A power distribution box multi-sensing temperature rise early warning method and system
By acquiring the sensor's detected temperature and fixed pressure, analyzing the sensor's fixed loss pressure, identifying and correcting the type of additional thermal resistance degradation, the problem of inaccurate temperature measurement caused by poor contact of wireless temperature sensors in power distribution boxes is solved, and more accurate temperature rise early warning is achieved.
Patent Information
- Application Number
- CN202611228577.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-13
- Publication Date
- 2026-11-06
AI Technical Summary
Existing wireless temperature sensors in power distribution boxes suffer from uneven contact surfaces, oxidation, or insufficient installation pressure, resulting in air gaps or thermal resistance between the sensing surface and the measured point. This causes the measured temperature to be lower than the actual core temperature, thus affecting the accuracy of temperature rise warnings.
By acquiring the sensor's detected temperature and fixed detection pressure, it is determined whether the sensor's fixed loss pressure meets the preset pressure deviation alarm threshold. If not, the sensor's fixed loss pressure is analyzed to determine the type of additional thermal resistance degradation at the measured point, and the sensor's detected temperature is corrected according to this type to generate the actual temperature at the measured point, ultimately determining the distribution box temperature rise early warning report.
The accuracy of temperature rise warning for distribution boxes has been improved. By identifying and correcting the type of additional thermal resistance degradation, the accuracy of temperature detection by the sensor is ensured, resulting in more precise temperature rise warning.
Smart Images
Figure CN123045562A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of temperature monitoring of distribution boxes, and in particular to a multi-sensor temperature rise early warning method and system for distribution boxes. Background Technology
[0002] Distribution box temperature rise early warning refers to the process of installing temperature sensors at key points in the distribution box to detect the temperature at these key points and then using various algorithms to determine whether the temperature of the distribution box is normal.
[0003] In related technologies, wireless temperature sensors are typically used to monitor the temperature of distribution boxes. The wireless temperature sensors are fixed to the contacts or busbars of the distribution box using cable ties, bolts, or magnetic attraction. After the wireless temperature sensors detect the temperature at key points, the temperature rise of the distribution box is determined to be abnormal by calculating and comparing parameters such as absolute threshold, relative temperature rise, and temperature rise rate.
[0004] Regarding the aforementioned technologies, when wireless temperature sensors are fixed to key locations in a distribution box using cable ties, bolts, or magnetic attraction, uneven contact surfaces, oxidation, or insufficient installation pressure can cause air gaps or thermal resistance between the sensing surface of the wireless temperature sensor and the measured point. This results in temperature measurements being lower than the actual core temperature, leading to inaccurate temperature rise warnings for the distribution box. There is still room for improvement in these technologies. Summary of the Invention
[0005] To improve the accuracy of temperature rise warning for distribution boxes, this application provides a multi-sensor temperature rise warning method and system for distribution boxes.
[0006] Firstly, this application provides a multi-sensor temperature rise early warning method for distribution boxes, employing the following technical solution: A multi-sensor temperature rise early warning method for distribution boxes includes: Obtain the sensor-detected temperature and sensor-fixed detection pressure at the measured point in the distribution box; The sensor fixing loss pressure is determined based on the preset initial fixing pressure and the sensor fixing detection pressure. Determine whether the fixed loss pressure of the sensor meets the preset pressure deviation alarm threshold. If the conditions are met, the temperature detected by the sensor is defined as the actual temperature of the measured point. If not, the fixed loss pressure of the sensor is analyzed to determine the type of additional thermal resistance degradation at the measured point. The sensor's detected temperature is corrected based on the type of additional thermal resistance degradation to generate the actual temperature at the measured point. The distribution box temperature rise early warning report is generated and a prompt is output based on the actual temperature of the measured point.
[0007] Optionally, the steps of analyzing the sensor's fixed loss pressure to determine the type of additional thermal resistance degradation at the measured point include: The pressure deviation ratio at the measured point is determined based on the sensor's fixed loss pressure and initial fixed pressure. The rate of change of the loss pressure at the measured point is determined based on the fixed loss pressure of the sensor. Obtain the percentage change in thermal response time and the trend of temperature change at the measured point; The type of additional thermal resistance degradation is determined based on the pressure deviation ratio, the rate of change of loss pressure, the rate of change of thermal response time, and the temperature change trend.
