Superconducting tape overcurrent impulse resistance determination system and method

Abstract

The application provides a superconducting tape overcurrent impact resistance determination system and method, which comprises the following steps: detecting the voltage and current of the superconducting tape in real time, calculating the resistance of the superconducting tape, and determining structural damage when the resistance is greater than or equal to the resistance corresponding to the solder melting point in the theoretical curve; detecting the voltage and current of the superconducting tape in real time, calculating the heating amount caused by power supply on the superconducting tape through integration of time, and deriving the heating amount caused by power supply in real time, and determining structural damage when the derivative suddenly changes; calculating the difference between the cumulative heat and the heating amount caused by power supply on the superconducting tape, and determining structural damage when the difference suddenly changes. The application can accurately determine whether the superconducting tape has structural line damage caused by overcurrent impact.

Description

[0001] This application is a divisional application of the following original application:

[0002] The original application was filed on May 7, 2022.

[0003] The original application number was 202210492907.9.

[0004] Original invention application title: System and method for judging the overcurrent impact resistance of superconducting tapes Technical Field

[0005] This invention relates to the field of superconducting tapes, and more specifically, to a system and method for determining the overcurrent impact resistance of superconducting tapes. Background Technology

[0006] In January 1986, scientists Bernoulli and Müller, working at IBM's Zurich laboratory in Switzerland, first discovered that barium lanthanum copper oxide (BLA) was a high-temperature superconductor. Within one to two years, research groups worldwide raised the critical transition temperature of superconductors to above liquid nitrogen temperatures, thus eliminating the need for expensive liquid helium cooling. Over the past decade, research on superconducting power devices, primarily superconducting, has progressed rapidly, achieving significant results in areas such as superconducting energy storage, superconducting motors, superconducting cables, superconducting current limiters, superconducting transformers, and superconducting synchronous condensers.

[0007] Most superconducting power equipment utilizes superconducting materials to replace traditional copper or aluminum wires, achieving greater power, lower losses, and smaller weight and size. The large-scale application of these superconducting power devices will face cost comparisons and calculations. Superconducting current limiters are an irreplaceable product in superconducting applications. They utilize the transition of a superconducting conductor from its superconducting state to its normal state, acting like a nonlinear resistor. As an effective short-circuit current limiting device, it can quickly limit the short-circuit current to an acceptable level during a short-circuit fault, thus preventing large short-circuit currents in the power grid from posing a significant threat to the safe and stable operation of the power grid and electrical equipment. This greatly improves grid stability and enhances the reliability and security of power supply.

[0008] With the development of society and the economy, the demand for electricity is constantly increasing; at the same time, the capacity of the power grid is continuously expanding. The increase in power system capacity and grid-connected transmission leads to a corresponding increase in the potential short-circuit power and short-circuit current in the power grid. This necessitates a corresponding increase in the breaking capacity of high-voltage circuit breakers, which brings a series of problems to the construction and operation of the power system. In particular, the current maximum breaking capacity of circuit breakers is 63kA in China and 100kA abroad. If the short-circuit current exceeds the breaking limit, other shunt systems must be utilized. Therefore, limiting the short-circuit current is of paramount importance.

[0009] Currently, commercially available high-temperature superconducting tapes are divided into bismuth-based and yttrium-based materials. Bismuth-based superconductors are the first generation of superconducting materials, also known as BSCCO superconductors; yttrium-based superconductors are the second generation of superconducting materials, also known as YBCO or ReBCO superconductors.

[0010] High-temperature superconducting current limiters are currently divided into two types: inductive and resistive. Resistive current limiters are simple in principle and structure, and have a large current-limiting capacity. Inductive current limiters, especially saturated core current limiters, while having many advantages, such as the superconducting coil not losing quench and avoiding complex quenching and recovery issues, also have several problems: standard sizes must be designed for twice the fault power; only one core functions during current limiting (the other core remains saturated), which weakens the current-limiting effect and results in large core and AC winding volumes, weight, and high manufacturing costs; during normal operation, the core is saturated, resulting in significant magnetic leakage; during short circuits, the strong short-circuit current causes the core to exit bias saturation, leading to magnetic field alternation, inevitably inducing high voltage on the DC side, requiring the DC circuit to withstand high-voltage impacts; the DC power supply must be a constant current source, and if the excitation circuit has a large AC induced current, the current-limiting effect will be greatly weakened. Furthermore, the repeated saturation and desaturation of the core generates significant voltage harmonics.

