Short circuit detection device and short circuit detection method for rotating electrical machine

Abstract

A short-circuit detection device (100) for a rotating electrical machine (10) is provided with a signal acquisition unit (61), a signal decomposition unit (62), and a short-circuit detection unit (63), and detects a short circuit of a stator core (21). The signal decomposition unit (62) decomposes the voltage signal from the signal acquisition unit (61) into a plurality of frequency components having different numbers of times. A short circuit detection unit (63) determines a short circuit of the stator core (21) by comparing an amplitude change of an odd-numbered low-order harmonic component with an amplitude change of a primary frequency component on the basis of output results of the signal decomposition unit (62) on the basis of two unit voltage signals acquired at different time points.

Description

Technical Field

[0001] The present application relates to a short - circuit detection device and a short - circuit detection method for a rotating electric machine. Background Art

[0002] In the stator core of a rotating electric machine using a laminated core, short - circuits sometimes occur between laminations via axial fasteners. If a large short - circuit current flows between the laminations of the stator core, in addition to an increase in heat loss, faults such as an increase in the vibration of the rotating electric machine or an imbalance in the three - phase currents output by the rotating electric machine may occur. In particular, when the rotating electric machine operates under a high - load condition, the magnetic flux density inside the rotating electric machine is in a relatively high state. If a short - circuit occurs between the laminations of the stator core, a large change occurs in the balance between the respective frequency components of the magnetic flux density.

[0003] In the prior art described in Patent Document 1, in a rotating electric machine in which a rotor holding an exciting winding and a stator are separated by a gap, a device for monitoring the magnetic field flux in the gap and a device for detecting the even - order harmonics of the magnetic flux wave are provided. Moreover, faults of the rotating electric machine are detected by detecting the even - order harmonics of the voltage induced in a detection coil disposed in the gap. In addition, in the prior art described in Patent Document 2, it is described that when the magnetic flux generated in the rotating electric machine is affected by magnetic saturation, odd - order harmonic currents flow through the stator winding, and harmonic magnetic fluxes are generated inside the rotating electric machine under the influence of the magnetic field generated by the current. Moreover, it is described that by improving the stator core structure, the generation of harmonic currents due to magnetic saturation is suppressed, thereby reducing the vibration and electromagnetic noise of the rotating electric machine. Prior Art Documents Patent Documents

[0004] Patent Document 1: Japanese Patent Laid - Open No. 53 - 84101 Patent Document 2: Japanese Patent Laid - Open No. 2010 - 130839 Summary of the Invention Technical Problem to be Solved by the Invention

[0005] In the prior art described in Patent Document 1 above, the short - circuit of the exciting winding of the rotor can be detected by detecting the even - order harmonics of the voltage induced in the detection coil, but the short - circuit between the laminations of the stator core cannot be detected. In addition, although the prior art described in Patent Document 2 above reduces the adverse effects of magnetic saturation, the detection of short - circuits between the laminations of the stator core is not considered. Therefore, there is a problem that when a rotating electric machine operates in a state where the magnetic flux density of the stator core is relatively high, even if a short - circuit occurs between the laminations of the stator core, the occurrence of the short - circuit cannot be detected with high precision.

[0006] The present application discloses a technology for solving the above problems, and its object is to provide a short-circuit detection device and a short-circuit detection method for a rotating electric machine, which can accurately detect a short circuit occurring between laminations of a stator core when the rotating electric machine is operating in a state where the magnetic flux density of the stator core is relatively high. Technical means for solving technical problems

[0007] The short-circuit detection device for a rotating electric machine disclosed in the present application includes: a signal acquisition unit that acquires a voltage signal from a magnetic detector disposed opposite to the rotor of the rotating electric machine on the stator side; a signal decomposition unit that decomposes the voltage signal into a plurality of frequency components with different orders; and a short-circuit detection unit that determines a short circuit of the stator core formed by laminations based on odd-order low-order harmonic components and fundamental frequency components among the frequency components decomposed by the signal decomposition unit. The signal acquisition unit acquires the voltage signal in units of one electrical angular cycle. The short-circuit detection unit detects changes in the amplitudes of the low-order harmonic components and the fundamental frequency components respectively based on two units of the voltage signals acquired at different time points, and determines the short circuit of the stator core based on a comparison between the changes in the amplitudes of the low-order harmonic components and the fundamental frequency components.