[0008] Optionally, the steps for obtaining the percentage change in thermal response time at the measured point include: Thermal excitation is applied to the measured points in the distribution box based on the preset variable load current, and the temperature-time change curve is obtained. Determine the current thermal response time constant based on the temperature-time change curve; The thermal response time change ratio of the measured point is determined based on the current thermal response time constant and the preset initial thermal response time constant.
[0009] Optionally, the steps for obtaining the temperature change trend at the measured point include: Thermal excitation is applied to the measured points in the distribution box, and steady-state current and steady-state detection temperature are obtained; The true temperature estimate of the measured point is determined based on the steady-state current value and the preset comprehensive thermal coefficient. The actual temperature deviation at the measured point is determined based on the steady-state detection temperature and the estimated actual temperature. Plot the current change-temperature deviation curve based on the steady-state current value and the actual temperature deviation. The temperature change trend at the measured point is determined based on the current change-temperature deviation curve.
[0010] Optionally, the step of correcting the sensor's detected temperature based on the type of additional thermal resistance degradation to generate the actual temperature at the measured point includes: The current additional thermal resistance at the test point is determined based on the type of additional thermal resistance degradation. Obtain the total thermal resistance of the sensor and the ambient temperature of the power distribution box; The temperature correction factor is determined based on the current additional thermal resistance and the total heat dissipation thermal resistance of the sensor. The temperature correction range is determined based on the temperature detected by the sensor and the ambient temperature of the distribution box. Calculate the product of the temperature correction factor and the temperature correction range to generate the actual corrected temperature; Calculate the sum of the sensor-detected temperature and the actual corrected temperature to generate the actual temperature of the measured point.
[0011] Optionally, the steps for determining the current additional thermal resistance at the test point based on the type of additional thermal resistance degradation include: Determine whether the additional thermal resistance degradation type is the preset gap type or the preset oxidation type. If it is a gap-type degradation type, the current additional thermal resistance of the measured point is determined based on the sensor's fixed loss pressure. If the degradation type is oxidation, then obtain the current steady-state current value; The current steady-state current value, the total thermal resistance of the sensor, and the ambient temperature of the distribution box are analyzed to generate the current additional thermal resistance of the measured point.
[0012] Optionally, the step of determining the current additional thermal resistance at the measured point based on the sensor's fixed loss pressure includes: The current gap thickness at the measured point is determined based on the sensor's fixed loss pressure and the preset fixed equivalent stiffness. The current additional thermal resistance of the measured point is determined based on the current gap thickness, the preset air thermal conductivity, and the preset effective heat transfer area.
[0013] Optionally, the steps of analyzing the current steady-state current value, the total thermal resistance of the sensor, and the ambient temperature of the distribution box to generate the current additional thermal resistance of the measured point include: The surface temperature estimate of the measured point is determined based on the current steady-state current value and the preset comprehensive thermal coefficient. The surface temperature estimate, sensor detection temperature, and distribution box ambient temperature are analyzed to determine the thermal resistance correction coefficient. Calculate the product of the thermal resistance correction factor and the total thermal resistance of the sensor to generate the current additional thermal resistance of the measured point.
[0014] Secondly, this application provides a multi-sensor temperature rise early warning system for distribution boxes, which adopts the following technical solution: A multi-sensor temperature rise early warning system for distribution boxes includes: The acquisition module is used to acquire the sensor-detected temperature and the sensor-fixed detection pressure; A memory for storing a program for a multi-sensor temperature rise early warning method for a distribution box as described in any of the preceding claims; The processor and the program in the memory can be loaded and executed by the processor to implement a multi-sensor temperature rise early warning method for a distribution box as described in any of the above.
[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. By determining the fixed loss pressure of the sensor and comparing it with the pressure deviation alarm threshold, it is possible to determine whether there is an air gap or oxide layer between the temperature sensing surface of the temperature sensor and the measured point, causing additional thermal resistance and resulting in inaccurate temperature measurement. Based on the type of additional thermal resistance degradation, the sensor's detected temperature is corrected to obtain the actual temperature of the measured point. Based on the actual temperature of the measured point, a temperature rise warning report for the distribution box is determined, thereby improving the accuracy of the temperature rise warning for the distribution box. 2. The type of additional thermal resistance degradation is determined by the pressure deviation ratio, the rate of change of loss pressure, the rate of change of thermal response time, and the temperature change trend. The type of additional thermal resistance is identified from the dimensions of the formation process of air gap and oxide layer and the rate of temperature transfer, thereby improving the accuracy of the type of additional thermal resistance degradation. 3. Determine the temperature correction coefficient by using the current additional thermal resistance and the total heat dissipation thermal resistance of the sensor. Multiply the temperature correction coefficient by the temperature correction range to determine the actual corrected temperature that the sensor does not detect due to the influence of thermal resistance. Then, calculate the sum of the sensor detection temperature and the actual corrected temperature to obtain the actual temperature of the measured point, thereby improving the accuracy of the time temperature of the measured point. Attached Figure Description
[0016] Figure 1 This is a flowchart of a multi-sensor temperature rise early warning method for a distribution box according to an embodiment of this application.
