Transformer winding fault detection method and system based on frequency response and medium

Abstract

The embodiment of the invention relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method and system based on frequency response and a medium, and the method comprises the steps: determining the equivalent inductance and equivalent capacitance of a transformer winding; and calculating a first-order grounding coefficient of driving point admittance by using the peak frequency and the valley frequency when the neutral point is grounded, and calculating a first-order open-circuit coefficient by using the peak frequency and the valley frequency when the neutral point is open-circuit. A first difference function is constructed through the equivalent inductance, the scaling rate and the first-order grounding coefficient, and a second difference function is constructed through the equivalent capacitance and the first-order open circuit coefficient. And fault detection of the transformer winding is carried out according to a comparison condition between fluctuation of the first difference function and the second difference function and a preset threshold value, and early sensitive detection is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer fault detection, and in particular to a transformer winding fault detection method, system and medium based on frequency response. Background Art

[0002] As a key component of the power system, the reliability of transformer windings directly affects the stable operation of the power system. However, due to long-term operation, environmental factors, and design flaws, transformer windings are prone to premature failure, posing a potential threat to the safe operation of the power grid.

[0003] Traditional detection methods rely primarily on scheduled power outages and offline testing, which not only increases maintenance costs but also impacts the continuity of power supply. Furthermore, traditional detection methods lack accuracy in early fault diagnosis, failing to respond more sensitively to transformer winding faults or diagnose the severity of the fault. With the increasing safety and reliability requirements of modern power systems, the development of an efficient, non-invasive method that can provide early warning of transformer winding faults has become increasingly important. Summary of the Invention

[0004] Based on this, it is necessary to address the above problems and propose a transformer winding fault detection method, system and medium based on frequency response.

[0005] A method for detecting transformer winding faults based on frequency response, the method comprising: The equivalent inductance and equivalent capacitance of the transformer winding are determined.

[0006] The first-order grounding coefficient of the driving point admittance is determined according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded.

[0007] The first-order open-circuit coefficient of the driving point admittance is determined according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open-circuited.

[0008] A first difference function is determined according to the equivalent inductance and the first-order grounding coefficient, and a second difference function is determined according to the equivalent capacitance and the first-order open-circuit coefficient.

[0009] Fault detection of the transformer winding is performed based on a comparison between fluctuations of the first difference function and the second difference function and a preset threshold.

[0010] The determining of the first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded specifically includes: The peak frequency and the valley frequency when the neutral point of the transformer winding is grounded are collected.

[0011] according to Determine the first-order grounding coefficient of the driving point admittance, where is the first-order grounding coefficient of the driving point admittance, is the peak frequency when the neutral point is grounded, It is the valley frequency when the neutral point is grounded.

[0012] The first-order open-circuit coefficient of the driving point admittance is determined according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open, specifically including: The peak frequency and the valley frequency when the neutral point of the transformer winding is open are collected.

[0013] according to Determine the first-order open-loop coefficient of the driving-point admittance, where is the first-order open-circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, It is the valley frequency when the neutral point is open.

[0014] The determining of the first difference function based on the equivalent inductance and the first-order grounding coefficient, and the determining of the second difference function based on the equivalent capacitance and the first-order open-circuit coefficient, specifically includes: according to Determine a first difference function, where is the first difference function, is the equivalent inductance, For the preset zoom ratio, is the first-order grounding coefficient of the driving point admittance.

[0015] according to Determine a second difference function, where is the second difference function, is the equivalent capacitance, is the first-order open-circuit coefficient of the driving-point admittance.

[0016] The step of performing fault detection on the transformer winding according to a comparison between fluctuations of the first difference function and the second difference function and a preset threshold value specifically includes: Determine whether the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, where the preset threshold is a first amplitude threshold or a first frequency threshold.

[0017] If the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, the transformer winding fails.

[0018] If the fluctuation amplitude of the first difference function and the second difference function is less than or equal to a preset threshold, the transformer winding does not occur.

[0019] The determining of the equivalent inductance and equivalent capacitance of the transformer winding specifically includes: A current excitation is applied to the transformer winding, wherein the current excitation is determined by geometrically scaling the normal operating current of the transformer winding at a preset scaling rate.

[0020] The self-inductance of the transformer winding is determined according to the current excitation and the self-inductance coefficient of the transformer winding, and the mutual inductance of the transformer winding is determined according to the current excitation and the mutual inductance coefficient of the transformer winding.

[0021] An equivalent inductance is determined according to the self-inductance and the mutual inductance.

[0022] The series capacitance and ground capacitance of the transformer winding are obtained, and an equivalent capacitance is determined according to the series capacitance and the ground capacitance.

[0023] The step of determining the self-inductance of the transformer winding according to the current excitation and the self-inductance coefficient of the transformer winding, and determining the mutual inductance of the transformer winding according to the current excitation and the mutual inductance coefficient of the transformer winding, specifically includes: according to Get the self-inductance of the transformer winding, where is the magnetic permeability, is the number of coil turns, is the cross-sectional area of ​​the coil, is the length of the coil.

