A method, device and storage medium for monitoring temperature distribution of deep well grounding electrode

Abstract

The present invention relates to the technical field of power system grounding, and in particular to a method, device and storage medium for monitoring the temperature distribution of a deep well grounding electrode, including respectively constructing two deep well DC grounding electrodes arranged at intervals; performing a rated current flow temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation modes to obtain the rated current flow duration; obtaining a rated time constant according to the rated temperature change data and the rated current flow duration during the rated current flow natural cooling process; performing an overload flow temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation modes to obtain the overload flow duration; obtaining an overload time constant according to the overload temperature change data and the overload flow duration during the overload flow natural cooling process; and evaluating the thermal performance of the deep well DC grounding electrode based on the rated time constant and the overload time constant. The present invention can comprehensively and accurately evaluate the thermal performance of the deep well DC grounding electrode during operation, and ensure the safe operation of the deep well DC grounding electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of power system grounding, and in particular to a method, device and storage medium for monitoring temperature distribution of a deep well grounding electrode. Background Art

[0002] As an indispensable component of DC transmission projects, DC grounding electrodes primarily clamp overvoltages at the neutral point on the valve side of converter stations and provide a guiding path for earth return currents. In traditional DC transmission projects, horizontally buried DC grounding electrodes are widely used due to their mature technology. However, with the increasing complexity of engineering construction environments, the conditions for horizontally laying DC grounding electrodes are becoming increasingly difficult to meet. Vertical grounding electrodes, due to their small footprint and strong terrain adaptability, have become an effective solution to address space constraints.

[0003] However, vertical grounding electrodes also face some technical difficulties. Vertical grounding electrodes are usually composed of multiple deep-well sub-electrodes, and their temperature rise problem is more prominent and difficult to effectively control. At the same time, since vertical grounding electrodes are usually composed of multiple deep-well sub-electrodes, the length of these deep-well sub-electrodes can reach several meters or even tens of meters, and the commonly used high-silicon iron electrode products are limited in length, multiple unit electrodes must be connected through drainage cables to achieve the total length required by the design. Although this connection method ensures the length of the electrode, it also increases the complexity of the system. At the same time, due to the closed environment of the deep well, the gas generated during the electrolysis process is difficult to be discharged naturally, and an additional exhaust pipe is required to solve this problem. In addition, the existing vertical grounding electrodes have significant deficiencies in actual operation. Since the unit electrodes are long and are usually buried deep underground, it is difficult to directly install temperature sensors to monitor the operating status of the grounding electrodes in real time. This results in the temperature rise of the DC grounding electrode cannot be effectively monitored, increasing the risk of system operation. This monitoring blind spot not only affects the operation and maintenance personnel's accurate judgment of the grounding electrode status, but also increases the possibility of failure caused by excessive temperature.

[0004] In summary, existing vertical grounding electrodes have many problems in temperature rise control and temperature monitoring. There is an urgent need for a new technology that can effectively solve these problems to improve the safety, reliability and operating efficiency of DC grounding electrodes. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method, device and storage medium for monitoring the temperature distribution of a deep well grounding electrode.

[0006] In a first aspect, the present invention provides a method for monitoring the temperature distribution of a deep well ground electrode, the method comprising the following steps:

[0007] According to the operation requirements of the DC grounding electrode, two deep well locations arranged at intervals are selected within the DC grounding electrode site, and deep well DC grounding electrodes are respectively constructed at the deep well locations;

[0008] Performing a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration;

[0009] After the rated current flow temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the rated temperature change data during the natural cooling process of the rated current flow, and the rated time constant under the rated current condition is calculated based on the rated temperature change data and the rated current flow duration;

[0010] Perform an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the duration of the overload current;

[0011] After the overload current temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the overload temperature change data during the overload current natural cooling process. The overload time constant under the overload current condition is calculated based on the overload temperature change data and the duration of the overload current.

[0012] The thermal performance of the deep well DC grounding electrode during operation is evaluated based on the rated time constant and the overload time constant.

[0013] In a further embodiment, each of the deep well DC grounding electrodes is composed of three hollow steel pipes of equal length buried at different distances underground, and the deep well DC grounding electrode is connected to each hollow steel pipe by coke filling;

[0014] Thermocouples are evenly distributed around the bottom of the deep well DC grounding electrode, and a pair of thermocouples are distributed at different distances from the bottom of the deep well DC grounding electrode. Thermocouples are arranged at intervals in the three sections of hollow steel pipes inside the deep well DC grounding electrode. All thermocouples are connected to a temperature patrol meter in sequence so that the temperature patrol meter can monitor the temperature changes of the thermocouples in real time.

[0015] In a further embodiment, the positive and negative pole operation mode is an operation mode in which one deep well DC grounding pole is a positive pole and the other deep well DC grounding pole is a negative pole.

[0016] In a further embodiment, the through-current loaded in the rated current through-current temperature rise test is twice the ratio of the DC transmission rated current to the number of deep well DC grounding electrodes.

[0017] In a further embodiment, the step of calculating the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration includes:

[0018] During the natural cooling process after the rated current flow temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is taken as the rated cooling end time;

[0019] Obtaining a rated cooling recovery time according to a difference between the rated current flow duration and the rated cooling end time;

[0020] Calculating the difference between the underground ambient temperature and the temperature at the end of the rated cooling to obtain the rated cooling temperature difference, and calculating the difference between the maximum temperature during the rated current flow duration and the underground ambient temperature to obtain the rated current flow temperature rise;

[0021] Obtaining a rated temperature change ratio according to a ratio of the rated cooling temperature difference to the natural logarithm of the rated through-flow temperature rise;

[0022] A rated time constant under rated current conditions is obtained according to the rated cooling recovery time and the rated temperature change rate.

[0023] In a further embodiment, the through-current loaded in the overload through-current temperature rise test is twice the ratio of the product of the DC transmission rated current and the DC transmission overload current multiple to the number of deep well DC grounding electrodes.

[0024] In a further embodiment, the step of calculating the overload time constant under the overload current condition based on the overload temperature change data and the overload current duration includes:

[0025] During the natural cooling process after the overload current temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is regarded as the end time of overload cooling;

[0026] Obtaining an overload cooling recovery time based on a difference between the duration of the overload current flow and the end time of the overload cooling;

[0027] Calculating the difference between the underground ambient temperature and the temperature at the end of the overload cooling to obtain the overload cooling temperature difference, and calculating the difference between the maximum temperature during the overload flow duration and the underground ambient temperature to obtain the overload flow temperature rise;

[0028] Obtaining an overload temperature change ratio according to a ratio of the overload cooling temperature difference to the natural logarithm of the overload flow temperature rise amplitude;

[0029] An overload time constant under an overload current condition is obtained according to the overload cooling recovery time and the overload temperature change ratio.

[0030] In a further embodiment, the step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant includes:

[0031] Calculating a deep well overload coefficient based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple;

[0032] Calculating a ratio between the rated time constant and a preset rated time design value to obtain a rated time constant ratio;

[0033] Calculating a ratio between the overload time constant and a preset overload time design value to obtain an overload time constant ratio;

[0034] Calculating the rated current limit temperature rise of the deep well DC grounding electrode according to the rated time constant and the rated current flow duration;

[0035] Calculating the overload limit temperature increase of the deep well DC grounding electrode according to the overload time constant and the duration of the overload current flow;

[0036] Calculating a rated-to-overload limit temperature increase ratio according to the rated current limit temperature increase amplitude and the overload limit temperature increase amplitude;

[0037] defining the deep well overload coefficient, the rated time constant ratio, the overload time constant ratio, and the rated-overload limit temperature rise ratio as performance evaluation coefficients, and determining a preset thermal performance qualified threshold interval for each performance evaluation coefficient;

[0038] The performance evaluation coefficient is used to evaluate the thermal performance of the deep well DC grounding electrode during operation, and when all the performance evaluation coefficients meet the preset thermal performance qualified threshold range, the thermal performance of the deep well DC grounding electrode is determined to be qualified.

