Transformer bushing head outlet device fastening status monitoring system and evaluation method

Abstract

The present application provides a transformer bushing head outlet device tightness status monitoring system and evaluation method, the system includes a radar reflector, a millimeter-wave radar radio frequency transmitting device, a data acquisition device, and a tightness status evaluation device; since the material properties of the bushing head outlet device will result in poor reflection signal effect and most of the energy will be absorbed, the present application fixedly connects the radar reflector to the bushing head outlet device of the transformer, so that the millimeter-wave radar radio frequency transmitting device can transmit a signal to the radar reflector and receive the reflected signal of the radar reflector. In addition, the present application also uses a data acquisition device to synchronously collect the reflected signal of the radar reflector received by the millimeter-wave radar radio frequency transmitting device and the load current signal of the transformer, and sends the collected reflected signal and load current signal to the tightness status evaluation device, so that the tightness status evaluation device can evaluate the tightness status of the bushing head outlet device.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a system and method for monitoring the tightness status of a transformer bushing head outlet device. Background Art

[0002] The tightness of the transformer bushing's lead-out device (e.g., the general cap) is crucial to its safe operation. Loose connections can easily lead to excessive contact resistance and heat generation. Furthermore, loose connections increase the probability of seal failure, allowing moisture to easily enter the bushing, further increasing operational safety risks.

[0003] Currently, infrared imaging can detect heating conditions at the connection points of the outlet device, but this can only be done during periodic inspections, not online monitoring. Furthermore, this method cannot determine whether the connection is loose. Vibration monitoring technology is widely used, but because the outer sheath of the casing is a porcelain bottle or composite material with an umbrella skirt structure, the vibration accelerometer cannot be placed on the outer sheath. If it is placed in the area of the head outlet device, it will be affected by the high potential, and the internal electronic components of the vibration accelerometer are susceptible to electromagnetic interference. Furthermore, the signal transmission cable cannot be placed at high potential. Laser Doppler vibrometers are often used for measuring small-amplitude, high-frequency vibrations at a single target or a single measuring point. They have high requirements for the test environment, are large in size and power consumption, and are expensive.

[0004] Therefore, it is urgent to design a system that can monitor the connection tightness status of the transformer bushing head outlet device in real time and a method for evaluating the tightness status. Summary of the Invention

[0005] The purpose of this application is to solve at least one of the above-mentioned technical defects, especially the technical defect that the prior art lacks a system for real-time monitoring of the connection tightness status of the transformer bushing head outlet device and a method for evaluating the tightness status.

[0006] The present application provides a system for monitoring the fastening state of a transformer bushing head outlet device, the system comprising: a radar reflector, a millimeter wave radar radio frequency transmitting device, a data acquisition device, and a fastening state evaluation device;

[0007] The radar reflector is fixedly connected to the bushing head outlet device of the transformer;

[0008] The millimeter wave radar radio frequency transmitting device is used to transmit a signal to the radar reflector and receive a reflected signal from the radar reflector;

[0009] The data acquisition device is used to synchronously acquire the reflection signal of the radar reflector received by the millimeter-wave radar radio frequency transmitting device and the load current signal of the transformer, and send the acquired reflection signal and load current signal to the fastening state evaluation device;

[0010] The fastening state evaluation device is used to evaluate the fastening state of the sleeve head outlet device according to the reflection signal and the load current signal, and output a state evaluation result.

[0011] Optionally, the radar reflector adopts an angle emitter;

[0012] The corner emitter is a random shape formed by a polished stainless steel surface.

[0013] Optionally, each corner of the corner emitter is chamfered to reduce the electric field intensity at each corner.

[0014] Optionally, the data acquisition device acquires the reflected signal of the radar reflector received by the millimeter-wave radar radio frequency transmitting device and the load current signal of the transformer according to a preset data sampling rate;

[0015] Wherein, the preset data sampling rate is not less than 4kHz.

[0016] Optionally, when collecting the load current signal of the transformer, the data collection device collects the load current signal through a transformer bushing current transformer, or collects the load current signal through a current transformer on a busbar of the transformer.

