Method and device for determining electromagnetic force distribution of transformer winding and electronic equipment

Abstract

The invention discloses a method and device for determining electromagnetic force distribution of a transformer winding and electronic equipment. The method comprises the following steps: determining geometric parameters of a winding of the transformer; short-circuit currents corresponding to the three phases of the winding respectively under the target closing angle are determined, the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, the short-circuit currents are obtained under the condition that three-phase short circuit still exists after reclosing of the transformer, and reclosing refers to closing of the circuit breaker, disconnected due to the fault, of the transformer; and on the basis of the geometric parameters and the short-circuit current corresponding to the three phases, electromagnetic force distribution corresponding to the three phases of the winding at the target closing angle is determined. The technical problem that the electromagnetic force distribution determination result of the transformer winding is inaccurate after the transformer is reclosed in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of power systems, and more specifically, to a method, apparatus, and electronic device for determining the electromagnetic force distribution of a transformer winding. Background Technology

[0002] In actual power system operation, after a transformer experiences an initial short circuit, power supply can be restored via automatic reclosing. However, because the system may not be able to eliminate the short circuit fault in time, the transformer will be subjected to a secondary short-circuit current surge again shortly after reclosing. Simultaneously, during the current-free interval when the circuit breaker is open, the residual magnetism in the core significantly influences the secondary short-circuit current, increasing the secondary short-circuit current after reclosing and the electromagnetic force on the transformer windings. This can lead to axial and radial displacement, twisting, or instability of the windings, threatening the structural integrity of the transformer and the stability of the power system.

[0003] Related technologies employ static analysis to determine the electromagnetic force distribution of transformer windings under short-circuit conditions after reclosing. However, this method fails to adequately consider the dynamic changes in short-circuit current and magnetic field during reclosing, particularly the influence of residual magnetism within the core, leading to inaccurate predictions of the winding's electromagnetic force. Therefore, related technologies suffer from the technical problem of inaccurate determination of the electromagnetic force distribution of transformer windings after reclosing.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This application provides a method, apparatus, and electronic device for determining the electromagnetic force distribution of a transformer winding, in order to at least solve the technical problem in the related art of inaccurate determination of the electromagnetic force distribution of the transformer winding after transformer reclosing.

[0006] According to one aspect of the embodiments of this application, a method for determining the electromagnetic force distribution of a transformer winding is provided, comprising: determining the geometric parameters of the transformer winding; determining the short-circuit currents corresponding to the three phases of the winding at a target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained under the condition that a three-phase short circuit still exists after the transformer is reclosed, and reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; and determining the electromagnetic force distribution corresponding to the three phases of the winding at the target closing angle based on the geometric parameters and the short-circuit currents corresponding to the three phases.

[0007] According to another aspect of the embodiments of this application, an electromagnetic force distribution determination device for a transformer winding is provided, comprising: a geometric parameter determination module for determining the geometric parameters of the transformer winding; a short-circuit current determination module for determining the short-circuit currents corresponding to the three phases of the winding at a target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained under the condition that a three-phase short circuit still exists after the transformer is reclosed, and reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; and an electromagnetic force distribution determination module for determining the electromagnetic force distribution corresponding to the three phases of the winding at the target closing angle based on the geometric parameters and the short-circuit currents corresponding to the three phases.

[0008] According to another aspect of the embodiments of this application, a non-volatile storage medium is provided, which stores multiple instructions, any one of which is adapted to be loaded by a processor for determining the electromagnetic force distribution of a transformer winding.

[0009] According to another aspect of the embodiments of this application, an electronic device is provided, including: one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement any one of the methods for determining the electromagnetic force distribution of a transformer winding.

[0010] According to another aspect of the embodiments of this application, a computer program product is provided, which, when executed on a data processing device, is adapted to perform the steps of a method for determining the electromagnetic force distribution of a transformer winding.

[0011] In this embodiment, the geometric parameters of the transformer windings are determined; the short-circuit currents corresponding to the three phases of the windings are determined at the target closing angle, where the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained under the condition that a three-phase short circuit still exists after the transformer is reclosed; reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; based on the geometric parameters and the corresponding short-circuit currents of the three phases, the electromagnetic force distribution of the three phases of the windings is determined at the target closing angle. This achieves the goal of determining the electromagnetic force distribution of the windings based on the geometric parameters of the transformer windings and the short-circuit currents of the windings under three-phase short-circuit conditions at the target closing angle, thereby improving the accuracy of the determination result of the electromagnetic force distribution of the transformer windings at the target closing angle after transformer reclosing, and solving the technical problem of inaccurate determination results of the electromagnetic force distribution of the transformer windings after transformer reclosing in related technologies. Attached Figure Description

[0012] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0013] Figure 1 This is a flowchart of a method for determining the electromagnetic force distribution of a transformer winding according to an embodiment of this application;

[0014] Figure 2 This is a schematic diagram of an optional transformer reclosing circuit model provided according to an embodiment of this application;

[0015] Figure 3 This is a schematic diagram of the current variation of an optional winding according to an embodiment of this application;

[0016] Figure 4 This is a schematic diagram of an optional three-dimensional finite element simulation model of a transformer's magnetic-circuit-force according to an embodiment of this application;

[0017] Figure 5 This is a schematic diagram of an optional core BH curve provided according to an embodiment of this application;

[0018] Figure 6 This is an optional mesh partitioning diagram provided according to an embodiment of this application;

[0019] Figure 7 This is a flowchart of an optional method for determining the electromagnetic force distribution of a transformer winding according to an embodiment of this application;

[0020] Figure 8 This is a schematic diagram of an optional electromagnetic force distribution determination device for transformer windings provided according to an embodiment of this application. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] According to an embodiment of this application, a method embodiment for determining the electromagnetic force distribution of a transformer winding is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0024] Figure 1 This is a flowchart of a method for determining the electromagnetic force distribution of a transformer winding according to an embodiment of this application, as shown below. Figure 1 As shown, the method includes the following steps:

[0025] Step S102: Determine the geometric parameters of the transformer windings;

[0026] It is understandable that determining the geometric parameters of the transformer windings, including the number of turns and conductor length, is crucial. Accurately determining these parameters improves the accuracy of the determination of the electromagnetic force distribution influenced by the winding geometry.

[0027] Step S104: Determine the short-circuit currents corresponding to the three phases of the winding at the target closing angle. The closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed. The short-circuit current is obtained when there is still a three-phase short circuit after the transformer is reclosed. Reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault.

