JP7217682B2 - Diagnosis system and method for rotary electric machine - Google Patents

Description

The present invention relates to a diagnostic system and diagnostic method for rotating electric machines such as electric motors, generators, and induction machines.

Sudden failure of rotary electric machines such as electric motors, generators, and induction machines can bring about an unexpected stoppage of operation of the user's entire system, resulting in great loss to social life. For example, if a rotating electrical machine stops unexpectedly at various production plants, all the products being manufactured may be lost, delaying the delivery to the supplier. Sudden stoppage of generators in power plants can also cause large economic losses. It is reported that bearings account for 35% of the failures of rotating electric machines, and that insulation accounts for 35%. Preventing these failures before they occur greatly contributes to the stable operation of rotating electric machines. do.

In recent years, due to technological innovations in materials and device structures, electrical equipment including rotating electric machines has come to be designed in a well-balanced manner with respect to trade-offs such as equipment reliability and manufacturability. However, there have been occasional cases of electrical equipment failing under harsh ambient environments and operating conditions, making it increasingly important to use inexpensive and highly accurate diagnostic technology.

As an example of a conventional diagnostic system for a rotating electric machine, Patent Document 1 discloses that the zero-phase current of a three-phase power supply line is measured, and based on the harmonic components extracted from the measured zero-phase current, the power supply line of each phase is detected. An insulation deterioration diagnosis device for deriving an insulation resistance value is described. Further, in Patent Document 2, by using a current sensor attached to each lead wire of each phase of a rotating electric machine and a current sensor attached collectively to the lead wires of all phases, the zero-phase current and a deterioration diagnosis system for diagnosing deterioration of the bearing and deterioration of the insulation of the stator winding by measuring the leakage current flowing through the insulation material of the stator winding.

JP 2013-130440 A JP 2015-215275 A

A rotating electrical machine includes a stator and a rotor, and coils are accommodated in slots provided in cores of the stator and rotor. The surface of the coil arranged in the slot is covered with an insulating layer. A magnetic wedge is placed at the opening of the slot to prevent the coil from falling out of the slot.

A major cause of accidents in rotating electric machines is damage to coils due to magnetic wedges coming off or becoming loose with respect to slots. If the magnetic wedge falls out of the slot or loosens from the slot, the magnetic wedge or fragments of the magnetic wedge break the insulating layer covering the coil arranged in the slot, causing dielectric breakdown and abnormalities in the rotating electrical machine. obtain.

Conventional diagnostic systems, such as those described in US Pat. For this reason, conventionally, the magnetic wedges have been visually detected to be loose from the slots or loose from the slots. There is a problem that dielectric breakdown may occur in Therefore, there is a demand for a diagnostic system capable of detecting abnormalities in the rotating electric machine, such as the magnetic wedge coming off the slot or loosening from the slot.

The present invention aims to provide a diagnostic system and diagnostic method for a rotating electrical machine that can detect an abnormality in the rotating electrical machine by detecting a magnetic wedge falling out of a slot of a core of a stator or rotor or loosening from the slot. aim.

A diagnostic system for a rotating electrical machine according to the present invention includes: a current sensor installed in a reciprocating cable connected to a coil of the rotating electrical machine; measuring a reciprocating current flowing through the reciprocating cable; and inputting the reciprocating current measured by the current sensor. and a diagnostic device for obtaining, from the reciprocating current, leakage current, which is the difference between the current flowing into the coil and the current flowing out of the coil. The diagnosis device obtains a spectrum of the frequency domain of the leakage current from the waveform of the leakage current, and if the obtained spectrum is different from the spectrum of the frequency domain of the leakage current when the rotating electrical machine is normal, It is determined that the rotating electric machine is abnormal.

A method for diagnosing a rotating electrical machine according to the present invention comprises a measuring step of measuring a reciprocating current flowing in a reciprocating cable with a current sensor installed in a reciprocating cable connected to a coil of the rotating electrical machine; a leakage current obtaining step of obtaining a leakage current that is a difference between the current flowing in and the current flowing out of the coil; obtaining a spectrum of the leakage current in the frequency domain from the waveform of the leakage current; a diagnosis step of determining that the rotating electric machine is abnormal if the spectrum of the frequency domain of the leakage current is different from a normal spectrum of the leakage current.