[0017] The present application further provides a method for assessing the tightening state of a transformer bushing head outlet device, which is applied to a tightening state assessment device in a monitoring system for the tightening state of a transformer bushing head outlet device according to any one of the above embodiments. The method comprises:

[0018] Obtaining the rated load current of the transformer, the reflected signal currently collected by the data acquisition device, and the load current signal of the transformer, wherein the reflected signal is a reflected signal of a radar reflector received by a millimeter-wave radar radio frequency transmitting device;

[0019] Calculating a target load rate according to the rated load current of the transformer and the load current signal, and determining a target load rate interval within which the target load rate lies;

[0020] Determining current feature values corresponding to different features of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range, and obtaining historical feature values corresponding to corresponding features in the target load rate range within a preset historical period;

[0021] The current feature value corresponding to each feature is compared with the historical feature value, and the tightness of the transformer bushing head outlet device is evaluated based on the comparison results.

[0022] Optionally, determining the target load rate interval in which the target load rate lies includes:

[0023] Divide the transformer load rate into multiple load rate intervals according to a preset interval division method;

[0024] The target load rate is compared with each load rate interval to determine the target load rate interval in which the target load rate is located.

[0025] Optionally, the characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range include amplitude response, phase response, signal power proportion in a specific frequency band, and respective relative standard deviations;

[0026] The determining of current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range includes:

[0027] determining a first amplitude and a first phase of the reflected signal at a first specific frequency, and a second amplitude and a second phase of the load current signal at a second specific frequency, and calculating a current amplitude response and a current amplitude response deviation based on the first amplitude and the second amplitude, and calculating a current phase response and a current phase response deviation based on the first phase and the second phase; wherein the first specific frequency is twice the second specific frequency;

[0028] Calculate the signal power spectrum of the reflected signal, and determine the current signal power ratio and the current power ratio deviation of a specific frequency band in the signal power spectrum, wherein the specific frequency band is a frequency band above 1000 Hz.

[0029] Optionally, before determining current feature values corresponding to different features of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range, the method further includes:

[0030] The reflected signal is aligned with the load current signal so that a phase angle of the load current signal is 0°.

[0031] Optionally, comparing the current characteristic value corresponding to each characteristic with the historical characteristic value, and evaluating the fastening state of the transformer bushing head outlet device according to the comparison result, includes:

[0032] After comparing the current feature value of each feature with the historical feature value, the feature increment of each feature is determined;

[0033] Determine whether the feature increment of each feature exceeds the preset increment threshold of each feature;

[0034] If the feature increments of all features exceed their respective preset increment thresholds, it is determined that the fastening state of the transformer bushing head outlet device is abnormal;

[0035] If the feature increment of at least one feature does not exceed the corresponding preset increment threshold, it is determined that the fastening state of the transformer bushing head outlet device is normal.

[0036] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0037] The present application provides a system and method for monitoring the tightness status of a transformer bushing head outlet device. The system includes a radar reflector, a millimeter-wave radar radio frequency transmitter, a data acquisition device, and a tightness status evaluation device. Because the material properties of the bushing head outlet device result in poor reflected signal quality and most of the energy is absorbed, the present application fixedly connects the radar reflector to the transformer bushing head outlet device. This allows the millimeter-wave radar radio frequency transmitter to transmit signals to the radar reflector and receive reflected signals from the radar reflector. Furthermore, the present application uses a data acquisition device to synchronously collect the radar reflector's reflected signal received by the millimeter-wave radar radio frequency transmitter and the transformer's load current signal, and transmits the collected reflected signal and load current signal to the tightness status evaluation device. The tightness status evaluation device then evaluates the tightness status of the bushing head outlet device based on the reflected signal and load current signal transmitted in real time by the data acquisition device, and outputs a status evaluation result. The present application utilizes the principles of continuous wave microwave radar technology to measure the vibration displacement of the bushing head outlet device and evaluate the connection tightness status. This eliminates the need for signal cabling and electromagnetic interference considerations, enabling real-time online monitoring and evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] Figure 1 A schematic structural diagram of a transformer bushing head outlet device fastening status monitoring system provided in an embodiment of the present application;

