Method, device and system for testing performance of grounding material

Abstract

The invention provides a method, device and system for testing the performance of a grounding material, and belongs to the field of electric power safety. The method comprises the following steps: acquiring first temperature change record data of a to-be-tested grounding material in a through-flow heating test process and a natural cooling test process under a target current value condition; determining the specific heat capacity and emissivity of the grounding material to be measured according to the first temperature change record data; respectively acquiring second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be measured under the condition of two or more different set current values; and according to the second temperature change record data corresponding to each current value, respectively calculating stage heat conductivity coefficients corresponding to the temperature rise process and the cooling process, and determining the material heat conductivity coefficient according to each stage heat conductivity coefficient. According to the invention, the comprehensiveness and accuracy of grounding material performance test results can be improved.

Description

Technical Field

[0001] The present invention relates to the field of electric power safety technology, and in particular to a method, device and system for testing the performance of grounding materials. Background Art

[0002] Grounding and anti-corrosion materials play a vital role in the power system. They not only ensure the stable operation of power facilities, but also extend the service life of equipment. With the advancement of technology, the performance of grounding and anti-corrosion materials is also constantly improving to meet the increasingly complex and harsh power environment requirements. In the existing technology, there are many types of grounding and anti-corrosion materials, which resist corrosion through different mechanisms, such as chemical stability, electrochemical protection, and physical barriers.

[0003] In terms of performance testing of grounding anti-corrosion materials, relevant technologies provide testing standards and methods. Conductivity testing is the key to evaluating the conductivity of materials, and is usually carried out using methods such as the four-probe method or the DC resistance method. Corrosion resistance testing simulates various corrosion environments, such as salt spray tests, acid-base corrosion tests, etc., to verify the corrosion resistance of materials under different conditions. The purpose of grounding anti-corrosion materials is to improve the corrosion resistance of the grounding system while retaining good electrical properties. At present, there is a lack of a solution that takes into account both electrical performance and corrosion resistance testing to assist in the selection of grounding materials. Summary of the invention

[0004] The embodiments of the present invention provide a method, a device and a system for testing the performance of a grounding material, so as to solve the problem of how to balance the testing of electrical performance and anti-corrosion performance.

[0005] In a first aspect, an embodiment of the present invention provides a method for testing the performance of a grounding material, comprising:

[0006] Obtaining first temperature change record data of the grounding material to be tested during the through-current heating test process and the natural cooling test process under the condition of the target current value;

[0007] Determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data;

[0008] Respectively obtain the second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions;

[0009] According to the second temperature change record data corresponding to each current value, the stage thermal conductivity corresponding to the temperature rise process and the cooling process is calculated respectively, and the material thermal conductivity is determined according to the thermal conductivity of each stage.

[0010] In a second aspect, an embodiment of the present invention provides a device for testing the performance of a grounding material, comprising:

[0011] An acquisition module is used to acquire first temperature change record data of the grounding material to be tested during a current heating test process and a natural cooling test process under a target current value condition;

[0012] A determination module, used to determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data;

[0013] The acquisition module is also used to respectively acquire second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions;

[0014] The determination module is also used to calculate the stage thermal conductivity corresponding to the temperature rise process and the cooling process respectively according to the second temperature change record data corresponding to each current value, and determine the thermal conductivity of the material according to the thermal conductivity of each stage.

[0015] In a third aspect, an embodiment of the present invention provides a system for testing the performance of grounding materials, characterized in that it comprises: the device for testing the performance of grounding materials described in the second aspect, a power frequency constant current power supply, a square convection shielding box, a current detection unit, a voltage detection unit, a thermocouple measurement array and a corresponding multi-channel temperature recorder; the power frequency constant current power supply is an adjustable power frequency constant current process-controlled current source;

[0016] Wherein, each thermocouple in the thermocouple measurement array is arranged on the surface of the test conductor inside the square convection shielding box;

[0017] The thermocouples are arranged according to set intervals;

[0018] The industrial frequency constant current power supply, the current detection unit and the voltage detection unit are connected to the grounding material to be tested and the device for testing the performance of the grounding material through current wire clamps.

