Simulation modeling method and device of long-distance superconducting direct current cable and terminal equipment

Abstract

The application discloses a simulation modeling method and device of a long-distance superconducting DC cable and terminal equipment, and relates to the technical field of superconducting DC cables. The method comprises the following steps: performing simulation modeling on the superconducting DC cable to obtain a superconducting DC cable simulation model; constructing a distributed equivalent circuit model of the long-distance superconducting DC cable based on the superconducting DC cable simulation model; constructing a distributed model of the superconducting DC cable according to the distributed equivalent circuit model; performing simulation modeling on the distributed model, and when superconducting quench occurs in a basic unit equivalent circuit, an initial value is given to the quench resistance of the corresponding basic unit equivalent circuit to obtain a to-be-processed quench resistance; the real values of the quench resistances of the basic unit equivalent circuits are determined through simulation iteration according to the to-be-processed quench resistances and a preset relationship curve; and the real values of the quench resistances of the basic unit equivalent circuits are fed back to superconducting DC cable operation and maintenance personnel, so that the operation and maintenance personnel can optimize the superconducting DC cable according to the real values of the quench resistances.

Description

Technical Field

[0001] This invention relates to the field of superconducting DC cable technology, and in particular to a simulation modeling method, apparatus and terminal equipment for long-distance superconducting DC cables. Background Technology

[0002] Superconducting power transmission technology boasts significant advantages such as large transmission capacity, low loss, and compact structure, making it a recent research hotspot in power transmission technology. Research on superconducting power transmission technology primarily focuses on the operational characteristics and fault mechanisms of superconducting DC cables when connected to long-distance DC transmission systems. Establishing a superconducting DC cable model that considers both quenching and distributed characteristics is crucial for analyzing the quenching characteristics of superconducting DC cables. The establishment of this model and the implementation of quenching analysis are of great significance for the design and operation management of superconducting DC cables. However, current simulation modeling methods for superconducting cables treat the cable as a single unit for quenching analysis, which presents significant challenges when performing quenching analysis on the entire cable when connected to long-distance DC transmission systems. Summary of the Invention

[0003] This invention provides a simulation modeling method, apparatus, and terminal equipment for long-distance superconducting DC cables, which can improve the efficiency of simulation modeling and quench analysis for long-distance superconducting DC cables.

[0004] An embodiment of the present invention provides a simulation modeling method, apparatus, and terminal equipment for long-distance superconducting DC cables, comprising:

[0005] A simulation model of a superconducting DC cable is obtained by performing a simulation model of the superconducting DC cable; wherein, the simulation model of the superconducting DC cable includes: a superconducting layer and a copper skeleton layer;

[0006] A distributed equivalent circuit model of a long-distance superconducting DC cable is constructed based on a simulation model of the superconducting DC cable. The distributed equivalent circuit model includes several basic unit equivalent circuits, each basic unit equivalent circuit corresponds to a superconducting DC cable segment, and each basic unit equivalent circuit includes the equivalent resistance of the corresponding superconducting DC cable segment. The equivalent resistance is composed of the superconducting layer resistance and the copper skeleton layer resistance connected in parallel.

[0007] A distributed model of the superconducting DC cable is constructed based on the aforementioned distributed equivalent circuit model.

[0008] The distributed model is simulated. When a superconducting DC cable fails in a basic unit equivalent circuit, an initial value is assigned to the failure resistance of the corresponding basic unit equivalent circuit to obtain the failure resistance to be processed; wherein, the failure resistance is the superconducting layer resistance at the time of failure.

[0009] The true value of the quench resistance of each basic unit's equivalent circuit is determined by simulation iteration based on each quench resistance to be processed and a preset relationship curve; wherein, the preset relationship curve is the relationship curve between quench resistance and quench heat.

[0010] The true value of the quench resistance of the equivalent circuit of each basic unit is fed back to the superconducting DC cable maintenance personnel so that they can optimize the superconducting DC cable based on the true value of the quench resistance.

[0011] Furthermore, the construction of the distributed equivalent circuit model of the long-distance superconducting DC cable based on the simulation model of the superconducting DC cable includes:

[0012] Based on the preset simulation accuracy, the superconducting DC cable simulation model is divided into several superconducting DC cable simulation sub-models; each superconducting DC cable simulation sub-model corresponds to a superconducting DC cable segment.

[0013] For each simulation sub-model of a superconducting DC cable, establish the corresponding basic unit equivalent circuit;

[0014] A distributed equivalent circuit model of a long-distance superconducting DC cable is constructed based on the equivalent circuits of each basic unit.

[0015] Furthermore, the simulation model of the superconducting DC cable also includes: liquid nitrogen, an electrical insulation layer, and a thermal insulation layer;

[0016] The copper skeleton layer is sequentially wrapped with a superconducting layer, an electrical insulation layer, liquid nitrogen, and a heat insulation layer.