[0039] In a further embodiment, the step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant further includes:

[0040] The rated thermal resistance of the deep well DC grounding electrode is calculated based on the rated current limit temperature rise amplitude, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the rated current through-current temperature rise test;

[0041] The rated thermal capacity of the deep well DC grounding electrode is obtained according to the ratio of the rated thermal resistance of the deep well DC grounding electrode and the rated time constant;

[0042] The overload thermal resistance of the deep well DC grounding electrode is calculated based on the overload limit temperature rise amplitude, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the overload through-current temperature rise test;

[0043] Obtaining the overload thermal capacity of the deep well DC grounding electrode according to the ratio of the overload thermal resistance of the deep well DC grounding electrode to the overload time constant;

[0044] When judging that the thermal performance of the deep well DC grounding electrode is qualified, the temperature response characteristics of the deep well DC grounding electrode under different operating conditions are determined according to the rated thermal resistance, rated thermal capacity, overload thermal resistance and overload thermal capacity;

[0045] According to the temperature response characteristics and the soil heat dissipation performance of the deep well DC grounding electrode, the continuous operation capability of the deep well DC grounding electrode is evaluated using a numerical simulation method.

[0046] In a further embodiment, the soil heat dissipation performance evaluation process of the deep well DC grounding electrode includes:

[0047] At the end of the rated current flow temperature rise test, obtain the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple from the preset thermocouple arrangement position;

[0048] At the end of the overload current temperature rise test, the overload current maximum temperature rise thermocouple and the overload current minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions;

[0049] Comparing the maximum temperature rise thermocouple at the rated current flow and the maximum temperature rise thermocouple at the overload current flow to determine whether it is the maximum temperature rise point, and obtaining a maximum temperature rise detection result;

[0050] Comparing the rated current minimum temperature rise thermocouple with the overload minimum temperature rise thermocouple to determine whether it is the minimum temperature rise point, and obtaining a minimum temperature rise detection result;

[0051] The temperature rise distribution law is analyzed based on the maximum temperature rise detection results and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated.

[0052] In a second aspect, the present invention provides a deep well ground electrode temperature distribution monitoring device, the device comprising:

[0053] The grounding electrode layout module is used to select two deep well locations arranged at intervals within the DC grounding electrode site according to the DC grounding electrode operation requirements, and to construct deep well DC grounding electrodes at the deep well locations respectively;

[0054] A rated temperature rise test module is used to perform a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration;

[0055] A rated temperature rise analysis module is used to naturally cool the deep-well DC grounding electrode after the rated current flow temperature rise test is completed, obtain the rated temperature change data during the natural cooling process of the rated current flow, and calculate the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration;

[0056] An overload temperature rise test module is used to perform an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the duration of the overload current;

[0057] An overload temperature rise analysis module is used to naturally cool the deep well DC grounding electrode after the overload current temperature rise test is completed, obtain overload temperature change data during the natural cooling process of the overload current, and calculate the overload time constant under the overload current condition based on the overload temperature change data and the duration of the overload current;

[0058] The grounding electrode evaluation module is used to evaluate the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant.

[0059] In a third aspect, the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0060] The present invention provides a method, device and storage medium for monitoring the temperature distribution of a deep well grounding electrode. The method selects two deep well points arranged at intervals within the DC grounding electrode site according to the operation requirements of the DC grounding electrode, and constructs deep well DC grounding electrodes respectively; performs a rated current flow temperature rise test on the deep well DC grounding electrode under a preset positive and negative pole operation mode to obtain the rated current flow duration; naturally cools the deep well DC grounding electrode to obtain rated temperature change data during the rated current flow natural cooling process, and obtains the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration; performs an overload flow temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the overload flow duration; naturally cools the deep well DC grounding electrode to obtain overload temperature change data during the overload flow natural cooling process, and obtains the overload time constant under the overload current condition based on the overload temperature change data and the overload flow duration; and evaluates the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant. Compared with the existing technology, this method can comprehensively and accurately evaluate the thermal performance of deep-well DC grounding electrodes during operation by arranging thermocouple temperature distribution monitoring in deep-well grounding electrodes and combining rated and overload current tests, thereby ensuring the safety and reliability of deep-well DC grounding electrodes under complex operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a flow chart of a method for monitoring temperature distribution of a deep well grounding electrode provided by an embodiment of the present invention;

[0062] Figure 2 This is a top view of the spacing arrangement of deep well DC grounding electrodes provided by an embodiment of the present invention;

[0063] Figure 3 This is a top view of a deep well DC grounding electrode provided by an embodiment of the present invention;

[0064] Figure 4 This is a cross-sectional view of the interior of a deep well DC grounding electrode provided by an embodiment of the present invention;

[0065] Figure 5 This is a schematic diagram of the in-well feeder cable connection of the deep well DC grounding electrode provided by an embodiment of the present invention;

[0066] Figure 6 Schematic diagram of the arrangement of thermocouples in a deep well DC grounding electrode according to an embodiment of the present invention;

[0067] Figure 7 This is a wiring diagram for a current-through temperature rise test in a positive and negative electrode operation mode provided by an embodiment of the present invention;

[0068] Figure 8 This is a block diagram of a deep well ground electrode temperature distribution monitoring device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0069] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings. The embodiments are provided for illustrative purposes only and are not to be construed as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of protection of the present invention. Many changes may be made to the present invention without departing from the spirit and scope of the present invention.

[0070] refer to Figure 1 , the embodiment of the present invention provides a method for monitoring the temperature distribution of a deep well grounding electrode, such as Figure 1 As shown, the method includes the following steps:

[0071] S1. According to the operation requirements of the DC grounding electrode, two deep well locations arranged at intervals are selected within the DC grounding electrode site, and deep well DC grounding electrodes are constructed at the deep well locations.

[0072] In a specific embodiment, Figure 2 As shown, in this embodiment, two deep well sites 40 meters apart are selected within the DC grounding electrode site, and two deep well DC grounding electrodes with a depth of 35 meters are constructed at the deep well sites. In this embodiment, the two deep well DC grounding electrodes are named deep well DC grounding electrode W1 and deep well DC grounding electrode W2 respectively. The deep well DC grounding electrode W1 and the deep well DC grounding electrode W2 have the same structure. The wellhead outer diameter of the two deep well DC grounding electrodes is 120 mm, forming a 35-meter deep well grounding electrode system with temperature distribution monitoring function. In this embodiment, three sections of 10-meter-long hollow steel pipes are arranged inside each deep well DC grounding electrode, as shown in FIG. Figure 3 As shown, the diameter of the hollow steel pipe is 100 mm and the wall thickness is 10 mm. Three sections of the hollow steel pipe are buried in the depth ranges of 5 meters to 15 meters, 15 meters to 25 meters, and 25 meters to 30 meters underground respectively. Figure 4 As shown, hollow steel pipes W1S1, W1S2 and W1S3 constitute the main part of the deep well DC grounding electrode W1 in the well, and hollow steel pipes W2S1, W2S2 and W2S3 constitute the main part of the deep well DC grounding electrode W2 in the well. The deep well DC grounding electrode and each section of the hollow steel pipe are connected by coke filling. The gaps between the deep well DC grounding electrode W1 and the hollow steel pipes W1S1, W1S2 and W1S3 are filled with coke. Similarly, the gaps between the deep well DC grounding electrode W2 and the hollow steel pipes W2S1, W2S2 and W2S3 are filled with coke to enhance electrical conductivity and thermal conductivity.

