Simulation method, device and equipment for short-circuit fault of tap changer of converter transformer

Abstract

The application relates to the technical field of power system equipment fault, and discloses a simulation method, device and equipment for short-circuit fault of a tapping switch of a converter transformer, wherein the method comprises the following steps: performing inductance simulation on a three-dimensional finite element model of the converter transformer under a specified inter-stage short-circuit working condition of the tapping switch; obtaining an initial inductance matrix of each winding according to the inductance simulation result, and converting the initial inductance matrix into a target inductance matrix based on a three-winding transformer model; determining three-winding resistance parameters corresponding to the specified inter-stage short-circuit working condition, and constructing an inter-stage short-circuit fault model of the converter transformer according to the target inductance matrix and the three-winding resistance parameters; and solving the inter-stage short-circuit fault model to obtain a fault simulation result of the converter transformer under the specified inter-stage short-circuit working condition according to a solving result. The application greatly improves the efficiency and accuracy of the inter-stage short-circuit fault simulation, and is beneficial to efficient verification of the reliability of a control and protection device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and particularly relates to a simulation method, device and equipment for short-circuit fault of a tap changer of a converter transformer. BACKGROUND

[0002] As one of important devices for realizing energy conversion and energy transmission in an extra-high voltage direct current (EHVDC) transmission project, a converter transformer is mainly used to meet the voltage regulation requirement of isolating AC and DC systems. A tap changer is an important component indispensable for the converter transformer to realize voltage regulation function. In a normal operation process, by changing a tap position of the tap changer, the number of turns of a voltage regulation winding connected to the converter transformer can be regulated, so as to achieve the purpose of adjusting the turns ratio.

[0003] However, due to the compact and complex internal structure of the tap changer, the cumbersome switching steps and the influence of improper operation, the inter-stage short-circuit fault of the tap changer is prone to occur, which further causes the winding of the converter transformer to vibrate violently and the insulation to be damaged, and even causes the converter transformer to explode and catch fire. SUMMARY

[0004] The present application provides a simulation method, device and equipment for short-circuit fault of a tap changer of a converter transformer, which solves the technical problem that the inter-stage short-circuit fault of the tap changer causes the converter transformer to be damaged and even causes a safety accident. Based on a finite element model of the converter transformer, a target inductance matrix of each winding is accurately and efficiently obtained, and then real-time working condition simulation is performed on the inter-stage short-circuit of the converter transformer based on the target inductance matrix, which greatly improves the efficiency and accuracy of the inter-stage short-circuit fault simulation, and is beneficial to efficiently verifying the reliability of a protection device.

[0005] In order to achieve the above purpose, the main technical scheme adopted by the present application includes:

[0006] In a first aspect, an embodiment of the present application provides a simulation method for short-circuit fault of a tap changer of a converter transformer, the converter transformer comprising a plurality of windings, and the method comprising:

[0007] performing inductance simulation on a three-dimensional finite element model of the converter transformer under a specified inter-stage short-circuit working condition of the tap changer;

[0008] obtaining an initial inductance matrix of each winding according to the inductance simulation result, and converting the initial inductance matrix into a target inductance matrix based on a three-winding transformer model;

[0009] determining a three-winding resistance parameter corresponding to the specified inter-stage short-circuit working condition, and constructing an inter-stage short-circuit fault model of the converter transformer according to the target inductance matrix and the three-winding resistance parameter;

[0010] Solve the inter-stage short-circuit fault model to obtain a fault simulation result of the converter transformer under the specified inter-stage short-circuit working condition according to a solution result.

[0011] The tap changer short-circuit fault simulation method provided in the embodiments of the present application obtains an initial inductance matrix by using a three-dimensional finite element model, and then converts the initial inductance matrix into a target inductance matrix by using a three-winding transformer model, so as to equivalently convert the complex electromagnetic condition when the tap changer is in an inter-stage short-circuit state into a three-winding transformer model with clear physical meaning, realize data dimension reduction processing under the condition of meeting the actual working condition, ensure the accuracy of finite element calculation, simplify the data processing process, greatly improve the efficiency and accuracy of the inter-stage short-circuit fault simulation, and facilitate efficient verification of the reliability of the control and protection device, so as to effectively avoid the damage risk of the converter transformer caused by the inter-stage short-circuit fault.

[0012] Optionally, in some embodiments of the present application, the inductance simulation on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit working condition of the tap changer comprises:

[0013] An excitation simulation signal is input into the three-dimensional finite element model to perform inductance simulation according to the excitation simulation signal.

[0014] The embodiments of the present application apply an excitation signal to the three-dimensional finite element model, so as to more accurately obtain an inductance simulation result, provide a more reliable data basis for subsequent steps of obtaining an initial inductance matrix and constructing a fault model according to the result, and further improve the accuracy of the entire inter-stage short-circuit fault simulation.

[0015] Optionally, in some embodiments of the present application, the three-dimensional finite element model is constructed in the following manner:

[0016] Geometric parameters are determined according to the actual structure of the converter transformer, so as to construct a three-dimensional geometric model of the converter transformer according to the geometric parameters;

[0017] The three-dimensional geometric model is subjected to finite element meshing, so as to obtain the three-dimensional finite element model according to a meshing result.

[0018] Optionally, in some embodiments of the present application, the initial inductance matrix of each winding is obtained according to the inductance simulation result in the following manner:

[0019] An inductance parameter export command is called, and the inductance simulation result is processed according to the inductance parameter export command, so as to obtain the initial inductance matrix according to a processing result.

[0020] The initial inductance matrix can characterize the self-inductance and mutual inductance between each winding. In this embodiment, the initial inductance matrix characterizing the self-inductance and mutual inductance of each winding is accurately obtained from the inductance simulation results by calling the inductance parameter export command. This fully utilizes the high precision characteristics of the three-dimensional finite element model, which is beneficial to improving the efficiency and accuracy of short-circuit fault simulation between tap changer stages.

[0021] Optionally, in some embodiments of this application, the converter transformer includes a plurality of column cores, and the conversion of the initial inductance matrix into a target inductance matrix based on a three-winding transformer model includes:

[0022] Obtain the grid-side current proportionality coefficient and valve-side current proportionality coefficient of each column of the converter transformer core, and convert the initial inductance matrix into the first equivalent inductance matrix corresponding to the three-winding transformer model based on the grid-side current proportionality coefficient and the valve-side current proportionality coefficient.