[0019] The embodiments of the present invention provide a method, device and system for testing the performance of grounding materials, by setting a target current value condition and two or more different set current value conditions, and measuring the specific heat capacity, emissivity and thermal conductivity of the grounding material to be tested respectively. The specific heat capacity reflects the ability of the material to absorb or release heat, while the emissivity describes the efficiency of the material to emit energy in the form of radiation. Therefore, setting the target current value condition in a targeted manner can improve the accuracy of the calculation of the specific heat capacity and emissivity. The thermal conductivity of the material is affected by many factors, including temperature, pressure and current density. Therefore, measuring and calculating the thermal conductivity of the material under two or more different set current value conditions can avoid the systematic deviation caused by a single test condition, improve the accuracy of the calculation of the thermal conductivity of the material, and make the thermal conductivity of the material calculated in the end closer to the actual thermal conductivity value. The embodiments of the present application improve the accuracy of the test results while ensuring the comprehensiveness of the performance test of the grounding material. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a system for testing the performance of grounding materials provided by an embodiment of the present invention;

[0022] Figure 2 A schematic structural diagram of a square convection shielding box provided in an embodiment of the present invention;

[0023] Figure 3 is a flow chart of a method for testing the performance of grounding materials provided by an embodiment of the present invention;

[0024] Figure 4 is a flowchart for determining the thermal conductivity of a material provided by an embodiment of the present invention;

[0025] Figure 5a It is the temperature change curve in the process of determining the thermal conductivity of the material;

[0026] Figure 5b It is the power variation curve in the process of determining the thermal conductivity of the material;

[0027] Figure 6 is a flow chart of a method for testing the performance of grounding materials provided by another embodiment of the present invention;

[0028] Figure 7It is a schematic diagram of the structure of a device for testing the performance of grounding materials provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0030] The purpose of the new grounding anti-corrosion material is to improve the corrosion resistance of the grounding system while retaining good electrical performance. When an asymmetric short-circuit fault occurs in the power system, the grounding system will withstand a short-term short-circuit current of up to tens of kA. At present, there is a lack of test solutions for the temperature rise characteristics and current capacity characteristics of new grounding anti-corrosion materials. This solution innovatively provides a test solution that takes into account both temperature rise characteristics and current capacity characteristics.

[0031] The test system for grounding anti-corrosion materials provided in this application can monitor physical quantities such as voltage, current, and temperature rise by building a semi-adiabatic environment; the emissivity and specific heat capacity of the grounding anti-corrosion materials can be obtained through a 1s / 1000A current heating-natural cooling test; on this basis, a long-term current temperature rise-natural cooling test is carried out through three test currents of 500A, 700A, and 1kA to obtain the thermal conductivity of the grounding anti-corrosion materials; finally, the current capacity of the grounding anti-corrosion materials is calculated in combination with the short-term heating characteristics of the power system short-circuit fault. This application provides a technical reference for the application of grounding anti-corrosion materials and helps to assist in the selection of grounding anti-corrosion materials.

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0033] Figure 1 The schematic diagram of the structure of the system for testing the performance of grounding materials provided by the embodiment of the present invention is as follows. Figure 1 As shown, the system for testing the performance of grounding materials includes: a power frequency constant current power supply, a square convection shielding box, a current detection unit, a voltage detection unit, a thermocouple measurement array and a corresponding multi-channel temperature recorder. Among them, the power frequency constant current power supply is an adjustable power frequency constant current process-controlled current source, and the current on and off time is controllable. Optionally, the current output range of the power frequency constant current power supply is 1A~1k.

[0034] like Figure 1The current wire clamp is used to connect the grounded anti-corrosion material test sample with the test current wire. The test current wire is connected to the current detection unit and the voltage detection unit to collect the current and voltage flowing through the grounded anti-corrosion material test sample.

[0035] There are one current detection unit I and one voltage detection unit V, and the thermocouple measurement array is of PT100 type. Each thermocouple in the thermocouple measurement array is arranged on the surface of the test conductor inside the square convection shielding box, and the thermocouples are arranged according to the set intervals.

[0036] In a specific embodiment, a thermocouple is arranged every 5 cm, and a total of 14 thermocouples are arranged. The channel measurement sampling rate of the multi-channel temperature recorder is 50 Hz; the sampling rate of the current detection unit and the voltage detection unit is 10 kHz.

[0037] Figure 2 A schematic diagram of the structure of a square convection shielding box provided by an embodiment of the present invention is shown in FIG. Figure 2 As shown, the size of the square convection shielding box is L2*0.3m*0.3m, L2=0.75m. A 0.15mm*0.01mm opening is opened in the center of the side plate, and a 0.19mm*0.05mm mica gasket is set at the outer edge of the opening.

[0038] Optionally, the square convection shield box has semi-insulated side panels made of polyetherimide on both sides.

[0039] The method for testing the performance of grounding materials provided in the embodiment of the present application is completed on the basis of the above-mentioned system. During the specific implementation process, the current value and the current on-off of the grounding anti-corrosion material are adjusted by an industrial frequency constant current power supply.

[0040] Figure 3 The implementation flow chart of the method for testing the performance of grounding materials provided by the embodiment of the present invention is described in detail as follows:

[0041] Step 301, obtaining first temperature change record data of the grounding material to be tested during a current heating test process and a natural cooling test process under a target current value condition.

