Transformer winding fault detection method, system, device and medium based on current change

Abstract

The embodiment of the present application relates to the technical field of transformer fault detection, and discloses a transformer winding fault detection method, system, device and medium based on current change, which comprises the following steps: applying a current excitation to the transformer winding, wherein the current excitation is determined according to the normal working current of the transformer winding after equal ratio scaling at a preset scaling rate; 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; determining the equivalent inductance according to the self-inductance and the mutual inductance; obtaining the series capacitance and the grounding capacitance of the transformer winding, determining the equivalent capacitance according to the series capacitance and the grounding capacitance; determining a first difference function according to the equivalent inductance and the preset scaling rate, and determining a second difference function according to the equivalent capacitance; and performing the fault detection of the transformer winding according to the comparison between the fluctuations of the first difference function and the second difference function and the preset threshold, so as to realize early and sensitive detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer fault detection, and in particular to a transformer winding fault detection method, system, device and medium based on current change. BACKGROUND

[0002] When the transformer is running for a long time or bearing load, the winding will be affected by a large current and temperature. Long-term high temperature and current change will cause the winding insulation material to gradually age, thereby reducing its insulation performance and forming local weaknesses. When the transformer suddenly overloads or the current suddenly changes, these weaknesses may cause the winding to short circuit or break. In addition, due to external mechanical impact, vibration or improper operation, etc., physical damage may also be caused to the winding, thereby causing fault failure. The winding, as the core component of the transformer, is related to the stable operation of the transformer.

[0003] For transformer winding fault detection, there are many technical solutions on the market at present. For example, CN119510954A proposes a fault detection method based on a running state matrix, which analyzes the deviation vector matrix between the preset standard running matrix and the actual running matrix to determine whether the current running state is abnormal. CN119046854B obtains data sequences of each position area of the distribution transformer, and uses the RRCF model to detect abnormal points in the data to achieve the effect of fault diagnosis.

[0004] However, the existing detection method has poor accuracy for early fault judgment, and cannot more sensitively respond to transformer winding faults, nor can it diagnose the severity of the fault. SUMMARY

[0005] Therefore, it is necessary to propose a transformer winding fault detection method, system, device and medium based on current change to solve the above problems.

[0006] A transformer winding fault detection method based on current change, the method comprising:

[0007] Applying a current excitation to the transformer winding, the current excitation being determined by equi-scaling the normal working current of the transformer winding at a preset scaling rate.

[0008] 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.

[0009] Determining the equivalent inductance according to the self-inductance and the mutual inductance.

[0010] acquire series capacitance and ground capacitance of the transformer winding, determine equivalent capacitance according to the series capacitance and the ground capacitance.

[0011] determine a first difference function according to the equivalent inductance and the preset scaling rate, and determine a second difference function according to the equivalent capacitance.

[0012] perform fault detection of the transformer winding according to comparison between fluctuations of the first difference function and the second difference function and a preset threshold.

[0013] wherein, the self-inductance of the transformer winding is determined according to the current excitation and a self-inductance coefficient of the transformer winding, and the mutual inductance of the transformer winding is determined according to the current excitation and a mutual inductance coefficient of the transformer winding, and specifically includes:

[0014] determine the self-inductance of the transformer winding, wherein, is the self-inductance of the transformer winding, is the self-inductance coefficient of the transformer winding, is the current excitation. determine the mutual inductance of the transformer winding, wherein, is the mutual inductance between the transformer winding and the transformer winding, is the mutual inductance coefficient between the transformer winding and the transformer winding,

[0015] is the current excitation.

[0016] determine the equivalent inductance according to the self-inductance and the mutual inductance, and specifically includes: determine the equivalent inductance according to the self-inductance and the mutual inductance, and specifically includes: is the equivalent inductance, is the mutual inductance between the transformer winding and the transformer winding, is the self-inductance of the transformer winding. wherein, the equivalent inductance is determined according to the self-inductance and the mutual inductance, and specifically includes: determine the equivalent inductance according to the self-inductance and the mutual inductance, and specifically includes:

[0017] determine the equivalent inductance according to the self-inductance and the mutual inductance, and specifically includes:

[0018] determine the equivalent inductance according to the self-inductance and the mutual inductance, and specifically includes: is the equivalent inductance, is the mutual inductance between the transformer winding and the transformer winding, is the self-inductance of the transformer winding. wherein, the series capacitance and the ground capacitance of the transformer winding are acquired, and the equivalent capacitance is determined according to the series capacitance and the ground capacitance, and specifically includes:

[0019]

[0020] ​​​​Obtaining series capacitance and ground capacitance of the transformer winding.

[0021] According to determining equivalent capacitance, wherein, the equivalent capacitance, the series capacitance, the ground capacitance.

[0022] According to the equivalent inductance and the preset scaling rate to determine the first difference function, and according to the equivalent capacitance to determine the second difference function, specifically comprising:

[0023] Obtaining the first-order ground coefficient and the first-order open circuit coefficient of the transformer winding.