[0028] It is understandable that a transformer can restore power supply after a three-phase short-circuit fault by reclosing, i.e., closing the circuit breaker that was disconnected due to the fault. If the three-phase short-circuit fault is not resolved within the time the circuit breaker is open, short-circuit current will still exist in the windings after reclosing. Therefore, to determine the electromagnetic force distribution of the windings at the target closing angle, it is first necessary to determine the corresponding short-circuit currents for each of the three phases of the windings at that angle. By determining the short-circuit currents of the windings at the target closing angle, the problem of inaccurate determination of the electromagnetic force distribution of the transformer windings after reclosing can be effectively solved, thereby optimizing transformer design and power system protection strategies, and significantly improving the safety and operating efficiency of the power system.

[0029] Optionally, the three phases of the winding refer to the A-phase winding, B-phase winding, and C-phase winding of the three-phase winding. For the above three windings of the transformer, the electrical balance and magnetic circuit symmetry of the transformer can be ensured by keeping the parameters such as the number of turns, material, and wire length of the three windings the same.

[0030] Alternatively, the short-circuit currents corresponding to the three phases of the winding can be determined by building a transformer reclosing circuit model. Figure 2 This is a schematic diagram of an optional transformer reclosing circuit model provided according to an embodiment of this application, such as... Figure 2 The figure shows a transformer reclosing line model built based on a 110kV (kilovolt) full-scale transformer. The parameters of the transformer are shown in Table 1.

[0031] Table 1 Transformer Parameters

[0032]

[0033] Optionally, taking phase A winding as an example, this section explains how to determine the short-circuit currents corresponding to the three phases of the winding after reclosing under different short-circuit fault conditions. The reclosing process time can be set as follows: 0s~0.1s (seconds) for normal transformer operation; a three-phase short circuit occurs at 0.1s; the circuit breaker trips and disconnects the power supply at 0.5s~0.6s; at this time, the closing angle of phase A winding is 0°. If the fault is not successfully cleared during this period, the circuit breaker recloses at 0.6s; at this time, the closing angle of phase A winding is 0°. This can be achieved using methods such as... Figure 2 The transformer reclosing circuit model shown is used to analyze the current change of phase A winding during the above process. Figure 3 This is a schematic diagram illustrating the current variation of an optional winding according to an embodiment of this application, such as... Figure 3 The diagram shows the current change in phase A winding during the above process. Figure 3It can be seen that the secondary short-circuit current reaches its peak value of 3538A (amperes) 0.01s after reclosing, which is slightly greater than the primary short-circuit current of 3505A. This is because the core of the transformer exhibits a hysteresis effect, meaning that after the core is magnetized by an external magnetic field, even if the external magnetic field is removed, the magnetization state within the core cannot immediately return to its original state, but exhibits a certain lag. When the circuit breaker is opened, due to the hysteresis effect of the core, the residual magnetism cannot disappear in a short time. Therefore, during reclosing, the residual magnetism in the core will superimpose with the excitation vector. When the residual magnetism and the excitation vector are in the same direction, the secondary short-circuit current will be greater than the primary short-circuit current.

[0034] Optionally, adopt Figure 2 The transformer reclosing circuit model can determine not only the short-circuit current of a three-phase short circuit, but also the short-circuit current of the winding under other short-circuit fault conditions. The short-circuit current in phase A winding after reclosing is calculated and analyzed under other permanent short-circuit fault conditions. Table 2 shows the amplitude of the secondary short-circuit current of phase A winding under different short-circuit fault conditions. By comparing the magnitudes of the secondary short-circuit current of phase A winding under different short-circuit conditions in Table 2, it can be concluded that the secondary short-circuit current of phase A winding is the largest under three-phase short-circuit conditions.

[0035] Table 2. Amplitude of secondary short-circuit current of phase A winding under different short-circuit fault conditions.

[0036]

[0037] In one optional embodiment, determining the short-circuit currents corresponding to the three phases of the winding at the target closing angle includes: for any one phase of the three phases, determining the integral constant, angular frequency, first line impedance angle, and first steady-state short-circuit current amplitude of that phase, wherein the integral constant is determined based on the state of the series circuit in which the winding is located before the circuit breaker is closed, the angular frequency is used to describe the rate of change of any short-circuit current of any phase with time, the first line impedance angle is used to describe the ratio of resistance to reactance in the series circuit after reclosing, and the first steady-state short-circuit current amplitude refers to the maximum instantaneous amplitude of the AC current in the winding when the current in the series circuit no longer changes with time after reclosing; determining any short-circuit current of any phase based on the integral constant, angular frequency, first line impedance angle, first steady-state short-circuit current amplitude, and target closing angle; and determining the short-circuit currents corresponding to the three phases by using the method of determining any short-circuit current.

[0038] It is understandable that, for any phase of the three-phase winding, to determine any short-circuit current in any phase, it is first necessary to determine the integral constant, angular frequency, first line impedance angle, and first steady-state short-circuit current amplitude of any phase. The integral constant is determined based on the state of the series circuit in which the winding is located before the circuit breaker closes. The angular frequency describes the rate of change of any short-circuit current in any phase over time. The first line impedance angle refers to the ratio of resistance to reactance in the series circuit after reclosing. The first steady-state short-circuit current amplitude refers to the maximum instantaneous amplitude of the AC current in the winding when the current in the series circuit no longer changes over time after reclosing. Based on the integral constant, angular frequency, first line impedance angle, first steady-state short-circuit current amplitude, and target closing angle, the short-circuit current of any phase is calculated. By determining the short-circuit current of any phase, the short-circuit currents corresponding to the three phases of the winding are determined. This method improves the accuracy of determining the short-circuit currents corresponding to the three phases of the winding, thereby improving the accuracy of determining the electromagnetic force distribution of the winding.

[0039] Optionally, when a transformer experiences a sudden short circuit, the circuit breaker is disconnected after the relay protection operates, and reclosing is performed after setting. Ideally, the fault is cleared after the relay protection operates, and the reclosing is successful, allowing the transformer to be put back into operation. However, if the short-circuit fault is not cleared in time, the transformer will be subjected to the impact of the short-circuit current again after reclosing. Furthermore, due to the hysteresis effect of the core, the residual magnetism cannot disappear in a short time during opening. Therefore, the residual magnetism will superimpose with the excitation vector during reclosing, resulting in a secondary short-circuit current greater than the primary short-circuit current.

[0040] In one optional embodiment, determining the integral constant of any phase includes: determining the second steady-state short-circuit current amplitude of any phase before reclosing, and the second line impedance angle of any phase before reclosing; and determining the integral constant based on the second steady-state short-circuit current amplitude and the second line impedance angle.

[0041] It is understandable that the integral constant of any phase can be determined as follows: First, determine the second steady-state short-circuit current amplitude and the second line impedance angle of any phase before reclosing. Based on the aforementioned second steady-state short-circuit current amplitude and second line impedance angle, determine the integral constant of any phase. Calculating the integral constant in this way takes into account the transient characteristics of the current, improves the accuracy of the calculation results for any short-circuit current in any phase, and thus improves the accuracy of the determination results for the electromagnetic force distribution of the winding.

