Dry-type transformer fault detection device and system

Abstract

The invention provides a dry-type transformer fault detection device and system, and the device comprises a signal collection and separation unit which is used for collecting a vibration signal of a transformer through a preset sensor, splitting the collected vibration signal into a low-frequency vibration signal and a high-frequency ultrasonic signal, and outputting a broadband vibration signal; the signal transmission unit is respectively connected with the signal acquisition and separation unit and the data processing unit through a wireless network and is used for processing the broadband vibration signals output by the signal acquisition and separation unit; and the data processing unit is used for processing the received voltage signal through a preset fault detection program so as to realize fault identification and control interaction. According to the invention, the measuring terminal can autonomously establish a WiFi signal, controllable wireless data transmission without external network connection is realized, and the convenience of installation and use is improved. And the upper computer sends an instruction through an encrypted point-to-point link, so that accurate start-stop control of the measurement terminal is realized, and long-term operation power consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer fault detection, in particular to a dry-type transformer fault detection device and system. BACKGROUND

[0002] As an important equipment for power transmission and voltage conversion in power distribution system, the safe and stable operation of the dry-type transformer is of great significance to the power system. It is crucial to conduct real-time mechanical and electrical state online monitoring of the dry-type transformer and to conduct early warning and detection and identification of its faults.

[0003] After long-term operation of the transformer, mechanical defects such as winding and core loosening and insulation defects such as floating discharge and sharp discharge may occur inside the transformer. With the continuous development of random electrical defects, the vibration of the transformer is affected, and partial discharge signals are generated due to internal insulation deterioration. A patch sensor can be used on the surface of the transformer to measure the broadband vibration signals composed of low-frequency signals from mechanical vibration and ultrasonic signals generated by partial discharge.

[0004] The existing online detection system for measuring and analyzing the broadband vibration signals of the transformer mainly includes two design types. One is to set two detection devices specifically, which may lead to a complex overall structure of the measuring device. The other is to use a single composite sensor to collect and process the broadband vibration signals, which can reduce the structure of the device and is easy to install. However, the existing design often highly depends on special equipment such as acquisition cards, which has high cost and is difficult to deploy. The measuring terminal (lower computer) and the upper computer are often difficult to be independent of wired connection or external WiFi connection, which limits the use in infrastructure-free environments. In addition, the upper computer often does not have control over the measuring device, but only has information receiving and processing functions, so that the measuring device continues to work in the measurement state, which increases power consumption and also increases the maintenance frequency of the device for battery-powered designs. The existing broadband vibration signal measurement on the surface of the transformer and the corresponding mechanical and insulation state detection technology highly depend on acquisition cards or external WiFi for signal collection, which is costly and requires additional software environment for control. In terms of fault diagnosis, only a few seconds of vibration state information can achieve good insulation and mechanical fault recognition effect. However, in the existing design, the upper computer often only plays a signal receiving role and does not have a control function. The signal collection often runs continuously, which has high power consumption, shortens the battery working time and increases the maintenance frequency. SUMMARY

[0005] The present application relates to the technical field of transformer fault detection, in particular to a dry-type transformer fault detection device and system.

[0006] In one aspect, a dry-type transformer fault detection device is provided, comprising:

[0007] a signal acquisition and separation unit for acquiring vibration signals of the transformer through a preset sensor, and splitting the acquired vibration signals into low-frequency vibration signals and high-frequency ultrasonic signals, and outputting wideband vibration signals recognizable by a signal transmission unit;

[0008] a signal transmission unit for connecting the signal acquisition and separation unit and the data processing unit through a wireless network, and processing the wideband vibration signals output by the signal acquisition and separation unit to output voltage signals recognizable by the data processing unit;

[0009] a data processing unit for processing the received voltage signals through a preset fault detection program to realize fault recognition and control interaction.

[0010] Preferably, the signal acquisition and separation unit at least includes a voltage amplification module, a voltage follower and a detection circuit;

[0011] The voltage amplification module is used to amplify the received wideband vibration signals and voltage bias the vibration signals with a frequency lower than a preset threshold;

[0012] The voltage follower is used to convert ultrasonic signals within a preset frequency range into direct current envelope signals within a preset voltage range, and reduce the sampling rate requirement of vibration signals for partial discharge monitoring;

[0013] The detection circuit is used to detect the vibration signals and output positive voltage signals.

[0014] Preferably, the signal transmission unit at least includes an analog-to-digital converter and a WiFi module;

[0015] The analog-to-digital converter is used to convert the received wideband vibration signals and establish a corresponding WiFi signal connected with the data processing unit;

[0016] The WiFi module is used to establish a transmission channel based on the transmission control protocol to package and send the wideband vibration signals.