[0017] Furthermore, the equivalent circuit of each basic unit also includes: a resistor and a capacitance to ground;

[0018] The equivalent resistance and reactance of the superconducting DC cable are connected in series, and the capacitance to ground is connected in parallel on both sides. Furthermore, after constructing a distributed equivalent circuit model of a long-distance superconducting DC cable based on a simulation model of the superconducting DC cable, the following is also included:

[0019] For each basic unit equivalent circuit, obtain the thermal parameters of the superconducting DC cable simulation model corresponding to each basic unit equivalent circuit; wherein, the thermal parameters include: the equivalent resistance of the superconducting DC cable, the heat absorbed by the superconducting tape, the heat capacity of each component of the superconducting tape, the liquid nitrogen coverage area, and the cable temperature.

[0020] Construct a thermal model of the equivalent circuit of the current basic unit based on the thermal parameters;

[0021] The construction of the distributed model of the superconducting DC cable based on the distributed equivalent circuit model includes:

[0022] A distributed model of the superconducting DC cable is constructed based on the equivalent circuits of each basic unit and the corresponding thermal models.

[0023] Furthermore, the simulation of the distributed model involves assigning an initial value to the quench resistance of the corresponding basic unit equivalent circuit when a superconducting DC cable fails in a basic unit equivalent circuit, thereby obtaining the quench resistance to be processed, including:

[0024] Set the simulation parameters for the distributed model of the superconducting DC cable; wherein, the simulation parameters include: critical current;

[0025] The distributed model is simulated based on the set simulation parameters;

[0026] When the real-time current of any basic unit equivalent circuit exceeds the critical current, the superconducting DC cable in the corresponding section of the current basic unit equivalent circuit loses its quench.

[0027] An initial value is assigned to the quench resistance of the current basic unit equivalent circuit to obtain the quench resistance to be processed.

[0028] Furthermore, after obtaining the quench resistance to be treated, the process also includes:

[0029] Obtain the length of the superconducting DC cable and the cross-sectional area of ​​the copper skeleton layer in the corresponding section of the equivalent circuit of the current basic unit;

[0030] Determine the quench temperature based on the thermal model of the current basic unit equivalent circuit;

[0031] The resistance of the copper skeleton layer during quench is calculated based on the quench temperature, the length of the superconducting DC cable corresponding to the section of the current basic unit equivalent circuit, and the cross-sectional area of ​​the copper skeleton layer.

[0032] Furthermore, the step of determining the true value of the quench resistance of each basic unit's equivalent circuit based on simulation iteration using each quench resistance to be processed and a preset relationship curve includes:

[0033] For each quench resistor to be processed, perform a quench resistor value update operation until the iteration error is less than the preset difference threshold, then take the quench resistor value to be processed under the current iteration as the true value of the quench resistor.

[0034] The quench resistance value update operation includes:

[0035] Based on the basic unit equivalent circuit containing the quench resistor to be processed, obtain the current curve of the quench resistor to be processed in the current iteration;

[0036] The quench thermal curve is determined based on the thermal model corresponding to the basic unit equivalent circuit containing the quench resistor to be processed.

[0037] The quench resistance value to be processed in the next iteration is determined based on the quench thermal curve and the preset relationship curve.

[0038] Substitute the quench resistance value to be processed in the next iteration into the equivalent circuit of the current basic unit to obtain the current curve corresponding to the quench resistance value to be processed in the next iteration.

[0039] The iteration error is calculated based on the current curve corresponding to the quench resistance value to be processed in the current iteration and the current curve corresponding to the quench resistance value to be processed in the next iteration.

[0040] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments;

[0041] One embodiment of the present invention provides a simulation modeling device for a long-distance superconducting DC cable, comprising: a distributed model modeling module, a simulation module, and a guidance optimization module;

[0042] The distributed modeling module is used to simulate and model the superconducting DC cable to obtain a simulation model of the superconducting DC cable. The simulation model includes a superconducting layer and a copper skeleton layer. A distributed equivalent circuit model of the long-distance superconducting DC cable is constructed based on the simulation model. This distributed equivalent circuit model includes several basic unit equivalent circuits, each corresponding to a segment of the superconducting DC cable. Each basic unit equivalent circuit includes an equivalent resistance for the corresponding segment, which is composed of the parallel connection of the superconducting layer resistance and the copper skeleton layer resistance. A distributed model of the superconducting DC cable is then constructed based on the distributed equivalent circuit model.

[0043] The simulation module is used to simulate the distributed model. When a superconducting DC cable fails in the equivalent circuit of a basic unit, an initial value is assigned to the failure resistance of the corresponding basic unit equivalent circuit to obtain the failure resistance to be processed; wherein, the failure resistance is the superconducting layer resistance at the time of failure; the true value of the failure resistance of each basic unit is determined by simulation iteration based on each failure resistance to be processed and a preset relationship curve; wherein, the preset relationship curve is the relationship curve between failure resistance and failure heat;

[0044] The guidance and optimization module is used to feed back the true value of the quench resistance of the equivalent circuit of each basic unit to the maintenance personnel of the superconducting DC cable, so that the maintenance personnel can optimize the superconducting DC cable according to the true value of the quench resistance.