[0023] The second equivalent inductance matrix of the three-winding transformer model is determined based on the calculated relationship between the leakage inductance, the excitation branch inductance, and the three-winding voltage and three-winding current of the three-winding transformer model.

[0024] The target inductance matrix is ​​determined based on the first equivalent inductance matrix and the second equivalent inductance matrix.

[0025] In this embodiment, the initial inductance matrix is ​​converted into a first equivalent inductance matrix by using the grid-side current proportionality coefficient and the valve-side current proportionality coefficient of each column core. Then, the first equivalent inductance matrix and the second equivalent inductance matrix are compared to obtain the target inductance matrix. The target inductance matrix can characterize the equivalent leakage inductance and excitation branch inductance of each winding corresponding to the three-winding transformer model. Thus, the complex electromagnetic situation of inter-stage short circuit of tap changer is equivalent to a three-winding transformer model with clear physical meaning. While ensuring the accuracy of finite element calculation, the data processing dimension is optimized. Compared with related technologies, it does not have ill-conditioned characteristics, simplifies the processing process, and greatly improves the efficiency and accuracy of inter-stage short circuit fault simulation.

[0026] Optionally, in some embodiments of this application, the three-winding transformer model includes the primary side, the secondary side, and the fault port corresponding to the specified inter-stage short-circuit condition;

[0027] Determining the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition includes:

[0028] A self-developed model is constructed based on the three-winding transformer model, and a system external circuit corresponding to the self-developed model is constructed, wherein the system external circuit includes the short-circuit resistance corresponding to the specified inter-stage short-circuit condition;

[0029] The resistance of the first winding on the primary side and the resistance of the second winding on the secondary side are determined according to the self-developed model.

[0030] The resistance of the third winding of the fault port is determined based on the impedance coupling relationship between the short-circuit resistance of the external circuit of the system and the winding corresponding to the fault port.

[0031] The three winding resistance parameters are determined based on the first winding resistance, the second winding resistance, and the third winding resistance.

[0032] Optionally, in some embodiments of this application, the target inductance matrix includes the primary leakage inductance, secondary leakage inductance, equivalent leakage inductance of the branch where the fault port is located, and excitation branch inductance of the three-winding transformer model.

[0033] The step of constructing the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three winding resistance parameters includes:

[0034] Based on the calculated relationship between the voltage and current on the primary side, the resistance of the first winding, the leakage inductance of the primary side, and the inductance of the excitation branch in the Laplace domain, the voltage equation on the primary side is determined.

[0035] Based on the calculated relationship between the voltage and current on the secondary side, the resistance of the second winding, the leakage inductance on the secondary side, and the inductance of the excitation branch in the Laplace domain, the voltage equation on the secondary side is determined.

[0036] Based on the calculated relationship between the voltage and current of the fault port, the resistance of the third winding, the equivalent leakage inductance, and the inductance of the excitation branch in the Laplace domain, the voltage equation of the fault port is determined.

[0037] The inter-stage short-circuit fault model is determined based on the primary-side voltage equation, the secondary-side voltage equation, and the fault port voltage equation.

[0038] Based on the calculation relationships of voltage, current, winding impedance, and inductance in the Laplace domain of the three-winding transformer model, the voltage equations for the primary side, secondary side, and fault port are determined respectively. This enables the rapid construction of inter-stage short-circuit fault models on a real-time simulation platform, which is beneficial to improving the real-time performance of subsequent tap changer short-circuit fault simulation results.

[0039] Optionally, in some embodiments of this application, solving the inter-stage short-circuit fault model to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results includes:

[0040] The inter-stage short-circuit fault model is solved in the time domain to obtain the inter-stage fault current of the converter transformer based on the solution results, and the inter-stage fault current is used as the fault simulation result.

[0041] By solving the inter-stage short-circuit fault model in the time domain, the model can be transformed from the Laplace domain to the actual time domain, which more intuitively reflects the electrical characteristics of the converter transformer under a specified inter-stage short-circuit condition. This improves the real-time performance of the tap changer short-circuit fault simulation results, provides effective test basis for the reliability verification of control and protection devices, and helps prevent the risk of damage to the converter transformer.

[0042] Secondly, embodiments of this application provide a simulation device for a short-circuit fault in the tap changer of a converter transformer, wherein the converter transformer includes a plurality of windings, and the device includes:

[0043] The inductance simulation module is used to perform inductance simulation on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer.

[0044] The target inductance matrix generation module is used to obtain the initial inductance matrix of each winding based on the inductance simulation results, and convert the initial inductance matrix into the target inductance matrix based on the three-winding transformer model;

[0045] The fault modeling module is used to determine the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition, and to construct the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters.

[0046] The fault simulation module is used to solve the inter-stage short-circuit fault model to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results.

[0047] The tap changer short-circuit fault simulation device proposed in this application uses a three-dimensional finite element model to obtain the initial inductance matrix, and then converts the initial inductance matrix into the target inductance matrix through a three-winding transformer model. This allows the complex electromagnetic situation of inter-stage short circuits in tap changers to be equivalent to a three-winding transformer model with clear physical meaning. Under the condition of meeting actual working conditions, data dimensionality reduction is achieved, which can not only ensure the accuracy of finite element calculation, but also simplify the data processing process, greatly improving the efficiency and accuracy of inter-stage short-circuit fault simulation. This is conducive to the efficient verification of the reliability of control and protection devices, so as to effectively avoid the risk of converter damage caused by inter-stage short-circuit faults.

[0048] Thirdly, embodiments of this application provide a computer device, including a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the short-circuit fault simulation method for the tap changer of the converter transformer described in the above embodiments. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0050] Figure 1 The flowchart of a short-circuit fault simulation method for a converter transformer tap changer proposed in this application embodiment is as follows: Figure 1 ;

[0051] Figure 2 This is a schematic diagram of the three-dimensional geometric model of the converter transformer proposed in this application in one embodiment;

[0052] Figure 3 This is a schematic diagram of the structure of a three-dimensional finite element model of the converter transformer proposed in this application in one embodiment;

[0053] Figure 4 This is a schematic diagram of the self-developed model and external circuitry proposed in this application in one embodiment;

[0054] Figure 5(a) is a schematic diagram of the simulation results of inter-stage fault current in one embodiment of this application;

[0055] Figure 5(b) is a schematic diagram of the simulation results of the grid-side current of the converter transformer in one embodiment of this application;