[0073] like Figure 5As shown, the three sections of hollow steel pipes inside the deep well DC grounding electrode W1 and the deep well DC grounding electrode W2 are connected to the busbar at the wellhead through welding points and feeder cables to form a complete electrical connection path. Specifically, the hollow steel pipe W1S1, the hollow steel pipe W1S2 and the hollow steel pipe W1S3 are connected to the busbar B1 through welding points and feeder cables, and the hollow steel pipes W2S1, the hollow steel pipe W2S2 and the hollow steel pipe W2S3 are connected to the busbar B2 through welding points and feeder cables. When performing a current flow test in this embodiment, it is necessary to connect the busbar B1 and the busbar B2 in series with the test power supply.

[0074] like Figure 6 As shown, in this embodiment, four thermocouples are evenly arranged around the bottom of each deep well DC grounding electrode, and then a pair of thermocouples are arranged at different positions of 0.25 meters, 0.5 meters, 0.75 meters and 1 meter from the bottom of the deep well (a total of 8). In the remaining three sections of hollow steel pipe inside the deep well, in this embodiment, a thermocouple is set every 1 meter. The thermocouple arrangement form in the deep well DC grounding electrode W1 and the deep well DC grounding electrode W2 are the same. This embodiment takes the W1 deep well as an example to illustrate the arrangement of the thermocouples. Four thermocouples are evenly arranged around the bottom of the hollow steel pipe W1S1 (z = 0 meters), and four pairs of thermocouples are arranged at z = 0.25 meters, 0.5 meters, 0.75 meters, and 1 meter, a total of 8 thermocouples, z represents the depth of the deep well. A thermocouple is arranged at intervals of 1 meter for the remaining parts of the hollow steel pipe W1S1, the hollow steel pipe W1S2 and the hollow steel pipe W1S3. In the entire system, there are a total of 82 thermocouples in the deep well DC grounding electrode W1 and the deep well DC grounding electrode W2. Through the arrangement of the thermocouples, comprehensive monitoring and performance evaluation of the DC grounding electrode temperature distribution can be achieved. These thermocouples are connected to a temperature patrol meter in a predetermined order. The temperature patrol meter continuously records the temperature changes of the thermocouples at a sampling rate of 10 Hz. Before the current test, this embodiment can record the initial temperature of all thermocouples through the temperature patrol meter and monitor the temperature changes during the test.

[0075] To evaluate the performance of deep-well DC grounding electrodes, this embodiment conducts rated current temperature rise-natural cooling tests and overload current temperature rise-natural cooling tests to determine parameters such as the overload time constant ratio, rated time constant ratio, maximum temperature rise position number, minimum temperature rise position number, "rated-overload" limit temperature rise ratio, thermal resistance, and thermal capacitance. These parameters are used to comprehensively evaluate the performance of the DC grounding electrode, thereby comprehensively analyzing the thermal properties of the grounding electrode.

[0076] S2. Perform a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration.

[0077] S3. After the rated current flow temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the rated temperature change data of the rated current flow natural cooling process, and the rated time constant under the rated current condition is calculated based on the rated temperature change data and the rated current flow duration.

[0078] In some embodiments, the step of calculating the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration includes:

[0079] During the natural cooling process after the rated current flow temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is taken as the rated cooling end time;

[0080] The rated cooling recovery time is obtained based on the difference between the rated current flow duration and the rated cooling end time;

[0081] Calculate the difference between the ground ambient temperature and the temperature at the end of rated cooling to obtain the rated cooling temperature difference, and calculate the difference between the maximum temperature under the rated current flow duration and the ground ambient temperature to obtain the rated current flow temperature rise;

[0082] The rated temperature change ratio is obtained based on the ratio of the rated cooling temperature difference to the natural logarithm of the rated through-current temperature rise;

[0083] The rated time constant under rated current conditions is obtained based on the rated cooling recovery time and the rated temperature change rate.

[0084] Specifically, in this embodiment, the positive and negative pole operation modes of the deep well DC grounding electrode are set to an operation mode in which one of the deep well DC grounding electrodes is positive and the other is negative, that is, the W1 positive-W2 negative operation mode. In the positive and negative pole operation mode (W1 positive-W2 negative), the rated current flow temperature rise test is performed on the deep well DC grounding electrode. The current flow temperature rise test wiring in the positive and negative pole operation mode is as follows: Figure 7 As shown, the test power supply is connected to the busbar via a cable. Busbar B1 and busbar B2 are connected to the positive and negative poles of the test power supply, respectively. The through-current I loaded in the rated current flow temperature rise test is set to the rated current. In this embodiment, the through-current loaded in the rated current flow temperature rise test is twice the ratio of the DC transmission rated current to the number of deep well DC grounding electrodes. The specific calculation method is as follows:

[0085]

[0086] Where C is the rated DC transmission current of the DC transmission project, which is determined according to the specifications of the DC transmission project; N is the number of deep well DC grounding electrodes used in the project.

[0087] During the rated current flow temperature rise test, the temperature patrol meter records the temperature change at a sampling rate of 10Hz. Among all the thermocouples arranged, if the temperature of any thermocouple exceeds 90℃, the test is stopped immediately. In this embodiment, the start time of the rated current flow temperature rise test is recorded as time 0, and the duration of the rated current flow is recorded. , and mark the thermocouple number with the maximum temperature rise in the rated current flow temperature rise test and the thermocouple number with the minimum temperature rise After the rated current flow temperature rise test is completed, the thermocouples of the deep well DC grounding electrode are naturally cooled. During the natural cooling process, the temperature inspection instrument continues to record the temperature changes of the thermocouples at a sampling rate of 10 Hz until the temperatures of all thermocouples drop to within the range of ±2°C of the initial temperature. At this time, the cooling process is considered to be completed and this moment is recorded as the rated cooling end time. , where the temperature change formula during the natural cooling process is:

[0088]

[0089] Where, is the rated time constant; is the rated cooling end time; The duration of rated current flow; is the underground ambient temperature, where , is the initial temperature; is the temperature change of the deep well at a certain moment.

[0090] The mathematical expression of the rated time constant can be derived from the temperature change formula of the natural cooling process mentioned above. The mathematical expression of the rated time constant is:

[0091]

[0092] Where, is the rated cooling recovery time; is the rated cooling temperature difference; is the temperature rise at rated flow rate; is the rated temperature change ratio.

[0093] Looking back at the temperature change process in the temperature rise test, this embodiment can obtain the temperature change process expression in the temperature rise test:

[0094]

[0095] Where, is the rated current limit temperature increase of deep well.

[0096] The mathematical expression of the rated time constant and the temperature change process in the temperature rise test can be further used to obtain the mathematical expression of the rated current limit temperature rise amplitude of the deep well:

[0097]

[0098] Where, is the grounding resistance of the deep well; is the rated thermal resistance of the deep well.

[0099] The rated thermal resistance of the deep well can be solved by the mathematical expression of the rated current limit temperature rise of the deep well The mathematical expression is:

[0100]

[0101] At the same time, due to the rated time constant of the deep well Equal to its rated heat capacity Rated thermal resistance The product of , that is:

[0102]

[0103] From this we can calculate the rated thermal capacity of the deep well DC grounding electrode for:

[0104]

[0105] S4. Perform an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the duration of the overload current.

[0106] S5. After the overload current temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the overload temperature change data of the overload current natural cooling process, and the overload time constant under the overload current condition is calculated based on the overload temperature change data and the duration of the overload current.

