Transformer internal temperature detection system

Abstract

The invention discloses a transformer internal temperature detection system, and relates to a device for measuring temperature by using the change in an optical fiber. In order to overcome the problem that the measurement error is large because the measurement of the internal temperature of the existing power transformer is easily interfered by a magnetic field, the device comprises at least one fiber bragg grating temperature sensor, a demodulation module, a signal processing module and a metal shielding cover, the fiber grating temperature sensor is used for detecting the temperature in the transformer; the demodulation module is used for receiving a grating reflection light signal output from the emitting end of the fiber grating temperature sensor and demodulating the grating reflection light signal into a demodulation electric signal; the signal processing module is used for obtaining a transformer internal temperature measurement value according to the demodulation electric signal; the metal shielding cover covers the light source module and the demodulation module.

Description

Technical Field

[0001] The present invention relates to an apparatus for measuring temperature using changes in an optical fiber. Background Art

[0002] The temperature of transformer windings not only affects the service life of the transformer, but is also closely related to its safety performance. When the hot spot temperature of the winding exceeds the allowable limit, it will cause the transformer insulation material to age faster, thus shortening the service life of the equipment and possibly causing failures, threatening the safety of the entire power transmission and transformation system. On the contrary, if the hot spot temperature of the winding is too low, it means that the transformer is not working at full load, which means that resources are not fully utilized to a certain extent, thus affecting the economic benefits of the power system.

[0003] The existing internal temperature measurement of power transformers is mainly based on sensor measurement based on electrical signals and sensor measurement based on optical signals. Sensors based on electrical signals, such as resistance thermometers and thermocouples, measure temperature by the change in the resistance of conductors or semiconductors with temperature, but such sensors are easily affected by the strong electromagnetic field inside the transformer, resulting in large errors in the measurement results. Sensors based on optical signals include infrared temperature sensors, which calculate the temperature by detecting the intensity of infrared radiation emitted by objects, but in the complex electromagnetic environment of power transformers, the propagation of infrared rays is also easily disturbed, especially in the presence of dust or other obstructions, which will also affect the measurement accuracy. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem that the measurement of the internal temperature of the existing power transformer is easily disturbed by the magnetic field, resulting in large measurement errors, and provide a transformer internal temperature detection system.

[0005] The transformer internal temperature detection system of the present invention comprises at least one fiber grating temperature sensor, a demodulation module, a signal processing module and a metal shielding cover;

[0006] Fiber Bragg grating temperature sensor is used to detect the temperature inside the transformer;

[0007] The demodulation module is used to receive the grating reflected light signal output from the output end of the fiber grating temperature sensor, and demodulate the grating reflected light signal into a demodulation electrical signal;

[0008] The signal processing module is used to obtain the internal temperature measurement value of the transformer according to the demodulated electrical signal;

[0009] The metal shielding cover is arranged outside the light source module and the demodulation module.

[0010] Furthermore, it also includes a monitoring alarm module;

[0011] The monitoring alarm module is also used to compare the transformer internal temperature measurement value with the preset transformer internal temperature maximum threshold and transformer internal temperature minimum threshold; and generate a high temperature alarm message when the transformer internal temperature measurement value is greater than the transformer internal temperature maximum threshold, and generate a low temperature alarm message when the transformer internal temperature measurement value is less than the transformer internal temperature minimum threshold.

[0012] Further, a low-pass filter is included;

[0013] The low-pass filter is used to filter the demodulated electrical signal and send the filtered demodulated electrical signal to the signal processing module.

[0014] Further, it also includes a first self-diagnosis module;

[0015] The first self-diagnosis module is used to receive the grating reflected light signal;

[0016] and detecting the intensity of the grating reflected light signal, and comparing the intensity of the grating reflected light signal with a preset grating reflected light signal intensity threshold, and if the intensity of the grating reflected light signal is less than the grating reflected light signal intensity threshold, determining that the fiber Bragg grating temperature sensor is abnormal;

[0017] The temperature response time is calculated and compared with the response time threshold range. If the temperature response time exceeds the response time threshold range, the fiber Bragg grating temperature sensor is judged to be abnormal. The temperature response time is the time for the wavelength of the grating reflected light signal to change before and after the temperature change.