[0056] Figure 6(a) is a schematic diagram of the simulation results of inter-stage fault current in another embodiment of this application;

[0057] Figure 6(b) is a schematic diagram of the simulation results of the grid-side current of the converter transformer in another embodiment of this application;

[0058] Figure 7 This is a schematic diagram of the structure of a short-circuit fault simulation device for a converter transformer tap changer proposed in an embodiment of this application;

[0059] Figure 8 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] Converter transformers, as crucial equipment in ultra-high voltage direct current (UHVDC) transmission projects for energy conversion and transmission, undertake multiple important tasks, including isolating AC / DC systems and providing the adjustable AC voltage required by converter valves. They primarily meet the voltage regulation needs of isolated AC / DC systems. Compared to conventional power transformers, converter transformers must simultaneously withstand the combined stresses of AC and DC voltages, as well as the stresses of polarity reversal. They also have a wider voltage regulation range and more frequent voltage regulation requirements, all of which pose significant challenges to the insulation design, manufacturing, and safe operation of converter transformers and their components.

[0062] Tap changers are essential components of converter transformers for voltage regulation, playing a crucial role in compensating for AC grid voltage fluctuations, optimizing DC system control angles, and enabling DC step-down operation. During normal operation, changing the tap position allows adjustment of the number of turns in the regulating winding connected to the converter transformer, thereby adjusting the turns ratio.

[0063] However, due to the compact and complex internal structure of the tap changer, the cumbersome switching steps, and the need for precise timing, the probability of insulation degradation and high-energy arcing faults is relatively high. With the increase in voltage regulation frequency, the rate of malfunction and failure of the tap changer also increases accordingly. Carbon particles, insulating fibers, and metal debris are generated in the oil chamber, which in severe cases may trigger high-energy arc discharge between adjacent conductors or contacts, i.e., inter-stage short circuit faults. When an inter-stage short circuit fault occurs, a huge short-circuit current flows through the voltage regulating circuit composed of the regulating winding and the tap changer, causing severe vibration of the winding and insulation damage. Simultaneously, the insulating oil in the tap changer's oil chamber vaporizes and decomposes, producing large amounts of flammable gases such as hydrogen and acetylene. Furthermore, due to the small size and compact internal structure of the tap changer's oil chamber, an inter-stage short circuit will cause a sudden increase in pressure within the narrow chamber, which could potentially lead to oil spraying or even a serious explosion and fire accident in the converter transformer.

[0064] According to an embodiment of this application, a simulation method for short-circuit faults of tap changers in converter transformers 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.

[0065] This embodiment provides a simulation method for tap changer short-circuit faults in converter transformers, applicable to two-limb, multi-winding converter transformers. Figure 1 This is a flowchart of a tap changer short-circuit fault simulation method according to an embodiment of this application, such as... Figure 1 As shown, the process includes the following steps:

[0066] Step S1: Perform inductance simulation on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer.

[0067] Specifically, two designated stages of the tap changer are first selected for simulation analysis of short-circuit conditions between designated stages. For example, the +9 and +10 stages of the tap changer are selected as designated stages, and inductance simulation is performed on the three-dimensional finite element model to facilitate subsequent analysis of the impact of inter-stage short-circuit faults on the performance of the converter transformer.

[0068] Step S3: Obtain the initial inductance matrix of each winding based on the inductance simulation results, and convert the initial inductance matrix into the target inductance matrix based on the three-winding transformer model.

[0069] Specifically, after completing the inductance simulation, an initial inductance matrix is ​​extracted from the simulation results. This initial inductance matrix represents the self-inductance and mutual inductance between the windings of the converter. Since the three-winding transformer model has specific advantages and clear physical meaning in analyzing the electromagnetic characteristics of circuits, it can simplify the analysis of complex electromagnetic situations. Therefore, based on the three-winding transformer model, relevant electromagnetic theories and mathematical methods are used to transform the initial inductance matrix into a target inductance matrix. The target inductance matrix represents the equivalent leakage inductance of each winding and the inductance of the excitation branch under the three-winding transformer model. The target inductance matrix provides an accurate data foundation for the subsequent construction of an inter-stage short-circuit fault model.

[0070] Step S5: Determine the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition, and construct the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters.

[0071] Specifically, based on the relationship between the target inductance matrix and the resistance parameters of the three windings and the voltage and current at each winding port of the three-winding transformer model, an inter-stage short-circuit fault model of the converter transformer is constructed, thereby accurately simulating the actual operating state of the converter transformer under a specified inter-stage short-circuit condition.

[0072] Step S7: Solve the inter-stage short-circuit fault model to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results.

[0073] Specifically, by solving the inter-stage short-circuit fault model, the grid-side current change of the converter transformer under a specified inter-stage short-circuit condition is obtained. Then, based on the fault simulation results, a reliability verification environment is set for the control and protection device to ensure the effective protection performance of the control and protection device.

[0074] The tap changer short-circuit fault simulation method provided in this embodiment uses a three-dimensional finite element model to obtain the initial inductance matrix, and then converts the initial inductance matrix into the target inductance matrix through a three-winding transformer model. This allows the complex electromagnetic situation of inter-stage short circuits in tap changers to be equivalent to a three-winding transformer model with clear physical meaning. Under the condition of meeting actual operating conditions, data dimensionality reduction is achieved, which can not only ensure the accuracy of finite element calculations, but also simplify the data processing process, greatly improving the efficiency and accuracy of inter-stage short-circuit fault simulation. This is beneficial for the efficient verification of the reliability of control and protection devices, so as to effectively avoid the risk of converter damage caused by inter-stage short-circuit faults.

[0075] In some embodiments of this application, the three-dimensional finite element model is constructed in the following manner:

[0076] The geometric parameters of the converter transformer are determined based on its actual structure, and a three-dimensional geometric model of the converter transformer is constructed based on these parameters. Finite element meshing is then performed on the three-dimensional geometric model to obtain a three-dimensional finite element model.