[0008] In addition, the short-circuit detection method for a rotating electric machine disclosed in the present application includes: a signal acquisition step of acquiring a voltage signal from a magnetic detector disposed opposite to the rotor of the rotating electric machine on the stator side; a signal decomposition step of decomposing the voltage signal into a plurality of frequency components with different orders; and a short-circuit detection step of determining a short circuit of the stator core formed by laminations based on odd-order low-order harmonic components and fundamental frequency components among the frequency components decomposed in the signal decomposition step. In the signal acquisition step, the voltage signal is acquired in units of one electrical angular cycle. In the short-circuit detection step, changes in the amplitudes of the low-order harmonic components and the fundamental frequency components are detected respectively based on two units of the voltage signals acquired at different time points, and the short circuit of the stator core is determined based on a comparison between the changes in the amplitudes of the low-order harmonic components and the fundamental frequency components. Advantages of the invention

[0009] According to the short-circuit detection device and the short-circuit detection method for a rotating electric machine disclosed in the present application, a short circuit occurring between laminations of a stator core can be accurately detected when the rotating electric machine is operating in a state where the magnetic flux density of the stator core is relatively high. Description of the drawings

[0010] Figure 1 This is a structural diagram showing the rotating electrical machine and short - circuit detection device of Embodiment 1. Figure 2 This is a waveform diagram showing the voltage signal in a healthy state acquired by the signal acquisition unit of Embodiment 1. Figure 3 This is a waveform diagram showing the voltage signal during a short - circuit acquired by the signal acquisition unit of Embodiment 1. Figure 4 This is a diagram showing the magnetic flux density distribution when the stator core of Embodiment 1 is short - circuited. Figure 5 This is a spectrogram showing the amplitudes of the odd - numbered components in the frequency components decomposed by the signal decomposition unit of Embodiment 1 in a healthy state and during a short - circuit. Figure 6 This is a diagram showing the amplitude ratio of each frequency component calculated by the short - circuit detection unit of Embodiment 1. Figure 7 This is a diagram showing the flow for explaining the short - circuit detection method of Embodiment 1. Figure 8 This is a structural diagram showing an example of the hardware for implementing each function of the signal processing device of Embodiment 1. Figure 9 This is a structural diagram showing another example of the hardware for implementing each function of the signal processing device of Embodiment 1. Figure 10 This is a diagram showing the amount of change in the amplitude of each frequency component calculated by the short - circuit detection unit of Embodiment 2. Figure 11 This is a diagram showing the differential signal of two different voltage signals acquired by the signal acquisition unit of Embodiment 3. Figure 12 This is a spectrogram showing the amplitude ratio of each frequency component calculated by the short - circuit detection unit of Embodiment 3. Detailed Embodiments

[0011] Embodiment 1. Hereinafter, the embodiments will be described with reference to the drawings. Figure 1 This is a structural diagram showing the rotating electrical machine and short - circuit detection device of Embodiment 1. In Embodiment 1, a turbo - generator 10 is used as the rotating electrical machine. Figure 1 In the figure, a cross - section perpendicular to the axial direction of the turbo - generator 10 is shown.

[0012] As Figure 1 shown, the turbo - generator 10 includes a stator 20 as an armature and a rotor 30 as an exciter. The stator 20 is disposed outside the rotor 30. The stator 20 has a cylindrical stator core 21 and a polyphase winding 22 (not shown in the figure), and a plurality of stator slots 23 are formed in the inner peripheral portion of the stator core 21.

[0013] The axial direction of the stator core 21 is the direction along the axis of the stator core 21 and is perpendicular to Figure 1 the plane of the paper. The radial direction of the stator core 21 is the radial direction of a circle centered on the axis of the stator core 21. The circumferential direction of the stator core 21 is the direction along an arc centered on the axis of the stator core 21. Each of the stator slots 23 formed in the inner peripheral portion of the stator core 21 is provided 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. The polyphase winding 22 is wound around the plurality of stator slots 23.

[0014] The stator core 21 has a laminated structure formed by laminating steel plates, and fasteners 81 and 82 are provided inside and outside the stator core 21. The fasteners 81 and 82 pass through the stator core 21 respectively and hold the laminated stator core 21.

[0015] The rotor 30 includes a rotor core 31, an exciting winding 32 (not shown in the figure), and a rotating shaft (not shown). The rotor core 31 and the rotating shaft are arranged coaxially with the stator core 21. The rotor 30 can rotate about the rotating shaft. A plurality of rotor slots 33 are formed in the outer peripheral portion of the rotor core 31. Each of the rotor slots 33 is formed along the radial direction of the rotor core 31. In this case, the plurality of rotor slots 33 are divided into two slot groups, and a first magnetic pole 34 and a second magnetic pole 35 are formed between the two slot groups. In each slot group, the plurality of rotor slots 33 are arranged at equal intervals in the circumferential direction of the rotor core 31.

[0016] The exciting winding 32 is excited by a DC power supply (not shown). As a result, one of the first magnetic pole 34 and the second magnetic pole 35 becomes an N pole and the other becomes an S pole. That is, the turbo generator 10 is a two-pole generator.

[0017] An air gap 40 is formed between the stator core 21 and the rotor core 31. The polyphase winding 22 is excited by an AC power supply (not shown). As a result, a rotating magnetic field is generated in the air gap 40.

[0018] The short-circuit detection device 100 detects a short circuit between the laminations of the stator core 21 of the turbo generator 10, and includes a detection coil 50 as a magnetic detector, a signal processing device 60 for processing the detection signal from the detection coil 50, and a display device 70. The detection coil 50 is arranged in the air gap 40 opposite to the rotor 30. In addition, the detection coil 50 can be disposed inside the stator core 21 including the stator slots 23 close to the air gap 40, relative to the rotor 30. That is, the detection coil 50 is disposed on the stator 20 side including the air gap 40, relative to the rotor 30.