[0011] First-generation high-temperature superconducting tapes are 70% silver. Silver has very low electrical resistance, making it unsuitable for immediately exhibiting high impedance after a short circuit to limit the short-circuit current. Furthermore, since my country's power transmission lines operate at 50Hz, a resistive response is required within 5ms before the first peak, a response that first-generation tapes cannot achieve. Therefore, first-generation high-temperature superconducting tapes are typically used to fabricate inductive superconducting current limiters. Resistive current limiters can only use second-generation high-temperature superconducting tapes.

[0012] Second-generation superconducting tapes, due to the hardness and brittleness of ReBCO, the superconducting current-carrying core, are generally produced using a multilayer coating process on a nickel-based alloy substrate, hence the name "coated conductors." Second-generation superconducting tapes typically consist of a base tape, a buffer layer (transition layer), a superconducting layer, and a protective layer. The metal substrate provides excellent mechanical properties for the tape. The transition layer serves two purposes: firstly, it prevents inter-element diffusion between the superconducting layer and the metal substrate; secondly, the topmost transition layer provides a good template for the epitaxial growth of the superconducting layer, improving the YBCO grain alignment quality. To prepare coated conductors with excellent superconducting properties, the superconducting layer needs a consistent biaxial texture. Biaxial texture refers to a nearly uniform grain alignment in both the a / b axis and the c axis (the c axis is perpendicular to the a / b plane). Since achieving a high degree of alignment in the a / b axis direction (in-plane texture) of YBCO thin films is relatively difficult, and poor in-plane texture significantly reduces superconducting performance. Therefore, YBCO superconducting thin films need to be epitaxially grown on a transition layer that already possesses biaxial texture and a matched lattice. There are two main technical routes for fabricating biaxial texture: one is roll-assisted biaxial texture substrate technology, and the other is ion beam-assisted deposition technology. Common techniques for fabricating ReBCO superconducting layers include pulsed laser deposition, metal-organic chemical vapor deposition, and reactive co-evaporation. The protective layer is mainly used to protect the superconducting film, and is generally a 1-5 μm silver layer deposited on the surface of the superconducting tape.

[0013] However, these superconducting tapes still have many weaknesses due to limitations in their materials or manufacturing processes, especially when applied to specific superconducting devices. During processing, these materials require joint fabrication, coil winding, epoxy impregnation, and vacuum casting. During application, they are subjected to rapid heating and cooling, numerous thermal cycles, stress from strong magnetic fields, and high-current impacts, among other complex operating conditions. It can be said that superconducting tapes with only preliminary silver protection cannot meet the performance requirements of actual superconducting applications, especially in terms of electrical and mechanical properties. Therefore, a common practice is to perform surface copper plating, specifically electroplating a 1-80µm copper layer onto the silver-plated superconducting tape surface.

[0014] Electroplated superconducting tapes can adapt to some application environments, but they still cannot meet the requirements for many superconducting applications, especially for superconducting resistive current limiters. The main consideration is the high resistance after quenching, requiring the tape to withstand certain mechanical impacts. In this case, a protective layer made of a material with high thermal conductivity, high strength, and high resistance, such as stainless steel, is preferable. Therefore, it is necessary to encapsulate and reinforce the superconducting tape with stainless steel, i.e., to achieve a complete encapsulation treatment of the superconducting tape using a stainless steel coating process through hot-dip galvanizing. According to patent document CN201710416026.8, encapsulated and reinforced superconducting tapes have several advantages, such as significantly enhanced surface oxidation resistance, machinability, fatigue resistance, delamination stress resistance, tensile stress resistance, steady-state overcurrent resistance, and transient overcurrent resistance.

[0015] Therefore, the protective post-treatment of superconducting tapes used in superconducting resistive current limiters is silver plating, copper plating, or stainless steel encapsulation.