[0077] Specifically, taking the ZZDFPZ-415000 / 750-400 converter transformer as an example, Figure 2 This paper presents a 3D geometric model of a converter transformer drawn using SpaceClaim software, which constructs the windings and core of the converter transformer at a 1:1 full scale. In actual engineering, to reduce eddy current losses during operation, the transformer core is actually manufactured by laminating silicon steel sheets. To reduce the complexity of the core structure and the difficulty of mesh generation in finite element software, this embodiment simplifies it to a smooth-surfaced cylinder or elliptical cylinder. Furthermore, the winding coils are actually composed of multiple parallel wires wound in series, and the grid-side and valve-side windings of the converter transformer often adopt a disc-shaped structure. Therefore, in the modeling process of the 3D geometric model, the winding coils can be approximated as a concentric cylindrical structure. The voltage regulating winding usually adopts a layered structure, with only a portion connected to the circuit. Therefore, this embodiment simplifies the voltage regulating winding to several segments of concentric cylindrical structure, and the gap between each voltage regulating segment is taken from the actual height of the interlayer spacers in the voltage regulating winding.

[0078] In this embodiment, a project file is created in ANSYS, and the ANSYS Maxwell 3D Design module is selected. The aforementioned three-dimensional geometric model is imported into the ANSYS Maxwell 3D Design module, and the three-dimensional geometric model is configured and meshed as follows to obtain the following result. Figure 3 The three-dimensional finite element model shown:

[0079] (1) Set the solver: Set the Maxwell 3D Design solver to transient field solver, set the coordinate system to Cartesian (XY), and set the calculated inductance matrix to apparent inductance matrix.

[0080] (2) Set the solution boundary: Draw the equivalent calculation region according to the actual size of the converter transformer tank shell, select each face of the calculation region, and set the tank boundary condition as an insulating boundary.

[0081] (3) Set the material properties of each part of the model: The converter transformer includes several column cores. The winding material of the converter transformer is set to copper, with a relative permeability of 0.999991 and an electrical conductivity of 5.8×107S / m. The transformer core is made of low carbon steel 1008.

[0082] (4) Apply excitation to the winding model: Divide the voltage regulating winding of the converter transformer into 16 segments, set the winding excitation, set the winding as a hinge conductor, and use external excitation as input;

[0083] (5) Finite element mesh generation: The three-dimensional geometric model is meshed, and the maximum element length of the mesh for the oil tank, iron core and winding parts is limited to 1000mm, 400mm and 200mm respectively.

[0084] (6) Add the solver Setup and set the calculation step size and total time of the magnetic field simulation to 0.1ms and 1ms respectively.

[0085] In some embodiments of this application, step S1 may include the following steps:

[0086] Step S11: Input the simulation excitation signal into the three-dimensional finite element model to perform inductance simulation based on the simulation excitation signal.

[0087] Furthermore, in some embodiments of this application, an external excitation is added in Simplorer based on the ANSYS platform to perform inductance simulation on the three-dimensional finite element model under external excitation. Specifically, the external excitation is configured as an AC power supply with an effective value of 447.4kV and a frequency of 50Hz, and a load resistor of 100Ω is connected between the transformer element lead-out interface and the external excitation.

[0088] Therefore, the embodiments of this application apply excitation signals to the three-dimensional finite element model, thereby obtaining inductance simulation results more accurately. This provides a more reliable data foundation for subsequent steps such as obtaining the initial inductance matrix and constructing the fault model based on the results, further improving the accuracy of the entire inter-stage short-circuit fault simulation.

[0089] In some embodiments of this application, step S3 may include the following steps:

[0090] Step S31: Call the inductance parameter export command and process the inductance simulation results according to the inductance parameter export command to obtain the initial inductance matrix based on the processing results.

[0091] Specifically, in some embodiments of this application, the command Results\Create Standard Report\Rectangular Plot is executed in Maxwell 3D Design1, all inductors are selected in Winding, and the above-mentioned initial inductance matrix is ​​exported. The initial inductance matrix includes the self-inductance and mutual inductance of each winding.

[0092] Therefore, in this embodiment, the initial inductance matrix can characterize the self-inductance and mutual inductance between each winding. This embodiment accurately obtains the initial inductance matrix characterizing the self-inductance and mutual inductance of each winding from the inductance simulation results by calling the inductance parameter export command. This fully utilizes the high precision characteristics of the three-dimensional finite element model, which is beneficial to improving the efficiency and accuracy of short-circuit fault simulation between tap changer stages.

[0093] Step S33: Obtain the grid-side current ratio coefficient and valve-side current ratio coefficient of each column core of the converter transformer, and convert the initial inductance matrix into the first equivalent inductance matrix corresponding to the three-winding transformer model based on the grid-side current ratio coefficient and valve-side current ratio coefficient.

[0094] Specifically, the grid-side current proportionality coefficient k pm The valve-side current proportionality coefficient k represents the ratio of the grid-side current to the total grid-side current in the m-th core. sm Characterizes the ratio of the valve-side current of the m-th core to the total valve-side current. The grid-side current proportionality coefficient k. pm and valve side current proportionality coefficient k smUsed for subsequent transformation calculations of the initial inductance matrix.

[0095] In this embodiment of the application, the initial inductance matrix between multiple windings of the converter transformer is transformed into the first equivalent inductance matrix of the three-winding transformer model in MATLAB. The transformation calculation is shown in the following formula (1):

[0096]

[0097] In the formula, L pp L represents the self-inductance of the primary winding in a three-winding transformer model. ps L represents the mutual inductance between the primary and secondary windings in a three-winding transformer model. pf L represents the mutual inductance between the primary winding and the fault winding in a three-winding transformer model. sp L represents the mutual inductance between the secondary and primary windings in a three-winding transformer model. ss L represents the self-inductance of the secondary winding in a three-winding transformer model. sf L represents the mutual inductance between the secondary winding and the fault winding in a three-winding transformer model. fp L represents the mutual inductance between the fault winding and the primary winding in a three-winding transformer model. fs L represents the mutual inductance between the fault winding and the secondary winding in a three-winding transformer model. ff L represents the self-inductance of the faulty winding in a three-winding transformer model. ij Let i be the mutual inductance between the i-th winding and the j-th winding of the converter transformer, iep and jep be the number of primary windings of the converter transformer, ies and jes be the number of secondary windings of the converter transformer, ief and jef be the number of fault windings of the converter transformer, and iem and jem be the number of iron cores of the converter transformer.

[0098] As can be seen from the above formula (1), the initial inductance matrix in this embodiment is [L ij The first equivalent inductance matrix is: Furthermore, in the three-winding transformer model, the voltage, current, and first equivalent inductance matrix of the three windings have the relationship shown in the following formula (2):

[0099]

[0100] In the formula, u p u is the primary winding voltage in a three-winding transformer model. s u is the secondary winding voltage in a three-winding transformer model. f Let i be the fault winding voltage in the three-winding transformer model. p Let i be the primary winding current in a three-winding transformer model. sLet i be the secondary winding current in a three-winding transformer model. f This refers to the fault winding current in a three-winding transformer model.

