Transformer reclosing short-circuit current impulse coefficient correction method and system

Abstract

The invention discloses a transformer reclosing short-circuit current impact coefficient correction method and system, and the method comprises the steps: collecting transformer data, a topological structure and line data, and building a short-circuit current calculation model; correcting the short-circuit current calculation model according to the transformer fatigue effect parameter, performing reclosing time setting calculation on the short-circuit current calculation model, and calculating a short-circuit impact current and a short-circuit impact coefficient; and correcting the short-circuit impact coefficient by using a particle swarm algorithm, and correcting the short-circuit impact current according to the corrected short-circuit impact coefficient. According to the method, two short-circuit current calculation models are established according to whether the hysteresis loop data of the iron core is imported into the transformer model or not, and the short-circuit current calculation models are corrected according to the fatigue effect parameters of the transformer, so that the models better conform to the actual operation condition, and the calculation precision is improved. And correcting the short-circuit impact coefficient by using a particle swarm algorithm, optimizing the short-circuit impact coefficient, and further accurately correcting the short-circuit impact current.

Description

Technical Field

[0001] The invention relates to the technical field of power transformer short-circuit current calculation, and in particular to a transformer reclosing short-circuit current impact coefficient correction method and system. Background Art

[0002] Short-circuit current calculation is of great significance to the design and planning of power systems and the design and manufacture of electrical equipment. The manufacture of electrical equipment (such as transformers, circuit breakers, mutual inductors, etc.) must be based on its calculation results, and the design and setting of power system relay protection are also based on its calculation results, especially the short-circuit impulse current, whose value determines the stability characteristics of many power equipment, such as the short-circuit strength verification of transformers. Therefore, it is very important to obtain accurate short-circuit impulse current calculation results.

[0003] However, current short-circuit current calculations mainly focus on line measurement, and the transformer equipment is considered as a voltage source. The amplitude of the short-circuit current periodic component is calculated mainly by determining the line parameters, and then the short-circuit current is obtained by multiplying it by a short-circuit current impact coefficient.

[0004] The defect of this calculation method is that it only considers the parameters of the line, and only considers the transformer as a constant potential source. In fact, the transformer will show nonlinear characteristics after the core is magnetically saturated. Therefore, when there is residual magnetism, such as when the power is off and then overlapped with a permanent fault, it may cause the short-circuit current to be distorted, resulting in changes in the short-circuit impulse current. The traditional short-circuit current calculation method considering residual magnetism is mainly calculated by establishing a numerical calculation model or a finite element calculation model. The modeling time is long, which is not conducive to large-scale setting calculation.

[0005] A method for correcting the short-circuit current impulse coefficient of transformer reclosing taking into account the residual magnetism of the core is proposed. By establishing a short-circuit current calculation model taking into account the hysteresis characteristics of the transformer, the short-circuit current impulse coefficient is calculated and compared with the short-circuit current impulse coefficient calculated by the short-circuit current calculation model not taking into account the hysteresis characteristics of the transformer, and a correction value of the empirical short-circuit current impulse coefficient is obtained. Thereafter, the corrected short-circuit impulse current can be used for various checks and calculations of the power system. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is that the traditional method performs calculation by establishing a numerical calculation model or a finite element calculation model, which takes a long time to build a model and is not conducive to large-scale setting calculation.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: a method for correcting the short-circuit current impact coefficient of transformer reclosing, comprising: collecting transformer data, topological structure and line data, and establishing a short-circuit current calculation model; correcting the short-circuit current calculation model according to transformer fatigue effect parameters, performing reclosing time setting calculation on the short-circuit current calculation model, and calculating the short-circuit impact current and the short-circuit impact coefficient; correcting the short-circuit impact coefficient by using a particle swarm algorithm, and correcting the short-circuit impact current according to the corrected short-circuit impact coefficient.

[0009] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method described in the present invention, the short-circuit current calculation model includes establishing a Simulink short-circuit current calculation model of a power system containing a transformer based on the collected transformer data, topology structure and line data; depending on whether the core hysteresis loop data is imported into the transformer model, the short-circuit current calculation model is divided into a short-circuit current calculation model that takes into account the transformer hysteresis characteristics and a short-circuit current calculation model that does not take into account the transformer hysteresis characteristics.