[0016] The key performance indicators (KPIs) for superconducting tapes include critical current, room-temperature resistance, unit weight, and ability to withstand surge current. The critical current is the point at which the tape transitions from a superconducting state to a normal state. Inconsistent critical currents in the current limiter will result in inconsistent resistance. After the superconducting tape transitions to a normal state, the resistance primarily depends on the tape's unit weight and room-temperature resistance. The ability to withstand surge current is an experimental value, while the critical current, room-temperature resistance, and unit weight are controlled values ​​during the fabrication process. After depositing a silver protective layer over the superconducting layer, the critical current can be tested using the transmission method or electromagnetic induction method. Through selection, the critical current of the superconducting tape can be kept consistent. Since the same current limiter typically uses the same specification of superconducting tape, the unit weight of the superconducting tape can also be relatively easily kept consistent. The room-temperature resistance of the superconducting tape can also be kept consistent using the method in CN201711280066.0.

[0017] Traditional testing methods involve using a large power supply, setting parameters to subject the superconducting tape to a current surge, and then testing whether the critical current of the superconducting tape degrades. Extensive testing revealed that Hastelloy-based superconducting tapes, exemplified by those using stainless steel packaging from Shanghai Superconducting Technologies, exhibit lateral tape delamination during testing, but the critical current does not decay at this stage.

[0018] Therefore, the delamination of superconducting tapes can be used as a supplementary criterion to indicate structural damage. However, structural damage is difficult to observe, and delamination on the sides is often not obvious. Sometimes, the solder on local surfaces may melt again, which should also be identified as structural damage to the superconducting tape, but these phenomena are even more difficult to detect.

[0019] In some tests, temperature sensors are installed on the surface of the tape. However, temperature transmission in liquid nitrogen can be inaccurate. Furthermore, anything installed on the tape surface will impact the tape during the impact, causing localized compressive stress on the superconducting tape. This hinders the release of large stress generated by the large current flowing through the tape during the impact, significantly reducing the superconducting tape's resistance to overcurrent impact. Summary of the Invention

[0020] To address the shortcomings of existing technologies, the purpose of this invention is to provide a system and method for determining the overcurrent impact resistance of superconducting tapes.

[0021] A method for determining the overcurrent impact resistance of superconducting tapes according to the present invention includes:

[0022] Mass calculation steps: Calculate the mass of each metal layer based on the cross-sectional area, corresponding length, and density of each metal layer in the superconducting tape;

[0023] Resistance calculation steps: Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, calculate the resistance of each metal layer of the superconducting tape at each temperature. Then, process the resistance of each metal layer at each temperature according to the parallel conductor formula to obtain the total resistance of the superconducting tape.

[0024] Temperature-resistance fitting correlation steps: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated.

[0025] The current surge resistance test procedure includes any one or more of the following test methods:

[0026] The voltage and current of the superconducting tape are detected in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage is determined.

[0027] The voltage and current of the superconducting tape are monitored in real time. The heating amount caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the heating amount caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage is determined.

[0028] The system monitors the voltage and current of the superconducting tape in real time, calculates its resistance, and estimates its temperature based on the calculated resistance. It then calculates the accumulated heat on the superconducting tape by integrating the specific heat, mass, and temperature changes of each metal layer over time. Alternatively, it monitors the voltage and current of the superconducting tape in real time, calculates the heating caused by energizing the tape over time, and then calculates the difference between the accumulated heat and the heating caused by energizing. A sudden change in this difference indicates structural damage.

[0029] Preferably, the superconducting tape includes superconducting tapes used in each packaging process stage.

[0030] Preferably, the method further includes a surface inspection step: when a local melting point is detected on the surface of the superconducting tape, it is determined that the superconducting tape is structurally damaged.