[0017] Preferably, the signal transmission unit is specifically used to start an autonomous networking mode based on a preset network name and password, establish a WiFi signal and a TCP server, and wait for the connection of the data processing unit.

[0018] When the data processing unit connects to the network and establishes a TCP connection, it enters a standby state and does not send data except for connection monitoring.

[0019] Preferably, the signal transmission unit is further configured to, after the data processing unit sends the data segment with the specific accompanying measurement time, identify the instruction requirement contained therein, start the measurement of the analog-to-digital converter, and transmit the data in real time, stop the collection after the measurement is completed, and re-enter the standby state.

[0020] Preferably, the preset sensor at least includes a broadband vibration signal sensor configured to collect vibration signals within a preset frequency range and obtain a corresponding frequency response curve.

[0021] In another aspect, a dry-type transformer fault detection system is also provided, which uses the detection device to check the dry-type transformer fault.

[0022] In summary, the embodiment of the present application has the following beneficial effects:

[0023] The dry-type transformer fault detection device and system provided by the present application can realize wireless transmission of measurement data without relying on external network environment, has a simple and clear structure, realizes miniaturization and integration of the measurement device, and can control the sensor measurement time, reduce operating power consumption, and prolong operating time. The measurement terminal can establish a WiFi signal autonomously, realize controllable wireless data transmission without external network connection, and improve installation and use convenience. The host computer sends instructions through an encrypted point-to-point link to realize precise start-stop control of the measurement terminal and reduce long-term operating power consumption. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without creative labor.

[0025] Figure 1 FIG. 1 is a schematic diagram of a dry-type transformer fault detection device according to an embodiment of the present application.

[0026] Figure 2 FIG. 2 is a schematic diagram of the working process of the signal transmission unit according to an embodiment of the present application.

[0027] Figure 3 FIG. 3 is a schematic diagram of the working process of the data processing unit according to an embodiment of the present application.

[0028] Figure 4 FIG. 4 is a schematic diagram of the working process of the data processing unit according to an embodiment of the present application.

[0029] Figure 5 FIG. 5 is a schematic diagram of the working process of the data processing unit according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.

[0031] As shown in FIG. 1, it is a schematic diagram of an embodiment of the dry-type transformer fault detection device provided by the present application. In this embodiment, it comprises: Figure 1

[0032] The signal acquisition and separation unit is used for acquiring the vibration signal of the transformer through a preset sensor, and separates the acquired vibration signal into a low-frequency vibration signal and a high-frequency ultrasonic signal, and outputs a wide-frequency vibration signal that can be recognized by the signal transmission unit; in the normal working state of the transformer, the core and winding will produce forced vibration under magnetostriction and Maxwell stress, and the vibration frequency is usually below 20 kHz. When internal partial discharge occurs, corresponding ultrasonic signals will also be generated inside. Therefore, a wide-frequency vibration signal can be measured on the surface of the transformer, which can be directly measured by a single composite sensor, or a vibration sensor and an ultrasonic sensor can be used for measurement respectively. The acquisition and separation unit includes a signal conditioning and power supply circuit, which is responsible for providing 24V DC voltage power supply for the sensor, and receiving the wide-frequency vibration signal measured by the sensor. The measured signal is amplified by an operational amplifier, and separated by a plurality of Sallen-Key second-order low-pass and high-pass filters, and finally separated into a low-frequency vibration signal and a high-frequency ultrasonic signal. The amplification factor of the amplification circuit can be adjusted so that the signal amplitude reaching the single-chip microcomputer is as close to 3.3V as possible. The low-frequency signal uses a voltage bias circuit to provide a positive voltage bias of 1.65V, and the high-frequency signal is output to the two ADC pins of the single-chip microcomputer through a detection circuit, respectively.

[0033] ​A signal transmission unit is configured to connect the signal collection and separation unit and the data processing unit via a wireless network, process the broadband vibration signal output by the signal collection and separation unit, and output a voltage signal recognizable by the data processing unit. A single-chip microcomputer supporting a dual-channel ADC and a WiFi module is selected to read the processed broadband vibration signal via an ADC interface, establish a WiFi signal for connection by the upper computer, and establish a TCP-based transmission channel to package and send the measurement data. The single-chip microcomputer should have a non-volatile memory to adapt to the working state that may be powered off at any time. Two sampling precisions of up to 12 bits are provided, and the sampling rate of each channel is set to 20 kHz. In actual use, the two channels take turns to read two data and transfer them to the cache area. When the cache area reaches the specified capacity, the cache area data is sent to the upper computer and then emptied, realizing the stream transmission of data and reducing the memory occupation.