[0019] The main magnetic flux and the leakage magnetic flux are linked to the detection coil 50. The main magnetic flux is the magnetic flux generated in the air gap 40, and the leakage magnetic flux is the magnetic flux leaking from each rotor slot 33. The magnetic flux linked to the detection coil 50 is referred to as the linked magnetic flux.

[0020] The detection coil 50 includes a first terminal 51 and a second terminal 52. When the magnetic flux is linked to the detection coil 50, a voltage signal as a detection signal is induced between the first terminal 51 and the second terminal 52. The distribution of the linked magnetic flux in the detection coil 50 changes as the rotor 30 rotates. In addition, in this case, the short-circuit detection device 100 includes the detection coil 50 as a magnetic detector, but the detection coil 50 can be configured separately from the short-circuit detection device 100.

[0021] The signal processing device 60 includes a signal acquisition unit 61, a signal decomposition unit 62, and a short-circuit detection unit 63 as functional blocks. The signal acquisition unit 61 acquires the voltage signal induced by the detection coil 50. The signal decomposition unit 62 decomposes the acquired voltage signal into a plurality of frequency components having different orders from each other. The voltage signal acquired by the signal acquisition unit 61 is processed in units of one electrical angular cycle. The signal decomposition unit 62 decomposes the voltage signal of one electrical angular cycle into each frequency component. In addition, the signal decomposition unit 62 separates each decomposed frequency component into an amplitude and a phase.

[0022] The short-circuit detection unit 63 analyzes the amplitudes of the odd-order frequency components among the decomposed frequency components. The odd-order frequency components include: a fundamental wave component, which is a first-order component that vibrates once within one electrical angular cycle corresponding to the two poles of the first magnetic pole 34 and the second magnetic pole 35; and a harmonic component, which is a harmonic component of the third order or higher other than the first-order component. The short-circuit detection unit 63 determines the short circuit of the laminated stator core 21 based on the odd-order low-order harmonic components and the first-order component.

[0023] When the operating state of the turbo generator 10 does not change and the stator core 21 does not short-circuit, the amplitudes of the odd-order frequency components decomposed by the signal decomposition unit 62 remain unchanged. In addition, even when the operating state of the turbo generator 10 remains unchanged, the stator core 21 short-circuits, and this short-circuit state is constant, the amplitudes of the odd-order frequency components decomposed by the signal decomposition unit 62 also remain unchanged.

[0024] On the other hand, even if the operating state of the turbogenerator 10 does not change, the amplitudes of the odd-numbered frequency components decomposed by the signal decomposition unit 62 are different between the voltage signals of one electrical angular cycle obtained before the short circuit occurs in the stator core 21 and the voltage signals of one electrical angular cycle obtained after the short circuit occurs. That is, when the amplitudes of the odd-numbered frequency components obtained by frequency decomposing two unit voltage signals obtained successively at different time points in units of one (one electrical angular cycle) change between the two unit voltage signals, a short circuit in the stator core 21 can be detected.

[0025] Among the two unit voltage signals, the signal acquisition unit 61 successively acquires the voltage waveforms of one unit voltage signal continuously or intermittently at time intervals. When a change in the amplitude of each odd-numbered frequency component is observed between the past voltage signal obtained before the short circuit occurs and the newly acquired voltage signal, a new short circuit occurrence in the stator core 21 can be detected.

[0026] The short circuit detection unit 63 calculates the amplitude ratio as the change in the amplitude of each odd-numbered frequency component of two unit voltage signals in the same operating state of the turbogenerator 10. In the present embodiment, when the amplitude ratio of the third harmonic component is greater than the amplitude ratio of the fundamental component, the short circuit detection unit 63 detects that a short circuit has occurred in the stator core 21.

[0027] In addition, the short circuit detection unit 63 outputs information on whether there is a short circuit in the stator core 21 to the display device 70.

[0028] The display device 70 is provided outside the signal processing device 60. The display device 70 displays whether there is a short circuit in the stator core 21 based on the information from the short circuit detection unit 63. In addition, the display device 70 may be provided outside the short circuit detection device 100.

[0029] Figure 2 is a waveform diagram showing the voltage signal in a sound state acquired by the signal acquisition unit 61. In addition, Figure 3 is a waveform diagram showing the voltage signal in a short-circuited state acquired by the signal acquisition unit 61. Figure 2 and Figure 3 show examples of voltage signals in a sound state and a short-circuited state. The horizontal axis corresponds to one electrical angular cycle corresponding to the two poles of the first magnetic pole 34 and the second magnetic pole 35. In addition, Figure 4 is a diagram showing the magnetic flux density distribution when the stator core 21 is short-circuited, and shows the magnetic flux density distribution at the time point when the Figure 3 voltage signal is acquired.