[0031] Preferably, the method for calculating the mass of the superconducting tape includes:

[0032] m sc =(ρ Has S Has +ρ Ag S Ag +ρ Cu S Cu +ρ Sus S Sus +ρ Sn S Sn )L; or,

[0033] m ScAg =(ρ Has S Has +ρ Ag S Ag )L;

[0034] Where, m Sc For the mass of the superconducting tape after stainless steel encapsulation, m ScAg For the mass of the superconducting tape after silver plating, ρ Has S is the baseband layer density. Has ρ is the cross-sectional area of ​​the baseband layer. Ag S is the density of the silver layer. Ag ρ is the cross-sectional area of ​​the silver layer. Cu S is the density of the copper layer. Cu ρ is the cross-sectional area of ​​the copper layer. Sus S represents the density of the stainless steel layer. Sus ρ is the cross-sectional area of ​​the stainless steel layer. Sn S represents the solder layer density. Sn Where L is the cross-sectional area of ​​the solder layer and L is the length of the superconducting tape.

[0035] Preferably, processing the resistance of each metal layer at each temperature according to the conductor parallel connection formula includes:

[0036] or,

[0037]

[0038] Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R Has (T) represents the relationship between the baseband resistance and temperature T, RAg (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus (T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

[0039] A superconducting tape overcurrent impact resistance determination system provided by the present invention includes:

[0040] Mass calculation module: Calculates the mass of each metal layer based on the cross-sectional area, corresponding length, and density of each metal layer in the superconducting tape;

[0041] Resistance calculation module: Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, the resistance of each metal layer of the superconducting tape at each temperature is calculated, and the resistance of each metal layer at each temperature is processed according to the conductor parallel formula to obtain the total resistance of the superconducting tape.

[0042] Temperature-resistance fitting and correlation module: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated.

[0043] The overcurrent shock resistance assessment module includes one or more of the following assessment methods:

[0044] The voltage and current of the superconducting tape are detected in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage is determined.

[0045] The voltage and current of the superconducting tape are monitored in real time. The heating amount caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the heating amount caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage is determined.

[0046] The system monitors the voltage and current of the superconducting tape in real time, calculates its resistance, and estimates its temperature based on the calculated resistance. It then calculates the accumulated heat on the superconducting tape by integrating the specific heat, mass, and temperature changes of each metal layer over time. Alternatively, it monitors the voltage and current of the superconducting tape in real time, calculates the heating caused by energizing the tape over time, and then calculates the difference between the accumulated heat and the heating caused by energizing. A sudden change in this difference indicates structural damage.

[0047] Preferably, the superconducting tape includes superconducting tapes used in each packaging process stage.

[0048] Preferably, it also includes a surface detection module: when a local melting point is detected on the surface of the superconducting tape, it is determined that the superconducting tape is structurally damaged.

[0049] Preferably, the method for calculating the mass of the superconducting tape includes:

[0050] m Sc =(ρ Has S Has +ρ Ag S Ag +ρ Cu S Cu +ρ Sus S Sus +ρ Sn S Sn )L; or,

[0051] m ScAg =(ρ Has S Has +ρ Ag S Ag )L;

[0052] Where, m Sc For the mass of the superconducting tape after stainless steel encapsulation, m ScAg For the mass of the superconducting tape after silver plating, ρ Has S is the baseband layer density. Has ρ is the cross-sectional area of ​​the baseband layer. Ag S is the density of the silver layer. Ag ρ is the cross-sectional area of ​​the silver layer. Cu S is the density of the copper layer. Cu ρ is the cross-sectional area of ​​the copper layer. Sus S represents the density of the stainless steel layer. Sus ρ is the cross-sectional area of ​​the stainless steel layer. Sn S represents the solder layer density. Sn Where L is the cross-sectional area of ​​the solder layer and L is the length of the superconducting tape.

[0053] Preferably, processing the resistance of each metal layer at each temperature according to the conductor parallel connection formula includes:

[0054] or,

[0055]

[0056] Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R. Has (T) represents the relationship between the baseband resistance and temperature T, R Ag (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus(T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] This invention can accurately determine whether there is structural line damage caused by overcurrent impact in superconducting tapes, and is especially suitable for determining overcurrent impact on superconducting tapes whose surface is not visible after surface insulation wrapping. Attached Figure Description

[0059] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0060] Figure 1 This is a flowchart of the process of the present invention;

[0061] Figure 2 The waveforms of the inrush current and inrush voltage are shown.