[0024] according to Determine the self-inductance of the transformer winding, where For transformer The self-inductance of a winding, For the The self-inductance of the winding, For current excitation.

[0025] according to Determine the mutual inductance of the transformer windings, where For the The first winding and the The mutual inductance of the windings, For the The self-inductance of the winding, is the self-inductance coefficient of the j-th winding, and k is the coupling coefficient.

[0026] according to Determine the mutual inductance of the transformer windings, where For transformer The first winding and the The mutual inductance between the windings, For the The first winding and the The mutual inductance of the windings, For current excitation.

[0027] The determining of the equivalent inductance according to the self-inductance and the mutual inductance specifically includes: according to Determine the equivalent inductance, where is the equivalent inductance, The connection between the i-th winding and the i-th winding of the transformer The mutual inductance between the windings, is the self-inductance of the transformer's first winding.

[0028] The determining of the equivalent capacitance according to the series capacitance and the ground capacitance specifically includes: according to Determine the equivalent capacitance, where is the equivalent capacitance, is the series capacitor, is the grounding capacitor.

[0029] The method further comprises: The fault level of the transformer winding is determined based on a comparison between the fluctuation of the first difference function and / or the second difference function and a preset fault level judgment condition.

[0030] The step of determining the fault level of the transformer winding according to the comparison between the fluctuation of the first difference function and / or the second difference function and the preset fault level judgment condition specifically includes: Determining that the fault level of the transformer winding is a primary fault when the fluctuation amplitude of the first difference function and / or the second difference function reaches a second amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a second frequency threshold; It is determined that the fluctuation amplitude of the first difference function and / or the second difference function reaches a third amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a third frequency threshold, the fault level of the transformer winding is a secondary fault.

[0031] A transformer winding fault detection system based on frequency response, the system comprising: The equivalent inductance and equivalent capacitance acquisition module is used to determine the equivalent inductance and equivalent capacitance of the transformer winding.

[0032] The module for determining the first-order grounding coefficient of the driving point admittance is used to determine the first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded.

[0033] The first-order open-circuit coefficient determination module of the driving point admittance is used to determine the first-order open-circuit coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open.

[0034] The first difference function and second difference function determination module is used to determine the first difference function according to the equivalent inductance and the first-order grounding coefficient, and to determine the second difference function according to the equivalent capacitance and the first-order open circuit coefficient.

[0035] A fault detection module is used to perform fault detection on the transformer winding based on a comparison between the fluctuations of the first difference function and the second difference function and a preset threshold.

[0036] A computer-readable storage medium stores a computer program, which, when executed by a processor, causes the processor to perform the steps of the above method.

[0037] The embodiments of the present invention have the following beneficial effects: The present invention first obtains the equivalent inductance and equivalent capacitance of the transformer winding. Furthermore, the first-order grounding coefficient of the driving point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is grounded, and the first-order open-circuit coefficient of the driving point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is open. The first-order grounding coefficient is used as the actual measured approximate inductance, and the first-order open-circuit coefficient is used as the actual measured approximate capacitance. Finally, a first difference function is determined based on the equivalent inductance and the first-order grounding coefficient, and a second difference function is determined based on the equivalent capacitance and the first-order open-circuit coefficient. The first difference function can be used to represent the variation characteristics of the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function can be used to represent the variation characteristics of the ideal equivalent capacitance and the actual measured approximate capacitance. Therefore, transformer winding fault detection is performed based on the comparison of the fluctuations of the first difference function and the second difference function with a preset threshold.

[0038] This invention analyzes key electrical parameters of the transformer winding, such as its equivalent inductance and capacitance, and combines them with the transformer winding's frequency response characteristics under different operating conditions (frequency response is more sensitive than current). This approach avoids the possibility that minor winding deformation may result in no or only slight current changes. By performing a difference function analysis on the first-order ground coefficient and first-order open-circuit coefficient of the driving-point admittance (approximately equivalent inductance and capacitance, respectively) with the ideal equivalent inductance and capacitance measured in the non-operating state, it can detect potential fault precursors early, providing a reliable basis for implementing preventive maintenance measures. Furthermore, by considering not only the transformer winding's electrical characteristics but also indirect mechanical and thermal characteristics, the invention enables a more comprehensive assessment of its health. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] in: Figure 1 A schematic flow chart of an embodiment of a transformer winding fault detection method based on frequency response provided by the present invention; Figure 2 A schematic flow chart of another embodiment of a transformer winding fault detection method based on frequency response provided by the present invention; Figure 3 A flow chart of another embodiment of a transformer winding fault detection method based on frequency response provided by the present invention; Figure 4 A schematic structural diagram of an embodiment of a transformer winding fault detection system based on frequency response provided by the present invention; Figure 5 This is a schematic structural diagram of an embodiment of the medium provided by the present invention. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] like Figure 1 As shown, Figure 1A method for detecting a transformer winding fault based on frequency response is provided by the present invention. The method comprises: S101: Determine the equivalent inductance and equivalent capacitance of the transformer winding.