[0040] Figure 2 A flowchart of a method for evaluating the tightness status of a transformer bushing head outlet device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0042] At present, the infrared imaging method can detect the heating state of the connection of the outlet device, but it can only be done through regular inspections, and online monitoring cannot be achieved. In addition, this method cannot determine whether the connection position is loose. Vibration monitoring technology is widely used, but because the outer sheath of the casing is a porcelain bottle or composite material, and it is an umbrella skirt structure, the vibration acceleration sensor cannot be arranged on the outer sheath. If it is arranged in the head outlet device area, it will be affected by the high potential, and the internal electronic components of the vibration acceleration sensor are susceptible to electromagnetic interference, and the signal transmission cable cannot be arranged at a high potential. The laser Doppler vibrometer is often used for the measurement of micro-high-frequency vibrations of a single target or a single measuring point. It has high requirements for the test environment, the equipment volume and power consumption are large, and the cost is high. Based on this, the present application proposes the following technical solutions, see below for details:

[0043] In one embodiment, Figure 1 As shown, Figure 1 This is a structural schematic diagram of a transformer bushing head outlet device tightening status monitoring system provided in an embodiment of the present application; the present application provides a transformer bushing head outlet device tightening status monitoring system, the system comprising: a radar reflector, a millimeter wave radar radio frequency transmitting device, a data acquisition device, and a tightening status evaluation device.

[0044] The radar reflector is fixedly connected to the bushing head outlet device of the transformer.

[0045] The millimeter wave radar radio frequency transmitting device is used to transmit signals to the radar reflector and receive reflected signals from the radar reflector.

[0046] The data acquisition device is used to synchronously collect the reflection signal of the radar reflector received by the millimeter wave radar radio frequency transmitting device and the load current signal of the transformer, and send the collected reflection signal and load current signal to the tightening state evaluation device.

[0047] The fastening state evaluation device is used to evaluate the fastening state of the sleeve head outlet device according to the reflection signal and the load current signal, and output a state evaluation result.

[0048] In this embodiment, the millimeter-wave radar RF transmitter has a transmitting antenna and a receiving antenna, capable of transmitting millimeter waves in the 77GHz-81GHz frequency band. Therefore, this application utilizes the principles of continuous-wave microwave radar technology to measure the vibration displacement of the casing head outlet device and assess the connection tightness. This eliminates the need for signal cabling and electromagnetic interference considerations, enabling real-time online monitoring and assessment.

[0049] Specifically, due to the material properties of the transformer bushing head outlet device, the reflected signal effect is poor and most of the energy will be absorbed. Therefore, when the present application uses the principle of continuous wave microwave radar technology to realize the vibration displacement measurement and connection tightness status evaluation of the bushing head outlet device, the radar reflector can be fixedly connected to the bushing head outlet device of the transformer. In this way, the millimeter wave radar RF transmitting device can transmit a signal to the radar reflector and receive the reflected signal from the radar reflector, thereby avoiding the situation where the signal is directly transmitted to the bushing head outlet device and then absorbed by it, resulting in the inability to prepare to measure its tightness status.

[0050] Furthermore, when the present application realizes the vibration displacement measurement and connection tightness status evaluation of the sleeve head outlet device through the principle of continuous wave microwave radar technology, the data acquisition device can be used to synchronously collect the reflected signal of the radar reflector received by the millimeter wave radar RF transmitting device, and the data acquisition device can also collect the load current signal of the transformer, so that both can be sent to the tightness status evaluation device together, so that the tightness status evaluation device can evaluate the tightness status of the sleeve head outlet device according to the reflected signal and the load current signal, and output the status evaluation result.

[0051] It can be understood that the millimeter-wave radar RF transmitting device of the present application can be placed on the ground, hung on the wall, or anywhere else, as long as it can transmit signals to the radar reflector fixed on the outlet device of the casing head; and the radar reflector of the present application is mainly a radar wave reflector of different specifications made of metal plates according to different uses.

