A method for arranging leakage flux sensors inside a transformer

Abstract

The transformer internal leakage flux sensor arrangement method of the present invention has high monitoring sensitivity, enabling more timely detection of winding defects and greatly reducing manual labor intensity. While achieving excellent transformer winding defect monitoring, it reduces the use of a large number of sensors. By arranging leakage flux sensors at key locations, it effectively measures the internal leakage flux that reflects the state of the transformer windings. Furthermore, by observing changes in leakage flux at key locations, it can quickly detect whether winding defects have occurred in the transformer, realizing online monitoring of transformer winding defects based on leakage flux characteristic parameters, thereby ensuring the safe and stable continuous operation of the transformer. Moreover, it allows for flexible selection of whether to improve the monitoring effect of winding faults according to specific circumstances, making it more widely applicable.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, and in particular to a method for arranging leakage magnetic field sensors inside a transformer. Background Technology

[0002] With the continuous development of my country's economy and the continuous expansion of the power grid, users' requirements and reliance on power supply quality and reliability are becoming increasingly stronger. The distribution network is the most extensive and largest part of my country's power system and a key link in ensuring power supply. It directly faces end users, and its safe operation plays a decisive role in the normal operation of the entire power grid, directly affecting the reliability of power supply. As the core equipment in the distribution network, the distribution transformer bears the heavy responsibility of power distribution and voltage level transformation, and is an important guarantee for the safe, reliable and economical operation of the distribution network. If the distribution transformer fails, it will affect the power supply performance at best, and cause regional power outages at worst, and even further affect the stability of the power system, causing huge economic losses and even casualties.

[0003] According to the State Grid Corporation's summary report on transformer equipment, 70% to 80% of transformer faults are inter-turn faults in the windings. Transformer faults will seriously affect the reliability of power supply and the normal operation of the system. Timely detection of faults and taking corresponding measures to isolate the faults can avoid greater economic losses.

[0004] Currently, the main methods used to monitor winding deformation or inter-turn short circuits are vibration response method and dissolved gas analysis in oil. However, the above two monitoring methods have low monitoring sensitivity and cannot accurately identify winding defects. In addition, the dissolved gas analysis in oil requires manual oil sampling for observation, which can easily lead to a large waste of manpower, material resources and financial resources.

[0005] Previous studies have shown that transformer winding defects can cause changes in the distribution of leakage magnetic field. Therefore, monitoring the leakage magnetic field of transformers provides a new approach for online monitoring of two types of winding defects. Without considering the number of leakage magnetic field sensors installed, it is possible to effectively monitor transformer winding defects by arranging leakage magnetic field sensors evenly and densely in the winding area. However, this arrangement method is not only costly and difficult to install, but also too many intrusive sensors may threaten the safe and stable operation of the transformer, making it not feasible.

[0006] Therefore, those skilled in the art are dedicated to developing a method for arranging leakage magnetic field sensors inside a transformer, aiming to solve the defects existing in the prior art. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is that the traditional inter-turn fault monitoring method of the winding has low monitoring sensitivity and cannot accurately identify the specific defects of the winding; while the existing method of monitoring transformer winding defects by changing the leakage magnetic field distribution is costly, requires too many sensors, is difficult to install, and poses a threat to the stable operation of the transformer.

[0008] To achieve the above objectives, the first aspect of the present invention provides an arrangement of leakage flux sensors inside a transformer.

[0009] The leakage magnetic flux sensor inside the transformer is arranged as follows: a leakage magnetic flux sensor is arranged in the transformer winding end insulation and directly above the winding closest to the iron core; a leakage magnetic flux sensor is arranged in the transformer winding end insulation and directly above the winding furthest from the iron core.

[0010] The leakage magnetic flux sensor inside the transformer is arranged as follows: a leakage magnetic flux sensor is arranged in the insulation at the end of the transformer winding and directly below the winding closest to the iron core; a leakage magnetic flux sensor is arranged in the insulation at the end of the transformer winding and directly below the winding furthest from the iron core.

[0011] The leakage flux sensor inside the transformer is arranged in the oil at the height corresponding to the middle of the transformer winding, and on the outer side of the winding closest to the iron core.

[0012] Furthermore, the leakage magnetic field sensor located in the transformer winding end insulation can be installed in a pad of the transformer end insulation;

[0013] Furthermore, the leakage flux sensor located at the middle height of the transformer winding can be installed in the transformer oil next to the insulating pad at the end of the transformer.

[0014] Furthermore, the monitoring effect of the winding fault can be improved by increasing the number of leakage magnetic field sensors installed on the longitudinal section of each phase winding, thereby reducing the angle of the winding sector area monitored by the leakage magnetic field sensors on the longitudinal section.