[0045] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the simulation modeling method for a long-distance superconducting DC cable described in the above-described embodiment of the invention.

[0046] The following benefits can be obtained by implementing the present invention:

[0047] This invention provides a simulation modeling method, apparatus, and terminal equipment for long-distance superconducting DC cables. The method involves simulating and modeling the superconducting DC cable, then segmenting it into sections, constructing the basic unit equivalent circuit for each section, thus obtaining a distributed equivalent circuit model containing the basic unit equivalent circuits corresponding to several cable segments. A distributed model of the superconducting DC cable is then constructed based on this distributed equivalent circuit model. Simulation is performed on this distributed model, and when a quench occurs in any basic unit equivalent circuit, quench analysis is performed only on the corresponding basic unit equivalent circuit. This block-based analysis solves the problem of the difficulty in performing quench analysis on the entire cable when connected to a long-distance DC transmission system, improving the efficiency of quench analysis. It can also provide timely guidance for maintenance personnel to optimize and maintain the superconducting DC cable. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating a simulation modeling method for a long-distance superconducting DC cable according to an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram of a superconducting DC cable structure provided in an embodiment of the present invention.

[0050] Figure 3 This is a schematic diagram of a distributed equivalent circuit model of a long-distance superconducting DC cable provided in an embodiment of the present invention.

[0051] Figure 4 This is a diagram showing the relationship between quench heat and quench resistance transmission according to an embodiment of the present invention.

[0052] Figure 5 This is an embodiment of the R provided by the present invention. HTS -Q HTS Schematic diagram of the curve.

[0053] Figure 6 This is a schematic diagram of the structure of a simulation modeling device for a long-distance superconducting DC cable provided in an embodiment of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. 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.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0057] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0058] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0059] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0060] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0061] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0062] like Figure 1 The image shows a simulation modeling method for a long-distance superconducting DC cable provided by an embodiment of the present invention, comprising:

[0063] Step S1: Simulate and model the superconducting DC cable to obtain a simulation model of the superconducting DC cable; wherein, the simulation model of the superconducting DC cable includes: a superconducting layer and a copper skeleton layer;

[0064] Step S2: Construct a distributed equivalent circuit model of a long-distance superconducting DC cable based on the simulation model of the superconducting DC cable; wherein, the distributed equivalent circuit model includes several basic unit equivalent circuits, each basic unit equivalent circuit corresponds to a superconducting DC cable segment, and each basic unit equivalent circuit includes the equivalent resistance of the corresponding superconducting DC cable segment, the equivalent resistance being composed of the superconducting layer resistance and the copper skeleton layer resistance connected in parallel;

[0065] Step S3: Construct a distributed model of the superconducting DC cable based on the distributed equivalent circuit model;

[0066] Step S4: Simulate the distributed model. When a superconducting DC cable fails in a basic unit equivalent circuit, assign an initial value to the failure resistance of the corresponding basic unit equivalent circuit to obtain the failure resistance to be processed; wherein, the failure resistance is the superconducting layer resistance at the time of failure.

[0067] Step S5: Determine the true value of the quench resistance of each basic unit's equivalent circuit based on simulation iteration according to each quench resistance to be processed and the preset relationship curve; wherein, the preset relationship curve is the relationship curve between quench resistance and quench heat;

[0068] Step S6: Feed back the true value of the quench resistance of the equivalent circuit of each basic unit to the superconducting DC cable maintenance personnel so that the maintenance personnel can optimize the superconducting DC cable based on the true value of the quench resistance.

[0069] For step S1, the present invention employs the following... Figure 2 The single-pole cold-insulated superconducting DC cable structure shown is used for simulation modeling of superconducting DC cables.

[0070] In a preferred embodiment, the superconducting DC cable simulation model further includes: liquid nitrogen, an electrical insulation layer, and a heat insulation layer; the copper skeleton layer is sequentially wrapped with a superconducting layer, an electrical insulation layer, liquid nitrogen, and a heat insulation layer.

[0071] Specifically, such as Figure 2 As shown, the core of the single-pole cold-insulated superconducting DC cable is a copper skeleton layer, which is wrapped with a superconducting layer, an electrical insulation layer, liquid nitrogen and a heat insulation layer in sequence.

[0072] In a preferred embodiment, the step of constructing a distributed equivalent circuit model of a long-distance superconducting DC cable based on a superconducting DC cable simulation model includes: dividing the superconducting DC cable simulation model into several superconducting DC cable simulation sub-models based on a preset simulation accuracy; each superconducting DC cable simulation sub-model corresponds to a superconducting DC cable segment; establishing a corresponding basic unit equivalent circuit for each superconducting DC cable simulation sub-model; and constructing a distributed equivalent circuit model of the long-distance superconducting DC cable based on the basic unit equivalent circuits.

[0073] In a preferred embodiment, the equivalent circuit of each basic unit further includes: a resistor and a capacitance to ground; the equivalent resistance and reactance of the superconducting DC cable are connected in series, and the capacitance to ground is connected in parallel on both sides.