[0107] In some embodiments, the step of calculating the overload time constant under the overload current condition based on the overload temperature change data and the overload current duration includes:

[0108] During the natural cooling process after the overload current temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is regarded as the end time of overload cooling;

[0109] The overload cooling recovery time is obtained based on the difference between the duration of overload flow and the end time of overload cooling.

[0110] Calculate the difference between the underground ambient temperature and the temperature at the end of overload cooling to obtain the overload cooling temperature difference, and calculate the difference between the maximum temperature during the duration of overload flow and the underground ambient temperature to obtain the overload flow temperature rise;

[0111] The overload temperature change ratio is obtained based on the ratio of the overload cooling temperature difference to the natural logarithm of the overload flow temperature rise;

[0112] According to the overload cooling recovery time and the overload temperature change ratio, the overload time constant under the overload current condition is obtained.

[0113] Specifically, this embodiment performs an overload current temperature rise test on the deep-well DC grounding electrode in the positive and negative polarity operation mode (W1 positive - W2 negative). In the overload current temperature rise test, the current applied during the overload current temperature rise test is twice the ratio of the product of the DC transmission rated current and the DC transmission overload current multiple to the number of deep-well DC grounding electrodes. The mathematical expression for the current applied during the overload current temperature rise test is:

[0114]

[0115] Where, is the through-current loaded for the overload through-current temperature rise test; k is the DC transmission overload current multiple of the DC transmission project, which is normally taken as 1.5; C is the DC transmission rated current of the DC transmission project, which is determined according to the specifications of the DC transmission project; N is the number of deep wells of deep well DC grounding electrodes used in the project.

[0116] In the overload current temperature rise test, the temperature patrol meter monitors the temperature change at a sampling frequency of 10Hz. If the temperature of any thermocouple exceeds 90℃ among all the thermocouples, the test will be terminated immediately. In this embodiment, the start time of the overload current temperature rise test is recorded as time 0, and the duration of the overload current is recorded. , and in the overload current temperature rise test, mark the thermocouple number with the maximum temperature rise and the thermocouple number with the minimum temperature rise After the overload current temperature rise test is completed, the thermocouples of the deep well DC grounding electrode are cooled naturally. During the natural cooling process, the temperature inspection instrument continues to record the temperature changes of the thermocouples at a sampling frequency of 10 Hz until the temperatures of all thermocouples drop to within the range of ±2°C of the initial temperature. At this time, the cooling process is considered to be completed and this moment is recorded as the overload cooling end time. , where the temperature change formula during the natural cooling process after the overload current temperature rise test is:

[0117]

[0118] Where, is the overload time constant; The duration of overload current flow; This is the time when overload cooling ends.

[0119] According to the temperature change formula of the natural cooling process after the overload current temperature rise test, the mathematical expression of the overload time constant can be derived. The mathematical expression of the overload time constant is:

[0120]

[0121] In addition, the formula for the retrospective overload temperature rise test in this embodiment is:

[0122]

[0123] Where, is the increase in the overload limit temperature of the deep well.

[0124] The mathematical expression of the overload time constant and the temperature change process expression in the retrospective overload temperature rise test can further be used to obtain the mathematical expression of the overload limit temperature rise amplitude of the deep well:

[0125]

[0126] Where, Overload thermal resistor for deep wells.

[0127] The overload thermal resistance of the deep well can be solved by the mathematical expression of the overload limit temperature rise of the deep well. The mathematical expression is:

[0128]

[0129] At the same time, due to the overload time constant of the deep well Equal to its overload heat capacity With overload thermal resistor The product of , that is:

[0130]

[0131] From this, the overload heat capacity can be derived The calculation formula is:

[0132]

[0133] S6. Evaluate the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant.

[0134] In some embodiments, the step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant includes:

[0135] The deep well overload coefficient is calculated based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple;

[0136] Calculate the ratio between the rated time constant and the preset rated time design value to obtain the rated time constant ratio;

[0137] Calculate the ratio between the overload time constant and the preset overload time design value to obtain the overload time constant ratio;

[0138] Based on the rated time constant and the rated current flow duration, the rated current limit temperature rise of the deep well DC grounding electrode is calculated;

[0139] Based on the overload time constant and the duration of overload current flow, the overload limit temperature increase of the deep well DC grounding electrode is calculated;

[0140] The rated-overload limit temperature rise ratio is calculated based on the rated current limit temperature rise and the overload limit temperature rise.

[0141] The deep well overload coefficient, rated time constant ratio, overload time constant ratio and rated-overload limit temperature rise ratio are defined as performance evaluation coefficients, and a preset thermal performance qualified threshold range for each performance evaluation coefficient is determined;

[0142] The performance evaluation coefficient is used to evaluate the thermal performance of the deep well DC grounding electrode during operation, and when all the performance evaluation coefficients meet the preset thermal performance qualified threshold range, the thermal performance of the deep well DC grounding electrode is determined to be qualified.

[0143] Specifically, when evaluating the thermal performance of the deep well DC grounding electrode, this embodiment combines the rated time constant, the overload time constant, and the related current and duration parameters to comprehensively and accurately evaluate its thermal performance. Specifically, this embodiment calculates the deep well overload coefficient based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple. According to the evaluation standard of the deep well overload coefficient, when the deep well overload coefficient is less than 1.0, this embodiment determines it as excellent; in the range of [1, 1.2) it is good; in the range of [1.2, 1.5] it is fair; and when it is greater than 1.5, it is determined to be poor. At the same time, this embodiment selects the rated time constant ratio and the overload time constant ratio as important evaluation indicators. The rated time constant ratio is defined as the rated time constant. The ratio of the rated time constant to the design value, where the design value is the rated time constant standard value set when designing the deep well DC grounding electrode. The overload time constant ratio is defined as the overload time constant The evaluation criteria for the rated time constant ratio and the overload time constant ratio, which are the ratios of the ratios to the preset overload time design value, are the same as those for the deep well overload coefficient. When the rated time constant ratio is less than 1.0, this embodiment is judged to be excellent; in the interval [1, 1.2), it is good; in the interval [1.2, 1.5], it is average; when it is greater than 1.5, it is judged to be poor; at the same time, when the overload time constant ratio is less than 1.0, this embodiment is judged to be excellent; in the interval [1, 1.2), it is good; in the interval [1.2, 1.5], it is average; and when it is greater than 1.5, it is judged to be poor.

[0144] In addition, the rated-overload limit temperature rise ratio is also an important indicator, which is expressed as the rated current limit temperature rise The increase in overload limit temperature The evaluation criteria for the rated-overload limit temperature rise ratio index are: when it is less than 2.25, it is judged as excellent; in the range of [2.25, 3) it is good; in the range of [3, 3.5] it is fair; and when it is greater than 3.5, it is judged as poor.

[0145] In summary, the deep-well overload coefficient, rated time constant ratio, overload time constant ratio, and rated-to-overload limit temperature rise ratio are defined as performance evaluation coefficients. A preset thermal performance qualification threshold range is determined for each performance evaluation coefficient based on the design requirements and operating experience of the deep-well DC grounding electrode. The resulting performance evaluation coefficient is then compared with the preset qualification threshold range to check whether all performance evaluation coefficients are within their qualification threshold ranges. If all meet these criteria, the deep-well DC grounding electrode is deemed to have qualified thermal performance. For example, if any one of the four parameters, the deep-well overload coefficient, rated time constant ratio, overload time constant ratio, and rated-to-overload limit temperature rise ratio, is rated "poor," or three or more are rated "fair," this embodiment determines that the deep-well DC grounding electrode's thermal performance has not met design expectations. Therefore, enhanced temperature monitoring is required during subsequent operation to ensure the safe operation of the deep-well DC grounding electrode. To further ensure the safety of the vertical DC grounding electrode, this embodiment also uses two deep-well W1 and W2 as its sub-grounding electrodes.