According to the present invention, there is provided a diagnostic system and diagnostic method for a rotating electrical machine capable of detecting an abnormality in the rotating electrical machine by detecting the magnetic wedge falling off from the slot of the core of the stator or rotor or the looseness with respect to the slot. can be done.

The figure which shows the structure of the diagnostic system by Example 1 of this invention. FIG. 4 is a diagram showing an example of a change in ground leakage current over time; FIG. 4 is a diagram showing an example of a frequency domain spectrum of a ground leakage current when the magnetic wedge is normal; FIG. 4 is a diagram showing an example of a frequency-domain spectrum of a ground leakage current when the magnetic wedge is abnormal; FIG. 3 is a diagram showing time zones for performing frequency analysis in the example of the time change of the ground leakage current shown in FIG. 2 in the second embodiment of the present invention; The figure which shows the structure of the diagnostic system by Example 3 of this invention. 1 is a block diagram showing a diagnostic system according to a first embodiment of the present invention and a rotating electrical machine diagnosed by the diagnostic system; FIG. The figure which shows a part of stator of a rotary electric machine. The figure which shows the current sensor installed in the reciprocating cable in which the feeder cable which consists of multiple cables is comprised as a pair.

In a rotating electrical machine, when magnetic wedges installed in slots provided in cores of a stator and a rotor come off from the slots or become loose with respect to the slots, the magnetic field leaking from the rotating electrical machine is distorted. Therefore, by detecting the deformation of the magnetic field leaking from the rotary electric machine, it is possible to detect falling-off and loosening of the magnetic wedges, which account for a large proportion of insulation failure factors. The distortion of the magnetic field leaking from the rotating electric machine appears in the harmonic component of the current that leaks only from the coils arranged in the slots to the insulating layer covering the surface of the coil (hereinafter referred to as "ground leakage current").

In the present invention, a single current sensor measures a reciprocating current flowing in a reciprocating cable connected to each phase of a coil of a rotating electric machine, and a difference between the reciprocating currents is obtained to measure a ground leakage current. A reciprocating cable is a pair of cables through which a current flowing into a coil of a rotating electrical machine and a current flowing out of a coil flow. The difference between the reciprocating currents is the difference between the current flowing into the coil and the current flowing out of the coil (the difference between the current flowing in one side of the reciprocating cable and the current flowing in the other side). The ground leakage current is obtained from the reciprocating current measured by the current sensor as the difference between the reciprocating currents.

In the present invention, by performing frequency analysis on the measured ground leakage current, the magnetic wedge is efficiently and accurately detected as falling out of the slot of the core or loosening with respect to the slot.

According to the present invention, it is possible to detect abnormalities in the rotating electrical machine, such as the magnetic wedge falling out of the slot or loosening from the slot, thereby preventing damage to the coil and dielectric breakdown of the rotating electrical machine caused by these. As a result, it is possible to provide a new diagnostic method that enables maintenance savings, and to improve the efficiency of diagnostic services for rotating electric machines. In addition to distortion of the magnetic field leaking from the rotating electrical machine, changes in the capacitance component of the rotating electrical machine can also be detected as quantities correlated with the insulation characteristics of the rotating electrical machine.

The diagnostic system and diagnostic method for a rotating electric machine according to the present invention can diagnose rotating electric machines such as electric motors, generators, and induction machines. In particular, it is effective for rotating electrical machines with varying loads, such as those used in gas turbines, railroads, automobiles, aircraft, and wind power generators.

Hereinafter, a diagnostic system and a diagnostic method for a rotating electric machine according to embodiments of the present invention will be described with reference to the drawings. Although an example of diagnosing a stator of a rotating electrical machine will be described below, the diagnostic system and diagnostic method for a rotating electrical machine according to the present invention can diagnose a rotor in the same manner as the stator. In the drawings used in this specification, the same or corresponding components are denoted by the same reference numerals, and repeated description of these components may be omitted.

A diagnosing system and a diagnosing method for a rotating electrical machine according to a first embodiment of the present invention will be described.

FIG. 7 is a block diagram showing the diagnosing system 10 according to the first embodiment of the present invention and the rotating electric machine 1 diagnosed by the diagnosing system 10. As shown in FIG. The rotating electric machine 1 is connected to a power system 9 . A diagnostic system 10 is connectable to a reciprocating cable 5 that connects to the rotating electrical machine 1 . In addition, the rotary electric machine 1 is connected to a device 50 that serves as a load.