[0018] Furthermore, it also includes a light source module and a second self-diagnosis module;

[0019] The light source module is used to generate a broadband optical signal and transmit it from the incident end of the fiber Bragg grating temperature sensor to the inside of the fiber Bragg grating temperature sensor;

[0020] The second self-diagnosis module is used to receive the broadband optical signal;

[0021] and measuring the optical power of the broadband optical signal, and comparing the optical power of the broadband optical signal with a preset optical power threshold, and if the optical power of the broadband optical signal is less than the optical power threshold, determining that the light source module is abnormal;

[0022] And multiple optical powers are measured multiple times within a set time, the optical power standard deviation of the multiple optical powers is calculated, and the optical power standard deviation is compared with a preset standard deviation threshold. If the optical power standard deviation is greater than the standard deviation threshold, the light source module is determined to be abnormal.

[0023] Further, it also includes a third self-diagnosis module;

[0024] The third self-diagnosis module is used to input the pre-stored reference optical signal into the demodulation module;

[0025] The reference light signal is a grating reflected light signal corresponding to a calibrated temperature value;

[0026] And obtain the reference temperature value obtained by demodulating and processing the reference light signal from the signal processing module, and compare the reference temperature value with the calibration temperature value. If the difference between the reference temperature value and the calibration temperature value exceeds the preset temperature demodulation accuracy error, the demodulation module is determined to be abnormal.

[0027] And the processing time from inputting the reference light signal into the demodulation module to obtaining the reference temperature value is recorded. If the processing time exceeds a preset time threshold, it is determined that the demodulation module is abnormal.

[0028] Further, it also includes a fourth self-diagnosis module;

[0029] The fourth self-diagnosis module is used to input the standard temperature data into the signal processing module;

[0030] And obtain the processed temperature data obtained by processing the standard temperature data from the signal processing module, and compare the processed temperature data with the standard temperature data. If the difference between the processed temperature data and the standard temperature data exceeds a preset data processing error, the signal processing module is determined to be abnormal.

[0031] Further, a fifth self-diagnosis module is included;

[0032] The fifth self-diagnosis module user inputs the first alarm test temperature value and the second alarm test temperature value to the monitoring alarm module, and records the input time of the first alarm test temperature value and the second alarm test temperature value respectively;

[0033] The first alarm temperature test value is greater than the maximum threshold of the transformer internal temperature, and the second alarm temperature test value is less than the minimum threshold of the transformer internal temperature;

[0034] and obtaining high temperature alarm information and the output time of the high temperature alarm information from the monitoring alarm module; if the high temperature alarm information cannot be obtained, or the low temperature alarm information is obtained, or the output time of the high temperature alarm information exceeds the preset time difference of the input time of the first alarm test temperature value, the monitoring alarm module is determined to be abnormal;

[0035] And obtain the low temperature alarm information and the output time of the low temperature alarm information from the monitoring alarm module; if the low temperature alarm information cannot be obtained, or the high temperature alarm information is obtained, or the output time of the low temperature alarm information exceeds the preset time difference of the input time of the second alarm test temperature value, the monitoring alarm module is determined to be abnormal.

[0036] Furthermore, it also includes a data storage module;

[0037] The data storage module is used to store the detection system information;

[0038] The detection system information includes storing the transformer internal temperature measurement value, high temperature alarm information and low temperature alarm information.

[0039] Furthermore, it also includes a wireless transmission module;

[0040] The data storage module is also used to transmit the detection system information to the host computer through the wireless transmission module.

[0041] The beneficial effects of the present invention are:

[0042] The transformer internal temperature detection system of the present invention includes a fiber grating temperature sensor for temperature detection. The fiber grating temperature sensor uses Bragg wavelength shift to detect temperature changes and has the advantage of not being subject to electromagnetic interference. The metal shield effectively reduces the penetration of the electromagnetic field and improves the ability to be interfered by the electromagnetic field. The influence of the external electromagnetic field on the sensor can be further reduced, making the measurement data more accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the transformer internal temperature detection system of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0046] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention. Specific implementation method 1

[0048] The transformer internal temperature detection system of this embodiment includes at least one fiber grating temperature sensor 1, a demodulation module 3, a signal processing module 4 and a metal shielding cover 5;

[0049] The fiber grating temperature sensor 1 is used to detect the temperature inside the transformer;

[0050] The demodulation module 3 is used to receive the grating reflected light signal output from the output end of the fiber grating temperature sensor 1, and demodulate the grating reflected light signal into a demodulation electrical signal;

[0051] The signal processing module 4 is used to obtain the internal temperature measurement value of the transformer according to the demodulated electrical signal;

[0052] The metal shielding cover 5 is disposed outside the light source module 2 and the demodulation module 3 .