[0024] According to the equivalent inductance, the preset scaling rate and the first-order ground coefficient to determine the first difference function, and according to the equivalent capacitance and the first-order open circuit coefficient to determine the second difference function.

[0025] According to the equivalent inductance, the preset scaling rate and the first-order ground coefficient to determine the first difference function, and according to the equivalent capacitance and the first-order open circuit coefficient to determine the second difference function, specifically comprising:

[0026] According to determining the first difference function, wherein, the first difference function, the equivalent inductance, the preset scaling rate, the first-order ground coefficient of the driving point admittance.

[0027] According to determining the second difference function, wherein, the second difference function, the equivalent capacitance, the first-order open circuit coefficient of the driving point admittance.

[0028] According to the comparison between the fluctuation of the first difference function and the second difference function and the preset threshold value to perform the fault detection of the transformer winding, specifically comprising:

[0029] Determining whether the fluctuation amplitude or the fluctuation frequency of the first difference function and the second difference function is greater than the preset threshold value, and the preset threshold value is a first amplitude threshold value or a first frequency threshold value.

[0030] If the fluctuation amplitude or the 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.

[0031] If the fluctuation amplitudes of the first difference function and the second difference function are less than or equal to a preset threshold, it is determined that the transformer winding has not occurred.

[0032] The method further comprises:

[0033] The fault level of the transformer winding is determined 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.

[0034] A transformer winding fault detection system based on current change, the system comprising:

[0035] A current excitation determination module for applying a current excitation to the transformer winding, the current excitation being determined by equi-proportionally scaling the normal working current of the transformer winding by a preset scaling rate.

[0036] A self-inductance and mutual-inductance determination module for 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.

[0037] An equivalent inductance determination module for determining an equivalent inductance according to the self-inductance and the mutual-inductance.

[0038] An equivalent capacitance determination module for obtaining a series capacitance and a ground capacitance of the transformer winding, and determining an equivalent capacitance according to the series capacitance and the ground capacitance.

[0039] A first difference function and a second difference function determination module for determining a first difference function according to the equivalent inductance and the preset scaling rate, and determining a second difference function according to the equivalent capacitance.

[0040] A fault detection module for performing fault detection of the transformer winding according to a comparison between the fluctuation of the first difference function and the second difference function and a preset threshold.

[0041] A computer readable storage medium storing a computer program, the computer program being executed by a processor to cause the processor to perform the steps of the method.

[0042] A computer device comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to cause the processor to perform the steps of the method.

[0043] The embodiments of the present application have the following beneficial effects:

[0044] The application applies current excitation to a transformer winding, determines self-induction of the transformer winding according to the current excitation and a self-induction coefficient of the transformer winding, and determines mutual induction of the transformer winding according to the current excitation and a mutual induction coefficient of the transformer winding. The equivalent inductance in an ideal state is calculated according to the self-induction and the mutual induction, and the series capacitance and the ground capacitance of the transformer winding are obtained, and the equivalent capacitance in an ideal state is calculated according to the series capacitance and the ground capacitance. Further, the first difference function is determined according to the equivalent inductance and a preset scaling rate, and the second difference function is determined according to the equivalent capacitance, the first difference function can be used to represent the change characteristics of the ideal equivalent inductance and the approximate inductance actually measured, and the second difference function can be used to represent the change characteristics of the ideal equivalent capacitance and the approximate capacitance actually measured. Therefore, the application detects the current change, obtains the fluctuation of the difference function caused by the slight fault, and judges the early fault of the transformer winding according to the comparison between the fluctuation of the first difference function and the second difference function and the preset threshold, so that the winding fault can be found in time, the downtime and the maintenance cost are reduced, the service life of the equipment is improved, and the overall operation efficiency of the power grid is improved. BRIEF DESCRIPTION OF DRAWINGS

[0045] 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 needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0046] In which:

[0047] Figure 1 A flowchart of an embodiment of a transformer winding fault detection method based on current change provided by the present application;

[0048] Figure 2 A flowchart of another embodiment of a transformer winding fault detection method based on current change provided by the present application;

[0049] Figure 3 A structural diagram of an embodiment of a transformer winding fault detection system based on current change provided by the present application;

[0050] Figure 4 A structural diagram of an embodiment of the equipment provided by the present application;

[0051] Figure 5 A structural diagram of an embodiment of the medium provided by the present application. DETAILED DESCRIPTION

[0052] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0053] As Figure 1 shown, Figure 1 is a flowchart of an embodiment of a transformer winding fault detection method based on current change provided by the present application. The transformer winding fault detection method based on current change comprises the following steps.

[0054] S101: Apply current excitation to the transformer winding, which is determined by equal ratio scaling of the normal working current of the transformer winding at a preset scaling rate.