[0042] The first temperature change record data includes the initial value, change value and time point of the temperature, etc., to ensure the accuracy and completeness of the data.

[0043] Optionally, during the through-flow heating test process and the natural cooling test process, the temperature sampling values ​​are recorded using the same sampling frequency.

[0044] Step 302: determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data.

[0045] Optionally, the target current value conditions include: the current value is 1kA and the experimental time is 1s, that is, the heating current test is performed using a 1kA power frequency current for 1s.

[0046] Among them, steps 301 and 302 are intended to measure the specific heat capacity and emissivity of the grounding material to be tested. The specific heat capacity is the degree of temperature change of the material when absorbing or releasing heat, and the emissivity is the ability of the material to emit thermal radiation. Therefore, the target current value needs to be large enough to ensure that the material can achieve sufficient temperature change during the test, thereby ensuring the accuracy of the measurement results.

[0047] Generally, the thermal conductivity of a material changes as the current increases. When measuring the thermal conductivity, the current value is set to be less than or equal to the target current value.

[0048] Step 303 , respectively obtaining second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions.

[0049] Step 304, calculating the thermal conductivity of the stages corresponding to the temperature rise process and the cooling process respectively according to the second temperature change record data corresponding to each current value, and determining the thermal conductivity of the material according to the thermal conductivity of each stage.

[0050] Among them, the thermal conductivity is calculated based on two or more different set current value conditions, which facilitates a more comprehensive understanding of the thermal conductivity of the material and improves the accuracy of the calculation results of the thermal conductivity of the material.

[0051] Generally, the thermal conductivity of a material will change as the current increases. For different set current values, the duration of the temperature rise process and the cooling process are different. In the specific implementation process, the temperature rise process and the cooling process are divided according to the real-time temperature of the anti-corrosion material to be tested, so as to unify the standards and improve the accuracy of the thermal conductivity calculation results.

[0052] Optionally, the set current value is determined based on the target current value and the number of different set current value conditions to obtain richer data to ensure the representativeness of the set current value and to construct a complete temperature change model to reflect the thermal conductivity corresponding to different temperature ranges.

[0053] In this embodiment, by setting a target current value condition and two or more different set current value conditions, the specific heat capacity, emissivity and thermal conductivity of the grounding material to be tested are measured respectively. The specific heat capacity reflects the ability of the material to absorb or release heat, while the emissivity describes the efficiency of the material to emit energy in the form of radiation. Therefore, setting the target current value condition in a targeted manner can improve the accuracy of the calculation of specific heat capacity and emissivity. The thermal conductivity of the material is affected by many factors, including temperature, pressure, and current density. Therefore, measuring and calculating the thermal conductivity of the material under two or more different set current value conditions can avoid the systematic deviation caused by a single test condition, improve the accuracy of the calculation of the thermal conductivity of the material, and make the thermal conductivity of the material finally calculated closer to the actual thermal conductivity value. The embodiment of the present application improves the accuracy of the test results while ensuring the comprehensiveness of the grounding material performance test.

[0054] In an optional implementation, when the number of current value conditions is 2, the corresponding current values ​​include: 500A and 1kA. In an optional implementation, when the number of current value conditions is 3, the corresponding current values ​​include: 500A, 700A and 1kA. In an optional implementation, when the number of current value conditions is 3, the corresponding current values ​​include: 200A, 500A, 700A and 1kA.

[0055] In a possible implementation, the target current value conditions include: the current value is 1 kA, and the experimental time is 1 s;

[0056] Obtain the first temperature change record data of the grounding material to be tested during the current heating test process and the natural cooling test process under the target current value condition, including:

[0057] Obtain the first sub-temperature change record data of the grounding material to be tested during the through-current heating test at a current value of 1kA within 1s;

[0058] Stop the through-current heating. When the temperature of the grounding material to be tested drops to a value less than or equal to the set value compared with the ambient temperature, record the corresponding temperature change data after stopping the through-current heating as the second sub-temperature change recording data of the natural cooling test process.

[0059] Optionally, the setting value of the corresponding difference is 1°C, which is determined according to the experimental requirements and actual application scenarios. When the temperature of the grounding material to be tested drops to a difference between the temperature and the ambient temperature that is less than or equal to the setting value, the data recorded before this will be regarded as the second sub-temperature change record data of the natural cooling test process, which is convenient for accurately understanding the cooling characteristics of the material.