[0053] Specifically, the fiber grating temperature sensor 1 is responsible for sensing the temperature change inside the transformer.

[0054] The fiber Bragg grating temperature sensor 1 reflects the change of temperature through the change of the reflection wavelength of the Bragg grating.

[0055] The fiber grating temperature sensor 1 is installed at the position of the iron core inside the transformer, wherein the installation position of the fiber grating temperature sensor 1 needs to take into account the hot spot area and winding distribution of the transformer to accurately measure the temperature.

[0056] The light source module 2 is responsible for providing a broadband light source for irradiating the fiber grating temperature sensor 1 .

[0057] The demodulation module 3 is used to demodulate the optical signal reflected by the fiber grating temperature sensor 1 and convert it into an electrical signal.

[0058] The signal processing module 4 is responsible for processing and analyzing the demodulated electrical signal and extracting the temperature information; and transmitting it to the data storage module 9 for storage.

[0059] The light source module 2 is connected to the fiber Bragg grating temperature sensor 1 via an optical fiber. The light source module 2 is installed close to the fiber Bragg grating temperature sensor 1 to ensure that the light emitted by the light source can be effectively transmitted to the fiber Bragg grating temperature sensor 1 .

[0060] The fiber grating temperature sensor 1 and the demodulation module 3 are covered by the metal shielding cover 5, which can effectively reduce the penetration of the electromagnetic field, thereby improving the ability to avoid interference by the electromagnetic field. Specific implementation method 2

[0062] This embodiment is a further explanation of the first embodiment. In this embodiment, a monitoring alarm module 6 is also included;

[0063] The monitoring alarm module 6 is also used to compare the transformer internal temperature measurement value with the preset transformer internal temperature maximum threshold and transformer internal temperature minimum threshold; and generate a high temperature alarm message when the transformer internal temperature measurement value is greater than the transformer internal temperature maximum threshold, and generate a low temperature alarm message when the transformer internal temperature measurement value is less than the transformer internal temperature minimum threshold.

[0064] The other technical features of this embodiment are exactly the same as those of the first embodiment.

[0065] Specifically, the monitoring alarm module 6 is responsible for real-time monitoring of the temperature changes inside the transformer and sending out an alarm signal when the temperature exceeds a set threshold, which can effectively remind the operator to take corresponding measures.

[0066] The monitoring and alarm module 6 is connected to the demodulation module 3 and the signal processing module 4, and receives the demodulated temperature signal in real time. The monitoring and alarm module 6 obtains temperature data through the data structure, which is convenient for the operator to observe the temperature changes inside the transformer in real time. The operator sets the temperature threshold in the monitoring and alarm module 6 based on the working requirements and safety standards of the transformer. The monitoring and alarm module 6 records the alarm occurrence time, temperature value and alarm type, where the alarm type includes temperature exceeding (high temperature alarm information) and temperature below the threshold (low temperature alarm information). Specific implementation method three

[0068] This embodiment is a further description of the first or second embodiment. In this embodiment, a low-pass filter 7 is further included.

[0069] The low-pass filter 7 is used to filter the demodulated electrical signal and send the filtered demodulated electrical signal to the signal processing module 4 .

[0070] The other technical features of this embodiment are exactly the same as those of embodiment one or two.

[0071] Specifically, the low-pass filter 7 is used to filter out high-frequency noise and interference in the output signal of the demodulation module 3, thereby effectively improving the ability to avoid interference by electromagnetic fields.

[0072] The low-pass filter 7 selects a passive filter, which has the advantages of simple structure, low cost and high operational reliability. The filter circuit composed of a combination of inductance, capacitance and resistance can filter out one or more harmonics. The most common and easy-to-use passive filter structure is to connect the inductor and the capacitor in series.

[0073] The low-pass filter 7 is installed behind the demodulation module 3 and before the signal processing module 4. The input port of the low-pass filter 7 is directly connected to the output port of the demodulation module 3 using a wire or cable, and the output port of the low-pass filter 7 is directly connected to the input port of the signal processing module 4, which can effectively improve the quality and stability of the signal.