[0052] In the above embodiment, the system includes a radar reflector, a millimeter-wave radar RF transmitter, a data acquisition device, and a tightening state assessment device. Since the material properties of the bushing head outlet device result in poor reflection signal effect and most of the energy will be absorbed, the present application fixedly connects the radar reflector to the bushing head outlet device of the transformer, so that the millimeter-wave radar RF transmitter can transmit signals to the radar reflector and receive reflected signals from the radar reflector. In addition, the present application also uses a data acquisition device to synchronously collect the reflected signal of the radar reflector received by the millimeter-wave radar RF transmitter and the load current signal of the transformer, and sends the collected reflected signal and load current signal to the tightening state assessment device. In this way, the tightening state assessment device can evaluate the tightening state of the bushing head outlet device based on the reflected signal and load current signal transmitted in real time by the data acquisition device, and output the state assessment result. Among them, the present application uses the principle of continuous wave microwave radar technology to achieve vibration displacement measurement and connection tightening state assessment of the bushing head outlet device, without the need to lay signal cables or consider electromagnetic interference issues, and can achieve real-time online monitoring and assessment.

[0053] In one embodiment, the radar reflector is an angle emitter; the angle emitter is any shape formed by a polished stainless steel surface.

[0054] In this embodiment, the radar reflector can be a corner emitter. Corner emitters are categorized by material, primarily metal and coated. They are categorized by shape, primarily square, octagonal, hexagonal, and polygonal. They are further categorized by placement method, primarily fixed and hanging. This application can employ a fixed corner emitter, which can be made of polished stainless steel in any shape, such as a square, triangle, or fan. The specific configuration depends on the actual situation and is not limited here.

[0055] In one embodiment, each corner of the corner emitter is chamfered to reduce the electric field intensity at each corner.

[0056] In one embodiment, the data acquisition device collects the reflected signal of the radar reflector received by the millimeter-wave radar RF transmitting device and the load current signal of the transformer according to a preset data sampling rate; wherein the preset data sampling rate is not less than 4kHz.

[0057] In this embodiment, the data acquisition device can synchronously collect the reflected signal of the radar reflector received by the millimeter-wave radar RF transmitting device and the load current signal of the transformer, and transmit the data to the tightening state evaluation device as needed. During this process, the data acquisition device can set the data sampling rate Fs as needed, which is usually not less than 4kHz.

[0058] In one embodiment, when collecting the load current signal of the transformer, the data collection device collects the load current signal through the transformer bushing current transformer, or collects the load current signal through the current transformer on the transformer bus.

[0059] In this embodiment, when collecting the load current signal of the transformer, the data acquisition device can collect it through the transformer sleeve current transformer or the current transformer on the transformer bus. The specific selection can be made according to the actual situation and is not limited here.

[0060] In one embodiment, Figure 2 As shown, Figure 2 This is a flow chart of a method for assessing the tightness of a transformer bushing head outlet device provided in an embodiment of the present application. This application also provides a method for assessing the tightness of a transformer bushing head outlet device, which is applied to a tightness assessment device in a monitoring system for the tightness of a transformer bushing head outlet device according to any of the above embodiments. The method may include:

[0061] S110: Acquire the rated load current of the transformer, the reflected signal currently collected by the data acquisition device, and the load current signal of the transformer, wherein the reflected signal is a reflected signal of a radar reflector received by the millimeter-wave radar radio frequency transmitting device.

[0062] S120: Calculating a target load rate according to the rated load current of the transformer and the load current signal, and determining a target load rate interval in which the target load rate lies.

[0063] S130: Determine current feature values corresponding to different features of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range, and obtain historical feature values corresponding to corresponding features in the target load rate range within a preset historical period.

[0064] S140: Compare the current feature value corresponding to each feature with the historical feature value, and evaluate the fastening state of the transformer bushing head outlet device based on the comparison result.

[0065] In this embodiment, when evaluating the tightness state of the transformer bushing head outlet device, the transformer rated load current can be obtained first, and the currently collected reflection signal and the transformer load current signal can be obtained through the data acquisition device, wherein the reflection signal is the reflection signal of the radar reflector received by the millimeter-wave radar RF transmitting device collected by the data acquisition device; then, the tightness state evaluation device can calculate the target load rate based on the transformer rated load current and the current load current signal, and determine the target load rate interval in which the target load rate is located. Then, the present application can calculate the current characteristic values corresponding to all features affecting the tightness state of the transformer bushing head outlet device in the target load rate interval of the reflection signal and the load current signal, and obtain the historical characteristic values corresponding to the corresponding features in the target load rate interval within a preset historical period. Finally, the present application can compare the current characteristic value and the historical characteristic value corresponding to each feature, and evaluate the tightness state of the transformer bushing head outlet device based on the comparison result.