[0015] A second aspect of the present invention provides a method for arranging leakage flux sensors inside a transformer, comprising the following steps:

[0016] Step 1: Place leakage flux sensors at corresponding positions on the two longitudinal sections A1 and A2 of the transformer phase A winding;

[0017] Step 2: Place leakage flux sensors at corresponding positions on the two longitudinal sections B1 and B2 of the transformer phase B winding;

[0018] Step 3: Place leakage flux sensors at corresponding positions on the two longitudinal sections C1 and C2 of the transformer's C-phase winding;

[0019] A1 and A2 are two longitudinal sections of the A-phase winding where the sensor is arranged; B1 and B2 are two longitudinal sections of the B-phase winding where the sensor is arranged; C1 and C2 are two longitudinal sections of the C-phase winding where the sensor is arranged.

[0020] The relative positions of phases A, B, and C of the transformer, as well as phases A1, A2, B1, B2, C1, and C2, are as follows: Figure 1 As shown;

[0021] Position 1 refers to the winding located in the end insulation of the transformer winding and directly above the winding closest to the iron core.

[0022] Position 2 is located in the transformer winding end insulation and directly above the winding furthest from the iron core;

[0023] The oil located at the middle height position of the transformer winding, and on the outer side of the winding closest to the iron core, is position 3;

[0024] The location located in the transformer winding end insulation, and directly below the winding closest to the iron core, is position 4;

[0025] Position 5 is located in the transformer winding end insulation and directly below the winding furthest from the iron core;

[0026] The relative positions of the internal leakage flux sensors of the transformer are shown in the diagram. Figure 2 As shown;

[0027] On section A1, the leakage magnetic field sensors are labeled A11, A12, A13, A14, and A15, respectively.

[0028] On section A2, the leakage magnetic field sensors are labeled A21, A22, A23, A24, and A25, respectively.

[0029] On section B1, the leakage magnetic field sensors are labeled B11, B12, B13, B14, and B15, respectively.

[0030] On section B2, the leakage magnetic field sensors are labeled B21, B22, B23, B24, and B25, respectively.

[0031] On section C1, the leakage magnetic field sensors are labeled C11, C12, C13, C14, and C15, respectively.

[0032] On section C2, the leakage magnetic field sensors are labeled C21, C22, C23, C24, and C25, respectively.

[0033] Furthermore, the arrangement of the leakage flux sensors inside the transformer, such as the leakage flux sensors at positions 1, 4, 2, and 5; if installed outside the transformer windings, when a winding deformation fault occurs, it is highly likely that the position of the sensor will change, and may even damage the sensor, affecting the effectiveness of the leakage flux sensors in monitoring winding faults.

[0034] Furthermore, the arrangement of the leakage flux sensors inside the transformer, such as the leakage flux sensors at positions 1, 4, 2, and 5, is installed in the insulation at the winding ends. When a winding fault occurs, the change in leakage flux at this location is relatively weaker than that on the outside of the winding. However, this location is more convenient to install and will not damage the sensor due to a winding fault, thus ensuring the effectiveness of winding fault monitoring.

[0035] Furthermore, the arrangement of the leakage flux sensor inside the transformer, such as the leakage flux sensor at position 3, is such that it is installed in the oil at the middle height position of the transformer winding and on the outside of the winding closest to the core; because when the winding fault occurs at the middle height position of the winding, the leakage flux change inside the winding end insulation is weak, that is, the leakage flux change at positions 1, 4, 2, and 5 is weak, therefore, the leakage flux sensor at position 3 can better monitor the fault at the middle height position of the winding;

[0036] By adopting the above scheme, the transformer internal leakage flux sensor arrangement method disclosed in this invention has the following advantages:

[0037] (1) The transformer internal leakage magnetic sensor arrangement method of the present invention uses leakage magnetic sensors to monitor transformer winding defects, so that manual oil sampling is not required, greatly reducing the labor intensity of manual labor. Compared with traditional monitoring methods, the monitoring sensitivity is high, and winding defects can be detected more promptly, thereby avoiding the expansion of losses.

[0038] (2) The transformer internal leakage flux sensor arrangement method of the present invention overcomes the mindset of realizing transformer winding defect monitoring by uniformly and densely arranging leakage flux sensors in the winding area. Through the innovative sensor arrangement method, the use of a large number of sensors is reduced while achieving excellent transformer winding defect monitoring. By arranging leakage flux sensors in key positions, the internal leakage flux that reflects the state of transformer winding can be effectively measured. Furthermore, by the change of leakage flux in key positions, the transformer can quickly react to whether winding defects have occurred, thereby realizing online monitoring of transformer winding defects based on leakage flux characteristic parameters, and thus ensuring the safe and stable continuous operation of the transformer.