[0042] Optionally, the analysis can be conducted using the case where a three-phase short-circuit fault still exists after reclosing as an example, calculating the short-circuit currents corresponding to the three phases of the winding after reclosing. Both the sudden three-phase short-circuit fault and the reclosing process of the transformer are current state response problems of an RL series circuit, with identical equivalent circuits, and the three-phase short circuit is symmetrical. Therefore, the analysis will take the A-phase winding as an example to illustrate how to determine the short-circuit currents corresponding to the three phases of the winding. The short-circuit current i of the A-phase winding... a (t) can be determined in the following way:

[0043]

[0044] Solving the above formula, we get:

[0045]

[0046] in, Indicates the first line impedance angle; I m The first steady-state short-circuit current amplitude is represented by C; the integration constant is represented by α; the target closing angle is represented by L; the inductance of the series circuit is represented by R; the resistance of the series circuit is represented by t; and U represents time. m The voltage represents the maximum value of the power supply voltage; ω represents the angular frequency; T a This is the decay time constant.

[0047] Optionally, since the short-circuit current of phase A winding after reclosing is significantly affected by residual magnetism, and the closing angle varies at different closing times due to different relay protection setting times, the current cannot change abruptly for the RL circuit to which the winding belongs. Therefore, the short-circuit current of phase A winding at the instant of reclosing can be determined as follows:

[0048]

[0049] in, Indicates the second line impedance angle; I m|0| This represents the amplitude of the second steady-state short-circuit current.

[0050] Alternatively, the integration constant C can be determined as follows:

[0051]

[0052] By solving the above formula, we can obtain:

[0053]

[0054] Optionally, since the current before closing is 0, i.e., I m|0| =0, and the reactance in the short-circuit loop is much greater than the resistance, that is The short-circuit current of phase A winding can be determined as follows:

[0055]

[0056] Optionally, the short-circuit currents corresponding to the three phases of the winding at different closing angles can be obtained by changing the closing angle. The short-circuit currents corresponding to the three phases of the winding at different closing angles are shown in Table 3.

[0057] Table 3. Short-circuit currents of the three phases of the winding at different closing angles.

[0058]

[0059] Table 3 shows that the short-circuit currents of the three phases of the winding change to varying degrees under different closing angles compared to the initial closing angle. Furthermore, due to the fixed phase difference between the three phases, the monotonicity of different phases varies during the same period, meaning that at least one phase experiences a decrease in the amplitude of its secondary short-circuit current under the influence of residual magnetism. When the closing angle is 0°, the maximum amplitude of the secondary short-circuit current in the three-phase winding is 3538A, the highest compared to other closing angles. Conversely, when the closing angle is 90°, the maximum amplitude of the secondary short-circuit current in the three-phase winding is 3379A, the lowest compared to other closing angles. Therefore, properly configuring the reclosing time can significantly reduce the secondary short-circuit current and mitigate its harmful effects on the transformer and power system.

[0060] Step S106: Based on the geometric parameters and the short-circuit currents corresponding to the three phases, determine the electromagnetic force distribution of the three phases of the winding at the target closing angle.

[0061] It is understandable that, based on the geometric parameters of the winding and the short-circuit currents corresponding to the three phases of the winding, the electromagnetic force distribution corresponding to the three phases of the winding at the target closing angle can be determined. Accurate calculation of the electromagnetic force distribution can provide a scientific basis for optimizing the structure of the transformer winding, help assess and enhance the mechanical strength of the winding, and prevent instability under extreme operating conditions.

[0062] In one optional embodiment, based on geometric parameters and the short-circuit currents corresponding to the three phases respectively, the electromagnetic force distribution of the winding corresponding to the three phases at the target closing angle is determined, including: for any one of the three phases, based on geometric parameters and any short-circuit current of any one phase, the electromagnetic force distribution of the winding in any one phase is determined; the electromagnetic force distribution corresponding to the three phases is determined by using the method of determining the electromagnetic force distribution of any one phase.

[0063] It is understandable that, for any one of the three phases of the winding, the electromagnetic force distribution of that phase is determined based on the winding's geometric parameters and any short-circuit current in that phase. By determining the electromagnetic force distribution of any one phase, the electromagnetic force distribution corresponding to each of the three phases of the winding can be determined. Quantifying the electromagnetic force distribution of the winding under a target closing angle provides maintenance personnel with a basis for assessing the transformer winding's health and developing maintenance plans, thereby enabling the development of more reasonable and precise reclosing strategies, such as determining the closing angle when the transformer recloses.

[0064] In one optional embodiment, the electromagnetic force distribution of the winding in any phase is determined based on geometric parameters and any short-circuit current of any phase, including: determining the leakage magnetic field distribution of any phase based on geometric parameters, material information of the winding, and any short-circuit current, wherein the leakage magnetic field distribution is used to describe the variation law of magnetic field strength and magnetic flux density in the space surrounding the winding; and determining the electromagnetic force distribution based on geometric parameters, any short-circuit current, and leakage magnetic field distribution.

[0065] It is understandable that a three-dimensional finite element simulation model of the winding can be constructed based on the winding's geometric parameters and material information. Using this simulation model, the leakage flux distribution of any phase, describing the variation of magnetic field strength and magnetic flux density in the space surrounding the winding, can be determined based on any short-circuit current in any phase and the leakage flux distribution of any phase. The electromagnetic force distribution of any phase of the winding can then be determined based on the winding's geometric parameters, any short-circuit current in any phase, and the leakage flux distribution of any phase. Through this method, the electromagnetic force distribution and stress state of the winding at the target closing angle can be accurately determined, thereby enabling the assessment of the transformer winding's structural strength and preventing mechanical deformation and structural damage that may be caused by short-circuit impacts, such as axial instability and radial instability.

[0066] In an optional embodiment, when the leakage magnetic field distribution includes axial leakage magnetic field distribution and radial leakage magnetic field distribution, and the electromagnetic force distribution includes axial electromagnetic force distribution and radial electromagnetic force distribution, the electromagnetic force distribution is determined based on geometric parameters, any short-circuit current, and leakage magnetic field distribution. This includes: determining the radial electromagnetic force distribution based on geometric parameters, any short-circuit current, and axial leakage magnetic field distribution, wherein the axial leakage magnetic field distribution is used to describe the variation law of the magnetic field strength of the winding in the axial direction, and the axial direction refers to the direction of the central axis of the winding; and determining the axial electromagnetic force distribution based on geometric parameters, any short-circuit current, and radial leakage magnetic field distribution, wherein the radial leakage magnetic field distribution is used to describe the variation law of the magnetic field strength of the winding in the radial direction, and the radial direction refers to the radial direction of the winding perpendicular to the axial direction.