[0055] In one implementation scenario, in order to detect the transformer, current excitation needs to be applied to the winding of the transformer, so as to subsequently calculate the self-inductance and mutual inductance of the transformer winding under the condition of the current excitation. The self-inductance and mutual inductance of the transformer winding can be calculated simultaneously under the condition of applying current excitation only once, or the same current excitation can be applied twice to calculate the self-inductance and mutual inductance of the transformer winding respectively.

[0056] Specifically, since the voltage and current are too large during actual work, it is difficult to control, so the current can be scaled appropriately during data collection and detection, so as to prevent the distortion of measurement data caused by too large current. For example, the current excitation can be scaled at a scaling rate of 1 / 1000. Since the current excitation is scaled here, the scaling rate needs to be substituted into the operation in the subsequent calculation process, so as to prevent inaccurate data.

[0057] S102: 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.

[0058] In one implementation scenario, when the self-inductance is determined, the current excitation determined by equal ratio scaling of the normal working current of the transformer winding at a preset scaling rate (assuming that the preset scaling rate is 1 / 1000), the self-inductance is calculated according to the following formula:

[0059] ;

[0060] wherein,​​ L1 is the self-inductance of the first winding of the transformer, K1 is the self-inductance coefficient of the first winding, L2 is the self-inductance of the second winding of the transformer, K2 is the self-inductance coefficient of the second winding, , N is the total number of windings, I is the current excitation determined by the normal working current of the transformer windings scaled by a preset scaling ratio, dI / dt is the rate of change of the current. The self-inductance coefficient K can be calculated by the magnetic permeability N, the number of turns of the coil, A, the cross-sectional area of the coil, L, the length of the coil.

[0061] ;

[0062] wherein, is the magnetic permeability, N is the number of turns of the coil, A is the cross-sectional area of the coil, L is the length of the coil.

[0063] In determining the mutual inductance , under the same current excitation conditions given to different windings as in determining the self-inductance, the mutual inductance is calculated according to the following formula:

[0064] ;

[0065] wherein, M12 is the mutual inductance between the first winding and the second winding of the transformer, I is the current excitation, K12 is the mutual inductance coefficient of the first winding and the second winding, K21 is the mutual inductance coefficient of the first winding and the second winding, can be determined according to the self-inductance coefficients of different transformer windings and the degree of magnetic coupling between the windings, as shown in the following formula: ; wherein, k is the coupling coefficient, taking a value of 1, L1 is the self-inductance of the first winding of the transformer, L2 is the self-inductance of the second winding of the transformer.

[0066] ;

[0067] wherein, k is the coupling coefficient, taking a value of 1, L1 is the self-inductance of the first winding of the transformer, L2 is the self-inductance of the second winding of the transformer.

[0068] ​​​​​It should be noted that self-induction refers to the electromotive force generated on the transformer winding due to the change of current, that is, when the current through a winding changes, the winding itself will induce an opposite electromotive force due to the change of the magnetic field, which is called self-induction. Mutual induction refers to the mutual induction between two adjacent windings, that is, when the current in one winding changes, it will generate a changing magnetic field, which in turn induces an electromotive force in the adjacent winding, which is called mutual induction. The equivalent inductance in the ideal state can be calculated according to the self-induction and mutual induction, and the equivalent capacitance in the ideal state can be calculated according to the series capacitance and the ground capacitance.

[0069] S103: Determine the equivalent inductance according to the self-induction and mutual induction.

[0070] In one implementation scenario, only the mutual inductance coefficient between the adjacent two windings is considered when calculating the equivalent inductance. The equivalent inductance in the ideal state can be calculated by the following formula:

[0071] ;

[0072] wherein, L is the equivalent inductance, M is the mutual inductance between the i-th winding and the j-th winding, L is the self-inductance of the i-th winding of the transformer.

[0073] In addition, since the main purpose of the present embodiment is to detect early faults of the transformer, the goal is to be qualitative rather than quantitative, and the failure of any one winding will cause the inductance data characteristics to change significantly, therefore, in another optional implementation, in order to simplify the difficulty of data analysis, only the one-way mutual inductance effect is considered when calculating the equivalent inductance, 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:

[0074] ;

[0075] wherein, L is the equivalent inductance, M is the mutual inductance between the i-th winding and the j-th winding, L is the self-inductance of the i-th winding of the transformer.

[0076] It should be noted that in actual application, it can be determined according to actual needs which calculation method of equivalent inductance to select.

[0077] ​​S104: Obtain the series capacitance and ground capacitance of the transformer winding, and determine the equivalent capacitance according to the series capacitance and ground capacitance.

[0078] 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:

[0079] ;

[0080] 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.

[0081] 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.

[0082] Calculating ground capacitance When the winding is approximated as a coaxial cylindrical model, the grounding capacitance It can be calculated by the following formula:

[0083] ;

[0084] 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.

[0085] Furthermore, the equivalent capacitance under ideal conditions is calculated according to the following formula:

[0086] ;

[0087] in, is the equivalent capacitance, is the series capacitor, is the grounding capacitor.

