estimates the short-circuit location of the excitation winding 32 based on the calculated peak angle θ1 in step S135. The short-circuit location is indicated, for example, by the name of the rotor slot 33 where the short circuit occurred, such as "second slot".

[0091] Next, in step S140, the estimation accuracy determination unit 66 determines the estimation accuracy of the short circuit location based on the calculated peak angle θ1 and center angle θ2.

[0092] Next, in step S145, the estimation accuracy determination unit 66 outputs information such as "short circuit has occurred", "short circuit location" and "estimated accuracy of short circuit location" to the display device 70, temporarily ending the routine.

[0093] Thus, the short-circuit detection method of Implementation Method 1 includes a signal acquisition step, a signal decomposition step, a specific frequency component reduction step, a signal conversion step, a short-circuit detection step, and an estimated accuracy determination step.

[0094] The signal acquisition step is the step of acquiring a voltage signal from a detection coil 50 opposite to the excitation winding 32. The signal decomposition step is the step of decomposing the voltage signal acquired by the signal acquisition step into multiple frequency components with different frequencies.

[0095] The specific frequency component reduction step involves using frequencies lower than the fundamental order of the higher harmonics of the slot as a threshold to attenuate odd-order frequency components and remove even-order frequency components higher than the threshold. The signal conversion step converts the multiple frequency components processed by the specific frequency component reduction step into a voltage signal.

[0096] The short-circuit detection step includes the following steps: dividing the voltage signal converted by the signal conversion step according to the circumferential angle of the rotor 30 corresponding to the multiple magnetic poles of the rotor 30, and generating a difference waveform of each voltage signal corresponding to an adjacent magnetic pole among the multiple magnetic poles. Furthermore, the short-circuit detection step includes detecting a short circuit in the excitation winding based on the shape of the difference waveform, and estimating the location of the short circuit in the excitation winding in the circumferential direction of the rotor 30.

[0097] The estimation accuracy determination step is a step that determines the estimation accuracy of the location of the short circuit based on the symmetry of the waveform of the maximum wave centered at the peak angle θ1.

[0098] Furthermore, the short-circuit detection program in Implementation 1 is a program used to cause a computer to execute the short-circuit detection method described above.

[0099] In other words, a short-circuit detection program is a program that enables a computer to perform signal acquisition and processing, signal decomposition and processing, specific frequency component reduction and processing, signal conversion and processing, short-circuit detection and processing, and estimation accuracy determination and processing.

[0100] The signal acquisition processing includes acquiring a voltage signal from a detection coil 50 opposite to the excitation winding 32. The signal decomposition processing includes decomposing the voltage signal acquired by the signal acquisition processing into multiple frequency components of different orders.

[0101] The specific frequency component reduction processing includes the following steps: using frequencies lower than the fundamental order of the higher harmonics of the slot as a threshold, attenuating the odd-order frequency components among multiple frequency components, and removing the even-order frequency components higher than the threshold. Signal conversion processing includes converting the multiple frequency components processed by the specific frequency component reduction processing into a voltage signal.

[0102] The short-circuit detection process includes the following steps: dividing the voltage signal, after being converted through a signal conversion step, according to the circumferential angles of the rotor 30 corresponding to the multiple magnetic poles of the rotor 30, and generating difference waveforms for each voltage signal corresponding to adjacent magnetic poles among the multiple magnetic poles. Furthermore, the short-circuit detection process includes detecting a short circuit in the excitation winding based on the shape of the difference waveform, and estimating the location of the short circuit in the excitation winding within the circumference of the rotor 30.

[0103] The estimation accuracy determination process includes determining the estimation accuracy of the short circuit location based on the symmetry of the waveform of the maximum wave centered at the peak angle θ1.

[0104] As described above, according to the short-circuit detection device 60 and short-circuit detection method of Embodiment 1, it is possible to estimate the location of the short circuit in the excitation winding 32 in the circumferential direction of the rotor 30. Moreover, it is possible to determine the accuracy of the estimation of the short-circuit location of the excitation winding 32.

[0105] Furthermore, the estimation accuracy determination unit 66 calculates the circumferential angle θ2 as the center angle of the center of the half-width of the maximum wave. This makes it easier to calculate the symmetry of the maximum wave's waveform.

[0106] Furthermore, the specific frequency component reduction unit 63 estimates the fundamental order of the higher harmonics of the slot based on the amplitude of each frequency component. This saves the user time and effort in frequency analysis by specifying thresholds and the order of frequency components to be removed.

[0107] Furthermore, the estimation accuracy determination unit 66 outputs information related to whether a short circuit has occurred in the excitation winding 32, the location of the short-circuited rotor slot 33, and the estimation accuracy of the location of the short-circuited rotor slot 33 to the display device 70. Thus, the user can know whether a short circuit has occurred in the excitation winding 32, the location of the short-circuited rotor slot 33, and the estimation accuracy of the location of the short-circuited rotor slot 33.