[0010] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method described in the present invention, the transformer fatigue effect parameter includes obtaining the fatigue effect parameter from the long-term operation data and experimental data of the transformer, and establishing a mathematical model of the transformer fatigue effect, which is expressed as:

[0011] β=β0(ΔT) n

[0012]

[0013] α=α0e -λT

[0014] Where β represents the thermal fatigue coefficient; β0 represents the initial thermal fatigue coefficient; ΔT represents the temperature change amplitude; n represents the thermal fatigue index; σ f Represents fatigue strength; σ0 represents initial fatigue strength; N represents number of cycles; N0 represents reference number of cycles; b represents fatigue strength coefficient of material; α represents aging coefficient; α0 represents initial aging coefficient; λ represents aging rate constant; T represents running time; In the short-circuit current calculation model, add thermal fatigue effect, fatigue strength and aging effect modules, link to the input and output ports of the transformer, calculate the thermal fatigue coefficient, fatigue strength and aging coefficient of the transformer under different temperatures, number of cycles and running time conditions, and feed back to the short-circuit current calculation model to correct the short-circuit current calculation model.

[0015] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method described in the present invention, wherein: calculating the short-circuit impact current and the short-circuit impact coefficient includes calculating the short-circuit impact current I without taking into account the residual magnetism nh (t), expressed as:

[0016]

[0017] Where V represents the power supply voltage; Z nh Represents the total impedance of the system without considering residual magnetism; τ nh represents the time constant; t represents the time elapsed from the occurrence of the short-circuit event; the short-circuit impulse current I is calculated taking into account the residual magnetism h (t), expressed as:

[0018]

[0019] Among them, Z h Represents the total impedance of the system taking into account residual magnetism; τ h Represents the time constant; I r Represents the residual current; calculates the periodic component I of the short-circuit current m (t), expressed as:

[0020] I m (t) = I p ·sin(ωt+φ)

[0021] Among them, I p represents the amplitude of the periodic component; ω represents the angular frequency; φ represents the phase angle.

[0022] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method of the present invention, wherein: calculating the short-circuit impact current and the short-circuit impact coefficient also includes calculating the short-circuit impact coefficient k without taking into account the hysteresis characteristic nh , expressed as:

[0023]

[0024] Calculation of short-circuit impulse coefficient k taking into account hysteresis characteristics h , expressed as:

[0025]

[0026] Among them, I nh Indicates the short-circuit impulse current without considering residual magnetism; I pnh Indicates the amplitude of the short-circuit current periodic component without considering the hysteresis characteristic; I h Indicates the short-circuit impulse current taking into account residual magnetism; I ph Indicates the amplitude of the periodic component of the short-circuit current taking into account the hysteresis characteristics.

[0027] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method of the present invention, the particle swarm algorithm includes initialization with the goal of minimizing the error of the short-circuit impact coefficient, and each initial particle contains different short-circuit impact coefficient empirical values ​​k exp , randomly assign the initial velocity of each particle, set different load factors L to simulate the impact of transformers under different load conditions, and the initialization range is 1≤k exe ≤2, 0≤L≤1; for each particle, according to the short-circuit current calculation model taking into account the hysteresis characteristics of the transformer and the short-circuit current calculation model not taking into account the hysteresis characteristics of the transformer, combined with the load factor L, the short-circuit impact current and the short-circuit impact coefficient are calculated to evaluate the fitness F of each particle, which is expressed as:

[0028]

[0029] Among them, k h (L) represents the short-circuit impact coefficient taking into account the hysteresis characteristics calculated under the load factor L; k exp (L) represents the empirical value of the short-circuit impact coefficient under the load factor L; according to the historical optimal position of the particle and the global optimal position of the population, the speed and position of the particle are updated, the fitness of the new population is evaluated, and the fitness value of each particle is updated. When the maximum number of iterations is reached or the fitness value converges to the preset threshold, the iteration is stopped, and the solution with the highest fitness is used as the corrected empirical value k of the short-circuit impact coefficient nexp Output.

[0030] As a preferred solution of the transformer reclosing short-circuit current impact coefficient correction method of the present invention, wherein: the correction of the short-circuit impact current includes: according to the corrected short-circuit impact coefficient empirical value k nexp Calculate the corrected short-circuit impact coefficient K cor , expressed as:

[0031]

[0032] The corrected short-circuit impact coefficient K cor Substitute it into the product with the periodic component of the short-circuit current to obtain the short-circuit impulse current.

