Apparatus and method for detecting short circuit in rotating electrical machine

Abstract

This short circuit detection device (100) for a rotating electric machine (10) comprises 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 a voltage signal from the signal acquisition unit (61) into a plurality of frequency components different from one another in order. The short circuit detection unit (63) makes a comparison between an amplitude change in an odd low harmonic component and an amplitude change in a first-order frequency component from an output result of the signal decomposition unit (62) based on two units of the voltage signals acquired at different time points to determine a short circuit of the stator core (21).

Description

[Technical Field]

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

[0002] In a stator core of a rotating electric machine that uses a laminated core, a short circuit may occur between laminations via an axial fastener. If a large short-circuit current flows between laminations of the stator core, problems such as increased heat loss, increased vibration of the rotating electric machine, or an imbalance in the three-phase current output by the rotating electric machine may occur. In particular, when a rotating electric machine is operated under high load, the magnetic flux density within the rotating electric machine is high, and if a short circuit occurs between the laminations of the stator core, the balance of each frequency component of the magnetic flux density changes significantly.

[0003] In the prior art described in Patent Document 1, a rotating electric machine in which a rotor holding a field winding and a stator are separated by a gap is provided with a device for monitoring the field magnetic flux in the gap and a device for detecting the presence of even harmonics in this magnetic flux wave.Faults in the rotating electric machine are detected by detecting the even harmonics of the voltage induced in a search coil placed in the gap. Furthermore, the prior art described in Patent Document 2 describes that when magnetic flux generated in a rotating electric machine is affected by magnetic saturation, odd-order harmonic currents flow through the stator windings, and the magnetic field created by these currents creates harmonic magnetic flux within the rotating electric machine.The document also describes that improvements to the stator core structure can suppress the generation of harmonic currents due to magnetic saturation, thereby reducing vibration and electromagnetic noise in the rotating electric machine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 53-84101 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-130839 Summary of the Invention [Problem to be solved by the invention]

[0005] The prior art described in Patent Document 1 can detect short circuits in the rotor field winding by detecting even harmonics of the voltage induced in the search coil, but cannot detect short circuits between laminations in the stator core. Furthermore, the prior art described in Patent Document 2 alleviates the adverse effects of magnetic saturation, but does not take into consideration the detection of short circuits between laminations of the stator core. Therefore, even if a short circuit occurs between laminations of the stator core while the rotating electric machine is operating in a state where the magnetic flux density of the stator core is relatively high, there has been a problem in that the occurrence of the short circuit cannot be detected accurately.

[0006] The present application discloses technology for solving the above-mentioned problems, and aims to provide a short circuit detection device and a short circuit detection method for a rotating electric machine that can accurately detect short circuits that occur between laminations of a stator core while the rotating electric machine is operating in a state where the magnetic flux density of the stator core is relatively high. [Means for solving the problem]

[0007] The present disclosure provides a short-circuit detection device for a rotating electric machine, comprising: a signal acquisition unit that acquires a voltage signal from a magnetic detector disposed on the stator side facing the rotor of the rotating electric machine; a signal decomposition unit that decomposes the voltage signal into a plurality of frequency components of different orders; and a short-circuit detection unit that determines whether a laminated stator core is short-circuited based on odd-order low-order harmonic components and a first-order frequency component among the frequency components decomposed by the signal decomposition unit. The signal acquisition unit acquires the voltage signal in units of one electrical angle cycle. The short-circuit detection unit detects amplitude changes in the low-order harmonic components and the first-order frequency component based on two units of the voltage signal acquired at different times, and determines whether the stator core is short-circuited based on a comparison of the amplitude changes in the low-order harmonic components and the first-order frequency component.

[0008] The present application also discloses a method for detecting a short circuit in a rotating electric machine, comprising: a signal acquiring step of acquiring a voltage signal from a magnetic detector disposed on the stator side facing the rotor of the rotating electric machine; a signal decomposition step of decomposing the voltage signal into a plurality of frequency components of different orders; and a short circuit detection step of determining a short circuit in a laminated stator core based on odd-order low-order harmonic components and a first-order frequency component among the frequency components decomposed in the signal decomposition step. The signal acquiring step acquires the voltage signal in units of one electrical angle cycle. The short circuit detection step detects amplitude changes in the low-order harmonic components and the first-order frequency component based on two units of the voltage signal acquired at different times, and determines a short circuit in the stator core based on a comparison of the amplitude changes in the low-order harmonic components and the first-order frequency component. [Effects of the Invention]