[0074] Specifically, after determining the hierarchical structure of the superconducting DC cable simulation model, based on the required accuracy and computational efficiency, the model is divided into several equally divided sub-models. Each sub-model corresponds to a segment of superconducting DC cable (i.e., the aforementioned superconducting DC cable section). It should be noted that because the division is equal, the lengths of the resulting superconducting DC cable segments should be equal. The preset simulation accuracy and the number of segments can be flexibly set according to the simulation analysis requirements to meet the needs of different simulation scenarios.

[0075] For step S2, as follows Figure 3 As shown, for each simulation sub-model of a superconducting DC cable, i.e., each superconducting DC cable segment, a corresponding basic unit equivalent circuit is established. This basic unit equivalent circuit is a dynamically coupled unit circuit. The equivalent circuit of each basic unit is as follows: Figure 3 As shown in the dashed box, the equivalent circuit of each basic unit consists of an equivalent resistance R. eq Series impedance L and equivalent resistance R eq It consists of parallel capacitors C; where the equivalent resistance R eq Partially composed of superconducting layer resistance R HTS and copper skeleton layer resistance R Cu They are connected in parallel. The inductance and capacitance parameters per kilometer are 1.45 mH / km and 0.076 μF / km, respectively. The resistance parameter of the equivalent resistance is determined by the superconducting layer resistance R.HTS and copper skeleton layer resistance R Cu Parallel connection is equivalent.

[0076] Based on the equivalent circuits of each basic unit, a simulation model of the superconducting DC cable can be obtained, and a distributed equivalent circuit model of the long-distance superconducting DC cable can be constructed.

[0077] In this invention, when performing superconductivity and quenching failure simulation analysis, the superconducting layer resistance is set to 0 when the superconducting DC cable is in a superconducting state. The superconducting layer resistance in the quenching failure state, i.e., the quenching resistance, will be calculated in subsequent steps.

[0078] For step S3, construct a distributed model of the superconducting DC cable based on the distributed equivalent circuit model.

[0079] In a preferred embodiment, after constructing a distributed equivalent circuit model of a long-distance superconducting DC cable based on a superconducting DC cable simulation model, the method further includes: for each basic unit equivalent circuit, obtaining the thermal parameters of the superconducting DC cable simulation model corresponding to each basic unit equivalent circuit; wherein, the thermal parameters include: the equivalent resistance of the superconducting DC cable, the heat absorbed by the superconducting tape, the heat capacity of each component of the superconducting tape, the liquid nitrogen coverage area, and the cable temperature; constructing a thermal model of the current basic unit equivalent circuit based on the thermal parameters; the construction of a distributed model of the superconducting DC cable based on the distributed equivalent circuit model includes: constructing a distributed model of the superconducting DC cable based on each basic unit equivalent circuit and the corresponding thermal model of each basic unit equivalent circuit.

[0080] Specifically, a thermal model is constructed for the equivalent circuit of each basic unit. This thermal model comprehensively considers the role of the cooling system after quench occurs, that is, it considers the thermal effects during the quench process.

[0081] When a superconducting DC cable loses its quench resistance, a certain amount of Joule heat will be generated. The heat transfer process is as follows:

[0082] Q total =Q HTS +Q S +Q LN +Q e

[0083] Among them, Q total Q represents the total Joule heat generated by the superconducting DC cable. HTS The heat absorbed by each component of the superconducting tape; Q S Q represents the heat absorbed by solid materials such as insulation. LN Q represents the heat removed by liquid nitrogen. e For heat transferred to the outside.

[0084] The principle of quench failure is mainly caused by the current flowing through the superconducting DC cable exceeding its critical current. Since the fault current duration is short, the heat exchange between the cable and the external environment during quench failure can be ignored. Therefore, the entire heat transfer process of the cable during quench failure can be approximated as an adiabatic process. Ignoring the heat absorbed by the electrical insulation layer and the thermal insulation layer, all the heat generated by the cable is absorbed by the superconducting tape and liquid nitrogen, leading to an increase in the temperature of the superconducting material in the superconducting layer. This temperature rise process corresponds to the thermal model of each basic unit and can be described as follows:

[0085] Q HTS =Q total -Q LN

[0086]

[0087]

[0088] Among them, R eq Q is the equivalent resistance of the superconducting DC cable. total Q represents the total Joule heat generated by the superconducting DC cable. HTS The heat absorbed by the superconducting tape; Q LN ΔT represents the heat carried away by the liquid nitrogen; ΔT represents the temperature difference between the liquid nitrogen and the superconducting material; h represents the heat transfer coefficient, which is a function of the temperature difference between the liquid nitrogen and the superconducting material; A represents the liquid nitrogen coverage area; T(t) represents the cable temperature; T0 represents the initial reference temperature, which is continuously updated during subsequent simulation iterations. In each iteration, the obtained T is used as the T0 for the next iteration. Initially, T0 is 77K.

