A superconducting cable modeling method and device for electromagnetic transient simulation

Abstract

The invention discloses a modeling method for a superconducting cable for electromagnetic transient simulation, which is characterized by comprising: establishing a superconducting cable multi-state circuit simulation model; establishing a simplified simulation model of a power grid or superconducting cable fault by simplifying the superconducting cable multi-state circuit simulation model according to the influence of a power grid fault on the electrical quantity of the superconducting cable; using electromagnetic transient simulation software and the simplified simulation model of the power grid or superconducting cable fault to build a superconducting cable model for electromagnetic transient simulation, aiming at the needs of power grid fault analysis or superconducting cable relay protection, and the problems of traditional superconducting cable simulation models in terms of calculation efficiency, calculation accuracy of key electrical quantities, and continuous switching of multiple operating states, according to the requirements of power grid fault analysis, the superconducting cable circuit simulation model is simplified and integrated into the electromagnetic transient simulation model to meet the requirements of power grid fault simulation analysis.

Description

Technical Field

[0001] The present application relates to the field of digital simulation methods for superconducting cable superconducting state, quenched transient state and complete quenched state, and specifically to a modeling method for superconducting cables for electromagnetic transient simulation, and also to a modeling device for superconducting cables for electromagnetic transient simulation. Background Art

[0002] With the increasing demand for energy and the dual constraints of resources and the environment, clean substitution and electric energy substitution will become the main direction of the new energy revolution. In order to adapt to the trend of large-scale grid connection of new energy and the increasing proportion of electricity consumption in terminal energy, the research on efficient, safe and environmentally friendly power transmission technology is becoming increasingly active. As one of the technologies with the most development potential in the 21st century, superconducting technology is being actively promoted in the fields of electricity, motors, automobiles, aerospace, high-energy physics and rail transportation. Among them, superconducting power application technology is an early research field, and it is also the most mature and closest direction of large-scale application of superconducting technology. Before superconducting cables are applied to actual power grids, large-scale simulation and experiments are required. The existing digital simulation and modeling methods include steady-state digital simulation models and transient simulation models of superconducting cables.

[0003] The conductor layer of a high-temperature superconducting cable is wound with a high-temperature superconducting tape. The currents of the superconducting layer and the shielding layer are equal in magnitude and opposite in direction. Usually, the operating current of the superconducting tape is less than its critical current. At this time, the resistance value is very small and can be considered to be almost zero. The steady-state model of the superconducting cable can be used to simulate the operating characteristics of the superconducting cable. During normal operation, the current flowing through the superconducting cable is mainly determined by the self-inductance of the superconducting layer, the mutual inductance of the superconducting layer, the self-inductance of the shielding layer, the mutual inductance of the shielding layer, and the mutual inductance between the superconducting layer and the shielding layer. The factors affecting the self-inductance and mutual inductance are the winding radius, winding angle, winding direction, and number of windings of the superconducting tape. Studies have shown that when the ratio of the current flowing through the superconducting cable to the critical current of the superconducting cable is close to 1, the higher the current sharing degree of the superconducting cable, the smaller the loss during normal operation. Studies have found that by optimizing the winding radius, winding angle, winding direction, and winding number of the superconducting tape, the size of the self-inductance and mutual inductance of each layer can be changed, so that the current of each layer is evenly distributed.

[0004] When the operating current is greater than its critical current, the superconducting tape will experience an instantaneous quench, generating a quench resistor, and causing the current to be redistributed in the superconducting cable. At this time, the transient simulation model of the superconducting cable with resistance needs to be considered. The quench resistor of the superconducting tape is a binary function of current density and temperature, and its variation law is relatively complex. Generally, the change in temperature affects the critical current of the tape itself, while the change in the critical current affects the current density of the tape. The current density and the critical current affect the quench resistor, and the accumulation of heat in the quench resistor brings about temperature changes. In view of this complex change, the time discretization method is used to establish a mathematical model of the equivalent circuit and a heat conduction model of the high-temperature superconducting cable based on magnetothermal coupling analysis. When the temperature of the superconducting cable is greater than the critical temperature, the current of the cable mainly flows through the copper skeleton and the copper stabilization layer of the superconducting tape. Since the cross-sectional area of ​​the copper skeleton is much larger than that of the superconducting tape, the resistance of the copper skeleton is one order of magnitude smaller than the quench resistor of the conductor layer, and most of the fault current is shunted through the copper skeleton.