[0009] The short circuit detection device and short circuit detection method for a rotating electric machine disclosed in the present application can accurately detect short circuits that occur between laminations of the stator core while the rotating electric machine is operating in a state where the magnetic flux density of the stator core is relatively high. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a configuration diagram showing a rotating electric machine and a short-circuit detection device according to a first embodiment. [Figure 2] 4 is a waveform diagram showing a voltage signal acquired by a signal acquiring section in accordance with the first embodiment when the device is in a healthy state. FIG. [Figure 3] 4 is a waveform diagram showing a voltage signal acquired by a signal acquiring section in accordance with the first embodiment during a short circuit. FIG. [Figure 4] FIG. 4 is a diagram showing a magnetic flux density distribution when the stator core is short-circuited according to the first embodiment. [Figure 5] 4A and 4B are spectral diagrams showing the amplitudes of odd-order components in a healthy state and in a short-circuit state among the frequency components decomposed by the signal decomposing unit according to the first embodiment. [Figure 6]5 is a diagram showing the amplitude ratio of each frequency component calculated by the short circuit detection unit according to the first embodiment. FIG. [Figure 7] FIG. 3 is a flowchart illustrating a short-circuit detection method according to the first embodiment. [Figure 8] 1 is a configuration diagram showing an example of hardware for realizing each function of a signal processing device according to a first embodiment. [Figure 9] FIG. 4 is a configuration diagram showing another example of hardware for realizing each function of the signal processing device according to the first embodiment. [Figure 10] 10 is a diagram showing the amount of change in amplitude of each frequency component calculated by the short circuit detector according to the second embodiment. FIG. [Figure 11] 10 is a diagram showing a differential signal between two different voltage signals acquired by a signal acquisition unit according to the third embodiment. FIG. [Figure 12] FIG. 11 is a spectrum diagram showing the amplitude ratio of each frequency component calculated by the short circuit detection unit according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiment 1 Hereinafter, embodiments will be described with reference to the drawings. Fig. 1 is a configuration diagram showing a rotating electric machine and a short-circuit detection device according to embodiment 1. In embodiment 1, a turbine generator 10 is employed as the rotating electric machine. Fig. 1 shows a cross section perpendicular to the axial direction of the turbine generator 10.

[0012] 1, the turbine generator 10 includes a stator 20 as an armature and a rotor 30 as a field magnet. The stator 20 is provided outside the rotor 30. The stator 20 has a cylindrical stator core 21 and a multi-phase winding 22 (not shown), and a plurality of stator slots 23 are formed in the inner periphery 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 the direction perpendicular to the plane of the paper in Fig. 1. 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 stator slot 23 formed in the inner periphery of the stator core 21 is provided along the radial direction of the stator core 21. The multiple stator slots 23 are arranged at equal pitches in the circumferential direction of the stator core 21. Multi-phase windings 22 are wound in the multiple stator slots 23.

[0014] The stator core 21 has a laminated structure formed by stacking steel plates, and fasteners 81 and 82 are provided inside and on the outer periphery of the stator core 21, and the fasteners 81 and 82 each penetrate the stator core 21 to hold the laminated stator core 21 in place.

[0015] The rotor 30 has a rotor core 31, a field winding 32 (not shown), 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 is rotatable around the rotating shaft. A plurality of 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. 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 pitches in the circumferential direction of the rotor core 31.

[0016] The field winding 32 is DC excited by an external power supply (not shown), causing one of the first magnetic pole 34 and the second magnetic pole 35 to become an N pole and the other to become an S pole. In other words, the turbine 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 multi-phase windings 22 are AC excited by an external power source (not shown), which generates a rotating magnetic field within the air gap 40.

[0018] The short circuit detection device 100 detects short circuits between laminations of the stator core 21 of the turbine generator 10, and includes a search coil 50 as a magnetic detector, a signal processing device 60 that processes detection signals from the search coil 50, and a display device 70. The search coil 50 is disposed in the air gap 40 facing the rotor 30. The search coil 50 may be arranged facing the rotor 30 inside the stator core 21, including the stator slot 23 close to the air gap 40. That is, the search coil 50 is arranged facing the rotor 30 on the side of the stator 20 that includes the air gap 40.

