Method, system and readable storage medium for determining magnetizing inrush current of transformer

Abstract

The present invention provides a method, system, and readable storage medium for determining a transformer's excitation inrush current. The method comprises: obtaining the air-core inductance of a transformer coil; determining a reference time t for each of a plurality of cycles of the excitation inrush current; and determining a reference time t for each of a plurality of cycles of the excitation inrush current. max , where the reference time t max The initial moment when the magnetic flux density of the transformer core is greater than the maximum magnetic flux density of the core within one cycle. max , determine the transformer's magnetizing inrush current in each cycle.

Description

Technical Field

[0001] The present application relates to the field of transformers, and in particular to a method, system, and readable storage medium for determining a transformer's excitation inrush current. Background Art

[0002] With the development of the economy, electricity has been widely used in all aspects of society due to its pollution-free characteristics. As an important electrical equipment in the power conversion system, the normal operation of the transformer is directly related to the safety of people's lives and property.

[0003] When a transformer is connected to the grid under no-load conditions, a high-amplitude magnetizing inrush current is generated due to the saturation of the transformer core's magnetic flux and the nonlinear characteristics of the core material. This inrush current not only causes the transformer's differential protection to malfunction but also poses a threat to the power system through harmonic pollution, ferroresonance, and grid voltage sag. Existing calculations of this inrush current are inaccurate and suffer from significant errors. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method, system and readable storage medium for determining the magnetizing inrush current of a transformer that can reduce the calculation error of the magnetizing inrush current.

[0005] An embodiment of the present application provides a method for determining a transformer's magnetizing inrush current, comprising:

[0006] Obtaining the air-core inductance of the coil of the transformer;

[0007] Determine the reference time t of each cycle of the multiple cycles of the excitation inrush current max , where the reference time t max is the initial moment when the magnetic flux density of the transformer core is greater than the maximum magnetic flux density of the core within one cycle; and

[0008] According to the air-core inductance and the reference time t of each cycle max , determine the excitation inrush current of the transformer in each cycle.

[0009] Optionally, the reference time t of each cycle of the multiple cycles of the excitation inrush current is determined max ,include:

[0010] Divide the duration of each cycle into N equal parts to obtain N+1 sub-times, where N is a positive integer greater than 1, and the N+1 sub-times include the start time and end time of the corresponding cycle;

[0011] Determine the earliest sub-time corresponding to the magnetic flux density of the core greater than the maximum magnetic flux density among the N+1 sub-times, which is the reference time t corresponding to the cycle max .

[0012] Optionally, the reference time t of each cycle according to the air-core inductor max , determining the magnetizing inrush current of the transformer in each cycle, including:

[0013] According to the reference time t of each cycle max and the difference between the time in each cycle, determining the exponent of the exponential function;

[0014] determining a value of an exponential function using the exponent;

[0015] The magnetizing inrush current of the transformer in each cycle is determined according to the value of the exponential function.

[0016] Optionally, the reference time t of each cycle according to the air-core inductor max , determining the magnetizing inrush current of the transformer in each cycle, including:

[0017] According to the reference time t of each cycle max and t0 to determine the value of the trigonometric function, wherein t0 is the time corresponding to the initial closing angle of the transformer; and

[0018] The magnetizing inrush current of the transformer in each cycle is determined according to the value of the trigonometric function.

[0019] Optionally, the reference time t of each cycle according to the air-core inductor max , determining the magnetizing inrush current of the transformer in each cycle, including:

[0020] The magnetizing inrush current of the transformer in each cycle is determined according to the system impedance of the transformer.

[0021] Optionally, determining the magnetizing inrush current of the transformer in each cycle according to the system impedance of the transformer includes:

[0022] The magnetizing inrush current of the transformer in each cycle is determined according to the sum of the system impedance and wL, where w is the angular frequency of the applied voltage to the coil and L is the air-core inductance of the coil.

[0023] Optionally, the reference time t of each cycle according to the air-core inductor max , determining the magnetizing inrush current of the transformer in each cycle, including:

[0024] Determine the residual magnetism attenuation of the previous cycle based on the angle corresponding to the overflow magnetic flux of the previous cycle and the residual magnetism attenuation correction coefficient;

[0025] Determine the remanence of the current cycle based on the remanence of the previous cycle and the attenuation of the remanence of the previous cycle;

[0026] According to the remanence of the current cycle and the reference time t of the current cycle max , determine the excitation inrush current of the current cycle.