[0017] Figure 2 This is a flowchart of the steps in this application embodiment to analyze the fixed loss pressure of the sensor to determine the type of additional thermal resistance degradation at the measured point.
[0018] Figure 3 This is a flowchart of the steps for obtaining the thermal response time change ratio of the measured point in the embodiments of this application.
[0019] Figure 4 This is a flowchart of the steps for obtaining the temperature change trend of the measured point in the embodiments of this application.
[0020] Figure 5 This is a flowchart of the steps in this application embodiment to correct the sensor detection temperature according to the type of additional thermal resistance degradation in order to generate the actual temperature of the measured point.
[0021] Figure 6 This is a flowchart of the steps for determining the current additional thermal resistance of the test point based on the type of additional thermal resistance degradation in an embodiment of this application.
[0022] Figure 7 This is a flowchart of the steps for determining the current additional thermal resistance of the measured point based on the fixed loss pressure of the sensor in the embodiments of this application.
[0023] Figure 8This is a flowchart of the steps in this application embodiment to analyze the current steady-state current value, the total heat dissipation thermal resistance of the sensor, and the ambient temperature of the distribution box to generate the current additional thermal resistance of the measured point. Detailed Implementation
[0024] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figures 1 to 8 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.
[0025] Reference Figure 1 This application discloses a multi-sensor temperature rise early warning method for distribution boxes, including the following steps: Step S100: Obtain the sensor-detected temperature and sensor-fixed detection pressure at the measured point in the distribution box.
[0026] In this embodiment, the temperature detected by the sensor is the temperature value output by the temperature sensor after detecting the measured point in the distribution box, such as contacts or busbars. The temperature sensor is fixed to the measured point by the operator using cable ties or bolts, ensuring that the sensor's sensing surface is in contact with the measured point. When there is no additional thermal resistance between the temperature sensor and the measured point, the sensor-detected temperature is the actual temperature of the measured point. Therefore, the temperature detected by the sensor can be used to analyze the temperature rise of the distribution box. However, when there is additional thermal resistance between the temperature sensor and the measured point, the sensor-detected temperature serves as a reference temperature, and corrections are made based on the additional thermal resistance to determine the actual temperature of the measured point. After this, an early warning system is issued for the temperature rise of the distribution box. In this embodiment, the temperature sensor can be a wireless or wired sensor. The operator sets a specific sampling period to detect the temperature of the measured point.
[0027] The sensor fixing detection pressure is the feedback force of the pressure between the temperature sensing surface of the temperature sensor and the measured point, which is detected by a pressure sensor. When the temperature sensor is fixed to the measured point with cable ties or bolts, the pressure sensor is fixed on the side away from the measured point, thus transmitting the clamping force of the cable ties or bolts to the pressure sensor. When the gap between the temperature sensor and the measured point increases or the measured point oxidizes, the clamping force decreases and is fed back to the pressure sensor, resulting in the sensor fixing detection pressure. In this embodiment, a thin-film pressure sensor is used.
[0028] Step S101: Determine the sensor fixed loss pressure based on the preset initial fixed pressure and the sensor fixed detection pressure.
[0029] The initial fixing pressure is the clamping force feedback force when the temperature sensing surface of the temperature sensor is in perfect contact with the measured point. It is detected by the pressure sensor when the operator uses the fixing parts to fix the temperature sensor on the measured point. The initial fixing pressure reflects the good contact state between the temperature sensing surface of the temperature sensor and the measured point.
[0030] The sensor fixed loss pressure is the feedback force caused by the deterioration of the contact state between the temperature sensing surface of the temperature sensor and the measured point. It is obtained by the processing terminal calculating the difference between the initial fixed pressure and the sensor fixed detection pressure. The greater the sensor fixed loss pressure, the worse the contact state between the temperature sensing surface of the temperature sensor and the measured point, and the greater the detection temperature error output by the temperature sensor.