[0060] In a possible implementation, determining the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data includes:

[0061] According to the first temperature change record data, the radiation heat transfer equation corresponding to the through-flow heating test process is integrated to obtain a first integral result, and the instantaneous heat transfer equation corresponding to the natural cooling test process is integrated to obtain a second integral result;

[0062] The emissivity of the grounding material to be measured is determined according to the first integration result and the second integration result, and the specific heat capacity of the grounding material to be measured is determined according to the emissivity.

[0063] Among them, by integrating the heat transfer equation, we can deeply understand the dynamic process of temperature change, so as to more accurately determine the specific heat capacity and emissivity of the material.

[0064] In one possible implementation, when integrating the radiation heat transfer equation corresponding to the through-flow heating test process, the equation is as follows:

[0065]

[0066] When the transient heat transfer equation corresponding to the natural cooling test process is integrated, the equation is as follows:

[0067]

[0068] When determining the emissivity of the grounded material under test, the equation is as follows:

[0069]

[0070] Where V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, and c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, X1=T(t0+1)-T e , X2=T e +T(t0+1)-T(t0+1+t c ), ε is the emissivity, c p is the specific heat capacity.

[0071] In one embodiment, if Figure 1 As shown, when a thermocouple is arranged every 5 cm, and a total of 14 thermocouples are arranged, in the above equation, T is the average temperature of the 14 measuring points on the grounding material to be tested.

[0072] Take the case of using a 1kA power frequency current with a duration of 1s in step 301 to perform a current-through temperature rise test on a grounding anti-corrosion material as an example for explanation:

[0073] The instantaneous heat loss within 1 second of flow mainly comes from thermal radiation loss. The equation for instantaneous radiation heat transfer is:

[0074]

[0075] Where V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, and c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, The average temperature rise rate of multiple measuring points of the grounding material sample to be tested; is the cooling rate of the grounding material sample to be tested;

[0076] The instantaneous radiation heat transfer equation is integrated within the temperature rise duration of 1s as follows:

[0077]

[0078] Specific heat capacity c p It can be written as:

[0079]

[0080] Due to the emissivity ε and specific heat capacity c of the new grounding anti-corrosion material p Unknown, the emissivity ε must be determined before the specific heat c can be determined p , the power frequency current stops injecting after 1s, and enters the natural cooling stage. The heat loss is radiation loss. The instantaneous heat transfer equation of radiation loss is:

[0081]

[0082] For the natural cooling test process, the instantaneous radiation heat transfer equation is integrated to obtain the evolution relationship between emissivity and specific heat capacity. Specifically, the temperature change during the temperature recovery process is recorded until the difference between the temperature rise and the ambient temperature is within 1°C. It is considered that the temperature has fully recovered at the time t c , the transient heat transfer equation is integrated as follows:

[0083]

[0084] Therefore

[0085]

[0086] Combine the two specific heat capacities c p Equations (6) and (9) are solved to obtain the emissivity ε of the grounding material to be tested:

[0087]

[0088] Where V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, and c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, X1=T(t0+1)-T e , X2=T e +T(t0+1)-T(t0+1+t c ), ε is the emissivity, c p is the specific heat capacity;

[0089] Substituting equation (10) into equation (9) yields the specific heat capacity c p , and record the emissivity ε and specific heat capacity c p The solution result of .

[0090] In a possible implementation, second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions are obtained respectively, including:

[0091] For two or more different current setting conditions, perform the following steps respectively:

[0092] Under a set current value, record the temperature change rate per unit time;

[0093] When the temperature change rate is less than the first set change rate, stop injecting current and record the sub-temperature change record data corresponding to the temperature rise process;

[0094] After the injection of current is stopped, when the temperature change rate is less than the second set change rate, the sub-temperature change record data corresponding to the cooling process is recorded;

[0095] Correspondingly, the second temperature change record data corresponding to the temperature rise process and the cooling process includes sub-temperature change record data corresponding to the temperature rise process under each set current value condition and sub-temperature change record data corresponding to the cooling process.

[0096] Optionally, the first setting change rate and the second setting change rate are the same. In a possible implementation, the first setting change rate and the second setting change rate are 1° C. / s.

[0097] In a possible implementation, according to the second temperature change record data corresponding to each current value, the stage thermal conductivity corresponding to the temperature rise process and the cooling process is calculated respectively, including:

[0098] The instantaneous thermal balance equation of the grounding material to be tested during the temperature rise process is:

[0099]

[0100] When the temperature change rate is less than the first set change rate, the instantaneous heat balance equation is integrated as follows:

[0101]

[0102] The thermal conductivity of the stage corresponding to the temperature rise process is:

[0103]

[0104] The instantaneous heat balance equation of the grounding material to be tested during the cooling process is:

[0105]

[0106] When the temperature change rate is less than the second set change rate, the instantaneous heat balance equation is integrated as follows:

[0107]

[0108] The thermal conductivity of the cooling process is:

[0109]

[0110] Among them, k h k is the thermal conductivity during the temperature rise process; c is the thermal conductivity during the cooling process; t3 is the moment when the current injection is stopped; t4 is the moment when the temperature change rate is less than the second set change rate; V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, ε is the emissivity, c p is the specific heat capacity.

