Transformer operation temperature measurement accuracy self-diagnosis device and method

Abstract

The invention relates to a transformer operation temperature measurement accuracy self-diagnosis device and method. The device comprises a pointer thermometer, a self-diagnosis module, a monitoring display module and a power supply for supplying power to the device. A thermometer seat is arranged at the measuring end of the pointer thermometer and installed on the transformer oil tank, and a composite sensor located in the transformer oil tank is arranged in the thermometer seat and used for measuring the temperature in the transformer oil tank. The composite sensor comprises a pointer sensor measurement channel, a remote sensor measurement channel and a third temperature measurement channel which are mutually independent; measurement data of three groups of measurement channels of the composite sensor are transmitted to the self-diagnosis module, the self-diagnosis module performs measurement accuracy evaluation according to the measurement data and transmits an evaluation result to the monitoring display module, and the monitoring display module displays the evaluation result and the measurement data. Compared with the prior art, the method has the advantages of high accuracy, good practicability, high efficiency, convenience in use and the like.

Description

Technical Field

[0001] The invention relates to the technical field of transformer temperature monitoring, and in particular to a transformer operating temperature measurement accuracy self-diagnosis device and method. Background Art

[0002] The reliability of transformer thermal protection is closely related to the accuracy of the temperature measuring device. How to scientifically define the actual accuracy level of the pointer thermometer in use and accurately obtain the operating temperature data of the power transformer is crucial to ensure the safe operation of the transformer. The transformer pointer thermometer verification procedure requires that the inspection cycle shall not exceed one year, but the uninterrupted and continuous operation conditions of the substation cannot support the annual power outage of the transformer to inspect the temperature measuring device. Therefore, affected by the transformer maintenance interval, the actual calibration cycle of the temperature measuring device is usually six years, and the accuracy level of the temperature measuring device will change to a certain extent during the calibration cycle. The actual accuracy level of the temperature measuring device during operation is defined as the operating accuracy.

[0003] At the same time, the long-term uninterrupted and continuous operation of the transformer also brings challenges to the operating accuracy of the temperature measuring device. When the pointer thermometer or (and) the remote signal device in the temperature measuring device indicates an out-of-tolerance value, the transformer protection system will be falsely (or leaked) alarmed due to the out-of-tolerance value of the pointer thermometer. When there is a large deviation between the indication of the on-site pointer thermometer and the indication of the background remote signal device, it will be impossible to determine whether it is the fault of the temperature measuring device itself or the fault inside the substation equipment, which greatly increases the workload of equipment operation and maintenance, and may cause more serious accidents due to missing the best time for maintenance. In addition, the indication fault of the temperature measuring device in operation is currently mainly identified by the deviation of the two meters. There is a situation where the temperature measuring device "works with a disease" with an indication error exceeding the tolerance but the deviation of the two meters not exceeding the tolerance. At the same time, since the pointer thermometer in the temperature measuring device is a pressure thermometer with a capillary, the disassembly and assembly process of periodic calibration is prone to damage. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] This solution provides a transformer operating temperature measurement accuracy self-diagnosis device, including a pointer thermometer, a self-diagnosis module, a monitoring display module, and a power supply for the device;

[0007] The measuring end of the pointer thermometer is provided with a thermometer seat, and the thermometer seat is installed on the transformer oil tank. The thermometer seat is provided with a composite sensor located inside the transformer oil tank for measuring the temperature inside the transformer oil tank. The composite sensor includes a pointer sensor measurement channel, a remote sensor measurement channel and a third temperature measurement channel which are independent of each other.

[0008] The measurement data of the three measurement channels of the composite sensor are transmitted to the self-diagnosis module, and the self-diagnosis module evaluates the measurement accuracy according to the measurement data and transmits the evaluation result to the monitoring and display module, and the monitoring and display module displays the evaluation result and the measurement data.

[0009] Furthermore, the pointer sensor measurement channel adopts a magnetoelectric angle sensor.

[0010] Furthermore, the remote sensor measurement channel and the third temperature measurement channel both use thermal resistor PT100.

[0011] Furthermore, the thermometer seat is also provided with an environment temperature monitoring channel, the environment temperature monitoring channel is independent of each measuring channel of the composite sensor, and the temperature measuring element of the environment temperature monitoring channel adopts a thermal resistor PT100.

[0012] Furthermore, the self-diagnosis module is connected to the monitoring and display module via Bluetooth communication.