FIG. 8 is a diagram showing part of the stator 30 of the rotary electric machine 1. As shown in FIG. The stator 30 faces the rotor 40 across an air gap, and includes a stator core 31 and stator coils 32 . A slot 33 is provided in the stator core 31 . The stator coil 32 is housed in the slot 33 and covered with an insulating layer 34 on its surface. A magnetic wedge 35 is installed in the opening of the slot 33 . If the magnetic wedge 35 falls out of the slot 33 or becomes loose with respect to the slot 33, the magnetic wedge 35 and fragments of the magnetic wedge 35 destroy the insulating layer 34 covering the stator coil 32, causing the stator coil 32 to break or become loose. An abnormality of the rotary electric machine 1, namely dielectric breakdown of the rotary electric machine 1, may occur.

FIG. 1 is a diagram showing the configuration of a diagnostic system 10 according to this embodiment, and shows an overall circuit including the diagnostic system 10, a rotating electric machine 1, and a power system 9. As shown in FIG. In this embodiment, the rotating electric machine 1 has three phases of the stator coil 32 connected in a delta connection. The rotating electric machine 1 is also connected to a power system 9 with a power supply cable 3 . The power supply cable 3 is branched at the terminal block 4 of the terminal box and connected to the rotary electric machine 1 as a reciprocating cable 5 . The reciprocating cable 5 is composed of a pair of power supply cables 3 and is connected for each phase of the stator coil 32 of the rotary electric machine 1 .

A diagnostic system 10 includes a current sensor 2 , a measuring device 8 and a diagnostic device 20 . Note that the measuring device 8 and the diagnostic device 20 may be configured by one device (for example, a computer) or may be configured by a plurality of devices.

The current sensor 2 is installed for each phase on the reciprocating cable 5 connected to each phase of the stator coil 32 of the rotating electrical machine 1 and positioned between the terminal block 4 and the rotating electrical machine 1 . One current sensor 2 is provided for each phase of the stator coil 32 of the rotary electric machine 1, and a total of three current sensors 2 are provided. One current sensor 2 is installed on a pair of power supply cables 3 that constitute the reciprocating cable 5, and measures the reciprocating current flowing through the reciprocating cable 5 (the current flowing into the stator coil 32 and the current flowing out of the stator coil 32). do.

The measuring device 8 is connected to the current sensor 2 and has at least one of a communication device and a storage medium. The communication device transmits the reciprocating current measured by the current sensor 2 to the diagnostic device 20 by wireless communication or wired communication. The storage medium stores the reciprocating current measured by the current sensor 2 . The storage medium may be removable from the measuring device 8 . Moreover, the measuring device 8 may be detachable from the diagnostic device 20 . The measuring device 8 can be composed of, for example, a personal computer with a hard disk and a data logger, or an oscilloscope with a storage device and USB connection.

The diagnostic device 20 inputs the reciprocating current measured by the current sensor 2 from the measuring device 8 . The diagnostic device 20 receives the reciprocating current transmitted from the communication device of the measuring device 8, or receives the reciprocating current from the measuring device 8 by being connected to the storage medium of the measuring device 8 storing the reciprocating current. . The diagnostic device 20 obtains a ground leakage current (a current leaking from the stator coil 32 only to the insulating layer 34 covering the surface of the stator coil 32) from the input reciprocating current.

In the diagnostic system 10 according to this embodiment, the current sensor 2 is installed in the reciprocating cable 5 connected to each phase of the stator coil 32 of the rotating electrical machine 1, and the reciprocating current flowing through each phase of the stator coil 32 of the rotating electrical machine 1 is The ground leakage current in each phase of the stator coil 32 of the rotary electric machine 1 is measured with high accuracy by measuring with two current sensors 2 and obtaining the difference between the reciprocating currents with the diagnosis device 20 . The ground leakage current I is a current that leaks from the stator coil 32 only to the insulating layer 34 covering the surface of the stator coil 32. It can be obtained by subtracting the value of the current I2 flowing out from the child coil 32 and finding the difference between the reciprocating currents (I=I1-I2).

FIG. 2 is a diagram showing an example of a change in the ground leakage current over time, and is a diagram created based on experimental results of measuring the ground leakage current. The horizontal axis in FIG. 2 indicates time, and the vertical axis indicates the magnitude (amplitude) of the ground leakage current.