[0027] Optionally, the reference time t of each cycle according to the air-core inductor max , determining the magnetizing inrush current of the transformer in each cycle, including:

[0028] According to the air-core inductor, the reference time t of each cycle max and the structural correction factor of the transformer, and determine the excitation inrush current of the transformer in each cycle.

[0029] Optionally, the reference time t of each cycle according to the air-core inductor max and the structural correction coefficient of the transformer, and determining the magnetizing inrush current of the transformer in each cycle, including:

[0030] Obtaining structural information of the transformer;

[0031] A structural correction coefficient of the transformer is determined according to the structural information.

[0032] An embodiment of the present application provides a system for determining the magnetizing inrush current of a transformer, comprising one or more processors for implementing any of the above-mentioned determination methods.

[0033] An embodiment of the present application provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, any of the above-described determination methods is implemented.

[0034] The method for determining the magnetizing inrush current of a transformer provided in an embodiment of the present application obtains the air-core inductance of the coil and determines the reference time t of each of the multiple cycles of the magnetizing inrush current. max , based on the air-core inductance and the reference time t of each cycle max , determine the excitation inrush current in each cycle. In this way, in the process of determining the excitation inrush current, the reference time t is added max Participate in the determination of the excitation inrush current and consider the initial moment when the magnetic flux density of the core is greater than the maximum magnetic flux density of the core within one cycle, so as to make the determined excitation inrush current more accurate and reduce the calculation error of the excitation inrush current. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Shown is a model diagram of the coil and air bag of an embodiment of the present application;

[0036] Figure 21 is a flow chart of a method for determining a transformer's magnetizing inrush current according to an embodiment of the present application;

[0037] Figure 3 Shown Figure 2 Flowchart for determining magnetizing inrush current based on the value of the exponential function;

[0038] Figure 4 Shown Figure 2 Flowchart for determining magnetizing inrush current based on the value of trigonometric function;

[0039] Figure 5 Shown is a flow chart for determining the structural correction coefficient of a transformer in an embodiment of the present application;

[0040] Figure 6 Shown Figure 2 Flow chart for determining the magnetizing inrush current based on the remanence of the current cycle;

[0041] Figure 7 The figure shows a module block diagram of a system for determining the magnetizing inrush current of a transformer in an embodiment of the present application. DETAILED DESCRIPTION

[0042] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of devices consistent with certain aspects of the present application, as detailed in the appended claims.

[0043] The terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit this application. Unless otherwise defined, technical or scientific terms used in this application should have the same ordinary meaning as those of ordinary skill in the art to which this invention belongs. The terms "first," "second," and similar words used in this specification and claims do not denote any order, quantity, or importance, but are simply used to distinguish one component from another. Similarly, the terms "a" or "an" and similar words do not denote a limitation of quantity, but rather denote the presence of at least one. The terms "plurality" or "several" refer to two or more. The terms "include" or "comprising" and similar words mean that the elements or articles preceding the term "include" or "comprising" include the elements or articles listed after the term and their equivalents, and do not exclude other elements or articles. The terms "connected" or "connected" and similar words are not limited to physical or mechanical connections and can also include electrical connections, whether direct or indirect. As used in this specification and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0044] An embodiment of the present application provides a method for determining a transformer's magnetizing inrush current, comprising:

[0045] Obtaining the air-core inductance of the coil of the transformer;

[0046] Determine the reference time t of each cycle of the multiple cycles of the excitation inrush current max , where the reference time t max is the initial moment when the magnetic flux density of the transformer core is greater than the maximum magnetic flux density of the core within one cycle; and

[0047] According to the air-core inductance and the reference time t of each cycle max , determine the excitation inrush current of the transformer in each cycle.

[0048] The method for determining the magnetizing inrush current of a transformer provided in an embodiment of the present application obtains the air-core inductance of the coil and determines the reference time t of each of the multiple cycles of the magnetizing inrush current. max , based on the air-core inductance and the reference time t of each cycle max , determine the excitation inrush current in each cycle. In this way, in the process of determining the excitation inrush current, the reference time t is added maxParticipate in the determination of the excitation inrush current and consider the initial moment when the magnetic flux density of the core is greater than the maximum magnetic flux density of the core within one cycle, so as to make the determined excitation inrush current more accurate and reduce the calculation error of the excitation inrush current.

