Diagnostic device, diagnostic system provided with same, and diagnostic method

Abstract

A control unit (14) controls a switching device (2) that is electrically connected to a power supply path from a power supply (5) to a load (6). A signal converting unit (72, 73) calculates an intensity signal indicating a time variation of a spectral intensity by means of time-frequency conversion for each time width, with respect to an original signal indicating a time variation of an electrical appliance that is electrically connected to the load (6), and generates a converted signal by summing the intensity signals with respect to time or frequency. A feature extracting unit (74) extracts a feature from the converted signal. A diagnosing unit (76) diagnoses the electrical appliance on the basis of the feature. The control unit (14) causes the switching device (2) to perform an opening operation and a closing operation while continuing to supply power to the load (6). The signal conversion unit (72, 73) generates the converted signal on the basis of the original signal emitted from the electrical appliance in association with the control of the switching device (2) by the control unit (14).

Description

Diagnostic device, diagnostic system including the same, and diagnostic method

[0001] The present disclosure relates to a diagnostic device, a diagnostic system including the same, and a diagnostic method.

[0002] Japanese Patent Laid-Open Publication No. 2019-145348 (Patent Document 1) discloses a method for diagnosing operational abnormalities in a power switch. This method involves placing measurement microphones around the power switch and measuring the operating sound generated when the power switch is opened and closed using the measurement microphones. The method then creates a map showing the relationship between frequency and time using a fast Fourier transform based on a graph showing the relationship between the measured sound pressure and time, and determines whether the power switch is operating abnormally based on the number or positions of peaks that appear in the map.

[0003] Japanese Patent Application Laid-Open No. 2019-145348

[0004] In a system configuration in which a switchgear (and other electrical equipment) is electrically connected to a power supply path from a power source to a load, it is possible to diagnose the electrical equipment based on signals generated in response to contact opening and closing operations of the switchgear. Conventionally, diagnosing electrical equipment required stopping the power supply from the power source to the load, which limited the timing at which the diagnosis of the electrical equipment could be performed. It is desirable to have more opportunities to diagnose electrical equipment so that the electrical equipment can be diagnosed at desired times or more frequently.

[0005] The present disclosure has been made to solve the above-mentioned problems, and one of the objects of the present disclosure is to increase the opportunities for diagnosing electrical equipment.

[0006] A diagnostic device according to an aspect of the present disclosure includes a control unit, a signal conversion unit, a feature extraction unit, and a diagnosis unit. The control unit controls a switchgear electrically connected to a power supply path from a power source to a load. The signal conversion unit calculates an intensity signal indicating a time change in spectral intensity by performing a time-frequency transformation for each time width on an original signal indicating a time change in an electric device electrically connected to the load, and generates a converted signal by summing the intensity signals over time or frequency. The feature extraction unit extracts features from the converted signal. The diagnosis unit diagnoses the electric device based on the features. The control unit causes the switchgear to perform an opening operation and a closing operation while continuing to supply power to the load. The signal conversion unit generates the converted signal based on the original signal emitted from the electric device in response to control of the switchgear by the control unit.

[0007] A diagnostic method according to an aspect of the present disclosure includes first to fourth steps. The first step is a step of controlling a switchgear electrically connected to a power supply path from a power source to a load. The second step is a step of calculating an intensity signal indicating a time change in spectral intensity by performing a time-frequency transformation for each time width on an original signal indicating a time change of an electric device electrically connected to the load, and generating a converted signal by summing the intensity signals with respect to time or frequency. The third step is a step of extracting a feature from the converted signal. The fourth step is a step of diagnosing the electric device based on the feature. The generating step includes a step of performing a contact opening operation and a contact closing operation on the switchgear while continuing to supply power to the load, and generating the converted signal based on an original signal emitted from the electric device in response to the contact opening operation and the contact closing operation.

[0008] According to the present disclosure, it is possible to increase opportunities for diagnosing electrical equipment.

