Power transformer winding fault complex frequency domain online diagnosis method and equipment

Abstract

The embodiment of the invention discloses a power transformer winding fault complex frequency domain online diagnosis method and device, and the method comprises the steps: obtaining the midpoint voltage of different windings of a power transformer under reference complex impedance, and obtaining the midpoint voltage distance vector between the different windings according to the midpoint voltage; and obtaining a winding fault diagnosis result of the power transformer according to the midpoint voltage distance vector and a preset midpoint voltage distance vector threshold. According to the embodiment, the neutral-point voltage vector can reflect the electrical state in the winding, compared with an existing detection method, the neutral-point voltage vector is more sensitive to winding faults, the influence of load fluctuation is relatively small, meanwhile, the neutral-point voltage vector is not prone to being influenced by electromagnetic interference and a wiring mode, and the detection accuracy is improved. Therefore, the mode of carrying out winding fault diagnosis according to the midpoint voltage distance obtained according to the midpoint voltage is not easy to cause misjudgment, and the accuracy of an on-line diagnosis result of the winding faults of the alternating-current transformer and the converter transformer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer winding fault judgment, and particularly to a complex frequency domain on-line diagnosis method and device for winding faults of an AC power transformer and a converter transformer. Background Art

[0002] In the power system, power transformers are widely used in substations and industrial sites because they can provide more voltage level options. Power transformers are usually configured with three independent windings, and each winding is connected to a different voltage level to meet different power demands. The correctness of the transformer winding is crucial for the stable operation of the system, and incorrect connection of the winding may lead to serious power accidents and equipment damage. Therefore, judging and ensuring the correctness of the power transformer winding has become an important issue.

[0003] As the core equipment of a new power system, the on-line diagnosis of the winding state of AC power transformers and converter transformers has important technical value and social and economic benefits. Usually, the windings are long-term subjected to complex electromagnetic, thermal stress and mechanical vibration, which are prone to hidden dangers such as deformation and displacement. Traditional off-line detection means have monitoring blind spots and are difficult to capture dynamic defects in time. The on-line diagnosis technology realizes state evaluation by collecting the operating characteristic parameters of the transformer in real time and combining intelligent algorithms, which can significantly improve the hidden danger warning ability, and can also promote the digital transformation of the power equipment operation and maintenance mode from "planned maintenance" to "condition-based maintenance", providing key equipment reliability guarantee for the new energy high-penetration power grid, and having significant power grid safety benefits and low-carbon economic value.

[0004] The patent "A Three-Phase Transformer Fault Detection Method and System (Publication No.: CN115792733A)" calculates the secondary parameters by measuring the primary voltage and current and combining Kirchhoff's voltage law, and then derives the short-circuit reactance value to judge the winding deformation. This method relies on accurate transformer measurement and is easily affected by electromagnetic interference and wiring methods (such as Y-D connection), resulting in inaccurate winding fault judgment results.

[0005] The patent "A Three-Phase Transformer Winding Deformation Fault Detection Method, Device and System (Publication No.: CN115574710A)" proposes to detect faults by analyzing the changes in the winding-to-ground capacitance, inter-phase capacitance and oscillating wave parameters. This method is sensitive to the operating state of the transformer (such as load fluctuation) and is prone to misjudgment, resulting in inaccurate winding fault judgment results.

[0006] It can be seen that the existing on-line diagnosis methods for winding faults are still easily affected by load fluctuations, electromagnetic interference and wiring methods, etc., and are prone to misjudgment, resulting in poor accuracy of winding fault judgment results. Summary of the Invention

[0007] In view of this, the present invention provides a complex frequency domain on-line diagnosis method and device for power transformer windings, which can realize on-line high-efficiency and high-precision evaluation of the health status of AC transformer and converter transformer windings.