[0101] Step S35: Determine the second equivalent inductance matrix of the three-winding transformer model based on the calculated relationship between the leakage inductance, excitation branch inductance, and the three-winding voltage and current.

[0102] Specifically, the calculation relationship between the leakage inductance, excitation branch inductance, and three-winding voltage and current of the three-winding transformer model is shown in the following formula (3):

[0103]

[0104] In the formula, L p For the primary leakage inductance of a three-winding transformer model, L s For the secondary leakage inductance of a three-winding transformer model, L x For the excitation branch inductance, k ps k is the voltage ratio between the primary and secondary windings. pf This is the voltage ratio between the primary winding and the faulty winding.

[0105] As can be seen from the above formula (3), the second equivalent inductance matrix is:

[0106]

[0107] Step S37: Determine the target inductance matrix based on the first equivalent inductance matrix and the second equivalent inductance matrix.

[0108] Specifically, based on the comparison of formulas (2) and (3) above, the following formula (4) can be obtained:

[0109]

[0110] The target inductance matrix is ​​then obtained as shown in the following formula (5):

[0111]

[0112] Therefore, in this embodiment, the initial inductance matrix is ​​converted into a first equivalent inductance matrix by using the grid-side current proportionality coefficient and the valve-side current proportionality coefficient of each column core. Then, the first equivalent inductance matrix and the second equivalent inductance matrix are compared to obtain the target inductance matrix. The target inductance matrix can characterize the equivalent leakage inductance and excitation branch inductance of each winding corresponding to the three-winding transformer model. Thus, the complex electromagnetic situation of inter-stage short circuit of the tap changer is equivalent to a three-winding transformer model with clear physical meaning. While ensuring the accuracy of finite element calculation, the data processing dimension is optimized. Compared with related technologies, it does not have ill-conditioned characteristics, simplifies the processing process, and greatly improves the efficiency and accuracy of inter-stage short circuit fault simulation.

[0113] In some embodiments of this application, the three-winding transformer model includes the primary side, the secondary side, and the fault port corresponding to a specified inter-stage short-circuit condition. Further, step S5 above may include the following steps:

[0114] Step S51: Construct a self-developed model based on the three-winding transformer model, and construct the corresponding system external circuit of the self-developed model. The system external circuit includes the short-circuit resistance corresponding to the specified inter-stage short-circuit condition.

[0115] In some embodiments of this application, inter-level short-circuit conditions of +9 and +10 levels are used as examples. Figure 4 This illustrates a self-developed model built using RSCAD and its corresponding external system circuitry. For example... Figure 4 As shown, based on the self-developed model, the short-circuit resistance R is determined. fault and short-circuit resistor R fault The circuit breaker S, connected in series with the inter-stage short-circuit fault circuit breaker S, is connected between the +9 and +10 voltage regulating windings of the converter transformer, thus forming an inter-stage short-circuit fault circuit.

[0116] Among them, the inter-stage short-circuit fault of the converter transformer tap changer involves the internal circuit topology of the tap changer, the voltage regulating leads, and the voltage regulating winding of the converter transformer. In this embodiment, the resistance R of each voltage regulating lead is calculated based on the resistivity provided by the manufacturer. lead The resistance is 0.04Ω, and the loop resistance of the inter-stage short-circuit fault loop is determined as shown in the following formula (6):

[0117] R sc =2R lead +R0+R fault Formula (6)

[0118] In the formula, R sc R0 is the loop resistance of the inter-stage short-circuit fault circuit mentioned above, and R0 is the total resistance of the internal conductors and contacts of the tap changer, which is much smaller than 2R. lead This can be ignored in the calculation. R faultIn this embodiment, the value is 0.01Ω.

[0119] Figure 4 The configuration of the external circuitry corresponding to the self-developed model is also shown, where E S For a three-phase voltage source, Z S L is the line impedance. d For smoothing reactors, N is the grid-side neutral point. The grid-side (Line Side) of the converter transformer refers to the winding side (high-voltage side) directly connected to the AC grid, responsible for receiving or transmitting AC power. The valve side (Valve Side) of the converter transformer refers to the winding side (low-voltage side) connected to the converter valve (such as a thyristor / IGBT bridge), realizing the conversion between AC and DC. The grid-side windings corresponding to each core of the converter transformer are connected in parallel and then connected to the external circuit of the system. The voltage regulating windings are connected to the taps of the tap changer. The voltage regulating leads corresponding to each core are connected in parallel and then connected to the grid-side neutral point. The valve-side windings corresponding to each core are connected in parallel. The valve side of the converter transformer is connected in a star / delta (YD) hybrid configuration. The valve-side output is connected to the rectifier. The configuration between the self-developed model and the external circuit of the system is determined by the above connection method.

[0120] For the faulty double-star (YY) transformer bank, three independent transformers were used for detailed modeling, while the remaining transformer banks were built directly using the system's built-in standardized transformer bank modules. Furthermore, the system's external circuitry was operated at maximum capacity, with AC filters built according to actual parameters, and standard modules from the system's component library selected for the rectifier section.

[0121] Step S52: Determine the first winding resistance on the primary side and the second winding resistance on the secondary side based on the self-developed model.

[0122] Specifically, the first winding resistance is the resistance of the primary winding of the converter transformer relative to the primary side of the three-winding transformer model, and the second winding resistance is the resistance of the secondary winding of the converter transformer relative to the primary side of the three-winding transformer model. That is, the first winding resistance and the second winding resistance are determined by the transformer winding structure and winding material.

[0123] Step S53: Determine the resistance of the third winding of the fault port based on the impedance coupling relationship between the short-circuit resistance of the external circuit and the winding corresponding to the fault port.

[0124] Specifically, the resistance of the third winding is the resistance of the fault branch where the short-circuit resistance is located relative to the fault port of the three-winding transformer model.

[0125] Step S54: Determine the resistance parameters of the three windings based on the resistance of the first winding, the resistance of the second winding, and the resistance of the third winding.

[0126] Specifically, in this embodiment, the resistance parameter [r] of the three windings is [r p ,r s ,r f ], where r p Let r be the resistance of the first winding. s For the resistance of the second winding, r f This is the resistance of the third winding.