[0146] Based on the above embodiment, in some implementations, the step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant further includes:

[0147] The rated thermal resistance of the deep well DC grounding electrode is calculated based on the rated current limit temperature rise, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the rated current through-current temperature rise test;

[0148] The rated thermal capacity of the deep well DC grounding electrode is obtained according to the ratio of the rated thermal resistance and the rated time constant of the deep well DC grounding electrode;

[0149] The overload thermal resistance of the deep well DC grounding electrode is calculated based on the overload limit temperature rise, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the overload through-current temperature rise test;

[0150] Obtaining the overload thermal capacity of the deep well DC grounding electrode according to the ratio of the overload thermal resistance of the deep well DC grounding electrode to the overload time constant;

[0151] When judging the thermal performance of the deep well DC grounding electrode, the temperature response characteristics of the deep well DC grounding electrode under different operating conditions are determined according to the rated thermal resistance, rated thermal capacity, overload thermal resistance and overload thermal capacity;

[0152] According to the temperature response characteristics and the soil heat dissipation performance of the deep well DC grounding electrode, the continuous operation capability of the deep well DC grounding electrode was evaluated using a numerical simulation method.

[0153] The soil heat dissipation performance evaluation process of the deep well DC grounding electrode includes:

[0154] At the end of the rated current flow temperature rise test, obtain the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple from the preset thermocouple arrangement position;

[0155] At the end of the overload current temperature rise test, the overload current maximum temperature rise thermocouple and the overload current minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions;

[0156] Compare the maximum temperature rise thermocouple under rated current flow and the maximum temperature rise thermocouple under overload current flow to determine whether it is the maximum temperature rise point and obtain the maximum temperature rise detection result;

[0157] Compare the minimum temperature rise thermocouple when the rated current flows and the minimum temperature rise thermocouple when the overload current flows to determine whether it is the minimum temperature rise point and obtain the minimum temperature rise detection result;

[0158] The temperature rise distribution law is analyzed based on the maximum temperature rise detection results and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated.

[0159] In a specific embodiment, when evaluating the thermal performance of the deep well DC grounding electrode during operation, this embodiment introduces the concepts of thermal resistance and thermal capacitance, and combines it with the evaluation of the soil heat dissipation performance to more comprehensively understand its temperature response characteristics and continuous operation capabilities. Specifically, when determining that the thermal performance of the deep well DC grounding electrode is qualified, this embodiment combines the rated thermal resistance, rated thermal capacitance, overload thermal resistance and overload thermal capacitance, and analyzes the thermal stability of the grounding electrode under different current levels by comparing the thermal resistance and thermal capacitance under rated and overload conditions, thereby analyzing the temperature response characteristics of the deep well DC grounding electrode under different operating conditions. Then, at the end of the rated current flow temperature rise test, the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement position. At the same time, at the end of the overload flow temperature rise test, the overload flow maximum temperature rise thermocouple and the overload flow minimum temperature rise thermocouple are also obtained. This embodiment can judge which one by comparing the rated current flow maximum temperature rise thermocouple and the overload flow maximum temperature rise thermocouple. The maximum temperature rise point is determined, and the maximum temperature rise test result is recorded. The minimum temperature rise point is determined by comparing the thermocouple with the minimum temperature rise when the rated current is flowing and the thermocouple with the minimum temperature rise when the overload current is flowing. The minimum temperature rise test result is recorded. The temperature rise distribution pattern is analyzed based on the maximum and minimum temperature rise test results, and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated. For example, when the maximum temperature rise point occurs during the overload test, the minimum temperature rise point also rises slightly, indicating that the soil heat dissipation performance slightly decreases under overload conditions. For example, in terms of temperature rise locations, this embodiment records the maximum temperature rise locations, n1 and n2, and the minimum temperature rise locations, m1 and m2. As expected, the maximum temperature rise should occur at the end of the well. If the actual situation does not match this, it indicates an unexpected maximum temperature rise pattern. Similarly, if the minimum temperature rise location does not match the expectation, it is an unexpected maximum temperature rise pattern. This situation indicates that the soil thermal parameters in the well are unevenly distributed. However, the soil thermal parameters at the end of the deep well are relatively good. Although they do not meet the design expectations, they are still within an acceptable range.

[0160] By analyzing the temperature rise distribution pattern, this embodiment can further understand the thermal conductivity of the soil and the heat dissipation effect of the grounding electrode. Finally, based on the temperature response characteristics and the soil heat dissipation performance evaluation results, numerical simulation methods (such as finite element analysis and thermal network analysis) are used to evaluate the continuous operation capability of the deep-well DC grounding electrode. The numerical simulation should consider the impact of factors such as the grounding electrode's material and dimensions, the soil's thermophysical properties, the groundwater level, and climatic conditions on the heat dissipation performance. For example, in this embodiment, finite element analysis software can be used to establish a three-dimensional model of the deep-well DC grounding electrode, taking into account the thermal conductivity of the soil and the heat dissipation effect of the grounding electrode. Numerical simulation analysis is performed by inputting parameters such as current and time under rated and overload conditions. Based on the simulation results, the temperature distribution and heat dissipation effect of the grounding electrode under continuous operation are evaluated to ensure that it meets the design requirements. This allows for a comprehensive and accurate evaluation of the thermal performance of the deep-well DC grounding electrode during operation, providing a scientific basis for its design and optimization.

[0161] It should be noted that the size of the serial numbers of the above-mentioned processes does not 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 this application.

[0162] An embodiment of the present invention provides a method for monitoring the temperature distribution of a deep well grounding electrode. The method selects two deep well points arranged at intervals within the DC grounding electrode site according to the DC grounding electrode operation requirements, and constructs deep well DC grounding electrodes respectively; performs a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration; naturally cools the deep well DC grounding electrode to obtain rated temperature change data during the rated current flow natural cooling process, and obtains the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration; performs an overload flow temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the overload flow duration; naturally cools the deep well DC grounding electrode to obtain overload temperature change data during the overload flow natural cooling process, and obtains the overload time constant under the overload current condition based on the overload temperature change data and the overload flow duration; and evaluates the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant. Compared with the existing technology, this method can comprehensively and accurately evaluate the thermal performance of deep-well DC grounding electrodes during operation by arranging thermocouple temperature distribution monitoring in deep-well grounding electrodes and combining rated and overload current tests, thereby ensuring the safety and reliability of deep-well DC grounding electrodes under complex operating conditions.

[0163] In one embodiment, Figure 8 As shown, an embodiment of the present invention provides a deep well ground electrode temperature distribution monitoring device, the device comprising:

[0164] The grounding electrode layout module 101 is used to select two deep well locations arranged at intervals within the DC grounding electrode site according to the DC grounding electrode operation requirements, and to construct deep well DC grounding electrodes at each of the deep well locations;

[0165] The rated temperature rise test module 102 is used to perform a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration;

[0166] The rated temperature rise analysis module 103 is used to naturally cool the deep-well DC grounding electrode after the rated current flow temperature rise test is completed, obtain the rated temperature change data during the natural cooling process of the rated current flow, and calculate the rated time constant under the rated current condition based on the rated temperature change data and the rated current flow duration;

[0167] The overload temperature rise test module 104 is used to perform an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation modes to obtain the duration of the overload current;

[0168] The overload temperature rise analysis module 105 is used to naturally cool the deep well DC grounding electrode after the overload current temperature rise test is completed, obtain the overload temperature change data during the natural cooling process of the overload current, and calculate the overload time constant under the overload current condition based on the overload temperature change data and the duration of the overload current;

[0169] The grounding electrode evaluation module 106 is configured to evaluate the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant.