[0008] The specific technical solution of the first embodiment of the present invention is: a complex frequency domain on-line diagnosis method for power transformer windings, the method includes: obtaining a first midpoint voltage vector of the first winding of the power transformer, obtaining a second midpoint voltage vector of the second winding of the power transformer, and obtaining a third midpoint voltage vector of the third winding of the power transformer; obtaining different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector and the third midpoint voltage vector; the different midpoint voltage distance vectors include a first midpoint voltage distance vector between the first winding and the second winding, a second midpoint voltage distance vector between the second winding and the third winding, and a third midpoint voltage distance vector between the first winding and the third winding; obtaining a winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and a preset midpoint voltage distance vector.

[0009] Preferably, the first midpoint voltage vector, the second midpoint voltage vector and the third midpoint voltage vector are obtained by the following formula:

[0010]

[0011] Wherein, is the first midpoint voltage vector; is the second midpoint voltage vector; is the third midpoint voltage vector, is the positive sequence phase voltage vector of the first winding, is the positive sequence phase voltage vector of the second winding reduced to the first winding, is the positive sequence phase voltage vector of the third winding reduced to the first winding, is the positive sequence line current vector of the first winding, is the positive sequence line current vector of the second winding reduced to the first winding, is the positive sequence line current vector of the third winding reduced to the first winding, Z 1z is the reference complex impedance of the first winding, Z 2z is the reference complex impedance of the second winding, Z 3z is the reference complex impedance of the third winding.

[0012] Preferably, the reference complex impedance of the first winding, the reference complex impedance of the second winding, and the reference complex impedance of the third winding are the complex impedances measured by off-line tests of the first winding, the second winding, and the third winding.

[0013] Preferably, the midpoint voltage distance vector is obtained by the following formula:

[0014]

[0015] Where is the midpoint voltage distance vector between the i-th winding and the j-th winding, is the midpoint voltage vector of the i-th winding, is the midpoint voltage vector of the j-th winding.

[0016] Preferably, obtaining the winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and the preset midpoint voltage distance vector includes: comparing the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector with the preset midpoint voltage distance vector threshold respectively; if the amplitude or phase of the target midpoint voltage distance vector is greater than the amplitude or phase of the preset midpoint voltage distance vector threshold, there is a fault in the winding corresponding to the target midpoint voltage distance vector; the target midpoint voltage distance vector is any one of the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector.

[0017] Preferably, the preset midpoint voltage distance vector threshold is determined by the vector deviation of the complex impedance measured by offline test under the rated load.

[0018] The specific technical solution of the second embodiment of the present invention is: a power transformer winding fault complex frequency domain on-line diagnosis system, the system includes: a midpoint voltage acquisition module, a midpoint voltage distance acquisition module, and a diagnosis module; the midpoint voltage acquisition module is used to acquire the first midpoint voltage vector of the first winding of the power transformer, acquire the second midpoint voltage vector of the second winding of the power transformer, and acquire the third midpoint voltage vector of the third winding of the power transformer; the midpoint voltage distance acquisition module is used to acquire different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector, and the third midpoint voltage vector; the different midpoint voltage distance vectors include the first midpoint voltage distance vector between the first winding and the second winding, the second midpoint voltage distance vector between the second winding and the third winding, and the third midpoint voltage distance vector between the first winding and the third winding; the diagnosis module is used to obtain the winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and the preset midpoint voltage distance vector.

[0019] Preferably, the reference complex impedance of the first winding, the reference complex impedance of the second winding, and the reference complex impedance of the third winding are the complex impedances measured by offline tests of the first winding, the second winding, and the third winding.

[0020] The specific technical solution of the third embodiment of the present invention is as follows: A winding fault judgment device for a power transformer, including a memory and a processor, where the memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to execute the steps of the method described in any one of the first embodiments of the present application.

[0021] The specific technical solution of the fourth embodiment of the present invention is as follows: A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor is caused to execute the steps of the method described in any one of the first embodiments of the present application.