[0049] See also Figure 1 As shown, an embodiment of the present application provides a method 100 for determining the magnetizing inrush current of a transformer. The method 100 for determining the magnetizing inrush current of a transformer includes steps S101 to S103.

[0050] In step S101 , the air-core inductance L of the coil of the transformer is obtained.

[0051] Please refer to Figure 2 In some embodiments, the air-core inductance L of the transformer coil can be determined by finite element magnetic field simulation. The coil model can be established in Magnet simulation software or other software according to the specifications of the transformer coil, such as the number of turns of the coil. Figure 2 The coil 102 model in Figure 1 is shown. The transformer coil is wound around the transformer core, carrying current. The core provides structural support, and the magnetic circuit is closed through the core. The core and coil work together to induce electromagnetic induction, transferring electrical energy from the low-voltage side to the high-voltage side through the magnetic circuit. Because the core's magnetic permeability is very low when saturated, it can be approximated to the permeability of air. Therefore, in actual modeling, only the coil model can be built, omitting the core model. This allows calculation of the air-core inductance of the coil under no-load conditions.

[0052] An air envelope 101 is set up in the simulation software based on the transformer's oil tank dimensions. Air envelope 101 surrounds coil 102. The coil 102 model and air envelope 101 can be rotated by a certain angle to simplify calculations and improve the simulation software's efficiency. The rotation angle can be flexibly selected based on the modeler's experience, such as 5 or 10 degrees. Boundary conditions, such as a strong vertical boundary condition, are applied to air envelope 101.

[0053] The current of the coil 102 can be set by the user, for example, 1A. The energy E of the coil 102 can be calculated using two-dimensional time harmonics. The formula L = 2*E / I 2 Determine the value of the air-core inductor L.

[0054] In some embodiments, the coil resistance of the coil 102 can be determined by the formula R=ρ*L / S, where R represents the coil resistance, ρ represents the resistivity of the coil, and S represents the cross-sectional area of ​​the wire of the coil.

[0055] In some other embodiments, the air-core inductance L may be determined by an empirical formula of the air-core inductance L.

[0056] In step S102, a reference time t of each of a plurality of cycles of the magnetizing inrush current is determined. max , where the reference time t max The initial moment when the magnetic flux density of the transformer core is greater than the maximum magnetic flux density of the core within one cycle. max , participate in the calculation of the excitation inrush current, thereby reducing the calculation error of the excitation inrush current.

[0057] The duration of each cycle is divided into N equal parts to obtain N+1 sub-moments, where N is a positive integer greater than 1, and the N+1 sub-moments include the start and end moments of the corresponding cycle. The change in the excitation inrush current from one point to another is a cycle. In some embodiments, the duration corresponding to a cycle can be the period of alternating current, such as 0.02s. The duration of each cycle can be divided into N equal parts, where N can be 80, 100, 150, etc. For example, 0.02s can be divided into 100 equal parts to obtain 101 sub-moments, where the 101 sub-moments include the 1st moment and the 101st sub-moments of this cycle.

[0058] Determine the earliest sub-time corresponding to the magnetic flux density of the core greater than the maximum magnetic flux density among the N+1 sub-times, which is the reference time t corresponding to the cycle max The maximum magnetic flux density can be expressed as B max In some embodiments, the maximum magnetic flux density can be set according to specific requirements, for example, it can be 2 Tesla. Starting from the first sub-moment, the magnetic flux density of the coil 102 corresponding to the first sub-moment is compared with the maximum magnetic flux density. If the magnetic flux density corresponding to the first sub-moment is greater than the maximum magnetic flux density, the first sub-moment is determined as the reference time t of the corresponding cycle. max If the magnetic flux density corresponding to the first sub-moment is not greater than the maximum magnetic flux density, compare the magnetic flux density corresponding to the second sub-moment with the maximum magnetic flux density, and iterate continuously until the corresponding moment greater than the maximum magnetic flux density is found, which is the reference moment t of the corresponding cycle. max .

[0059] In step S103, based on the air-core inductor and the reference time t of each cycle max , determine the transformer's magnetizing inrush current in each cycle.

[0060] Thus, in the process of determining the magnetizing inrush current, the reference time t is added. max Participate in the determination of the excitation inrush current and consider the initial moment when the magnetic flux density of the core is greater than the maximum magnetic flux density of the core within one cycle, so as to make the determined excitation inrush current more accurate and reduce the calculation error of the excitation inrush current.