[0013] This scheme also provides a transformer operating temperature measurement accuracy self-diagnosis method, including the following steps:

[0014] The preset maximum allowable indication error and factory preset data are stored in the self-diagnosis module;

[0015] Measuring the temperature in the transformer mailbox through three independent measurement channels in the composite sensor, and transmitting the three measurement results to the self-diagnosis module;

[0016] The self-diagnosis module uses the horizontal and vertical comparison method to evaluate the measurement accuracy of the transformer oil tank operating temperature on the measurement results of each measurement channel. The horizontal and vertical comparison method includes horizontally comparing the three groups of measurement results with the preset maximum allowable indication error, and vertically comparing them with the factory preset data;

[0017] The monitoring display module displays the measurement values ​​of the three groups of measurement channels and the measurement accuracy evaluation results of the transformer oil tank operating temperature by the self-diagnosis module.

[0018] Furthermore, the specific steps of horizontally comparing the three groups of measurement results with the preset maximum allowable indication error include:

[0019] If the maximum allowable indication error of the measurement results of the three groups of measurement channels is less than or equal to the preset maximum allowable indication error, and the absolute value of the difference between the measurement results of any two groups of measurement channels is less than or equal to twice the preset maximum allowable indication error, then the transformer operating temperature measurement accuracy meets the requirements.

[0020] Furthermore, the preset maximum allowable indication error is the product of the accuracy grade and the measuring range of the pointer thermometer.

[0021] Furthermore, in addition to the three groups of measurement channels of the composite sensor, an independent ambient temperature monitoring channel is also provided, which measures the ambient temperature of the transformer oil tank to eliminate the influence of the ambient temperature on the operation accuracy of each measurement channel of the composite sensor.

[0022] Furthermore, one group of measurement channels of the composite sensor is measured by a magnetoelectric angle sensor, and the other two groups of measurement channels and the ambient temperature monitoring channel are measured by a thermal resistor PT100.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) This scheme adopts a state evaluation method based on big data to perform online digital evaluation on the measurement accuracy of transformer operating temperature. The real-time temperature of the transformer operation is obtained through three sets of independent measurement channels, and the three sets of independent measurement results are compared horizontally. At the same time, the factory preset data is used for vertical comparison to judge the operating accuracy of the temperature measuring device. The vertical comparison ensures that the measurement errors of each measurement channel are accurate. It is highly efficient and suitable for handling situations where there are small indication errors in the measurement channels. This measurement method has high accuracy, good practicality, high efficiency and is easy to use.

[0025] (2) This scheme sets up an independent ambient temperature monitoring channel in addition to the three groups of independent measurement channels. The ambient temperature monitoring channel and the three groups of independent measurement channels are set in the same thermometer holder. By referring to the ambient temperature measured by the ambient temperature monitoring channel, the influence of the ambient temperature on the operation accuracy of each measurement channel can be eliminated, thereby further improving the accuracy and effectiveness of the evaluation.

[0026] (3) The transformer digital intelligent temperature sensing method based on digital evaluation technology in this scheme can improve the operating accuracy of the transformer temperature measuring device, provide reliable decision-making support and sufficient response time for user units, thereby ensuring the safety and reliability of transformer equipment operation, and reduce power outages caused by false alarms of abnormal transformer oil temperature, as well as reduce the workload of daily operation and maintenance and the number of fault repairs, and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A schematic diagram of the structure of the self-diagnosis device provided by the present invention;

[0028] Figure 2 The present invention is a flowchart of the self-diagnosis method. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0033] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0034] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0035] Example 1

[0036] like Figure 1 , This embodiment provides a transformer operating temperature measurement accuracy self-diagnosis device, including a pointer thermometer, a self-diagnosis module, a monitoring display module, and a power supply for powering the device;

[0037] A thermometer seat is provided at the measuring end of the pointer thermometer, and the thermometer seat is installed on the transformer oil tank. A composite sensor located inside the transformer oil tank is provided in the thermometer seat for measuring the temperature inside the transformer oil tank. The composite sensor includes a pointer sensor measurement channel, a remote sensor measurement channel and a third temperature measurement channel which are independent of each other.

[0038] The measurement data of the three measurement channels of the composite sensor are transmitted to the self-diagnosis module, which evaluates the measurement accuracy according to the measurement data and transmits the evaluation results to the monitoring and display module, which displays the evaluation results and the measurement data.

