Method and system for detecting temperature field distribution in oil tank of oil-immersed transformer

Abstract

The invention discloses an oil-immersed transformer oil tank internal temperature field distribution detection method and system, and the method comprises the following steps: 1) manufacturing a distributed temperature measurement device, and placing the distributed temperature measurement device in an oil tank, so as to detect the temperature data of the front and side surfaces in the transformer oil tank; 2) connecting the distributed temperature measuring device with an external demodulation unit to obtain temperature data, performing data cleaning on the obtained temperature data, and removing abnormal temperature data; and 3) performing grid division on the front surface and the side surface in the oil tank, calculating grid type temperature data of each grid point based on the cleaned temperature data, and drawing a temperature field distribution cloud picture in the transformer oil tank based on the grid type temperature data. Partial discharge caused by insulation damage due to the fact that the optical fiber is directly installed on the winding and the iron core can be effectively avoided, insulation of the winding and the iron core is not affected once the optical fiber is damaged, temperature field distribution in the oil tank can be accurately obtained, and the device has the advantages of being safe, efficient, easy to replace, high in measurement precision and the like.

Description

Technical Field

[0001] The invention relates to the technical field of transformers, and in particular to a method and system for detecting the internal temperature field distribution of an oil tank of an oil-immersed transformer. Background Art

[0002] Power transformers are the most important substation equipment in the power system and are widely used in various power transmission and distribution networks. The reliability of power transformers directly affects the stable operation of the power grid. With the continuous improvement of the voltage level and capacity of my country's power grid, the failure problems caused by local overheating inside the transformer are becoming more and more serious, and the losses caused by overheating failures are also increasing. When a transformer overheats, if it is not handled in time, it may accelerate the aging of the transformer, shorten the life of the transformer, and may also cause a short circuit between the winding turns. In severe cases, it may directly damage the transformer.

[0003] At present, there are two methods for obtaining the hot spot temperature of transformer windings: measurement method and top oil temperature model inversion calculation method. The measurement method requires placing the temperature probe in the transformer winding coil to obtain real-time temperature data. The real-time temperature data obtained by this method has high accuracy, but the disadvantage is that the transformer needs to be shut down for modification, which increases the cost of transformer production, affects the normal operation of the power grid, and does not meet the requirements of economic operation of the power grid. The top oil temperature model inversion method measures the top oil temperature of the oil tank and further uses mathematical and physical principles such as thermal simulation method, numerical calculation method, and thermal circuit model method to estimate the hot spot temperature. However, since the actual transformer operation is often quite different from the ideal situation, coupled with calculation errors and nonlinear errors, the calculated hot spot temperature value is quite different from the actual one, and the distribution of the temperature field inside the oil tank cannot be accurately obtained.

[0004] Patent document with publication number CN117235909A proposes to measure the temperature field distribution inside the oil tank by using an ultrasonic transducer outside the oil tank, and actively transmit ultrasonic signals to the inside of the oil tank. Since the structure and material of the transformer are known, only the temperature factor will affect the ultrasonic return signal. By analyzing the returned ultrasonic signal, the internal temperature information can be obtained. The disadvantage of this method is that the internal structure and material of the oil-immersed transformer to be tested must be clearly known, and the calculation model must be built in advance. Once the transformer model changes, the model must be re-modeled, which is cumbersome. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art, thereby providing a method and system for detecting the internal temperature field distribution of the oil tank of an oil-immersed transformer. The method adopts a distributed temperature measuring optical fiber fixed on an insulating rod to measure the internal temperature field distribution of the oil tank of the oil-immersed transformer, which can accurately obtain the distribution of a certain plane of the temperature field inside the oil tank, and can effectively avoid the situation where the optical fiber is directly installed on the winding and the core, resulting in insulation damage and local discharge. When the optical fiber is damaged, it is easy to replace it without affecting the safe operation of the equipment. At the same time, the internal temperature field distribution of the oil tank can also be accurately obtained, which has the advantages of safety, high efficiency, high measurement accuracy, etc.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for detecting the temperature field distribution inside an oil tank of an oil-immersed transformer comprises the following steps: 1) Make a distributed temperature measuring device and place it inside the oil tank to detect the temperature data on the front and side of the transformer oil tank; 2) Connect the distributed temperature measurement device to the external demodulation unit to obtain temperature data, clean the obtained temperature data, and remove abnormal temperature data; 3) Divide the front and side of the oil tank into grids, calculate the grid temperature data of each grid point based on the temperature data after cleaning, and draw a cloud map of the temperature field distribution inside the transformer oil tank based on the grid temperature data.

[0007] The distributed temperature measuring device in step 1) is composed of an insulating bracket and temperature measuring optical fibers distributed on the insulating bracket.