[0039] (3) The transformer internal leakage magnetic sensor arrangement method of the present invention can be adjusted according to the specific transformer monitoring application by increasing the number of cross sections of leakage magnetic sensors installed in each phase winding, thereby reducing the angle of the winding sector area monitored by the leakage magnetic sensors on each cross section, so as to improve the monitoring effect of winding faults. It has a wide range of applications and can be applied in detail according to specific situations.

[0040] In summary, the transformer internal leakage flux sensor arrangement method disclosed in this invention has high monitoring sensitivity, enabling more timely detection of winding defects and significantly reducing manual labor intensity. While achieving excellent transformer winding defect monitoring, it reduces the use of numerous sensors. By arranging leakage flux sensors at key locations, it effectively measures the internal leakage flux reflecting the transformer winding status. Furthermore, changes in leakage flux at key locations can quickly indicate whether winding defects have occurred, achieving online monitoring of transformer winding defects based on leakage flux characteristic parameters. This ensures the safe and stable continuous operation of the transformer. Moreover, it allows for flexible selection of whether to enhance the monitoring effect of winding faults based on specific circumstances, making it more widely applicable.

[0041] The following will further explain the concept, specific technical solution and technical effects of the present invention in conjunction with specific embodiments, so as to fully understand the purpose, features and effects of the present invention. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the cross-sectional arrangement of the leakage flux sensor arrangement method inside the transformer according to the present invention;

[0043] Figure 2 This is a schematic diagram of the sensor arrangement position on the longitudinal section of the transformer internal leakage flux sensor arrangement method of the present invention;

[0044] In the diagram, A—phase A winding, A1 and A2—two longitudinal sections of the phase A winding where the sensor is arranged; B—phase B winding, B1 and B2—two longitudinal sections of the phase B winding where the sensor is arranged; C—phase C winding, C1 and C2—two longitudinal sections of the phase C winding where the sensor is arranged; 1, 2, 3, 4, 5—sensor placement positions; 6—transformer; 7—iron core. Detailed Implementation

[0045] The following describes several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, which are described exemplarily, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0046] Example 1: The method of the present invention is used to complete the arrangement of leakage magnetic field sensors for a three-phase three-limb box-type power transformer.

[0047] First, perform step 1: place leakage magnetic sensors at corresponding positions on the two longitudinal sections A1 and A2 of the transformer phase A winding;

[0048] Then proceed to step 2: Arrange leakage magnetic sensors at corresponding positions on the two longitudinal sections B1 and B2 of the transformer B-phase winding;

[0049] Finally, perform step 3: Arrange leakage magnetic sensors at corresponding positions on the two longitudinal sections C1 and C2 of the transformer's C-phase winding;

[0050] In the steps described above, A1 and A2 are two longitudinal sections of the A-phase winding where the sensor is arranged; B1 and B2 are two longitudinal sections of the B-phase winding where the sensor is arranged; and C1 and C2 are two longitudinal sections of the C-phase winding where the sensor is arranged.

[0051] In this specific embodiment, the position 1 is located in the transformer winding end insulation and directly above the winding closest to the iron core;

[0052] Position 2 is located in the transformer winding end insulation and directly above the winding furthest from the iron core;

[0053] The oil located at the middle height position of the transformer winding, and on the outer side of the winding closest to the iron core, is position 3;

[0054] The location located in the transformer winding end insulation, and directly below the winding closest to the iron core, is position 4;

[0055] Position 5 is located in the transformer winding end insulation and directly below the winding furthest from the iron core;

[0056] In this specific implementation, the leakage flux sensor in the transformer winding end insulation is installed in the pad of the transformer end insulation; the leakage flux sensor at the middle height of the transformer winding is installed in the transformer oil next to the pad of the transformer end insulation.

[0057] In this specific implementation, the leakage magnetic field sensor selected is an optical leakage magnetic field sensor, which has excellent anti-electromagnetic interference and can adapt to the complex environment inside the transformer.

[0058] After the arrangement method of this invention is completed, the three-phase three-column box-type power transformer can be put into practical application.

[0059] Under long-term operating conditions, transformer short circuits are inevitable. Short circuit impacts reduce the transformer winding's short circuit withstand capability and disrupt its stability. In this embodiment, under rated operating conditions, the average temperature of the copper coil in the winding is 105°C. When the transformer is subjected to a short circuit current impact, the current in the coil winding increases by tens of times instantaneously. This rapid change in current also causes a large amount of heat to accumulate in the winding that cannot be dissipated in time, resulting in an increase in winding temperature. The mechanical characteristics of the winding also change with the changes in electromagnetic and mechanical properties.