[0170] In this embodiment, each deep-well DC grounding electrode is composed of three hollow steel pipes of the same length buried at different distances underground. The deep-well DC grounding electrode and each hollow steel pipe are connected by coke filling; thermocouples are evenly distributed around the bottom of the deep-well DC grounding electrode, and a pair of thermocouples are distributed at different distances from the bottom of the deep-well DC grounding electrode. Thermocouples are arranged at intervals in the three hollow steel pipes inside the deep-well DC grounding electrode, and all thermocouples are connected to the temperature patrol meter in sequence so that the temperature patrol meter can monitor the temperature changes of the thermocouples in real time.

[0171] In this embodiment, the positive and negative pole operation mode is an operation mode in which one deep well DC grounding pole is a positive pole and the other deep well DC grounding pole is a negative pole.

[0172] In this embodiment, the through-current loaded in the rated current through-current temperature rise test is twice the ratio of the DC transmission rated current to the number of deep well DC grounding electrodes.

[0173] In this embodiment, the rated time constant under the rated current condition is calculated based on the rated temperature change data and the rated current flow duration, specifically including:

[0174] During the natural cooling process after the rated current flow temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is taken as the rated cooling end time;

[0175] Obtaining a rated cooling recovery time according to a difference between the rated current flow duration and the rated cooling end time;

[0176] Calculating the difference between the underground ambient temperature and the temperature at the end of the rated cooling to obtain the rated cooling temperature difference, and calculating the difference between the maximum temperature during the rated current flow duration and the underground ambient temperature to obtain the rated current flow temperature rise;

[0177] Obtaining a rated temperature change ratio according to a ratio of the rated cooling temperature difference to the natural logarithm of the rated through-flow temperature rise;

[0178] A rated time constant under rated current conditions is obtained according to the rated cooling recovery time and the rated temperature change rate.

[0179] In this embodiment, the through-current loaded in the overload through-current temperature rise test is twice the ratio of the product of the DC transmission rated current and the DC transmission overload current multiple to the number of deep well DC grounding electrodes.

[0180] In this embodiment, the overload time constant under the overload current condition is calculated based on the overload temperature change data and the overload current duration, specifically including:

[0181] During the natural cooling process after the overload current temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is regarded as the end time of overload cooling;

[0182] Obtaining an overload cooling recovery time based on a difference between the duration of the overload current flow and the end time of the overload cooling;

[0183] Calculating the difference between the underground ambient temperature and the temperature at the end of the overload cooling to obtain the overload cooling temperature difference, and calculating the difference between the maximum temperature during the overload flow duration and the underground ambient temperature to obtain the overload flow temperature rise;

[0184] Obtaining an overload temperature change ratio according to a ratio of the overload cooling temperature difference to the natural logarithm of the overload flow temperature rise amplitude;

[0185] An overload time constant under an overload current condition is obtained according to the overload cooling recovery time and the overload temperature change ratio.

[0186] In this embodiment, evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant specifically includes:

[0187] Calculating a deep well overload coefficient based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple;

[0188] Calculating a ratio between the rated time constant and a preset rated time design value to obtain a rated time constant ratio;

[0189] Calculating a ratio between the overload time constant and a preset overload time design value to obtain an overload time constant ratio;

[0190] Calculating the rated current limit temperature rise of the deep well DC grounding electrode according to the rated time constant and the rated current flow duration;

[0191] Calculating the overload limit temperature increase of the deep well DC grounding electrode according to the overload time constant and the duration of the overload current flow;

[0192] Calculating a rated-to-overload limit temperature increase ratio according to the rated current limit temperature increase amplitude and the overload limit temperature increase amplitude;

[0193] defining the deep well overload coefficient, the rated time constant ratio, the overload time constant ratio, and the rated-overload limit temperature rise ratio as performance evaluation coefficients, and determining a preset thermal performance qualified threshold interval for each performance evaluation coefficient;

[0194] The performance evaluation coefficient is used to evaluate the thermal performance of the deep well DC grounding electrode during operation, and when all the performance evaluation coefficients meet the preset thermal performance qualified threshold range, the thermal performance of the deep well DC grounding electrode is determined to be qualified.

[0195] In this embodiment, the evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant specifically further includes:

[0196] The rated thermal resistance of the deep well DC grounding electrode is calculated based on the rated current limit temperature rise, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the rated current through-current temperature rise test;

[0197] The rated thermal capacity of the deep well DC grounding electrode is obtained according to the ratio of the rated thermal resistance of the deep well DC grounding electrode and the rated time constant;

[0198] The overload thermal resistance of the deep well DC grounding electrode is calculated based on the overload limit temperature rise amplitude, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded in the overload through-current temperature rise test;

[0199] Obtaining the overload thermal capacity of the deep well DC grounding electrode according to the ratio of the overload thermal resistance of the deep well DC grounding electrode to the overload time constant;

[0200] When judging that the thermal performance of the deep well DC grounding electrode is qualified, the temperature response characteristics of the deep well DC grounding electrode under different operating conditions are determined according to the rated thermal resistance, rated thermal capacity, overload thermal resistance and overload thermal capacity;

[0201] According to the temperature response characteristics and the soil heat dissipation performance of the deep well DC grounding electrode, the continuous operation capability of the deep well DC grounding electrode is evaluated using a numerical simulation method.

[0202] In this embodiment, the soil heat dissipation performance evaluation process of the deep well DC grounding electrode includes:

[0203] At the end of the rated current flow temperature rise test, obtain the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple from the preset thermocouple arrangement position;

[0204] At the end of the overload current temperature rise test, the overload current maximum temperature rise thermocouple and the overload current minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions;

[0205] Comparing the maximum temperature rise thermocouple at the rated current flow and the maximum temperature rise thermocouple at the overload current flow to determine whether it is the maximum temperature rise point, and obtaining a maximum temperature rise detection result;

[0206] Comparing the rated current minimum temperature rise thermocouple with the overload minimum temperature rise thermocouple to determine whether it is the minimum temperature rise point, and obtaining a minimum temperature rise detection result;

[0207] The temperature rise distribution law is analyzed based on the maximum temperature rise detection results and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated.

[0208] The specific definition of a deep well grounding electrode temperature distribution monitoring device can be found in the above-mentioned definition of a deep well grounding electrode temperature distribution monitoring method, which will not be repeated here.

[0209] An embodiment of the present invention provides a deep well grounding electrode temperature distribution monitoring device, wherein the grounding electrode layout module of the device selects two deep well points arranged at intervals within the DC grounding electrode site according to the DC grounding electrode operation requirements, and constructs deep well DC grounding electrodes respectively; the rated temperature rise test module performs a rated current flow temperature rise test on the deep well DC grounding electrode under a preset positive and negative pole operation mode to obtain the rated current flow duration; the rated temperature rise analysis module naturally cools the deep well DC grounding electrode to obtain rated temperature change data during the rated current flow natural cooling process, and analyzes the rated temperature change data based on the rated temperature change data. The rated time constant under rated current conditions is obtained by combining the rated current flow duration and the rated current flow duration. The overload temperature rise test module performs an overload current flow temperature rise test on the deep-well DC grounding electrode in the positive and negative polarity operating modes to obtain the overload current flow duration. The overload temperature rise analysis module naturally cools the deep-well DC grounding electrode to obtain overload temperature change data during the overload current flow natural cooling process, and then obtains the overload time constant under overload current conditions based on the overload temperature change data and the overload current flow duration. The grounding electrode evaluation module evaluates the thermal performance of the deep-well DC grounding electrode during operation based on the rated time constant and the overload time constant. Compared with existing technologies, this device, by arranging thermocouple temperature distribution monitoring in the deep-well grounding electrode and combining rated and overload current flow tests, can comprehensively and accurately evaluate the thermal performance of the deep-well DC grounding electrode during operation, ensuring the safety and reliability of the deep-well DC grounding electrode under complex operating conditions.