[0111] In different embodiments, the manner of determining the thermal conductivity of the material is different according to the thermal conductivity of each stage.

[0112] In a possible implementation, the thermal conductivity of the material is determined according to the thermal conductivity of each stage, including:

[0113] Calculate the average value of the stage thermal conductivity corresponding to the temperature rise process and the cooling process at the same set current value, and record the average value of the stage thermal conductivity corresponding to each set current value as the material thermal conductivity.

[0114] Among them, the calculation formula of the material thermal conductivity corresponding to the same set current value is as follows:

[0115] k=0.5(k c +k h ) (17);

[0116] Where k is the average thermal conductivity, k h k is the thermal conductivity during the temperature rise process; c is the thermal conductivity during cooling.

[0117] In this embodiment, since the thermal conductivity of the material is affected by many factors, including temperature, pressure and current density, the average value of the stage thermal conductivity corresponding to each set current value is recorded as the thermal conductivity of the material. This can not only understand the thermal conductivity of the material of the grounding material to be tested, but also analyze the difference in the thermal conductivity of the material under different set current values.

[0118] In another possible implementation, the thermal conductivity of the material is determined according to the thermal conductivity of each stage, including:

[0119] Calculate the average value of the thermal conductivity of the stage corresponding to the temperature rise process of each set current value, and the average value of the thermal conductivity of the stage corresponding to the cooling process of each set current value, and record the average value of the temperature rise process and the average value of the cooling process.

[0120] Take the setting of the current value to 3 as an example. The material thermal conductivity calculation formula is as follows:

[0121]

[0122] Among them, k h k is the thermal conductivity during the temperature rise process; c is the thermal conductivity during cooling; k hi k is the thermal conductivity during the temperature rise process of the i-th set current value; ci is the thermal conductivity during the cooling process for the i-th set current value.

[0123] In this embodiment, the average value of the temperature rise process and the average value of the cooling process under different current value conditions are recorded, so as to eliminate the influence of temperature change on the calculation result of the thermal conductivity of the material.

[0124] In other possible implementations, the thermal conductivity of the material is determined according to the thermal conductivity of each stage, including:

[0125] Calculate the average value of the thermal conductivity of the stages corresponding to the temperature rise process and the cooling process of the same set current value, and record the average value of the thermal conductivity of the stages corresponding to each set current value as the thermal conductivity of the material; and,

[0126] Calculate the average value of the thermal conductivity of the stage corresponding to the temperature rise process of each set current value, and the average value of the thermal conductivity of the stage corresponding to the cooling process of each set current value, and record the average value of the temperature rise process and the average value of the cooling process.

[0127] In a specific embodiment, the specific process of determining the thermal conductivity of a material is as follows: Figure 4 As shown, the following is an example in which the set current values ​​are 500A, 700A and 1000A respectively; the first set change rate and the second set change rate are 1°C / s.

[0128] correspond Figure 4 , the temperature rise curves and applied power curves of the three test currents Figure 5a and Figure 5b As shown. Figure 5b As shown, the test current is fed in from time point t2 and is cut off at time point t3. Correspondingly, Figure 5a As shown, the temperature rise process is from time point t2 to time point t3, and the cooling process is from time point t3 to time point t4.

[0129] In a possible implementation, the method further includes:

[0130] Obtain voltage measurement data and current measurement data corresponding to the temperature rise process and the cooling process under two or more different set current value conditions;

[0131] Deducing the impedance of the grounding material to be tested based on the voltage measurement data and the current measurement data;

[0132] The current carrying capacity of the grounding material to be tested is deduced based on the impedance deduction results.

[0133] In a possible implementation, the impedance Z of the new grounding anti-corrosion material is deduced from the voltage measurement data and the current measurement data corresponding to the temperature rise process and the cooling process as follows:

[0134]

[0135] In the formula, is the phasor of the voltage measurement, is the phasor of the current measurement.

[0136] Deducing the current carrying capacity I of the grounding material to be tested based on the impedance deduction results rms as follows:

[0137] The duration of a short circuit fault in a power system is generally less than 0.5s, so all the heat generated by the fault current will be converted into a temperature increase of the conductor. At this time, the effect of conductor heat conduction can be ignored, so there is

[0138]

[0139] Where Q is the heat generated by the fault current, Re is the operation of taking the real part of the complex number, and T max is the maximum allowable temperature rise of the new grounding anti-corrosion material. Therefore, the current carrying capacity of the new grounding anti-corrosion material is rms for

[0140]

[0141] In a possible implementation, the method for testing the performance of a grounding material further includes:

[0142] Output the emissivity, specific heat capacity, material thermal conductivity and current carrying capacity of the grounding material to be tested.