[0005] Existing cable models are divided into two categories: a steady-state model that only considers the effects of self-inductance and mutual inductance in the superconducting state; and a transient model that considers the copper skeleton resistance, stable layer resistance, quench resistance, interlayer self-inductance and mutual inductance when a fault occurs. However, when a superconducting cable is impacted by a fault current, the superconducting cable is also in a superconducting state for a period of time within a power frequency cycle. However, the above two models cannot fully describe this phenomenon. For the power grid fault analysis model containing superconducting cables, the above two models cannot reflect the phenomenon of continuous changes in multiple states of superconducting cables, including superconducting state, quench transient state and complete quench, which is not conducive to the research on superconducting cable relay protection and quench protection algorithm. Summary of the invention

[0006] The present application provides a modeling method of a superconducting cable for electromagnetic transient simulation, which is used to meet the needs of power grid fault simulation analysis.

[0007] The present application provides a modeling method for a superconducting cable for electromagnetic transient simulation, comprising:

[0008] Establish a multi-state circuit simulation model for superconducting cables;

[0009] According to the influence of the power grid fault on the electrical quantity of the superconducting cable, a simplified simulation model of the power grid or superconducting cable fault is established by simplifying the superconducting cable multi-state circuit simulation model;

[0010] A superconducting cable model for electromagnetic transient simulation is constructed by using electromagnetic transient simulation software and a simplified simulation model of the power grid or superconducting cable fault.

[0011] Preferably, the superconducting cable multi-state circuit simulation model, wherein the superconducting cable multi-state includes:

[0012] The normal operating superconducting state, superconducting transient quenching state and superconducting complete quenching state of superconducting cables in power grid operation.

[0013] Preferably, the superconducting cable multi-state circuit simulation model is used to simulate the quenching process of the superconducting cable from a superconducting normal operating state to a superconducting complete quenching state.

[0014] Preferably, the influence of the power grid fault on the electrical quantity of the superconducting cable includes:

[0015] The impact of faults in the power grid on the electrical quantities of the superconducting cables; and

[0016] The impact of faults at different locations in the superconducting cable on various electrical quantities at different locations in the power grid.

[0017] Preferably, establishing a simplified simulation model of a power grid or superconducting cable fault by simplifying the superconducting cable multi-state circuit simulation model comprises:

[0018] The copper skeleton branch and the supporting layer branch, the controllable diode branch and the diode control logic, and the superconducting layer resistance in the superconducting cable multi-state circuit simulation model are ignored, and a simplified simulation model of a power grid or superconducting cable fault is established.

[0019] Preferably, it also includes:

[0020] Multiple simplified simulation models of power grid or superconducting cable faults are connected in series to form a superconducting cable and power grid fault simulation model that can simulate faults at different positions of the superconducting cable.

[0021] Preferably, the use of electromagnetic transient simulation software and the simplified simulation model of the power grid or superconducting cable fault to build a superconducting cable model for electromagnetic transient simulation includes:

[0022] The multi-winding coil mutual inductance module in MATLAB\SIMULINK electromagnetic transient simulation software and other power grid component libraries can be used to build a superconducting cable model for electromagnetic transient simulation.

[0023] Preferably, the superconducting cable model for electromagnetic transient simulation is used to simulate faults at different locations and of various fault types.

[0024] The present application also provides a modeling device for a superconducting cable for electromagnetic transient simulation, which is characterized by comprising:

[0025] A superconducting cable multi-state circuit simulation model building unit, used for building a superconducting cable multi-state circuit simulation model;

[0026] A simplified simulation model establishment unit for a power grid or superconducting cable fault, used to establish a simplified simulation model for a power grid or superconducting cable fault by simplifying the superconducting cable multi-state circuit simulation model according to the influence of the power grid fault on the electrical quantity of the superconducting cable;

[0027] The superconducting cable model building unit for electromagnetic transient simulation is used to build a superconducting cable model for electromagnetic transient simulation by using electromagnetic transient simulation software and a simplified simulation model of the power grid or superconducting cable fault.

[0028] Preferably, it also includes:

[0029] The superconducting cable and power grid fault simulation model establishment subunit is used to connect multiple simplified simulation models of power grid or superconducting cable faults in series to form a superconducting cable and power grid fault simulation model that can simulate faults at different positions of the superconducting cable.