[0074] The above-mentioned fiber Bragg grating temperature sensor 1 is connected to the demodulation module 3 through the optical fiber, the demodulation module 3 is connected to the signal processing module 4 through the optical fiber, the signal processing module 4 is connected to the data storage module 9 through the optical fiber, and the signal processing module 4 is connected to the monitoring alarm module 6 through the optical fiber. The modules are connected in series through the optical fiber until the temperature data is transmitted to the monitoring alarm module 6. When performing temperature detection, as the internal temperature of the transformer changes, the reflection wavelength of the fiber Bragg grating temperature sensor 1 will change accordingly. The demodulation module 3 determines the temperature change by detecting the change in the reflection wavelength, and transmits the temperature information to the signal processing module 4 for processing and analysis. It can detect the temperature change inside the transformer in real time and accurately, providing important guarantee for the safe operation of the transformer. Specific implementation method four

[0076] This embodiment is a further explanation of the third embodiment. In this embodiment, a first self-diagnosis module 8-1 is further included;

[0077] The first self-diagnosis module 8-1 is used to receive the grating reflected light signal;

[0078] and detecting the intensity of the grating reflected light signal, and comparing the intensity of the grating reflected light signal with a preset grating reflected light signal intensity threshold, if the intensity of the grating reflected light signal is less than the grating reflected light signal intensity threshold, determining that the fiber Bragg grating temperature sensor 1 is abnormal;

[0079] The temperature response time is calculated and compared with the response time threshold range. If the temperature response time exceeds the response time threshold range, the fiber grating temperature sensor 1 is determined to be abnormal. The temperature response time is the time for the wavelength of the grating reflected light signal to change before and after the temperature change.

[0080] The other technical features of this embodiment are exactly the same as those of the third embodiment. Specific implementation method five

[0082] This embodiment is a further description of the third embodiment. In this embodiment, a light source module 2 and a second self-diagnosis module 8-2 are further included;

[0083] The light source module 2 is used to generate a broadband optical signal, and transmit it from the incident end of the fiber Bragg grating temperature sensor 1 to the inside of the fiber Bragg grating temperature sensor 1;

[0084] The second self-diagnosis module 8-2 is used to receive broadband optical signals;

[0085] and measuring the optical power of the broadband optical signal, and comparing the optical power of the broadband optical signal with a preset optical power threshold, and if the optical power of the broadband optical signal is less than the optical power threshold, determining that the light source module 2 is abnormal;

[0086] And multiple optical powers are measured multiple times within a set time, the optical power standard deviation of the multiple optical powers is calculated, and the optical power standard deviation is compared with a preset standard deviation threshold. If the optical power standard deviation is greater than the standard deviation threshold, it is determined that the light source module 2 is abnormal.

[0087] The other technical features of this embodiment are exactly the same as those of the third embodiment. Specific implementation method 6

[0089] This embodiment is a further explanation of the third embodiment. In this embodiment, a third self-diagnosis module 8-3 is also included;

[0090] The third self-diagnosis module 8-3 is used to input the pre-stored reference optical signal into the demodulation module 3;

[0091] The reference light signal is a grating reflected light signal corresponding to a calibrated temperature value;

[0092] And obtain the reference temperature value obtained by demodulating and processing the reference light signal from the signal processing module 4, and compare the reference temperature value with the calibration temperature value. If the difference between the reference temperature value and the calibration temperature value exceeds the preset temperature demodulation accuracy error, it is determined that the demodulation module 3 is abnormal.

[0093] And the processing time from inputting the reference light signal into the demodulation module 3 to obtaining the reference temperature value is recorded. If the processing time exceeds a preset time threshold, it is determined that the demodulation module 3 is abnormal.

[0094] The other technical features of this embodiment are exactly the same as those of the third embodiment. Specific implementation method seven

[0096] This embodiment is a further explanation of the third embodiment. In this embodiment, a fourth self-diagnosis module 8-4 is also included.

[0097] The fourth self-diagnosis module 8-4 is used to input the standard temperature data into the signal processing module 4;

[0098] And obtain the processed temperature data obtained by processing the standard temperature data from the signal processing module 4, and compare the processed temperature data with the standard temperature data. If the difference between the processed temperature data and the standard temperature data exceeds the preset data processing error, it is determined that the signal processing module 4 is abnormal.