[0043] In one implementation scenario, in order to detect the transformer, it is necessary to apply current excitation to the transformer winding. The current excitation is determined by geometrically scaling the normal operating current of the transformer winding at a preset scaling rate.

[0044] Furthermore, the self-inductance of the transformer winding is determined based on the current excitation and the self-inductance coefficient of the transformer winding, and the mutual inductance of the transformer winding is determined based on the current excitation and the mutual inductance coefficient of the transformer winding.

[0045] Specifically, the self-inductance of the transformer winding is determined according to the following formula: ; in, For transformer The self-inductance of a winding, For the The self-inductance of the winding, is current excitation; Furthermore, the mutual inductance of the transformer windings is determined according to the self-inductance of different transformer windings and the degree of magnetic coupling between the windings.

[0046] Determine the mutual inductance of the transformer windings using the following formula: ; in, For transformer The first winding and the The mutual inductance between the windings, For the The first winding and the The mutual inductance of the windings, For current excitation.

[0047] Furthermore, the equivalent inductance is determined based on the self-inductance and the mutual inductance.

[0048] Specifically, the equivalent inductance is determined according to the following formula: ; in, is the equivalent inductance, The connection between the i-th winding and the i-th winding of the transformer The mutual inductance between the windings, is the self-inductance of the transformer's first winding.

[0049] Furthermore, the series capacitance and ground capacitance of the transformer winding are obtained, and the equivalent capacitance is determined based on the series capacitance and ground capacitance. Specifically, the equivalent capacitance is determined according to the following formula: ; in, is the equivalent capacitance, is the series capacitor, is the grounding capacitor.

[0050] S102: Determine a first-order grounding coefficient of the driving point admittance according to a peak frequency and a valley frequency when the neutral point of the transformer winding is grounded.

[0051] S103: Determine a first-order open-circuit coefficient of the driving point admittance according to a peak frequency and a valley frequency when the neutral point of the transformer winding is open-circuited.

[0052] In an implementation scenario, the driving point admittance of a transformer refers to the equivalent admittance seen from one side of the transformer, reflecting the response characteristics of the port on that side to the current. The driving point admittance characterizes the coefficient relationship between the input and output of the transformer winding. Its first-order grounding coefficient Can be approximately equal to the equivalent inductance , first-order open-circuit coefficient Can be approximately equal to the equivalent capacitance Therefore, the first-order grounding coefficient can be As the approximate inductance actually measured, the first-order open-circuit coefficient As an approximation of the actual measured capacitance, the sensitivity of fault detection can be improved by incorporating the frequency response into the calculation.

[0053] To determine the first-order grounding coefficient and first-order open-circuit coefficient of the driving-point admittance, first use a frequency meter or impedance meter to collect the peak and valley frequencies when the transformer's neutral point is grounded, and when the neutral point is open. The transformer's neutral point is the point connected to the winding end, typically used for grounding or connecting protective equipment. The selection of the neutral point is closely related to the winding connection method.

[0054] Furthermore, the first-order grounding coefficient of the driving point admittance is determined according to the following formula: ; in, is the first-order grounding coefficient of the driving point admittance, is the peak frequency when the neutral point is grounded, It is the valley frequency when the neutral point is grounded.

[0055] The first-order open-circuit coefficient of the driving point admittance is determined according to the following formula: ; in, is the first-order open-circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, It is the valley frequency when the neutral point is open.

[0056] S104: Determine a first difference function according to the equivalent inductance and the first-order grounding coefficient, and determine a second difference function according to the equivalent capacitance and the first-order open-circuit coefficient.

[0057] In one implementation scenario, the first difference function is used to represent the variation characteristics between the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function is used to represent the variation characteristics between the ideal equivalent capacitance and the actual measured approximate capacitance. The first difference function is determined according to the following formula: ; in, is the first difference function, is the equivalent inductance, For the preset zoom ratio, is the first-order grounding coefficient of the driving point admittance.

[0058] The second difference function is determined according to the following formula: ; in, is the second difference function, is the equivalent capacitance, is the first-order open-circuit coefficient of the driving-point admittance.

[0059] S105: Perform transformer winding fault detection based on a comparison between the fluctuations of the first difference function and the second difference function and a preset threshold.