[0030] The present application provides a modeling method for superconducting cables for electromagnetic transient simulation. Aiming at the needs of power grid fault analysis or superconducting cable relay protection, and the problems of traditional superconducting cable simulation models in terms of calculation efficiency, calculation accuracy of key electrical quantities, and continuous switching of multiple operating states, the superconducting cable circuit simulation model is simplified according to the requirements of power grid fault analysis and integrated into the electromagnetic transient simulation model to meet the requirements of power grid fault simulation analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flow chart of a method for modeling a superconducting cable for electromagnetic transient simulation provided in an embodiment of the present application;

[0032] Figure 2 It is a circuit model that reflects the continuous conversion between the steady state and the quench transient state of the superconducting cable involved in the embodiment of the present application;

[0033] Figure 3 is an internal fault diagram of a superconducting cable involved in an embodiment of the present application;

[0034] Figure 4 It is a simplified simulation model for power grid or superconducting cable faults involved in the embodiments of the present application;

[0035] Figure 5 It is a superconducting cable model for electromagnetic transient simulation built by MATLAB\SIMULINK involved in the embodiment of the present application;

[0036] Figure 6 This is a schematic diagram of a modeling device for a superconducting cable for electromagnetic transient simulation provided by the present application. DETAILED DESCRIPTION

[0037] Many specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.

[0038] Figure 1 A schematic diagram of a flow chart of a modeling method for a superconducting cable for electromagnetic transient simulation provided in an embodiment of the present application is shown below in conjunction with Figure 1 The modeling method provided in this application is described in detail.

[0039] Step S101, establishing a superconducting cable multi-state circuit simulation model.

[0040] Superconducting cables experience normal operating superconducting states, superconducting quenching states, and superconducting complete quenching states during grid operation. During the superconducting quenching transient state, the resistance of the superconducting layer does not increase linearly, but oscillates and gradually increases. During the oscillation process, there will also be an intermittent angle, that is, the superconducting layer resistance will also appear in a superconducting state of 0. The multi-state circuit simulation model of superconducting cables is used to simulate the quenching process of superconducting cables from the normal operating superconducting state to the superconducting complete quenching state. In order to accurately simulate the superconducting quenching transient state in which superconducting cables alternate between the normal operating superconducting state, the superconducting complete quenching state, and the superconducting alternating state, a multi-state circuit simulation model of superconducting cables needs to be established. The simulation model is as follows: Figure 2 shown.

[0041] In the model, controllable switch devices are introduced into the copper skeleton branch and the support layer branch of each superconducting layer to control the opening and closing of the branch. The opening and closing logic is as follows: Figure 2 As shown in b), when a superconducting layer enters the quench state, the copper skeleton layer and the support layer branch are connected to simulate the quench transient process. When no superconducting layer is in the quench state, the copper skeleton layer and all support layer branches are disconnected to simulate the superconducting state. The multi-state circuit simulation model of the superconducting cable is shown in formula (1).

[0042]

[0043] in, It is a matrix composed of the self-inductance and mutual inductance of the superconducting cable copper skeleton, each supporting layer, each superconducting layer and each shield, which is determined by factors such as the copper skeleton size, superconducting wire and shielding layer size, and winding angle.

[0044] [R]=diag[R 11 ,R 12 ,R 13 ,R 22 ,R 23 ...R i2 ,R i3 ,...R n2,R n3 ] is a diagonal matrix whose elements are the resistances of each branch in the model. 11 , R i2 is the resistance of the copper skeleton and the supporting layer. i3 is the resistance of the superconducting layer or shielding layer. When the superconducting cable is in steady state operation, its value is 0. During the quenching process, a large amount of current flows into the copper skeleton and the supporting layer, causing the temperature of the superconducting cable to rise, the quenching current threshold to decrease, and a larger resistance to appear. The quenching current threshold of the superconducting tape at a higher temperature is shown in formula (2).

[0045]

[0046] Among them, I c0 T is the quench current threshold of the superconducting tape at the normal operating liquid nitrogen temperature. c T is the temperature at which the strip loses its supercritical state. op Liquid nitrogen temperature for normal strip operation.

[0047] The quench resistance value of the superconducting tape is shown in formula (3).

[0048]

[0049] E0 is the quench electric field strength parameter, L and N are the length and number of superconducting tapes respectively.

[0050] i=[i 11 ,i 12 ,i 13 ,i 22 ,i 23 ...i i2 ,i i3 ,...i n2 ,i n3 ] T is the current of each branch of the model.

[0051] S=[S 11 ,S 12 ,1,S 21 ,1...S i1 ,1...S n1 ,1], is the quench branch control switch function, and its variable state value is determined by the superconducting layer branch current i i3 Determine, as shown in formula (4).