[0088] S105: determining a first difference function according to the equivalent inductance and a preset scaling rate, and determining a second difference function according to the equivalent capacitance.

[0089] In one implementation scenario, the driving point admittance of the transformer refers to the equivalent admittance viewed from one side of the transformer, reflecting the response characteristics of the side port to the current. The driving point admittance characterizes the coefficient relationship between the input and output of the transformer winding, and the first-order ground coefficient may be approximately equal to the equivalent inductance The first-order open circuit coefficient may be approximately equal to the equivalent capacitance . Therefore, the first-order ground coefficient may be taken as the approximate inductance actually measured, and the first-order open circuit coefficient may be taken as the approximate capacitance actually measured. By combining the current change into the calculation, the sensitivity of fault detection can be improved.

[0090] In determining the first-order ground coefficient and the first-order open circuit coefficient of the driving point admittance, first, 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 by a frequency meter or an impedance meter. The neutral point of the transformer refers to a point connected at the end of the winding, which is usually used for grounding or connecting protection devices. The selection of the neutral point is closely related to the connection mode of the winding.

[0091] Further, the first-order ground coefficient of the driving point admittance is determined according to the formula as shown below:

[0092] ;

[0093] wherein, is the first-order ground 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.

[0094] The first-order open circuit coefficient of the driving point admittance is determined according to the formula as shown below:

[0095] ;

[0096] wherein, is the first-order open circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, is the valley frequency when the neutral point is open.

[0097] Further, the first difference function is used to represent the variation characteristics of the ideal equivalent inductance and the approximate inductance actually measured, and the second difference function is used to represent the variation characteristics of the ideal equivalent capacitance and the approximate capacitance actually measured. The first difference function is determined according to the formula as shown below:

[0098] ;

[0099] wherein, is a first difference function, is an equivalent inductance, is a preset scaling rate, is a first order ground coefficient of the driving point admittance.

[0100] A second difference function is determined according to the following formula:

[0101] ;

[0102] wherein, is a second difference function, is an equivalent capacitance, is a first order open circuit coefficient of the driving point admittance.

[0103] S106: performing fault detection of the transformer winding according to comparison between fluctuation of the first difference function and the second difference function and a preset threshold.

[0104] In one implementation scenario, the fault detection of the transformer winding is performed according to comparison between fluctuation of the first difference function and the second difference function and a preset threshold. The first difference function is used to represent variation characteristics of the ideal equivalent inductance and the actually measured approximate inductance, and the second difference function is used to represent variation characteristics of the ideal equivalent capacitance and the actually measured approximate capacitance. When the winding has a fault such as axial deformation or turn-to-turn short circuit, the equivalent inductance will be obviously changed. When the winding has a fault such as radial deformation, the equivalent capacitance will be obviously changed. Therefore, the variation characteristics of the ideal equivalent inductance and the ideal equivalent capacitance and the actually measured approximate inductance and the actually measured approximate capacitance can be calculated to determine whether the winding has a fault.

[0105] Specifically, the values of the first difference function and the second difference function should be in a stable state under normal operation of the transformer, and when the first difference function and the second difference function have obvious fluctuation, it can be considered that the winding of the transformer has a fault.

[0106] As can be seen from the above description, 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. Based on the self-inductance and mutual inductance, the equivalent inductance under ideal conditions is calculated, and the series capacitance and ground capacitance of the transformer winding are obtained. The equivalent capacitance under ideal conditions is calculated based on the series capacitance and ground capacitance. Further, a first difference function is determined based on the equivalent inductance and a preset scaling factor, and a second difference function is determined based on the equivalent capacitance. The first difference function can be used to represent the change characteristics of the ideal equivalent inductance and the actual measured approximate inductance, and the second difference function can be used to represent the change characteristics of the ideal equivalent capacitance and the actual measured approximate capacitance. Therefore, the present invention obtains the difference function fluctuation caused by minor faults by detecting current changes, and judges the early fault of the transformer winding based on the comparison of the fluctuation of the first difference function and the second difference function with the preset threshold value, thereby timely detecting winding faults, reducing downtime and maintenance costs, extending the service life of equipment, and improving the overall operating efficiency of the power grid.

[0107] like Figure 2 As shown, Figure 2 A flow chart of another embodiment of a transformer winding fault detection method based on current variation provided by the present invention. A transformer winding fault detection method based on current variation, the method comprising:

[0108] 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.

[0109] It should be noted that step S201 Figure 1 This has been discussed in detail in the implementation scenario shown and will not be repeated here.

[0110] 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.

[0111] In one implementation scenario, the self-inductance of the transformer winding is determined according to the following formula:

[0112] ;

[0113] in, For transformer The self-inductance of a winding, For the The self-inductance of the winding, is current excitation;

[0114] Further, the mutual inductance of the transformer windings is determined according to the self-inductance of the different transformer windings and the degree of magnetic coupling between the windings.