[0009] FIG. 1 is a diagram showing an overall configuration of a diagnostic system according to an embodiment. FIG. 2 is a diagram showing a configuration of a switching gear diagnostic system according to embodiment 1. FIG. 3 is a functional block diagram for explaining an overview of the function of a signal processing unit. FIG. 4 is a conceptual diagram for explaining signal processing by the signal processing unit. FIG. 5 is a diagram showing an example of an actual waveform. FIG. 6 is a diagram showing a first example of a change detected in a spectral flux signal. FIG. 7 is a diagram showing a second example of a change detected in a spectral flux signal. FIG. 8 is a diagram for explaining a first example of a feature quantity. FIG. 9 is a diagram for explaining a second example of a feature quantity. FIG. 10 is a diagram for explaining a third example of a feature quantity. FIG. 11 is a diagram for explaining a fourth example of a feature quantity. FIG. 12 is a flowchart showing a first example of a processing procedure of processing performed in embodiment 1. FIG. 13 is a flowchart showing an example of a processing procedure of signal conversion. FIG. 14 is a flowchart showing an example of a processing procedure of feature quantity extraction. FIG. 15 is a flowchart showing an example of a processing procedure of abnormality diagnosis. FIG. 16 is a flowchart showing a second example of a processing procedure of processing performed in embodiment 1. FIG. 17 is a diagram showing a configuration of a switching gear diagnostic system according to embodiment 2. FIG. 18 is a flowchart showing a first example of a processing procedure of processing performed in embodiment 1. FIG. 19 is a flowchart showing a second example of a processing procedure of processing performed in embodiment 2. FIG. 19 is a diagram showing a configuration of a switching gear diagnostic system according to embodiment 3. FIG. 19 is a flowchart showing an example of a processing procedure of processing performed in embodiment 3. 13 is a flowchart showing an example of a processing procedure of processing executed in the fourth embodiment.

[0010] Hereinafter, the present embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0011] 1 is a diagram showing the overall configuration of a diagnostic system according to the present embodiment. The diagnostic system 100 includes a diagnostic device 1, an opening / closing device 2, and a sensor 3.

[0012] The switchgear 2 is an electrical device to be diagnosed in this embodiment. The switchgear 2 is housed inside a power receiving and distribution facility (switchgear). However, the switchgear 2 is not limited to a switchgear. The diagnostic target may be other types of electrical devices connected to a power supply path from a power source to a load, as will be described later. The diagnostic target may be, for example, a voltage transformer (VT), a current transformer (CT), or a fan.

[0013] The sensor 3 detects the state of the switching device 2 (typically, a change in the state of the switching device 2 due to a failure, abnormality, defect, etc. of the switching device 2). The sensor 3 may be a contact sensor arranged to be in contact with the switching device 2, or a non-contact sensor arranged not to be in contact with the switching device 2 (but in the vicinity of the switching device 2). The sensor 3 is, for example, an acoustic sensor or a vibration sensor (including a strain sensor). The sensor 3 may also be a voltage sensor, a current sensor, an optical sensor (including an image sensor), a temperature sensor, etc.

[0014] The diagnostic device 1 diagnoses the switching device 2 based on a signal (sensor signal) from a sensor 3 provided in the switching device 2. The diagnostic device 1 may perform diagnosis based on the sensor signal itself (raw signal), or may perform diagnosis based on a processed sensor signal. The sensor signal or the processed sensor signal corresponds to the "raw signal" according to the present disclosure.

[0015] The diagnostic device 1 includes a processor 101, a memory 102, and a communication device 103. The processor 101 includes processing circuitry such as a central processing unit (CPU) and a microprocessing unit (MPU). The memory 102 includes volatile storage devices such as dynamic random access memory (DRAM) and static random access memory (SRAM), and nonvolatile storage devices such as a hard disk drive (HDD), a solid state drive (SSD), and a flash memory. The memory 102 stores a system program including an operating system (OS), a control program including computer-readable code, and various parameters for diagnosing the switching device 2. The processor 101 performs various arithmetic operations by reading the system program, the control program, and the parameters, and then storing and executing them in the memory 102. The communication device 103 is configured to communicate with devices outside the diagnostic device 1 under the control of the processor 101.

[0016] Although only one processor is illustrated in FIG. 1 , the diagnostic device 1 may include multiple processors. That is, the diagnostic device 1 includes one or more processors. The same applies to the memory 102. In this specification, the term "processor" is not limited to a processor in the narrow sense that executes processing using a stored program, but may also include hardwired circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Therefore, the term "processor" can also be interpreted as a processing circuit (circuitry or processing circuitry) whose processing is predefined by computer-readable code and / or hardwired circuitry.

[0017] The diagnostic system 100 further includes a server 41 and a terminal 42. The server 41 includes a database that stores the diagnostic results obtained by the diagnostic device 1. The server 41 may store data (so-called logs) that indicate the progress of signal processing performed by the diagnostic device 1. The terminal 42 includes a display that displays the diagnostic results obtained by the diagnostic device 1. The terminal 42 may include an alarm (warning light, alarm, etc.) that notifies the user of an abnormality in the opening and closing device 2 that has been discovered as a result of the diagnosis performed by the diagnostic device 1. The alarm may be provided in the diagnostic device 1.

[0018] The following describes an example in which the sensor 3 is an acoustic sensor, but similar processing can also be performed on signals (such as vibration signals) from sensors other than acoustic sensors.

[0019] Fig. 2 is a diagram showing the configuration of the switching device diagnostic system according to embodiment 1. Note that in Fig. 2, the server 41 and the terminal 42 (see Fig. 1) are omitted from the illustration in order to avoid cluttering the page.