[0033] In the second aspect, the present invention also provides a transformer reclosing short-circuit current impact coefficient correction system, including: a model building module, which collects transformer data, topological structure and line data, and establishes a short-circuit current calculation model that takes into account the transformer hysteresis characteristics and a short-circuit current calculation model that does not take into account the transformer hysteresis characteristics according to whether the core hysteresis loop data is imported into the transformer model; a calculation module, which adds thermal fatigue effect, fatigue strength and aging effect modules to the short-circuit current calculation model, corrects the short-circuit current calculation model, performs reclosing time setting calculation on the short-circuit current calculation model, and calculates the short-circuit impact current and the short-circuit impact coefficient; a correction module, which uses a particle swarm algorithm to correct the short-circuit impact coefficient, obtains an empirical value of the corrected short-circuit impact coefficient, calculates the corrected short-circuit impact coefficient, and corrects the short-circuit impact current according to the corrected short-circuit impact coefficient.

[0034] In a third aspect, the present invention further provides a computing device, comprising: a memory and a processor;

[0035] The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the method for correcting the short-circuit current impact coefficient of the transformer reclosing switch are implemented.

[0036] In a fourth aspect, the present invention further provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for correcting the short-circuit current impact coefficient of the transformer reclosing device.

[0037] Beneficial effects of the present invention: The method of the present invention establishes two short-circuit current calculation models according to whether the core hysteresis loop data is imported into the transformer model, and corrects the short-circuit current calculation model according to the transformer fatigue effect parameter, so that the model is more in line with the actual operation situation and the calculation accuracy is improved. The particle swarm algorithm is used to correct the short-circuit impact coefficient, optimize the short-circuit impact coefficient, make it more realistically reflect the actual situation, and then accurately correct the short-circuit impact current. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0039] Figure 1 An overall flow chart of a method for correcting a short-circuit current impact coefficient of a transformer reclosing switch provided by an embodiment of the present invention;

[0040] Figure 2A schematic diagram of a short-circuit reclosing current calculation model for a transformer reclosing short-circuit current impact coefficient correction method provided by a second embodiment of the present invention;

[0041] Figure 3 A hysteresis loop setting diagram of a transformer reclosing short-circuit current impact coefficient correction method provided by the second embodiment of the present invention;

[0042] Figure 4 A low-voltage side short-circuit current diagram of a transformer reclosing short-circuit current impact coefficient correction method provided by the second embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0044] Example 1

[0045] Reference Figure 1 , as an embodiment of the present invention, provides a method for correcting a transformer reclosing short-circuit current impact coefficient, comprising:

[0046] S1: Collect transformer data, topology structure and line data, and establish a short-circuit current calculation model.

[0047] Furthermore, a Simulink short-circuit current calculation model of the power system containing the transformer is established based on the collected transformer data, topology structure and line data; the transformer data are the basic parameters of the transformer, such as rated power, rated voltage, impedance, leakage reactance, copper loss, iron loss, magnetizing current, excitation resistance, etc.

[0048] Line data refers to the parameters of power lines, such as line resistance (R), reactance (X), conductance (G), susceptance (B), etc.

[0049] The topology is the topological structure of the power system, including transformer locations, node connection methods, load and generator locations, etc.

[0050] Open MATLAB and start Simulink, add transformer, power line model and topology, and set the location of the short-circuit fault point and the short-circuit type and time.

[0051] According to whether the core hysteresis loop data is imported into the transformer model, the short-circuit current calculation model is divided into a short-circuit current calculation model taking into account the transformer hysteresis characteristics and a short-circuit current calculation model not taking into account the transformer hysteresis characteristics.

[0052] S2: Modify the short-circuit current calculation model according to the transformer fatigue effect parameters, perform reclosing time setting calculation on the short-circuit current calculation model, and calculate the short-circuit impact current and short-circuit impact coefficient.

[0053] Furthermore, factors such as aging of materials and structures, temperature changes, and changes in hysteresis characteristics of the transformer after long-term operation are considered, and the influence of fatigue effects of transformer materials and structures on their hysteresis characteristics and current conduction characteristics after long-term operation is simulated.