[0022] Implementing the embodiments of the present invention will have the following beneficial effects:

[0023] The present invention obtains the midpoint voltage of different windings of a power transformer under a reference complex impedance, and obtains the midpoint voltage distance vector between different windings according to the midpoint voltage. The winding fault diagnosis result of the power transformer is obtained according to the midpoint voltage distance vector and a preset midpoint voltage distance vector. The midpoint voltage in the present invention can reflect the electrical state inside the winding. Compared with the existing detection methods, the midpoint voltage vector is more sensitive to winding faults and is relatively less affected by load fluctuations. At the same time, the acquisition of the midpoint voltage does not require the use of high-precision measuring instruments and is not easily affected by electromagnetic interference and wiring methods. Therefore, the method of diagnosing winding faults according to the midpoint voltage distance obtained is not prone to misjudgment, and the accuracy of the winding fault diagnosis result is improved. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0025] Figure 1 It is a flowchart of the steps of the complex frequency domain online diagnosis method for power transformer winding faults;

[0026] Figure 2 It is a schematic structural diagram of the complex frequency domain online diagnosis system for power transformer winding faults;

[0027] Figure 3 It is an internal structure diagram of a computer device;

[0028] Among them, 201, midpoint voltage acquisition module; 202, midpoint voltage distance acquisition module; 203, diagnosis module. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0030] The terms "first", "second", etc. in the specification, claims and drawings of the present application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or modules is not limited to the listed steps or modules, but optionally further includes steps or modules not listed, or optionally further includes other steps or modules inherent to these processes, methods, products or devices.

[0031] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0032] Please refer to Figure 1 , which is a step flow chart of a complex frequency domain online diagnosis method for a power transformer winding fault in the first embodiment of the present application, to improve the accuracy of the winding fault diagnosis result. The method includes:

[0033] Step 101, obtaining a first midpoint voltage vector of the first winding of the power transformer, obtaining a second midpoint voltage vector of the second winding of the power transformer, and obtaining a third midpoint voltage vector of the third winding of the power transformer;

[0034] Step 102, obtaining different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector and the third midpoint voltage vector; the different midpoint voltage distance vectors include a first midpoint voltage distance vector between the first winding and the second winding, a second midpoint voltage distance vector between the second winding and the third winding, and a third midpoint voltage distance vector between the first winding and the third winding;

[0035] Step 103, obtaining a winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and a preset midpoint voltage distance vector.

[0036] Specifically, the reference complex impedances of the first, second, and third windings of the transformer are obtained through off-line testing, which are 0.26 + 21.15i (Ω), 0.26 - 1.56i (Ω), and 0.26 + 13.73i (Ω) respectively. The positive-sequence voltages and positive-sequence currents of each winding of the power transformer are measured synchronously; the output positive-sequence voltage and output positive-sequence current of the second winding, and the output positive-sequence voltage and output positive-sequence current of the third winding are reduced to the first winding. Among them, the positive-sequence voltage of the first winding is -63.51i (kV), the positive-sequence voltage of the second winding is -0.85 - 22.09i (kV), and after being reduced to the first winding, it is

[0037] -2.43 - 63.1i (kV); the positive-sequence voltage of the third winding is 2.73 - 5.36i (kV), and after being reduced to the first winding, it is -3.31 - 62.97i (kV). The positive-sequence current of the first winding is -17.92 - 119.92i (A), the positive-sequence current of the second winding is -24.97 - 179.59i (A), and after being reduced to the first winding, it is -8.74 - 62.86i (A). The positive-sequence current of the third winding is 219.5 - 563.63i (A), and after being reduced to the first winding, it is -8.76 - 57.07i (A).

[0038] According to the formula The first neutral-point voltage vector is calculated to be -2.532 - 63.1i (kV), the second neutral-point voltage vector is -2.53 - 63.103i (kV), and the third neutral-point voltage vector is -2.529 - 63.105i (kV).

[0039] Furthermore, according to the formula The first neutral-point voltage distance vector is calculated to be -0.001 + 0.003i, its amplitude is 0.0032, and its phase is 108.5°; the second neutral-point voltage distance vector is -0.002 + 0.002i, its amplitude is 0.0028, and its phase is 135°; the third neutral-point voltage distance vector is -0.003 + 0.005i, its amplitude is 0.0058, and its phase is 121°

[0040] The threshold value of the neutral-point voltage distance vector is determined to be -0.001 + 0.003i through the vector deviation of the complex impedance measured by off-line test under the rated load. The amplitude of the threshold value of the neutral-point voltage distance vector is 0.0032, and the phase is 108.5°.