[0067] It can be understood that decomposing the leakage flux distribution of any phase yields the axial and radial leakage flux distributions for that phase. The axial leakage flux distribution describes the variation of the magnetic field strength in the axial direction (i.e., the direction of the winding's central axis), while the radial leakage flux distribution describes the variation of the magnetic field strength in the radial direction (i.e., the radial direction of the winding perpendicular to the axial direction). Based on the winding's geometric parameters, any short-circuit current in any phase, and the axial leakage flux distribution, the radial electromagnetic force distribution of any phase can be determined. Similarly, based on the winding's geometric parameters, any short-circuit current in any phase, and the radial leakage flux distribution, the axial electromagnetic force distribution of any phase can be determined. By comprehensively utilizing the winding's geometric parameters, the short-circuit current of any phase, and the leakage flux distribution of any phase, accurate calculations of the axial and radial electromagnetic force distributions of the winding can be achieved under target reclosing conditions. This can then guide transformer design and optimize power system maintenance strategies, improving the safety and reliability of the power system.

[0068] Optionally, a three-dimensional finite element simulation model of the transformer's magnetic-circuit-force system can be built using the finite element method to calculate the electromagnetic force distribution corresponding to the three phases of the winding, thereby quantifying the impact of different closing angles on the transformer winding. Taking a three-phase, three-limb transformer as an example, a three-dimensional finite element simulation model of the magnetic-circuit-force system is established. For ease of study, the model is simplified as follows:

[0069] 1) Due to the magnetic permeability of their own materials, structural components such as clamps and pull plates have little impact on the leakage magnetic field distribution. Therefore, structural components such as winding supports, pull plates, and clamps are ignored.

[0070] 2) Assume that the height of the high, medium and low voltage windings is the same and the coils are evenly distributed, and the windings adopt a cylindrical structure.

[0071] Optionally, Figure 4 This is a schematic diagram of an optional three-dimensional finite element simulation model of a transformer's magnetic-circuit-force according to an embodiment of this application. Figure 4 The three-dimensional finite element simulation model was constructed based on the main parameters of the transformer shown in Table 4.

[0072] Table 4 Main Parameters of Transformer

[0073]

[0074]

[0075] Optionally, in the aforementioned three-dimensional finite element simulation model of the transformer's magnetic-circuit-force system, the core material is silicon steel sheet, composed of multiple layers of thin silicon steel sheets, which provides more accurate calculations compared to a core column formed by integral stretching. The winding adopts a cylindrical, uniformly distributed multi-turn configuration, and the material is copper wire. The air domain outside the core and winding is... Figure 4The information is hidden during the process. The material information settings for the core and windings are shown in Table 5.

[0076] Table 5 Winding Material Information and Core Material Information

[0077]

[0078] Optionally, Figure 5 This is a schematic diagram of an optional BH curve of an iron core provided according to an embodiment of this application. Due to the magnetization saturation effect of the iron core, the iron core is supplemented with... Figure 5 The BH curve is shown. The horizontal axis represents magnetic field strength, in A / m (amperes per meter); the vertical axis represents magnetic flux density, in T (tesla). Figure 5 As shown, when the iron core is initially subjected to an external magnetic field, the magnetic domains inside it tend to align with the direction of the external magnetic field, thus making the iron core as a whole exhibit a magnetized state, and the magnetic induction intensity of the iron core also increases accordingly; however, when the external magnetic field reaches a certain intensity, all the magnetic domains in the iron core are almost completely aligned with the direction of the external magnetic field. At this point, even if the intensity of the external magnetic field is further increased, the magnetization degree of the iron core will not increase significantly, and consequently, the magnetic induction intensity of the iron core will no longer increase.

[0079] Alternatively, the model can be divided into regions and meshed to balance the accuracy and efficiency of solving the magnetic-circuit-force three-dimensional finite element simulation model. Figure 6 This is an optional mesh partitioning diagram provided according to an embodiment of this application. The winding portion is formed by dividing the end face into triangular meshes and sweeping along the axial direction, as shown in the diagram. Figure 6 Region 1 in the diagram; the meshing method for the empty channel is the same as that for the winding, but because the empty channel is relatively narrow, the mesh size needs to be adjusted to suit the calculation requirements. After meshing the empty channel, the resulting structure is as follows: Figure 6 Region 2 in the diagram; due to the thickness limitation of the silicon steel sheets, the core section must be divided into finer grids, resulting in a core section that resembles... Figure 6 The three regions in the text.

[0080] Optionally, when a short-circuit current passes through the winding, it generates a leakage magnetic field in the surrounding space. Taking phase A winding as an example, this explains how to determine the leakage magnetic field distribution (i.e., leakage magnetic field distribution) for each of the three phases of the winding. According to... Figure 3It can be seen that at 0.01s after the three-phase short circuit, the short-circuit current of phase A winding is the largest, and at this time, the leakage magnetic field and the electromagnetic force around phase A winding are also the largest. At 0.01s, the magnetic flux density of the leakage magnetic field is mainly concentrated in the empty channel of phase A winding, therefore, the value at the center of the empty channel is the largest, reaching 2T. Since the leakage magnetic field distribution of phase A winding at this time is the superposition of axial leakage magnetic field distribution and radial leakage magnetic field distribution, for ease of analysis, the leakage magnetic field distribution of phase A winding is decomposed into axial leakage magnetic field distribution and radial leakage magnetic field distribution. The axial leakage magnetic field distribution of phase A winding shows that the magnetic flux density is axially symmetrical about the height of phase A winding, accounting for the majority of the main leakage magnetic field in the empty channel. The axial leakage magnetic field at the ends of phase A winding decreases with the change of magnetic field direction, with the maximum value at the center position. If the middle of the winding is taken as the origin, the direction and trend of the axial leakage magnetic field at the upper and lower ends are consistent, and the magnetic flux density decreases the farther away from the middle of the winding.

[0081] Optionally, the radial leakage flux distribution of phase A winding shows that the radial leakage flux of phase A winding is centrally symmetrically distributed along the center of the core column, with the two ends being larger and the middle smaller, and the radial leakage flux density at the center height being 0. In the axial height, with the center of phase A winding as the origin, the directions of the radial leakage flux density at the upper and lower parts are opposite. The farther away from the center of phase A winding, the greater the radial leakage flux density, and it is mainly generated at the winding ends.