[0008] The insulating support is composed of insulating rods with a common origin, and each insulating rod has more than five temperature measuring optical fibers distributed at equal intervals; The two horizontal insulating rods are the same length as the length and width of the bottom of the transformer oil tank, and are connected to each other at an angle of 90°. One vertical insulating rod is the same length as the height of the transformer oil tank and is connected to the connection points of the two horizontal insulating rods. The other two insulating rods with an angle of 45° are located on the front and side of the oil tank, and one end of each end is connected to the connection points of the two horizontal insulating rods.

[0009] The density of the material used to make the insulating rod is greater than twice the density of transformer oil, and the insulating rod bracket is located inside the oil tank by its own weight.

[0010] Each temperature measuring optical fiber on the distributed temperature measuring device is connected to an external demodulation unit via an optical fiber through-hole.

[0011] The acquired temperature data is cleaned to remove abnormal temperature data, specifically: The average temperature value of the measured temperature data is calculated, and then the abnormal temperature data whose temperature value exceeds 50% of the average temperature value are eliminated.

[0012] The front and side surfaces of the oil tank are meshed, and the grid temperature data of each grid point is calculated based on the temperature data after cleaning. The temperature field distribution cloud map of the transformer oil tank is drawn based on the grid temperature data. Specifically: According to the internal dimensions of the transformer oil tank, a rectangular coordinate system is established with one end point at the bottom of the transformer oil tank. The coordinates of each temperature measuring optical fiber on the distributed temperature measuring device are calculated, and the measured plane is evenly gridded. The grid point spacing is not less than 0.5 times the temperature measurement point spacing. Based on the cleaned temperature data, the temperature data of the grid points is calculated by the interpolation smoothing method, and the temperature field distribution cloud map inside the tank is drawn based on the grid temperature data.

[0013] A temperature field distribution detection system for an oil-immersed transformer tank, comprising: A temperature measuring device for distributed detection of temperature signals inside the oil tank, the temperature measuring device comprising an insulating bracket and temperature measuring optical fibers distributed on the insulating bracket; An optical fiber demodulation unit for converting demodulated optical signals into temperature values, the optical fiber demodulation unit being connected to the temperature measuring optical fiber via an optical fiber through-hole; A data processing unit, the data processing unit is used to clean the temperature data acquired by the optical fiber demodulation unit and remove abnormal temperature data; and a temperature distribution cloud map drawing unit, wherein the front and side surfaces of the oil tank are gridded, the grid temperature data of each grid point is calculated based on the temperature data after cleaning, and a temperature field distribution cloud map of the transformer oil tank is drawn based on the grid temperature data.

[0014] The insulating support is composed of insulating rods with a common origin, and each insulating rod has more than five temperature measuring optical fibers distributed at equal intervals; The two horizontal insulating rods are the same length as the length and width of the bottom of the transformer oil tank, and are connected to each other at an angle of 90°. One vertical insulating rod is the same length as the height of the transformer oil tank and is connected to the connection points of the two horizontal insulating rods. The other two insulating rods with an angle of 45° are located on the front and side of the oil tank, and one end of each end is connected to the connection points of the two horizontal insulating rods.

[0015] Compared with the prior art, the present invention mainly has the following advantages: The present invention adopts a method of fixing the distributed temperature measurement optical fiber on the insulating rod. Compared with the method of directly pre-burying the optical fiber on the winding core, the operation is simple and it is convenient to replace the optical fiber when it is damaged. It does not affect the use of the temperature measurement function and avoids the insulation damage caused by directly installing the optical fiber on the winding and the core, thereby reducing the risk of partial discharge.

[0016] Compared with the indirect measurement method, the present invention can directly and accurately obtain the planar distribution of the internal temperature field of the oil-immersed transformer, avoid the measurement errors caused by calculation and model, monitor the temperature field inside the transformer in real time, effectively prevent the transformer from overheating and damage, and improve the equipment operation efficiency.

[0017] The present invention is safe and efficient; the insulating rod bracket can be fixed inside the oil tank by its own weight, no separate fixing structure is required, and the safe operation of the equipment is not affected; meanwhile, the efficiency of temperature measurement and the accuracy and practicability of detection are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the basic flow chart of the method provided by the present invention; Figure 2 A schematic diagram of the system structure provided by the present invention; Figure 3 It is a right side view of the transformer oil tank of the present invention. DETAILED DESCRIPTION

[0019] like Figure 1 , Figure 2 As shown, this embodiment provides a method for detecting the temperature field distribution inside an oil tank of an oil-immersed transformer, comprising: 1) Make a distributed temperature measuring device and place it inside the oil tank to detect the temperature data on the front and sides of the transformer oil tank; the distributed temperature measuring device consists of an insulating bracket and temperature measuring optical fibers distributed on the insulating bracket. The insulating bracket consists of 5 insulating rods with a common origin, and each insulating rod has more than five temperature measuring optical fibers distributed at equal intervals; Two horizontal insulating rods are the same length as the bottom of the transformer oil tank, and are connected at an angle of 90°. One vertical insulating rod is the same length as the height of the transformer oil tank, and is connected to the connection point of the two horizontal insulating rods. The other two insulating rods with an angle of 45° are located on the front and side of the oil tank, and one end of each is connected to the connection point of the two horizontal insulating rods. The density of the material used to make the insulating rods is greater than twice the density of the transformer oil, and the insulating rod bracket is located inside the oil tank by its own weight.

