WO2024089788A1

WO2024089788A1 - Short circuit detection device and short circuit detection method for rotating electric machine

Info

Publication number: WO2024089788A1
Application number: PCT/JP2022/039884
Authority: WO
Inventors: 勇二滝澤
Original assignee: 三菱電機株式会社
Priority date: 2022-10-26
Filing date: 2022-10-26
Publication date: 2024-05-02

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

Apparatus and method for detecting short circuit in rotating electrical machine

This application relates to a device and method for detecting short circuits in rotating electrical machines.

In the stator core of a rotating electric machine using 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 an increase in 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 inside the rotating electric machine is high, and if a short circuit occurs between the laminations of the stator core, the balance of the frequency components of the magnetic flux density changes significantly.

In the conventional technology 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 of this magnetic flux wave. Then, by detecting the even harmonics of the voltage induced in a search coil placed in the gap, a fault in the rotating electric machine is detected.
Furthermore, the conventional technology described in Patent Document 2 describes that when the 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 fluxes in the rotating electric machine. It also describes that an improvement in the stator core structure can be used to suppress the generation of harmonic currents caused by magnetic saturation, thereby reducing the vibration and electromagnetic noise of the rotating electric machine.

Japanese Patent Application Laid-Open No. 53-84101 JP 2010-130839 A

The conventional technology 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 conventional technology described in the above-mentioned Patent Document 2 is intended to mitigate 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 during operation of the rotating electric machine 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 a short circuit cannot be detected with high accuracy.

This application discloses technology to solve the problems described above, and aims to provide a short circuit detection device and method for a rotating electric machine that can accurately detect short circuits that occur between laminations in the stator core while the rotating electric machine is operating with a relatively high magnetic flux density in the stator core.

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 arranged 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 a short circuit in a laminated stator core based on odd-order low-order harmonic components and a primary frequency component among the frequency components decomposed by the signal decomposition unit. The signal acquisition unit acquires the voltage signal with one electrical angle period as one unit. The short circuit detection unit detects the amplitude change of the low-order harmonic components and the 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 components and the amplitude change of the primary frequency component.

The method for detecting a short circuit in a rotating electric machine disclosed in the present application includes a signal acquisition step of acquiring a voltage signal from a magnetic detector arranged 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 primary frequency component among the frequency components decomposed in the signal decomposition step. The signal acquisition step acquires the voltage signal with one electrical angle period as one unit. The short circuit detection step detects the amplitude change of the low-order harmonic components and the 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 components and the amplitude change of the primary frequency component.

The rotating electric machine short circuit detection device and short circuit detection method disclosed in this application can accurately detect short circuits that occur between laminations in the stator core while the rotating electric machine is operating with a relatively high magnetic flux density in the stator core.

1 is a configuration diagram showing a rotating electric machine and a short circuit detection device according to a first embodiment; 4 is a waveform diagram showing a voltage signal acquired by a signal acquiring unit according to the first embodiment in a healthy state. FIG. 4 is a waveform diagram showing a voltage signal acquired by a signal acquiring unit according to the first embodiment during a short circuit. FIG. 5 is a diagram showing a magnetic flux density distribution when the stator core is short-circuited according to the first embodiment. FIG. 4 is a spectral diagram showing the amplitudes of odd-order components, among the frequency components decomposed by the signal decomposition unit according to the first embodiment, in a healthy state and in a short-circuit state. FIG. 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. FIG. 2 is a flowchart illustrating a short circuit detection method according to the first embodiment. 2 is a configuration diagram showing an example of hardware for implementing each function of the signal processing device according to the first embodiment; FIG. 10 is a configuration diagram showing another example of hardware for realizing each function of the signal processing device according to the first embodiment. FIG. 13 is a diagram showing the amount of change in amplitude of each frequency component calculated by the short circuit detection unit according to the second embodiment. FIG. 13 is a diagram showing a differential signal between two different voltage signals acquired by a signal acquiring unit according to embodiment 3. FIG. 13 is a spectral diagram showing the amplitude ratio of each frequency component calculated by the short circuit detection unit according to embodiment 3. FIG.

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 used as the rotating electric machine. Fig. 1 shows a cross section perpendicular to the axial direction of the turbine generator 10.

1, the turbine generator 10 includes a stator 20 serving as an armature and a rotor 30 serving 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 .

The axial direction of the stator core 21 is a direction along the axis of the stator core 21 and is a direction perpendicular to the plane of the paper in Fig. 1. The radial direction of the stator core 21 is a radial direction of a circle centered on the axis of the stator core 21. The circumferential direction of the stator core 21 is a 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.

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.

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 about 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.

The field winding 32 is DC excited by an external power source (not shown). As a result, one of the first magnetic pole 34 and the second magnetic pole 35 becomes a north pole, and the other becomes a south pole. In other words, the turbine generator 10 is a two-pole generator.