[0041] Compare the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector with a preset midpoint voltage distance vector threshold respectively, where the phase of the second midpoint voltage distance vector is greater than the preset threshold; both the amplitude and phase of the third midpoint voltage distance vector are greater than the preset midpoint voltage distance vector. The second midpoint voltage distance vector corresponds to the second winding and the third winding, and the third midpoint voltage distance vector corresponds to the first winding and the third winding. Therefore, it is determined that there is a fault in the third winding of the transformer.

[0042] The method in this embodiment obtains the midpoint voltage of different windings of a power transformer under a reference complex impedance, obtains the midpoint voltage distance vector between different windings based on the midpoint voltage, and obtains the winding fault diagnosis result of the power transformer according to the midpoint voltage distance vector and the preset midpoint voltage distance vector threshold. The midpoint voltage vector in this embodiment can reflect the electrical state inside the winding. Compared with the existing detection methods, the midpoint voltage vector is more sensitive to winding faults, and is relatively less affected by load fluctuations. At the same time, the midpoint voltage vector is not easily affected by electromagnetic interference and wiring methods. Therefore, the method of diagnosing winding faults based on the midpoint voltage distance obtained from the midpoint voltage is not likely to produce misjudgments, improving the accuracy of the online diagnosis result of winding faults.

[0043] In a specific embodiment, the midpoint voltage distance vector is obtained by using the following formula:

[0044]

[0045] where is the midpoint voltage distance vector between the i-th winding and the j-th winding, is the midpoint voltage vector of the i-th winding, is the midpoint voltage vector of the j-th winding.

[0046] In a specific embodiment, the preset midpoint voltage distance vector threshold is determined by the vector deviation of the complex impedance measured through off-line tests under rated load. Specifically, this method improves the accuracy of fault diagnosis. By measuring the complex impedance through off-line tests and calculating the vector deviation under rated load, the electrical state inside the winding can be more accurately reflected. Compared with traditional detection methods, this method is more sensitive to winding faults and can capture fault signals at an early stage, thus avoiding the further development of faults. Secondly, this method enhances the reliability of the diagnostic results. The preset midpoint voltage distance vector threshold is obtained based on a large amount of off-line test data and empirical analysis, and has high accuracy and reliability. When the measured vector deviation exceeds this threshold, it can be considered that there is a fault in the winding, reducing the possibility of misjudgment. In addition, this method also reduces the diagnostic cost. The process of measuring the complex impedance through off-line tests is relatively simple and does not rely on high-precision real-time measurement instruments, reducing the detection cost. At the same time, the preset threshold can be applied to different types of windings, with wide applicability, further reducing the diagnostic cost. Finally, this method provides strong support for the prevention and maintenance of winding faults. By regularly measuring the complex impedance through off-line tests and calculating the vector deviation, potential faults in the winding can be detected in time, providing a decision basis for repair and replacement to ensure the safe and stable operation of the power system.

[0047] In a specific embodiment, please refer to Figure 2 , which is a schematic structural diagram of a complex frequency domain on-line diagnosis system for power transformer winding faults provided by the second embodiment of the present application. The system includes: a midpoint voltage acquisition module 201, a midpoint voltage distance acquisition module 202, and a diagnosis module 203; the midpoint voltage acquisition module 201 is used to acquire the first midpoint voltage vector of the first winding of the power transformer, acquire the second midpoint voltage vector of the second winding of the power transformer, and acquire the third midpoint voltage vector of the third winding of the power transformer; the midpoint voltage distance acquisition module 202 is used to acquire different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector, and the third midpoint voltage vector; the different midpoint voltage distance vectors include a first midpoint voltage distance vector between the first winding and the second winding, a second midpoint voltage distance vector between the second winding and the third winding, and a third midpoint voltage distance vector between the first winding and the third winding; the diagnosis module 203 is used to obtain the winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and the preset midpoint voltage distance vector.