[0030] Figures 2 to 4 It is obtained by simulating the no-load operation state of the turbine generator 10 generating the rated voltage using an electromagnetic field analysis program. The simulation of the short circuit is performed under the condition that the stator core 21 is short-circuited via the fastener 83, which passes through the stator core 21 and is held inside or on the outer periphery of the stator core 21. Figure 1 The fastener 81A at the same circumferential position as the detection coil 50 shown and inside the stator core 21, and the fastener 82A arranged at the outer periphery of the stator core 21 and at circumferential positions on both sides of the fastener 81A become fasteners 83 that constitute a short circuit.

[0031] When detecting a short circuit in the stator core 21, it is important to quickly detect a situation where a large short circuit current flows between the laminations of the stator core 21 due to the short circuit. Therefore, in the simulation of the short circuit, the distance between the fasteners 83 constituting the short circuit circuit is short, and the condition is set so that a large short circuit current is likely to flow.

[0032] In this example, the signal processing device 60 estimates the occurrence of a short circuit in the stator core 21 using the voltage signal acquired by the signal acquisition unit 61. This will be described below.

[0033] Figure 2 and Figure 3 Each of the voltage waveforms shown is a voltage waveform of one electrical angle period, and the circumferential angle of 0° to 180° corresponds to the first magnetic pole 34, and the circumferential angle of 180° to 360° corresponds to the second magnetic pole 35. Therefore, at a circumferential angle of 90°, the center of the first magnetic pole 34 is closest to the detection coil 50, and at a circumferential angle of 270°, the center of the second magnetic pole 35 is closest to the detection coil 50.

[0034] Figure 2 The voltage waveform shown is a healthy voltage waveform without short circuit, and 32 fine voltage fluctuations are generated in each rotor slot pitch. Figure 3 The voltage waveform shown in is the voltage waveform when a short circuit occurs. As described later, the amplitude of the harmonic component increases, but from the perspective of the entire waveform, it becomes the same as Figure 2 Basically the same waveform.

[0035] As described above, the signal decomposition unit 62 decomposes the voltage signal acquired by the signal acquisition unit 61 into a plurality of frequency components of different orders, and further separates each of the decomposed frequency components into an amplitude and a phase. Figure 5It is a spectrogram showing the amplitudes of the odd - numbered components among the frequency components decomposed by the signal decomposition unit 62 during normal operation and short - circuit operation. That is, Figure 5 In, for the convenience of absolute - value comparison, based on Figure 2 the amplitude spectrum of the odd - numbered components of the voltage waveform shown in Figure 3 and the amplitude spectrum of the odd - numbered components of the voltage waveform shown in Figure 5 are combined and shown. In addition, although there are components with frequencies above 21, for the sake of explanation, components with frequencies below 19 are shown in

[0036] The fundamental component is the fundamental wave component corresponding to the main magnetic flux in the magnetic flux generated in the air gap 40 and has the largest amplitude. The odd - numbered components above the third order are harmonic components other than the main magnetic flux and are caused by pulsation factors such as the number of slots of the rotor 30 or the stator 20 in the magnetic flux generated in the air gap 40. It can be seen that if a short - circuit occurs, the amplitude of the fundamental component hardly changes, but the amplitudes of the third - order and fifth - order components increase.

[0037] As Figure 4 shown, in the region A surrounded by the fasteners 81A and 82A short - circuited to the stator core 21, due to magnetic shielding, the magnetic - flux density decreases. In contrast, in the region B including the region B1 on the radially inner side of the region A and the region B2 on the opposite side of the region A with respect to the axis, the magnetic - flux density increases due to the shielded and bypassed magnetic flux. Moreover, the magnetic - flux density at the center of the magnetically saturated region becomes high, and the magnetic - flux density of the surrounding part also becomes high, so that the magnetically saturated region becomes larger and the harmonic components increase.

[0038] Since the bypassed magnetic flux bypasses about half a cycle like the region B and forms spatial variations in two or four places together on the back side or tooth side of the core, the magnetic flux mainly shows changes in the magnetic - flux density of the third or fifth order, rather than changes in the magnetic - flux density of the fundamental and higher orders. In addition, the influence of magnetic saturation also appears as harmonic components with frequencies that are multiples of 2 or 4, but the higher the frequency, the smaller the voltage value.

[0039] Basically, the change in magnetic permeability is quadratic, and the change in magnetomotive force is linear. Therefore, the change in magnetic - flux density as their difference is cubic. When the change in magnetic permeability has a fourth - order component as a harmonic component, the change in magnetic - flux density is cubic or fifth - order. Similarly, it also includes harmonics of higher frequencies.

[0040] The short - circuit detection unit 63 calculates the amplitude ratio between the odd - numbered harmonic components decomposed by the signal decomposition unit 62 with the same order as the low - order components. Figure 6 It is a drawing showing the amplitude ratio of each frequency component calculated by the short - circuit detection unit 63 and is based on Figure 5The accompanying drawing for calculating the amplitude ratio of the spectrogram. In addition, in Figure 5 the fifth, eleventh, and seventeenth components with relatively small absolute amplitudes of the amplitude are excluded from the calculation because the SN ratio (signal-noise ratio) of the amplitude ratio is poor.