[0082] Optionally, during transformer short-circuit operation, the windings are subjected to short-circuit electromagnetic forces. The axial electromagnetic force distribution of phase A winding is determined by the product of the radial leakage flux distribution and the short-circuit current of phase A winding; the radial electromagnetic force distribution of phase A winding is determined by the product of the axial leakage flux distribution and the short-circuit current of phase A winding. The axial electromagnetic force F of phase A winding... z The radial electromagnetic force F of phase A winding r It can be determined in the following way:

[0083] F z =B r ILW

[0084] F r =B z ILW

[0085] Optionally, during the initial short circuit, the radial magnetic induction at the middle of phase A winding is almost zero, so no axial electromagnetic force is generated in the middle. The electromagnetic force generated at the ends of phase A winding is the largest and in the opposite direction, with a maximum value of 9.55 × 10⁻⁶. 6 N / m3 (Newtons per cubic meter), therefore, the A-phase winding will still experience axial instability due to the axial electromagnetic force. When the axial electromagnetic force of the A-phase winding is too large, it will cause the transformer's A-phase winding to collide and rub against the structural components, resulting in insulation damage to the conductor turns and ultimately axial instability.

[0086] Optionally, during the initial short circuit, the radial electromagnetic force induced in the middle of phase A winding is the largest, reaching 2.77 × 10⁻⁶. 7 The electromagnetic forces generated at the top and bottom of the transformer are symmetrically distributed about the center height of phase A winding. When the radial electromagnetic force reaches a certain average critical value, phase A winding will experience radial instability. In severe cases, this can lead to the breakage of the turn insulation of phase A winding, causing inter-turn short circuits. Under the combined action of axial and radial electromagnetic forces, the pads will shrink and shift, and the conductors will loosen or tilt. Repeated short-circuit impacts can lead to insulation failure, ultimately causing serious transformer operation accidents.

[0087] Through the above steps S102 to S106, the electromagnetic force distribution of the transformer winding can be determined based on the geometric parameters of the transformer winding and the short-circuit current of the winding at the target closing angle under three-phase short-circuit conditions. This achieves the technical effect of improving the accuracy of the determination result of the electromagnetic force distribution of the transformer winding at the target closing angle after the transformer is reclosed, thereby solving the technical problem of inaccurate determination result of the electromagnetic force distribution of the transformer winding after the transformer is reclosed in related technologies.

[0088] Based on the above embodiments and optional embodiments, this application proposes an implementation method for determining the electromagnetic force distribution of a transformer winding, which can be understood as a simulation calculation method for electromagnetic force under transformer reclosing conditions. First, a transformer reclosing circuit model is built to simulate the reclosing condition after a sudden permanent short-circuit fault. The primary short-circuit currents corresponding to the three phases of the winding and the secondary short-circuit currents (i.e., short-circuit currents) corresponding to the three phases of the winding under different closing angles and residual magnetism are calculated and compared. Second, a three-dimensional finite element simulation model of the transformer's magnetic-circuit-force is established. The impact currents (i.e., short-circuit currents) corresponding to the three phases of the winding under multiple different closing angles after reclosing are calculated through the simulation circuit. These are used as excitation inputs to the three-dimensional finite element simulation model of the magnetic-circuit-force, and then coupled calculations are performed to obtain the leakage flux distribution and electromagnetic force distribution corresponding to the three phases of the winding. Through the above process, the short-circuit currents corresponding to the three phases of the winding under different closing angles and the electromagnetic force distribution corresponding to the three phases of the winding can be analyzed and quantified. Figure 7 This is a flowchart of an optional method for determining the electromagnetic force distribution of a transformer winding according to an embodiment of this application, as shown below. Figure 7 As shown, the steps of this method include:

[0089] Step S1: Building the transformer reclosing circuit model.

[0090] Based on a 110kV (kilovolt) full-scale transformer, the following is constructed: Figure 2 The transformer reclosing circuit model shown is illustrated in Table 1, where the transformer parameters are as shown in Table 1.

[0091] Taking phase A winding as an example, this section explains how to determine the short-circuit currents of the three phases in the winding after reclosing under different short-circuit fault conditions. The reclosing process time is set as follows: 0s~0.1s (seconds) for normal transformer operation; a three-phase short circuit occurs at 0.1s; the circuit breaker trips and disconnects the power supply at 0.5s~0.6s. At this time, the closing angle of phase A winding is 0°. During this period, the fault is not successfully cleared; the circuit breaker recloses at 0.6s, and the closing angle of phase A winding is 0°. The following method is used... Figure 2 The transformer reclosing circuit model shown is used to analyze the current change of phase A winding during the above process. The current change process of phase A winding during the above process is as follows: Figure 3 As shown. By Figure 3 It can be seen that the secondary short-circuit current reaches its peak value of 3538A (amperes) 0.01s after reclosing, which is slightly greater than the primary short-circuit current of 3505A. This is because the core of the transformer exhibits a hysteresis effect, meaning that after the core is magnetized by an external magnetic field, even if the external magnetic field is removed, the magnetization state within the core cannot immediately return to its original state, but exhibits a certain lag. When the circuit breaker is opened, due to the hysteresis effect of the core, the residual magnetism cannot disappear in a short time. Therefore, during reclosing, the residual magnetism in the core will superimpose with the excitation vector. When the residual magnetism and the excitation vector are in the same direction, the secondary short-circuit current will be greater than the primary short-circuit current.

[0092] use Figure 2 A transformer reclosing circuit model was used to calculate and analyze the short-circuit current in phase A winding after reclosing under other permanent short-circuit fault conditions. Table 2 shows the amplitude of the secondary short-circuit current in phase A winding under different short-circuit fault conditions.

[0093] By comparing the magnitudes of the secondary short-circuit current of phase A winding under different short-circuit conditions in Table 2, it can be concluded that the secondary short-circuit current of phase A winding is the largest under three-phase short-circuit conditions. Next, we analyze and calculate the influence of the closing angle on the three-phase short-circuit current of the winding under three-phase short-circuit conditions.

[0094] Step S2: Analysis of the short-circuit currents of the three phases of the winding at different closing angles during a three-phase short circuit.

[0095] When a transformer experiences a sudden short circuit, the circuit breaker is tripped after the relay protection system operates, and reclosing is performed after the settings are completed. Ideally, the fault is cleared after the relay protection system operates, the reclosing is successful, and the transformer is put back into operation. However, if the short-circuit fault is not cleared in time, the transformer will be subjected to another short-circuit current after reclosing. Furthermore, due to the hysteresis effect of the core, the residual magnetism cannot disappear quickly during tripping. Therefore, the residual magnetism will superimpose with the excitation vector during reclosing, resulting in a secondary short-circuit current greater than the primary short-circuit current.