[0062] Figure 3 The graph shows the resistance and temperature of the superconducting tape under transient impact.

[0063] Figure 4 These are measured curves showing the changes in resistivity and specific heat of superconducting tapes with temperature. Detailed Implementation

[0064] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0065] like Figure 1 As shown, this invention provides a method for determining the overcurrent impact resistance of superconducting tapes, comprising:

[0066] Mass calculation steps: Based on the cross-sectional area, corresponding length, and density of each metal layer of the superconducting tape, calculate the mass of each metal layer, and sum the masses of each metal layer to obtain the mass of the superconducting tape. The superconducting tape in this application includes superconducting tapes at each packaging process stage; that is, the present invention applies to superconducting tapes at each packaging process stage. The method for calculating the mass of the superconducting tape includes: the mass m of the superconducting tape after the stainless steel packaging process. Sc =(ρ Has S Has +ρ Ag S Ag +ρ Cu SCu +ρ Sus S Sus +ρ Sn S Sn L; or, the mass m of the superconducting tape after the silver plating process. ScAg =(ρ Has S Has +ρ Ag S Ag L. Where, m Sc For the mass of the superconducting tape after stainless steel encapsulation, m ScAg For the mass of the superconducting tape after silver plating, ρ Has S is the baseband layer density. Has ρ is the cross-sectional area of ​​the baseband layer. Ag S is the density of the silver layer. Ag ρ is the cross-sectional area of ​​the silver layer. Cu S is the density of the copper layer. Cu ρ is the cross-sectional area of ​​the copper layer. Sus S represents the density of the stainless steel layer. Sus ρ is the cross-sectional area of ​​the stainless steel layer. Sn S represents the solder layer density. Sn Where L is the cross-sectional area of ​​the solder layer and L is the length of the superconducting tape.

[0067] Resistance calculation steps: Superconducting tapes consist of a multi-layered structure. The metal layers of superconducting tapes used in superconducting resistive current limiters mainly include: a silver stabilizing layer, a copper stabilizing layer, a stainless steel reinforcing layer, and a solder layer. In the non-superconducting state, the superconducting layer and buffer layer in the superconducting tape are oxides, and their resistivity is much greater than that of the metal layers; therefore, they are not considered in the resistance calculation. Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, the resistance of each metal layer at each temperature is calculated. The total resistance of the superconducting tape is obtained by processing the resistance of each metal layer at each temperature using the parallel conductor formula. or, Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R. Has (T) represents the relationship between the baseband resistance and temperature T, R Ag (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus (T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

[0068] Temperature-resistivity fitting correlation steps: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated. Ignoring the influence of the buffer layer and superconducting oxide layer on the resistance and specific heat of the superconducting tape, within the temperature range of 77K-400K, the resistivity and specific heat parameters of the aforementioned metallic materials are approximately considered to exhibit a linear change with temperature. The theoretical curve of the resistance of a specific superconducting tape as a function of temperature can then be obtained through calculation.

[0069] Steps for determining resistance to overcurrent shock:

[0070] The voltage and current of the superconducting tape are monitored in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage can be determined.

[0071] The voltage and current of the superconducting tape are monitored in real time. The amount of heat caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the amount of heat caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage can be determined.

[0072] The voltage and current of the superconducting tape are monitored in real time, and the resistance of the superconducting tape is calculated. The temperature of the superconducting tape is estimated based on the calculated resistance. The heat accumulated on the superconducting tape is calculated by integrating the specific heat, mass, and temperature change values ​​of each metal layer over time. Alternatively, the voltage and current of the superconducting tape are monitored in real time, and the heating caused by energizing the superconducting tape is calculated by integrating over time. Then, the difference between the accumulated heat on the superconducting tape and the heating caused by energizing is calculated. When the difference changes abruptly, structural damage can be determined.

[0073] At the same time, surface inspection can also be used to assist in the judgment. When local melting points are detected on the surface of the superconducting tape, it is determined that the superconducting tape is structurally damaged.