A gap 40 is formed between the stator core 21 and the rotor core 31. The multi-phase windings 22 are excited with AC by an external power source (not shown). This generates a rotating magnetic field within the gap 40.

The short circuit detection device 100 detects a short circuit 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 a detection signal 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 disposed facing the rotor 30 inside the stator core 21 including the stator slot 23 adjacent to the gap 40. That is, the search coil 50 is disposed facing the rotor 30 on the side of the stator 20 including the gap 40.

The search coil 50 is linked with main magnetic flux and leakage magnetic flux. The main magnetic flux is the magnetic flux generated in the air gap 40, and the leakage magnetic flux is the magnetic flux leaking out from each rotor slot 33. The magnetic flux that links with the search coil 50 is called the linkage magnetic flux.

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 interlinked magnetic flux in the search coil 50 varies with the rotation of the rotor 30.
In this case, the short circuit detection device 100 includes the search coil 50 as a magnetic detector. However, the search coil 50 may be configured separately from the short circuit detection device 100 .

The signal processing device 60 includes, as functional blocks, a signal acquiring unit 61, a signal dividing unit 62, and a short circuit detecting unit 63.
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 having different orders. The voltage signal acquired by the signal acquisition unit 61 is treated as one unit for 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.

The short circuit detection unit 63 analyzes the amplitude of the odd-order frequency components from 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 period of electrical angle corresponding to the two poles of the first magnetic pole 34 and the second magnetic pole 35, and third-order and higher harmonic components other than this first-order component. The short circuit detection unit 63 determines whether there is a short circuit in the laminated stator core 21 based on the odd-order lower harmonic components and the first-order component.

When 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 of the odd-order frequency components decomposed by the signal decomposition 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.

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 for a voltage signal of one electrical angle cycle acquired before the occurrence of a short circuit in the stator core 21 and a voltage signal of one electrical angle cycle acquired after the occurrence of a short circuit. In other words, when an amplitude change is observed between the two units of voltage signals in the odd-order frequency components obtained by frequency decomposing two units of voltage signals acquired at different points in time, each unit being one electrical angle cycle, a short circuit in the stator core 21 can be detected.

The two-unit voltage signal is acquired by the signal acquisition unit 61 either continuously or intermittently with a time interval between each unit of voltage waveform. When an amplitude change is observed in each odd-order frequency component between the two-unit voltage signal, 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.

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, 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 detects that a short circuit has occurred in the stator core 21.

Furthermore, the short circuit detection unit 63 outputs information regarding the presence or absence of a short circuit in the stator core 21 to the display device 70.

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 .

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.
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.

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 a fastener 83 that penetrates and holds the stator core 21 inside or at the outer periphery of the stator core 21. In this case, the fastener 81A arranged inside the stator core 21 at the same circumferential position as the search coil 50 shown in Fig. 1, and the fasteners 82A arranged at circumferential positions on both sides of the fastener 81A on the outer periphery of the stator core 21, are the fasteners 83 that form a short circuit.

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.

In this example, the signal processing device 60 uses the voltage signal acquired by the signal acquisition unit 61 to estimate that a short circuit has occurred in the stator core 21. This is explained below.

Each voltage waveform shown in FIG. 2 and FIG. 3 is a voltage waveform of 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.

The voltage waveform shown in FIG. 2 is a voltage waveform when no short circuit occurs and the rotor is in a healthy state, with 32 small voltage fluctuations occurring at each rotor slot pitch.
The voltage waveform shown in FIG. 3 is a voltage waveform when a short circuit occurs, and although the amplitude of the harmonic components increases as described below, the waveform as a whole is substantially the same as that shown in FIG.

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. In addition, although there are orders of 21 or more, Fig. 5 shows orders of 19 or less for the sake of explanation.

The primary component is the fundamental wave component equivalent to the main magnetic flux among the magnetic flux generated in the air gap 40, and has the largest amplitude. The third 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 primary component hardly changes, but the amplitudes of the third and fifth order components increase.

As shown in Figure 4, in region A surrounded by

fasteners

81A and 82A, which are short-circuited with stator core 21, the magnetic flux density decreases due to magnetic shielding. In contrast, in region B, which includes region B1 on the radially inner side of region A and region B2 on the opposite side of region A with respect to the axis, the magnetic flux density increases due to the magnetic flux that is shielded and diverted. The magnetic flux density in the center of the magnetically saturated region becomes high, and the magnetic flux density in the peripheral region also becomes high, widening the magnetically saturated region and increasing the harmonic components.