[0041] For example, if one nth amplitude value is V1n and the other nth amplitude value is V2n, then R = (|V1n - V2n| / V1n) × 100, with the unit of %, is used to calculate the amplitude ratio R. The magnetic saturation region increases with the short circuit. In the state without a short circuit, the amplitude ratio is almost zero, but when a short circuit occurs, the amplitude ratio changes. The fundamental and higher-order frequency components above the seventh order are relatively less affected by magnetic saturation, and the amplitude ratio is also small. In contrast, the third and fifth frequency components, which are low-order harmonic components, exhibit the characteristics of being more affected by magnetic saturation caused by the short circuit, and the amplitude ratio is also large.

[0042] In addition, in this case, it can be known that: the fifth component is excluded, and the amplitude ratio of the third component is large. Generally speaking, the amplitude magnitudes of the third and fifth components depend on the phases of the two components, where one component is large, the other component is small, or both are at a medium level and reach equilibrium.

[0043] As Figure 6 shown, the amplitude ratio of the higher-order frequency components is 0.0% to 1.2%. In contrast, the amplitude ratio of the third component greatly exceeds 1.2% and is approximately 5%. The amplitude ratio of the fundamental component is relatively small, at 0.2%, and the amplitude ratio of the third component is significantly greater than the amplitude ratio of the fundamental component. The short-circuit detection unit 63 detects the occurrence of a short circuit in the stator core 21 based on the comparison between the amplitude ratio of the fundamental component and the amplitude ratio of the third component. For example, when the amplitude ratio of the third component is significantly greater than the amplitude ratio of the fundamental component, it is detected that a short circuit has occurred in the stator core 21. For the determination of a significantly larger amplitude ratio, for example, when the difference or ratio is greater than the set value, it can be determined that the amplitude ratio is significantly larger.

[0044] The determination is made by using the third component, which has the largest absolute value of the amplitude ratio due to the influence of magnetic saturation of the stator core 21, so that the signal-to-noise ratio of the amplitude ratio is good, and the short circuit can be determined more accurately. In addition, in the state where the stator core 21 is magnetically saturated, compared with the non-magnetically saturated state, the amplitude of the harmonic component becomes larger. Therefore, the amplitude ratio of the harmonic component before and after the short circuit in the stator core 21 can be analyzed with a good signal-to-noise ratio. Therefore, the state in which the turbogenerator 10 operates at a higher magnetic flux density is suitable for detecting a short circuit in the stator core 21.

[0045] Next, the short-circuit detection method of this embodiment will be described based on the accompanying drawings. Figure 7 It is a diagram showing the flow of the short-circuit detection method for explaining Embodiment 1. When the short-circuit detection device 100 is started, the signal processing device 60 executes Figure 7 the short-circuit detection process shown in the flowchart at regular intervals.

[0046] When the short-circuit detection process starts, first, the signal acquisition unit 61 acquires a voltage signal for one unit (one electrical angular cycle) from the detection coil 50 (step S110). Next, the signal decomposition unit 62 decomposes the acquired voltage signal into a plurality of frequency components with different orders from each other, and separates them into amplitude and phase (step S120).

[0047] Next, the short-circuit detection unit 63 calculates the amplitude ratio of each odd-order frequency component based on the voltage signals of two units, that is, the voltage signal acquired in the previous process and the voltage signal acquired in the current process, according to the result acquired in step S120 (step S130). Next, the short-circuit detection unit 63 determines whether the amplitude ratio of the third-order component is greater than the amplitude ratio of the first-order component (step S140). In step S140, when the amplitude ratio of the third-order component is greater than the amplitude ratio of the first-order component, the short-circuit detection unit 63 determines that a short circuit has occurred in the stator core 21, outputs information indicating "a short circuit has occurred" to the display device 70, and ends the current process (step S150). In addition, in step S140, if the result is negative, the short-circuit detection unit 63 outputs information indicating "no short circuit has occurred" to the display device 70 and ends the current process (step S160).

[0048] As described above, the short-circuit detection method of this embodiment includes a signal acquisition step shown in step S110, a signal decomposition step shown in step S120, and a short-circuit detection step shown in steps S130 to S160.

[0049] In the signal acquisition step, a voltage signal for one unit (one electrical angular cycle) from the detection coil 50 disposed opposite to the rotor 30 is acquired. In the signal decomposition step, the voltage signal acquired in the signal acquisition step is decomposed into a plurality of frequency components with different orders from each other. In the short-circuit detection step, based on the voltage signals of two units obtained at different time points, namely the voltage signal in the previous process and the voltage signal in the current process, the amplitude ratios of the odd-order low harmonic components (in this case, the third-order component) and the amplitude ratio of the fundamental component are calculated according to the amplitudes of the respective order components obtained in the signal decomposition step. Then, in the short-circuit detection step, when the amplitude ratio of the third-order component is greater than the amplitude ratio of the fundamental component, it is determined that a short circuit has occurred in the stator core 21. In addition, when the amplitude ratio of the fundamental component is equal to or less than the amplitude ratio of the third-order component, it is determined that no short circuit has occurred in the stator core 21.