As shown in FIG. 2, the temporal change in the ground leakage current includes a time zone in which the ground leakage current takes a substantially constant value and a time zone in which the ground leakage current increases. That is, the ground leakage current fluctuates and increases intermittently. The ground leakage current takes a substantially constant and stable value in a low output region where the output of the rotary electric machine 1 is small. This constant value is the minimum ground leakage current. An increase in ground leakage current occurs when the load of the rotating electrical machine 1 fluctuates and the output of the rotating electrical machine 1 transitions from a low output region to a high output region and increases.

As shown in FIG. 2, a stable ground leakage current value (amplitude value) appearing in the low output region of the rotary electric machine 1 is referred to as a reference value 12, and an increase in the ground leakage current with respect to the reference value 12 is a variation value 11. called. The reference value 12 can be the minimum value of the ground leakage current.

The diagnostic device 20 performs frequency analysis on the obtained ground leakage current for an arbitrary time period, and detects the magnetic wedge 35 falling off from the slot 33 of the stator core 31 or looseness with respect to the slot 33 . The diagnostic device 20 converts the waveform of the ground leakage current into a spectrum of the frequency domain to obtain the spectrum of the frequency domain of the ground leakage current.

FIG. 3 shows the frequency domain of the ground leakage current when the magnetic wedge 35 is normal, that is, when the magnetic wedge 35 does not drop out of the slot 33 of the stator core 31 or loosen with respect to the slot 33. It is a figure which shows the example of a spectrum, and is the figure created based on the experimental result which measured the ground leakage current. The horizontal axis of FIG. 3 indicates frequency, and the vertical axis indicates ground leakage current (logarithmic value). The rotating electrical machine 1 in which the magnetic wedges 35 are normal is, for example, a rotating electrical machine that has been manufactured and has not started operating, or a rotating electrical machine that has been repaired and has not started operating.

As shown in FIG. 3, in the rotary electric machine 1 with the normal magnetic wedge 35, the peak 21 of the fundamental wave component is detected as the largest peak in the frequency domain spectrum of the ground leakage current, and the next largest peak is the slot harmonic component. A peak 22 due to waves (harmonics due to the presence of slots 33) is detected.

FIG. 4 shows the spectrum of the frequency domain of the ground leakage current when the magnetic wedge 35 is abnormal, that is, when the magnetic wedge 35 falls out of or loosens from the slot 33 of the stator core 31. It is a figure which shows an example, and is a figure created based on the experimental result which measured the ground leakage current. The horizontal axis of FIG. 4 indicates frequency, and the vertical axis indicates ground leakage current (logarithmic value).

As shown in FIG. 4 , in the rotating electrical machine 1 with the abnormal magnetic wedge 35 , the spectrum of the ground leakage current in the frequency domain shows a peak 21 due to the fundamental wave component and a peak 22 due to the slot harmonic, and the magnetic wedge 35 is normal. A peak 23 indicating an abnormality, which does not exist in the spectrum of the rotating electric machine 1, is detected. The peak 23 indicating this anomaly is caused by distortion of the magnetic field leaking from the rotating electric machine 1 due to falling off or loosening of the magnetic wedge 35 . This peak 23 tends to be smaller in amplitude than the peak 22 due to the slot harmonics at the initial stage of the abnormal state of the magnetic wedge 35 . However, in the rotating electrical machine 1 with the abnormal magnetic wedge 35, a peak 23 that does not exist in the rotating electrical machine 1 with the normal magnetic wedge 35 clearly appears.

Therefore, if the frequency domain spectrum of the ground leakage current differs from the frequency domain spectrum of the ground leakage current when the rotating electrical machine 1 is normal, that is, when the magnetic wedge 35 is normal, the magnetic wedge 35 is abnormal. can be determined. Specifically, if a peak that does not exist in the spectrum when the magnetic wedge 35 is normal (however, the peak is higher than the noise level) is detected in the frequency domain spectrum of the ground leakage current, the magnetic wedge 35 is abnormal. can be determined.

The diagnostic device 20 stores the frequency-domain spectrum of the ground leakage current for a normal rotating electric machine 1 (that is, a rotating electric machine 1 with a normal magnetic wedge 35). Then, the diagnosis device 20 compares the obtained spectrum of the frequency domain of the ground leakage current with the spectrum of the frequency domain of the ground leakage current of the normal rotating electric machine 1, and compares the obtained spectrum of the frequency domain of the ground leakage current. If a peak that does not exist in the frequency domain spectrum of the ground leakage current for a normal rotating electrical machine 1 is detected, the rotating electrical machine 1 is abnormal. It is judged to be abnormal because it is loose with respect to the slot 33.