[0089] By connecting all the basic unit equivalent circuits in series, a distributed equivalent circuit model is obtained. The distributed model of the superconducting DC cable is obtained by interacting the thermal model corresponding to each basic unit equivalent circuit with the dynamic parameters of the distributed equivalent circuit model.

[0090] For steps S4 and S5, in the system simulation, the above distributed model is connected to the long-distance DC transmission system. Each basic unit's equivalent circuit exchanges key parameters in real time with its corresponding thermal model, including critical current density, quench resistance, copper skeleton layer resistance, real-time current, and operating temperature.

[0091] In a preferred embodiment, the step of simulating the distributed model, and when a superconducting DC cable experiences quenching in a basic unit equivalent circuit, assigning an initial value to the quenching resistance of the corresponding basic unit equivalent circuit to obtain the quenching resistance to be processed, includes: setting simulation parameters for the distributed model of the superconducting DC cable; wherein the simulation parameters include a critical current; simulating the distributed model based on the set simulation parameters; when the real-time current of any basic unit equivalent circuit exceeds the critical current, the superconducting DC cable in the corresponding segment of the current basic unit equivalent circuit experiences quenching; assigning an initial value to the quenching resistance of the current basic unit equivalent circuit to obtain the quenching resistance to be processed.

[0092] The resistance of the copper skeleton layer is calculated in the thermal model corresponding to the equivalent circuit of the quench timeout basic unit. In a preferred embodiment, after obtaining the quench resistance to be processed, the method further includes: obtaining the length of the superconducting DC cable and the cross-sectional area of ​​the copper skeleton layer in the corresponding section of the current basic unit equivalent circuit; determining the quench temperature based on the thermal model of the current basic unit equivalent circuit; and calculating the resistance of the copper skeleton layer during quench time based on the quench temperature, the length of the superconducting DC cable in the corresponding section of the current basic unit equivalent circuit, and the cross-sectional area of ​​the copper skeleton layer.

[0093] Specifically, during the simulation, simulation parameters are first set, including the critical current and initial temperature. When the real-time current of any basic unit exceeds the critical current, it is determined that the superconducting DC cable in the corresponding section of the equivalent circuit of the current basic unit has lost quench. At this time, the superconducting layer resistance of the equivalent circuit of the current basic unit is the quench resistance, and an initial value R is assigned to this quench resistance. i (i = 0).

[0094] Obtain the superconducting DC cable length and copper skeleton layer cross-sectional area of ​​the superconducting DC cable section corresponding to the current basic unit equivalent circuit. Determine the quench temperature T based on the thermal model of the basic unit equivalent circuit.

[0095] Preferably, after obtaining the current quench temperature, it is necessary to immediately update the temperature-dependent parameters, mainly including the critical current density and the resistivity of copper.

[0096] The dependence of the critical current density on temperature can be described as follows:

[0097]

[0098] Among them, T r The initial reference temperature is 77K; T c The critical temperature is 92K; the coefficient k = T c -T r In this invention, a is set to 1.5; J cThis is the initial critical current density under reference temperature conditions.

[0099] The resistance of the copper skeleton layer in a superconducting DC cable is mainly determined by the resistivity of copper at low temperatures and the dimensions of the cable itself. The resistivity of copper at low temperatures is shown below:

[0100] ρ Cu = (0.0084T - 0.4603) × 10 -8 70K≤T<250K

[0101] Based on the cross-sectional area S of the copper skeleton layer, the length l of the superconducting DC cable, and the resistivity ρ of copper at low temperature Cu The resistance R of the copper skeleton layer can be calculated using the formula. Cu :

[0102]

[0103] Furthermore, the true value of the quench resistance corresponding to the superconducting layer resistance under quench conditions is calculated.

[0104] During the quench loss period, the superconducting DC cable is approximately considered to be in an adiabatic state. All the heat generated by the quench loss is absorbed by the superconducting layer and liquid nitrogen, with the heat absorbed by the superconducting layer contributing to the accumulation of heat generated by the cable's own temperature rise. Combining the dependence of the critical current density on temperature, it is known that the critical current density is related to temperature. Furthermore, the following superconducting EJ relationship shows that the quench resistance is closely related to the change in critical current density. The superconducting EJ relationship is shown below:

[0105]

[0106] Where E0 is the critical electric field strength.

[0107] Based on the above relationship analysis, we can establish the following: Figure 4 The superheat Q shown HTS Cable quench temperature T, critical current density J C and overcurrent resistance R HTS The transfer relationship between them. According to this transfer relationship, during the quench temperature rise process, the quench resistance R... HTS Only with its own loss of superheat Q HTS It is related to, and therefore, independent of, the waveform, frequency, and amplitude of the current flowing through the current limiter. Therefore, whether in an AC or DC system, the quench resistance-quench heat curve (i.e., the preset relationship curve, which can be simplified as R...) HTS -Q HTS The curves (referring to the quench curve and its relationship) remain the same for a short period after the superconducting DC cable loses its quench. A fixed quench heat value corresponds to a fixed quench resistance value; that is, the quench resistance value can be determined from the quench heat value based on this relationship curve. For example... Figure 5The figure shown is the R provided by the present invention. HTS -Q HTS Schematic diagram of the curve.