[0066] It can be understood that after obtaining the reflected signal and the load current signal, the present application can first determine all the characteristics in the reflected signal and the load current signal that affect the tightness of the transformer bushing head outlet device, such as the amplitude, phase, and frequency band of the vibration spectrum of the bushing head outlet device with abnormal state, etc., and compare the current characteristic value obtained with the historical characteristic value obtained in the preset historical period, so as to determine the changes in the amplitude, phase, and frequency band of the vibration spectrum of the bushing head outlet device with abnormal state over a period of time, and then judge the tightness of the transformer bushing head outlet device based on the changes, and obtain a more accurate evaluation result.

[0067] Furthermore, before calculating the current characteristic values corresponding to all the characteristics that affect the tightness state of the transformer bushing head outlet device in the target load rate range of the reflected signal and the load current signal, the present application can first calculate the target load rate based on the rated load current of the transformer and the current load current signal, and determine the target load rate range in which the target load rate is located. In this way, the calculation result of the current characteristic value can be divided into the target load rate range, and the historical characteristic values corresponding to the corresponding characteristics in the preset historical period can be obtained through the target load rate range, which is conducive to comparing the current characteristic value with the historical characteristic value to obtain a more accurate evaluation result.

[0068] In one embodiment, determining the target load rate interval in S120 may include:

[0069] S121: Divide the transformer load rate into multiple load rate intervals according to a preset interval division method.

[0070] S122: Compare the target load rate with each load rate interval to determine the target load rate interval in which the target load rate is located.

[0071] In this embodiment, when determining the target load rate interval in which the target load rate is located, the transformer load rate can be first divided into multiple load rate intervals according to a preset interval division method, and then the target load rate is compared with each load rate interval in turn to determine the target load rate interval in which the target load rate is located.

[0072] In a specific implementation, the transformer load rate in this application is generally set to 100%. Then, this application can compensate the load rate by 5%, dividing it into 20 intervals from 0 to 100%, and then compare the target load rate with each interval to determine the target load rate interval it is in. Of course, this application can also compensate the load rate by 10%, dividing it into 10 intervals from 0 to 100%, etc. The specific setting can be based on actual conditions and is not limited here.

[0073] In one embodiment, the characteristics of the reflected signal and the load current signal affecting the tightening state of the transformer bushing head outlet device in the target load rate range include amplitude response, phase response, signal power proportion in a specific frequency band, and respective relative standard deviations.

[0074] Determining current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range in S130 may include:

[0075] S131: Determine the first amplitude and first phase of the reflected signal at a first specific frequency, and the second amplitude and second phase of the load current signal at a second specific frequency, and calculate the current amplitude response and the current amplitude response deviation based on the first amplitude and the second amplitude, and calculate the current phase response and the current phase response deviation based on the first phase and the second phase; wherein the first specific frequency is twice the second specific frequency.

[0076] S132: Calculate the signal power spectrum of the reflected signal, and determine the current signal power ratio and the current power ratio deviation of a specific frequency band in the signal power spectrum, wherein the specific frequency band is a frequency band above 1000 Hz.

[0077] In this embodiment, when calculating the current characteristic values corresponding to all features affecting the tightness state of the transformer bushing head outlet device in the target load rate range of the reflected signal and the load current signal, the features affecting the tightness state of the transformer bushing head outlet device can be calculated in sequence. The features include but are not limited to amplitude response, phase response, signal power ratio in a specific frequency band, and their respective relative standard deviations.

[0078] Specifically, when calculating the amplitude response, phase response and relative standard deviation of the reflected signal and the load current signal, the present application can first determine the first amplitude and first phase of the reflected signal at the first specific frequency, and the second amplitude and second phase of the load current signal at the second specific frequency, and calculate the current amplitude response and the current amplitude response deviation based on the first amplitude and the second amplitude, and calculate the current phase response and the current phase response deviation based on the first phase and the second phase, wherein the first specific frequency in the present application is twice the second specific frequency.