The detouring magnetic flux makes a half-circle detour as in region B, resulting in spatial fluctuations in two or four places on the core back or teeth side, and therefore appears mainly as a change in low-order magnetic flux density, tertiary or quintic, rather than a change in primary or higher order magnetic flux density. The effects of magnetic saturation also appear as harmonic components at frequencies that are multiples of 2 or 4, but the higher the frequency, the smaller the voltage value becomes.

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

The short circuit detection unit 63 calculates the amplitude ratio between the same lower orders among the odd-order harmonic components decomposed by the signal decomposition unit 62 .
FIG. 6 is a diagram showing the amplitude ratios of the respective frequency components 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.

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 units of %, where V1n is the amplitude value of the nth order and V2n is the amplitude value of the other. The area of magnetic saturation increases with 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 higher order frequency components of 7th and above 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 characterized by a large effect of magnetic saturation due to a short circuit and a large amplitude ratio.

In this case, the fifth-order component is excluded, and it can be seen that the amplitude ratio of the third-order component is large. In general, 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 moderate and balanced.

6, the amplitude ratio of the higher frequency components is 0.0 to 1.2%, while the amplitude ratio of the third-order component is about 5%, which is much more 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.
In the short circuit detection unit 63, when the amplitude ratio of the third-order component is clearly 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, the occurrence of a short circuit in the stator core 21 is detected. The determination that the amplitude ratio of the third-order component is clearly larger may be made, for example, when the difference or ratio is larger than a set value.

By making the 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.
In addition, when the stator core 21 is magnetically saturated, the amplitude of the harmonic components is larger than when it is not magnetically saturated, so it is possible to analyze with a good signal-to-noise ratio the amplitude ratio of the harmonic components before and after a short circuit occurs in the stator core 21. 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.

Next, the short circuit detection method according to this embodiment will be described below with reference to the drawings.
7 is a diagram showing a flowchart illustrating the 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.

When the short circuit detection routine is started, first, the signal acquiring unit 61 acquires a voltage signal of one unit (one electrical angle period) from the search coil 50 (step S110).
Next, the signal decomposition 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).

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 detector 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 terminates the current routine (step S150).
If the result is No in step S140, the short circuit detection unit 63 outputs information indicating that "no short circuit has occurred" to the display device 70, and ends the current routine (step S160).

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.

In the signal acquiring step, a voltage signal of one unit (corresponding to one electrical angle period) is acquired from the search coil 50 disposed opposite the rotor 30. In the signal decomposition step, the voltage signal acquired in the signal acquiring step is decomposed into a plurality of frequency components having 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 the voltage signal in the previous routine and the voltage signal in the current routine, which are two units of voltage signals acquired at different times. 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. Also, 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.

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 and the amplitude ratio of the primary frequency component based on two units of voltage signals acquired at different times, to determine a short circuit in the stator core 21. Therefore, the occurrence of a short circuit in the stator core 21 can be accurately detected while the turbine generator 10 is operating in a state in which the magnetic flux density of the stator core 21 is relatively high.
When the turbine generator 10 is operated with a low magnetic flux density in the stator core 21, the accuracy of short circuit detection deteriorates because it is difficult to detect the change in amplitude of the harmonic components before and after a short circuit occurs in the stator core 21. In that 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 flows, and no problematic malfunction occurs.

The short circuit detection step in the above embodiment is to newly detect 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, the contact portion may be burned out by a slight short-circuit current, and the short circuit may be resolved. Since the short circuit detection device 100 detects the occurrence of a short circuit in the stator core 21 by capturing the change in two units of voltage signals acquired at different times, it is not necessarily the case 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 is resolved is the voltage signal of two units.

In addition, 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 the amplitude due to the effects of magnetic saturation, the signal-to-noise ratio of the amplitude ratio is good, and a short circuit can be determined with higher accuracy.

In the above embodiment, the rotor 30 is disposed on the inner circumference side of the stator 20, but the rotor 30 may be disposed on the outer circumference side of the stator 20.

In the above embodiment, the turbine generator 10 is used as the rotating electric machine, but the rotating electric 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.

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 for realizing each function of the signal processing device 60. In this case, the signal processing device 60 is configured by a processing circuit 60A which is dedicated hardware.

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 of these.

FIG. 9 is a configuration diagram showing another example of hardware that realizes each function of the signal processing device 60 according to the first embodiment. In this case, the processing circuit 60B includes a processor 201 and a memory 202.

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.

The program stored in memory 202 can also be said to cause the computer to execute the procedures or methods of each part described above. In other words, this program is a short circuit detection program, and is a program that causes the computer to execute signal acquisition processing, signal decomposition processing, and short circuit detection processing.

Here, 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. Also included in memory 202 are magnetic disks, flexible disks, optical disks, compact disks, mini disks, DVDs, etc.

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

In this way, the processing circuit can realize the functions of the signal processing device 60 described above through hardware, software, firmware, or a combination of these.