[0210] In one embodiment, the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above method are implemented.

[0211] The above-described embodiments merely represent several preferred implementations of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art could make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the scope of protection of the claims.

Claims

1. A method for monitoring temperature distribution of a deep well grounding electrode, characterized in that: The following steps are involved: According to the operation requirements of the DC grounding electrode, two deep well locations arranged at intervals are selected within the DC grounding electrode site, and deep well DC grounding electrodes are respectively constructed at the deep well locations; Performing a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration; After the rated current flow temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the rated temperature change data of the rated current flow natural cooling process, and the rated time constant under the rated current condition is calculated based on the rated temperature change data and the rated current flow duration, which is specifically: During the natural cooling process after the rated current flow temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is taken as the rated cooling end time; Obtaining a rated cooling recovery time according to a difference between the rated current flow duration and the rated cooling end time; Calculate the difference between the underground ambient temperature and the temperature at the end of the rated cooling to obtain the rated cooling temperature difference, and calculate the difference between the maximum temperature during the rated current flow duration and the underground ambient temperature to obtain the rated current flow temperature rise; The rated temperature change ratio is obtained according to the ratio of the rated cooling temperature difference to the natural logarithm of the rated through-current temperature rise amplitude; According to the rated cooling recovery time and the rated temperature change ratio, a rated time constant under rated current conditions is obtained; Performing an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the duration of the overload current; After the overload current temperature rise test is completed, the deep well DC grounding electrode is naturally cooled to obtain the overload temperature change data of the overload current natural cooling process, and the overload time constant under the overload current condition is calculated based on the overload temperature change data and the overload current duration; The thermal performance of the deep well DC grounding electrode during operation is evaluated based on the rated time constant and the overload time constant.

2. A method for monitoring temperature distribution of a deep well grounding electrode according to claim 1, characterized in that: Each of the deep well DC grounding electrodes is composed of three hollow steel pipes of the same length buried at different distances underground, and the deep well DC grounding electrode is connected to each hollow steel pipe by coke filling; Thermocouples are evenly distributed around the bottom of the deep well DC grounding electrode, and a pair of thermocouples are evenly distributed at different distances from the bottom of the deep well DC grounding electrode. Thermocouples are arranged at intervals in the three sections of hollow steel pipes inside the deep well DC grounding electrode. All thermocouples are connected to a temperature patrol meter in sequence so that the temperature patrol meter can monitor the temperature changes of the thermocouples in real time.

3. A method for monitoring temperature distribution of a deep well grounding electrode according to claim 1, characterized in that: The positive and negative pole operation mode is an operation mode in which one deep well DC grounding pole is the positive pole and the other deep well DC grounding pole is the negative pole.

4. A method for monitoring temperature distribution of a deep well grounding electrode according to claim 1, characterized in that: The through-current loaded in the rated current through-current temperature rise test is twice the ratio of the rated current of the DC transmission to the number of deep well DC grounding electrodes.

5. A method for monitoring temperature distribution of a deep well grounding electrode according to claim 1, characterized in that: The through-current loaded in the overload through-current temperature rise test is twice the ratio of the product of the DC transmission rated current and the DC transmission overload current multiple to the number of deep well DC grounding electrodes.

6. A method for monitoring temperature distribution of a deep well grounding electrode as claimed in claim 1, characterized in that: The step of calculating the overload time constant under the overload current condition according to the overload temperature change data and the overload current duration comprises: During the natural cooling process after the overload current temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is regarded as the end time of overload cooling; Obtaining the overload cooling recovery time according to the difference between the overload current duration and the overload cooling end time; Calculate the difference between the underground ambient temperature and the temperature at the end of the overload cooling to obtain the overload cooling temperature difference, and calculate the difference between the maximum temperature under the overload flow duration and the underground ambient temperature to obtain the overload flow temperature rise amplitude; Obtaining an overload temperature change ratio according to a ratio of the overload cooling temperature difference to the natural logarithm of the overload flow temperature rise amplitude; An overload time constant under an overload current condition is obtained according to the overload cooling recovery time and the overload temperature change ratio.

7. A method for monitoring temperature distribution of a deep well grounding electrode as claimed in claim 1, characterized in that: The step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant comprises: The deep well overload coefficient is calculated based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple; Calculating a ratio between the rated time constant and a preset rated time design value to obtain a rated time constant ratio; Calculating the ratio between the overload time constant and a preset overload time design value to obtain an overload time constant ratio; According to the rated time constant and the rated current flow duration, the rated current limit temperature rise amplitude of the deep well DC grounding electrode is calculated; According to the overload time constant and the duration of the overload current flow, the overload limit temperature increase amplitude of the deep well DC grounding electrode is calculated; Calculating a rated-to-overload limit temperature increase ratio according to the rated current limit temperature increase amplitude and the overload limit temperature increase amplitude; The deep well overload coefficient, the rated time constant ratio, the overload time constant ratio and the rated-overload limit temperature rise ratio are defined as performance evaluation coefficients, and a preset thermal performance qualified threshold interval of each performance evaluation coefficient is determined; The performance evaluation coefficient is used to evaluate the thermal performance of the deep well DC grounding electrode during operation, and when all the performance evaluation coefficients meet the preset thermal performance qualified threshold range, the thermal performance of the deep well DC grounding electrode is determined to be qualified.

8. A method for monitoring temperature distribution of a deep well grounding electrode as claimed in claim 7, characterized in that: The step of evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant also includes: The rated thermal resistance of the deep well DC grounding electrode is calculated based on the rated current limit temperature rise amplitude, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded by the rated current through-current temperature rise test; According to the ratio of the rated thermal resistance of the deep well DC grounding electrode and the rated time constant, the rated thermal capacity of the deep well DC grounding electrode is obtained; The overload thermal resistance of the deep well DC grounding electrode is calculated according to the overload limit temperature increase amplitude, the grounding resistance of the deep well DC grounding electrode and the through-current loaded by the overload through-current temperature rise test; According to the ratio of the overload thermal resistance of the deep well DC grounding electrode and the overload time constant, the overload thermal capacity of the deep well DC grounding electrode is obtained; When judging that the thermal performance of the deep well DC grounding electrode is qualified, the temperature response characteristics of the deep well DC grounding electrode under different operating conditions are determined according to the rated thermal resistance, rated thermal capacity, overload thermal resistance and overload thermal capacity; According to the temperature response characteristics and the soil heat dissipation performance of the deep well DC grounding electrode, a numerical simulation method is used to evaluate the continuous operation capability of the deep well DC grounding electrode.

9. A method for monitoring temperature distribution of a deep well grounding electrode as claimed in claim 8, characterized in that: The soil heat dissipation performance evaluation process of the deep well DC grounding electrode includes: At the end of the rated current flow temperature rise test, the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions; At the end of the overload current temperature rise test, the overload current maximum temperature rise thermocouple and the overload current minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions; Compare the rated current maximum temperature rise thermocouple with the overload current maximum temperature rise thermocouple to determine whether it is the maximum temperature rise point, and obtain the maximum temperature rise detection result; Compare the rated current minimum temperature rise thermocouple with the overload current minimum temperature rise thermocouple to determine whether it is the minimum temperature rise point, and obtain the minimum temperature rise detection result; The temperature rise distribution law is analyzed according to the maximum temperature rise detection results and the minimum temperature rise detection results, and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated.