[0019] Main magnetic flux and leakage magnetic flux are linked to the search coil 50. The main magnetic flux is magnetic flux generated in the air gap 40, and the leakage magnetic flux is magnetic flux leaking from each rotor slot 33. The magnetic flux that links to the search coil 50 is called flux linkage.

[0020] The search coil 50 has a first terminal 51 and a second terminal 52. When magnetic flux is linked to the search coil 50, a voltage signal, which is a detection signal, is induced between the first terminal 51 and the second terminal 52. The distribution of the linked magnetic flux in the search coil 50 varies as the rotor 30 rotates. In this case, the short circuit detection device 100 is provided with the search coil 50 as a magnetic detector, but the search coil 50 may 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 a voltage signal induced in the search coil 50. The signal decomposition unit 62 decomposes the acquired voltage signal into a plurality of frequency components of different orders. The voltage signal acquired by the signal acquisition unit 61 is handled in units of one electrical angle cycle. The signal decomposition unit 62 decomposes the voltage signal for one electrical angle cycle into each frequency component. Furthermore, the signal decomposition unit 62 separates each of the decomposed frequency components into amplitude and phase.

[0022] The short circuit detection unit 63 analyzes the amplitude of the odd-order frequency components among the resolved frequency components. The odd-order frequency components are composed of a fundamental wave component, which is a first-order component that oscillates once per electrical angle cycle corresponding to the two poles, the first magnetic pole 34 and the second magnetic pole 35, and third-order and higher harmonic components other than the first-order component. The short circuit detection unit 63 determines whether a short circuit has occurred in the laminated stator core 21 based on the odd-order lower harmonic components and the first-order component.

[0023] If there is no change in the operating state of the turbine generator 10 and no short circuit has occurred in the stator core 21, the amplitude of each odd-order frequency component decomposed by the signal decomposing unit 62 remains unchanged. Furthermore, even if there is no change in the operating state of the turbine generator 10, a short circuit occurs in the stator core 21, and the short circuit state remains constant, the amplitude of each odd-order frequency component decomposed by the signal decomposition unit 62 remains unchanged.

[0024] On the other hand, even if there is no change in the operating state of the turbine generator 10, the amplitudes of the odd-order frequency components decomposed by the signal decomposition unit 62 will not be the same between the voltage signal for one electrical angle cycle acquired before the occurrence of a short circuit in the stator core 21 and the voltage signal for one electrical angle cycle acquired after the occurrence of a short circuit. In other words, when a change in amplitude is observed between the voltage signals of two units, each acquired for one unit (one electrical angle cycle) at different points in time, in the odd-order frequency components obtained by frequency decomposition of the voltage signals of two units, a short circuit in the stator core 21 can be detected.

[0025] The two-unit voltage signal is acquired by the signal acquisition unit 61 either continuously or intermittently at time intervals, with the voltage waveform acquired one unit at a time. When an amplitude change is observed in each odd-order frequency component between the two-unit voltage signal, that is, the previous voltage signal acquired before the short circuit occurred and the newly acquired voltage signal, the occurrence of a new short circuit in the stator core 21 can be detected.

[0026] The short circuit detection unit 63 calculates the amplitude ratio as the change in amplitude of each odd-order frequency component of two units of voltage signals when the turbine generator 10 is in the same operating state. In this embodiment, if 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 detects that a short circuit has occurred in the stator core 21.

[0027] Furthermore, the short circuit detection unit 63 outputs information on whether or not the stator core 21 is short-circuited to the display device 70.

[0028] The display device 70 is provided outside the signal processing device 60. The display device 70 displays whether or not the stator core 21 is short-circuited based on information from the short-circuit detection unit 63. The display device 70 may be provided outside the short circuit detection device 100.

[0029] Fig. 2 is a waveform diagram showing a voltage signal in a healthy state acquired by the signal acquiring unit 61. Fig. 3 is a waveform diagram showing a voltage signal in a short-circuit state acquired by the signal acquiring unit 61. 2 and 3 show examples of voltage signals when the device is healthy and when a short circuit occurs, with the horizontal axis representing one period of electrical angle corresponding to two poles, the first magnetic pole 34 and the second magnetic pole 35. FIG. 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 when the voltage signal of FIG. 3 is acquired.