[0020] 2) Connect each temperature measuring optical fiber on the distributed temperature measuring device to an external demodulation unit 5 through an optical fiber through-hole 4 to obtain temperature data, calculate the average temperature value of the measured temperature data, and then remove abnormal temperature data whose temperature value exceeds 50% of the average temperature value; 3) According to the internal dimensions of the transformer oil tank, a rectangular coordinate system is established with one end point at the bottom of the transformer oil tank, the coordinates of each temperature measuring optical fiber on the distributed temperature measuring device are calculated, and the measured plane is evenly gridded. The grid point spacing is not less than 0.5 times the temperature measurement point spacing. Based on the cleaned temperature data, the temperature data of the grid points is calculated by the interpolation smoothing method, and the temperature field distribution cloud map inside the tank is drawn based on the grid temperature data.

[0021] In this embodiment, a 10kV oil-immersed distribution transformer prototype is used as the test object. The internal dimensions of the oil tank are 1.6m long*1.4m wide*1.5m high, and the internal temperature field distribution detection is carried out. Example

[0022] like Figure 2 , Figure 3 As shown in the figure, the insulating bracket is composed of 5 insulating rods with a common origin, including 2 horizontal insulating rods, 1 vertical insulating rod and 2 45° inclined insulating rods, of which the 2 45° inclined insulating rods are located on the front and side of the oil tank respectively. The length of the insulating rod is customized according to the internal size of the oil tank, and the size is reduced by 15cm in each direction compared with the internal size of the oil tank to ensure that the temperature measurement area can cover the entire winding area.

[0023] In this embodiment, the temperature measuring optical fiber is fixed to the surface of the insulating rod by bonding, and 6 evenly distributed optical fiber temperature measuring points are set on each insulating rod. A distributed temperature measuring optical fiber is fixed on each insulating rod, a total of 5, which are connected to the external optical fiber demodulation equipment through 5 optical fiber through-holes.

[0024] In this embodiment, the temperature measuring optical fiber sensor adopts a fiber Bragg grating (FBG) sensor, whose measurement range is -50°C to 500°C and temperature resolution is 0.1°C, meeting the basic requirements for temperature measurement inside the transformer.

[0025] In this embodiment, the intersection of the insulating rods is selected as the origin of the coordinate system, and a rectangular coordinate system is established. Taking the right side of the oil tank as an example, the corresponding temperature measurement plane is the XZ plane, and the coordinates of the distributed optical fiber temperature measurement points are calculated. The coordinates of the temperature measurement points at the horizontal position are: (20, 0, 0), (40, 0, 0), (60, 0, 0), (80, 0, 0), (100, 0, 0), (120, 0, 0), the coordinates of the temperature measurement points at the vertical position are: (0, 0, 20), (0, 0, 40), (0, 0, 60), (0, 0, 80), (0, 0, 100), (0, 0, 120), and the coordinates of the temperature measurement points at the oblique 45° angle are: (20, 0, 20), (40, 0, 40), (60, 0, 60), (80, 0, 80), (100, 0, 100), (120, 0, 120). The measured plane is further divided into uniform grids with a grid point spacing of 15 cm. The temperature data of the grid points are calculated by the interpolation smoothing method, and the results of the temperature measurement points are retained. Finally, a cloud map of the temperature field distribution inside the fuel tank is drawn.

[0026] The present invention provides a temperature field distribution detection system inside an oil tank of an oil-immersed transformer, comprising: a temperature measuring device for distributed detection of temperature signals inside the oil tank, the temperature measuring device consisting of an insulating bracket 2 and a temperature measuring optical fiber 3 distributed on the insulating bracket; an optical fiber demodulation unit 5 for demodulating an optical signal and converting it into a temperature value, the optical fiber demodulation unit being connected to the temperature measuring optical fiber via an optical fiber through-hole; a data processing unit, the data processing unit being used to clean the temperature data acquired by the optical fiber demodulation unit and eliminate abnormal temperature data; and a temperature distribution cloud map drawing unit 6, the front and side surfaces of the oil tank are gridded, the grid temperature data of each grid point is calculated based on the cleaned temperature data, and the temperature field distribution cloud map inside the transformer oil tank is drawn based on the grid temperature data.