[0034] A data processing unit is configured to process the received voltage signal via a preset fault detection program to realize fault recognition and control interaction. The upper computer data processing unit is responsible for receiving the signal collected and sent by the dual-ADC channel of the single-chip microcomputer and performing subsequent data processing. Based on a general programming environment, the upper computer program can be developed to establish TCP network communication with the single-chip microcomputer, thereby realizing work control and data interaction. Through trigger-type collection based on TCP instructions, the continuous running power consumption can be greatly reduced. As a TCP server, the single-chip microcomputer interacts with the upper computer. The overall working process is shown in Figure 3 The software can receive the broadband vibration signal collected by the single-chip microcomputer or read the historical data file, and judge the insulation and mechanical state of the transformer based on the data.

[0035] In the specific embodiment of the present application, the signal acquisition and separation unit at least comprises a voltage amplification module, a voltage follower and a detection circuit; the voltage amplification module is used to amplify the received broadband vibration signal and voltage bias the vibration signal with a frequency lower than a preset threshold; the voltage follower is used to convert the ultrasonic signal in a preset frequency range into a direct current envelope signal in a preset voltage range, and reduce the sampling rate requirement of the vibration signal for partial discharge monitoring; and the detection circuit is used to detect the vibration signal and output a positive voltage signal. For a single-chip microcomputer, the ADC (Analog-to-Digital Converter) sampling rate is often in the range of several thousand to tens of thousands, and the voltage acquisition range is often between 0-3.3V. For a vibration signal, the signal output is positive and negative, and the frequency range of an ultrasonic signal is between 20kHz-500kHz. In addition, the amplitudes of both are often extremely low, so they cannot be directly collected by a single-chip microcomputer. Therefore, the acquisition unit should include a voltage amplification, a voltage follower and a detection circuit (composed of an operational amplifier and a diode). The received signal is amplified, and voltage bias is provided for low-frequency vibration signals for single-chip microcomputer measurement; 20-500kHz ultrasonic signals are converted into 0-3.3V direct current envelope signals, reducing the sampling rate requirement of high-frequency signals for partial discharge monitoring. The output of the high-frequency signal through the detection circuit is a positive voltage, and no additional circuit is needed to provide voltage bias.

[0036] The signal transmission unit at least comprises an analog-to-digital converter and a WiFi module; the analog-to-digital converter is used to convert the received broadband vibration signal, and establish a corresponding WiFi signal and data processing unit connection; and the WiFi module is used to establish a transmission channel based on the transmission control protocol to package and send the broadband vibration signal. The signal transmission unit is specifically used to start the autonomous networking mode based on the preset network name and password, establish a WiFi signal and TCP server, and wait for the connection of the data processing unit; when the data processing unit connects to the network and establishes a TCP connection, it enters a standby state and does not send data except for connection monitoring. After the data processing unit sends a data segment with a specific attached measurement time, the instruction requirement contained therein is identified, the analog-to-digital converter measurement is started, and the data is transmitted in real time. After the measurement is completed, the collection is stopped, and the standby state is re-entered. For example Figure 2As shown, after power-on, the ADC and WiFi are initialized. Based on the network name and password pre-installed in the microcontroller, it initiates autonomous networking mode, establishes a WiFi signal and TCP server, and waits for the host computer to connect. After the host computer connects to the network and establishes the TCP connection, it enters standby mode, and does not send data except for connection monitoring. After the host computer sends a data segment with a specific measurement time, it identifies the instruction requirements contained therein, starts ADC measurement, and transmits data in real time. After the measurement is completed, it stops data acquisition and returns to standby mode. Thus, the measurement terminal can autonomously establish a WiFi hotspot based on the microcontroller, realizing point-to-point transmission in a network-free environment.

[0037] In a specific embodiment, the preset sensor includes at least a broadband vibration signal sensor, which collects vibration signals within a preset frequency range to obtain the corresponding frequency response curve. The broadband vibration signal sensor can be a single piezoelectric composite sensor, or a single sensor can be used, with vibration / ultrasonic sensors extracting portions of the broadband vibration signal separately. In this example, a broadband vibration sensor is used for measurement, exhibiting a relatively flat frequency response curve within the 10Hz-200kHz range. It is an IEPE (Integrated Electronics Piezo-Electric) sensor powered by a constant current.