[0108] Furthermore, the short-circuit detection unit 65 detects a short circuit in the excitation winding 32 based on the peak waveform appearing in the difference waveform, and estimates that a short circuit in the excitation winding 32 has occurred in the rotor slot 33 corresponding to the peak angle θ1. This makes it easier to estimate the location of the short circuit in the excitation winding 32.

[0109] Implementation Method 2

[0110] Next, the short-circuit detection device of Embodiment 2 will be described. In Embodiment 1, the specific frequency component reduction unit 63 attenuates the amplitude of all odd-order frequency components to 1 / 50. In contrast, in Embodiment 2, the specific frequency component reduction unit 63 makes the amplitude of odd-order frequency components below a threshold zero. Therefore, only even-order frequency components are included among the frequency components below the threshold. In this embodiment, reducing frequency components includes making the amplitude of the frequency components zero.

[0111] The other structures in Implementation 2 are the same as those in Implementation 1.

[0112] If even-order frequency components are considered to be signal components used to detect short circuits in the excitation winding 32, then odd-order frequency components are considered to be noise components. Therefore, by making the amplitude of odd-order frequency components below the threshold zero, the signal-to-noise ratio (SN ratio) of the difference waveform can be improved, thereby increasing the detection accuracy of whether a short circuit has occurred.

[0113] However, in this case, since the odd-numbered frequency components below the threshold are not included, it is impossible to accurately determine the circumferential angles of the first magnetic pole 36 and the second magnetic pole 37. However, sometimes the short-circuit location of the excitation winding 32 can be estimated based on the angle difference between the circumferential angle of the positive peak voltage and the circumferential angle of the negative peak voltage.

[0114] Thus, in the short-circuit detection device 60 of Embodiment 2, the specific frequency component reduction section 63 makes the amplitude of the odd-numbered frequency components below the threshold zero. As a result, a short circuit in the excitation winding 32 can be detected with higher accuracy.

[0115] Furthermore, in embodiments 1 and 2, the fundamental order of the slot higher harmonics is estimated by the specific frequency component reduction unit 63. However, the fundamental order of the slot higher harmonics is determined by the number of magnetic poles, the arrangement of the rotor slots 33, etc. Therefore, the fundamental order and threshold of the slot higher harmonics can also be stored in advance by the specific frequency component reduction unit 63.

[0116] Furthermore, in embodiments 1 and 2, the voltage can be determined as long as it is lower than the maximum value of the voltage of the maximum wave, and it does not have to be a half-value voltage.

[0117] In addition, in embodiments 1 and 2, the estimation accuracy determination unit 66 determines the estimation accuracy based on the angle difference Δθ between the peak angle θ1 and the center angle θ2. However, the method for determining the estimation accuracy is not particularly limited as long as it is based on the symmetry of the waveform of the maximum wave.

[0118] Figure 10 It means based on Figure 1 A diagram showing other determination methods for the estimation accuracy determination unit 66. For example... Figure 10 As shown, for example, the estimation accuracy determination unit 66 can also determine the estimation accuracy based on the difference between the first angle difference Δθ1 and the second angle difference Δθ2. The first angle difference Δθ1 is the angle difference between the circumferential angle θ3 corresponding to the determination voltage and the peak angle θ1 on the side of the maximum value. The second angle difference Δθ2 is the angle difference between the circumferential angle θ4 corresponding to the determination voltage and the peak angle θ1 on the other side of the maximum value.

[0119] In this case, the smaller the difference between the first angle difference Δθ1 and the second angle difference Δθ2, the higher the estimation accuracy.

[0120] exist Figure 10 In this context, the judgment voltage is set to the half-value voltage, but the judgment voltage is not limited to the half-value voltage.

[0121] Alternatively, for example, the estimation accuracy can be determined based on the difference between the magnitude of the positive slope and the magnitude of the negative slope of the maximum wave in the determination voltage. The determination voltage can be the half-value voltage or any voltage smaller than the maximum value. In this case, it is also determined that the smaller the difference, the higher the estimation accuracy.

[0122] Alternatively, in embodiments 1 and 2, a threshold for estimating accuracy can be set. If the estimating accuracy based on the estimating accuracy determination unit 66 is lower than the threshold, the operating conditions of the turbine generator 10 are changed, and the process is repeated. Figure 9 The short-circuit detection routine is provided. Therefore, the short-circuit location of the excitation winding 32 is estimated with higher estimation accuracy.

[0123] Furthermore, in embodiments 1 and 2, the number of stator slots 23, the number of rotor slots, the number of magnetic poles, and the rotor slot spacing are not limited to the examples described above.