[0079] For example, the present application can perform Fourier transform on the reflected signal and the load current signal to extract the amplitude V of the reflected signal at a frequency of 100 Hz. 100 and phase angle ɑ 100 , and extract the 50Hz frequency amplitude of the load current signal I 50 and phase angle θ 50 , and calculate the current amplitude response and current phase response using the following formulas:

[0080]

[0081] Next, the present application can obtain multiple amplitude responses and phase responses currently collected, and calculate the relative standard deviation corresponding to the current amplitude response, that is, the current amplitude response deviation, and the relative standard deviation corresponding to the current phase response, that is, the current phase response deviation.

[0082] It can be understood that since the reflected signal reflects a mechanical vibration signal, which is excited by electromagnetic force, and the electromagnetic force is twice the current frequency, this application takes 100Hz when calculating the amplitude and phase angle of the reflected signal, and takes 50Hz when calculating the amplitude and phase angle of the load current signal.

[0083] Furthermore, the present application can also calculate the signal power spectrum of the reflected signal and determine the current signal power ratio and the current power ratio deviation of a specific frequency band in the signal power spectrum. For example, after calculating the signal power spectrum of the reflected signal, the present application can calculate the signal power integral P1 of the 1000Hz~Fs / 2 frequency band, and calculate the signal power integral P0 of the 0~Fs / 2 segment, and finally calculate the current signal power ratio R3 of the 1000Hz~Fs / 2 frequency band and the current power ratio deviation. The calculation formula is as follows:

[0084]

[0085] It is understandable that the vibration spectrum of a bushing in good condition is all in the low-frequency band, and the frequency band above 1000 Hz is relatively small. Therefore, calculating the signal power ratio of the frequency band above 1000 Hz can be used to evaluate the tightness of the wire outlet device at the head of the bushing.

[0086] In one embodiment, before determining the current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range in S130, the following steps may also be included:

[0087] The reflected signal is aligned with the load current signal so that a phase angle of the load current signal is 0°.

[0088] In this embodiment, before determining the current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device within the target load rate range, the reflected signal and the load current signal can be aligned so that the phase angle of the load current signal is 0°.

[0089] Specifically, after receiving the reflected signal and the load current signal, the present application can first shift the load current signal to zero phase angle, and then synchronously shift the reflected signal according to the shifted phase of the load current signal, so that the reflected signal can be aligned with the load current signal.

[0090] In one embodiment, S140 compares the current feature value corresponding to each feature with the historical feature value, and evaluates the fastening state of the transformer bushing head outlet device based on the comparison result, which may include:

[0091] S141: After comparing the current feature value corresponding to each feature with the historical feature value, the feature increment of each feature is determined.

[0092] S142: Determine whether the feature increment of each feature exceeds the preset increment threshold of each feature.

[0093] S143: If the feature increments of all features exceed their respective preset increment thresholds, it is determined that the fastening state of the transformer bushing head outlet device is an abnormal state.

[0094] S144: If the feature increment of at least one feature does not exceed the corresponding preset increment threshold, it is determined that the fastening state of the transformer bushing head outlet device is normal.

[0095] In this embodiment, when comparing the current feature value corresponding to each feature with the historical feature value, the feature increment of each feature can be determined first, and then it can be determined whether the feature increment of each feature exceeds the preset increment threshold of each feature. If the feature increments of all features exceed their respective preset increment thresholds, it is determined that the tightening state of the transformer bushing head outlet device is abnormal. If the feature increment of at least one feature does not exceed the corresponding preset increment threshold, it is determined that the tightening state of the transformer bushing head outlet device is normal.

[0096] Specifically, after obtaining the current amplitude response, current amplitude response deviation, current phase response, current phase response deviation, and current signal power ratio and current power ratio deviation, the present application can obtain the historical amplitude response, historical amplitude response deviation, historical phase response, historical phase response deviation, and historical signal power ratio and historical power ratio deviation under the same target load rate range for two consecutive days. In this way, after taking the difference, the characteristic increments of the current amplitude response, current amplitude response deviation, current phase response, current phase response deviation, and current signal power ratio and current power ratio deviation can be obtained. Then, the present application can determine whether each characteristic increment changes within the respective preset increment threshold range over time. If so, the tightness state of the transformer bushing head outlet device is diagnosed as normal. When at least one characteristic increment exceeds the corresponding preset increment threshold range over time, the tightness state of the transformer bushing head outlet device is diagnosed as abnormal, indicating that there are signs of looseness at the connection, and a reminder indication can be given at this time.