[0061] Please refer to Figure 3In some embodiments, step S103 includes steps S301 to S303.

[0062] In step S301, according to the reference time t of each cycle max The difference between the time in each cycle and the time in each cycle determines the exponent of the exponential function. max The difference between the time t in each cycle, the exponent of the exponential function can be t max -t.

[0063] In step S302, the value of the exponential function is determined using the exponential. In some embodiments, the base of the exponential function can be e, and the value of the exponential function can be In other embodiments, the base of the exponential function may also be 2, 3, etc., and can be flexibly set.

[0064] In some embodiments, the determination of the value of the exponential function also includes a time constant, which can be L / R, and the value of the exponential function can be

[0065] In step S303 , the magnetizing inrush current of the transformer in each cycle is determined according to the value of the exponential function.

[0066] In the embodiment of the present application, by referring to the time t max The value of the exponential function is determined, and then the magnetizing inrush current of the transformer in each cycle is determined. In this way, the determined magnetizing inrush current is more accurate, and the calculation error of the magnetizing inrush current is reduced.

[0067] Please refer to Figure 4 In some embodiments, step S103 also includes steps S304 to S305.

[0068] In step S304, according to the reference time t of each cycle max The sum of t and t0 determines the value of the trigonometric function, where t0 is the time corresponding to the initial closing angle of the transformer. max + t0, determine the value of the trigonometric function. The trigonometric function may include sine function, cosine function and tangent function. In some embodiments, the trigonometric function may be the sine function sin, and the value of the trigonometric function may be sin(wt max +wt0), where w is the angular frequency of the voltage applied to the coil 102. In some embodiments, the value of the trigonometric function can also be obtained by sin in, is the magnetic flux of coil 102. In some embodiments, The formula can be Sure.

[0069] In some embodiments, t0 can be determined by the formula t0=α / 2πf, where α is the initial closing angle, which can be set by the user, and f is the frequency of the voltage applied to the coil 102.

[0070] In some embodiments, the closing angle for each cycle can be the same. For example, when the voltage frequency is 50 Hz, each cycle corresponds to a duration of 0.02 seconds. The magnetizing inrush current for each cycle is calculated separately. Therefore, the same closing angle can be used to determine the waveform of the magnetizing current for each cycle. The waveforms of the magnetizing inrush current for each cycle are then connected to obtain the magnetizing inrush current of the transformer for each cycle.

[0071] In step S305 , the magnetizing inrush current of the transformer in each cycle is determined according to the value of the trigonometric function.

[0072] In the embodiment of the present application, by referring to the time t max The value of the trigonometric function is determined, and then the magnetizing inrush current of the transformer in each cycle is determined. In this way, the determined magnetizing inrush current is more accurate, and the calculation error of the magnetizing inrush current is reduced.

[0073] In some embodiments, the magnetizing inrush current of the transformer in each cycle may be determined by multiplying the value of the trigonometric function by the value of the exponential function.

[0074] In some embodiments, the transformer's magnetizing inrush current in each cycle is determined based on the main trigonometric function, the trigonometric function, and the exponential function. Specifically, i(t) = (main trigonometric function - trigonometric function) * exponential function. In some embodiments, the main trigonometric function can be Where U is the effective value of the phase voltage applied to the coil 102. The transformer's magnetizing inrush current in each cycle can be expressed by the formula

[0075] Sure.

[0076] In some embodiments, the transformer's magnetizing inrush current within each cycle is determined based on the transformer's system impedance. The transformer's system impedance is represented by net. By taking the transformer's system impedance into account, the transformer's magnetizing inrush current is determined more accurately and with less error.

[0077] In some embodiments, the transformer magnetizing inrush current in each cycle is determined based on the sum of the system impedance and wL, where w and L have been introduced above and will not be repeated here.

[0078] Determine the transformer's magnetizing inrush current in each cycle. In some embodiments, the influence of the coil resistance R on the magnetizing current can also be considered. The transformer's magnetizing current in each cycle can be calculated using the formula Determine, thereby making the determined excitation current more accurate.

[0079] In some embodiments, based on the air-core inductor, the reference time t of each cycle max The transformer's magnetizing inrush current in each cycle is determined by taking into account the transformer's structural correction factor. In the transformer's magnetizing inrush current calculation, the calculated magnetizing inrush current is made to correspond to the transformer's structure, thus meeting the calculation requirements of transformers with different structures. In some embodiments, the transformer's magnetizing inrush current in each cycle can be calculated using the formula

[0080] Determine, where M is the structural correction factor of the transformer.