[0054] There are three fatigue parameters that have a greater impact on short-circuit current: fatigue strength, aging coefficient and thermal fatigue coefficient. Fatigue strength indicates the maximum stress that a material can withstand under cyclic loads and is an important indicator for measuring a material's ability to resist fatigue damage. The aging coefficient indicates the degree to which material properties gradually decay over time and reflects the performance degradation of the transformer due to aging during long-term operation. The thermal fatigue coefficient indicates the material's ability to resist fatigue damage under stress caused by temperature changes and is an important factor affecting the fatigue life of the transformer under a temperature cycle environment.

[0055] Based on these three fatigue parameters, a relatively simplified but effective fatigue strength model is established to reflect the performance changes of the transformer due to fatigue, aging and temperature cycling during long-term operation. The influence of the three fatigue parameters is directly added to the established Simulink short-circuit current calculation model of the power system containing the transformer. The mathematical model of the transformer fatigue effect is expressed as follows:

[0056] β=β0(ΔT) n

[0057]

[0058] α=α0e -λT

[0059] Where β represents the thermal fatigue coefficient; β0 represents the initial thermal fatigue coefficient; ΔT represents the temperature change amplitude; n represents the thermal fatigue index; σ f represents fatigue strength; σ0 represents initial fatigue strength; N represents the number of cycles; N0 represents the reference number of cycles; b represents the fatigue strength coefficient of the material; α represents the aging coefficient; α0 represents the initial aging coefficient; λ represents the aging rate constant; T represents the operating time.

[0060] In the short-circuit current calculation model, thermal fatigue effect, fatigue strength and aging effect modules are added and linked to the input and output ports of the transformer. The thermal fatigue coefficient, fatigue strength and aging coefficient of the transformer under different temperatures, number of cycles and operating time conditions are calculated, and the results are fed back to the short-circuit current calculation model to correct the short-circuit current calculation model.

[0061] It should be noted that if the fatigue effect of the transformer is not taken into account and it is assumed that the transformer operates under optimal conditions, the calculated short-circuit impulse current and impulse coefficient may be too high and fail to accurately reflect the short-circuit characteristics under actual operating conditions.

[0062] By correcting the hysteresis characteristics and current conduction characteristics through fatigue effect parameters, the calculated short-circuit impulse current and impulse coefficient are closer to the actual operating state, reflecting the short-circuit characteristics of the transformer under aging, thermal fatigue and stress concentration.

[0063] Furthermore, the model is calculated to set the reclosing time. The set reclosing time is the time interval for the system to automatically reclose after a short circuit occurs. This is an operating parameter used to determine the time point when the power system is reconnected after a short circuit fault. The reclosing time is usually a fixed value.

[0064] Calculating the short-circuit impulse current and the short-circuit impulse coefficient includes calculating the short-circuit impulse current I without taking into account the residual magnetism. nh (t), expressed as:

[0065]

[0066] Where V represents the power supply voltage; Z nh Represents the total impedance of the system without considering residual magnetism; τ nh represents the time constant; t represents the time elapsed from the occurrence of the short circuit event;

[0067] Calculation of short-circuit impulse current I taking into account residual magnetism h (t), expressed as:

[0068]

[0069] Among them, Z h Represents the total impedance of the system taking into account residual magnetism; τ h Represents the time constant; I r Indicates residual magnetic current;

[0070] Calculate the periodic component of the short-circuit current I m (t), expressed as:

[0071] I m (t) = I p ·sin(ωt+φ)

[0072] Among them, I p represents the amplitude of the periodic component; ω represents the angular frequency; φ represents the phase angle.

[0073] The calculation of short-circuit impulse current and short-circuit impulse coefficient also includes the calculation of the short-circuit impulse coefficient k without taking into account the hysteresis characteristics. nh , expressed as:

[0074]

[0075] Calculation of short-circuit impulse coefficient k taking into account hysteresis characteristics h , expressed as:

[0076]

[0077] Among them, I nh Indicates the short-circuit impulse current without considering residual magnetism; I pnh Indicates the amplitude of the short-circuit current periodic component without considering the hysteresis characteristic; I h Indicates the short-circuit impulse current taking into account residual magnetism; I ph Indicates the amplitude of the periodic component of the short-circuit current taking into account the hysteresis characteristics.