[0074] The transient impact waveforms of the superconducting tape are shown below. Figure 2 As shown. Figure 3 The resistance and temperature are based on Figure 2 Calculations showed that the resistance increased rapidly with the impact of a large current. Since the resistance of the metal layer changes almost linearly with temperature between 77K and 600K, the corresponding relationship for this superconducting tape was found, and the temperature corresponding to the resistance was plotted as a coordinate axis on a graph. Figure 3 The right side. The horizontal dashed line in the figure represents the temperature of the superconducting tape at 456K, which is the melting point of the solder.

[0075] The superconducting tape was observed after each transient impact. After a normal impact, the surface of the superconducting tape remained the same as before the impact. However, when the superconducting tape was subjected to a transient impact of 1.8 kV, with a peak impact current of 3925.9 A, localized melting occurred on the surface of the superconducting tape. Figure 3 As observed, the temperature at 1.8kV is close to the melting point of solder. During a transient impact at 1.9kV, with a peak impact current of 4144.0A, the immense impact force bent the superconducting tape, and small cracks appeared at its edges. When impacted by a 2.0kV charged capacitor, with a peak impact current of 4361.1A, the cracks at the tape's edges were further amplified, and scorch marks appeared on the surface of the superconducting tape.

[0076] The main factor affecting the temperature of the superconducting band is the Joule heat generated during the quenching process, which is the result of a combination of factors such as quenching resistance, current, and quenching time. The change of the Joule heat Q generated in the superconducting band over time is calculated as follows:

[0077]

[0078] Where t is the quench time and R(t) is the time corresponding to the quench resistor.

[0079] Figure 4 The graph illustrates the change in resistance per unit length of superconducting tape as a function of impact heat after each impact. The temperature corresponding to the resistance is plotted on the right side as a coordinate axis. The horizontal dashed line represents the temperature of the superconducting tape at 456K, which is the melting point of solder, while the diagonal dashed line represents the original trend line (the theoretical curve). The graph shows that with each increase in impact energy, the resistance increases more rapidly than the previous one. The superconducting resistance response reflects the process of heat accumulation and increase on the tape. The heat from the impact causes an increase in the resistance of the superconducting tape, which in turn leads to a further increase in heat generation. The accumulated heat of the superconducting tape itself can be expressed by the following formula:

[0080]

[0081] from Figure 4 As can be seen, when subjected to a transient impact of 1.9kV, the measured RQ curve deviated from the original trend line, indicating that structural damage occurred in the strip during the impact process. The point where this damage occurred happened precisely when the strip temperature reached the solder melting point.

[0082] This invention also provides a system for determining the overcurrent impact resistance of superconducting tapes, comprising:

[0083] Mass Calculation Module: Based on the cross-sectional area, corresponding length, and density of each metal layer of the superconducting tape, the mass of each metal layer is calculated, and the total mass of the superconducting tape is obtained. The superconducting tape in this application includes superconducting tapes at each packaging process stage; that is, the present invention applies to superconducting tapes at each packaging process stage. The method for calculating the mass of the superconducting tape includes: the mass m of the superconducting tape after the stainless steel packaging process.Sx =(ρ Has S Has +ρ Ag S Ag +ρ Cu S Cu +ρ Sus S Sus +ρ Sn S Sn L; or, the mass m of the superconducting tape after the silver plating process. ScAg =(ρ Has S Has +ρ Ag S Ag L. Where, m Sc For the mass of the superconducting tape after stainless steel encapsulation, m ScAg For the mass of the superconducting tape after silver plating, ρ Has S is the baseband layer density. Has ρ is the cross-sectional area of ​​the baseband layer. Ag S is the density of the silver layer. Ag ρ is the cross-sectional area of ​​the silver layer. Cu S is the density of the copper layer. Cu ρ is the cross-sectional area of ​​the copper layer. Sus S represents the density of the stainless steel layer. Sus ρ is the cross-sectional area of ​​the stainless steel layer. Sn S represents the solder layer density. Sn Where L is the cross-sectional area of ​​the solder layer and L is the length of the superconducting tape.