[0099] The other technical features of this embodiment are exactly the same as those of the third embodiment. Specific implementation method eight

[0101] This embodiment is a further description of the third embodiment. In this embodiment, a fifth self-diagnosis module 8-5 is further included.

[0102] The fifth self-diagnosis module 8-5: the user inputs the first alarm test temperature value and the second alarm test temperature value to the monitoring alarm module 6, and respectively records the input time of the first alarm test temperature value and the second alarm test temperature value;

[0103] The first alarm temperature test value is greater than the maximum threshold of the transformer internal temperature, and the second alarm temperature test value is less than the minimum threshold of the transformer internal temperature;

[0104] and obtaining high temperature alarm information and the output time of the high temperature alarm information from the monitoring alarm module 6; if the high temperature alarm information cannot be obtained, or the low temperature alarm information is obtained, or the output time of the high temperature alarm information exceeds the preset time difference of the input time of the first alarm test temperature value, the monitoring alarm module 6 is determined to be abnormal;

[0105] And obtain the low temperature alarm information and the output time of the low temperature alarm information from the monitoring alarm module 6; if the low temperature alarm information cannot be obtained, or the high temperature alarm information is obtained, or the output time of the low temperature alarm information exceeds the preset time difference of the input time of the second alarm test temperature value, the monitoring alarm module 6 is determined to be abnormal.

[0106] The other technical features of this embodiment are exactly the same as those of the third embodiment.

[0107] Specifically, the self-diagnosis module 8 includes the first self-diagnosis module 8-1 to the fifth self-diagnosis module for diagnosing multiple modules, and is responsible for self-diagnosis of the entire temperature detection system. The self-diagnosis module 8 regularly detects the operating status of the fiber grating temperature sensor 1, the light source module 2, the demodulation module 3, the signal processing module 4, the data storage module 9 and the monitoring alarm module 6 to determine whether there is a hidden fault. If an abnormality is detected, a fault prompt signal is issued in time, and the fault information is transmitted to the data storage module 9 for recording, so that the operator can perform repairs and maintenance in time. The self-diagnosis of the self-diagnosis module 8 includes:

[0108] Signal strength monitoring continuously monitors the intensity of the optical signal reflected by the fiber Bragg grating temperature sensor 1. If the intensity of the optical signal is significantly lower than the normal range, there may be a sensor failure or a problem with the optical fiber connection.

[0109] Response time analysis records the response time of the fiber Bragg grating temperature sensor 1 to temperature changes. Under normal circumstances, the fiber Bragg grating temperature sensor 1 should respond to temperature changes within a certain time range. If the response time is too long or too short, it indicates that the performance of the fiber Bragg grating temperature sensor 1 is abnormal.

[0110] Output power monitoring, the self-diagnosis module 8 determines the working status of the light source module 2 by detecting the light power output by the light source module 2. If the output light power is lower than the set threshold, it may be due to aging, damage or power supply problem of the light source.

[0111] Stability evaluation: Analyze the stability of the light output of the light source module 2. If the light power fluctuates greatly, it may affect the accuracy of temperature detection. The stability is evaluated by measuring the light power multiple times over a period of time and calculating its standard deviation.

[0112] Demodulation detection, the self-diagnosis module 8 inputs the reflected signal of the fiber Bragg grating temperature sensor 1 at a known temperature into the demodulation module 3, and then compares the demodulated temperature value with the actual known temperature. If the error exceeds the allowable range, it means that the demodulation accuracy of the demodulation module 3 has decreased and calibration or maintenance is required.

[0113] Signal processing speed monitoring records the time it takes for the demodulation module 3 to process the optical signal and output temperature information. If the processing speed is significantly slowed down, it indicates that the demodulation module 3 has a performance abnormality.

[0114] Data processing accuracy monitoring, the self-diagnosis module 8 inputs a set of standard temperature data into the signal processing module 4 to check whether the processed results are consistent with expectations.

[0115] Alarm function test: the self-diagnosis module 8 simulates the situation where the temperature exceeds the set threshold value, checks whether the monitoring alarm module 6 can send out an alarm signal in time, and at the same time, checks the accuracy of the alarm type and whether the record of the alarm occurrence time is correct.

[0116] Display function check to ensure that the display screen or indicator light of the monitoring alarm module 6 can normally display temperature information and alarm status. Specific implementation method nine

[0118] This embodiment is a further description of the fourth, fifth, sixth, seventh or eighth embodiment. In this embodiment, a data storage module 9 is further included.