[0050] As described above, the short-circuit detection device 100 of the present embodiment compares the amplitude ratio of the odd-order low harmonic component with the amplitude ratio of the fundamental frequency component based on the voltage signals of two units obtained at different time points, thereby determining the short circuit of the stator core 21. Therefore, when the turbo generator 10 operates in a state where the magnetic flux density of the stator core 21 is relatively high, the occurrence of a short circuit in the stator core 21 can be detected with high precision. In addition, when the turbo generator 10 operates in a state where the magnetic flux density of the stator core 21 is low, since it is difficult to detect the change in the amplitude of the harmonic components before and after the occurrence of a short circuit in the stator core 21, the accuracy of short-circuit detection is reduced. In this case, the turbo generator 10 operates at a low load, and even if a short circuit occurs between the laminations of the stator core 21, a large short-circuit current will not flow, and no problematic failure will occur.

[0051] In the short-circuit detection step of the above-described embodiment, based on the voltage signal obtained in the current process, the occurrence of a short circuit in the stator core 21 is re-detected. The other voltage signal of the two units is not limited to the voltage signal obtained in the previous process. In addition, since the stator core 21 and the fastener 83 are conductively short-circuited with a weak contact resistance, sometimes the contact portion is burned out due to the weak short-circuit current, thereby eliminating the short circuit. Since the short-circuit detection device 100 detects the occurrence of a short circuit in the stator core 21 by capturing the change in the voltage signals of two units obtained at different time points, the voltage signal obtained later does not necessarily need to be the voltage signal during the short circuit. Even if the previously obtained voltage signal is the voltage signal during the short circuit, the voltage signals of the two units, which are the voltage signal obtained after the short circuit is eliminated and the previously obtained voltage signal, can also detect the short circuit.

[0052] In addition, in the above-described embodiment, the short-circuit detection unit 63 uses the third harmonic component as the odd-order low-order harmonic component. However, when the amplitude ratio of at least one of the third harmonic component and the fifth harmonic component is greater than the amplitude ratio of the fundamental component, it is determined that a short circuit has occurred in the stator core 21. At this time, the amplitude ratio of the one with the larger amplitude among the third harmonic component and the fifth harmonic component can be compared with the amplitude ratio of the fundamental component. In the present embodiment, the determination is made by using the third harmonic component having the largest absolute value of the amplitude due to the influence of magnetic saturation, so that the signal-to-noise ratio of the amplitude ratio is good and the short-circuit determination can be performed with higher accuracy.

[0053] In addition, in the above-described embodiment, the rotor 30 is disposed on the inner peripheral side of the stator 20, but the rotor 30 may also be disposed on the outer peripheral side of the stator 20.

[0054] In addition, in the above-described embodiment, the turbogenerator 10 is used as the rotating electrical machine, but the rotating electrical machine may be a generator other than the turbogenerator 10, or may be a motor. In addition, the detection coil 50 is used as the magnetic detector, but the present invention is not limited thereto.

[0055] Incidentally, the functions of the signal processing device 60 of Embodiment 1 are implemented by a processing circuit. Figure 8 It is a structural diagram showing an example of the hardware for implementing the respective functions of the signal processing device 60. In this case, the signal processing device 60 is constituted by a processing circuit 60A as dedicated hardware.

[0056] In addition, the processing circuit 60A is implemented, for example, by 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.

[0057] In addition, Figure 9 It is a structural diagram showing another example of the hardware for implementing the respective functions of the signal processing device of Embodiment 1. In this case, the processing circuit 60B includes a processor 201 and a memory 202.

[0058] In the processing circuit 60B, the functions of the signal processing device 60 are implemented by software, firmware, or a combination of software and firmware. The software and firmware are denoted as programs and stored in the memory 202. The processor 201 reads the programs stored in the memory 202 and executes them, thereby implementing the respective functions.

[0059] The program stored in the memory 202 can also be said to be a program that causes a computer to execute the steps or methods of the above-mentioned respective parts. That is, this program is a short-circuit detection program, which is a program that causes a computer to execute signal acquisition processing, signal decomposition processing, and short-circuit detection processing.

[0060] Here, the memory 202 is equivalent to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. In addition, a magnetic disk, a floppy disk, an optical disk, a compact disk, a minidisk, a DVD, etc. are also equivalent to the memory 202.

[0061] In addition, for the functions of the above-mentioned signal processing device 60, a part can be implemented by dedicated hardware, and a part can be implemented by software or firmware.

[0062] Thus, the processing circuit can implement the functions of the above-mentioned signal processing device 60 by using hardware, software, firmware, or a combination thereof.