[0020] As described above, the switchgear 2 is the electrical equipment to be diagnosed in this example, and is electrically connected to a power supply path from the power source 81 to the load 6 (including the power system). The switchgear 2 includes a circuit breaker 21 and a motor 22. The circuit breaker 21 is electrically connected to a power supply path to a power system (not shown). The motor 22 is an electromagnetic motor, and is configured to open and close the circuit breaker 21 in accordance with a control command from the diagnostic device 1. The operation of the circuit breaker 21 transitioning from a closed state to an open state is the opening operation of the switchgear 2, and the operation of the circuit breaker 21 transitioning from an open state to a closed state is the closing operation of the switchgear 2.

[0021] The circuit breaker 21 is provided with an acoustic sensor 31. The acoustic sensor 31 includes, for example, a microphone, and detects operation sounds (such as contact sounds between components) of the switchgear 2. The acoustic sensor 31 outputs an acoustic signal indicating the detection result to the diagnostic device 1.

[0022] The diagnostic device 1 includes an input unit 11, a signal processing unit 12, an output unit 13, and a control unit 14. The input unit 11 receives an acoustic signal from the acoustic sensor 31. The signal processing unit 12 performs signal processing on the acoustic signal to diagnose the switching device 2. The output unit 13 outputs the diagnosis result by the signal processing unit 12 to at least one of a server 41 and a terminal 42 (see FIG. 1 ). The output unit 13 may output the diagnosis result or an intermediate progress to a storage unit (memory 102) not shown. The control unit 14 outputs a control command to cause the switching device 2 to perform an opening operation or a closing operation.

[0023] Fig. 3 is a functional block diagram for explaining an outline of the function of the signal processing unit 12. Fig. 4 is a conceptual diagram for explaining signal processing by the signal processing unit 12. Fig. 5 is a diagram showing an example of an actual waveform.

[0024] 3 to 5, the signal processing unit 12 includes a filter 71, a short-time Fourier transform (STFT) unit 72, a spectral flux (SF) transform unit 73, a feature extraction unit 74, a storage unit 75, and a diagnosis unit 76.

[0025] The filter 71 passes signal components of a certain frequency band of the acoustic signal from the input unit 11 and outputs the signal components to the short-time Fourier transform unit 72. The filter 71 may be an analog filter or a digital filter. Depending on the frequency band of the acoustic signal, the filter 71 may not be essential and may be omitted.

[0026] The short-time Fourier transform unit 72 performs a time-frequency transform for each predetermined time width on the signal that has passed through the filter 71. More specifically, it calculates a signal indicating the spectral intensity for each predetermined time width (hereinafter also referred to as an "intensity signal") according to the following equation (1).

[0027] The acoustic signal is represented by x, the window function by w, the intensity by I, the time by t (and τ), and the frequency by f. The signal after the short-time Fourier transform is represented by a three-dimensional waveform of time-frequency-intensity, and can be represented on a color map such as that shown in the center of FIG. 5. In the color map, the horizontal axis represents time, the vertical axis represents frequency, and the depth axis (the axis perpendicular to the paper surface) represents a color corresponding to the intensity I. The short-time Fourier transform unit 72 outputs the generated intensity signal I(t, f) to the SF transform unit 73.

[0028] As the time-frequency transformation, in addition to the short-time Fourier transform, a continuous wavelet transform (CWT), a discrete wavelet transform (DWT), a Stockwell transform, etc. may be used.

[0029] The SF transform unit 73 converts the frequency domain signal (three-dimensional waveform of time-frequency-intensity) for each time width into a time domain signal (two-dimensional waveform with the horizontal axis being the time axis) that indicates spectral fluctuations by summing the intensities in the frequency domain signal (three-dimensional waveform of time-frequency-intensity) for each time width. More specifically, the SF transform unit 73 generates a spectral flux signal by performing a spectral flux transform on the intensity signal I(t, f) generated by the short-time Fourier transform unit 72. The spectral flux transform is expressed as in the following equation (2).

[0030] SF represents the spectral flux value. H is a function that performs half-wave rectification to emphasize the rising edge of the intensity signal I, returning the value unchanged for zero or positive values ​​and zero for negative values ​​(see equation (3) below). L represents the maximum frequency (upper limit of frequency).

[0031] As can be seen from equation (2), the spectral flux signal is calculated by calculating, for each frequency f, the amount of change in intensity I at the same frequency f (the difference between the intensity I(t) at a certain time and the intensity I(t-1) at the previous time), and then summing these amounts of change across all frequencies. This generates a signal SF(t) indicating the temporal change in the spectral flux value (hereinafter also referred to as the "spectral flux signal"). An example of the waveform of a spectral flux signal is shown at the bottom of FIG. 5. In the figure, the spectral flux value is referred to as the SF value. The spectral flux signal corresponds to the "conversion signal" according to the present disclosure.