[0052]

[0053] Step S102, according to the influence of the power grid fault on the electrical quantity of the superconducting cable, by simplifying the superconducting cable multi-state circuit simulation model, a simplified simulation model of the power grid or superconducting cable fault is established.

[0054] In the simulation model of a power grid containing superconducting cables, two aspects must be considered. On the one hand, the impact of faults in the power grid on the electrical quantities of the superconducting cables. On the other hand, the impact of faults at different locations in the superconducting cables on various electrical quantities at different locations in the power grid.

[0055] The fault occurs at different fault locations such as Figure 3 shown. Figure 3 a) in the figure indicates that a fault occurs inside the transformer connected to the superconducting cable in the power grid, such as K1 and K2, or a fault occurs in other parts of the power grid, such as K3. Figure 3 b) indicates that the superconducting layer and shielding layer of the superconducting cable fail, K1 and K2 respectively indicate that one layer and multiple layers of superconducting layers fail to the ground, and K3 and K4 respectively indicate that one layer and multiple layers of shielding layers fail to the ground.

[0056] neglect Figure 2 The copper skeleton branch and supporting layer branch, the controllable diode branch and diode control logic, and the superconducting layer resistance are combined to form a simplified simulation model of the superconducting cable. Multiple simplified simulation models of power grid or superconducting cable faults are connected in series to form a superconducting cable and power grid fault simulation model that can simulate faults at different locations of the superconducting cable, such as Figure 4 Point K1 is an internal fault of the superconducting cable, and points K2 and K3 are faults at the ends of the superconducting cable.

[0057] Step S103, using electromagnetic transient simulation software and the simplified simulation model of the power grid or superconducting cable fault, to build a superconducting cable model for electromagnetic transient simulation,

[0058] The multi-winding coil mutual inductance module in MATLAB\SIMULINK electromagnetic transient simulation software and other power grid component libraries can be used to build a superconducting cable model for electromagnetic transient simulation, such as Figure 5 , used to simulate faults at different locations and of various fault types.

[0059] Corresponding to the modeling method provided in the present application, the present application also provides a modeling device 600 for a superconducting cable for electromagnetic transient simulation, such as Figure 6 As shown, it is characterized by comprising:

[0060] A superconducting cable multi-state circuit simulation model establishing unit 610 is used to establish a superconducting cable multi-state circuit simulation model;

[0061] A simplified simulation model establishment unit 620 for a power grid or superconducting cable fault is used to establish a simplified simulation model for a power grid or superconducting cable fault by simplifying the superconducting cable multi-state circuit simulation model according to the influence of the power grid fault on the electrical quantity of the superconducting cable;

[0062] The superconducting cable model building unit 630 for electromagnetic transient simulation is used to build a superconducting cable model for electromagnetic transient simulation by using electromagnetic transient simulation software and the simplified simulation model of the power grid or superconducting cable fault.

[0063] The modeling device further comprises:

[0064] The superconducting cable and power grid fault simulation model establishment subunit is used to connect multiple simplified simulation models of power grid or superconducting cable faults in series to form a superconducting cable and power grid fault simulation model that can simulate faults at different positions of the superconducting cable.

[0065] The present application provides a modeling method for superconducting cables for electromagnetic transient simulation. The method aims to meet the needs of power grid fault analysis or superconducting cable relay protection, and the problems of traditional superconducting cable simulation models in terms of computational efficiency, calculation accuracy of key electrical quantities, and continuous switching of multiple operating states. According to the requirements of power grid fault analysis, the superconducting cable circuit simulation model is simplified and integrated into the electromagnetic transient simulation model to meet the requirements of power grid fault simulation analysis.