Embodiment 2.
In the above-mentioned first embodiment, 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 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.
If 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|.

As shown in Fig. 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. In particular, the amplitude change amount of the third order component is large. Moreover, the amplitude change amount of the seventh or higher order high-order harmonic components is small, showing the same tendency as in Fig. 6 of the above-mentioned embodiment 1 using the amplitude ratio.
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 in the primary component and the amplitude change in the third-order component, for example, when the amplitude change in the third-order component is clearly greater than the amplitude change in the primary component.

As described above, in this embodiment, the amount of change in amplitude of the odd-order low-order harmonic components and the amount of change in amplitude of the primary frequency component are compared based on two units of voltage signals acquired at different times to determine a short circuit in the stator core 21. Therefore, similar to the first embodiment, the occurrence of a short circuit in the stator core 21 can be accurately detected while the turbine generator 10 is operating in a state in which the magnetic flux density of the stator core 21 is relatively high.
In addition, since the amount of change in amplitude is used to determine whether a short circuit exists, the magnitude of the absolute amplitude value does not affect the S/N ratio, and therefore, a short circuit can be detected with high accuracy without removing order components with small absolute amplitude values.

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 the decomposition of two units of the 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.

Fig. 11 is a diagram showing a differential signal between two different voltage signals acquired by the signal acquisition 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 difference signal between the two units of voltage signals into a plurality of 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 difference signal represents the amplitude change when the two units of voltage signals are frequency-decomposed.

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 ratio (%) of the amplitude of each odd-numbered frequency component to the amplitude of the first frequency component is expressed as the amplitude ratio. 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.
If the amplitude value of the first frequency component is Va1 and the amplitude value of the nth frequency component is Van, the amplitude ratio Ra is calculated as Ra=|Van/Va1|×100, in units of %,.

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 difference signal indicates the amplitude change of each frequency component of the two-unit voltage signal, and shows the same tendency as in Figures 6 and 10 of the above-mentioned

embodiments

1 and 2. That is, the amplitude of the third-order component is particularly large, and the amplitudes of the seventh-order and higher 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 primary 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 primary component.

As described above, in this embodiment, the signal decomposition section 62 decomposes the difference 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 detects a short circuit 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.

Therefore, similarly to the first embodiment, the 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 in which the magnetic flux density in the stator core 21 is relatively high.
Furthermore, the signal decomposition unit 62 receives the difference signal between two units of voltage signals and performs frequency decomposition, so the number of signals to be handled can be reduced by half, and the processing load can be reduced.

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 modifications not exemplified are assumed within the scope of the technology disclosed in this application, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment.

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

a signal acquiring unit that acquires a voltage signal from a magnetic detector that is disposed on a stator side facing a rotor of a rotating electric machine;
a signal decomposition unit that decomposes the voltage signal into a plurality of frequency components having different orders;
a short circuit detection unit that determines a short circuit in a laminated stator core based on an odd-order low harmonic component and a first order frequency component among the frequency components decomposed by the signal decomposition unit, the signal acquisition unit acquires the voltage signal with one electrical angle cycle as one unit,
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 signals acquired at different times, and determines a short circuit of 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 rotating electrical machine short circuit detection device.
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.
The signal decomposition unit decomposes the voltage signal acquired by the signal acquisition unit into a plurality of frequency components having different orders,
The short circuit detection unit compares an amplitude change of the first frequency component with an amplitude change of the low-order harmonic component based on a result of decomposition of the two units of the voltage signal by the signal decomposition unit.
The short circuit detection device for a rotating electric machine according to claim 1 or 2.
The signal decomposition unit decomposes a differential signal of two units of the voltage signals into a plurality of frequency components having different orders of frequency,
The short circuit detection unit compares an amplitude of a first frequency component in the difference signal, which corresponds to an amplitude change of the first frequency component, with an amplitude of a low-order harmonic component in the difference signal, which corresponds to an amplitude change of the low-order harmonic component, based on a result of the decomposition of the difference signal by the signal decomposition unit.
The short circuit detection device for a rotating electric machine according to claim 1 or 2.
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 electric machine according to any one of claims 1 to 4.
The short circuit detection unit calculates and uses an amplitude ratio as the amplitude change.
The short circuit detection device for a rotating electric machine according to any one of claims 1 to 5.
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 having different orders;
a short circuit detection step of determining a short circuit in a laminated stator core based on an odd-order low harmonic component and a first order frequency component among the frequency components resolved in the signal resolution step, the signal acquisition step acquiring 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 signals acquired at different times, and determines a short circuit of 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.
the signal acquiring step repeatedly acquires the voltage signal at different times, with one electrical angle period being one unit;
The short circuit detection step determines whether or not the stator core is short-circuited based on two units of the voltage signal, 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 7.