[0119] The data storage module 9 is used to store the detection system information;

[0120] The detection system information includes storing the transformer internal temperature measurement value, high temperature alarm information and low temperature alarm information.

[0121] The other technical features of this embodiment are exactly the same as those of embodiments four, five, six, seven or eight.

[0122] Specifically, the data storage module 9 is responsible for storing all received data, such as the internal temperature measurement value of the transformer detected and the alarm information generated by the monitoring alarm module 6. These data are stored in the data storage module 9 to facilitate subsequent analysis and fault diagnosis.

[0123] During use, the self-diagnosis module 8 is used to:

[0124] Storage capacity detection: the self-diagnosis module 8 regularly detects the remaining storage space of the data storage module 9. If it is close to saturation, an early warning is issued to remind the operator to expand the storage in time.

[0125] Data integrity check, randomly reads stored data to check whether there is any data loss or corruption. Specific implementation method 10

[0127] This embodiment is a further description of the ninth embodiment. In this embodiment, a wireless transmission module 10 is further included.

[0128] The data storage module 9 is also used to transmit the detection system information to the host computer through the wireless transmission module 10.

[0129] The other technical features of this embodiment are exactly the same as those of embodiment nine.

[0130] Specifically, the wireless transmission module 10 is used to transmit the data in the data storage module 9 to the remote monitoring terminal (host computer) in a wireless manner, so as to realize remote real-time monitoring of the internal temperature change of the transformer.

[0131] The transformer internal temperature detection system of the present method, the specific temperature detection steps include:

[0132] S1, the light source module 2 emits a light signal of a specific wavelength, which is transmitted to the fiber grating temperature sensor 1 through the optical fiber. The fiber grating temperature sensor 1 installed inside the transformer is affected by the temperature change, and its grating period changes, resulting in a change in the wavelength of the emitted light;

[0133] S2, after receiving the grating reflected light signal, the demodulation module 3 demodulates it and converts the wavelength change into an electrical signal. The signal processing module 4 amplifies and filters the demodulated electrical signal to improve the quality and stability of the signal;

[0134] S3, low-pass filter 7 filters high-frequency noise and interference, effectively avoiding electromagnetic field penetration interference;

[0135] S4, the signal processing module 4 stores the processed temperature data in the data storage module 9 for subsequent analysis and processing. The monitoring alarm module 6 reads the temperature data in the data storage module 9 in real time and displays it on the monitoring interface. When the temperature exceeds or falls below the set temperature threshold, an alarm signal is issued to notify the operator to perform maintenance.

[0136] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the features of the various dependent claims and herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with the individual embodiments may be used in other embodiments.

Claims

1. Transformer internal temperature detection system, characterized in that: It comprises at least one fiber grating temperature sensor (1), a demodulation module (3), a signal processing module (4) and a metal shielding cover (5); The fiber grating temperature sensor (1) is used to detect the temperature inside the transformer; The demodulation module (3) is used to receive the grating reflected light signal output from the output end of the fiber grating temperature sensor (1), and demodulate the grating reflected light signal into a demodulated electrical signal; The signal processing module (4) is used to obtain a measured value of the internal temperature of the transformer according to the demodulated electrical signal; The metal shielding cover (5) is arranged outside the light source module (2) and the demodulation module (3).

2. The transformer internal temperature detection system according to claim 1, characterized in that: It also includes a monitoring and alarm module (6); The monitoring alarm module (6) is used to compare the transformer internal temperature measurement value with a preset transformer internal temperature maximum threshold value and transformer internal temperature minimum threshold value; and to generate a high temperature alarm message when the transformer internal temperature measurement value is greater than the transformer internal temperature maximum threshold value, and to generate a low temperature alarm message when the transformer internal temperature measurement value is less than the transformer internal temperature minimum threshold value.

3. The transformer internal temperature detection system according to claim 1 or 2, characterized in that: Also includes a low pass filter (7); The low-pass filter (7) is used to filter the demodulated electrical signal and send the filtered demodulated electrical signal to the signal processing module (4).