[0115] The mutual inductance of the transformer windings is determined according to the following formula:

[0116] ;

[0117] wherein, is the mutual inductance between the i-th winding and the j-th winding of the transformer, is the mutual inductance of the i-th winding and the j-th winding, is the mutual inductance of the i-th winding and the j-th winding, is the current excitation. S203: Determine the equivalent inductance according to the self-inductance and the mutual inductance. In one implementation scenario, the equivalent inductance is determined according to the following formula:

[0118]

[0119] ;

[0120] ;

[0121] wherein, is the equivalent inductance, is the mutual inductance between the i-th winding and the j-th winding of the transformer, is the self-inductance of the i-th winding of the transformer. S204: Obtain the series capacitance and the ground capacitance of the transformer windings, and determine the equivalent capacitance according to the series capacitance and the ground capacitance.

[0122] In one implementation scenario, the series capacitance and the ground capacitance of the transformer windings are obtained.

[0123] Further, the equivalent capacitance is determined according to the following formula:

[0124]

[0125] ; wherein,

[0126] is the equivalent capacitance, is the series capacitance, is the ground capacitance. S205: Obtain the first-order ground coefficient and the first-order open circuit coefficient of the transformer windings.

[0127]

[0128] ​​​In one implementation scenario, a first-order ground 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, and a 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.

[0129] Specifically, 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.

[0130] Further, the first-order ground 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, and 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.

[0131] Specifically, the first-order ground coefficient of the driving point admittance is determined according to the formula as shown below:

[0132] ;

[0133] wherein, is the first-order ground 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.

[0134] The first-order open circuit coefficient of the driving point admittance is determined according to the formula as shown below:

[0135] ;

[0136] wherein, is the first-order open circuit coefficient of the driving point admittance, is the peak frequency when the neutral point is open, is the valley frequency when the neutral point is open.

[0137] S206: determining a first difference function according to the equivalent inductance, the preset scaling rate and the first-order ground coefficient, and determining a second difference function according to the equivalent capacitance and the first-order open circuit coefficient.

[0138] In one implementation scenario, the first difference function is determined according to the formula as shown below:

[0139] ;

[0140] wherein, is the first difference function, is the equivalent inductance, is the preset scaling rate, is the first-order ground coefficient of the driving point admittance.

[0141] The second difference function is determined according to the following formula:

[0142] ;

[0143] wherein, is the second difference function, is the equivalent capacitance, is the first open circuit coefficient of the driving point admittance.

[0144] S207: Determine whether the fluctuation amplitude or fluctuation frequency of the first difference function and the second difference function is greater than a preset threshold value, which is a first amplitude threshold value or a first frequency threshold value.

[0145] S2071: 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.

[0146] S2072: 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 no fault.

[0147] In one implementation scenario, it is determined whether the fluctuation amplitude of the first difference function and the second difference function exceeds the first amplitude threshold value, respectively. If it exceeds the first amplitude threshold value, it is determined that the transformer winding has a fault. Specifically, the first amplitude threshold value is set in advance, which can reflect the tolerance of the transformer to the fluctuation amplitude. Once the fluctuation amplitude exceeds the first amplitude threshold value, it is determined that the transformer winding has a fault. The amplitude threshold value can be obtained by calculation, or can be obtained by summarizing multiple repeated actual operation tests.

[0148] In another implementation scenario, it is determined whether the fluctuation frequency of the first difference function and the second difference function exceeds the first frequency threshold value, respectively. If it exceeds the first frequency threshold value, it is determined that the transformer winding has a fault. Specifically, the first frequency threshold value is set in advance, which can reflect the tolerance of the transformer to the fluctuation frequency. Once the fluctuation frequency exceeds the first frequency threshold value, it is determined that the transformer winding has a fault. The frequency threshold value can be obtained by calculation, or can be obtained by summarizing multiple repeated actual operation tests.

[0149] In yet another implementation scenario, it is determined whether the fluctuation of the first difference function and the second difference function satisfies a preset rule, respectively. If it does not satisfy the preset rule, it is determined that the transformer winding has a fault. Specifically, the normal fluctuation change rule is obtained in advance by calculation or repeated tests. When the fluctuation deviates from the change rule, it is determined that the transformer winding has a fault.

[0150] The fluctuation preset rule can refer to a function curve change. Some function curve changes can not be summarized by a change in frequency or amplitude alone, and thus a fluctuation preset rule can be preset for determination. For example, the curve change of the first difference function and the second difference function when a fault occurs in the past can be set as a preset rule, and when a change in the preset rule occurs, it is determined that the transformer winding has a fault.

[0151] Through the fluctuation amplitude, frequency, and rule of the first difference function and the second difference function, the transformer fault can be sensitively and accurately evaluated and analyzed.

[0152] S208: Determine the fault level of the transformer winding according to the comparison of the fluctuation of the first difference function and / or the second difference function with the preset fault level determination condition.

[0153] In one implementation scenario, 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, the fault level of the transformer winding is a first-level fault.

[0154] When 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 second-level fault.