[0031] Step S102: Determine whether the fixed loss pressure of the sensor meets the requirements of the preset pressure deviation alarm threshold.
[0032] The pressure deviation alarm threshold is the minimum clamping force required to cause inaccurate temperature detection due to the contact between the temperature sensor's sensing surface and the measured point. The processing terminal selects a proportional coefficient based on the specific fixing method; for example, a proportional coefficient of 0.06 is used for bolt fixing, while a proportional coefficient of 0.12 is used for cable tie fixing. The product of the proportional coefficient and the initial fixing pressure is then calculated to obtain the pressure deviation alarm threshold. The requirement for the pressure deviation alarm threshold is that it must not be exceeded.
[0033] By processing the terminal to determine whether the fixed loss pressure of the sensor does not exceed the pressure deviation alarm threshold, it can be determined whether the deterioration of the fit between the temperature sensing surface of the temperature sensor and the measured point leads to inaccurate temperature detection.
[0034] Step S1021: If the condition is met, the temperature detected by the sensor is defined as the actual temperature of the measured point.
[0035] If the processing terminal determines that the fixed loss pressure of the sensor does not exceed the pressure deviation alarm threshold, it indicates that the pressure loss between the temperature sensing surface of the temperature sensor and the measured point is small, and the fit between the two is good, which will not cause the temperature sensor to detect the temperature inaccurately. Therefore, the temperature detected by the sensor is defined as the actual temperature of the measured point.
[0036] The actual temperature of the measured point is the actual temperature of the measured point in the distribution box. In this step, the operator directly recognizes the temperature detected by the sensor as the actual temperature of the measured point.
[0037] Step S1022: If not, analyze the fixed loss pressure of the sensor to determine the type of additional thermal resistance degradation at the measured point.
[0038] If the processing terminal determines that the fixed loss pressure of the sensor exceeds the pressure deviation alarm threshold, it indicates that there is a significant loss of clamping force between the temperature sensing surface of the temperature sensor and the measured point, and the fit between the two is poor. Therefore, the temperature detected by the sensor cannot be identified as the actual temperature of the measured point. Thus, it is necessary to analyze the fixed loss pressure of the sensor to determine the additional thermal resistance degradation type of the measured point, so as to provide data support for subsequent correction of the sensor's detected temperature based on the degradation type.
[0039] Additional thermal resistance degradation type is a classification of the reasons for the increase in thermal resistance between the sensing surface of the temperature sensor and the measured point. It includes two types: gap-type degradation and oxidation-type degradation. This is determined by the processing terminal after analyzing the sensor's fixed loss pressure. Specific methods are detailed in [reference needed]. Figure 2 The steps.
[0040] Gap-type degradation occurs when an air gap appears between the sensing surface of the temperature sensor and the measured point, leading to increased thermal resistance. Oxidation-type degradation occurs when an oxide layer forms at the measured point, resulting in increased thermal resistance.
[0041] Step S10221: Correct the sensor detection temperature according to the type of additional thermal resistance degradation to generate the actual temperature of the measured point.
[0042] In this step, the actual temperature of the measured point is defined the same as the time-temperature of the measured point in step S1021. The difference is that in this step, the actual temperature of the measured point is obtained by the processing terminal after correcting for the temperature detected by the sensor, taking into account the type of additional thermal resistance degradation. The specific method is described in [reference needed]. Figure 5 The steps.
[0043] Step S103: Determine the temperature rise warning report of the distribution box based on the actual temperature of the measured point and output the prompt.
[0044] The distribution box temperature rise early warning report is generated based on the distribution box temperature. It calculates the temperature rise by measuring the difference between the actual temperature and the initial temperature at the measured point, and then calculates the temperature rise rate by dividing the temperature difference between adjacent measured points by the time interval. The temperature rise and temperature rise rate are then compared with corresponding thresholds to determine the degree to which the threshold is exceeded, triggering different levels of warnings. In this embodiment, there are three levels of warnings: Level 1 is a warning of concern, where the temperature rise reaches 70% of the temperature rise threshold and the temperature rise rate reaches 1 degree Celsius per minute; Level 2 is a warning, where the temperature rise reaches 85% of the temperature rise threshold and the temperature rise rate reaches 2 degrees Celsius per minute; and Level 3 is a danger warning, where the temperature rise reaches the temperature rise threshold and the temperature rise rate reaches 5 degrees Celsius per minute. After the distribution box temperature rise early warning report is generated, it is sent to the central control screen or the maintenance personnel's terminal, prompting the maintenance personnel to perform timely maintenance and inspection.