[0060] In one implementation scenario, transformer winding fault detection is performed based on the comparison of the fluctuation of the first difference function and the second difference function with a preset threshold. The first difference function is used to represent the change characteristics of the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function is used to represent the change characteristics of the ideal equivalent capacitance and the actual measured approximate capacitance. When the winding has faults such as axial deformation or inter-turn short circuit, its equivalent inductance will be significantly changed. When the winding has faults such as radial deformation, the equivalent capacitance will change significantly. Therefore, it is possible to determine whether the winding has a fault by calculating the change characteristics of the ideal equivalent inductance and ideal equivalent capacitance and the actual measured approximate inductance and the actual measured approximate capacitance.

[0061] Specifically, when the transformer operates normally, the values ​​of the first difference function and the second difference function should be stable. When the first difference function and the second difference function fluctuate significantly, it can be considered that the transformer winding has a fault.

[0062] As can be seen from the above description, the present invention first obtains the equivalent inductance and equivalent capacitance of the transformer winding. Furthermore, the first-order grounding coefficient of the driving-point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is grounded, and the first-order open-circuit coefficient of the driving-point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is open. The first-order grounding coefficient is used as the actual measured approximate inductance, and the first-order open-circuit coefficient is used as the actual measured approximate capacitance. Finally, a first difference function is determined based on the equivalent inductance and the first-order grounding coefficient, and a second difference function is determined based on the equivalent capacitance and the first-order open-circuit coefficient. The first difference function can be used to represent the variation characteristics of the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function can be used to represent the variation characteristics of the ideal equivalent capacitance and the actual measured approximate capacitance. Therefore, transformer winding fault detection is performed based on the comparison of the fluctuations of the first and second difference functions with a preset threshold.

[0063] This invention analyzes key electrical parameters of the transformer winding, such as its equivalent inductance and capacitance, and combines them with the transformer winding's frequency response characteristics under different operating conditions (frequency response is more sensitive than current). This approach avoids the possibility that minor winding deformation may result in no or only slight current changes. By performing a difference function analysis on the first-order ground coefficient and first-order open-circuit coefficient of the driving-point admittance (approximately equivalent inductance and capacitance, respectively) with the ideal equivalent inductance and capacitance measured in the non-operating state, it can detect potential fault precursors early, providing a reliable basis for implementing preventive maintenance measures. Furthermore, by considering not only the transformer winding's electrical characteristics but also indirect mechanical and thermal characteristics, the invention enables a more comprehensive assessment of its health.

[0064] like Figure 2 As shown, Figure 2 A method for detecting a transformer winding fault based on frequency response is provided by the present invention. The method comprises: S201: applying current excitation to the transformer winding, where the current excitation is determined by geometrically scaling the normal operating current of the transformer winding at a preset scaling rate.

[0065] In one implementation scenario, to test a transformer, it is necessary to apply current excitation to its windings so that the self-inductance and mutual inductance of the transformer windings can be calculated under this current excitation. The self-inductance and mutual inductance of the transformer windings can be calculated simultaneously with a single application of the current excitation, or the self-inductance and mutual inductance of the transformer windings can be calculated separately by applying the same current excitation twice.

[0066] Among them, the current excitation can be determined by scaling the normal working current of the transformer winding at a preset scaling rate; specifically, since the voltage and current during actual operation are too large to be controlled, the current can be appropriately scaled during data acquisition and detection to prevent the distortion of the measurement data caused by the current being too large. For example, the scaling rate can be Since the current excitation is scaled here, the scaling factor needs to be substituted into the subsequent calculation process to prevent inaccurate data.

[0067] S202: Determine the self-inductance of the transformer winding according to the current excitation and the self-inductance coefficient of the transformer winding, and determine the mutual inductance of the transformer winding according to the current excitation and the mutual inductance coefficient of the transformer winding.

[0068] In one implementation scenario, when determining the self-inductance When the current excitation condition is given, the calculation is performed. The current excitation is determined by scaling the normal operating current of the transformer winding with a preset scaling ratio (assuming the preset scaling ratio is ), calculate the self-inductance according to the following formula: ; in, For transformer The self-inductance of a winding, For the The self-inductance of the winding, , Indicates the total number of windings, The current excitation is determined by scaling the normal operating current of the transformer winding at a preset scaling rate. Indicates the rate of change of current. Through magnetic permeability , coil turns , cross-sectional area of ​​the coil , coil length Calculation results: ; in, is the magnetic permeability, N is the number of coil turns, is the cross-sectional area of ​​the coil, is the length of the coil.

[0069] In determining mutual inductance When giving different windings the same current excitation conditions as when determining the self-inductance, the mutual inductance is calculated according to the following formula: ; in, For transformer The first winding and the The mutual inductance between the windings, is the current excitation, Indicates the The first winding and the The mutual inductance of the windings, For the The first winding and the The mutual inductance of the windings, It can be determined based on the self-inductance of different transformer windings and the degree of magnetic coupling between the windings, as shown in the following formula: ; Where k is the coupling coefficient, which is 1. For transformer The self-inductance of a winding, For transformer The self-inductance of a winding.