[0030] 2 to 4 were obtained by simulating a no-load operating state in which the turbine generator 10 generates the rated voltage using an electromagnetic field analysis program. The simulation of a short circuit is performed under the condition that the stator core 21 is short-circuited via fasteners 83 that penetrate and hold the stator core 21 inside or on the outer periphery of the stator core 21. In this case, fasteners 81A that are placed inside the stator core 21 at the same circumferential position as the search coil 50 shown in Fig. 1, and fasteners 82A that are placed on both sides of fastener 81A in the circumferential position on the outer periphery of the stator core 21, are the fasteners 83 that form the short circuit.

[0031] When detecting a short circuit in the stator core 21, it is important to quickly detect when a short circuit causes a large short-circuit current to flow between the laminations of the stator core 21. For this reason, the simulation of a short circuit was set under conditions where the distance between the fasteners 83 that make up the short circuit is short, making it easy for a large short-circuit current to flow.

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

[0033] 2 and 3 are voltage waveforms for one electrical angle cycle, with circumferential angles from 0° to 180° corresponding to the first magnetic pole 34 and circumferential angles from 180° to 360° corresponding 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 search coil 50, and at a circumferential angle of 270°, the center of the second magnetic pole 35 is closest to the search coil 50.

[0034] The voltage waveform shown in Figure 2 is a voltage waveform when there is no short circuit and the circuit is healthy, with 32 small voltage fluctuations occurring at each rotor slot pitch. The voltage waveform shown in Figure 3 is the voltage waveform when a short circuit occurs, and although the amplitude of the harmonic components increases as will be described later, the waveform as a whole is almost the same as that in Figure 2.

[0035] As described above, the signal decomposition unit 62 decomposes the voltage signal acquired by the signal acquisition unit 61 into multiple frequency components of different orders, and further separates each of the decomposed frequency components into amplitude and phase. Fig. 5 is a spectrum diagram showing the amplitudes of odd-order components in a healthy state and in a short-circuit state among the frequency components decomposed by the signal decomposition unit 62. That is, Fig. 5 shows the amplitude spectrum of the odd-order components based on the voltage waveform shown in Fig. 2 and the amplitude spectrum of the odd-order components based on the voltage waveform shown in Fig. 3 side by side so that absolute values ​​can be easily compared. Furthermore, although orders of 21 and above exist, Fig. 5 shows orders of 19 and below for the sake of explanation.

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

[0037] 4, in region A surrounded by fasteners 81A and 82A short-circuited to stator core 21, magnetic shielding reduces the magnetic flux density. In contrast, in region B, which includes region B1 radially inward of region A and region B2 opposite region A with respect to the axis, the magnetic flux density increases due to the magnetic flux being diverted by the shielding. The magnetic flux density increases in the center of the magnetically saturated region, and the magnetic flux density in the peripheral region also increases, widening the magnetically saturated region and increasing harmonic components.

[0038] The detouring magnetic flux takes a detour around half a circle, as in region B, and since it causes spatial fluctuations in two or four places on either the core back or teeth side, it appears not as a change in first- or higher-order magnetic flux density, but mainly as a change in lower-order magnetic flux density, such as third or fifth order.The effects of magnetic saturation also appear as harmonic components at frequencies that are multiples of two or four, but the higher the frequency, the smaller the voltage value becomes.

[0039] Basically, the change in permeance is second order and the change in magnetomotive force is first order, so the change in magnetic flux density, which is the difference between them, is third order. If the permeance change has a fourth order component as a harmonic, the change in magnetic flux density will be third or fifth order. Similarly, harmonics of even higher frequencies will be included.

[0040] The short circuit detection unit 63 calculates the amplitude ratio between the same lower orders of the odd-order harmonic components decomposed by the signal decomposition unit 62 . FIG. 6 is a diagram showing the amplitude ratio of each frequency component calculated by the short circuit detection unit 63, and is calculated from the spectrum diagram of FIG. In FIG. 5, the 5th, 11th, and 17th order components, which have relatively small absolute amplitude values, are excluded from the calculation because they have a poor signal-to-noise ratio (SN ratio) of the amplitude ratio.