[0038] In one specific embodiment, after the measuring terminal is powered on, it will automatically establish a WiFi network signal named "ESP32_AP" with the password "12345678". Both can be changed arbitrarily before the microcontroller is programmed. After the host computer connects, it will obtain a preset IP address, 192.168.4.2. After confirming the network connection, the ESP32 will attempt to establish communication with the device at this IP address. After the host computer connects to WiFi, it can directly listen to port 8080 at IP address 0.0.0.0 to establish TCP communication. After establishing communication, the host computer sets the acquisition time and clicks the "Start Acquisition" button to send a TCP command carrying time parameters, thereby controlling the measuring terminal to run and read the broadband vibration status information at the set time. In addition, in the unit settings on the settings page, the amplitude of the input data can be restored according to the amplification factor set in step 2. For testing transformer loosening and partial discharge, the measured separated broadband vibration signal data is as follows: Figure 4 As shown in the figure. The host computer can extract vibration signal features (such as the fundamental frequency amplitude ratio) and combine them with industry-standard fault models to achieve condition assessment, thereby further analyzing the insulation and mechanical condition. In this use case, FFT-based and V-PRPD spectral methods are integrated for insulation / mechanical condition analysis, and the results are shown in the figure. Figure 5 As shown.

[0039] As can be seen, this device enables the measuring terminal to autonomously establish a WiFi signal, thereby achieving controllable wireless data transmission without the need for an external network connection, improving the convenience of installation and use. The host computer program design allows for accurate tracking and control of the measuring terminal's operating status, reducing power consumption. It has achieved good results in identifying the operating status of transformers, demonstrating the stability and accuracy of the current design during long-term data acquisition and transmission.

[0040] An embodiment of the present invention also provides a fault detection system for dry-type transformers, which uses the aforementioned detection device to inspect for faults in dry-type transformers.

[0041] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0042] The dry-type transformer fault detection device and system provided by this invention enables wireless transmission of measurement data without relying on an external network environment; its simple and clear structure achieves miniaturization and integration of the measurement device; the sensor measurement time is controllable, reducing operating power consumption and increasing operating time. It allows the measurement terminal to autonomously establish a WiFi signal, achieving controllable wireless data transmission without external network connection, improving the convenience of installation and use. The host computer sends commands through an encrypted point-to-point link, enabling precise start and stop control of the measurement terminal and reducing long-term operating power consumption.

[0043] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A fault detection device for a dry-type transformer, characterized in that, include: The signal acquisition and separation unit is used to acquire the vibration signal of the transformer through a preset sensor, and to split the acquired vibration signal into a low-frequency vibration signal and a high-frequency ultrasonic signal, and output a wideband vibration signal that can be recognized by the signal transmission unit. The signal transmission unit is used to connect to the signal acquisition and separation unit and the data processing unit via a wireless network, and to process the broadband vibration signal output by the signal acquisition and separation unit to output a voltage signal that can be recognized by the data processing unit. The data processing unit is used to process the received voltage signal through a preset fault detection program to realize fault identification and control interaction.

2. The detection device as described in claim 1, characterized in that, The signal acquisition and separation unit includes at least a voltage amplification module, a voltage follower, and a detection circuit; The voltage amplification module is used to amplify the received broadband vibration signal and apply voltage bias to vibration signals with frequencies below a preset threshold. The voltage follower is used to convert ultrasonic signals within a preset frequency range into DC envelope signals within a preset voltage range, and to reduce the sampling rate requirement of vibration signals used for partial discharge monitoring. The detection circuit is used to detect the vibration signal and output a positive voltage signal.

3. The detection device as described in claim 2, characterized in that, The signal transmission unit includes at least an analog-to-digital converter and a WiFi module; The analog-to-digital converter is used to convert the received broadband vibration signal and establish a corresponding WiFi signal to connect with the data processing unit. The WiFi module is used to establish a transmission channel based on the transmission control protocol to package and send broadband vibration signals.

4. The detection device as described in claim 3, characterized in that, The signal transmission unit is specifically used to initiate an autonomous networking mode based on a preset network name and password, establish a WiFi signal and TCP server, and wait for the data processing unit to connect. Once the data processing unit connects to the network and establishes a TCP connection, it enters a standby state and does not send data except for connection monitoring.

5. The detection device as described in claim 4, characterized in that, The signal transmission unit is also used to identify the instruction requirements contained therein after the data processing unit sends a data segment with a specific measurement time, start the analog-to-digital converter measurement, transmit the data in real time, stop the acquisition after the measurement is completed, and return to the standby state.

6. The detection device as described in claim 1, characterized in that, The preset sensor includes at least a wideband vibration signal sensor, which collects vibration signals within a preset frequency range to obtain the corresponding frequency response curve.

7. A fault detection system for dry-type transformers, characterized in that, The faults of dry-type transformers are inspected using the detection device as described in any one of claims 1-6.

Images