[0060] The optical leakage magnetic field sensors arranged on each longitudinal section of this invention can monitor the fault status of the winding in the corresponding 180° sector area; the optical leakage magnetic field sensors arranged on two transverse and longitudinal sections of each phase winding monitor the fault status of the entire phase winding; the specific installation and arrangement positions of the leakage magnetic field sensors in this embodiment 1 are as follows: Figures 1-2 As shown;

[0061] In this embodiment 1, after the sensor arrangement inside the transformer has been completed for a period of time, after the transformer is subjected to a short circuit, although the deformation is small, the small deformation has little impact on the stable operation of the transformer in the early stage. However, as the transformer is in operation for a long time, with the increase and accumulation of the number of short circuit impacts, this slight cumulative deformation will cause the winding structure to move considerably, causing a decrease in the radial and axial stability of the winding, or causing the winding to be twisted and deformed and damaged.

[0062] In this embodiment, the leakage magnetic field sensors on section A1 are labeled A11, A12, A13, A14, and A15, respectively.

[0063] On section A2, the leakage magnetic field sensors are labeled A21, A22, A23, A24, and A25, respectively.

[0064] On section B1, the leakage magnetic field sensors are labeled B11, B12, B13, B14, and B15, respectively.

[0065] On section B2, the leakage magnetic field sensors are labeled B21, B22, B23, B24, and B25, respectively.

[0066] On section C1, the leakage magnetic field sensors are labeled C11, C12, C13, C14, and C15, respectively.

[0067] On section C2, the leakage magnetic field sensors are labeled C21, C22, C23, C24, and C25, respectively.

[0068] In this embodiment 1, a total of 30 magnetic flux leakage sensors were installed;

[0069] The leakage flux sensor arranged in this embodiment 1 can promptly analyze the leakage magnetic field and electromagnetic force distribution based on the leakage flux changes monitored by the aforementioned leakage flux sensor after the transformer is subjected to a short circuit impact. Thus, based on the leakage flux points marked by the leakage flux sensor, the weak points of the winding that are easily damaged after being subjected to a short circuit impact can be found, helping maintenance personnel to assess the stability of the transformer and replace the winding in a timely manner. This prevents the impact from accumulating to a certain extent and affecting the stable and safe operation of the power system, thereby maintaining the stable operation of the power grid system.

[0070] Finally, after artificially creating a short circuit impact on the transformer until the transformer could no longer function properly, the 30 leakage magnetic sensors installed using the method in Example 1 were still in a working state after the transformer was scrapped.

[0071] Comparative Example 1: Arrangement of leakage flux sensors for a three-phase, three-limb box-type power transformer using existing common technical solutions.

[0072] In this comparative example 1, except for the arrangement and installation method of the magnetic flux leakage sensor, all other variables are completely consistent with those in example 1, using the same type of transformer and the same type of optical magnetic flux leakage sensor, etc.

[0073] The arrangement used in Comparative Example 1 involves uniformly and densely arranging leakage flux sensors in the winding areas of phases A, B, and C. Specifically, this uniformity and density means that 36 sampling points are evenly distributed across the winding area of ​​each phase, covering the axial and radial spaces of each winding. In total, 108 sampling points are required for this comparative example. Careful measurement is necessary during installation to ensure uniform spacing between the optical leakage flux sensor mounting points in both the axial and radial directions. Furthermore, all installation positions are located outside the transformer windings to ensure uniform spacing.

[0074] Subsequently, testers artificially created a short circuit in the transformer, subjecting the transformer of Comparative Example 1 to a short-circuit impact. After the first short-circuit impact, the electromagnetic and mechanical properties of the windings changed due to the short-circuit current. The uniform and densely arranged leakage flux sensors can accurately monitor the windings with more severe deformation, and can also effectively monitor the winding deformation occurring at the middle height of the transformer windings. After the first artificially created short circuit, the monitoring effect shown by Comparative Example 1 is in line with the technical requirements.

[0075] Subsequently, artificial short circuits were created on the transformer. As the number of artificial short circuits increased, the deformation of the winding gradually increased. The leakage magnetic field sensors, which uniformly covered each axial and radial space, were installed on the outside of the transformer winding. Due to the deformation of the winding, the installation position of the sensors changed slightly. Therefore, when the winding deformed again, the specific location of the winding deformation could not be accurately displayed based on the leakage magnetic field data. However, the general working condition of the winding could still be monitored.