[0048] The system in this embodiment obtains the neutral point voltage of different windings of a power transformer under the reference complex impedance, and obtains the neutral point voltage distance vector between different windings according to the neutral point voltage. The winding fault diagnosis result of the power transformer is obtained based on the comparison between the neutral point voltage distance vector and the preset neutral point voltage distance vector threshold. The neutral point voltage vector in this embodiment can reflect the electrical state inside the winding. Compared with the existing detection methods, the neutral point voltage vector is more sensitive to winding faults, less affected by load fluctuations, and not easily affected by electromagnetic interference and wiring methods. Therefore, the method of diagnosing winding faults based on the neutral point voltage distance obtained is not prone to misjudgment, improving the accuracy of the on-line diagnosis result of winding faults.

[0049] In a specific embodiment, the reference complex impedances of the first winding, the second winding, and the third winding are the complex impedances measured by off-line tests of the first winding, the second winding, and the third winding.

[0050] In a specific embodiment, obtaining the winding fault diagnosis result of the power transformer according to the different neutral point voltage distance vectors and the preset neutral point voltage distance vector includes: comparing the first neutral point voltage distance vector, the second neutral point voltage distance vector, and the third neutral point voltage distance vector with the preset neutral point voltage distance vector threshold respectively; if the amplitude or phase of the target neutral point voltage distance vector is greater than the amplitude or phase of the preset neutral point voltage distance vector threshold, there is a fault in the winding corresponding to the target neutral point voltage distance vector; the target neutral point voltage distance vector is any one of the first neutral point voltage distance vector, the second neutral point voltage distance vector, and the third neutral point voltage distance vector.

[0051] Specifically, the reference complex impedances of the first winding, the second winding, and the third winding of the transformer are obtained through off-line tests, which are 0.26 + 21.15i (Ω), 0.26 - 1.56i (Ω), and 0.26 + 13.73i (Ω) respectively. The positive sequence voltages and positive sequence currents of each winding of the power transformer are measured synchronously; the output positive sequence voltage and output positive sequence current of the second winding, and the output positive sequence voltage and output positive sequence current of the third winding are reduced to the first winding. Among them, the positive sequence voltage of the first winding is -63.51i (kV), and the positive sequence voltage of the second winding is -0.85 - 22.09i (kV), and after being reduced to the first winding, it is

[0052] -2.43 - 63.1i (kV); the positive-sequence voltage of the third winding is 2.73 - 5.36i (kV), and after being reduced to the first winding, it is -3.31 - 62.97i (kV). The positive-sequence current of the first winding is -17.92 - 119.92i (A), the positive-sequence current of the second winding is -24.97 - 179.59i (A), and after being reduced to the first winding, it is -8.74 - 62.86i (A). The positive-sequence current of the third winding is 219.5 - 563.63i (A), and after being reduced to the first winding, it is -8.76 - 57.07i (A).

[0053] According to the formula The first midpoint voltage vector is calculated to be -2.532 - 63.1i (kV), the second midpoint voltage vector is -2.53 - 63.103i (kV), and the third midpoint voltage vector is -2.529 - 63.105i (kV).

[0054] Furthermore, according to the formula The first midpoint voltage distance vector is calculated to be -0.001 + 0.003i, its amplitude is 0.0032, and its phase is 108.5°; the second midpoint voltage distance vector is -0.002 + 0.002i, its amplitude is 0.0028, and its phase is 135°; the third midpoint voltage distance vector is -0.003 + 0.005i, its amplitude is 0.0058, and its phase is 121°

[0055] The threshold of the midpoint voltage distance vector is determined to be -0.001 + 0.003i based on the vector deviation of the complex impedance measured by off-line tests under rated load. The amplitude of the threshold of the midpoint voltage distance vector is 0.0032 and the phase is 108.5°.