[0041] For example, if one nth-order amplitude value is V1n and the other nth-order amplitude value is V2n, the amplitude ratio R is calculated as R = (|V1n - V2n| / V1n) x 100, in %, as a percentage. The magnetic saturation region expands as a result of a short circuit. When there is no short circuit, the amplitude ratio is nearly 0, but when a short circuit occurs, the amplitude ratio changes. The first and seventh and higher order frequency components are relatively little affected by magnetic saturation and have small amplitude ratios. In contrast, the third and fifth order frequency components, which are low-order harmonic components, are significantly affected by magnetic saturation due to a short circuit and have large amplitude ratios.

[0042] In this case, the fifth-order component has been excluded, and it can be seen that the amplitude ratio of the third-order component is large. Generally, the magnitude of the amplitude of the third-order component and the fifth-order component will depend on the phase of the two components, with one being large and the other being small, or both being medium and balanced.

[0043] As shown in Figure 6, the amplitude ratio of the higher-order frequency components is 0.0 to 1.2%, while the amplitude ratio of the third-order component is about 5%, which is significantly greater than 1.2%. The amplitude ratio of the first-order component is a relatively small 0.2%, and the amplitude ratio of the third-order component is significantly larger than the amplitude ratio of the first-order component. Based on a comparison between the amplitude ratio of the first-order component and the amplitude ratio of the third-order component, for example, when the amplitude ratio of the third-order component is clearly greater than the amplitude ratio of the first-order component, the short-circuit detection unit 63 detects the occurrence of a short circuit in the stator core 21. The determination that the amplitude ratio is clearly greater may be made, for example, when the difference or ratio is greater than a set value.

[0044] By making a judgment using the third-order component, which has the largest absolute value of the amplitude ratio due to the influence of magnetic saturation of the stator core 21, the signal-to-noise ratio of the amplitude ratio is improved, and a short circuit can be judged with higher accuracy. When the stator core 21 is magnetically saturated, the amplitude of the harmonic components is larger than when it is not magnetically saturated, so the amplitude ratio of the harmonic components before and after a short circuit occurs in the stator core 21 can be analyzed with a good signal-to-noise ratio. For this reason, a state in which the turbine generator 10 is operating at a high magnetic flux density is suitable for detecting a short circuit in the stator core 21.

[0045] Next, the short circuit detection method according to this embodiment will be described below with reference to the drawings. 7 is a flowchart illustrating a short circuit detection method according to embodiment 1. When the short circuit detection device 100 is activated, the signal processing device 60 executes a short circuit detection routine shown in the flowchart of FIG.

[0046] When the short circuit detection routine is started, first, the signal acquisition unit 61 acquires a voltage signal of one unit (one electrical angle cycle) from the search coil 50 (step S110). Next, the signal decomposing unit 62 decomposes the acquired voltage signal into a plurality of frequency components of different orders, and separates the signal into amplitude and phase (step S120).

[0047] Next, the short circuit detection unit 63 calculates the amplitude ratio of each odd-order frequency component from the results obtained in step S120 based on two units of voltage signals, the voltage signal obtained in the previous routine and the voltage signal obtained in the current routine (step S130). Next, the short circuit detecting 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 that a short circuit has occurred to the display device 70, and ends the current routine (step S150). If the result of step S140 is NO, the short circuit detection unit 63 outputs information indicating "no short circuit has occurred" to the display device 70 and ends the current routine (step S160).

[0048] As described above, the short circuit detection method according to 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 of one unit (one electrical angle cycle) is acquired from the search coil 50 arranged opposite the rotor 30. In the signal decomposition step, the voltage signal acquired in the signal acquisition step is decomposed into a plurality of frequency components of different orders. In the short-circuit detection step, the amplitude ratio of the odd-order low-order harmonic component (in this case, the third-order component) and the amplitude ratio of the first-order component are calculated from the amplitudes of each order component obtained in the signal decomposition step based on two unit voltage signals acquired at different times: the voltage signal in the previous routine and the voltage signal in the current routine. Then, in the short-circuit detection step, if the amplitude ratio of the third-order component is greater than the amplitude ratio of the first-order component, it is determined that a short circuit has occurred in the stator core 21. Furthermore, if the amplitude ratio of the first-order component is the same as or smaller 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 according to this embodiment compares the amplitude ratio of the odd-order low-order harmonic components with the amplitude ratio of the primary frequency component based on two unit voltage signals acquired at different times to determine whether a short circuit has occurred in the stator core 21. This makes it possible to accurately detect the occurrence of a short circuit in the stator core 21 while the turbine generator 10 is operating in a state where the magnetic flux density of the stator core 21 is relatively high. If the turbine generator 10 is operating with a low magnetic flux density in the stator core 21, the accuracy of short-circuit detection will be reduced because it is difficult to detect changes in the amplitude of harmonic components before and after a short circuit occurs in the stator core 21. In this case, the turbine generator 10 is operating at a low load, and even if a short circuit occurs between the laminations of the stator core 21, no large short-circuit current will flow, and no problematic malfunction will occur.