[0027] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting the temperature field distribution inside an oil tank of an oil-immersed transformer, characterized in that: The following steps are involved: 1) Make a distributed temperature measuring device and place it inside the oil tank to detect the temperature data on the front and side of the transformer oil tank; 2) Connect the distributed temperature measurement device to the external demodulation unit to obtain temperature data, clean the obtained temperature data, and remove abnormal temperature data; 3) Divide the front and side of the oil tank into grids, calculate the grid temperature data of each grid point based on the temperature data after cleaning, and draw a cloud map of the temperature field distribution inside the transformer oil tank based on the grid temperature data.

2. The method for detecting the temperature field distribution inside the oil tank of an oil-immersed transformer according to claim 1, characterized in that: The distributed temperature measuring device in step 1) is composed of an insulating bracket and temperature measuring optical fibers distributed on the insulating bracket.

3. The method for detecting the internal temperature field distribution of an oil tank of an oil-immersed transformer according to claim 2, characterized in that: The insulating support is composed of (5) insulating rods with a common origin, and each insulating rod has more than five temperature measuring optical fibers distributed at equal intervals; The two horizontal insulating rods are the same length as the length and width of the bottom of the transformer oil tank, and are connected to each other at an angle of 90°. One vertical insulating rod is the same length as the height of the transformer oil tank and is connected to the connection points of the two horizontal insulating rods. The other two insulating rods with an angle of 45° are located on the front and side of the oil tank, and one end of each end is connected to the connection points of the two horizontal insulating rods.

4. The method for detecting the temperature field distribution inside the oil tank of an oil-immersed transformer according to claim 1, characterized in that: The density of the material used to make the insulating rod is greater than twice the density of transformer oil, and the insulating rod bracket is located inside the oil tank by its own weight.

5. A method for detecting the internal temperature field distribution of an oil tank of an oil-immersed transformer according to claim 1 or 2, characterized in that: Each temperature measuring optical fiber on the distributed temperature measuring device is connected to an external demodulation unit via an optical fiber through-hole (4).

6. The method for detecting the temperature field distribution inside the oil tank of an oil-immersed transformer according to claim 1, characterized in that: The acquired temperature data is cleaned to remove abnormal temperature data, specifically: The average temperature value of the measured temperature data is calculated, and then the abnormal temperature data whose temperature value exceeds 50% of the average temperature value are eliminated.

7. The method for detecting the temperature field distribution inside the oil tank of an oil-immersed transformer according to claim 1, characterized in that: The front and side surfaces of the oil tank are meshed, and the grid temperature data of each grid point is calculated based on the temperature data after cleaning. The temperature field distribution cloud map of the transformer oil tank is drawn based on the grid temperature data. Specifically: According to the internal dimensions of the transformer oil tank, a rectangular coordinate system is established with one end point at the bottom of the transformer oil tank. The coordinates of each temperature measuring optical fiber on the distributed temperature measuring device are calculated, and the measured plane is evenly gridded. The grid point spacing is not less than 0.5 times the temperature measurement point spacing. Based on the cleaned temperature data, the temperature data of the grid points is calculated by the interpolation smoothing method, and the temperature field distribution cloud map inside the tank is drawn based on the grid temperature data.

8. A temperature field distribution detection system for an oil-immersed transformer tank, characterized in that: include: A temperature measuring device for distributed detection of temperature signals inside an oil tank, the temperature measuring device comprising an insulating bracket (2) and temperature measuring optical fibers (3) distributed on the insulating bracket; An optical fiber demodulation unit (5) for converting demodulated optical signals into temperature values, the optical fiber demodulation unit being connected to the temperature measuring optical fiber via an optical fiber through-hole; A data processing unit, the data processing unit is used to clean the temperature data acquired by the optical fiber demodulation unit and remove abnormal temperature data; and a temperature distribution cloud map drawing unit (6), wherein the front and side surfaces of the oil tank are gridded, grid temperature data of each grid point is calculated based on the temperature data after cleaning, and a temperature field distribution cloud map of the transformer oil tank is drawn based on the grid temperature data.

9. The system for detecting the internal temperature field distribution of an oil tank of an oil-immersed transformer according to claim 8, characterized in that: The insulating support is composed of (5) insulating rods with a common origin, and each insulating rod has more than five temperature measuring optical fibers (3) distributed at equal intervals; The two horizontal insulating rods are the same length as the length and width of the bottom of the transformer oil tank, and are connected to each other at an angle of 90°. One vertical insulating rod is the same length as the height of the transformer oil tank and is connected to the connection points of the two horizontal insulating rods. The other two insulating rods with an angle of 45° are located on the front and side of the oil tank, and one end of each end is connected to the connection points of the two horizontal insulating rods.

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