[0045] Reference Figure 2 The steps for analyzing the fixed loss pressure of the sensor to determine the type of additional thermal resistance degradation at the measured point include: Step S200: Determine the pressure deviation ratio of the measured point based on the sensor's fixed loss pressure and initial fixed pressure.
[0046] The pressure deviation ratio is the proportion of pressure loss between the sensing surface of the temperature sensor and the measured point. It is obtained by the processing terminal by calculating the quotient between the fixed pressure loss of the sensor and the initial fixed pressure. The pressure deviation ratio classifies the degradation type according to the degree of pressure loss. Because the pressure loss caused by the loose fastener is greater, while the pressure loss caused by the oxidation of the measured point is smaller, the larger the pressure deviation ratio, the more serious the contact degradation between the sensing surface of the temperature sensor and the measured point.
[0047] Step S201: Determine the rate of change of the loss pressure at the measured point based on the fixed loss pressure of the sensor.
[0048] The rate of change of pressure loss is the rate of pressure loss between the sensing surface of the temperature sensor and the measured point. The greater the rate of change of pressure loss, the faster the contact degradation between the sensing surface of the temperature sensor and the measured point is. It is used to distinguish the type of degradation. The pressure loss of the air gap caused by the failure of the fastener is sudden, so the pressure loss rate is greater. On the other hand, the oxidation of the measured point is a slow process, so the pressure loss rate is smaller. It is obtained by the processing terminal by dividing the difference between the fixed pressure loss of the sensor corresponding to adjacent sampling times by the interval time.
[0049] Step S202: Obtain the percentage change in thermal response time and the trend of temperature change at the measured point.
[0050] The thermal response time change ratio is a quantified value representing the impact of contact degradation on the heat conduction path of the temperature sensor. This ratio reflects the deviation of the current temperature sensor's response speed to the temperature change at the measured point from its response speed in a perfectly fitted state. A larger thermal response time change ratio indicates more severe obstruction to heat conduction by the temperature sensor. The thermal response time change ratio distinguishes between different types of degradation—gap-type and oxidation-type—based on their impact on the heat conduction path. Gap-type degradation significantly increases thermal resistance and noticeably slows the response time, while oxidation-type degradation slightly increases thermal resistance with little change in response time. Specific methods for obtaining this ratio are detailed in [reference needed]. Figure 3 The steps.
[0051] The temperature change trend refers to the change in temperature deviation over time, including step changes and slow drift changes. The type of degradation is distinguished by the trend of temperature deviation change over time. Intermittent degradation is sudden, therefore the corresponding temperature deviation change is a step change, while oxidation degradation is slow, therefore the corresponding temperature deviation change is a slow drift change. For specific methods of obtaining this information, please refer to [reference needed]. Figure 4 The steps.
[0052] Step S203: Determine the type of additional thermal resistance degradation based on the pressure deviation ratio, the rate of change of loss pressure, the rate of change of thermal response time, and the temperature change trend.
[0053] In this step, the type of additional thermal resistance degradation is consistent with that in step S1022. It is determined by the processing terminal based on analysis of the pressure deviation ratio, the rate of change of pressure loss, the rate of change of thermal response time, and the temperature change trend. Specifically, gap-type degradation requires the following three conditions: First, the pressure deviation ratio is greater than 20% and the rate of change of pressure loss is greater than a set upper limit; second, the rate of change of thermal response time is greater than 50%; third, the temperature change trend exhibits a step-like change. Oxidation-type degradation requires the following three conditions: First, the pressure deviation ratio is less than 10% and the rate of change of pressure loss is less than a set lower limit; second, the rate of change of thermal response time is less than 20%; third, the temperature change trend exhibits a slow drifting change. If the degradation types indicated by the above three conditions are inconsistent, the degradation type is determined to be gap-type degradation, and temperature correction is performed based on the most conservative estimate.
[0054] Reference Figure 3 The steps for obtaining the percentage change in thermal response time at the measured point include: Step S300: Perform thermal excitation on the measured point in the distribution box according to the preset variable load current, and obtain the temperature-time change curve.