[0155] Specifically, to implement fault grading determination, the fault level determination condition can set multiple grading 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 a second amplitude threshold, or when the frequency of the fluctuation of the first difference function and / or the second difference function reaches a second frequency threshold, it can be determined as a first-level fault; when the amplitude of the fluctuation of the first difference function and / or the second difference function reaches a third amplitude threshold, or when the frequency of the fluctuation of the first difference function and / or the second difference function reaches a third frequency threshold, it can be determined as a second-level fault. The specific threshold values can be determined according to the actual situation of the power grid or the transformer, and are not specifically limited here.

[0156] As can be known from the above description, the application applies current excitation to the transformer winding, determines the self-induction of the transformer winding according to the current excitation and the self-induction coefficient of the transformer winding, and determines the mutual induction of the transformer winding according to the current excitation and the mutual induction coefficient of the transformer winding. The equivalent inductance in the ideal state is calculated according to the self-induction and the mutual induction, and the series capacitance and the ground capacitance of the transformer winding are obtained, and the equivalent capacitance in the ideal state is calculated according to the series capacitance and the ground capacitance. Further, the first-order ground coefficient of the driving point admittance is determined according to the peak frequency and the trough 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 according to the peak frequency and the trough frequency when the neutral point of the transformer winding is open, the first-order ground coefficient is taken as the approximate inductance actually measured, and the first-order open circuit coefficient is taken as the approximate capacitance actually measured. Finally, the first difference function is determined according to the equivalent inductance, the preset scaling rate and the first-order ground coefficient, and the second difference function is determined according to the equivalent capacitance and the first-order open circuit coefficient, the first difference function can be used to represent the change characteristics of the ideal equivalent inductance and the approximate inductance actually measured, and the second difference function can be used to represent the change characteristics of the ideal equivalent capacitance and the approximate capacitance actually measured.

[0157] Therefore, the application determines the equivalent inductance and the equivalent capacitance based on the current change, determines the approximate inductance and the approximate capacitance actually measured based on the frequency response, detects the current change and combines the frequency response (the frequency response is more sensitive than the current), avoids that the early failure is not determined due to the slight deformation of the winding which may not cause the change or only cause the slight change of the current, and analyzes the first-order ground coefficient and the first-order open circuit coefficient (approximately the equivalent inductance and the equivalent capacitance, respectively) of the driving point admittance and the ideal equivalent inductance and the capacitance actually measured in the non-working state by the difference function, so as to determine whether the early failure exists, discover the winding failure in time, reduce the downtime and the maintenance cost, improve the service life of the equipment, and improve the overall operation efficiency of the power grid.

[0158] As Figure 3 shown, Figure 3 Fig. 1 is a structural schematic diagram of an embodiment of a transformer winding fault detection system based on current change provided by the application. The transformer winding fault detection system 10 based on current change, the system comprises:

[0159] A current excitation determination module 11 is configured to apply current excitation to the transformer winding, and the current excitation is determined after the normal working current of the transformer winding is scaled by a preset scaling rate.

[0160] A self-induction and mutual induction determination module 12 is configured to determine the self-induction of the transformer winding according to the current excitation and the self-induction coefficient of the transformer winding, and determine the mutual induction of the transformer winding according to the current excitation and the mutual induction coefficient of the transformer winding.

[0161] The equivalent inductance determination module 13 is configured to determine the equivalent inductance according to the self-inductance and the mutual inductance.

[0162] The equivalent capacitance determination module 14 is configured to obtain the series capacitance and ground capacitance of the transformer winding, and determine the equivalent capacitance based on the series capacitance and ground capacitance.

[0163] The first difference function and second difference function determining module 15 is configured to determine the first difference function according to the equivalent inductance and a preset scaling factor, and determine the second difference function according to the equivalent capacitance.

[0164] The fault detection module 16 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.

[0165] In one implementation scenario, in the current excitation determination module 11, current excitation is applied to the transformer winding, and the current excitation can be determined by geometric scaling based on 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 to zoom in or out.

[0166] In the transformer winding self-inductance and mutual inductance determination module 12, self-inductance refers to the electromotive force generated on the transformer winding due to the change of current. That is, when the current passing through a winding changes, the winding itself will induce a reverse electromotive force due to the changing magnetic field. This phenomenon is called self-inductance. 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.

[0167] Induction refers to the phenomenon between two windings close to each other. When the current in one winding changes, it will generate a changing magnetic field, which in turn induces an electromotive force in the other adjacent winding. This phenomenon is called mutual induction. Specifically, the mutual inductance of the transformer winding is determined according to the self-inductance coefficient of different transformer windings and the degree of magnetic coupling between the windings; 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.

[0168] In the equivalent inductance determination module 13, 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.

[0169] In the equivalent capacitance determination module 14, the series capacitance and ground capacitance of the transformer winding are obtained; Determine the equivalent capacitance, where is the equivalent capacitance, is the series capacitor, is the grounding capacitor.