[0063] Embodiment 2. In the above Embodiment 1, the short-circuit detection unit 63 uses the amplitude ratio as the amplitude change of each frequency component of two units of voltage signals acquired at different time points, but the amplitude change amount itself can also be used. Figure 10 It is a diagram showing the amplitude change amount of each frequency component calculated by the short-circuit detection unit 63. If one n-th amplitude value is V1n and the other n-th amplitude value is V2n, the amplitude change amount ΔV is calculated as ΔV = |V1n - V2n|.

[0064] As Figure 10 shown, the amplitude change amounts of the third component and the fifth component, which are odd-order low-order harmonic components, are relatively large, significantly larger than the amplitude change amount of the first component. In particular, the amplitude change amount of the third component is relatively large. In addition, the amplitude changes of the high-order harmonic components of the seventh order and above are relatively small, showing the same trend as that of the above-mentioned Embodiment 1 using the amplitude ratio. Figure 6 the same trend. Further, the short - circuit detection unit 63 detects the occurrence of a short - circuit in the stator core 21 based on a comparison between the amplitude change amount of the fundamental component and the amplitude change amount of the third - harmonic component. For example, when the amplitude change amount of the third - harmonic component is significantly greater than the amplitude change amount of the fundamental component, the short - circuit occurrence in the stator core 21 is detected.

[0065] As described above, in the present embodiment, based on two sets of voltage signals acquired at different time points, the amplitude change amount of the odd - order low - harmonic components is compared with the amplitude change amount of the fundamental - frequency component, thereby determining the short - circuit of the stator core 21. Therefore, similar to the above - mentioned Embodiment 1, when the turbo - generator 10 operates in a state where the magnetic - flux density of the stator core 21 is relatively high, the occurrence of a short - circuit in the stator core 21 can be detected with high precision. In addition, since the amplitude change amount is used for short - circuit determination, the magnitude of the absolute value of the amplitude does not affect the signal - to - noise ratio. Therefore, the short - circuit can be detected with high precision without deleting the frequency components with a small absolute value of the amplitude.

[0066] Embodiment 3. In the above - mentioned Embodiment 1 and Embodiment 2, the signal decomposition unit 62 decomposes the voltage signal acquired by the signal acquisition unit 61 into respective frequency components, and the short - circuit detection unit 63 performs short - circuit detection based on the results of the signal decomposition unit 62 decomposing the two sets of voltage signals respectively. In this Embodiment 3, the signal decomposition unit 62 decomposes the differential signal of the two sets of voltage signals acquired by the signal acquisition unit 61 at different time points into respective frequency components, and the short - circuit detection unit 63 performs short - circuit detection based on the results of the signal decomposition unit 62 decomposing the differential signal.

[0067] Figure 11 is a diagram showing the differential signal of two different voltage signals acquired by the signal acquisition unit 61. This differential signal represents the voltage waveform that is the difference between the voltage signal (voltage waveform in the healthy state) shown as Figure 2 and the voltage signal (voltage waveform in the short - circuit state) shown as Figure 3 . The signal decomposition unit 62 decomposes the differential signal of the two sets of voltage signals into a plurality of frequency components with different orders from each other, and further separates each decomposed frequency component into amplitude and phase. The amplitude of each frequency component in the differential signal represents the amplitude change when the two sets of voltage signals are respectively frequency - decomposed.

[0068] The short - circuit detection unit 63 compares the amplitude of the odd - order harmonic components decomposed by the signal decomposition unit 62 with the amplitude of the fundamental - frequency component. Figure 12It is a spectrogram showing the amplitude ratios of the respective frequency components calculated by the short-circuit detection unit 63, and the ratio (%) of the amplitude of each odd-numbered frequency component to the amplitude of the fundamental frequency component is expressed as the amplitude ratio. In this case, similarly to the first embodiment, the components of the fifth, eleventh, and seventeenth orders with relatively small absolute values of the amplitude are excluded from the calculation. When the amplitude value of the fundamental frequency component is Va1 and the amplitude value of the n-th component is Van, the amplitude ratio Ra is calculated as |Van / Va1|×100, with the unit of %.

[0069] As Figure 12 shown, the amplitude of the third-order component is significantly larger than the amplitude of the fundamental frequency component. The amplitude of each frequency component of the differential signal represents the amplitude change of each frequency component of the voltage signal of two units, and shows the same trend as that in the above-mentioned first embodiment and second embodiment. Figure 6 and Figure 10 That is, the amplitude of the third-order component is particularly large, while the amplitudes of the harmonic components of the seventh order and higher are small. Based on the comparison between the amplitude of the fundamental component and the amplitude of the third-order component, the short-circuit detection unit 63 detects the occurrence of a short circuit in the stator core 21, for example, when the amplitude of the third-order component is significantly larger than the amplitude of the fundamental component.

[0070] As described above, in the present embodiment, the signal decomposition unit 62 decomposes the differential signal of the voltage signals of two units obtained at different time points into a plurality of frequency components with different orders from each other. Then, the short-circuit detection unit 63 performs short-circuit detection based on the result of decomposing the differential signal by the signal decomposition unit 62. At this time, the amplitude of the fundamental frequency component in the differential signal that becomes the amplitude change of the fundamental frequency component of the voltage signals of two units is compared with the amplitude of the low-order harmonic component in the differential signal that becomes the amplitude change of the low-order harmonic component, thereby determining the short circuit of the stator core 21.