[0055] The variable load current is defined as the current in the distribution box circuit that exceeds the rated current by 20%. When the current sensor detects that the current in the distribution box circuit exceeds the rated current by 20%, the current at this time is defined as the variable load current.
[0056] When the load current changes, the measured point of the distribution box will experience temperature changes under the thermal excitation of the changing load current. At this time, the temperature-time change curve is detected to provide data support for the subsequent determination of the thermal response time of the temperature sensor.
[0057] The temperature-time variation curve is the curve of temperature change over time at the measured point when thermal excitation is performed with varying load current. Temperature detection and timing are started when the current in the distribution box circuit exceeds the rated current by 20%. The temperature-time variation curve is plotted with temperature as the vertical axis and time as the horizontal axis until the temperature change amplitude is less than 0.3 degrees Celsius, thus obtaining the complete temperature-time variation curve after thermal excitation.
[0058] Step S301: Determine the current thermal response time constant based on the temperature-time change curve.
[0059] The current thermal response time constant is the time required for the temperature sensor to detect the temperature at the measured point from its initial value to 63.2% of its final value. The current thermal response time constant reflects the speed at which the temperature sensor's sensing surface perceives the temperature change at the measured point. A larger current thermal response time constant indicates a greater thermal resistance between the sensing surface and the measured point. This is achieved by exponentially fitting the temperature-time change curve. In the formula, The excitation temperature at the measured point, The initial temperature of the measured point, The final temperature at the measured point. To incentivize time, Given the current thermal response time constant, the fitting parameters are extracted using the least squares method. This yields the current thermal response time constant.
[0060] Step S302: Determine the thermal response time change ratio of the measured point based on the current thermal response time constant and the preset initial thermal response time constant.
[0061] The initial thermal response time constant is the time required for the temperature sensor to detect the temperature at the measured point from the initial value to 63.2% of the final value under the initial installation state. It is consistent with the calibration process of the current thermal response time constant. The initial thermal response time constant reflects the response speed of the temperature sensor under healthy contact conditions. As a benchmark, it is compared with the current response time constant to determine the degree of influence of contact degradation on heat conduction.
[0062] The thermal response time change ratio in this step is consistent with the thermal response time change ratio in step S202, and is obtained by the processing terminal by calculating the quotient of the difference between the current thermal response time constant and the initial thermal response time constant and the initial thermal response time constant.
[0063] Reference Figure 4 The steps to obtain the temperature change trend of the measured point include: Step S400: Thermally excite the measured point in the distribution box and obtain the steady-state current value and steady-state detection temperature.
[0064] In order to determine the temperature change trend of the measured point, it is necessary to first thermally excite the measured point of the distribution box. By adjusting the excitation current, the measured point will produce a temperature change, and the steady-state current value and steady-state detection temperature at this time will be detected to provide data support for subsequent determination of the temperature change trend of the measured point.
[0065] The steady-state current value is the effective value of the current at the measured point when the distribution box is running stably. By adjusting the load of the distribution box, the current is adjusted, and a current sensor is used to detect the real-time current. When the current change value approaches the minimum value, the real-time current at this time is determined as the steady-state current value.
[0066] The steady-state detection temperature is the temperature value of the measured point when the distribution box is running stably. When a steady-state current value is detected, the value detected by the temperature sensor at this time is determined as the steady-state detection temperature.
[0067] Step S401: Determine the estimated true temperature of the measured point based on the steady-state current value and the preset comprehensive thermal coefficient.
[0068] The comprehensive thermal coefficient is a quantitative value representing the combined effect of conductor resistance heating, convective heat dissipation, and radiative heat dissipation. It is a thermal parameter characterizing the temperature rise of the measured point relative to the ambient temperature under a unit load current square. For every 1 ampere of current squared passing through the measured point, the temperature of the measured point rises relative to the ambient temperature by the corresponding value of the comprehensive thermal coefficient. The comprehensive thermal coefficient is used to estimate the true temperature of the measured point. The heating power of the measured point is the square of the current multiplied by the conductor resistance. Under steady state, heating equals heat dissipation, and heat dissipation is approximately proportional to the temperature rise. Therefore, the temperature rise is proportional to the square of the current, and the proportionality coefficient is the comprehensive thermal coefficient. The specific calibration process is as follows: In the initial stage of installation, the temperature of the measured point is measured using a temperature sensor to obtain the true temperature. Then, the load current and ambient temperature are detected at this time. The temperature is obtained by calculating the quotient between the difference between the true temperature and the ambient temperature and the square of the load current.