[0127] Step S54: Determine the primary side voltage equation based on the calculated relationship between the primary side voltage and current, the first winding resistance, the primary side leakage inductance, and the excitation branch inductance in the Laplace domain.

[0128] Specifically, the above primary-side voltage equation is shown in the following formula (7):

[0129] v1(t)=r p i1(t)+jωL p i1(t)+jωL x Formula (7) is (i1(t)+i2(t)+i3(t))

[0130] In the formula, v1(t) is the primary side voltage in the three-winding transformer model, i1(t) is the primary side current in the three-winding transformer model, i2(t) is the secondary side current in the three-winding transformer model, i3(t) is the fault port current in the three-winding transformer model, and the meanings of other variables in the formula are as described in the previous formula.

[0131] Step S55: Determine the voltage equation of the secondary side based on the calculated relationship between the voltage and current of the secondary side, the resistance of the second winding, the leakage inductance of the secondary side, and the inductance of the excitation branch in the Laplace domain.

[0132] Specifically, the above secondary side voltage equation is shown in the following formula (8):

[0133] v2(t)=r s i2(t)+jωL s i2(t)+jωL x Formula (8) is (i1(t)+i2(t)+i3(t))

[0134] In the formula, v2(t) is the secondary side voltage in the three-winding transformer model, and the meanings of the variables in other formulas are as described in the previous formulas.

[0135] Step S56: Determine the voltage equation of the fault port based on the calculated relationship between the voltage and current of the fault port, the resistance of the third winding, the equivalent leakage inductance, and the inductance of the excitation branch in the Laplace domain.

[0136] Specifically, the above-mentioned fault port voltage equation is shown in the following formula (9):

[0137] v3(t)=r f i3(t)+jωL f i3(t)+jωL x Formula (9) is (i1(t)+i2(t)+i3(t))

[0138] In the formula, v3(t) is the fault port voltage in the three-winding transformer model, and the meanings of other variables in the formula are as described in the previous formula.

[0139] Step S57: Determine the inter-stage short-circuit fault model based on the primary side voltage equation, the secondary side voltage equation, and the fault port voltage equation.

[0140] Specifically, the inter-level short-circuit fault model is constructed using the above formulas (7) to (9).

[0141] Therefore, based on the calculation relationship of voltage, current, winding impedance and inductance in the Laplace domain in the three-winding transformer model, the voltage equations of the primary side, secondary side and fault port are determined respectively, thereby enabling the rapid construction of inter-stage short-circuit fault models on the real-time simulation platform, which is beneficial to improving the real-time performance of subsequent tap changer short-circuit fault simulation results.

[0142] In some embodiments of this application, step S7 may include the following steps:

[0143] Step S71: Solve the inter-stage short-circuit fault model in the time domain to obtain the inter-stage fault current of the converter transformer based on the solution results, and use the inter-stage fault current as the fault simulation result.

[0144] Specifically, the above formulas (7) to (9) are transformed from the Laplace domain to the time domain for solution, and processed using the trapezoidal integral method to obtain the solution result shown in the following formula (10):

[0145] [i(t)]=[g tr Formula (10) is: [v(t)]+[ih(t)]

[0146] In the formula, [i(t)] is the current matrix of the three-winding transformer model at the current time t, v(t) is the voltage matrix of the three-winding transformer model at the current time t, and [g tr [ih(t)] is the voltage function across the transformer terminals of the three-winding transformer model at the current time t, and [ih(t)] is the current function flowing into the transformer at the previous time t-Δt of the three-winding transformer model.

[0147] Among them, [g] is calculated by the following formula (11). tr [ih(t)] is calculated using the following formula (12):

[0148]

[0149] In the formula, Δt is the preset simulation step size, and [r] is the resistance parameter of the three windings, i.e., [r] = [r] p ,r s ,r f [l] represents the target inductance matrix, i.e., [l] = [L]. p ,L s ,L f ,L x [v(t-Δt)] is the voltage matrix of the three-winding transformer model at the previous time t-Δt, and i(t-Δt) is the current matrix of the three-winding transformer model at the previous time t-Δt.

[0150] Therefore, by solving the inter-stage short-circuit fault model in the time domain, the embodiments of this application can transform the model from the Laplace domain to the actual time domain, more intuitively reflecting the electrical characteristics of the converter transformer under a specified inter-stage short-circuit condition, thereby improving the real-time performance of the tap changer short-circuit fault simulation results, providing effective test basis for the reliability verification of the control and protection device, and thus helping to prevent the risk of damage to the converter converter.

[0151] Figure 5(a) shows the simulation results of the inter-stage fault current under the +9 / +10 stage inter-stage short-circuit condition. As shown in Figure 5(a), under the +9 / +10 stage inter-stage short-circuit fault condition, the high-amplitude inter-stage fault current will flow through the fault turn, the voltage regulating lead, and the fault resistor. This short-circuit circulating current reaches a peak value of 33.64kA after the fault. Figure 5(b) shows the simulation results of the converter transformer grid-side current under the +9 / +10 stage inter-stage short-circuit condition. As shown in Figure 5(b), before the fault, the converter transformer grid-side current exhibits a symmetrical trapezoidal waveform. After the +9 / +10 stage inter-stage fault occurs, the grid-side current of the non-faulty phase converter transformer does not change significantly, while the grid-side current of the faulty phase converter transformer shows a significant increase, with the effective value increasing from 0.78kA to 0.97kA, an increase of 25.34%.

[0152] Figure 6(a) shows the simulation results of the inter-stage fault current under the inter-stage short-circuit condition of the -5 / -4 stage. As shown in Figure 6(a), the high-amplitude inter-stage fault current will flow through the fault turn, the voltage regulating lead, and the fault resistor. This short-circuit circulating current reaches a peak value of 48.60 kA after the fault. Figure 6(b) shows the simulation results of the grid-side current of the converter transformer under the inter-stage short-circuit condition of the -5 / -4 stage. As shown in Figure 6(b), the grid-side current of the converter transformer in the faulted phase shows a significant increase, with the effective value increasing from 0.90 kA to 1.23 kA, and the amplitude increasing by 36.13%.

[0153] Accordingly, please refer to Figure 7This application provides a simulation device for a short-circuit fault in the tap changer of a converter transformer. The converter transformer includes several windings, and the device includes:

[0154] The inductance simulation module 100 is used to perform inductance simulation on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer. For details, please refer to step S1.