[0081] See Figure 5 , the structural correction coefficient M of the transformer can be determined through steps S306 to S307.

[0082] In step S306, the structure information of the transformer is obtained. The user can input the structure information of the transformer, and the structure of the transformer may include single-phase three-pole, single-phase four-pole, single-phase five-pole, three-phase three-pole, and three-phase five-pole.

[0083] In step S307, the structure correction coefficient of the transformer is determined based on the structure information. In some embodiments, the structure correction coefficient M of the transformer can be determined using the following table.

[0084]

[0085] Where YN represents the coil connection method as a star with a neutral line, Y represents a star connection, and D represents a delta connection. This allows for quick determination of the transformer's structural correction factor, improving the efficiency of magnetizing inrush current calculations.

[0086] Please refer to Figure 6 In some embodiments, step S103 also includes steps S308 to S310.

[0087] Among them, in step S308, the residual magnetism attenuation of the previous cycle is determined based on the angle corresponding to the overflow flux of the previous cycle and the residual magnetism attenuation correction coefficient. In the initial part of the transformer closing to generate the excitation surge current, the excitation surge current is mainly generated by the magnetic flux in the air outside the core. Because the magnetic permeability of the air is small, the excitation surge current is large, much larger than the excitation current when the working flux is less than the saturation flux. Therefore, the waveform of the excitation surge current only appears in a section of the sine wave with the overflow flux, that is, the angle corresponding to the overflow flux, which can be expressed by θ. In the section from -θ to +θ, the excitation surge current is generated, and i(t) is not 0. The residual magnetism attenuation can be expressed by ΔBr express.

[0088] In some embodiments, the angle corresponding to the overflow flux can be expressed as

[0089] Determine; where Bmax represents the maximum magnetic flux density; B represents the working magnetic flux density, B r It indicates the residual magnetism of the previous cycle. It should be noted that the formula can be transformed into or

[0090] In some embodiments, the residual magnetism of the previous cycle decays ΔB r The formula ΔB r =A*B*R*2*(sinθ-θ*cosθ) / wL, where A is the residual magnetization attenuation coefficient. In some embodiments, the residual magnetization attenuation coefficient A can be obtained based on actual engineering practice, such as 1.5, 2, etc.

[0091] In step S309, the remanence of the current cycle is determined based on the remanence of the previous cycle and the attenuation of the remanence of the previous cycle. r Subtract the residual magnetism attenuation ΔB of the previous cycle r , determine the remanence B of the current cycle r The remanence of the current cycle B r Formula B r =B r -ΔB r The first B is the remanence B of the current cycle. r , the second B r is the remanence B of the previous cycle r In this way, the remanence B of the current cycle can be calculated. r It should be noted that the remanence B of the first cycle r It can be set by the user. When the residual magnetism B gradually decays to 0, there is no more magnetic flux overflowing into the air outside the core, and the excitation inrush current disappears.

[0092] In step S310, according to the remanence of the current cycle and the reference time t max , determine the current cycle of the excitation inrush current. The current cycle of the residual magnetism B r Will affect the reference time t of the current cycle max Determination of the current cycle remanence B r It will affect the initial moment when the magnetic flux density of the core in the current cycle is greater than the maximum magnetic flux density of the core, and the remanence B of the current cycle r Different, determine the reference time t of the current cycle max Determine the reference time t of the current cycle maxThe method has been described above. What needs to be explained is that the remanence B of the current frequency r It will also affect the peak value of the excitation inrush current of the current cycle.

[0093] In the embodiment of the present application, the residual magnetism of the current cycle is obtained by calculating the residual magnetism attenuation of the previous cycle, and then the excitation inrush current of the current cycle is calculated. In this way, the excitation inrush current of each cycle can be calculated, and then the total excitation inrush current of the transformer can be obtained.

[0094] Figure 7 The figure shows a block diagram of one embodiment of a system 800 for determining transformer magnetizing inrush current. The system 800 includes one or more processors 801 for implementing the optimization method. In some embodiments, the system 800 may include a computer-readable storage medium 804, which may store a program callable by the processor 801 and may include a non-volatile storage medium. In some embodiments, the system 800 may include a memory 803 and an interface 802. In some embodiments, the system 800 may also include other hardware depending on the actual application.