[0051] The short circuit detection step in the above embodiment newly detects the occurrence of a short circuit in the stator core 21 based on the voltage signal acquired in the current routine. The other voltage signal of the two units is not limited to the voltage signal acquired in the previous routine. Furthermore, since the stator core 21 and the fastener 83 are electrically connected with a slight contact resistance and short-circuited, a slight short-circuit current may burn out the contact portion and resolve the short circuit. Since the short-circuit detection device 100 detects the occurrence of a short circuit in the stator core 21 by capturing changes in two units of voltage signals acquired at different times, it is not necessary that the voltage signal acquired later is the one at the time of the short circuit. A short circuit can be detected even if the voltage signal acquired earlier is the one at the time of the short circuit and the voltage signal acquired after the short circuit has been resolved is the two-unit voltage signal.

[0052] In the above embodiment, the short-circuit detection unit 63 uses the third-order component as the odd-order low-order harmonic component, but if the amplitude ratio of at least one of the third-order and fifth-order components is greater than the amplitude ratio of the first-order component, it determines that a short circuit has occurred in the stator core 21. In this case, it is also possible to compare the amplitude ratio of the third-order or fifth-order component, whichever has the greater amplitude ratio, with the amplitude ratio of the first-order component. In this embodiment, by making the determination using the third-order component, which has the largest absolute value of amplitude due to the influence of magnetic saturation, the signal-to-noise ratio of the amplitude ratio is improved, allowing for more accurate short-circuit detection.

[0053] Furthermore, in the above embodiment, the rotor 30 is disposed on the inner circumferential side of the stator 20 , but the rotor 30 may be disposed on the outer circumferential side of the stator 20 .

[0054] Furthermore, in the above embodiment, the turbine generator 10 is used as the rotating electrical machine, but the rotating electrical machine may be a generator other than the turbine generator 10, or may be an electric motor. Furthermore, although the search coil 50 is used as the magnetic detector, the present invention is not limited to this.

[0055] The functions of the signal processing device 60 according to the first embodiment are realized by a processing circuit. 8 is a configuration diagram showing an example of hardware that realizes each function of the signal processing device 60. In this case, the signal processing device 60 is configured by a processing circuit 60A that is dedicated hardware.

[0056] Furthermore, the processing circuit 60A may be, for example, 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] 9 is a configuration diagram showing another example of hardware for realizing each function of the signal processing device 60 according to the 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 realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 202. The processor 201 realizes each function by reading and executing the programs stored in the memory 202.

[0059] It can also be said that the program stored in memory 202 causes a computer to execute the procedures or methods of the above-mentioned parts. In other words, this program is a short-circuit detection program, and causes a computer to execute signal acquisition processing, signal decomposition processing, and short-circuit detection processing.

[0060] Here, the memory 202 refers to non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable and Programmable Read Only Memory), etc. In addition, the memory 202 also includes magnetic disks, flexible disks, optical disks, compact disks, mini disks, DVDs, etc.

[0061] It should be noted that the functions of the signal processing device 60 described above may be partially realized by dedicated hardware and partially realized by software or firmware.

[0062] In this way, the processing circuitry can realize the functions of the signal processing device 60 described above by hardware, software, firmware, or a combination thereof.

[0063] Embodiment 2 In the first embodiment, the short circuit detecting unit 63 uses the amplitude ratio as the amplitude change of each frequency component of two units of voltage signals acquired at different times, but the amplitude change amount itself may be used. FIG. 10 is a diagram showing the amount of change in amplitude of each frequency component calculated by the short circuit detection unit 63. In FIG. When one n-th order amplitude value is V1n and the other n-th order amplitude value is V2n, the amplitude change amount ΔV is calculated as ΔV=|V1n−V2n|.