4. The transformer internal temperature detection system according to claim 3, characterized in that: Also includes a first self-diagnosis module (8-1); The first self-diagnosis module (8-1) is used to receive the grating reflected light signal; and detecting the intensity of the grating reflected light signal, and comparing the intensity of the grating reflected light signal with a preset grating reflected light signal intensity threshold, and if the intensity of the grating reflected light signal is less than the grating reflected light signal intensity threshold, determining that the fiber Bragg grating temperature sensor (1) is abnormal; The temperature response time is calculated and compared with a response time threshold range. If the temperature response time exceeds the response time threshold range, the fiber grating temperature sensor (1) is judged to be abnormal. The temperature response time is the time for the wavelength of the grating reflected light signal to change before and after the temperature change.

5. The transformer internal temperature detection system according to claim 3, characterized in that: It also includes a light source module (2) and a second self-diagnosis module (8-2); The light source module (2) is used to generate a broadband optical signal, and transmit the signal from the incident end of the fiber Bragg grating temperature sensor (1) to the interior of the fiber Bragg grating temperature sensor (1); The second self-diagnosis module (8-2) is used to receive a broadband optical signal; and measuring the optical power of the broadband optical signal, and comparing the optical power of the broadband optical signal with a preset optical power threshold, and if the optical power of the broadband optical signal is less than the optical power threshold, determining that the light source module (2) is abnormal; And multiple optical powers are measured multiple times within a set time, the optical power standard deviation of the multiple optical powers is calculated, and the optical power standard deviation is compared with a preset standard deviation threshold. If the optical power standard deviation is greater than the standard deviation threshold, it is determined that the light source module (2) is abnormal.

6. The transformer internal temperature detection system according to claim 3, characterized in that: Also includes a third self-diagnosis module (8-3); The third self-diagnosis module (8-3) is used to input the pre-stored reference optical signal into the demodulation module (3); The reference light signal is a grating reflected light signal corresponding to a calibrated temperature value; and obtaining a reference temperature value obtained by demodulating and processing the reference light signal from a signal processing module (4), and comparing the reference temperature value with the calibration temperature value, and if the difference between the reference temperature value and the calibration temperature value exceeds a preset temperature demodulation accuracy error, determining that the demodulation module (3) is abnormal; And the processing time from inputting the reference light signal into the demodulation module (3) to obtaining the reference temperature value is recorded, and if the processing time exceeds a preset time threshold, the demodulation module (3) is determined to be abnormal.

7. The transformer internal temperature detection system according to claim 3, characterized in that: Also includes a fourth self-diagnosis module (8-4); The fourth self-diagnosis module (8-4) is used to input standard temperature data into the signal processing module (4); And obtaining processed temperature data obtained by processing the standard temperature data from the signal processing module (4), and comparing the processed temperature data with the standard temperature data; if the difference between the processed temperature data and the standard temperature data exceeds a preset data processing error, the signal processing module (4) is determined to be abnormal.

8. The transformer internal temperature detection system according to claim 3, characterized in that: Also includes a fifth self-diagnosis module (8-5); The user of the fifth self-diagnosis module (8-5) inputs a first alarm test temperature value and a second alarm test temperature value to the monitoring alarm module (6), and respectively records the input time of the first alarm test temperature value and the second alarm test temperature value; The first alarm temperature test value is greater than the maximum threshold of the transformer internal temperature, and the second alarm temperature test value is less than the minimum threshold of the transformer internal temperature; and obtaining high temperature alarm information and the output time of the high temperature alarm information from the monitoring alarm module (6); if the high temperature alarm information cannot be obtained, or the low temperature alarm information is obtained, or the output time of the high temperature alarm information exceeds the preset time difference of the input time of the first alarm test temperature value, then the monitoring alarm module (6) is determined to be abnormal; and obtaining low temperature alarm information and the output time of the low temperature alarm information from the monitoring alarm module (6); If the low temperature alarm information cannot be obtained, or the high temperature alarm information is obtained, or the output time of the low temperature alarm information exceeds the preset time difference of the input time of the second alarm test temperature value, then the monitoring alarm module (6) is determined to be abnormal.

9. The transformer internal temperature detection system according to claim 4, 5, 6, 7 or 8, characterized in that: Also includes a data storage module (9); The data storage module (9) is used to store detection system information; The detection system information includes storing the transformer internal temperature measurement value, high temperature alarm information and low temperature alarm information.

10. The transformer internal temperature detection system according to claim 9, characterized in that: It also includes a wireless transmission module (10); The data storage module (9) is also used to transmit the detection system information to a host computer via the wireless transmission module (10).

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