[0143] The above embodiments are described in detail for each step. In a specific embodiment, the overall process of the method for testing the performance of grounding materials is as follows: Figure 6 As shown, the specific steps include:

[0144] Step S1: Build a new grounding anti-corrosion material flow temperature rise test system in a semi-adiabatic environment.

[0145] Step S2: Conduct an emissivity-specific heat capacity test on the new grounding anti-corrosion material to obtain the emissivity and specific heat capacity of the new grounding anti-corrosion material.

[0146] Step S3: Conduct a long-term current-through temperature rise relaxation test on the new grounding anti-corrosion material in a semi-adiabatic environment at currents of 500A, 700A, and 1000A, respectively, to obtain the thermal conductivity k of the new grounding anti-corrosion material.

[0147] Step S4: Obtain the flow capacity parameters of the new grounding anti-corrosion material.

[0148] Step S5: outputting the emissivity, specific heat capacity, thermal conductivity and flow capacity parameters of the new grounding anti-corrosion material.

[0149] Wherein, step S1 specifically includes the following steps:

[0150] Build an adjustable power frequency cross-flow process-controlled current source, the output current range is 1~1kA;

[0151] Build a test simulation environment;

[0152] Build a voltage-current-temperature measurement system;

[0153] Complete the wiring of the new grounding anti-corrosion material flow temperature rise system in a semi-adiabatic environment.

[0154] Step S2 specifically includes the following steps:

[0155] Use 1kA power frequency current test for 1s, conduct current through temperature rise test, and record the temperature rise process;

[0156] By integrating the radiation heat transfer equation of the temperature rise process within 1 second, we can obtain the relationship between specific heat capacity and emissivity①, which is the above equation (6);

[0157] Cool the new grounding anti-corrosion material until the temperature rise is within 1°C of the ambient temperature, and record the temperature changes during the temperature recovery process;

[0158] By integrating the radiation heat transfer equation of the temperature recovery process, we can obtain the relationship between specific heat capacity and emissivity②, which is the above equation (9);

[0159] By combining the relationship ① and relationship ② between specific heat capacity and emissivity, we can obtain the emissivity of the new grounding anti-corrosion material, and then its specific heat capacity.

[0160] Step S3 specifically includes the following steps:

[0161] The current source starts to supply the test current at the ambient temperature at time t2 and continues to heat the sample, and the entire temperature rise process is recorded;

[0162] During the heating process, if the temperature rise within 1s is less than 1°C, it is considered that the conductor enters the steady-state process of temperature rise, and the time t3 of the steady-state temperature is recorded, from which the thermal conductivity of the temperature rise process can be obtained;

[0163] Stop the power output from time t3 and record the temperature change during the entire cooling process. If the temperature drops less than 1°C within 1s, the conductor is considered to be completely cooled. Record the time t4 when the complete cooling process begins and calculate the thermal conductivity of the cooling process.

[0164] The thermal conductivity of the temperature rise process and the thermal conductivity of the cooling process are averaged to obtain the average thermal conductivity.

[0165] Step S4 specifically includes the following steps:

[0166] The impedance of the new grounding anti-corrosion material is deduced from the voltage and current measurement data in step 3;

[0167] When a short circuit fault occurs, it is assumed that all the heat generated by the fault current is converted into an increase in the conductor temperature, and the effect of conductor heat conduction is ignored, thereby deriving the current carrying capacity of the new grounding anti-corrosion material.

[0168] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0169] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0170] Figure 7 The schematic diagram of the structure of the device for testing the performance of grounding materials provided by the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0171] An acquisition module 701 is used to acquire first temperature change record data of the grounding material to be tested during a current heating test process and a natural cooling test process under a target current value condition;

[0172] A determination module 702 is used to determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data;

[0173] The acquisition module 701 is further used to respectively acquire second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions;

[0174] The determination module 702 is further used to calculate the stage thermal conductivity corresponding to the temperature rise process and the cooling process respectively according to the second temperature change record data corresponding to each current value, and determine the thermal conductivity of the material according to the thermal conductivity of each stage.

[0175] In a possible implementation, the determination module 702 is specifically configured to:

[0176] According to the first temperature change record data, the radiation heat transfer equation corresponding to the through-flow heating test process is integrated to obtain a first integral result, and the instantaneous heat transfer equation corresponding to the natural cooling test process is integrated to obtain a second integral result;

[0177] The emissivity of the grounding material to be tested is determined according to the first integration result and the second integration result, and the specific heat capacity of the grounding material to be tested is determined according to the emissivity.