[0096] Taking the case where a three-phase short-circuit fault persists after reclosing as an example, this paper analyzes and calculates the short-circuit currents corresponding to the three phases of the winding after reclosing. Both the sudden three-phase short-circuit fault and the reclosing process of a transformer are current state response problems of an RL series circuit, with identical equivalent circuits, and the three-phase short circuit is symmetrical. Therefore, taking the A-phase winding as an example, this paper explains how to determine the short-circuit currents corresponding to the three phases of the winding. The short-circuit current i of the A-phase winding... a The method for determining (t) is the same as in the above embodiments, and will not be repeated here.

[0097] Because the short-circuit current of phase A winding is significantly affected by residual magnetism after reclosing, and because the relay protection setting time varies, the closing angle also differs under different closing times. The following determines the calculation method for the short-circuit current of phase A winding under different closing angles.

[0098] For the RL circuit to which the winding belongs, the current cannot change abruptly. At the instant of reclosing, the short-circuit current i of phase A winding... a The method for determining (0) is the same as in the above embodiments, and will not be repeated here.

[0099] The method for determining the integration constant C is the same as in the above embodiments, and will not be repeated here.

[0100] Since the current before closing is 0, i.e., I m|0| =0, and the reactance in the short-circuit loop is much greater than the resistance, that is At this time, the short-circuit current i of phase A winding a The method for determining (t) is the same as in the above embodiments, and will not be repeated here.

[0101] The short-circuit currents of the three phases of the winding at different closing angles obtained by changing the closing angle are shown in Table 3.

[0102] Table 3 shows that the short-circuit currents of the three phases of the winding change to varying degrees under different closing angles compared to the initial closing angle. Furthermore, due to the fixed phase difference between the three phases, the monotonicity of different phases varies during the same period, meaning that at least one phase experiences a decrease in the amplitude of its secondary short-circuit current under the influence of residual magnetism. When the closing angle is 0°, the maximum amplitude of the secondary short-circuit current in the three-phase winding is 3538A, the highest compared to other closing angles. Conversely, when the closing angle is 90°, the maximum amplitude of the secondary short-circuit current in the three-phase winding is 3379A, the lowest compared to other closing angles. Therefore, properly configuring the reclosing time can significantly reduce the secondary short-circuit current and mitigate its harmful effects on the transformer and power system.

[0103] To quantify the impact of different closing angles on transformer windings, a three-dimensional finite element simulation model of the transformer's magnetic-circuit-force system was built using the finite element method to calculate the electromagnetic force distribution corresponding to the three phases of the winding.

[0104] Step S3 involves building a three-dimensional finite element simulation model of the transformer's magnetic-circuit-force system and calculating the electromagnetic force distribution corresponding to the three phases of the winding.

[0105] Taking a three-phase, three-limb transformer as an example, establish as follows Figure 4 The magnetic-circuit-force three-dimensional finite element simulation model shown is as follows: Figure 4 The main parameters of the transformer in the three-dimensional finite element simulation model of magnetic-circuit-force are shown in Table 4.

[0106] For ease of study, the model is simplified as follows:

[0107] 1) Due to the magnetic permeability of their own materials, structural components such as clamps and pull plates have little impact on the leakage magnetic field distribution. Therefore, structural components such as winding supports, pull plates, and clamps are ignored.

[0108] 2) Assume that the height of the high, medium and low voltage windings is the same and the coils are evenly distributed, and the windings adopt a cylindrical structure.

[0109] In the aforementioned three-dimensional finite element simulation model of the transformer's magnetic circuit and force, the core material is silicon steel sheet, composed of multiple layers of thin silicon steel sheets, which provides more accurate calculations compared to a core column formed by integral stretching. The winding adopts a cylindrical, uniformly distributed multi-turn configuration, and the material is copper wire. The air domain outside the core and windings is... Figure 4 The information is hidden during the process. The material information settings for the core and windings are shown in Table 5.

[0110] Adding such to the iron core Figure 5 The BH curve is shown. The horizontal axis represents magnetic field strength, in A / m; the vertical axis represents magnetic flux density, in T (Tesla). Figure 5 As shown, when the iron core is initially subjected to an external magnetic field, the magnetic domains inside it tend to align with the direction of the external magnetic field, thus making the iron core as a whole exhibit a magnetized state, and the magnetic induction intensity of the iron core also increases accordingly; however, when the external magnetic field reaches a certain intensity, all the magnetic domains in the iron core are almost completely aligned with the direction of the external magnetic field. At this point, even if the intensity of the external magnetic field is further increased, the magnetization degree of the iron core will not increase significantly, and consequently, the magnetic induction intensity of the iron core will no longer increase.

[0111] To balance accuracy and efficiency in solving the three-dimensional finite element simulation model of magnetic circuit-force, the model is meshed in different regions. For the winding section, the end faces are divided into triangular meshes and swept along the axial direction to form a mesh like... Figure 6 Region 1 in the diagram; the meshing method for the empty channel is the same as that for the winding, but because the empty channel is relatively narrow, the mesh size needs to be adjusted to suit the calculation requirements. After meshing the empty channel, the resulting structure is as follows: Figure 6Region 2 in the diagram; due to the thickness limitation of the silicon steel sheets, the core section must be divided into finer grids, resulting in a core section that resembles... Figure 6 The three regions in the text.

[0112] When a short-circuit current passes through the winding, it generates a leakage magnetic field in the surrounding space. To study the internal leakage magnetic field distribution (i.e., leakage magnetic field distribution) of a transformer under a three-phase short-circuit condition, this paper takes the A-phase winding as an example to illustrate how to determine the leakage magnetic field distribution corresponding to each of the three phases of the winding. Figure 3 It can be seen that at 0.01s after the three-phase short circuit, the short-circuit current of phase A winding is the largest. At this time, the leakage magnetic field and the electromagnetic force around phase A winding are also the largest. At 0.01s, the magnetic flux density of the leakage magnetic field is mainly concentrated in the empty channel of phase A winding. Therefore, the value at the center of the empty channel is the largest, reaching 2T.

[0113] Since the leakage magnetic flux distribution of phase A winding is the superposition of axial and radial leakage magnetic flux distributions, for ease of analysis, the leakage magnetic flux distribution of phase A winding is decomposed into axial and radial leakage magnetic flux distributions. The axial leakage magnetic flux distribution of phase A winding shows that the magnetic flux density is axially symmetrical about the height of phase A winding, accounting for the majority of the main leakage magnetic flux in the channel. The axial leakage magnetic flux at the ends of phase A winding decreases with the change of magnetic field direction, with the maximum value at the center. If the middle of the winding is taken as the origin, the direction and trend of axial leakage magnetic flux at both ends are consistent, and the magnetic flux density decreases the farther away from the middle of the winding.