[0170] In the first difference function and second difference function determination module 15, the first-order grounding coefficient and the first-order open-circuit coefficient of the transformer winding are obtained; the first difference function is determined according to the equivalent inductance, the preset scaling factor and the first-order grounding coefficient, and the second difference function is determined according to the equivalent capacitance and the first-order open-circuit coefficient. Specifically, 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.

[0171] In the fault detection module 16, 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, which 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, a transformer winding fault has occurred; 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 fault has not occurred. Therefore, the fault detection module 16 can determine whether there is a fault in the winding by calculating the variation characteristics of the ideal equivalent inductance and ideal equivalent capacitance and the actual measured approximate inductance and actual measured approximate capacitance.

[0172] like Figure 4 As shown, Figure 4A structural schematic diagram of an embodiment of the apparatus provided by the present application. The apparatus 20 comprises a memory 21 and a processor 22. The memory 21 stores a computer program, and the processor 22 executes the computer program when working to implement the method as shown in Figure 1 and Figure 2 .

[0173] The specific technical details of the transformer winding fault detection method based on current change implemented by the apparatus 20 executing the computer program have been described in the foregoing method steps, and thus will not be described again.

[0174] As shown in Figure 5 , Figure 5 A structural schematic diagram of an embodiment of the medium provided by the present application. The medium 30 stores at least a computer program 31, and the computer program 31 is executed by the processor 22 to implement the method as shown in Figure 1 and Figure 2 . The detailed method can be referred to the foregoing, and thus will not be described again. In an embodiment, the medium 30 can be a storage chip, a hard disk or a mobile hard disk or a USB flash disk, an optical disk or other readable and writable storage tools, and can also be a server or the like.

[0175] In addition, the processes depicted in the accompanying drawings do not necessarily have to be implemented in the specific order shown or in a continuous order to achieve the desired results. In some embodiments, multi-task processing and parallel processing are also possible or can be advantageous.

[0176] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly explains the difference from other embodiments. Especially, the device, apparatus and non-volatile computer readable storage medium embodiments are described more simply because they are basically similar to the method embodiments, and the relevant parts can be referred to the part of the method embodiments.

[0177] The device, apparatus, non-volatile computer readable storage medium and method provided by the embodiments of the present application are corresponding, and thus the device, apparatus 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 device, apparatus and non-volatile computer storage medium will not be described again.

[0178] The systems, apparatuses, modules, or units disclosed in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, 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.

[0179] For the sake of description, the above apparatuses are described in various units by functions for description. Of course, the functions of the units can be implemented in one or more software and / or hardware in implementing the present specification. Those skilled in the art should understand that the embodiments of the present specification can be provided as a method, a system, or a computer program product. Therefore, the embodiments of the present specification can be in the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present specification can be in the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, a magnetic disk storage, a CD-ROM, an optical storage, and the like) containing computer-usable program code.

[0180] The present specification is described with reference to flowcharts and / or block diagrams of methods, apparatuses (systems) and computer program products according to embodiments of the present specification. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams 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 apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one or more flows and / or blocks Figure 1 The functions specified in one or more flows and / or blocks

[0181] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one or more flows and / or blocks Figure 1 The functions specified in one or more flows and / or blocks

[0182] These computer program instructions can also be loaded into a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 Figure 1

[0183] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0184] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) about which the computer stores information about an operating system, application software, and / or the like. Memory is an example of computer readable media.

[0185] Computer readable media includes permanent and non-permanent, moveable and non- moveable media that can be implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (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 technology, compact disc read-only memory (CD-ROM), digital versatile disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that is accessible to a computing device. According to the definition provided herein, a computer readable medium does not include transitory media, such as modulated data signals and carrier waves.

[0186] It is also noted that the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0187] ​​The specification can be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, and the like, that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of steps and methods described in this specification is not the only manner in which the methods can be practiced. Likewise, the general description of the sequence of operations above applies to the methods in one or more aspects.

[0188] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, the system embodiments are described simply because they are basically similar to the method embodiments, and the relevant parts can be referred to the description of the method embodiments.

[0189] The above disclosure is merely preferred embodiments of the present application and cannot limit the scope of the present application. Any equivalent changes made according to the claims of the present application are still within the scope of the present application.