[0155] The target inductance matrix generation module 200 is used to obtain the initial inductance matrix of each winding based on the inductance simulation results, and to convert the initial inductance matrix into the target inductance matrix based on the three-winding transformer model. For details, please refer to step S3.

[0156] The fault modeling module 300 is used to determine the three-winding resistance parameters corresponding to a specified inter-stage short-circuit condition, and to construct an inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters. For details, please refer to step S5.

[0157] The fault simulation module 400 is used to solve the inter-stage short-circuit fault model to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results. For details, please refer to step S7.

[0158] The tap changer short-circuit fault simulation device proposed in this application uses a three-dimensional finite element model to obtain the initial inductance matrix, and then converts the initial inductance matrix into the target inductance matrix through a three-winding transformer model. This allows the complex electromagnetic situation of inter-stage short circuits in tap changers to be equivalent to a three-winding transformer model with clear physical meaning. Under the condition of meeting actual working conditions, data dimensionality reduction is achieved, which can not only ensure the accuracy of finite element calculation, but also simplify the data processing process, greatly improving the efficiency and accuracy of inter-stage short-circuit fault simulation. This is conducive to the efficient verification of the reliability of control and protection devices, so as to effectively avoid the risk of converter damage caused by inter-stage short-circuit faults.

[0159] In some embodiments of this application, the inductor simulation module 100 includes:

[0160] Excitation sub-unit 110 is used to input simulation excitation signals to the configured three-dimensional finite element model in order to perform inductance simulation based on the simulation excitation signals.

[0161] In some embodiments of this application, the target inductance matrix generation module 200 includes:

[0162] The initial inductance matrix subunit 210 is used to call the inductance parameter export command and process the inductance simulation results according to the inductance parameter export command to obtain the initial inductance matrix based on the processing results.

[0163] The first equivalent conversion subunit 220 is used to obtain the grid-side current proportional coefficient and valve-side current proportional coefficient of each column core of the converter transformer, and convert the initial inductance matrix into the first equivalent inductance matrix corresponding to the three-winding transformer model according to the grid-side current proportional coefficient and valve-side current proportional coefficient.

[0164] The second equivalent conversion subunit 230 is used to determine the second equivalent inductance matrix of the three-winding transformer model based on the calculated relationship between the leakage inductance, excitation branch inductance and the three-winding voltage and three-winding current of the three-winding transformer model.

[0165] The target inductance matrix sub-unit 240 is used to determine the target inductance matrix based on the first equivalent inductance matrix and the second equivalent inductance matrix.

[0166] In some embodiments of this application, the fault modeling module 300 includes:

[0167] The self-developed model subunit 310 is used to construct a self-developed model based on the three-winding transformer model and to construct the corresponding system external circuit of the self-developed model. The system external circuit includes the short-circuit resistance corresponding to the specified inter-stage short-circuit condition.

[0168] The three-winding resistor subunit 310 is used to determine the first winding resistance on the primary side and the second winding resistance on the secondary side according to the self-developed model, to determine the third winding resistance of the fault port according to the impedance coupling relationship between the short-circuit resistance of the external circuit and the winding corresponding to the fault port, and to determine the three-winding resistance parameters according to the first winding resistance, the second winding resistance and the third winding resistance.

[0169] The primary-side modeling sub-unit 320 is used to determine the primary-side voltage equation based on the calculated relationship between the primary-side voltage and current, the first winding resistance, the primary-side leakage inductance, and the excitation branch inductance in the Laplace domain.

[0170] The secondary side modeling subunit 330 is used to determine the secondary side voltage equation based on the calculated relationship between the secondary side voltage and current, the second winding resistance, the secondary side leakage inductance, and the excitation branch inductance in the Laplace domain.

[0171] The fault port modeling subunit 340 is used to determine the fault port voltage equation based on the calculated relationship between the voltage and current of the fault port, the resistance of the third winding, the equivalent leakage inductance, and the inductance of the excitation branch in the Laplace domain.

[0172] Model generation sub-unit 350 is used to determine the inter-stage short-circuit fault model based on the primary side voltage equation, the secondary side voltage equation, and the fault port voltage equation.

[0173] In some embodiments of this application, the fault simulation module 400 includes:

[0174] The time-domain solver subunit 410 is used to solve the inter-stage short-circuit fault model in the time domain, so as to obtain the inter-stage fault current of the converter transformer based on the solution results, and use the inter-stage fault current as the fault simulation result.

[0175] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0176] In this embodiment, the tap changer short-circuit fault simulation device is presented in the form of functional units. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0177] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application, such as... Figure 8 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 8 Take a processor 10 as an example.

[0178] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0179] The memory 20 stores instructions executable by at least one processor 10 to cause the at least one processor 10 to perform the method shown in the above embodiments.

[0180] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0181] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0182] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0183] This application also provides a computer-readable storage medium. The methods described in this application can be implemented in hardware or firmware, or implemented as recordable on a storage medium, or implemented as computer code downloaded over a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and subsequently stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the methods shown in the above embodiments are implemented.

[0184] This application provides a computer program product including computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the method of any embodiment of this application.

[0185] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

[0186] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0187] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0188] 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.

[0189] 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.

[0190] 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 1The function specified in one or more boxes.

[0191] 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.

[0192] 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 a process, method, article, or apparatus. Without further limitation, 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 said element.

[0193] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the apparatus embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0194] The above description is merely an embodiment of this application and is 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.