[0066] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0067] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0068] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0069] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalents that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A superconducting cable modeling method for electromagnetic transient simulation, characterized in that: include: A multi-state circuit simulation model of a superconducting cable is established, in which controllable switch devices are introduced into the copper skeleton branch and the support layer branch of each superconducting layer to control the opening and closing of the branch; when any superconducting layer enters the quench state, the copper skeleton and the support layer branch are connected to simulate the quench transient process; when no superconducting layer is in the quench state, the copper skeleton and all the support layer branches are disconnected to simulate the superconducting state. The multi-state circuit simulation model of a superconducting cable is shown in formula (1). in, It is a matrix composed of the self-inductance and mutual inductance of the superconducting cable copper skeleton, each support layer, each superconducting layer and each shield, which is determined by the copper skeleton size, superconducting wire and shielding layer size, and winding angle factors; [R]=diag[R 11 ,R 12 ,R 13 ,R 22 ,R 23 ...R i2 ,R i3 ,...R n2 ,R n3 ] is a diagonal matrix, whose elements are the resistances of each branch in the model; 11 , R i2 is the resistance of the copper skeleton and the supporting layer; R i3 is the resistance of the superconducting layer or the shielding layer, and its value is 0 when the superconducting cable is in steady-state operation; according to the influence of the power grid fault on the electrical quantity of the superconducting cable, by simplifying the superconducting cable multi-state circuit simulation model, a simplified simulation model of the power grid or superconducting cable fault is established, including: Establish a simplified simulation model of power grid or superconducting cable fault that does not include copper skeleton branches and supporting layer branches, controllable diode branches and diode control logic, and superconducting layer resistance; Connecting simplified simulation models of multiple power grid or superconducting cable faults in series to form superconducting cable and power grid fault simulation models simulating faults at different positions of superconducting cables; A superconducting cable model for electromagnetic transient simulation is constructed by using electromagnetic transient simulation software and a simplified simulation model of the power grid or superconducting cable fault.

2. The method according to claim 1, characterized in that The superconducting cable multi-state circuit simulation model, wherein the superconducting cable multi-state includes: The normal operating superconducting state, superconducting transient quenching state and superconducting complete quenching state of superconducting cables in power grid operation.

3. The method according to claim 1, characterized in that: The superconducting cable multi-state circuit simulation model is used to simulate the quenching process of the superconducting cable from the superconducting normal operating state to the superconducting complete quenching state.

4. The method according to claim 1, characterized in that: The impact of the power grid failure on the electrical quantities of the superconducting cable includes: The impact of faults in the power grid on the electrical quantities of the superconducting cables; and The impact of faults at different locations in the superconducting cable on various electrical quantities at different locations in the power grid.

5. The method according to claim 1, characterized in that The method of using electromagnetic transient simulation software and the simplified simulation model of the power grid or superconducting cable fault to build a superconducting cable model for electromagnetic transient simulation includes: A superconducting cable model for electromagnetic transient simulation is built using the multi-winding coil mutual inductance module in MATLAB\SIMULINK electromagnetic transient simulation software and other power grid component libraries.

6. The method according to claim 1 or 5, characterized in that: The superconducting cable model for electromagnetic transient simulation is used to simulate faults at different locations and of various fault types.

7. A superconducting cable modeling device for electromagnetic transient simulation, characterized in that: include: The superconducting cable multi-state circuit simulation model establishment unit is used to establish a superconducting cable multi-state circuit simulation model, wherein controllable switch devices are introduced into the copper skeleton branch and the support layer branch of each superconducting layer to control the opening and closing of the branch; when any superconducting layer enters the quench state, the copper skeleton and the support layer branch are connected to simulate the quench transient process; when no superconducting layer is in the quench state, the copper skeleton and all the support layer branches are disconnected to simulate the superconducting state. The superconducting cable multi-state circuit simulation model is shown in formula (1). in, It is a matrix composed of the self-inductance and mutual inductance of the superconducting cable copper skeleton, each support layer, each superconducting layer and each shield, which is determined by the copper skeleton size, superconducting wire and shielding layer size, and winding angle factors; [R]=diag[R 11 ,R 12 ,R 13 ,R 22 ,R 23 ...R i2 ,R i3 ,...R n2 ,R n3 ] is a diagonal matrix, whose elements are the resistances of each branch in the model; 11 , R i2 is the resistance of the copper skeleton and the supporting layer; R i3 is the resistance of the superconducting layer or shielding layer. When the superconducting cable is in steady state operation, its value is 0; A simplified simulation model establishment unit for a power grid or superconducting cable fault is used to establish a simplified simulation model for a power grid or superconducting cable fault by simplifying the superconducting cable multi-state circuit simulation model according to the influence of the power grid fault on the electrical quantity of the superconducting cable, including: Establish a simplified simulation model of power grid or superconducting cable fault that does not include copper skeleton branches and supporting layer branches, controllable diode branches and diode control logic, and superconducting layer resistance; A superconducting cable and power grid fault simulation model establishment subunit is used to connect multiple simplified simulation models of power grid or superconducting cable faults in series to form a superconducting cable and power grid fault simulation model that simulates faults at different positions of the superconducting cable; The superconducting cable model building unit for electromagnetic transient simulation is used to build a superconducting cable model for electromagnetic transient simulation by using electromagnetic transient simulation software and a simplified simulation model of the power grid or superconducting cable fault.

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