The current sensor 2 can also be installed in the reciprocating cable 5 connected to each phase of the stator coil 32 of the rotary electric machine 1 as follows.

A reciprocating cable 5 connected to one phase of the stator coil 32 of the rotary electric machine 1 is composed of a pair of power supply cables 3 . Each of the pair of power supply cables 3 constituting the reciprocating cable 5 can be composed of a plurality of cables. That is, the reciprocating cable 5 may be configured by a pair of power supply cables 3 each having a plurality of cables.

FIG. 9 is a view showing the current sensor 2 installed on the reciprocating cable 5, which is composed of a pair of power supply cables 3 made up of a plurality of cables. FIG. 9 shows, as an example, a reciprocating cable 5 in which one of a pair of power supply cables 3 is composed of two cables 3a and 3b and the other is composed of two cables 3c and 3d. . The power supply cable 3 can also be composed of three or more cables.

When the reciprocating cable 5 is composed of a pair of power supply cables 3 made up of a plurality of cables, that is, the power supply cable 3 made up of cables 3a and 3b and the power supply cable 3 made up of cables 3c and 3d, the current sensor 2 can be installed in a part of cables 3 a, 3 b, 3 c, and 3 d constituting the power supply cable 3 . FIG. 9 shows, as an example, a configuration in which the current sensors 2 are installed on the cable 3b of one power supply cable 3 and the cable 3c of the other power supply cable 3. As shown in FIG.

In this way, by installing the current sensor 2 on a part of the plurality of cables, even if the reciprocating cable 5 is thick, the current sensor can be detected according to the sizes of the reciprocating cable 5 and the current sensor 2. 2 can be installed.

In the diagnostic system 10 according to the present embodiment, by performing frequency analysis on the measured ground leakage current, an abnormality of the magnetic wedge 35, that is, the magnetic wedge 35 falling off from the slot 33 of the stator core 31 or the slot 33 can be detected efficiently and accurately, abnormalities in the rotating electrical machine 1 can be detected, and damage to the stator coil 32 and dielectric breakdown of the rotating electrical machine 1 can be prevented.

A diagnosing system and a diagnosing method for a rotating electric machine according to a second embodiment of the present invention will be described. In the following, this embodiment will be described mainly with respect to the differences from the first embodiment.

The inventors have found that the ground leakage current fluctuates in a rotating electric machine having load fluctuations, as described with reference to FIG. 2 in the first embodiment. When the ground leakage current fluctuates, the harmonic components of the ground leakage current include components caused by mechanical vibrations. Therefore, in the frequency domain spectrum of the ground leakage current, a peak due to the distortion of the magnetic field leaking from the rotating electrical machine appears. It is difficult to detect only

Therefore, in the present embodiment, the diagnosis device 20 removes factors other than the abnormality of the magnetic wedge 35 that affect the spectrum of the ground leakage current in the frequency domain. Frequency analysis is performed for the time period that is the value of .

FIG. 5 is a diagram showing time zones for performing frequency analysis in the example of the time change of the ground leakage current shown in FIG. The diagnostic device 20 extracts a time period 13 in which the obtained magnitude of the ground leakage current does not include the fluctuation value 11 and is within a predetermined range. This range of the magnitude of the ground leakage current includes a reference value of 12, and the upper and lower limits can be arbitrarily determined so that the ground leakage current can be regarded as approximately the reference value of 12. If the magnitude of the ground leakage current is within this range, the diagnosis device 20 determines that the ground leakage current is a substantially constant value (reference value 12).

Then, the diagnostic device 20 performs frequency analysis of the ground leakage current only for the extracted time period 13, and converts the waveform of the ground leakage current into a spectrum in the frequency domain. That is, the diagnosis device 20 performs the frequency analysis of the ground leakage current only during the time period 13 when the ground leakage current is substantially at the reference value 12, has a small variation, and has a high SN ratio.

In this embodiment, frequency analysis is performed on the ground leakage current that does not include fluctuations caused by mechanical vibration (for example, vibration due to mechanical deterioration). The peak 23 (the peak caused by deformation of the magnetic field leaking from the rotary electric machine 1 due to the detachment or loosening of the magnetic wedge 35) can be detected with high accuracy, and the abnormality of the magnetic wedge 35 can be detected with higher accuracy and sensitivity. .