[0108] In a preferred embodiment, the step of determining the true value of the quench resistance of each basic unit equivalent circuit based on simulation iteration of each quench resistance to be processed and a preset relationship curve includes: for each quench resistance to be processed, performing a quench resistance value update operation until the iteration error is less than a preset difference threshold, and then taking the quench resistance value to be processed under the current iteration as the true value of the quench resistance.

[0109] The quench resistance value update operation includes: obtaining the current curve of the quench resistance to be processed in the current iteration based on the basic unit equivalent circuit containing the quench resistance to be processed; determining the quench thermal curve based on the thermal model corresponding to the basic unit equivalent circuit containing the quench resistance to be processed; determining the quench resistance value to be processed in the next iteration based on the quench thermal curve and a preset relationship curve; substituting the quench resistance value to be processed in the next iteration into the current basic unit equivalent circuit to obtain the current curve corresponding to the quench resistance value to be processed in the next iteration; and calculating the iteration error based on the current curve corresponding to the quench resistance value to be processed in the current iteration and the current curve corresponding to the quench resistance value to be processed in the next iteration.

[0110] Specifically, an initial value R is assigned to the quench resistance. i After (i=0), the superconducting layer resistance value in the equivalent circuit of the corresponding basic unit is replaced by R. i The quench resistance after value replacement is taken as the quench resistance to be processed. After value replacement, a quench resistance value update operation is performed until the iteration error is less than a preset difference threshold. Then, the quench resistance value to be processed under the current iteration is taken as the true value of the quench resistance. When performing the quench resistance value update operation, the quench resistance value to be processed is R. i Simulations were performed using the basic unit to obtain the superconducting layer fault current variation curve It under the quench resistance to be treated. Simultaneously, the quench heat Q was calculated using the thermal model corresponding to the equivalent circuit of the basic unit. HTS The superheat curve Q was obtained. HTS -t. Based on the calculated superheat Q HTS Check R HTS -Q HTS The curve yields the quench resistance value R to be processed in the next iteration. HTS and the change of the quench resistance to be treated over time R HTS -t curve. Preferably, according to R HTS and R Cu The new parallel equivalent resistance R can be calculated. eqThe quench resistance value to be processed in the next iteration is substituted into the equivalent circuit of the current basic unit to obtain the current curve corresponding to the quench resistance value in the next iteration. The degree of overlap between the current curve corresponding to the quench resistance value in the current iteration and the current curve corresponding to the quench resistance value in the next iteration is calculated. This degree of overlap is the iteration error, which can be judged by calculating the Euclidean distance between the two curves. The formula for calculating the Euclidean distance is as follows:

[0111]

[0112] Where i is the iteration number; j is the sampling point; I i+1 I is the current in the (i+1)th iteration; i Let be the current in the i-th iteration.

[0113] When the Euclidean distance d between the fault current curves obtained from the two most recent iterations is less than δ (a preset difference threshold, in this invention δ = 1 to 6), the iteration is considered to have converged. At this time, the quench resistance value to be processed under the current iteration is taken as the true value of the quench resistance. If the condition is not met, the above quench resistance value update operation is repeated until d is less than δ.

[0114] For step S6, after obtaining the true value of the quench resistance, the parallel equivalent resistance can be obtained by combining it with the corresponding resistance value of the copper skeleton layer under the quench state. The true value of the quench resistance corresponding to the superconducting layer resistance under the quench state, the resistance value of the copper skeleton layer, and the current curve and quench thermal curve obtained during the simulation are fed back to the superconducting DC cable maintenance personnel. The superconducting DC cable maintenance personnel can optimize the design and safe operation and maintenance of the superconducting DC cable based on the feedback parameters, and promptly guide the maintenance personnel to optimize the maintenance of the superconducting DC cable.

[0115] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments.

[0116] like Figure 6 As shown, an embodiment of the present invention provides a simulation modeling device for long-distance superconducting DC cables, including: a distributed model modeling module, a simulation module, and a guidance optimization module;

[0117] The distributed modeling module is used to simulate and model the superconducting DC cable to obtain a simulation model of the superconducting DC cable. The simulation model includes a superconducting layer and a copper skeleton layer. A distributed equivalent circuit model of the long-distance superconducting DC cable is constructed based on the simulation model. This distributed equivalent circuit model includes several basic unit equivalent circuits, each corresponding to a segment of the superconducting DC cable. Each basic unit equivalent circuit includes an equivalent resistance for the corresponding segment, which is composed of the parallel connection of the superconducting layer resistance and the copper skeleton layer resistance. A distributed model of the superconducting DC cable is then constructed based on the distributed equivalent circuit model.