[0078] S3: The short-circuit impact coefficient is corrected by using a particle swarm algorithm, and the short-circuit impact current is corrected according to the corrected short-circuit impact coefficient.

[0079] Furthermore, the particle swarm algorithm is used to initialize the particles with the goal of minimizing the error of the short-circuit impact coefficient. Each initial particle contains a different empirical value k of the short-circuit impact coefficient. exp , randomly assign the initial velocity of each particle, set different load factors L to simulate the impact of transformers under different load conditions, and the initialization range is 1≤k exe ≤2,0≤L≤1.

[0080] It should be noted that the empirical value of the initial impact coefficient k exp The setting of can determine a smaller initial range based on existing experience to accelerate convergence. Generally, when the short circuit occurs on the generator voltage bus, take k exp is about 1.9. When the short circuit occurs on the high voltage side busbar of the power plant, take k exp It is about 1.85.

[0081] For each particle, the short-circuit current calculation model taking into account the hysteresis characteristics of the transformer and the short-circuit current calculation model not taking into account the hysteresis characteristics of the transformer are combined with the load factor L to calculate the short-circuit impact current and short-circuit impact coefficient, and evaluate the fitness F of each particle, which is expressed as:

[0082]

[0083] Among them, k h (L) represents the short-circuit impact coefficient taking into account the hysteresis characteristics calculated under the load factor L; k exp (L) represents the empirical value of the short-circuit impact coefficient under load factor L.

[0084] According to the historical optimal position of the particle and the global optimal position of the group, the speed and position of the particle are updated, the fitness of the new population is evaluated, and the fitness value of each particle is updated. When the maximum number of iterations is reached or the fitness value converges to the preset threshold, the iteration is stopped and the solution with the highest fitness is used as the corrected empirical value k of the short-circuit impact coefficient. nexp Output.

[0085] It should be noted that the difference in short-circuit impact current of the transformer under different load conditions is taken into account during initialization. exp and particle speed, for example, when L>80%, the initial k exp >1.8, and reduce the particle speed during the optimization process to avoid converging to the local optimal solution too quickly.

[0086] Furthermore, according to the corrected empirical value of the short-circuit impact coefficient k nexp Calculate the corrected short-circuit impact coefficient K cor , expressed as:

[0087]

[0088] The corrected short-circuit impact coefficient K cor Substitute it into the product with the periodic component of the short-circuit current to obtain the short-circuit impulse current.

[0089] The present embodiment also provides a transformer reclosing short-circuit current impact coefficient correction system, including: a model building module, which collects transformer data, topological structure and line data, and establishes a short-circuit current calculation model that takes into account the transformer hysteresis characteristics and a short-circuit current calculation model that does not take into account the transformer hysteresis characteristics according to whether the core hysteresis loop data is imported into the transformer model; a calculation module, which adds thermal fatigue effect, fatigue strength and aging effect modules to the short-circuit current calculation model, corrects the short-circuit current calculation model, performs reclosing time setting calculation on the short-circuit current calculation model, and calculates the short-circuit impact current and the short-circuit impact coefficient; a correction module, which uses a particle swarm algorithm to correct the short-circuit impact coefficient, obtains an empirical value of the corrected short-circuit impact coefficient, calculates the corrected short-circuit impact coefficient, and corrects the short-circuit impact current according to the corrected short-circuit impact coefficient.

[0090] This embodiment also provides a computing device, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the method for correcting the short-circuit current impact coefficient of transformer reclosing as proposed in the above embodiment.

[0091] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for correcting the short-circuit current impact coefficient of the transformer reclosing switch proposed in the above embodiment is implemented.

[0092] The storage medium proposed in this embodiment and the transformer reclosing short-circuit current impact coefficient correction method proposed in the above embodiment belong to the same inventive concept. The technical details not described in detail in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0093] Through the above description of the implementation method, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ReadOnly, Memory, ROM), random access memory (RandomAccessMemory, RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform the methods of various embodiments of the present invention.

[0094] Example 2

[0095] Reference Figure 2-4 , which is an embodiment of the present invention, provides a method for correcting the short-circuit current impact coefficient of a transformer reclosing switch. In order to verify the beneficial effects of the present invention, a scientific demonstration is carried out through simulation experiments.