[0095] The computer-readable storage medium 804 of the embodiment of the present application stores a program thereon, and when the program is executed by the processor, the control method is implemented.

[0096] The present application may take the form of a computer program product implemented on one or more storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing program code. Computer-readable storage media include permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, modules of programs or other data. Examples of computer-readable 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, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

[0097] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for determining the magnetizing inrush current of a transformer, characterized in that: include: Obtaining the air-core inductance of the coil of the transformer; Determine the reference time t of each cycle of the multiple cycles of the excitation inrush current max , where the reference time t max is the initial moment when the magnetic flux density of the transformer core is greater than the maximum magnetic flux density of the core within one cycle; and According to the air-core inductance and the reference time t of each cycle max , determining the magnetizing inrush current of the transformer in each cycle; The reference time t of each cycle of the multiple cycles of the excitation inrush current is determined max ,include: Divide the duration of each cycle into N equal parts to obtain N+1 sub-times, where N is a positive integer greater than 1, and the N+1 sub-times include the start time and end time of the corresponding cycle; Determine the earliest sub-time corresponding to the magnetic flux density of the core greater than the maximum magnetic flux density among the N+1 sub-times, which is the reference time t corresponding to the cycle max .

2. The method for determining the magnetizing inrush current of a transformer according to claim 1, wherein: The reference time t of each cycle according to the air-core inductance max , determining the magnetizing inrush current of the transformer in each cycle, including: According to the reference time t of each cycle max and the difference between the time in each cycle, determining the exponent of the exponential function; determining a value of an exponential function using the exponent; The magnetizing inrush current of the transformer in each cycle is determined according to the value of the exponential function.

3. The method for determining the magnetizing inrush current of a transformer according to claim 1 or 2, characterized in that: The reference time t of each cycle according to the air-core inductance max , determining the magnetizing inrush current of the transformer in each cycle, including: According to the reference time t of each cycle max and t0 to determine the value of the trigonometric function, wherein t0 is the time corresponding to the initial closing angle of the transformer; and The magnetizing inrush current of the transformer in each cycle is determined according to the value of the trigonometric function.

4. The method for determining the magnetizing inrush current of a transformer according to claim 1, wherein: The reference time t of each cycle according to the air-core inductance max , determining the magnetizing inrush current of the transformer in each cycle, including: The magnetizing inrush current of the transformer in each cycle is determined according to the system impedance of the transformer.

5. The method for determining the magnetizing inrush current of a transformer according to claim 4, wherein: The step of determining the magnetizing inrush current of the transformer in each cycle according to the system impedance of the transformer includes: The magnetizing inrush current of the transformer in each cycle is determined according to the sum of the system impedance and wL, where w is the angular frequency of the applied voltage to the coil and L is the air-core inductance of the coil.

6. The method for determining the magnetizing inrush current of a transformer according to claim 1, wherein: The reference time t of each cycle according to the air-core inductance max , determining the magnetizing inrush current of the transformer in each cycle, including: Determine the residual magnetism attenuation of the previous cycle based on the angle corresponding to the overflow magnetic flux of the previous cycle and the residual magnetism attenuation correction coefficient; Determine the remanence of the current cycle based on the remanence of the previous cycle and the attenuation of the remanence of the previous cycle; According to the remanence of the current cycle and the reference time t of the current cycle max , determine the excitation inrush current of the current cycle.

7. The method for determining the magnetizing inrush current of a transformer according to claim 1, wherein: The reference time t of each cycle according to the air-core inductance max , determining the magnetizing inrush current of the transformer in each cycle, including: According to the air-core inductor, the reference time t of each cycle max and the structural correction factor of the transformer, and determine the excitation inrush current of the transformer in each cycle.

8. The method for determining the magnetizing inrush current of a transformer according to claim 7, characterized in that: The reference time t of each cycle according to the air-core inductor max and the structural correction coefficient of the transformer, and determining the magnetizing inrush current of the transformer in each cycle, including: Obtaining structural information of the transformer; A structural correction coefficient of the transformer is determined according to the structural information.

9. A system for determining magnetizing inrush current of a transformer, characterized in that: The method comprises one or more processors, configured to implement the determination method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that A program is stored thereon, and when the program is executed by a processor, the determination method according to any one of claims 1 to 8 is implemented.

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