[0178] In a possible implementation, the target current value conditions include: the current value is 1 kA, and the experimental time is 1 s;

[0179] The determination module 702 is specifically configured to:

[0180] Obtain the first sub-temperature change record data of the grounding material to be tested during the through-current heating test at a current value of 1kA within 1s;

[0181] Stop the through-current heating. When the temperature of the grounding material to be tested drops to a value less than or equal to the set value compared with the ambient temperature, record the corresponding temperature change data after stopping the through-current heating as the second sub-temperature change recording data of the natural cooling test process.

[0182] In a possible implementation, the acquisition module 702 is specifically configured to:

[0183] Under a set current value, record the temperature change rate per unit time;

[0184] When the temperature change rate is less than the first set change rate, stop injecting current and record the sub-temperature change record data corresponding to the temperature rise process;

[0185] After the injection of current is stopped, when the temperature change rate is less than the second set change rate, the sub-temperature change record data corresponding to the cooling process is recorded;

[0186] Correspondingly, the second temperature change record data corresponding to the temperature rise process and the cooling process includes sub-temperature change record data corresponding to the temperature rise process under each set current value condition and sub-temperature change record data corresponding to the cooling process.

[0187] In a possible implementation, the determination module 702 is specifically configured to:

[0188] Calculate the average value of the thermal conductivity of the stages corresponding to the temperature rise process and the cooling process of the same set current value, and record the average value of the thermal conductivity of the stages corresponding to each set current value as the thermal conductivity of the material; or,

[0189] Calculate the average value of the thermal conductivity of the stage corresponding to the temperature rise process of each set current value, and the average value of the thermal conductivity of the stage corresponding to the cooling process of each set current value, and record the average value of the temperature rise process and the average value of the cooling process.

[0190] In a possible implementation, the current values ​​corresponding to the set current value conditions include: 500A, 700A and 1kA.

[0191] In this embodiment, by setting a target current value condition and two or more different set current value conditions, the specific heat capacity, emissivity and thermal conductivity of the grounding material to be tested are measured respectively. The specific heat capacity reflects the ability of the material to absorb or release heat, while the emissivity describes the efficiency of the material to emit energy in the form of radiation. Therefore, setting the target current value condition in a targeted manner can improve the accuracy of the calculation of specific heat capacity and emissivity. The thermal conductivity of the material is affected by many factors, including temperature, pressure, and current density. Therefore, measuring and calculating the thermal conductivity of the material under two or more different set current value conditions can avoid the systematic deviation caused by a single test condition, improve the accuracy of the calculation of the thermal conductivity of the material, and make the thermal conductivity of the material finally calculated closer to the actual thermal conductivity value. The embodiment of the present application improves the accuracy of the test results while ensuring the comprehensiveness of the grounding material performance test.

[0192] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0193] Those of ordinary skill in the art will appreciate that the templates, units, and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0194] If the module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned method embodiments for testing the performance of grounding materials can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium.

[0195] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for testing the performance of a grounding material, characterized in that: include: Obtaining first temperature change record data of the grounding material to be tested during the through-current heating test process and the natural cooling test process under the condition of the target current value; Determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data; Respectively obtain the second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions; According to the second temperature change record data corresponding to each current value, the stage thermal conductivity corresponding to the temperature rise process and the cooling process is calculated respectively, and the material thermal conductivity is determined according to the thermal conductivity of each stage.

2. The method for testing the performance of grounding materials according to claim 1, characterized in that: The step of determining the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data comprises: According to the first temperature change record data, the radiation heat transfer equation corresponding to the through-flow heating test process is integrated to obtain a first integration result, and the instantaneous heat transfer equation corresponding to the natural cooling test process is integrated to obtain a second integration result; The emissivity of the grounding material to be measured is determined according to the first integration result and the second integration result, and the specific heat capacity of the grounding material to be measured is determined according to the emissivity.

3. The method for testing the performance of grounding materials according to claim 2, characterized in that: When integrating the radiation heat transfer equation corresponding to the through-flow heating test process, the equation is as follows: When the transient heat transfer equation corresponding to the natural cooling test process is integrated, the equation is as follows: When determining the emissivity of the grounded material under test, the equation is as follows: Where V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, and c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, X1=T(t0+1)-T e , X2=T e +T(t0+1)-T(t0+1+t c ), ε is the emissivity, and cp is the specific heat capacity.