[0096] According to the actual transformer parameters, line topology and line parameters, a Simulink short-circuit current calculation model of the power system containing the transformer is established; the present invention uses a transformer with a capacity of 40MVA and a transformation ratio of 110KV / 35KV / 10KV as an example to establish Figure 2 The short-circuit reclosing current calculation model is shown.

[0097] A, B, and C represent the three-phase lines in a three-phase power system, and N represents the neutral line or ground.

[0098] Yn and D represent the connection method of transformer windings. Yn represents star connection with neutral point grounding (Y represents star, n represents neutral point grounding), and D represents triangle connection.

[0099] S_VOL and S_V represent voltage signals, and PHI and Flux represent parameters related to magnetic flux.

[0100] LC, MC and HC represent different current or load levels, namely low current, medium current and high current.

[0101] According to whether the core hysteresis loop data is imported into the transformer model, the above model is divided into a short-circuit current calculation model taking into account the transformer hysteresis characteristics and a short-circuit current calculation model not taking into account the transformer hysteresis characteristics; the hysteresis loop parameters need to be obtained from experiments, and the hysteresis loop parameters can be input through the hysteresis design module of Simulink, and the required parameters and characteristic curves are input as follows: Figure 3 shown.

[0102] The reclosing time setting calculation is performed on the model, and the short-circuit impulse current without considering residual magnetism, the short-circuit impulse current with considering residual magnetism and the short-circuit current periodic component are calculated, and the corresponding short-circuit impulse coefficient k considering hysteresis characteristics is obtained. h The short-circuit impact coefficient k without considering the hysteresis characteristic nh The short-circuit current on the low-voltage side calculated by the case adopted in the present invention is as follows: Figure 4 As shown, it can be seen that the short-circuit current periodic component is calculated to be 14000A, and the corresponding short-circuit impact coefficient k considering the hysteresis characteristic is calculated h =1.66 and the short-circuit impact coefficient k without considering the hysteresis characteristic nh =1.69.

[0103] Coefficient k h and k nh Compare and use the difference to correct the empirical value k of the short-circuit impact coefficient exp , and obtain the corrected short-circuit impact coefficient K cor =k exp *(1.69 / 1.66);

[0104] The corrected short-circuit impact coefficient K cor By substituting it into the product with the periodic component of the short-circuit current, we can get the short-circuit impulse current.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for correcting the short-circuit current impact coefficient of transformer reclosing, characterized in that: include: Collect transformer data, topology structure and line data to establish a short-circuit current calculation model; According to the fatigue effect parameters of the transformer, the short-circuit current calculation model is modified, the reclosing time setting calculation is performed on the short-circuit current calculation model, and the short-circuit impact current and short-circuit impact coefficient are calculated; The particle swarm algorithm is used to correct the short-circuit impact coefficient, and the short-circuit impact current is corrected according to the corrected short-circuit impact coefficient.

2. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 1, characterized in that: The short-circuit current calculation model includes establishing a Simulink short-circuit current calculation model of a power system including a transformer according to the collected transformer data, topology structure and line data; According to whether the core hysteresis loop data is imported into the transformer model, the short-circuit current calculation model is divided into a short-circuit current calculation model taking into account the transformer hysteresis characteristics and a short-circuit current calculation model not taking into account the transformer hysteresis characteristics.

3. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 2, characterized in that: The transformer fatigue effect parameters include obtaining fatigue effect parameters from the long-term operation data and experimental data of the transformer, and establishing a mathematical model of the transformer fatigue effect, which is expressed as: β=β0(ΔT) n α＝α0e -λT Where β represents the thermal fatigue coefficient; β0 represents the initial thermal fatigue coefficient; ΔT represents the temperature change amplitude; n represents the thermal fatigue index; σ f represents fatigue strength; σ0 represents initial fatigue strength; N represents the number of cycles; N0 represents the number of reference cycles; b represents the fatigue strength coefficient of the material; α represents the aging coefficient; α0 represents the initial aging coefficient; λ represents the aging rate constant; T represents the operating time; In the short-circuit current calculation model, thermal fatigue effect, fatigue strength and aging effect modules are added and linked to the input and output ports of the transformer. The thermal fatigue coefficient, fatigue strength and aging coefficient of the transformer under different temperatures, number of cycles and operating time conditions are calculated, and the results are fed back to the short-circuit current calculation model to correct the short-circuit current calculation model.

4. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 3, characterized in that: Calculating the short-circuit impulse current and the short-circuit impulse coefficient includes calculating the short-circuit impulse current I without taking into account the residual magnetism. nh (t), expressed as: Where V represents the power supply voltage; Z nh Represents the total impedance of the system without considering residual magnetism; τ nh represents the time constant; t represents the time elapsed from the occurrence of the short circuit event; Calculation of short-circuit impulse current I taking into account residual magnetism h (t), expressed as: Among them, Z h Represents the total impedance of the system taking into account residual magnetism; τ h Represents the time constant; I r Indicates residual magnetic current; Calculate the periodic component I of the short-circuit current m (t), expressed as: I m (t)=I p ·sin(ωt+φ) Among them, I p represents the amplitude of the periodic component; ω represents the angular frequency; φ represents the phase angle.

5. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 4, characterized in that: Calculating the short-circuit impulse current and the short-circuit impulse coefficient also includes calculating the short-circuit impulse coefficient k without taking into account the hysteresis characteristic. nh , expressed as: Calculation of the short-circuit impulse factor k taking into account the hysteresis characteristics h , expressed as: Among them, I nh Indicates the short-circuit impulse current without considering residual magnetism; I pnh Indicates the amplitude of the short-circuit current periodic component without considering the hysteresis characteristic; I h Indicates the short-circuit impulse current taking into account residual magnetism; I ph Indicates the amplitude of the periodic component of the short-circuit current taking into account the hysteresis characteristics.

6. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 5, characterized in that: The particle swarm algorithm includes initialization with the goal of minimizing the error of the short-circuit impact coefficient, and each initial particle contains a different short-circuit impact coefficient empirical value k exp , randomly assign the initial velocity of each particle, set different load factors L to simulate the impact of transformers under different load conditions, and the initialization range is 1≤k exe ≤2,0≤L≤1; For each particle, the short-circuit current calculation model taking into account the hysteresis characteristics of the transformer and the short-circuit current calculation model not taking into account the hysteresis characteristics of the transformer are combined with the load factor L to calculate the short-circuit impact current and short-circuit impact coefficient, and evaluate the fitness F of each particle, which is expressed as: Among them, k h (L) represents the short-circuit impact coefficient taking into account the hysteresis characteristics calculated under the load factor L; k exp (L) represents the empirical value of the short-circuit impact coefficient under load factor L; According to the historical optimal position of the particle and the global optimal position of the group, the speed and position of the particle are updated, the fitness of the new population is evaluated, and the fitness value of each particle is updated. When the maximum number of iterations is reached or the fitness value converges to the preset threshold, the iteration is stopped and the solution with the highest fitness is used as the corrected empirical value k of the short-circuit impact coefficient. nexp Output.

7. The method for correcting the short-circuit current impact coefficient of transformer reclosing as claimed in claim 6, characterized in that: The modified short-circuit impulse current includes: nexp Calculate the corrected short-circuit impact coefficient K cor , expressed as: The corrected short-circuit impact coefficient K cor Substitute it into the product with the periodic component of the short-circuit current to obtain the short-circuit impulse current.

8. A transformer reclosing short-circuit current impact coefficient correction system using the method according to any one of claims 1 to 7, characterized in that: include, The model building module collects transformer data, topology structure and line data, and establishes a short-circuit current calculation model that takes into account the transformer hysteresis characteristics and a short-circuit current calculation model that does not take into account the transformer hysteresis characteristics according to whether the core hysteresis loop data is imported into the transformer model; A calculation module, in the short-circuit current calculation model, adds thermal fatigue effect, fatigue strength and aging effect modules, modifies the short-circuit current calculation model, performs reclosing time setting calculation on the short-circuit current calculation model, and calculates the short-circuit impact current and the short-circuit impact coefficient; The correction module uses a particle swarm algorithm to correct the short-circuit impact coefficient, obtains an empirical value of the corrected short-circuit impact coefficient, calculates the corrected short-circuit impact coefficient, and corrects the short-circuit impact current according to the corrected short-circuit impact coefficient.

9. A computing device comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions, when executed by a processor, implement the steps of the method according to any one of claims 1 to 7.

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