10. A deep well grounding electrode temperature distribution monitoring device, characterized in that: The device comprises: A grounding electrode layout module is used to select two deep well locations arranged at intervals within the DC grounding electrode site according to the DC grounding electrode operation requirements, and to construct deep well DC grounding electrodes at the deep well locations respectively; A rated temperature rise test module is used to perform a rated current flow temperature rise test on the deep well DC grounding electrode in a preset positive and negative pole operation mode to obtain the rated current flow duration; The rated temperature rise analysis module is used to naturally cool the deep well DC grounding electrode after the rated current flow temperature rise test is completed, obtain the rated temperature change data of the rated current flow natural cooling process, and calculate the rated time constant under the rated current condition according to the rated temperature change data and the rated current flow duration, specifically: During the natural cooling process after the rated current flow temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is taken as the rated cooling end time; Obtaining a rated cooling recovery time according to a difference between the rated current flow duration and the rated cooling end time; Calculate the difference between the underground ambient temperature and the temperature at the end of the rated cooling to obtain the rated cooling temperature difference, and calculate the difference between the maximum temperature during the rated current flow duration and the underground ambient temperature to obtain the rated current flow temperature rise; The rated temperature change ratio is obtained according to the ratio of the rated cooling temperature difference to the natural logarithm of the rated through-current temperature rise amplitude; According to the rated cooling recovery time and the rated temperature change ratio, a rated time constant under rated current conditions is obtained; An overload temperature rise test module is used to perform an overload current temperature rise test on the deep well DC grounding electrode in the positive and negative pole operation mode to obtain the duration of the overload current; The overload temperature rise analysis module is used to naturally cool the deep well DC grounding electrode after the overload current temperature rise test is completed, obtain the overload temperature change data of the overload current natural cooling process, and calculate the overload time constant under the overload current condition according to the overload temperature change data and the overload current duration; The grounding electrode evaluation module is used to evaluate the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant.

11. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: Each of the deep well DC grounding electrodes is composed of three hollow steel pipes of the same length buried at different distances underground, and the deep well DC grounding electrode is connected to each hollow steel pipe by coke filling; Thermocouples are evenly distributed around the bottom of the deep well DC grounding electrode, and a pair of thermocouples are evenly distributed at different distances from the bottom of the deep well DC grounding electrode. Thermocouples are arranged at intervals in the three sections of hollow steel pipes inside the deep well DC grounding electrode. All thermocouples are connected to a temperature patrol meter in sequence so that the temperature patrol meter can monitor the temperature changes of the thermocouples in real time.

12. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: The positive and negative pole operation mode is an operation mode in which one deep well DC grounding pole is the positive pole and the other deep well DC grounding pole is the negative pole.

13. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: The through-current loaded in the rated current through-current temperature rise test is twice the ratio of the rated current of the DC transmission to the number of deep well DC grounding electrodes.

14. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: The through-current loaded in the overload through-current temperature rise test is twice the ratio of the product of the DC transmission rated current and the DC transmission overload current multiple to the number of deep well DC grounding electrodes.

15. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: The calculating of the overload time constant under the overload current condition according to the overload temperature change data and the overload current duration specifically includes: During the natural cooling process after the overload current temperature rise test, the time when the thermocouple temperature of the deep well DC grounding electrode drops to the initial temperature range is regarded as the end time of overload cooling; Obtaining the overload cooling recovery time according to the difference between the overload current duration and the overload cooling end time; Calculate the difference between the underground ambient temperature and the temperature at the end of the overload cooling to obtain the overload cooling temperature difference, and calculate the difference between the maximum temperature under the overload flow duration and the underground ambient temperature to obtain the overload flow temperature rise amplitude; Obtaining an overload temperature change ratio according to a ratio of the overload cooling temperature difference to the natural logarithm of the overload flow temperature rise amplitude; An overload time constant under an overload current condition is obtained according to the overload cooling recovery time and the overload temperature change ratio.

16. A deep well ground electrode temperature distribution monitoring device as claimed in claim 10, characterized in that: The evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant specifically includes: The deep well overload coefficient is calculated based on the product of the ratio of the rated time constant to the overload time constant and the DC transmission overload current multiple; Calculating a ratio between the rated time constant and a preset rated time design value to obtain a rated time constant ratio; Calculating the ratio between the overload time constant and a preset overload time design value to obtain an overload time constant ratio; According to the rated time constant and the rated current flow duration, the rated current limit temperature rise amplitude of the deep well DC grounding electrode is calculated; According to the overload time constant and the duration of the overload current flow, the overload limit temperature increase amplitude of the deep well DC grounding electrode is calculated; Calculating a rated-to-overload limit temperature increase ratio according to the rated current limit temperature increase amplitude and the overload limit temperature increase amplitude; The deep well overload coefficient, the rated time constant ratio, the overload time constant ratio and the rated-overload limit temperature rise ratio are defined as performance evaluation coefficients, and a preset thermal performance qualified threshold interval of each performance evaluation coefficient is determined; The performance evaluation coefficient is used to evaluate the thermal performance of the deep well DC grounding electrode during operation, and when all the performance evaluation coefficients meet the preset thermal performance qualified threshold range, the thermal performance of the deep well DC grounding electrode is determined to be qualified.

17. A deep well ground electrode temperature distribution monitoring device as claimed in claim 16, characterized in that: The evaluating the thermal performance of the deep well DC grounding electrode during operation based on the rated time constant and the overload time constant specifically includes: The rated thermal resistance of the deep well DC grounding electrode is calculated based on the rated current limit temperature rise amplitude, the grounding resistance of the deep well DC grounding electrode, and the through-current loaded by the rated current through-current temperature rise test; According to the ratio of the rated thermal resistance of the deep well DC grounding electrode and the rated time constant, the rated thermal capacity of the deep well DC grounding electrode is obtained; The overload thermal resistance of the deep well DC grounding electrode is calculated according to the overload limit temperature increase amplitude, the grounding resistance of the deep well DC grounding electrode and the through-current loaded by the overload through-current temperature rise test; According to the ratio of the overload thermal resistance of the deep well DC grounding electrode and the overload time constant, the overload thermal capacity of the deep well DC grounding electrode is obtained; When judging that the thermal performance of the deep well DC grounding electrode is qualified, the temperature response characteristics of the deep well DC grounding electrode under different operating conditions are determined according to the rated thermal resistance, rated thermal capacity, overload thermal resistance and overload thermal capacity; According to the temperature response characteristics and the soil heat dissipation performance of the deep well DC grounding electrode, a numerical simulation method is used to evaluate the continuous operation capability of the deep well DC grounding electrode.

18. A deep well ground electrode temperature distribution monitoring device as claimed in claim 17, characterized in that: The soil heat dissipation performance evaluation process of the deep well DC grounding electrode includes: At the end of the rated current flow temperature rise test, the rated current flow maximum temperature rise thermocouple and the rated current flow minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions; At the end of the overload current temperature rise test, the overload current maximum temperature rise thermocouple and the overload current minimum temperature rise thermocouple are obtained from the preset thermocouple arrangement positions; Compare the rated current maximum temperature rise thermocouple with the overload current maximum temperature rise thermocouple to determine whether it is the maximum temperature rise point, and obtain the maximum temperature rise detection result; Compare the rated current minimum temperature rise thermocouple with the overload current minimum temperature rise thermocouple to determine whether it is the minimum temperature rise point, and obtain the minimum temperature rise detection result; The temperature rise distribution law is analyzed according to the maximum temperature rise detection results and the minimum temperature rise detection results, and the soil heat dissipation performance of the deep well DC grounding electrode is evaluated.

19. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 9 is implemented.

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