4. The method for testing the performance of grounding materials according to claim 1, characterized in that: The target current value conditions include: the current value is 1kA and the experimental time is 1s; The step of obtaining first temperature change record data of the grounding material to be tested during the current heating test process and the natural cooling test process under the target current value condition includes: Obtain the first sub-temperature change record data of the grounding material to be tested during the through-current heating test at a current value of 1kA within 1s; Stop the through-current heating. When the temperature of the grounding material to be tested drops to a value less than or equal to the set value compared with the ambient temperature, record the corresponding temperature change data after stopping the through-current heating as the second sub-temperature change recording data of the natural cooling test process.

5. The method for testing the performance of grounding materials according to claim 1, characterized in that: The method of respectively obtaining the second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions includes: For two or more different current setting conditions, perform the following steps respectively: Under a set current value, record the temperature change rate per unit time; When the temperature change rate is less than the first set change rate, stop injecting current and record the sub-temperature change record data corresponding to the temperature rise process; After the injection of current is stopped, when the temperature change rate is less than the second set change rate, the sub-temperature change record data corresponding to the cooling process is recorded; Correspondingly, the second temperature change record data corresponding to the temperature rise process and the cooling process includes sub-temperature change record data corresponding to the temperature rise process under each set current value condition and sub-temperature change record data corresponding to the cooling process.

6. The method for testing the performance of grounding materials according to claim 5, characterized in that: The step of calculating the thermal conductivity of the stages corresponding to the temperature rise process and the cooling process respectively according to the second temperature change record data corresponding to each current value includes: The instantaneous thermal balance equation of the grounding material to be tested during the temperature rise process is: When the temperature change rate is less than the first set change rate, the instantaneous heat balance equation is integrated as follows: The thermal conductivity of the stage corresponding to the temperature rise process is: The instantaneous heat balance equation of the grounding material to be tested during the cooling process is: When the temperature change rate is less than the second set change rate, the instantaneous heat balance equation is integrated as follows: The thermal conductivity of the cooling process is: Among them, k h k is the thermal conductivity during the temperature rise process; c is the thermal conductivity during the cooling process; t3 is the moment when the current injection is stopped; t4 is the moment when the temperature change rate is less than the second set change rate; V is the voltage measurement value on the grounding material to be tested, I is the current measurement value through the grounding material to be tested, c p is the specific heat capacity of the grounding material to be tested, m is the mass of the grounding material to be tested with a length of L2, ε is the emissivity of the grounding material to be tested, σ is the Stefan-Bolzmann constant, A is the effective surface area of ​​the grounding material to be tested with a length of L2, T is the average temperature of multiple measuring points on the grounding material to be tested, T e is the ambient temperature, ε is the emissivity, c p is the specific heat capacity.

7. The method for testing the performance of grounding materials according to claim 1, characterized in that: Determining the thermal conductivity of the material according to the thermal conductivity of each stage includes: Calculate the average value of the thermal conductivity of the stages corresponding to the temperature rise process and the cooling process of the same set current value, and record the average value of the thermal conductivity of the stages corresponding to each set current value as the thermal conductivity of the material; or, Calculate the average value of the thermal conductivity of the stage corresponding to the temperature rise process of each set current value, and the average value of the thermal conductivity of the stage corresponding to the cooling process of each set current value, and record the average value of the temperature rise process and the average value of the cooling process.

8. The method for testing the performance of grounding materials according to claim 1, characterized in that: The current values ​​corresponding to the set current value conditions include: 500A, 700A and 1kA.

9. A device for testing the performance of grounding materials, characterized in that: include: An acquisition module is used to acquire first temperature change record data of the grounding material to be tested during a current heating test process and a natural cooling test process under a target current value condition; A determination module, used to determine the specific heat capacity and emissivity of the grounding material to be tested according to the first temperature change record data; The acquisition module is also used to respectively acquire second temperature change record data corresponding to the temperature rise process and the cooling process of the grounding material to be tested under two or more different set current value conditions; The determination module is also used to calculate the stage thermal conductivity corresponding to the temperature rise process and the cooling process respectively according to the second temperature change record data corresponding to each current value, and determine the thermal conductivity of the material according to the thermal conductivity of each stage.

10. A system for testing the performance of grounding materials, characterized in that: include: The device for testing the performance of grounding materials as described in claim 9, the industrial frequency constant current power supply, the square convection shielding box, the current detection unit, the voltage detection unit, the thermocouple measurement array and the corresponding multi-channel temperature recorder; the industrial frequency constant current power supply is an adjustable industrial frequency constant current source; Wherein, each thermocouple in the thermocouple measurement array is arranged on the surface of the test conductor inside the square convection shielding box; The thermocouples are arranged according to set intervals; The industrial frequency constant current power supply, the current detection unit and the voltage detection unit are connected to the grounding material to be tested and the device for testing the performance of the grounding material through current wire clamps.

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