[0070] It should be noted that self-inductance refers to the electromotive force generated by a transformer winding due to current changes. That is, when the current through a winding changes, the winding itself will induce an electromotive force in the opposite direction due to the changing magnetic field. This phenomenon is called self-inductance. Mutual inductance refers to the phenomenon between two adjacent windings. When the current in one winding changes, it generates a changing magnetic field, which in turn induces an electromotive force in the other adjacent winding. This phenomenon is called mutual inductance. The equivalent inductance under ideal conditions can be calculated based on self-inductance and mutual inductance, and the equivalent capacitance under ideal conditions can be calculated based on series capacitance and ground capacitance.

[0071] S203: Determine equivalent inductance according to self-inductance and mutual inductance.

[0072] In one implementation scenario, only the mutual inductance between two adjacent windings is considered when calculating the equivalent inductance. It can be calculated by the following formula: ; in, is the equivalent inductance, The i-th winding and the The mutual inductance between the windings, is the self-inductance of the transformer's first winding.

[0073] In addition, since the main purpose of this embodiment is to detect early transformer faults, its goal is qualitative rather than quantitative, and any fault in any winding will cause a significant change in the inductance data characteristics. Therefore, in another optional implementation, in order to simplify the difficulty of data analysis, only the unidirectional mutual inductance effect can be considered when calculating the equivalent inductance, so as to facilitate subsequent data processing and will not affect the implementation effect of fault detection. For example, when calculating the equivalent inductance, it is set that the first inductance is only affected by the mutual inductance between the first winding and the second winding, the second inductance is only affected by the mutual inductance between the second winding and the third winding, and so on. Therefore, the equivalent inductance can be calculated by the following simplified formula: ; in, is the equivalent inductance, The i-th winding and the The mutual inductance between the windings, is the self-inductance of the transformer's first winding.

[0074] It should be noted that in practical applications, the method for calculating the equivalent inductance can be selected based on actual needs.

[0075] S204: Obtain the series capacitance and ground capacitance of the transformer winding, and determine the equivalent capacitance according to the series capacitance and ground capacitance.

[0076] In one implementation scenario, the series capacitance and ground capacitance of the transformer winding are first obtained. Specifically, the series capacitance is calculated using a parallel plate capacitance model. Calculate as shown below: ; in, is the series capacitance of the transformer winding, is the dielectric constant of vacuum, is the relative dielectric constant of the medium, For the The first winding and the The effective overlapping area between the windings is is the thickness of the insulation layer between turns. This formula only considers the series capacitance between two adjacent windings.

[0077] It should be noted that the series capacitor uses interlayer capacitance, which refers to the capacitance between layers of the transformer winding. Specifically, due to the small interturn capacitance, the present invention does not calculate the interturn capacitance, but only the interlayer capacitance, which refers to the capacitance between different windings of the transformer.

[0078] Calculating ground capacitance When the winding is approximated as a coaxial cylindrical model, the grounding capacitance It can be calculated by the following formula: ; in, is the grounding capacitance of the transformer winding, For the The length of the winding, is the outer diameter of the winding, is the inner diameter of the winding.

[0079] Furthermore, the equivalent capacitance is determined based on the series capacitance and the ground capacitance. Ideally, the equivalent capacitance is calculated using the following formula: ; in, is the equivalent capacitance, is the series capacitor, is the grounding capacitor.

[0080] S205: Determine a first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded.

[0081] S206: Determine a first-order open-circuit coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open-circuited.

[0082] In one implementation scenario, the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded, and the peak frequency and the valley frequency when the neutral point of the transformer winding is open, are collected.

[0083] Furthermore, the first-order grounding coefficient of the driving point admittance is determined according to the following formula: ; in, is the first-order grounding coefficient of the driving point admittance, is the peak frequency when the neutral point is grounded, It is the valley frequency when the neutral point is grounded.

[0084] The first-order open-circuit coefficient of the driving point admittance is determined according to the following formula: ; in, is the first-order open-circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, It is the valley frequency when the neutral point is open.

[0085] S207: Determine a first difference function according to the equivalent inductance, the preset scaling factor, and the first-order grounding coefficient, and determine a second difference function according to the equivalent capacitance and the first-order open-circuit coefficient.

[0086] In one implementation scenario, the first difference function is determined according to the following formula: ; in, is the first difference function, is the equivalent inductance, For the preset zoom ratio, is the first-order grounding coefficient of the driving point admittance.

[0087] The second difference function is determined according to the following formula: ; in, is the second difference function, is the equivalent capacitance, is the first-order open-circuit coefficient of the driving-point admittance.

[0088] S208: Determine whether the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, where the preset threshold is a first amplitude threshold or a first frequency threshold.

[0089] S2081: If the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, the transformer winding fails.

[0090] S2082: If the fluctuation amplitudes of the first difference function and the second difference function are less than or equal to a preset threshold, then the transformer winding is not faulty.