[0118] The simulation module is used to simulate the distributed model. When a superconducting DC cable fails in a basic unit equivalent circuit, an initial value is assigned to the failure resistance of the corresponding basic unit equivalent circuit to obtain the failure resistance to be processed; wherein, the failure resistance is the superconducting layer resistance at the time of failure; the true value of the failure resistance of each basic unit equivalent circuit is determined by simulation iteration based on each failure resistance to be processed and a preset relationship curve; wherein, the preset relationship curve is the relationship curve between failure resistance and failure heat;

[0119] The guidance and optimization module is used to feed back the true value of the quench resistance of the equivalent circuit of each basic unit to the maintenance personnel of the superconducting DC cable, so that the maintenance personnel can optimize the superconducting DC cable according to the true value of the quench resistance.

[0120] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0121] Those skilled in the art will clearly understand that, for convenience and brevity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0122] Based on the above method embodiments, the present invention provides corresponding terminal device embodiments.

[0123] One embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements a simulation modeling method for a long-distance superconducting DC cable as described in any one of the present invention.

[0124] The terminal device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0125] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0126] The memory can be used to store the computer program. The processor implements various functions of the terminal device by running or executing the computer program stored in the memory and calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart memory card (SMC), secure digital card (SD), flash memory card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0127] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method of simulation modeling of a long distance superconducting DC cable, characterized by, The application relates to a method for simulating a long-distance superconducting direct-current cable. The method comprises the following steps: a superconducting direct-current cable simulation model is established by simulating and modeling the superconducting direct-current cable, wherein the superconducting direct-current cable simulation model comprises a superconducting layer and a copper framework layer; a distributed equivalent circuit model of the long-distance superconducting direct-current cable is established based on the superconducting direct-current cable simulation model, wherein the distributed equivalent circuit model comprises a plurality of basic unit equivalent circuits, each basic unit equivalent circuit corresponds to a superconducting direct-current cable section, and each basic unit equivalent circuit comprises an equivalent resistance of the corresponding superconducting direct-current cable section, wherein the equivalent resistance is composed of the parallel connection of the superconducting layer resistance and the copper framework layer resistance; a distributed model of the superconducting direct-current cable is established according to the distributed equivalent circuit model; when a superconducting direct-current cable quench occurs in a basic unit equivalent circuit, an initial value is given to a quench resistance of the corresponding basic unit equivalent circuit to obtain a to-be-processed quench resistance, wherein the quench resistance is the superconducting layer resistance when the quench occurs; the real value of the quench resistance of each basic unit equivalent circuit is determined according to each to-be-processed quench resistance and a preset relationship curve, wherein the preset relationship curve is a relationship curve of the quench resistance and the quench heat; the real value of the quench resistance of each basic unit equivalent circuit is fed back to a superconducting direct-current cable operation and maintenance personnel, so that the operation and maintenance personnel optimize the superconducting direct-current cable according to the real value of the quench resistance; wherein, after establishing the distributed equivalent circuit model of the long-distance superconducting direct-current cable based on the superconducting direct-current cable simulation model, the method further comprises the following steps: for each basic unit equivalent circuit, the thermal parameters of the superconducting direct-current cable simulation model corresponding to each basic unit equivalent circuit are obtained; wherein the thermal parameters comprise the equivalent resistance of the superconducting direct-current cable, the heat absorbed by the superconducting tape, the heat capacity of each component of the superconducting tape, the liquid nitrogen coverage area and the cable temperature; a thermal model of the current basic unit equivalent circuit is established according to the thermal parameters; the distributed model of the superconducting direct-current cable is established according to the distributed equivalent circuit model, comprising: the distributed model of the superconducting direct-current cable is established according to each basic unit equivalent circuit and the thermal model corresponding to each basic unit equivalent circuit; after obtaining the to-be-processed quench resistance, the method further comprises the following steps: the length of the superconducting direct-current cable and the cross-sectional area of the copper framework layer of the section corresponding to the current basic unit equivalent circuit are obtained; the quench temperature is determined according to the thermal model of the current basic unit equivalent circuit; the resistance of the copper framework layer when the quench occurs is calculated according to the quench temperature, the length of the superconducting direct-current cable of the section corresponding to the current basic unit equivalent circuit and the cross-sectional area of the copper framework layer; after determining the quench temperature according to the thermal model of the current basic unit equivalent circuit, the temperature-dependent critical current density is updated; wherein, is an initial reference temperature; is a critical temperature; coefficient ; is 1.5; is an initial critical current density under a reference temperature condition; T is a quench temperature; is an initial reference temperature under a preset critical current density constant value.

2. A method of simulation modeling of a long distance superconducting DC cable as claimed in claim 1, characterized in that, the temperature-dependent critical current density is as follows: the distributed equivalent circuit model of the long-distance superconducting direct-current cable is established based on the superconducting direct-current cable simulation model, comprising: the superconducting direct-current cable simulation model is divided into a plurality of superconducting direct-current cable simulation sub-models based on a preset simulation precision; each superconducting direct-current cable simulation sub-model corresponds to a superconducting direct-current cable section; for each superconducting direct-current cable simulation sub-model, the corresponding basic unit equivalent circuit is established; The distributed equivalent circuit model of the long-distance superconducting DC cable is constructed according to equivalent circuits of the basic units.