[0056] Compare the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector with the preset threshold of the midpoint voltage distance vector respectively. Among them, the phase of the second midpoint voltage distance vector is greater than the preset threshold; both the amplitude and phase of the third midpoint voltage distance vector are greater than the preset midpoint voltage distance vector. The second midpoint voltage distance vector corresponds to the second winding and the third winding, and the third midpoint voltage distance vector corresponds to the first winding and the third winding. Therefore, it is judged that there is a fault in the third winding of the transformer.

[0057] In a specific embodiment, the third embodiment of the present application provides a winding fault judgment device for a power transformer, including a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is caused to execute the steps of the method according to any one of the first embodiments of the present application. The device in this embodiment obtains the midpoint voltage of different windings of the power transformer under the reference complex impedance, and obtains the midpoint voltage distance vector between different windings according to the midpoint voltage, and obtains the winding fault diagnosis result of the power transformer according to the midpoint voltage distance vector and the preset midpoint voltage distance vector threshold. The midpoint voltage vector in this embodiment can reflect the electrical state inside the winding. Compared with the existing detection methods, the midpoint voltage vector is more sensitive to winding faults, and is relatively less affected by load fluctuations. At the same time, the midpoint voltage vector is not easily affected by electromagnetic interference and wiring methods. Therefore, the method of diagnosing winding faults according to the midpoint voltage distance obtained from the midpoint voltage is not likely to produce misjudgments, improving the accuracy of the online diagnosis result of winding faults.

[0058] In a specific embodiment, the fourth embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the steps of the method according to any one of the first embodiments of the present application. The storage medium in this embodiment obtains the midpoint voltage of different windings of a power transformer under a reference complex impedance, and obtains a midpoint voltage distance vector between different windings according to the midpoint voltage. A winding fault diagnosis result of the power transformer is obtained according to the midpoint voltage distance vector and a preset midpoint voltage distance vector threshold. As an advanced detection technology, the midpoint voltage has shown unique advantages in the field of winding state monitoring and fault diagnosis. It can not only effectively reflect the electrical state inside the winding, but also, compared with traditional detection methods, the sensitivity of the midpoint voltage vector to winding faults is significantly improved. This characteristic means that when early faults or minor abnormalities occur in the winding, the midpoint voltage can capture these changes, thus providing the possibility for early warning and timely maintenance. In addition, the midpoint voltage also shows good stability in practical applications. Even when the load fluctuates greatly, the change in the midpoint voltage is relatively small, which further enhances its reliability in winding fault diagnosis. This characteristic makes the midpoint voltage an ideal tool that can maintain accurate diagnosis results under various working conditions. It is worth mentioning that the process of obtaining the midpoint voltage is relatively simple and does not require relying on high-precision measuring instruments. This not only reduces the detection cost, but also makes the midpoint voltage technology easier to promote and popularize in practical applications. At the same time, the midpoint voltage is not easily affected by electromagnetic interference and wiring methods, which further improves the accuracy and stability of its diagnosis results. Based on these advantages of the midpoint voltage, the method of using the midpoint voltage distance for winding fault diagnosis has achieved remarkable results in practical applications. This method not only reduces the possibility of misjudgment, but also greatly improves the accuracy of the winding fault diagnosis result.

[0059] Figure 3 shows the internal structure diagram of a computer device in an embodiment. This computer device can specifically be a terminal or a server. Please refer to Figure 3 , this computer device includes a processor, a memory, etc. connected through a system bus. Among them, the memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of this computer device stores an operating system and can also store a computer program. When the computer program is executed by the processor, the processor can be caused to implement the method in this embodiment. The internal memory can also store a computer program. When the computer program is executed by the processor, the processor can be caused to execute the method in this embodiment. Those skilled in the art can understand, Figure 3The structure shown is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0060] The above embodiments only represent several implementation manners of this application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of this application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of the patent of this application shall be subject to the appended claims.