[0195] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A simulation method for short-circuit faults in the tap changer of a converter transformer, characterized in that, The converter transformer includes several windings, and the method includes: Inductance simulation was performed on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer. The initial inductance matrix of each winding is obtained based on the inductance simulation results, and the initial inductance matrix is ​​converted into the target inductance matrix based on the three-winding transformer model. Determine the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition, and construct the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters; The inter-stage short-circuit fault model is solved to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results; The converter transformer includes several column cores. The process of converting the initial inductance matrix into a target inductance matrix based on a three-winding transformer model includes: Obtain the grid-side current proportionality coefficient and valve-side current proportionality coefficient of each column of the converter transformer core, and convert the initial inductance matrix into the first equivalent inductance matrix corresponding to the three-winding transformer model based on the grid-side current proportionality coefficient and the valve-side current proportionality coefficient. The second equivalent inductance matrix of the three-winding transformer model is determined based on the calculated relationship between the leakage inductance, the excitation branch inductance, and the three-winding voltage and three-winding current of the three-winding transformer model. The target inductance matrix is ​​determined based on the first equivalent inductance matrix and the second equivalent inductance matrix; The three-winding transformer model includes the primary side, the secondary side, and the fault port corresponding to the specified inter-stage short-circuit condition. Determining the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition includes: A self-developed model is constructed based on the three-winding transformer model, and a system external circuit corresponding to the self-developed model is constructed, wherein the system external circuit includes the short-circuit resistance corresponding to the specified inter-stage short-circuit condition; The resistance of the first winding on the primary side and the resistance of the second winding on the secondary side are determined according to the self-developed model. The resistance of the third winding of the fault port is determined based on the impedance coupling relationship between the short-circuit resistance of the external circuit of the system and the winding corresponding to the fault port. The resistance parameters of the three windings are determined based on the resistance of the first winding, the resistance of the second winding, and the resistance of the third winding; The target inductance matrix includes the primary leakage inductance, secondary leakage inductance, equivalent leakage inductance of the branch where the fault port is located, and excitation branch inductance of the three-winding transformer model. The construction of the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters includes: Based on the calculated relationship between the voltage and current on the primary side, the resistance of the first winding, the leakage inductance of the primary side, and the inductance of the excitation branch in the Laplace domain, the voltage equation on the primary side is determined. Based on the calculated relationship between the voltage and current on the secondary side, the resistance of the second winding, the leakage inductance on the secondary side, and the inductance of the excitation branch in the Laplace domain, the voltage equation on the secondary side is determined. Based on the calculated relationship between the voltage and current of the fault port, the resistance of the third winding, the equivalent leakage inductance, and the inductance of the excitation branch in the Laplace domain, the voltage equation of the fault port is determined. The inter-stage short-circuit fault model is determined based on the primary-side voltage equation, the secondary-side voltage equation, and the fault port voltage equation.

2. The method according to claim 1, characterized in that, The inductance simulation of the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer includes: The simulation excitation signal is input to the three-dimensional finite element model to perform inductance simulation based on the simulation excitation signal.

3. The method according to claim 1, characterized in that, The three-dimensional finite element model is constructed using the following method: The geometric parameters are determined based on the actual structure of the converter transformer, and a three-dimensional geometric model of the converter transformer is constructed based on the geometric parameters. The three-dimensional geometric model is meshed using finite element methods to obtain the three-dimensional finite element model based on the meshing results.

4. The method according to claim 3, characterized in that, The process of obtaining the initial inductance matrix of each winding based on the inductance simulation results includes: The inductance parameter export command is invoked, and the inductance simulation results are processed according to the inductance parameter export command to obtain the initial inductance matrix based on the processing results.

5. The method according to claim 1, characterized in that, Solving the inter-stage short-circuit fault model to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results includes: The inter-stage short-circuit fault model is solved in the time domain to obtain the inter-stage fault current of the converter transformer based on the solution results, and the inter-stage fault current is used as the fault simulation result.

6. A simulation device for short-circuit faults in the tap changer of a converter transformer, characterized in that, The converter transformer includes several windings, and the device includes: The inductance simulation module is used to perform inductance simulation on the three-dimensional finite element model of the converter transformer under the specified inter-stage short-circuit condition of the tap changer. The target inductance matrix generation module is used to obtain the initial inductance matrix of each winding based on the inductance simulation results, and convert the initial inductance matrix into the target inductance matrix based on the three-winding transformer model; The fault modeling module is used to determine the three-winding resistance parameters corresponding to the specified inter-stage short-circuit condition, and to construct the inter-stage short-circuit fault model of the converter transformer based on the target inductance matrix and the three-winding resistance parameters. The fault simulation module is used to solve the inter-stage short-circuit fault model, so as to obtain the fault simulation results of the converter transformer under the specified inter-stage short-circuit condition based on the solution results. The converter transformer includes several column cores. The initial inductance matrix is ​​converted into a target inductance matrix based on the three-winding transformer model. The target inductance matrix generation module includes: The first equivalent conversion subunit is used to obtain the grid-side current proportional coefficient and valve-side current proportional coefficient of each column core of the converter transformer, and convert the initial inductance matrix into the first equivalent inductance matrix corresponding to the three-winding transformer model according to the grid-side current proportional coefficient and valve-side current proportional coefficient. The second equivalent conversion subunit is used to determine the second equivalent inductance matrix of the three-winding transformer model based on the calculation relationship between the leakage inductance, excitation branch inductance and the three-winding voltage and three-winding current of the three-winding transformer model. The target inductance matrix sub-unit is used to determine the target inductance matrix based on the first equivalent inductance matrix and the second equivalent inductance matrix; The three-winding transformer model includes the primary side, the secondary side, and the fault port corresponding to the specified inter-stage short-circuit condition. The target inductance matrix includes the primary leakage inductance, secondary leakage inductance, equivalent leakage inductance of the branch where the fault port is located, and excitation branch inductance of the three-winding transformer model. The fault modeling module includes: The self-developed model subunit is used to construct a self-developed model based on the three-winding transformer model, and to construct the system external circuit corresponding to the self-developed model, wherein the system external circuit includes the short-circuit resistance corresponding to the specified inter-stage short-circuit condition; The three-winding resistor subunit is used to determine the first winding resistance on the primary side and the second winding resistance on the secondary side according to the self-developed model, to determine the third winding resistance of the fault port according to the impedance coupling relationship between the short-circuit resistance of the external circuit and the winding corresponding to the fault port, and to determine the three-winding resistance parameters according to the first winding resistance, the second winding resistance and the third winding resistance. The primary-side modeling subunit is used to determine the primary-side voltage equation based on the calculated relationship between the voltage and current on the primary side, the resistance of the first winding, the leakage inductance of the primary side, and the inductance of the excitation branch in the Laplace domain. The secondary side modeling subunit is used to determine the secondary side voltage equation based on the calculated relationship between the voltage and current on the secondary side, the resistance of the second winding, the leakage inductance of the secondary side, and the inductance of the excitation branch in the Laplace domain. The fault port modeling subunit is used to determine the fault port voltage equation based on the calculated relationship between the voltage and current of the fault port, the resistance of the third winding, the equivalent leakage inductance, and the inductance of the excitation branch in the Laplace domain. The model generation sub-unit is used to determine the inter-stage short-circuit fault model based on the primary side voltage equation, the secondary side voltage equation, and the fault port voltage equation.

7. A computer device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the simulation method for short-circuit faults of the tap changer of the converter transformer as described in any one of claims 1 to 5.

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