[0091] In one implementation scenario, a determination is made as to whether the fluctuation amplitudes of the first difference function and the second difference function exceed a first amplitude threshold. If so, a transformer winding fault is determined to be present. Specifically, a pre-set first amplitude threshold can reflect the transformer's tolerance for the fluctuation amplitude. Once the fluctuation amplitude exceeds the first amplitude threshold, a transformer winding fault is determined to be present. This amplitude threshold can be obtained through calculation or by repeated actual operational testing.

[0092] In another implementation scenario, a determination is made as to whether the fluctuation frequency of the first difference function and the second difference function exceeds a first frequency threshold. If so, a transformer winding fault is determined to have occurred. Specifically, a pre-set first frequency threshold can reflect the transformer's tolerance for the fluctuation frequency. Once the fluctuation frequency exceeds the first frequency threshold, a transformer winding fault is determined to have occurred. This frequency threshold can be obtained through calculation or by repeated actual operational testing.

[0093] In another implementation scenario, it is determined whether the fluctuations of the first difference function and the second difference function satisfy a predetermined pattern. If they do not, a transformer winding fault is determined. Specifically, a normal fluctuation pattern is obtained in advance through calculation or repeated testing. If the fluctuations deviate from this pattern, a transformer winding fault can be determined.

[0094] The preset fluctuation pattern can refer to changes in a function curve. Some function curve changes may not be simply summarized by changes in frequency or amplitude. Therefore, a preset fluctuation pattern can be set for judgment. For example, the curve changes of the first difference function and the second difference function during previous faults can be set as a preset pattern. When a change similar to the preset pattern occurs, it is determined to be a transformer winding fault.

[0095] By using the fluctuation amplitude, frequency, regularity and other characteristics of the first difference function and the second difference function, it is possible to sensitively and accurately evaluate and analyze whether a transformer fault occurs.

[0096] From the above description, it can be seen that the present invention applies current excitation to the transformer winding, determines the self-inductance of the transformer winding based on the current excitation and the self-inductance coefficient of the transformer winding, and determines the mutual inductance of the transformer winding based on the current excitation and the mutual inductance coefficient of the transformer winding. The equivalent inductance under ideal conditions is calculated based on the self-inductance and mutual inductance, and the series capacitance and grounding capacitance of the transformer winding are obtained, and the equivalent capacitance under ideal conditions is calculated based on the series capacitance and grounding capacitance. Furthermore, the first-order grounding coefficient of the driving point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is grounded, and the first-order open-circuit coefficient of the driving point admittance is determined based on the peak frequency and valley frequency when the neutral point of the transformer winding is open, and the first-order grounding coefficient is converted to the peak frequency and valley frequency when the neutral point of the transformer winding is open. As the approximate inductance actually measured, the first-order open-circuit coefficient As the actual measured approximate capacitance. Finally, a first difference function is determined based on the equivalent inductance, a preset scaling factor, and the first-order grounding coefficient, and a second difference function is determined based on the equivalent capacitance and the first-order open-circuit coefficient. The first difference function can be used to represent the variation characteristics between the ideal equivalent inductance and the actual measured approximate inductance, while the second difference function can be used to represent the variation characteristics between the ideal equivalent capacitance and the actual measured approximate capacitance. Therefore, transformer winding fault detection is performed based on the comparison of the fluctuations of the first and second difference functions with a preset threshold. The present invention detects current changes and combines them with the frequency response (frequency response is more sensitive than current response) to avoid minor or minimal current changes due to less severe winding deformation. The first-order grounding coefficient and the first-order open-circuit coefficient of the driving point admittance (approximately equivalent inductance and equivalent capacitance, respectively) are analyzed using a difference function with the ideal equivalent inductance and capacitance measured in the non-operating state to determine the presence of early faults, promptly detect winding faults, reduce downtime and repair costs, extend equipment life, and improve the overall operational efficiency of the power grid.

[0097] like Figure 3 As shown, Figure 3 A method for detecting a transformer winding fault based on frequency response is provided in accordance with another embodiment of the present invention. The method comprises: S301: Determine the fault level of the transformer winding according to a comparison between the fluctuation of the first difference function and / or the second difference function and a preset fault level judgment condition.

[0098] S3011: Determine that the fluctuation amplitude of the first difference function and / or the second difference function reaches a second amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a second frequency threshold, the fault level of the transformer winding is a level one fault.

[0099] S3012: Determine that the fluctuation amplitude of the first difference function and / or the second difference function reaches a third amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a third frequency threshold, the fault level of the transformer winding is a secondary fault.