[0061] The above is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A complex frequency domain online diagnosis method for power transformer winding faults, characterized in that The method includes: Obtaining a first midpoint voltage vector of a first winding of a power transformer, obtaining a second midpoint voltage vector of a second winding of the power transformer, and obtaining a third midpoint voltage vector of a third winding of the power transformer; Obtaining different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector, and the third midpoint voltage vector; the different midpoint voltage distance vectors include a first midpoint voltage distance vector between the first winding and the second winding, a second midpoint voltage distance vector between the second winding and the third winding, and a third midpoint voltage distance vector between the first winding and the third winding; Obtaining a winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and a preset midpoint voltage distance vector.

2. The online diagnosis method for the complex frequency domain of the power transformer winding fault according to claim 1, characterized in that The first midpoint voltage vector, the second midpoint voltage vector, and the third midpoint voltage vector are obtained by using the following formula: wherein, is the first midpoint voltage vector; is the second midpoint voltage vector; is the third midpoint voltage vector, is the positive-sequence phase voltage vector of the first winding, is the positive-sequence phase voltage vector of the second winding referred to the first winding, is the positive-sequence phase voltage vector of the third winding referred to the first winding, is the positive-sequence line current vector of the first winding, is the positive-sequence line current vector of the second winding referred to the first winding, is the positive-sequence line current vector of the third winding referred to the first winding, Z 1z is the reference complex impedance of the first winding, Z 2z is the reference complex impedance of the second winding, Z 3z is the reference complex impedance of the third winding.

3. The online diagnosis method for complex frequency domain of power transformer winding faults according to claim 2, characterized in that The reference complex impedances of the first winding, the second winding, and the third winding are the complex impedances measured by off-line tests of the first winding, the second winding, and the third winding.

4. The online diagnosis method for the complex frequency domain of power transformer winding faults according to claim 1, characterized in that The midpoint voltage distance vector is obtained by using the following formula: wherein, is the midpoint voltage distance vector between the i-th winding and the j-th winding, is the midpoint voltage vector of the i-th winding, is the midpoint voltage vector of the j-th winding.

5. The online diagnosis method for the complex frequency domain of the power transformer winding fault according to claim 1, wherein The obtaining the winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and the preset midpoint voltage distance vector includes: Comparing the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector with a preset midpoint voltage distance vector threshold respectively; If the amplitude or phase of a target midpoint voltage distance vector is greater than the amplitude or phase of the preset midpoint voltage distance vector threshold, there is a fault in the winding corresponding to the target midpoint voltage distance vector; the target midpoint voltage distance vector is any one of the first midpoint voltage distance vector, the second midpoint voltage distance vector, and the third midpoint voltage distance vector.

6. The online diagnosis method for the complex frequency domain of the power transformer winding fault according to claim 5, characterized in that, The preset midpoint voltage distance vector threshold is determined by the vector deviation of the complex impedance measured by off-line tests under the rated load.

7. A complex frequency domain on-line diagnosis system for power transformer windings faults, characterized in that, The system includes: a midpoint voltage acquisition module, a midpoint voltage distance acquisition module, and a diagnosis module; The midpoint voltage acquisition module is configured to obtain a first midpoint voltage vector of a first winding of a power transformer, obtain a second midpoint voltage vector of a second winding of the power transformer, and obtain a third midpoint voltage vector of a third winding of the power transformer; The midpoint voltage distance acquisition module is configured to obtain different midpoint voltage distance vectors between different windings according to the first midpoint voltage vector, the second midpoint voltage vector, and the third midpoint voltage vector; the different midpoint voltage distance vectors include a first midpoint voltage distance vector between the first winding and the second winding, a second midpoint voltage distance vector between the second winding and the third winding, and a third midpoint voltage distance vector between the first winding and the third winding; The diagnosis module is configured to obtain a winding fault diagnosis result of the power transformer according to the different midpoint voltage distance vectors and a preset midpoint voltage distance vector.

8. The online diagnosis system for complex frequency domain of power transformer winding faults according to claim 7, characterized in that, The reference complex impedances of the first winding, the second winding, and the third winding are the complex impedances measured by off-line tests of the first winding, the second winding, and the third winding.

9. A winding fault judgment device for a power transformer, comprising a memory and a processor, characterized in that, The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 6.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 6.

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