[0064] As shown in Figure 10, the amplitude change amounts of the odd-order low-order harmonic components, the third and fifth order components, are large and significantly larger than the amplitude change amount of the first order component. The amplitude change amount of the third order component is particularly large. Furthermore, the amplitude change amounts of the seventh and higher order harmonic components are small, showing the same tendency as in Figure 6 of the first embodiment using the amplitude ratio. The short circuit detection unit 63 then detects the occurrence of a short circuit in the stator core 21 based on a comparison between the amplitude change of the first-order component and the amplitude change of the third-order component, for example, when the amplitude change of the third-order component is clearly greater than the amplitude change of the first-order component.

[0065] As described above, in this embodiment, based on two units of voltage signals acquired at different times, the amount of change in amplitude of the odd-order low-order harmonic components is compared with the amount of change in amplitude of the primary frequency component to determine whether or not there is a short circuit in the stator core 21. Therefore, similar to the first embodiment, it is possible to accurately detect the occurrence of a short circuit in the stator core 21 while the turbine generator 10 is operating in a state where the magnetic flux density of the stator core 21 is relatively high. Furthermore, since the amount of change in amplitude is used to determine whether a short circuit is occurring, the magnitude of the absolute amplitude value does not affect the signal-to-noise ratio, making it possible to accurately detect short circuits without removing order components with small absolute amplitude values.

[0066] Embodiment 3 In the above-mentioned first and second embodiments, the signal decomposition unit 62 decomposed the voltage signal acquired by the signal acquisition unit 61 into each frequency component, and the short circuit detection unit 63 performed short circuit detection based on the results of decomposition of two units of voltage signal by the signal decomposition unit 62. In this embodiment 3, the signal decomposition unit 62 decomposes the differential signal of two units of voltage signals acquired by the signal acquisition unit 61 at different times into each frequency component, and the short circuit detection unit 63 performs short circuit detection based on the result of the decomposition of the differential signal by the signal decomposition unit 62.

[0067] Fig. 11 is a diagram showing a differential signal between two different voltage signals acquired by the signal acquiring unit 61. This differential signal shows a voltage waveform that is the difference between the voltage signal shown in Fig. 2 (voltage waveform in a healthy state) and the voltage signal shown in Fig. 3 (voltage waveform in a short circuit state). The signal decomposition unit 62 decomposes the differential signal of the two-unit voltage signals into multiple frequency components of different orders, and further separates each of the decomposed frequency components into amplitude and phase. The amplitude of each frequency component in the differential signal represents the amplitude change when the two-unit voltage signals are 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 first-order frequency component. 12 is a spectrum diagram showing the amplitude ratio of each frequency component calculated by the short circuit detection unit 63, and the amplitude ratio is expressed as the ratio (%) of the amplitude of each odd-order frequency component to the amplitude of the first-order frequency component. In this case, as in the first embodiment, the 5th-, 11th-, and 17th-order components, which have relatively small absolute amplitude values, are excluded from the calculation. When the amplitude value of the first-order frequency component is Va1 and the amplitude value of the n-th-order component is Van, the amplitude ratio Ra is calculated as Ra=|Van / Va1|×100 in units of %.

[0069] As shown in FIG. 12, the amplitude of the third-order component is significantly larger than the amplitude of the first-order component. The amplitude of each frequency component of the differential signal indicates the change in amplitude of each frequency component of the two-unit voltage signal, and shows the same tendency as in Figures 6 and 10 of the first and second embodiments. That is, the amplitude of the third-order component is particularly large, while the amplitudes of the seventh-order and higher-order harmonic components are small. 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 of the first-order component and the amplitude of the third-order component, for example, when the amplitude of the third-order component is clearly greater than the amplitude of the first-order component.

[0070] As described above, in this embodiment, the signal decomposing section 62 decomposes the differential signal between two units of voltage signals acquired at different times into a plurality of frequency components of different orders. The short circuit detection unit 63 then performs short circuit detection based on the result of decomposition of the differential signal by the signal decomposition unit 62. At this time, the short circuit detection unit 63 compares the amplitude of the primary frequency component in the differential signal, which is the amplitude change of the primary frequency component of the two-unit voltage signal, with the amplitude of the low-order harmonic components in the differential signal, which is the amplitude change of the low-order harmonic components, to determine whether the stator core 21 is short circuited.