[0114] The radial leakage flux distribution of phase A winding shows that the radial leakage flux of phase A winding is centrally symmetrically distributed along the center of the core column, with the magnetic flux being larger at both ends and smaller in the middle, and the radial leakage flux density at the center height being 0. Axially, with the center of phase A winding as the origin, the radial leakage flux density at the upper and lower parts is in opposite directions. The farther away from the center of phase A winding, the greater the radial leakage flux density, and it is mainly generated at the winding ends.

[0115] During transformer short-circuit operation, the A-phase winding is subjected to short-circuit electromagnetic force. The axial electromagnetic force distribution of the A-phase winding is determined by the product of the radial leakage flux distribution and the short-circuit current of the A-phase winding; the radial electromagnetic force distribution of the A-phase winding is determined by the product of the axial leakage flux distribution and the short-circuit current of the A-phase winding. The axial electromagnetic force F of the A-phase winding... z The radial electromagnetic force F of phase A winding r The method for determining the value is the same as in the above embodiments, and will not be repeated here.

[0116] During the initial short circuit, the radial magnetic induction in the middle of phase A winding is almost zero, so no axial electromagnetic force is generated in the middle. The electromagnetic force generated at the ends of phase A winding is the largest and in the opposite direction, with a maximum value of 9.55 × 10⁻⁶. 6N / m3 (Newtons per cubic meter), therefore, the A-phase winding will still experience axial instability due to the axial electromagnetic force. When the axial electromagnetic force of the A-phase winding is too large, it will cause the transformer's A-phase winding to collide and rub against the structural components, resulting in insulation damage to the conductor turns and ultimately axial instability.

[0117] During the initial short circuit, the radial electromagnetic force induced in the middle of phase A winding is the largest, reaching 2.77 × 10⁻⁶. 7 The electromagnetic forces generated at the top and bottom of the transformer are symmetrically distributed about the center height of phase A winding. When the radial electromagnetic force reaches a certain average critical value, phase A winding will experience radial instability. In severe cases, this can lead to the breakage of the turn insulation of phase A winding, causing inter-turn short circuits. Under the combined action of axial and radial electromagnetic forces, the pads will shrink and shift, and the conductors will loosen or tilt. Repeated short-circuit impacts can lead to insulation failure, ultimately causing serious transformer operation accidents.

[0118] Using the methods described above, firstly, a transformer reclosing circuit model based on reclosing is constructed, and the amplitude of the secondary short-circuit current under different short-circuit conditions is calculated. The short-circuit condition with the largest secondary short-circuit current amplitude is determined to be a three-phase short circuit. Secondly, the short-circuit currents corresponding to the three phases of the winding at different closing angles under the three-phase short-circuit condition are analyzed and calculated: when the closing angle is 0°, the maximum short-circuit current amplitude in the winding is the largest compared to other closing angles. However, when the closing angle is 90°, the maximum short-circuit current amplitude in the winding is 3379A, which is the smallest compared to other closing angles. Finally, a three-dimensional finite element simulation model of the transformer's magnetic-circuit-force system is constructed, and the leakage flux distribution and electromagnetic force distribution corresponding to the three phases of the transformer winding are calculated. The conclusion is that the electromagnetic force generated at the ends of the winding is the largest and in opposite directions.

[0119] The above-mentioned optional implementation methods achieve at least the following effects: By determining the short-circuit current of the winding under different closing angles, the problem of inaccurate determination of the electromagnetic force distribution of the transformer winding after reclosing can be effectively solved, thereby optimizing the transformer design and power system protection strategy, and significantly improving the safety and operating efficiency of the power system; by establishing and accurately solving the three-dimensional finite element simulation model of magneto-circuit-force, the electromagnetic force distribution of the three phases of the winding under different short-circuit conditions and closing angles can be quantified, improving the accuracy of the electromagnetic force distribution determination results; accurate calculation of the electromagnetic force distribution can provide a scientific basis for the structural optimization of the transformer winding, help to evaluate and enhance the mechanical strength of the winding, and prevent instability under extreme conditions.

[0120] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0121] This embodiment also provides an electromagnetic force distribution determination device for transformer windings. This device is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the terms "module" and "device" can refer to a combination of software and / or hardware that performs a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0122] According to an embodiment of this application, an apparatus embodiment for implementing a method for determining the electromagnetic force distribution of a transformer winding is also provided. Figure 8 This is a schematic diagram of an electromagnetic force distribution determination device for a transformer winding according to an embodiment of this application, as shown below. Figure 8 As shown, the electromagnetic force distribution determination device for the above-mentioned transformer winding includes a geometric parameter determination module 802, a short-circuit current determination module 804, and an electromagnetic force distribution determination module 806. The device will be described below.

[0123] The geometric parameter determination module 802 is used to determine the geometric parameters of the transformer windings;

[0124] The short-circuit current determination module 804 is connected to the geometric parameter determination module 802 and is used to determine the short-circuit current corresponding to the three phases of the winding under the target closing angle. The closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed. The short-circuit current is obtained when there is still a three-phase short circuit after the transformer is reclosed. Reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault.

[0125] The electromagnetic force distribution determination module 806 is connected to the short-circuit current determination module 804 and is used to determine the electromagnetic force distribution of the three phases of the winding at the target closing angle based on geometric parameters and the short-circuit currents corresponding to the three phases.

[0126] In the electromagnetic force distribution determination device for a transformer winding provided in this application embodiment, a geometric parameter determination module 802 is set to determine the geometric parameters of the transformer winding; a short-circuit current determination module 804, connected to the geometric parameter determination module 802, is used to determine the short-circuit current corresponding to the three phases of the winding at a target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained when a three-phase short circuit still exists after the transformer is reclosed, and reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; an electromagnetic force distribution determination module 806, connected to the short-circuit current determination module 804, is used to determine the electromagnetic force distribution corresponding to the three phases of the winding at the target closing angle based on the geometric parameters and the short-circuit current corresponding to the three phases. The goal is to determine the electromagnetic force distribution of the transformer winding based on its geometric parameters and the short-circuit current at the target closing angle under three-phase short-circuit conditions. This improves the accuracy of the determination of the electromagnetic force distribution of the transformer winding at the target closing angle after transformer reclosing, thereby solving the technical problem of inaccurate determination of the electromagnetic force distribution of the transformer winding after transformer reclosing in related technologies.

[0127] It should be noted that the above modules can be implemented by software or hardware. For example, for the latter, it can be implemented in the following ways: the above modules can be located in the same processor; or the above modules can be located in different processors in any combination.

[0128] It should be noted that the geometric parameter determination module 802, short-circuit current determination module 804, and electromagnetic force distribution determination module 806 correspond to steps S102 to S106 in the embodiments. The examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should be noted that the above modules, as part of the device, can run in a computer terminal.