[0032] In this example, the SF transform unit 73 generates a signal SF(t) indicating a temporal change in the spectral flux value across the entire frequency band by summing the differences in intensity I for all frequencies f for each time width. However, any transform formula may be used as long as it is possible to detect changes in the intensity signal I(t, f), i.e., to emphasize the rising and / or falling edges of the intensity signal I(t, f). For example, a transform unit (not shown) provided instead of the SF transform unit 73 may sum the differences in intensity I between adjacent frequencies f over a specified time length. The SF transform unit 73 outputs the spectral flux signal SF(t) to the feature extractor 74.

[0033] The feature extraction unit 74 detects a change in the spectral flux signal SF(t) generated by the SF conversion unit 73. The feature extraction unit 74 extracts one or more feature quantities related to the detected change. The method of extracting the feature quantities by the feature extraction unit 74 will be described in detail later. The feature extraction unit 74 outputs the extracted one or more feature quantities to the diagnosis unit 76.

[0034] The storage unit 75 stores criteria (hereinafter referred to as "diagnostic criteria") for diagnosing the switching device 2. The diagnostic criteria are determined depending on the type of feature amount described below, and are, for example, a reference intensity, a reference amount of change, a reference frequency, a reference time, or a reference waveform. The storage unit 75 outputs the diagnostic criteria to the diagnosing unit 76.

[0035] The diagnosing unit 76 diagnoses the switching device 2 by comparing one or more feature amounts extracted by the feature amount extracting unit 74 with the diagnostic criteria stored in the storage unit 75. The diagnostic method used by the diagnosing unit 76 will be described in detail later. The diagnosing unit 76 outputs the diagnosis result to the output unit 13 (see FIG. 2 ).

[0036] The output unit 13 outputs the diagnosis result to the server 41 and the terminal 42. The output unit 13 may store the diagnosis result in the memory 102. Although not shown, data indicating the progress of the signal processing by the signal processing unit 12 (such as a signal after short-time Fourier transform or a spectral flux signal) may be stored in the memory 102 or the server 41.

[0037] <Features> Fig. 6 is a diagram showing a first example of a change detected in a spectral flux signal. The horizontal axis represents time, and the vertical axis represents the spectral flux value. The same applies to the subsequent Figs. 7 to 9. The feature extraction unit 74 may detect the occurrence of a peak (especially a peak value greater than a threshold) in the spectral flux signal. In this case, the feature extraction unit 74 may extract features based on the peak time and / or peak value.

[0038] 7 shows a second example of a change detected in the spectral flux signal. The feature extractor 74 may detect that the spectral flux signal has exceeded a threshold. In this case, the feature extractor 74 may extract a feature based on the time at which the spectral flux signal exceeded the threshold (which may be the rise time or the fall time), the time difference between the rise time and the fall time, or a spectral flux value (e.g., a peak value) greater than the threshold.

[0039] 8 is a diagram illustrating a first example of a feature. In this example, four peaks are detected in the spectral flux signal. The feature extractor 74 may extract, as the feature, time differences ΔTa, ΔTb, and ΔTc between two adjacent peaks among the four peaks.

[0040] FIG. 9 is a diagram illustrating a second example of feature quantities. The horizontal axis represents time. The upper vertical axis represents the spectral flux value, and the lower vertical axis represents the intensity of the acoustic signal. The feature quantity extraction unit 74 may extract, as a feature quantity, the frequency of the acoustic signal x(t) at each time when four peaks are detected. Although not shown, the feature quantity extraction unit 74 may also extract, as a feature quantity, the frequency (intensity on a color map) of the intensity signal I(t, f) at each time when four peaks are detected.

[0041] 10 is a diagram illustrating a third example of the feature quantities. The horizontal axis represents time, and the vertical axis represents the spectral flux value. The feature quantity extractor 74 may extract four peak values ​​(or the amount of change in the spectral flux value before and after the peak) ΔSFa, ΔSFb, ΔSFc, and ΔSFd as the feature quantities.

[0042] 11 is a diagram illustrating a fourth example of the feature. The horizontal axis represents time, and the vertical axis represents the intensity of the acoustic signal. The feature extractor 74 may extract, as the feature, the decay time τa or τb of the acoustic signal at the time when a peak is detected in the spectral flux signal (typically, the time required for the amplitude of the acoustic signal to become 1 / e of the amplitude before attenuation).

[0043] <Processing Flow> If there is a time interval between the contact opening operation and the contact closing operation of the switchgear 2, the power supply from the power source 81 to the load 6 via the switchgear 2 may be cut off, causing a power outage in the load 6. Therefore, in the first embodiment, the diagnostic device 1 performs a contact closing operation immediately after the contact opening operation of the switchgear 2, thereby preventing the cutoff of the power supply to the load 6 (and the resulting power outage in the power system).