[0071] Therefore, similarly to the first embodiment, occurrence of a short circuit in the stator core 21 can be detected with high accuracy while the turbine generator 10 is operating in a state where the magnetic flux density in the stator core 21 is relatively high. Furthermore, the signal decomposition unit 62 receives the differential signal of two voltage signals and performs frequency decomposition, so the number of signals to be handled can be reduced by half, thereby reducing the processing load.

[0072] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in this application, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with a component of another embodiment. [Explanation of symbols]

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

Claims

1. a signal acquisition unit that acquires a voltage signal from a magnetic detector that is disposed on the stator side facing the rotor of the rotating electric machine; a signal decomposition unit that decomposes the voltage signal into a plurality of frequency components of different orders; a short-circuit detection unit that determines a short circuit in a laminated stator core based on odd-order low-order harmonic components and a first-order frequency component among the frequency components decomposed by the signal decomposition unit. the signal acquisition unit acquires the voltage signal in units of one electrical angle cycle; the short circuit detection unit detects an amplitude change of the low-order harmonic component and an amplitude change of the primary frequency component based on two units of the voltage signal acquired at different times, and determines a short circuit in the stator core based on a comparison between the amplitude change of the low-order harmonic component and the amplitude change of the primary frequency component. A short circuit detection device for rotating electrical machines.

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

3. the signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into a plurality of frequency components of different orders; the short circuit detection unit compares the amplitude change of the primary frequency component with the amplitude change of the low-order harmonic component based on the results of decomposition of the two units of the voltage signal by the signal decomposition unit. The short circuit detection device for a rotating electrical machine according to claim 1.

4. the signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into a plurality of frequency components of different orders; the short circuit detection unit compares the amplitude change of the primary frequency component with the amplitude change of the low-order harmonic component based on the results of decomposition of the two units of the voltage signal by the signal decomposition unit. The short circuit detection device for a rotating electrical machine according to claim 2.

5. the signal decomposition unit decomposes a differential signal of two units of the voltage signals into a plurality of frequency components of different orders; The short circuit detection unit compares the amplitude of the primary frequency component in the difference signal, which corresponds to the amplitude change of the primary frequency component, with the amplitude of the low-order harmonic component in the difference signal, which corresponds to the amplitude change of the low-order harmonic component, based on the result of decomposition of the difference signal by the signal decomposition unit. The short circuit detection device for a rotating electrical machine according to claim 1.

6. the signal decomposition unit decomposes a differential signal of two units of the voltage signals into a plurality of frequency components of different orders; The short circuit detection unit compares the amplitude of the primary frequency component in the difference signal, which corresponds to the amplitude change of the primary frequency component, with the amplitude of the low-order harmonic component in the difference signal, which corresponds to the amplitude change of the low-order harmonic component, based on the result of decomposition of the difference signal by the signal decomposition unit. The short circuit detection device for a rotating electrical machine according to claim 2.

7. 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; The short-circuit detection device for a rotating electrical machine according to any one of claims 1 to 6.

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

9. The short circuit detection unit calculates and uses an amplitude ratio as the amplitude change. The short circuit detection device for a rotating electrical machine according to claim 7.

10. a signal acquiring step of acquiring a voltage signal from a magnetic detector disposed on a stator side facing a rotor of the rotating electric machine; a signal decomposition step of decomposing the voltage signal into a plurality of frequency components of different orders; a short-circuit detection step of determining a short circuit in a laminated stator core based on odd-order low-order harmonic components and a first-order frequency component among the frequency components resolved in the signal resolution step. the signal acquiring step acquires the voltage signal with one electrical angle cycle as one unit; The short-circuit detection step detects an amplitude change of the low-order harmonic component and an amplitude change of the primary frequency component based on two units of the voltage signal acquired at different times, and determines a short circuit in the stator core based on a comparison between the amplitude change of the low-order harmonic component and the amplitude change of the primary frequency component. A method for detecting a short circuit in a rotating electrical machine.

11. the signal acquiring step repeatedly acquires the voltage signal at different times, with one electrical angle cycle being one unit; The short circuit detection step determines whether the stator core is short-circuited based on two units of the voltage signals, namely, a previously acquired voltage signal and a currently acquired voltage signal. The method for detecting a short circuit in a rotating electrical machine according to claim 10.

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