In the diagnostic system 10 according to the present embodiment, the frequency analysis is performed in the time period 13 in which the ground leakage current does not include the fluctuation value 11 and has a substantially constant value, so that the abnormality of the magnetic wedge 35 can be detected with higher accuracy and sensitivity. It is possible to detect an abnormality in the rotating electrical machine 1 and prevent damage to the stator coil 32 and dielectric breakdown of the rotating electrical machine 1 .

A diagnosing system and a diagnosing method for a rotating electric machine according to a third embodiment of the present invention will be described. In the following, this embodiment will be described mainly with respect to the differences from the first embodiment.

FIG. 6 is a diagram showing the configuration of the diagnostic system 10 according to this embodiment, and shows the entire circuit including the diagnostic system 10, the rotating electric machine 1, and the electric power system 9, as in FIG.

In the diagnostic system 10 according to this embodiment, the measuring device 8 includes at least one of the wireless communication device 7 and the mass storage 6 .

When the measuring device 8 includes the wireless communication device 7, the measuring device 8 transmits measurement data such as the reciprocating current measured by the current sensor 2 to the data center by wireless communication using the wireless communication device 7, and stores the data in the data center. . The measuring device 8 having the wireless communication device 7 can also transmit the ground leakage current obtained by the diagnostic device 20 to the data center by wireless communication.

If the measuring device 8 is equipped with the mass storage 6 , the measuring device 8 stores measurement data in the mass storage 6 . The measuring device 8 having the large-capacity storage 6 can also store the ground leakage current obtained by the diagnostic device 20 in the large-capacity storage 6 .

In the diagnostic system 10 according to this embodiment, since the round-trip current and the ground leakage current can be continuously measured while the round-trip cable 5 is live, the amount of data to be accumulated is enormous. For this reason, in the case of continuous measurement over a long period of time, it is effective to transfer data using the wireless communication device 7 or save the data in the large-capacity storage 6 .

When data is transferred to the data center by the wireless communication device 7, problems may occur in data transfer. Also, if data is continuously stored in the large-capacity storage 6 for a long period of time, problems may arise in data storage. For this reason, the diagnostic system 10 according to the present embodiment preferably uses the wireless communication device 7 and the large-capacity storage 6 separately or both in combination depending on the situation.

A diagnostic system and diagnostic method for a rotating electric machine according to a fourth embodiment of the present invention will be described. As described with reference to FIG. 7 in the first embodiment, the rotating electrical machine 1 diagnosed by the diagnostic system 10 is connected to the device 50 that serves as a load. In this embodiment, an example of a rotating electric machine 1 that can be diagnosed by the diagnostic system 10 and that is connected to a device 50 in which load fluctuations occur and whose load current fluctuates will be described.

Examples of the rotating electric machine 1 diagnosed by the diagnostic system 10 according to this embodiment include motors for automobiles, generators for gas turbines, generators for wind power, rotating electric machines for vehicles, motors for aircraft, and the like. In addition to these, the diagnostic system 10 can diagnose the rotating electric machine 1 in general, in which the amount of power generation and the output of the motor fluctuate.

The diagnostic system 10 according to the present embodiment can diagnose the above-described rotating electrical machine 1 and the like, detect an abnormality in the magnetic wedge 35 efficiently and with high accuracy, detect an abnormality in the rotating electrical machine 1, and detect an abnormality in the stator coil 32. damage and dielectric breakdown of the rotary electric machine 1 can be prevented.

A diagnosing system and a diagnosing method for a rotating electric machine according to a fifth embodiment of the present invention will be described. The diagnostic system 10 according to the present embodiment can detect the presence or absence of heat deterioration, moisture absorption deterioration, and the like of the insulating layer 34 of the stator coil 32 in the rotating electric machine 1 .

In the diagnostic system 10 according to this embodiment, the capacitance component of the stator coil 32 of the rotary electric machine 1 can be obtained with high accuracy from the ground leakage current. Since the ground leakage current is proportional to the capacitance of the stator coil 32, the diagnostic device 20 can determine the capacitance of the stator coil 32 from the ground leakage current. Therefore, the diagnostic device 20 can determine the change in the capacitance of the stator coil 32 from the change in the ground leakage current, and if the capacitance of the stator coil 32 decreases, the insulation layer 34 of the stator coil 32 heats up. and deterioration due to moisture absorption can be detected.