[0124] For example, when there are more than two magnetic poles, the short-circuit detection unit 65 only needs to generate a difference waveform as follows: The short-circuit detection unit 65 first divides the voltage signal converted by the signal conversion unit 64 into segments corresponding to each circumferential angle of the rotor and each of the multiple magnetic poles. Furthermore, the short-circuit detection unit 65 only needs to generate a difference waveform of each voltage signal corresponding to an adjacent magnetic pole among the multiple magnetic poles.

[0125] Furthermore, in embodiments 1 and 2, there is only one type of rotor slot spacing, but multiple rotor slot spacings can also exist. When multiple rotor slot spacings exist, a threshold can be set by considering the voltage component with the largest value among the multiple slot slot harmonics—that is, the lowest order of the slot harmonics—as the fundamental order of the slot harmonics. Therefore, frequency components corresponding to all rotor slot spacings can be removed.

[0126] Furthermore, in embodiments 1 and 2, the specific frequency component reduction unit 63 may not necessarily reduce all odd-order frequency components. That is, the specific frequency component reduction unit 63 may retain a portion of the odd-order frequency components without reducing them, within the range where even-order frequency components can be detected.

[0127] Furthermore, in embodiments 1 and 2, the specific frequency component reduction unit 63 may not necessarily remove even-order frequency components higher than the threshold. That is, the specific frequency component reduction unit 63 may attenuate even-order frequency components higher than the threshold within the range where the peak waveform with a width greater than the rotor slot spacing is obtained in the difference waveform of the short-circuit detection unit 65.

[0128] Furthermore, in embodiments 1 and 2, the signal decomposition unit 62 decomposes the voltage signal into multiple frequency components with different frequencies, and then separates the multiple frequency components into amplitude and phase. Then, the specific frequency component reduction unit 63 performs processing to reduce the amplitude of specific frequency components. However, the method of decomposing the signal is not particularly limited to this.

[0129] For example, the signal decomposition unit 62 can decompose the voltage signal into multiple frequency components with different frequencies, and the specific frequency component reduction unit 63 can reduce specific frequency components from the multiple decomposed frequency components. This simplifies the signal decomposition process.

[0130] In addition, in embodiments 1 and 2, the rotor 30 is disposed on the inner circumferential side of the stator 20, but the rotor 30 may also be disposed on the outer circumferential side of the stator 20.

[0131] In addition, in embodiments 1 and 2, a turbine generator 10 is used as a rotating motor, but the rotating motor may also be a generator other than the turbine generator 10, or it may be an electric motor.

[0132] In addition, the function of the short-circuit detection device 60 in embodiments 1 and 2 is implemented by the processing circuit. Figure 11 This is a structural diagram of a first example of a processing circuit that implements the functions of the short-circuit detection device 60 in embodiments 1 and 2. The processing circuit 100 in the first example is dedicated hardware.

[0133] In addition, the processing circuit 100 may be equivalent to a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0134] Figure 12 This is a structural diagram of a second example of a processing circuit that implements the functions of the short-circuit detection device 60 in embodiments 1 and 2. The processing circuit 200 of the second example includes a processor 201 and a memory 202.

[0135] In the processing circuit 200, the function of the short-circuit detection device 60 is implemented through software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the memory 202. The processor 201 implements the various functions by reading and executing the programs stored in the memory 202.

[0136] The program stored in memory 202 can also be described as a program that causes the computer to execute the steps or methods described above. Here, memory 202 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read-Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable and Programmable Read Only Memory). Furthermore, disks, floppy disks, optical disks, compact disks, microdisks, DVDs, etc., also correspond to memory 202.

[0137] In addition, the functions of the short-circuit detection device 60 mentioned above can be implemented partly with dedicated hardware and partly with software or firmware.

[0138] Thus, the processing circuit can realize the functions of the short-circuit detection device 60 described above through hardware, software, firmware, or a combination thereof.

[0139] Explanation of reference numerals in the attached figures

[0140] 10 Turbine generator (rotating motor), 20 Stator (armature), 21 Stator core, 22 Multiphase winding, 23 Stator slot, 30 Rotor (excitation component), 31 Rotor core, 32 Excitation winding, 33 Rotor slot, 36 First magnetic pole, 37 Second magnetic pole, 40 Gap, 50 Detection coil (magnetic detector), 60 Short circuit detection device, 61 Signal acquisition unit, 62 Signal decomposition unit, 63 Specific frequency component reduction unit, 64 Signal conversion unit, 65 Short circuit detection unit, 66 Estimated accuracy determination unit.