[0044] 12 is a flowchart showing a first example of a processing procedure of processing executed in the first embodiment. The processing shown in this flowchart is called from a main routine (not shown) and executed when a predetermined condition is met (for example, when a predetermined time arrives). Each step is realized by software processing by the diagnostic device 1 (more specifically, the processor 101), but may also be realized by hardware (electrical circuits) arranged within the diagnostic device 1. The same applies to the processing shown in the other flowcharts. Hereinafter, steps will be abbreviated as S.

[0045] 12 , it is assumed that the switching device 2 is turned on, thereby supplying power from the power supply 81 to the load 6. Referring to FIGS. 1 , 2 and 12 , in S11, the diagnostic device 1 outputs a control command to the switching device 2 to cause the switching device 2 to perform an opening operation. Then, the diagnostic device 1 performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the opening operation of the switching device 2 (S7).

[0046] FIG. 13 is a flowchart showing an example of a signal conversion process. Referring to FIGS. 2 and 13 , the diagnostic device 1 first acquires an acoustic signal associated with the opening operation of the switchgear 2 from the acoustic sensor 31 (S71). The diagnostic device 1 calculates an intensity signal by performing a short-time Fourier transform on the acoustic signal in the frequency band that has passed through the filter (S72). As described above, the diagnostic device 1 may perform a continuous wavelet transform, a discrete wavelet transform, or a Stockwell transform instead of the short-time Fourier transform. Furthermore, the diagnostic device 1 performs a spectral flux transform on the intensity signal to generate a spectral flux signal that indicates a time change in the spectral flux value (S73). The spectral flux transform is a process of summing intensity differences for all frequencies for each time width. Alternatively, the diagnostic device 1 may sum intensity differences between adjacent frequencies over a specified time length.

[0047] 12 , the diagnostic device 1 outputs a control command to the switching device 2 to cause the switching device 2 to perform a closing operation. In the first embodiment, the time from when the control command to cause the switching device 2 to perform an opening operation is output in S11 to when the control command to cause the switching device 2 to perform a closing operation is output in S12 is set to be sufficiently short (for example, less than one second) to prevent interruption of the power supply to the load 6. Thereafter, the diagnostic device 1 performs a signal conversion process (S7) to generate a spectral flux signal from an acoustic signal accompanying the closing operation of the switching device 2. Thereafter, the diagnostic device 1 performs feature extraction (S8) and abnormality diagnosis (S9) in this order.

[0048] In this example, the short-time Fourier transform (S72) and the spectral flux transform (S73) processes related to the opening operation of the switchgear 2 are executed between the opening operation and the closing operation of the switchgear 2. However, these processes may be executed after acquiring the acoustic signal associated with the closing operation of the switchgear 2. In other words, the diagnostic device 1 may first acquire the acoustic signal associated with the opening operation of the switchgear 2 and the acoustic signal associated with the closing operation of the switchgear 2, and then execute the signal processing (short-time Fourier transform and spectral flux transform) on these signals afterward. Conversely, the diagnostic device 1 may execute some or all of the feature extraction described below in addition to the short-time Fourier transform and the spectral flux transform between the opening operation and the closing operation of the switchgear 2.

[0049] 2 and 14, in S81, the diagnostic device 1 extracts, as a feature, a time difference between a plurality of peaks detected in each of two spectral flux signals (a spectral flux signal generated from an acoustic signal accompanying the opening operation of the switchgear 2 and a spectral flux signal generated from an acoustic signal accompanying the closing operation of the switchgear 2) (see FIG. 8).

[0050] In S82, the diagnostic device 1 extracts, as a feature, the frequency of the acoustic signal at the time when a peak is detected in each of the two spectral flux signals (see FIG. 9).

[0051] In S83, the diagnostic device 1 extracts one or more peak values ​​from each of the two spectral flux signals as feature quantities (see FIG. 10).

[0052] In S84, the diagnostic device 1 extracts, as a feature, the decay time of the acoustic signal at the time when a peak is detected in each of the two spectral flux waveforms (see FIG. 11).

[0053] The order of the four processes S81 to S84 is not particularly limited, and these four processes can be executed in any order. Instead of all four processes, only one, two, or three of the four processes may be executed.

[0054] FIG. 15 is a flowchart showing an example of a procedure for abnormality diagnosis. Referring to FIGS. 1, 3, and 15, the diagnostic device 1 determines whether each of the extracted one or more feature quantities satisfies a predetermined diagnostic criterion (S91). If at least one feature quantity satisfies the diagnostic criterion (YES in S91), the diagnostic device 1 diagnoses that an abnormality associated with the feature quantity has occurred in the switching device 2 (S92). The diagnostic device 1 then notifies the external server 41 or terminal 42 of the type of abnormality that has occurred (S93). On the other hand, if all feature quantities do not satisfy the diagnostic criterion (NO in S91), the diagnostic device 1 diagnoses that the switching device 2 is normal (S94). Although not shown, the diagnostic device 1 may notify the external server 41 or terminal 42 of the diagnosis result that the switching device 2 is normal.