Such detection of thermal deterioration, moisture absorption deterioration, etc. is particularly effective for the rotary electric machine 1 with a rated voltage of 2 kV or less, in which partial discharge deterioration does not occur.

The diagnostic system 10 according to the present embodiment can efficiently and accurately detect abnormalities in the magnetic wedges 35 and thermal deterioration and hygroscopic deterioration of the stator coils 32, especially for the rotating electrical machine 1 with a rated voltage of 2 kV or less. Abnormality of the rotating electrical machine 1 can be detected, and damage to the stator coil 32 and dielectric breakdown of the rotating electrical machine 1 can be prevented.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible. For example, the above embodiments have been described in detail in order to facilitate understanding of the present invention, and the present invention is not necessarily limited to aspects having all the described configurations. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to delete a part of the configuration of each embodiment, or to add or replace another configuration.

DESCRIPTION OF SYMBOLS 1... Rotary electric machine, 2... Current sensor, 3... Power supply cable, 3a, 3b, 3c, 3d... Cable which comprises a power supply cable, 4... Terminal block, 5... Reciprocating cable, 6... Large capacity storage, 7... Wireless communication Equipment 8 Measuring device 9 Power system 10 Diagnosis system 11 Fluctuation value 12 Reference value 13 Time period for frequency analysis of ground leakage current in Example 2 20 Diagnosis device 21 22 Peak due to slot harmonic 23 Peak indicating abnormality 30 Stator 31 Stator core 32 Stator coil 33 Slot 34 Insulating layer 35 Magnetic wedge 40 Rotor 50 Load device.

Claims (7)

a current sensor installed in a reciprocating cable connected to a coil of a rotating electric machine and measuring a reciprocating current flowing through the reciprocating cable;
a diagnostic device that inputs the reciprocating current measured by the current sensor and obtains a leakage current, which is the difference between the current flowing into the coil and the current flowing out of the coil, from the reciprocating current;
with
The diagnostic device obtains a spectrum of the frequency domain of the leakage current from the waveform of the leakage current only for a time period in which the magnitude of the leakage current is within a predetermined range, and the obtained spectrum is the determining that the rotating electrical machine is abnormal if the spectrum of the frequency domain of the leakage current is different from when the rotating electrical machine is normal;
A diagnostic system for a rotating electrical machine, characterized by: When the diagnostic device detects, in the obtained spectrum, a peak that does not exist in the spectrum in the frequency domain of the leakage current when the rotating electrical machine is normal, it determines that the rotating electrical machine is abnormal.
A diagnostic system for a rotary electric machine according to claim 1 . The reciprocating cable is composed of a pair of power supply cables, the power supply cable is composed of a plurality of cables,
wherein the current sensor is installed in a part of the plurality of cables constituting the power supply cable,
A diagnostic system for a rotary electric machine according to claim 1 . The current sensor is installed on the reciprocating cable connected to the coil of the rotating electric machine whose load fluctuates.
A diagnostic system for a rotary electric machine according to claim 1 . The current sensor is installed on the reciprocating cable connected to the coil of the rotating electrical machine with a rated voltage of 2 kV or less,
A diagnostic system for a rotary electric machine according to claim 1 . a measurement step of measuring a reciprocating current flowing in the reciprocating cable with a current sensor installed in the reciprocating cable connected to the coil of the rotary electric machine;
a leakage current acquisition step of obtaining a leakage current, which is the difference between the current flowing into the coil and the current flowing out of the coil, from the reciprocating current;
A spectrum of the frequency domain of the leakage current is obtained from the waveform of the leakage current only for a time period in which the magnitude of the leakage current is within a predetermined range, and the obtained spectrum indicates that the rotating electrical machine is normal. a diagnosing step of determining that the rotating electric machine is abnormal if the spectrum of the frequency domain of the leakage current differs from the spectrum of the leakage current in the case;
A method for diagnosing a rotating electric machine, comprising: In the diagnosis step, when a peak that does not exist in the spectrum in the frequency domain of the leakage current when the rotating electrical machine is normal is detected in the obtained spectrum, the rotating electrical machine is determined to be abnormal.
The method for diagnosing a rotating electric machine according to claim 6 .

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