[0076] To better simulate the actual working conditions of the transformer, short-circuit impacts were continuously applied to the transformer manually. As the transformer continued to be subjected to short-circuit impacts, the winding deformation continued to increase. Gradually, the installed optical leakage magnetic sensors were damaged due to the deformation of the windings. Furthermore, as the winding deformation increased in the later stages, the number of damaged optical leakage magnetic sensors increased. Ultimately, the transformer suffered too many short-circuit impacts and could not complete the voltage conversion work, resulting in transformer damage.

[0077] In the specific implementation of Comparative Example 1, after the transformer reached the end of its service life, only 49 of the initially installed leakage magnetic sensors were still able to receive leakage magnetic signals after Comparative Example 1 was completed.

[0078] Comparative Analysis: Through the analysis of Example 1 and Comparative Example 1, it can be seen that the innovative design of the present invention reduces the number of leakage magnetic field sensors used by 3.6 times compared with Comparative Example 1 while achieving the same effect. Furthermore, due to the innovative arrangement scheme, Example 1 ensures that the leakage magnetic field sensors are not affected by the deformation of the transformer windings during the monitoring process, and can always work normally to record the leakage magnetic field of the transformer windings. Moreover, the sensors will not affect the normal operation of the transformer due to their own damage.

[0079] In summary, the transformer internal leakage flux sensor arrangement method of the present invention has high monitoring sensitivity, enabling more timely detection of winding defects and significantly reducing manual labor intensity. While achieving excellent transformer winding defect monitoring, it reduces the use of a large number of sensors. By arranging leakage flux sensors at key locations, it effectively measures the internal leakage flux reflecting the transformer winding status. Furthermore, changes in leakage flux at key locations can quickly indicate whether winding defects have occurred in the transformer, achieving online monitoring of transformer winding defects based on leakage flux characteristic parameters, thereby ensuring the safe and stable continuous operation of the transformer. Moreover, it allows for flexible selection of whether to improve the monitoring effect of winding faults according to specific circumstances, making it more widely applicable.

[0080] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A transformer internal leakage magnetic sensor arrangement method, characterized in that, comprising the following steps: Step 1: arranging leakage magnetic sensors at the corresponding positions of two longitudinal sections A1 and A2 of the A-phase winding of the transformer; Step 2: arranging leakage magnetic sensors at the corresponding positions of two longitudinal sections B1 and B2 of the B-phase winding of the transformer; Step 3: arranging leakage magnetic sensors at the corresponding positions of two longitudinal sections C1 and C2 of the C-phase winding of the transformer; Wherein, A1 and A2 are two longitudinal sections of the A-phase winding where sensors are arranged; B1 and B2 are two longitudinal sections of the B-phase winding where sensors are arranged; C1 and C2 are two longitudinal sections of the C-phase winding where sensors are arranged, so that by increasing the number of leakage magnetic sensors in each winding longitudinal section, the angle of the winding sector monitored by the leakage magnetic sensors in the longitudinal section is reduced; The arrangement of the transformer internal leakage magnetic sensors is as follows: in the transformer winding end insulation, directly above the winding closest to the core is position 1, where a leakage magnetic sensor is arranged; in the transformer winding end insulation, directly above the winding farthest from the core is position 2, where a leakage magnetic sensor is arranged; in the transformer winding end insulation, directly below the winding closest to the core is position 4, where a leakage magnetic sensor is arranged; in the transformer winding end insulation, directly below the winding farthest from the core is position 5, where a leakage magnetic sensor is arranged; in the oil corresponding to the middle height position of the transformer winding, on the outside of the winding closest to the core is position 3, where a leakage magnetic sensor is arranged; The leakage magnetic sensors arranged on each longitudinal section monitor the fault condition of the corresponding 180° sector winding; the leakage magnetic sensors arranged on the two longitudinal sections of each phase winding monitor the fault condition of the entire phase winding; five leakage magnetic sensors are installed on the longitudinal sections A1, A2, B1, B2, C1, and C2, respectively; The leakage magnetic sensors in the transformer winding end insulation are installed in the gasket of the transformer end insulation; the leakage magnetic sensors at the middle height position of the transformer winding are installed in the transformer oil beside the gasket of the transformer end insulation.

2. The transformer internal leakage magnetic sensor arrangement method of claim 1, characterized in that, When the winding fault occurs at the middle height position of the winding, the leakage magnetic change inside the winding end insulation is weak, i.e., the leakage magnetic change at positions 1, 4, 2, and 5 is weak, and the leakage magnetic sensor at position 3 can better monitor the fault at the middle height position of the winding. ​

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