[0071] Therefore, similarly to the first embodiment described above, when the turbo generator 10 operates in a state where the magnetic flux density of the stator core 21 is relatively high, the occurrence of a short circuit in the stator core 21 can be detected with high accuracy. In addition, since the signal decomposition unit 62 inputs the differential signal of the voltage signals of two units and performs frequency decomposition on it, the number of signals to be processed can be halved, thereby reducing the processing load.

[0072] This application describes various exemplary embodiments and examples, but the various features, forms, and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can be applied to the embodiments alone or in various combinations. Therefore, countless unillustrated variations can be envisioned within the scope of the technology disclosed in the present application. For example, it is assumed to include cases where at least one component is deformed, added, or omitted, and cases where at least one component is extracted and combined with components of other embodiments. Reference Signs Explanation

[0073] 10 Turbine generator (rotating electrical machine), 20 Stator, 21 Stator core, 30 Rotor, 50 Detection coil (magnetic detector), 61 Signal acquisition unit, 62 Signal decomposition unit, 63 Short-circuit detection unit, 100 Short-circuit detection device.

Claims

1. A short-circuit detection device for a rotating electrical machine, characterized in that, comprising: a signal acquisition unit that acquires a voltage signal from a magnetic detector disposed opposite to the rotor of the rotating electrical machine on the stator side; a signal decomposition unit that decomposes the voltage signal into a plurality of frequency components having different orders from each other based on the voltage signal; and a short-circuit detection unit that determines a short circuit of a stator core formed by lamination based on odd-order low-order harmonic components and fundamental frequency components among the frequency components decomposed by the signal decomposition unit, wherein the signal acquisition unit acquires the voltage signal in units of one electrical angular cycle, and the short-circuit detection unit detects changes in the amplitudes of the low-order harmonic components and the fundamental frequency components respectively based on two units of the voltage signals acquired at different time points, and determines the short circuit of the stator core based on a comparison between the change in the amplitude of the low-order harmonic component and the change in the amplitude of the fundamental frequency component.

2. The short-circuit detection device for a rotating electrical machine according to claim 1, characterized in that, when the change in the amplitude of the low-order harmonic component is greater than the change in the amplitude of the fundamental frequency component, the short-circuit detection unit determines the short circuit of the stator core.

3. The short-circuit detection device for a rotating electrical machine according to claim 1 or 2, characterized in that, the signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into a plurality of frequency components having different orders from each other, and the short-circuit detection unit compares the change in the amplitude of the fundamental frequency component with the change in the amplitude of the low-order harmonic component based on the results of decomposing two units of the voltage signals by the signal decomposition unit.

4. The short-circuit detection device for a rotating electrical machine according to claim 1 or 2, characterized in that, the signal decomposition unit decomposes a differential signal of two units of the voltage signals into a plurality of frequency components having different orders from each other, and the short-circuit detection unit compares the amplitude of the fundamental frequency component in the differential signal that becomes the change in the amplitude of the fundamental frequency component with the amplitude of the low-order harmonic component in the differential signal that becomes the change in the amplitude of the low-order harmonic component based on the results of decomposing the differential signal by the signal decomposition unit.

5. The short-circuit detection device for a rotating electrical machine according to any one of claims 1 to 4, characterized in that, the short-circuit detection unit uses at least one of a third-order frequency component and a fifth-order frequency component as the low-order harmonic component.

6. The short-circuit detection device for a rotating electrical machine according to any one of claims 1 to 5, characterized in that, the short-circuit detection unit calculates and uses an amplitude ratio as the change in amplitude.

7. A short-circuit detection method for a rotating electrical machine, characterized in that, comprising: a signal acquisition step of acquiring a voltage signal from a magnetic detector disposed opposite to the rotor of the rotating electrical machine on the stator side; a signal decomposition step of decomposing the voltage signal into a plurality of frequency components having different orders from each other based on the voltage signal; and A short-circuit detection step for determining a short circuit in a laminated stator core based on odd-order low-order harmonic components and fundamental frequency components among the frequency components decomposed in the signal decomposition step. In the signal acquisition step, the voltage signal is acquired with one electrical angular cycle as one unit. In the short-circuit detection step, the amplitude changes of the low-order harmonic components and the amplitude changes of the fundamental frequency components are respectively detected based on two units of the voltage signal acquired at different time points, and the short circuit of the stator core is determined based on the comparison between the amplitude changes of the low-order harmonic components and the amplitude changes of the fundamental frequency components.

8. The short-circuit detection method for a rotating electrical machine according to claim 7. Characterized in that In the signal acquisition step, with one electrical angular cycle as one unit, the voltage signal is repeatedly acquired at different time points. In the short-circuit detection step, the short circuit of the stator core is determined based on two units of the voltage signal acquired last time and two units of the voltage signal acquired this time.

Images