[0055] Fig. 16 is a flowchart showing a second example of the processing procedure of the processing executed in Embodiment 1. The processing shown in Fig. 16 differs from the processing shown in Fig. 12 in that it includes the signal conversion processing (S7) three times, more specifically, in that it includes the signal conversion processing based on the acoustic signal acquired in the initial state in which the opening and closing device 2 is closed. The other processing is the same as the processing shown in Fig. 12, and therefore description thereof will not be repeated.

[0056] Normally, an opportunity to diagnose the switchgear 2 is only available under circumstances where interruption of the power supply to the load 6 is not a problem. In contrast, in the first embodiment, the time difference between the opening operation and closing operation of the switchgear 2 is sufficiently short, in other words, the opening operation and closing operation of the switchgear 2 are performed successively, so that the switchinggear 2 can be diagnosed while suppressing interruption of the power supply to the load 6 such as the power system. This makes it easy to ensure an opportunity to diagnose the switchinggear 2, and therefore it becomes possible to diagnose the switchinggear 2 at a desired timing or more frequently.

[0057] Second Embodiment Fig. 17 is a diagram showing the configuration of a switchgear diagnostic system according to a second embodiment. The diagnostic system 100A differs from the diagnostic system 100 according to the first embodiment (see Fig. 2) in that it further includes a power storage device 8. The power storage device 8 may be connected in parallel to the load 6 (such as an industrial power storage system) as shown in Fig. 17. Although not shown, the power storage device 8 may also be connected in series to the load 6. In this case, the power storage device 8 may be an uninterruptible power system (UPS) or a multiple power compensator (MPC).

[0058] Fig. 18 is a flowchart showing a first example of a processing procedure of processing executed in embodiment 2. The processing shown in Fig. 18 differs from the processing shown in Fig. 12 in that the opening operation and closing operation of the switchgear 2 are repeated.

[0059] 17 and 18 , diagnostic device 1 outputs a control command to switchgear 2 to cause switchgear 2 to perform an opening operation (S31). Then, diagnostic device 1 performs signal conversion to generate a spectral flux signal from an acoustic signal accompanying the opening operation of switchgear 2 (S7).

[0060] In S32, the diagnostic device 1 determines whether a predetermined time has elapsed since the opening operation of the switching device 2. The diagnostic device 1 waits until the predetermined time has elapsed (NO in S32), and when the predetermined time has elapsed (YES in S32), it outputs a control command to the switching device 2 to cause the switching device 2 to perform a closing operation (S33).The diagnostic device 1 then performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the closing operation of the switching device 2 (S7).

[0061] In S34, the diagnostic device 1 determines whether a condition for ending the repeated opening and closing operations of the switching device 2 is met. The condition is met when the time during which the repeated opening and closing operations of the switching device 2 have continued reaches a specified time, when the number of repetitions reaches a specified number, when a specified time has passed, or when a specified time has arrived. If the condition is not met (NO in S34), the diagnostic device 1 returns the process to S31. If the condition is met (YES in S34), the diagnostic device 1 ends the repeated opening and closing operations of the switching device 2. Then, the diagnostic device 1 executes feature extraction (S8) and abnormality diagnosis (S9).

[0062] Fig. 19 is a flowchart showing a second example of the processing procedure of the processing executed in embodiment 2. The processing shown in Fig. 19 differs from the processing shown in Fig. 18 in that processing in S42 is included instead of processing in S32 for determining whether time has elapsed since the contact-opening operation of the switching device 2.

[0063] In S42, the diagnostic device 1 determines whether a trigger for performing a closing operation of the switching device 2 has been detected. The trigger may be a signal indicating that an engaging element included in the switching device 2 will (or has) operated (typically a signal indicating the arrival of the operating time of the engaging element). The trigger may also be a contact operation signal of the switching device 2 (a signal resulting from the operation of a contact included in the switching device 2). The diagnostic device 1 waits until the trigger is detected (NO in S42). When the trigger is detected (YES in S42), the diagnostic device 1 outputs a control command to the switching device 2 to cause the switching device 2 to perform a closing operation (S43). The diagnostic device 1 then performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the closing operation of the switching device 2 (S7). The subsequent processes in S44, S8, and S9 are similar to the corresponding processes shown in FIG. 18 .

[0064] As described above, in the second embodiment, the power storage device 8 is connected in series or parallel to the load 6. Even if the power supply from the power source 5 to the load 6 is interrupted by the opening operation of the switchgear 2, power is supplied from the power storage device 8 to the load 6, thereby suppressing a power outage of the load 6. Therefore, according to the second embodiment, it is possible to increase the number of opportunities to diagnose the switchgear 2.