[0100] In one implementation scenario, in order to implement fault classification judgment, the fault level judgment condition can set multiple classification thresholds for the amplitude, frequency and other characteristics of the fluctuation of the first difference function and the second difference function. Specifically, when the amplitude of the fluctuation of the first difference function and / or the second difference function reaches the second amplitude threshold, or when the frequency of the fluctuation of the first difference function and / or the second difference function reaches the second frequency threshold, it can be identified as a first-level fault; when the amplitude of the fluctuation of the first difference function and / or the second difference function reaches the third amplitude threshold, or when the frequency of the fluctuation of the first difference function and / or the second difference function reaches the third frequency threshold, it can be identified as a second-level fault. Among them, the specific threshold value can be determined according to the actual situation of the power grid or transformer, and no specific limitation is made here.

[0101] like Figure 4 As shown, Figure 4 A schematic diagram of a transformer winding fault detection system based on frequency response according to an embodiment of the present invention is provided. A transformer winding fault detection system 10 based on frequency response includes: The equivalent inductance and equivalent capacitance determination module 11 is used to determine the equivalent inductance and equivalent capacitance of the transformer winding.

[0102] The first-order grounding coefficient determining module 12 of the driving point admittance is used to determine the first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded.

[0103] The first-order open-circuit coefficient determination module 13 of the driving-point admittance is used to determine the first-order open-circuit coefficient of the driving-point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open-circuited.

[0104] The first difference function and second difference function determining module 14 is configured to determine the first difference function according to the equivalent inductance and the first-order grounding coefficient, and to determine the second difference function according to the equivalent capacitance and the first-order open-circuit coefficient.

[0105] The fault detection module 15 is configured to perform transformer winding fault detection based on a comparison between the fluctuations of the first difference function and the second difference function and a preset threshold.

[0106] In one implementation scenario, in the equivalent inductance and equivalent capacitance determination module 11, current excitation is applied to the transformer winding, and the current excitation is determined after being geometrically scaled according to the normal operating current of the transformer winding at a preset scaling rate; the self-inductance of the transformer winding is determined according to the current excitation and the self-inductance coefficient of the transformer winding, and the mutual inductance of the transformer winding is determined according to the current excitation and the mutual inductance coefficient of the transformer winding; the equivalent inductance is determined based on the self-inductance and the mutual inductance; the series capacitance and ground capacitance of the transformer winding are obtained, and the equivalent capacitance is determined based on the series capacitance and the ground capacitance.

[0107] In the first-order grounding coefficient determination module 12 of the driving point admittance, the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded are collected; Determine the first-order grounding coefficient of the driving point admittance, where is the first-order grounding coefficient of the driving point admittance, is the peak frequency when the neutral point is grounded, is the valley frequency when the neutral point is grounded; In the first-order open-circuit coefficient determination module 13 of the driving point admittance, the peak frequency and valley frequency when the neutral point of the transformer winding is open are collected; Determine the first-order open-loop coefficient of the driving-point admittance, where is the first-order open-circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, It is the valley frequency when the neutral point is open.

[0108] In the first difference function and the second difference function determination module 14, according to Determine a first difference function, where is the first difference function, is the equivalent inductance, For the preset zoom ratio, is the first-order grounding coefficient of the driving point admittance; according to Determine a second difference function, where is the second difference function, is the equivalent capacitance, The first difference function is used to represent the variation characteristics of the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function is used to represent the variation characteristics of the ideal equivalent capacitance and the actual measured approximate capacitance.

[0109] In the fault detection module 15, it is determined whether the fluctuation amplitude or fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold value, wherein the preset threshold value is a first amplitude threshold value or a first frequency threshold value; if the fluctuation amplitude or fluctuation frequency of the first difference function and the second difference function is greater than the preset threshold value, the transformer winding has a fault; if the fluctuation amplitude of the first difference function and the second difference function is less than or equal to the preset threshold value, the transformer winding has not a fault. Therefore, the fault detection module 17 can determine whether there is a fault in the winding by calculating the change characteristics of the ideal equivalent inductance and ideal equivalent capacitance and the actual measured approximate inductance and actual measured approximate capacitance.

[0110] like Figure 5 As shown, Figure 5The structure diagram of an embodiment of the medium provided by the present invention. The medium 20 stores at least one computer program 21, which is executed by the processor to implement the following Figure 1 、 Figure 2 and Figure 3 In one embodiment, the medium 20 may be a memory chip, a hard disk, a mobile hard disk, a USB flash drive, an optical disk, or other readable and writable storage tools, or a server.

[0111] Additionally, the processes depicted in the accompanying figures do not necessarily have to be performed in the particular order shown, or sequential order, to achieve desired results. In certain implementations, multitasking and parallel processing are also possible or may be advantageous.

[0112] The various embodiments in this specification are described in a progressive manner. Similar portions between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the device, apparatus, and non-volatile computer-readable storage medium embodiments are described briefly because they are generally similar to the method embodiments. For relevant portions, refer to the description of the method embodiments.