[0039] In a preferred embodiment, the pointer sensor measurement channel adopts a magnetoelectric angle sensor. Currently, the widely used pointer measuring sensors mainly include pressure-sensitive sensors, photoelectric angle sensors and magnetoelectric angle sensors. However, the structure of the pressure-sensitive sensor is relatively complex, and it is connected to the pointer temperature measurement system. Its anti-interference ability is general, and its accuracy is relatively low. The photoelectric angle sensor also has a relatively complex structure and belongs to contact measurement. It will affect the driving mechanism of the pointer indication and the accuracy of the pointer, and its use cost is relatively high. In contrast, the structure of the magnetoelectric angle sensor is relatively simple, and the magnetoelectric angle sensor belongs to the suspended non-contact measurement, which will not produce wear and tear, and at the same time avoids errors or faults caused by contact. Therefore, it has high measurement accuracy, can provide accurate angle information, and has relatively low cost, which is conducive to popularization and application.

[0040] However, the technical indicators of the existing magnetic angle sensor can basically meet the requirements of the present invention, but its structure is not suitable for installation inside the pointer thermometer, so it is necessary to carry out structural modification based on the existing magnetic angle sensor.

[0041] First, remove the housing of the magnetic angle sensor, then install the core measuring end into the custom housing, and fix it in the pointer thermometer. The detailed parameters of the structurally modified magnetic angle sensor are: working voltage 3.3-5V, working current ≤15mA, measuring range 360°, resolution ≤0.0014°, output type TTL serial port.

[0042] The angle signal output of the modified pointer thermometer was tested, and the test results are shown in Table 1. The standard deviation of the angle output repeatability is ≤0.2°, which is consistent with the repeatability of the pointer thermometer at 0.2°, and the angle output error has not increased, which confirms the practicality and reliability of the magnetic angle sensor after the structural modification.

[0043] Table 1 Test results of angle signal output of modified pointer thermometer

[0044]

[0045] Furthermore, both the remote sensor measurement channel and the third temperature measurement channel use thermal resistor PT100. Among them, the remote sensors commonly used are thermal resistor PT100 and thermocouple, but the thermocouple sensor is relatively large in size and has good stability, but its accuracy is low and is greatly affected by the temperature of the measuring end. In contrast, the advantages of thermal resistor PT100 are more significant, including small size, good stability, high accuracy, and the measuring end is less affected by temperature. Therefore, the use of thermal resistor PT100 to measure the transformer tank temperature is less affected by temperature and the measurement results are more accurate.

[0046] In a preferred embodiment, the thermometer seat is further provided with an environment temperature monitoring channel, the environment temperature monitoring channel is independent of each measuring channel of the composite sensor, and the temperature measuring element of the environment temperature monitoring channel adopts a thermal resistor PT100.

[0047] An independent ambient temperature monitoring channel is set up outside the three independent measurement channels. The ambient temperature monitoring channel and the three independent measurement channels are set in the same thermometer holder. By referring to the ambient temperature measured by the ambient temperature monitoring channel, the influence of the operating accuracy of each measurement channel caused by the ambient temperature can be eliminated, thereby further improving the accuracy and effectiveness of the evaluation.

[0048] Specifically, the self-diagnosis module is connected to the monitoring display module via Bluetooth communication. Bluetooth communication can operate normally in low-power mode, so it performs well in applications that need to balance speed and energy consumption. At the same time, it can also support a variety of complex network situations, and the product size is relatively small, which is easy to integrate and apply, and the security performance of Bluetooth data transmission is high.

[0049] In order to further confirm the feasibility of Bluetooth communication for the application of temperature measurement data transmission in this transformer, the anti-electromagnetic interference performance when using Bluetooth was tested, and the results are shown in Table 2. The test results show that the network delay when using the Bluetooth method for temperature measurement data transmission is less than 200ms, which is in line with the expected effect.