[0084] Resistance Calculation Module: Superconducting tapes consist of a multi-layered structure. The metal layers of the superconducting tape used in superconducting resistive current limiters mainly include: a silver stabilizing layer, a copper stabilizing layer, a stainless steel reinforcing layer, and a solder layer. In the non-superconducting state, the superconducting layer and buffer layer in the superconducting tape are oxides, and their resistivity is much greater than that of the metal layers; therefore, they are not considered in the resistance calculation. Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, the resistance of each metal layer at each temperature is calculated. The total resistance of the superconducting tape is then obtained by processing the resistance of each metal layer at each temperature using the parallel conductor formula. or, Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R. Has (T) represents the relationship between the baseband resistance and temperature T, R Ag (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus(T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

[0085] Temperature-resistance fitting and correlation module: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated. Ignoring the influence of the buffer layer and superconducting oxide layer on the resistance and specific heat of the superconducting tape, within the temperature range of 77K-400K, the resistivity and specific heat parameters of the aforementioned metallic materials are approximately considered to exhibit a linear change with temperature. Theoretical curves of the resistance as a function of temperature for specific superconducting tapes can be obtained through calculation.

[0086] Overcurrent impact resistance determination module:

[0087] The voltage and current of the superconducting tape are monitored in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage can be determined.

[0088] The voltage and current of the superconducting tape are monitored in real time. The amount of heat caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the amount of heat caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage can be determined.

[0089] The voltage and current of the superconducting tape are monitored in real time, and the resistance of the superconducting tape is calculated. The temperature of the superconducting tape is estimated based on the calculated resistance. The heat accumulated on the superconducting tape is calculated by integrating the specific heat, mass, and temperature change values ​​of each metal layer over time. Alternatively, the voltage and current of the superconducting tape are monitored in real time, and the heating caused by energizing the superconducting tape is calculated by integrating over time. Then, the difference between the accumulated heat on the superconducting tape and the heating caused by energizing is calculated. When the difference changes abruptly, structural damage can be determined.

[0090] At the same time, surface inspection can also be used to assist in the judgment. When local melting points are detected on the surface of the superconducting tape, it is determined that the superconducting tape is structurally damaged.

[0091] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0092] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for determining the overcurrent impact resistance of superconducting tapes, characterized in that, include: Mass calculation steps: Calculate the mass of each metal layer based on the cross-sectional area, corresponding length, and density of each metal layer in the superconducting tape; Resistance calculation steps: Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, calculate the resistance of each metal layer of the superconducting tape at each temperature. Then, process the resistance of each metal layer at each temperature according to the parallel conductor formula to obtain the total resistance of the superconducting tape. Temperature-resistance fitting correlation steps: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated. The procedure for determining resistance to overcurrent shock includes the determination method: The voltage and current of the superconducting tape are detected in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage is determined. The voltage and current of the superconducting tape are monitored in real time. The heating amount caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the heating amount caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage is determined. The voltage and current of the superconducting tape are monitored in real time, the resistance of the superconducting tape is calculated, the temperature of the superconducting tape is estimated based on the calculated resistance, and the heat accumulated on the superconducting tape is calculated by integrating the specific heat, mass and temperature change values ​​of each metal layer over time; the voltage and current of the superconducting tape are monitored in real time, and the heating amount caused by energizing the superconducting tape is calculated by integrating over time. Then, the difference between the accumulated heat on the superconducting tape and the heating caused by the current is calculated. When the difference changes abruptly, structural damage is determined. When local melting points are detected on the surface of the superconducting tape, structural damage to the superconducting tape is determined.

2. The method for determining the overcurrent impact resistance of superconducting tapes according to claim 1, characterized in that, The superconducting tape includes superconducting tapes used in each packaging process stage.

3. The method for determining the overcurrent impact resistance of superconducting tapes according to claim 1, characterized in that, The methods for calculating the mass of superconducting tapes include: ;or, ； Where, m Sc To ensure the quality of the superconducting tape after stainless steel encapsulation. For the mass of the superconducting tape after silver plating, ρ Has Baseband layer density, ρ is the cross-sectional area of ​​the baseband layer. Ag The density of the silver layer, ρ is the cross-sectional area of ​​the silver layer. Cu Copper layer density, ρ is the cross-sectional area of ​​the copper layer. Sus Density of stainless steel layer ρ is the cross-sectional area of ​​the stainless steel layer. Sn The density of the solder layer. This is the cross-sectional area of ​​the solder layer. denoted as the length of the superconducting tape.