Claims

1. A transformer winding fault detection method based on current variation, characterized by, The method comprises: applying a current excitation to the transformer winding, the current excitation being determined after being isotropically scaled according to a normal working current of the transformer winding by a preset scaling rate; determining self-induction of the transformer winding according to the current excitation and a self-induction coefficient of the transformer winding, and determining mutual induction of the transformer winding according to the current excitation and a mutual induction coefficient of the transformer winding; determining equivalent inductance according to the self-induction and the mutual induction; obtaining series capacitance and ground capacitance of the transformer winding, and determining equivalent capacitance according to the series capacitance and the ground capacitance; The first-order ground coefficient and the first-order open circuit coefficient of the transformer winding are acquired; a first difference function is determined according to the equivalent inductance, the preset scaling rate and the first-order ground coefficient, and a second difference function is determined according to the equivalent capacitance and the first-order open circuit coefficient; the first difference function is determined according to the equivalent inductance, the preset scaling rate and the first-order ground coefficient, and the second difference function is determined according to the equivalent capacitance and the first-order open circuit coefficient, specifically comprising: determining a first difference function, wherein, the first difference function is, the equivalent inductance is, the preset scaling rate is, the first-order ground coefficient of the driving point admittance; the second difference function is determined according to determining a second difference function, wherein, the second difference function is, the equivalent capacitance is, the first-order open circuit coefficient of the driving point admittance; detecting a fault of the transformer winding according to a comparison between fluctuations of the first difference function and the second difference function and a preset threshold.

2. A transformer winding fault detection method based on current variation according to claim 1, characterized in that, The determination of the self-induction of the transformer winding according to the current excitation and the self-induction coefficient of the transformer winding, and the determination of the mutual induction of the transformer winding according to the current excitation and the mutual induction coefficient of the transformer winding, specifically comprises: According to determining the self-induction of the transformer winding, wherein the self-induction of the transformer winding is determined by the self-induction of the transformer winding, the self-induction of the transformer winding, the self-induction of the transformer winding, the current excitation; determining the mutual induction coefficient of the transformer winding according to different degrees of magnetic coupling between the self-induction coefficients of the transformer winding and the windings; According to determining a mutual inductance of the transformer windings, wherein a mutual inductance between a first windings and a second windings, a mutual inductance coefficient of a first windings and a second windings, is a current excitation.

3. A transformer winding fault detection method based on current variation according to claim 2, characterized in that, The determination of the equivalent inductance according to the self-induction and the mutual induction specifically comprises: According to determining an equivalent inductance, wherein, is the equivalent inductance, is the mutual inductance between the i-th winding of the transformer and the j-th winding of the transformer, is the mutual inductance between the i-th winding of the transformer and the j-th winding of the transformer, is the self-inductance of the i-th winding of the transformer.

4. The transformer winding fault detection method based on current variation according to claim 1, characterized in that, The obtaining of the series capacitance and the ground capacitance of the transformer winding, and the determination of the equivalent capacitance according to the series capacitance and the ground capacitance specifically comprises: obtaining the series capacitance and the ground capacitance of the transformer winding; According to determining an equivalent capacitance, wherein, is the equivalent capacitance, is a series capacitance, is a ground capacitance.

5. The transformer winding fault detection method based on current variation according to claim 1, characterized in that, The detection of the fault of the transformer winding according to the comparison between the fluctuations of the first difference function and the second difference function and the preset threshold specifically comprises: 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, the preset threshold being 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 the preset threshold, the transformer winding is faulty; if the fluctuation amplitude of the first difference function and the second difference function is less than or equal to the preset threshold, the transformer winding is not faulty.

6. A transformer winding fault detection method based on current variation according to claim 5, characterized in that, The method further comprises: determining a fault level of the transformer winding according to a comparison between fluctuations of the first difference function and / or the second difference function and a preset fault level judgment condition.

7. A transformer winding fault detection system based on current variation, characterized by, The system comprises: a current excitation determination module, configured to apply a current excitation to the transformer winding, the current excitation being determined after being isotropically scaled according to a normal working current of the transformer winding by a preset scaling rate; a self-induction and mutual induction determination module of the transformer winding, configured to determine self-induction of the transformer winding according to the current excitation and a self-induction coefficient of the transformer winding, and determine mutual induction of the transformer winding according to the current excitation and a mutual induction coefficient of the transformer winding; an equivalent inductance determination module, configured to determine equivalent inductance according to the self-induction and the mutual induction; an equivalent capacitance determination module, configured to obtain series capacitance and ground capacitance of the transformer winding, and determine equivalent capacitance according to the series capacitance and the ground capacitance; A first difference function and a second difference function determination module are configured to obtain a first-order grounding coefficient and a first-order open-circuit coefficient of the transformer winding; the first difference function is determined according to the equivalent inductance, the preset scaling rate, and the first-order grounding coefficient, and the second difference function is determined according to the equivalent capacitance and the first-order open-circuit coefficient. The first difference function is determined according to the equivalent inductance, the preset scaling rate, and the first-order grounding coefficient, and the second difference function is determined according to the equivalent capacitance and the first-order open-circuit coefficient, specifically including: determining the first difference function according to the equivalent inductance, the preset scaling rate, and the first-order grounding coefficient, and determining the second difference function according to the equivalent capacitance and the first-order open-circuit coefficient. 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; a fault detection module, configured to detect a fault of the transformer winding according to a comparison between 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, which, when executed by a processor, causes the processor to perform the steps of the method according to any one of claims 1 to 6.

9. A computer device, comprising: A computer program is stored, which, when executed by a processor, causes the processor to perform the steps of the method according to any one of claims 1 to 6.

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