[0050] Table 5 Bluetooth data transmission network delay test results

[0051]

[0052] like Figure 2 As shown, this embodiment also provides a transformer operating temperature measurement accuracy self-diagnosis method, comprising the following steps:

[0053] S1: Store the preset maximum allowable indication error and factory preset data in the self-diagnosis module;

[0054] S2: Measure the temperature in the transformer mailbox through three independent measurement channels in the composite sensor, and transmit the three measurement results to the self-diagnosis module;

[0055] S3: The self-diagnosis module uses the horizontal and vertical comparison method to evaluate the measurement accuracy of the transformer oil tank operating temperature on the measurement results of each measurement channel. The horizontal and vertical comparison method includes horizontally comparing the three groups of measurement results with the preset maximum allowable indication error, and vertically comparing them with the factory preset data;

[0056] If the maximum allowable indication error of the measurement results of the three groups of measurement channels is less than or equal to the preset maximum allowable indication error, and the absolute value of the difference between the measurement results of any two groups of measurement channels is less than or equal to twice the preset maximum allowable indication error, then the transformer operating temperature measurement accuracy meets the requirements;

[0057] S4: The monitoring display module displays the measurement values ​​of the three groups of measurement channels and the measurement accuracy evaluation results of the self-diagnosis module on the operating temperature of the transformer oil tank.

[0058] A status evaluation method based on big data is used to conduct online digital evaluation of the transformer operating temperature measurement accuracy. The real-time temperature of the transformer operation is obtained through three independent measurement channels, and the three independent measurement results are compared horizontally. At the same time, a vertical comparison is performed in combination with the factory preset data to judge the operating accuracy of the temperature measuring device. The vertical comparison ensures that the measurement errors of each measurement channel are accurate, and the efficiency is high. It is suitable for processing situations where there are small indication errors in the measurement channels. This measurement method has high accuracy, good practicability, high efficiency and is easy to use.

[0059] Among them, the preset maximum allowable indication error is the product of the accuracy grade and the measuring range of the pointer thermometer.

[0060] Preferably, an independent ambient temperature monitoring channel is provided in addition to the three groups of measurement channels of the composite sensor, so as to eliminate the influence of the ambient temperature on the operation accuracy of each measurement channel of the composite sensor by measuring the ambient temperature of the transformer oil tank.

[0061] Specifically, one group of measurement channels of the composite sensor is measured by a magnetoelectric angle sensor, and the other two groups of measurement channels and the ambient temperature monitoring channel are measured by a thermal resistor PT100.

[0062] Among them, the self-diagnosis module is controlled by a single-chip microcomputer, which integrates multiple functional modules such as CPU, memory, input / output ports, timers and communication interfaces into one chip, which simplifies the design of the entire system and reduces the use of external devices. In addition, the single-chip microcomputer is small in size and occupies little space. It is suitable for application scenarios with size restrictions or miniaturization requirements, and the system design is flexible.

[0063] Specifically, this embodiment forms three channels, namely, an angle sensor measurement channel corresponding to the indication of the pointer thermometer with a temperature package as a sensor, a measurement channel with Pt100-A as a sensor, and a measurement channel with Pt100-B as a sensor. The sensors of the three groups of measurement channels are called composite sensors, which are installed in the same thermometer seat on the top of the transformer tank for temperature measurement. At the same time, in order to eliminate the influence of the operating accuracy of each measurement channel due to the ambient temperature, a group of ambient temperature monitoring channels with Pt100-H as the temperature measuring element are added.

[0064] The analog or digital signals output by the temperature measuring elements of the three measurement channels and the ambient temperature monitoring channel will be sent to the self-diagnosis module at the same time, and the self-diagnosis module will complete the online real-time digital evaluation of the operating accuracy of the temperature measuring device and the remote signal output. The self-diagnosis module uses a state evaluation method based on big data for online digital evaluation: read the real-time temperature values ​​of the three measurement channels for horizontal comparison, and the maximum allowable indication error δ1 of the temperature measurement channel is the product of its accuracy level and range. The three measurement channels should meet this requirement. The absolute value of the difference between the real-time temperature values ​​of any two measurement channels of the temperature measuring device that meets the requirements for operating accuracy should not be greater than 2 times δ1. And make a vertical comparison with the factory preset data to determine the operating accuracy status of the temperature measuring device, which is suitable for processing small indication errors.

[0065] Among them, the indication failure of the pointer thermometer is mainly caused by the negative deviation due to chronic leakage of the closed system. Therefore, the actual measurement verification process for the effectiveness of digital evaluation is to verify the typical fault conditions that produce different negative deviations of the pointer thermometer. The real-time fault omission judgment in the theoretical verification can be verified by changing the fault quantity of the other two groups of measurement channels.

[0066] The verification results show that when the digital evaluation method of the temperature measuring device provides an annual digital evaluation report in units of years, the evaluation efficiency is as high as 97.82%. In order to ensure the reliability of the digital intelligent temperature sensing device for transformers, the product was sent to a third-party testing agency for type testing.