4. The method for determining the overcurrent impact resistance of superconducting tapes according to claim 1, characterized in that, The resistance of each metal layer at each temperature is treated according to the parallel conductor formula, including: ;or, ； Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R. Has (T) represents the relationship between the baseband resistance and temperature T, R Ag (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus (T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

5. A system for determining the overcurrent impact resistance of superconducting tapes, characterized in that, include: Mass calculation module: Calculates the mass of each metal layer based on the cross-sectional area, corresponding length, and density of each metal layer in the superconducting tape; Resistance calculation module: Based on the mass of each metal layer of the superconducting tape and the resistivity of each metal layer at each temperature, the resistance of each metal layer of the superconducting tape at each temperature is calculated, and the resistance of each metal layer at each temperature is processed according to the conductor parallel formula to obtain the total resistance of the superconducting tape. Temperature-resistance fitting and correlation module: By fitting the total resistance of the superconducting tape to temperature at multiple points, the theoretical curve of the total resistance of the superconducting tape as a function of temperature is calculated. The overcurrent shock resistance assessment module includes the assessment method: The voltage and current of the superconducting tape are detected in real time, and the resistance of the superconducting tape is calculated. When the resistance value is greater than or equal to the resistance value corresponding to the solder melting point in the theoretical curve, structural damage is determined. The voltage and current of the superconducting tape are monitored in real time. The heating amount caused by energizing the superconducting tape is calculated by integrating over time. The derivative of the heating amount caused by energizing is calculated in real time. When the derivative changes abruptly, structural damage is determined. The voltage and current of the superconducting tape are monitored in real time, the resistance of the superconducting tape is calculated, the temperature of the superconducting tape is estimated based on the calculated resistance, and the heat accumulated on the superconducting tape is calculated by integrating the specific heat, mass and temperature change values ​​of each metal layer over time; the voltage and current of the superconducting tape are monitored in real time, and the heating amount caused by energizing the superconducting tape is calculated by integrating over time. Then, the difference between the accumulated heat on the superconducting tape and the heating caused by the current is calculated. When the difference changes abruptly, structural damage is determined. When local melting points are detected on the surface of the superconducting tape, structural damage to the superconducting tape is determined.

6. The superconducting tape overcurrent impact resistance determination system according to claim 5, characterized in that, The superconducting tape includes superconducting tapes used in each packaging process stage.

7. The superconducting tape overcurrent impact resistance determination system according to claim 5, characterized in that, The methods for calculating the mass of superconducting tapes include: ;or, ； Where, m Sc To ensure the quality of the superconducting tape after stainless steel encapsulation. For the mass of the superconducting tape after silver plating, ρ Has Baseband layer density, ρ is the cross-sectional area of ​​the baseband layer. Ag The density of the silver layer, ρ is the cross-sectional area of ​​the silver layer. Cu Copper layer density, ρ is the cross-sectional area of ​​the copper layer. Sus Density of stainless steel layer ρ is the cross-sectional area of ​​the stainless steel layer. Sn The density of the solder layer. This is the cross-sectional area of ​​the solder layer. denoted as the length of the superconducting tape.

8. The superconducting tape overcurrent impact resistance determination system according to claim 5, characterized in that, The resistance of each metal layer at each temperature is treated according to the parallel conductor formula, including: ;or, ； Among them, R Sc (T) represents the relationship between the resistance of the superconducting strip after stainless steel encapsulation and temperature T, R ScAg (T) represents the relationship between the resistance of the silver-plated superconducting tape and temperature T, R. Has (T) represents the relationship between the baseband resistance and temperature T, R Ag (T) represents the relationship between the resistivity of the silver layer and temperature T, R Cu (T) represents the relationship between the resistance of the copper layer and temperature T, R Sus (T) represents the relationship between the resistance of the stainless steel layer and temperature T, R Sn (T) is the formula for the change of solder layer resistance with temperature T.

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