Claims

1. A short-circuit detection device for a rotating electric machine, wherein, The short-circuit detection device for this rotary electric motor includes: The signal acquisition unit acquires a voltage signal from a magnetic detector, which faces the excitation windings of multiple slots provided in the excitation element; The signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into multiple frequency components with different frequencies. The specific frequency component reduction section uses a threshold number that is lower than the fundamental number of the higher harmonics related to the spacing of the plurality of slots, i.e., the slot higher harmonics, as a threshold number, and reduces the odd-order frequency components and the even-order frequency components that are higher than the threshold number among the plurality of frequency components. The fundamental number of the slot higher harmonics is the number of the slot higher harmonic with the lowest number among the plurality of slot higher harmonics. The signal conversion unit converts multiple frequency components output from the specific frequency component reduction unit into voltage signals; The short-circuit detection unit divides the voltage signal converted by the signal conversion unit according to the circumferential angle of the excitation element corresponding to the multiple magnetic poles of the excitation element, and generates a difference waveform of each voltage signal corresponding to an adjacent magnetic pole among the multiple magnetic poles. Based on the shape of the difference waveform, the unit detects the short circuit of the excitation winding and estimates at which position of the short circuit of the excitation winding occurs in the circumferential direction of the excitation element. as well as The estimation accuracy determination unit determines the estimation accuracy of the location where the short circuit occurred. In the difference waveform, when the wave containing the maximum absolute value of the peak voltage is designated as the maximum wave, and the circumferential angle of the excitation element corresponding to the maximum value is designated as the peak angle, The estimation accuracy determination unit determines the estimation accuracy of the location where the short circuit occurred based on the degree of symmetry of the waveform of the maximum wave centered on the peak angle.

2. The short-circuit detection device for a rotating electric motor according to claim 1, wherein, The estimation accuracy determination unit determines the estimation accuracy based on the angle difference between the peak angle and the center angle. The center angle is the circumferential angle of the center of the width of the maximum wave in the determination voltage, which is smaller than the maximum value of the maximum wave.

3. The short-circuit detection device for a rotating electric motor according to claim 2, wherein, The determination voltage is a voltage that is half of the maximum value.

4. The short-circuit detection device for a rotating electric machine according to any one of claims 1 to 3, wherein, The specific frequency component reduction section estimates the fundamental order of the higher harmonics of the slot based on the amplitude of each frequency component.

5. The short-circuit detection device for a rotating electric machine according to any one of claims 1 to 3, wherein, The specific frequency component reduction section makes the amplitude of the odd-numbered frequency components below the threshold zero.

6. The short-circuit detection device for a rotating electric machine according to any one of claims 1 to 3, wherein, The estimation accuracy determination unit outputs information to the outside related to whether the excitation winding has short-circuited, the position of the slot where the short circuit has occurred, and the estimation accuracy of the position of the slot where the short circuit has occurred.

7. The short-circuit detection device for a rotating electric machine according to any one of claims 1 to 3, wherein, The short-circuit detection unit detects a short circuit in the excitation winding based on the peak waveform that appears in the difference waveform, and presumes that a short circuit in the excitation winding has occurred in the slot corresponding to the peak angle.

8. A short-circuit detection method for a rotating electric machine, wherein, The short-circuit detection method for this rotating electric motor includes: In the signal acquisition step, a voltage signal is acquired from a magnetic detector, which is opposite to the excitation windings of multiple slots disposed in the excitation element; The signal decomposition step decomposes the voltage signal obtained through the signal acquisition step into multiple frequency components with different frequencies. The specific frequency component reduction step uses a threshold number that is lower than the fundamental number of the higher harmonics related to the spacing of the plurality of slots, i.e., the slot higher harmonics, and reduces the odd-order frequency components and the even-order frequency components that are higher than the threshold number among the plurality of frequency components. The fundamental number of the slot higher harmonics is the number of the slot higher harmonic with the lowest number among the plurality of slot higher harmonics. The signal conversion step converts the multiple frequency components processed by the specific frequency component reduction step into a voltage signal; The short-circuit detection step divides the voltage signal converted by the signal conversion step according to the circumferential angle of the excitation element corresponding to the multiple magnetic poles of the excitation element, and generates a difference waveform of each voltage signal corresponding to the adjacent magnetic poles among the multiple magnetic poles. Based on the shape of the difference waveform, the short circuit of the excitation winding is detected, and the position of the short circuit of the excitation winding in the circumferential direction of the excitation element is estimated. as well as The estimation accuracy determination step determines the estimation accuracy of the location where the short circuit occurred. In the difference waveform, when the wave containing the maximum absolute value of the peak voltage is designated as the maximum wave, and the circumferential angle of the excitation element corresponding to the maximum value is designated as the peak angle, The estimation accuracy determination step determines the estimation accuracy of the location where the short circuit occurred based on the degree of symmetry of the waveform of the maximum wave centered on the peak angle.

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