[0067] The verification results confirm that the transformer digital intelligent temperature sensing method based on digital evaluation technology in the present invention can improve the operating accuracy of the transformer temperature measuring device, provide reliable decision-making support and sufficient response time for user units, thereby ensuring the safety and reliability of transformer equipment operation, and can reduce power outages caused by false alarms of abnormal transformer oil temperature, as well as reduce the workload of daily operation and maintenance and the number of fault repairs, and has good application value and prospects.

[0068] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A transformer operating temperature measurement accuracy self-diagnosis device, characterized in that: It includes a pointer thermometer, a self-diagnosis module, a monitoring and display module, and a power supply for powering the device; The measuring end of the pointer thermometer is provided with a thermometer seat, and the thermometer seat is installed on the transformer oil tank. The thermometer seat is provided with a composite sensor located inside the transformer oil tank for measuring the temperature inside the transformer oil tank. The composite sensor includes a pointer sensor measurement channel, a remote sensor measurement channel and a third temperature measurement channel which are independent of each other. The measurement data of the three measurement channels of the composite sensor are transmitted to the self-diagnosis module, and the self-diagnosis module evaluates the measurement accuracy according to the measurement data and transmits the evaluation result to the monitoring and display module, and the monitoring and display module displays the evaluation result and the measurement data.

2. A transformer operating temperature measurement accuracy self-diagnosis device according to claim 1, characterized in that: The pointer sensor measurement channel adopts a magnetoelectric angle sensor.

3. A transformer operating temperature measurement accuracy self-diagnosis device according to claim 1, characterized in that: The remote sensor measurement channel and the third temperature measurement channel both use thermal resistor PT100.

4. A transformer operating temperature measurement accuracy self-diagnosis device according to claim 1, characterized in that: The thermometer seat is also provided with an environment temperature monitoring channel, which is independent of each measuring channel of the composite sensor, and the temperature measuring element of the environment temperature monitoring channel adopts a thermal resistor PT100.

5. A transformer operating temperature measurement accuracy self-diagnosis device according to claim 1, characterized in that: The self-diagnosis module is connected to the monitoring and display module via Bluetooth communication.

6. A transformer operating temperature measurement accuracy self-diagnosis method, characterized in that: The following steps are involved: The preset maximum allowable indication error and factory preset data are stored in the self-diagnosis module; Measuring the temperature in the transformer mailbox through three independent measurement channels in the composite sensor, and transmitting the three measurement results to the self-diagnosis module; The self-diagnosis module uses the horizontal and vertical comparison method to evaluate the measurement accuracy of the transformer oil tank operating temperature on the measurement results of each measurement channel. The horizontal and vertical comparison method includes horizontally comparing the three groups of measurement results with the preset maximum allowable indication error, and vertically comparing them with the factory preset data; The monitoring display module displays the measurement values ​​of the three groups of measurement channels and the measurement accuracy evaluation results of the transformer oil tank operating temperature by the self-diagnosis module.

7. A transformer operating temperature measurement accuracy self-diagnosis method according to claim 6, characterized in that: The specific steps of horizontally comparing the three groups of measurement results with the preset maximum allowable indication error include: If the maximum allowable indication error of the measurement results of the three groups of measurement channels is less than or equal to the preset maximum allowable indication error, and the absolute value of the difference between the measurement results of any two groups of measurement channels is less than or equal to twice the preset maximum allowable indication error, then the transformer operating temperature measurement accuracy meets the requirements.

8. A transformer operating temperature measurement accuracy self-diagnosis method according to claim 6, characterized in that: The preset maximum allowable indication error is the product of the accuracy grade and the measuring range of the pointer thermometer.

9. A transformer operating temperature measurement accuracy self-diagnosis method according to claim 6, characterized in that: In addition to the three groups of measurement channels of the composite sensor, an independent ambient temperature monitoring channel is also provided. By measuring the ambient temperature of the transformer oil tank, the influence of the ambient temperature on the operation accuracy of each measurement channel of the composite sensor is eliminated.

10. A transformer operating temperature measurement accuracy self-diagnosis method according to claim 9, characterized in that: One group of measurement channels of the composite sensor is measured by a magnetoelectric angle sensor, and the other two groups of measurement channels and the ambient temperature monitoring channel are measured by a thermal resistor PT100.

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