[0097] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0098] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referenced to each other.

[0099] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the tightness status of a transformer bushing head outlet device, applied to a monitoring system for the tightness status of a transformer bushing head outlet device, characterized in that: The system includes: a radar reflector, a millimeter wave radar radio frequency transmitting device, a data acquisition device, and a fastening state evaluation device; The radar reflector is fixedly connected to the bushing head outlet device of the transformer; The millimeter wave radar radio frequency transmitting device is used to transmit a signal to the radar reflector and receive a reflected signal from the radar reflector; The data acquisition device is used to synchronously acquire the reflection signal of the radar reflector received by the millimeter-wave radar radio frequency transmitting device and the load current signal of the transformer, and send the acquired reflection signal and load current signal to the fastening state evaluation device; The fastening state evaluation device is used to obtain the rated load current of the transformer, the reflected signal currently collected by the data acquisition device, and the load current signal of the transformer; Calculating a target load rate according to the rated load current of the transformer and the load current signal, and determining a target load rate interval within which the target load rate lies; Determining current feature values corresponding to different features of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range, and obtaining historical feature values corresponding to corresponding features in the target load rate range within a preset historical period; Compare the current feature value corresponding to each feature with the historical feature value, and evaluate the tightness of the transformer bushing head outlet device based on the comparison results; Characteristics of the reflected signal and the load current signal affecting the tightening state of the transformer bushing head outlet device in the target load rate range include amplitude response, phase response, signal power proportion in a specific frequency band, and respective relative standard deviations; The determining of current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range includes: determining a first amplitude and a first phase of the reflected signal at a first specific frequency, and a second amplitude and a second phase of the load current signal at a second specific frequency, and calculating a current amplitude response and a current amplitude response deviation based on the first amplitude and the second amplitude, and calculating a current phase response and a current phase response deviation based on the first phase and the second phase; wherein the first specific frequency is twice the second specific frequency; Calculate the signal power spectrum of the reflected signal, and determine the current signal power ratio and the current signal power ratio deviation of a specific frequency band in the signal power spectrum, wherein the specific frequency band is a frequency band above 1000 Hz.

2. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1, characterized in that: The radar reflector adopts an angle emitter; The corner emitter is a random shape formed by a polished stainless steel surface.

3. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 2, characterized in that: Each corner of the corner emitter is chamfered to reduce the electric field intensity at each corner.

4. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1, characterized in that: The data acquisition device acquires the reflected signal of the radar reflector and the load current signal of the transformer received by the millimeter-wave radar radio frequency transmitting device according to a preset data sampling rate; Wherein, the preset data sampling rate is not less than 4kHz.

5. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1 or 4, characterized in that: When collecting the load current signal of the transformer, the data collection device collects the load current signal through the transformer bushing current transformer or the current transformer on the transformer bus.

6. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1, characterized in that: Determining the target load rate interval in which the target load rate falls includes: Divide the transformer load rate into multiple load rate intervals according to a preset interval division method; The target load rate is compared with each load rate interval to determine the target load rate interval in which the target load rate is located.

7. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1, characterized in that: Before determining current characteristic values corresponding to different characteristics of the reflected signal and the load current signal that affect the tightening state of the transformer bushing head outlet device in the target load rate range, the method further includes: The reflected signal is aligned with the load current signal so that a phase angle of the load current signal is 0°.

8. The method for evaluating the fastening status of the transformer bushing head outlet device according to claim 1, characterized in that: The comparing the current characteristic value corresponding to each characteristic with the historical characteristic value, and evaluating the fastening state of the transformer bushing head outlet device according to the comparison result, includes: After comparing the current feature value of each feature with the historical feature value, the feature increment of each feature is determined; Determine whether the feature increment of each feature exceeds the preset increment threshold of each feature; If the feature increments of all features exceed their respective preset increment thresholds, it is determined that the fastening state of the transformer bushing head outlet device is abnormal; If the feature increment of at least one feature does not exceed the corresponding preset increment threshold, it is determined that the fastening state of the transformer bushing head outlet device is normal.

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