[0113] The apparatus, device, non-volatile computer-readable storage medium and method provided in the embodiments of this specification correspond to each other. Therefore, the apparatus, device, and non-volatile computer storage medium also have similar beneficial technical effects as the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the corresponding apparatus, device, and non-volatile computer storage medium will not be repeated here.

[0114] The systems, devices, modules, or units described in the above embodiments may be implemented by computer chips or entities, or by products having certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0115] For ease of description, the above devices are described in terms of their functions and are divided into various units and described separately. Of course, when implementing this specification, the functions of each unit can be implemented in the same or multiple software and / or hardware. Those skilled in the art will appreciate that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the embodiments of this specification can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0116] This specification is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems) and computer program products according to the embodiments of this specification. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0117] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0118] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0119] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0120] Memory may include non-permanent storage in a computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0121] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0122] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0123] This specification may be described in the general context of computer-executable instructions, such as program modules, executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. This specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media, including storage devices.

[0124] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are described briefly because they are generally similar to the method embodiments. For relevant parts, refer to the description of the method embodiments.

[0125] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A transformer winding fault detection method based on frequency response, characterized in that: The method comprises: determining an equivalent inductance and an equivalent capacitance of the transformer winding; determining a first-order grounding coefficient of the driving point admittance according to a peak frequency and a valley frequency when the neutral point of the transformer winding is grounded; Determining a first-order open-circuit coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open-circuited; Determining a first difference function according to the equivalent inductance and the first-order grounding coefficient, and determining a second difference function according to the equivalent capacitance and the first-order open-circuit coefficient; Fault detection of the transformer winding is performed based on a comparison between fluctuations of the first difference function and the second difference function and a preset threshold.

2. The method for detecting transformer winding faults based on frequency response according to claim 1, characterized in that: Determining the first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded specifically includes: collecting the peak frequency and valley frequency when the neutral point of the transformer winding is grounded; according to Determine the first-order grounding coefficient of the driving point admittance, where is the first-order grounding coefficient of the driving point admittance, is the peak frequency when the neutral point is grounded, It is the valley frequency when the neutral point is grounded.

3. The method for detecting transformer winding faults based on frequency response according to claim 1, characterized in that: Determining the first-order open-circuit coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open specifically includes: collecting the peak frequency and valley frequency when the neutral point of the transformer winding is open; according to Determine the first-order open-loop coefficient of the driving-point admittance, where is the first-order open-circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, It is the valley frequency when the neutral point is open.

4. A transformer winding fault detection method based on frequency response according to claim 2 or 3, characterized in that: The determining of a first difference function according to the equivalent inductance and the first-order grounding coefficient, and determining a second difference function according to the equivalent capacitance and the first-order open-circuit coefficient, specifically includes: according to Determine a first difference function, where is the first difference function, is the equivalent inductance, For the preset zoom ratio, is the first-order grounding coefficient of the driving point admittance; according to Determine a second difference function, where is the second difference function, is the equivalent capacitance, is the first-order open-circuit coefficient of the driving-point admittance.

5. The method for detecting transformer winding faults based on frequency response according to claim 4, characterized in that: The performing of the transformer winding fault detection according to the comparison between the fluctuation of the first difference function and the second difference function and a preset threshold value specifically includes: Determining whether the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, where the preset threshold is a first amplitude threshold or a first frequency threshold; If the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold, the transformer winding fails; If the fluctuation amplitude of the first difference function and the second difference function is less than or equal to a preset threshold, the transformer winding does not occur.

6. The method for detecting transformer winding faults based on frequency response according to claim 1, characterized in that: The method further specifically includes: Determining that the fault level of the transformer winding is a primary fault when the fluctuation amplitude of the first difference function and / or the second difference function reaches a second amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a second frequency threshold; It is determined that the fluctuation amplitude of the first difference function and / or the second difference function reaches a third amplitude threshold, or when the fluctuation frequency of the first difference function and / or the second difference function reaches a third frequency threshold, the fault level of the transformer winding is a secondary fault.

7. A transformer winding fault detection system based on frequency response, characterized in that: The system comprises: An equivalent inductance and equivalent capacitance acquisition module, used to determine the equivalent inductance and equivalent capacitance of the transformer winding; a first-order grounding coefficient determination module for driving point admittance, configured to determine the first-order grounding coefficient of the driving point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is grounded; a first-order open-circuit coefficient determination module for driving-point admittance, configured to determine the first-order open-circuit coefficient of the driving-point admittance according to the peak frequency and the valley frequency when the neutral point of the transformer winding is open; a first difference function and a second difference function determining module, configured to determine a first difference function according to the equivalent inductance and the first-order grounding coefficient, and to determine a second difference function according to the equivalent capacitance and the first-order open-circuit coefficient; A fault detection module is used to perform fault detection on the transformer winding based on a comparison between the fluctuations of the first difference function and the second difference function and a preset threshold.

8. A computer-readable storage medium, characterized in that A computer program is stored, and when the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 6.

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