[0129] It should be noted that the optional or preferred implementation methods of this embodiment can be found in the relevant descriptions in the embodiments, and will not be repeated here.

[0130] The electromagnetic force distribution determination device for the transformer winding described above may also include a processor and a memory. The geometric parameter determination module 802, the short-circuit current determination module 804, the electromagnetic force distribution determination module 806, etc., are all stored in the memory as program units. The processor executes the program units stored in the memory to realize the corresponding functions.

[0131] The processor contains a core that retrieves the corresponding program unit from memory. One or more cores may be configured. Memory may include non-persistent memory in computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory includes at least one memory chip.

[0132] This application provides a non-volatile storage medium storing a program that, when executed by a processor, implements a method for determining the electromagnetic force distribution of a transformer winding.

[0133] This application provides an electronic device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs the following steps: determining the geometric parameters of the transformer windings; determining the short-circuit currents corresponding to the three phases of the windings at a target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained under the condition that a three-phase short circuit still exists after the transformer is reclosed; reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; and determining the electromagnetic force distribution corresponding to the three phases of the windings at the target closing angle based on the geometric parameters and the corresponding short-circuit currents. The device described herein may be a server, PC, etc.

[0134] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having the following method steps: determining the geometric parameters of the transformer windings; determining the short-circuit currents corresponding to the three phases of the windings at a target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained under the condition that a three-phase short circuit still exists after the transformer is reclosed, and reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault; and determining the electromagnetic force distribution corresponding to the three phases of the windings at the target closing angle based on the geometric parameters and the corresponding short-circuit currents of the three phases.

[0135] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied 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.

[0136] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations 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, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0137] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0138] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0139] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0140] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0141] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, 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 technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0142] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0143] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied 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.

[0144] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for determining the electromagnetic force distribution of a transformer winding, characterized in that, include: Determine the geometric parameters of the transformer windings; Determine the short-circuit currents corresponding to the three phases of the winding at the target closing angle, wherein the closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed, and the short-circuit current is obtained when a three-phase short circuit still exists after the transformer is reclosed, and the reclosing refers to closing the circuit breaker of the transformer that was disconnected due to a fault. Based on the geometric parameters and the short-circuit currents corresponding to the three phases, the electromagnetic force distribution of the three phases of the winding is determined at the target closing angle.

2. The method according to claim 1, characterized in that, The determination of the short-circuit currents corresponding to the three phases of the winding at the target closing angle includes: For any one of the three phases, determine the integral constant, angular frequency, first line impedance angle, and first steady-state short-circuit current amplitude of that phase. The integral constant is determined based on the state of the series circuit in which the winding is located before the circuit breaker is closed. The angular frequency is used to describe the rate of change of any short-circuit current of any phase with time. The first line impedance angle is used to describe the ratio of resistance to reactance in the series circuit after reclosing. The first steady-state short-circuit current amplitude refers to the maximum instantaneous amplitude of the AC current in the winding when the current in the series circuit no longer changes with time after reclosing. Based on the integral constant, the angular frequency, the first line impedance angle, the first steady-state short-circuit current amplitude, and the target closing angle, determine the short-circuit current of any phase. The short-circuit currents corresponding to the three phases are determined by determining any one of the short-circuit currents.

3. The method according to claim 2, characterized in that, Determining the integral constant of any phase includes: Determine the second steady-state short-circuit current amplitude of any phase before reclosing, and the second line impedance angle of any phase before reclosing; The integral constant is determined based on the second steady-state short-circuit current amplitude and the second line impedance angle.

4. The method according to any one of claims 1 to 3, characterized in that, The determination of the electromagnetic force distribution of the three phases of the winding at the target closing angle based on the geometric parameters and the corresponding short-circuit currents of the three phases includes: For any one of the three phases, based on the geometric parameters and any short-circuit current of any one phase, determine the electromagnetic force distribution of the winding in that phase; The electromagnetic force distributions corresponding to the three phases are determined by determining the electromagnetic force distribution of any one of the phases.

5. The method according to claim 4, characterized in that, Determining the electromagnetic force distribution of the winding in any phase based on the geometric parameters and any short-circuit current in any phase includes: Based on the geometric parameters, the material information of the winding, and the short-circuit current, the leakage magnetic flux distribution of any phase is determined, wherein the leakage magnetic flux distribution is used to describe the variation law of magnetic field strength and magnetic flux density in the space surrounding the winding. Based on the geometric parameters, the any short-circuit current, and the leakage magnetic field distribution, the electromagnetic force distribution is determined.

6. The method according to claim 5, characterized in that, When the leakage magnetic field distribution includes axial and radial leakage magnetic field distributions, and the electromagnetic force distribution includes axial and radial electromagnetic force distributions, determining the electromagnetic force distribution based on the geometric parameters, the any short-circuit current, and the leakage magnetic field distribution includes: Based on the geometric parameters, the any short-circuit current, and the axial leakage magnetic field distribution, the radial electromagnetic force distribution is determined, wherein the axial leakage magnetic field distribution is used to describe the variation law of the magnetic field strength of the winding in the axial direction, and the axial direction refers to the direction of the central axis of the winding; Based on the geometric parameters, the any short-circuit current, and the radial leakage magnetic field distribution, the axial electromagnetic force distribution is determined, wherein the radial leakage magnetic field distribution is used to describe the variation law of the magnetic field strength of the winding in the radial direction, and the radial direction refers to the radial direction of the winding that is perpendicular to the axial direction.

7. A device for determining the electromagnetic force distribution of a transformer winding, characterized in that, include: The geometric parameter determination module is used to determine the geometric parameters of the transformer windings; The short-circuit current determination module is used to determine the short-circuit current corresponding to the three phases of the winding at the target closing angle. The closing angle refers to the phase angle of the power supply voltage when the circuit breaker is closed. The short-circuit current is obtained when there is still a three-phase short circuit after the transformer is reclosed. The reclosing refers to closing the circuit breaker of the transformer that was opened due to a fault. The electromagnetic force distribution determination module is used to determine the electromagnetic force distribution of the three phases of the winding at the target closing angle based on the geometric parameters and the short-circuit currents corresponding to the three phases.

8. A non-volatile storage medium, characterized in that, The non-volatile storage medium stores multiple instructions, which are adapted to be loaded by a processor and executed by the method for determining the electromagnetic force distribution of transformer windings according to any one of claims 1 to 6.

9. An electronic device, characterized in that, include: One or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the method for determining the electromagnetic force distribution of a transformer winding as described in any one of claims 1 to 6.

10. A computer program product comprising computer instructions, characterized in that, When the computer instructions are executed by the processor, they implement the steps of the method described in any one of claims 1 to 6.

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