3. A method of simulation modeling of a long distance superconducting DC cable according to claim 2, characterized in that, The superconducting DC cable simulation model further comprises liquid nitrogen, an electrical insulation layer and a thermal insulation layer. The copper framework layer is sequentially wrapped with the superconducting layer, the electrical insulation layer, the liquid nitrogen and the thermal insulation layer.

4. A method of simulation modeling of a long distance superconducting DC cable according to claim 3, characterized in that, Each of the equivalent circuits of the basic units further comprises an electrical reactance and a ground capacitance. The equivalent resistance and the electrical reactance of the superconducting DC cable are connected in series, and the ground capacitances are connected in parallel on both sides.

5. A method of simulation modeling of a long distance superconducting DC cable according to claim 4, characterized in that, The simulation of the distributed model is performed, when the superconducting DC cable loses superconductivity in an equivalent circuit of a basic unit, an initial value is assigned to the superconductivity loss resistance of the corresponding equivalent circuit of the basic unit, and a to-be-processed superconductivity loss resistance is obtained, comprising: Simulation parameters of the distributed model of the superconducting DC cable are set, wherein the simulation parameters comprise a critical current; The distributed model is simulated based on the set simulation parameters; When the real-time current of any equivalent circuit of a basic unit exceeds the critical current, the superconducting DC cable in the corresponding section of the current equivalent circuit of the basic unit loses superconductivity; An initial value is assigned to the superconductivity loss resistance of the current equivalent circuit of the basic unit, and a to-be-processed superconductivity loss resistance is obtained.

6. A method of simulation modeling of a long distance superconducting DC cable according to claim 5, characterized in that, The real value of the superconductivity loss resistance of each equivalent circuit of the basic unit is determined according to each to-be-processed superconductivity loss resistance and a preset relationship curve, comprising: For each to-be-processed superconductivity loss resistance, a superconductivity loss resistance value updating operation is performed until the iteration error is less than a preset difference threshold, and the to-be-processed superconductivity loss resistance value at the current iteration is taken as the real value of the superconductivity loss resistance; The superconductivity loss resistance value updating operation comprises: According to the equivalent circuit of the basic unit containing the to-be-processed superconductivity loss resistance, the current curve of the to-be-processed superconductivity loss resistance at the current iteration is obtained; According to the thermal model corresponding to the equivalent circuit of the basic unit containing the to-be-processed superconductivity loss resistance, the superconductivity heat curve is determined; The to-be-processed superconductivity loss resistance value of the next iteration is determined according to the superconductivity heat curve and the preset relationship curve; The to-be-processed superconductivity loss resistance value of the next iteration is substituted into the current equivalent circuit of the basic unit, and the current curve corresponding to the to-be-processed superconductivity loss resistance value of the next iteration is obtained; The iteration error is calculated according to the current curve corresponding to the to-be-processed superconductivity loss resistance value at the current iteration and the current curve corresponding to the to-be-processed superconductivity loss resistance value at the next iteration.

7. A simulation modeling device for long distance superconducting DC cables, characterized by A simulation modeling method for a long-distance superconducting DC cable according to any one of claims 1-6, comprising a distributed model modeling module, a simulation module and a guidance optimization module; The distributed model modeling module is used for simulating modeling of the superconducting DC cable to obtain a superconducting DC cable simulation model; wherein the superconducting DC cable simulation model comprises a superconducting layer and a copper framework layer; a distributed equivalent circuit model of the long-distance superconducting DC cable is constructed based on the superconducting DC cable simulation model; wherein the distributed equivalent circuit model comprises a plurality of basic unit equivalent circuits, each basic unit equivalent circuit corresponds to a superconducting DC cable section, and each basic unit equivalent circuit comprises an equivalent resistance of the corresponding superconducting DC cable section, the equivalent resistance being composed of the parallel connection of the superconducting layer resistance and the copper framework layer resistance; a distributed model of the superconducting DC cable is constructed according to the distributed equivalent circuit model; The simulation module is configured to simulate the distributed model, assign an initial value to a quench resistance of a corresponding basic unit equivalent circuit when a superconducting DC cable of the basic unit equivalent circuit quenches, and obtain a to-be-processed quench resistance; the quench resistance is a superconducting layer resistance when the superconducting DC cable quenches; and the real value of the quench resistance of each basic unit equivalent circuit is determined according to each to-be-processed quench resistance and a preset relationship curve; the preset relationship curve is a relationship curve between the quench resistance and quench heat. The guidance optimization module is configured to feed back the real value of the quench resistance of each basic unit equivalent circuit to a superconducting DC cable operation and maintenance personnel, so that the operation and maintenance personnel optimize the superconducting DC cable according to the real value of the quench resistance.

8. A terminal device, comprising: A computer program product including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the computer program being executed by the processor to implement the simulation modeling method of the long-distance superconducting DC cable according to any one of claims 1 to 6.

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