[0065] Embodiment 3. Figure 20 is a diagram showing the configuration of a switching device diagnostic system according to embodiment 3. The diagnostic system 100B differs from the diagnostic system 100 according to embodiment 1 (see Figure 2) in that it further includes a relay 9. The relay 9 is a bypass switch that is connected in parallel to the switching device 2 and is provided to bypass the switching device 2. The relay 9 is controlled in accordance with a control command from the diagnostic device 1.

[0066] FIG. 21 is a flowchart showing an example of a processing procedure executed in the third embodiment. Referring to FIGS. 20 and 21 , diagnostic device 1 first outputs a control command to relay 7 to close relay 9 (S51). Next, diagnostic device 1 outputs a control command to switching device 2 to cause switching device 2 to perform an opening operation (S52). Diagnostic device 1 performs signal conversion to generate a spectral flux signal from an acoustic signal accompanying the opening operation of switching device 2 (S7). Furthermore, diagnostic device 1 outputs a control command to switching device 2 to cause switching device 2 to perform a closing operation (S53). Diagnostic device 1 performs signal conversion to generate a spectral flux signal from an acoustic signal accompanying the closing operation of switching device 2 (S7). Then, diagnostic device 1 performs feature extraction (S8) and abnormality diagnosis (S9).

[0067] As described above, in the third embodiment, the relay 9 is connected in parallel to the switchgear 2. By closing the relay 9, the power supply from the power source 5 to the load 6 is maintained even during the opening operation of the switchgear 2, thereby suppressing power outages in the load 6. Therefore, according to the third embodiment, it is possible to increase the number of opportunities to diagnose the switchgear 2.

[0068] In the configuration of the diagnostic system 100B according to the third embodiment, the diagnostic device 1 may also control the switching device 2 so that the opening operation and the closing operation of the switching device 2 are repeated and the closing operation is performed after a predetermined time has elapsed since the opening operation (see FIG. 18). Furthermore, the diagnostic device 1 may also control the switching device 2 so that the opening operation and the closing operation of the switching device 2 are repeated and the closing operation is performed in response to a trigger (see FIG. 19).

[0069] Fourth Embodiment Fig. 22 is a diagram showing the configuration of a switching device diagnostic system according to a fourth embodiment. The diagnostic system 100C differs from the diagnostic system 100 according to the first embodiment (see Fig. 2) in that it includes two switching devices 2A and 2B. The internal configuration of each of the switching devices 2A and 2B is equivalent to the internal configuration of the switching device 2A according to the first embodiment. The switching device 2A is connected between a power source 81A and a load 6. The switching device 2B is connected between a power source 81B and the load 6. In other words, the power supply paths from the power sources 81A and 81B to the load 6 are duplicated. Note that the power sources 81A and 81B may be the same power source.

[0070] Fig. 23 is a flowchart showing an example of a processing procedure of processing executed in embodiment 4. With reference to Fig. 22 and Fig. 23, in S61, diagnostic device 1 outputs a control command to opening and closing devices 2A and 2B so that both opening and closing devices 2A and 2B are brought into the on state (or, if already in the on state, maintain the on state).

[0071] In S62, the diagnostic device 1 outputs a control command to the switching device 2A to cause the switching device 2A to perform an opening operation. The diagnostic device 1 performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the opening operation of the switching device 2A (S7). Furthermore, the diagnostic device 1 outputs a control command to the switching device 2A to cause the switching device 2A to perform a closing operation (S63). The diagnostic device 1 performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the closing operation of the switching device 2A (S7). Thereafter, the diagnostic device 1 performs feature extraction (S8) and abnormality diagnosis (S9).

[0072] In S64, the diagnostic device 1 outputs a control command to the switching device 2B to cause the switching device 2B to perform an opening operation. The diagnostic device 1 performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the opening operation of the switching device 2B (S7). Furthermore, the diagnostic device 1 outputs a control command to the switching device 2B to cause the switching device 2B to perform a closing operation (S65). The diagnostic device 1 performs signal conversion to generate a spectral flux signal from the acoustic signal accompanying the closing operation of the switching device 2B (S7). Thereafter, the diagnostic device 1 performs feature extraction (S8) and abnormality diagnosis (S9).

[0073] In this example, the diagnostic device 1 sequentially diagnoses the switching device 2A and the switching device 2B. The diagnostic device 1 may sequentially diagnose three or more switching devices. When three or more switching devices are to be diagnosed, some of the three or more switching devices (switching devices other than those to be diagnosed) may be turned on, and then the remaining switching devices may be diagnosed. Conversely, only the switching device 2A (only one of the switching devices 2A and 2B) may be diagnosed.

[0074] As described above, in the fourth embodiment, the two switching devices 2A, 2B are connected in parallel to each other. By maintaining one of the two switching devices 2A, 2B in the on state, the power supply from the power source 5 to the load 6 is maintained even when the other device is opening contacts, thereby suppressing power outages in the load 6. Therefore, according to the fourth embodiment, it is possible to increase the number of opportunities to diagnose the switching device 2.

[0075] In the configuration of the diagnostic system 100C according to the fourth embodiment, the diagnostic device 1 may also control the switching device 2 so that the opening operation and the closing operation of the switching device 2 are repeated and the closing operation is performed after a predetermined time has elapsed since the opening operation (see FIG. 18). Furthermore, the diagnostic device 1 may also control the switching device 2 so that the opening operation and the closing operation of the switching device 2 are repeated and the closing operation is performed in response to a trigger (see FIG. 19).

[0076] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0077] 100, 100A, 100B, 100C Diagnostic system, 1 Diagnostic device, 101 Processor, 102 Memory, 103 Communication equipment, 11 Input unit, 12 Signal processing unit, 13 Output unit, 14 Control unit, 2, 2A, 2B Switchgear, 21 Circuit breaker, 22 Motor, 3 Sensor, 31 Acoustic sensor, 41 Server, 42 Terminal, 5, 5A, 5B Power supply, 6 Load, 71 Filter, 72 Short-time Fourier transform unit, 73 Spectral flux transform unit, 74 Feature extraction unit, 75 Memory unit, 76 Diagnostic unit, 8 Storage device, 9 Relay.

Claims

1. A diagnostic device comprising: a control unit that controls a switching device electrically connected to a power supply path from a power source to a load; a signal conversion unit that calculates an intensity signal that indicates a time change in spectral intensity by performing time-frequency conversion for each time width on an original signal that indicates a time change in an electrical device electrically connected to the load, and generates a converted signal by summing the intensity signals over time or frequency; a feature extraction unit that extracts features from the converted signal; and a diagnostic unit that diagnoses the electrical device based on the features, wherein the control unit causes the switching device to perform an opening operation and a closing operation while continuing to supply power to the load, and the signal conversion unit generates the converted signal based on the original signal emitted from the electrical device in response to the control of the switching device by the control unit.

2. The diagnostic device according to claim 1, wherein the electrical equipment includes the switching device.

3. A diagnostic device according to claim 1 or 2, wherein the original signal is an acoustic signal representing a sound generated by the electrical equipment.

4. The diagnostic device according to claim 1 or 2, wherein the original signal is a vibration signal indicative of vibration of the electrical device.

5. A diagnostic device according to any one of claims 1 to 4, wherein the control unit controls the switching device to perform the contact opening operation and the contact closing operation from an initial state in which the switching device is closed, and the signal conversion unit generates the converted signal based on the original signal acquired from the initial state until after the contact opening operation and the contact closing operation have been performed.

6. A diagnostic device according to any one of claims 1 to 5, wherein the control unit controls the switching device so that the opening operation and the closing operation are performed in a short time that can prevent interruption of the power supply to the load.

7. A diagnostic device according to any one of claims 1 to 6, wherein the control unit controls the switching device so that the opening operation and the closing operation are repeated and the closing operation is performed after a specified time has elapsed since the opening operation.

8. A diagnostic device according to any one of claims 1 to 6, wherein the control unit controls the switching device so that the opening operation and the closing operation are repeated and the closing operation is performed in response to a trigger.

9. The diagnostic device according to claim 8, wherein the trigger is the operation of an engaging part included in the opening and closing device.

10. The diagnostic device of claim 8, wherein the trigger is a change in a signal indicative of operation of the contacts of the switching device.

11. A diagnostic system comprising: the diagnostic device according to any one of claims 1 to 9; and a plurality of switchgears, each including the switchgear and electrically connected to a power supply path from the power source or another power source to the load, wherein the control unit causes some of the switchgears to perform the contact opening operation and the contact closing operation while some of the switchgears remain in a closed state.

12. A diagnostic system comprising: the diagnostic device according to any one of claims 1 to 9; and an electric storage device electrically connected to the load.

13. A diagnostic system comprising: the diagnostic device according to any one of claims 1 to 9; and a relay connected in parallel to the switching device between the power source and the load, wherein the control unit controls the switching device to perform the opening operation and the closing operation while the relay is closed.

14. A diagnostic method comprising the steps of: controlling a switchgear electrically connected to a power supply path from a power source to a load; calculating an intensity signal indicating a time change in spectral intensity by performing time-frequency transformation for each time width on an original signal indicating a time change of an electrical device electrically connected to the load, and generating a converted signal by summing the intensity signals over time or frequency; extracting feature amounts from the converted signal; and diagnosing the electrical device based on the feature amounts, wherein the generating step includes the steps of causing the switchgear to perform contact opening and closing operations while continuing to supply power to the load, and generating the converted signal based on the original signal emitted from the electrical device as a result.

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