[0069] The true temperature estimate is the temperature estimate of the measured point under the excitation of the steady-state current value. The processing terminal calculates the product of the steady-state current value and the comprehensive thermal coefficient to obtain the temperature rise value relative to the ambient temperature. Then, the ambient temperature is detected, and the temperature rise value is added to obtain the true temperature estimate value.
[0070] Step S402: Determine the actual temperature deviation of the measured point based on the steady-state detection temperature and the estimated true temperature.
[0071] The actual temperature deviation is the amount of deviation caused by contact deterioration, which results in the temperature sensor reading being lower than the true value. It is obtained by the processing terminal calculating the difference between the estimated true temperature and the steady-state detected temperature. The larger the actual temperature deviation, the greater the influence of the thermal resistance between the sensing surface and the measured point on heat conduction, and the lower the temperature measurement accuracy.
[0072] Step S403: Plot the current change-temperature deviation curve based on the steady-state current value and the actual temperature deviation.
[0073] The current change-temperature deviation curve is a curve showing the temperature deviation as a function of the square of the current. It is obtained by collecting multiple steady-state current values and their corresponding actual temperature deviations, plotting the curve with the square of the steady-state current value as the abscissa and the actual temperature deviation as the ordinate.
[0074] Step S404: Determine the temperature change trend of the measured point based on the current change-temperature deviation curve.
[0075] In this step, the temperature change trend is consistent with the temperature change trend in step S202. The processing terminal analyzes the curve change law of the current change-temperature deviation curve. If the temperature deviation jumps from zero to a certain stable value and remains stable, it is a step change. If the temperature deviation increases slowly and monotonically, it is determined to be a slow drift change.
[0076] Reference Figure 5 The steps for correcting the sensor's detected temperature based on the type of additional thermal resistance degradation to generate the actual temperature at the measured point include: Step S500: Determine the current additional thermal resistance of the measured point based on the type of additional thermal resistance degradation.
[0077] The current additional thermal resistance refers to the increased thermal resistance caused by contact degradation between the measured point and the temperature sensor. This additional thermal resistance characterizes the ability to impede heat conduction between the measured point and the temperature sensor. A higher additional thermal resistance indicates more severe contact degradation and a greater temperature measurement deviation. It is determined by the processing terminal based on the type of additional thermal resistance degradation; specific methods are described in [reference needed]. Figure 6 The steps.
[0078] Step S501: Obtain the total thermal resistance of the sensor and the ambient temperature of the power distribution box.
[0079] The total thermal resistance of the sensor is the total heat conduction resistance that prevents the temperature sensor from dissipating heat to the environment. It includes both natural convection heat transfer and thermal radiation heat transfer. The greater the total thermal resistance of the sensor, the more difficult it is for the temperature sensor to dissipate heat to the environment. The specific method for obtaining this resistance is as follows: .
[0080] In the formula, The total thermal resistance of the sensor is [missing information]. The natural convection heat transfer coefficient is typically taken as 5 to 10 inside the distribution box. , The heat dissipation area of the temperature sensor's outer surface is determined by the operator through measurement of the sensor's geometric dimensions. For the emissivity of the sensor housing, taking 0.85 as an example, This is the Stefan-Boltzmann constant. For the sensor to detect temperature, The ambient temperature of the distribution box.
[0081] The ambient temperature of the distribution box is the temperature inside the distribution box, which is detected by an ambient temperature sensor installed inside the distribution box.
[0082] Step S502: Determine the temperature correction factor based on the current additional thermal resistance and the total heat dissipation thermal resistance of the sensor.
[0083] The temperature correction coefficient is a quantitative value that characterizes the degree of influence of the additional thermal resistance on the accuracy of the temperature sensor. It is obtained by the processing terminal from the ratio between the current additional thermal resistance and the total heat dissipation thermal resistance of the sensor. That is, the greater the weight of the additional thermal resistance introduced by contact degradation in the total thermal resistance link of the sensor, the more serious the impact on the accuracy of temperature measurement, and the greater the amount of temperature compensation required. The temperature correction coefficient converts the influence of the additional thermal resistance on temperature accuracy into a proportionality coefficient between the sensor reading and the actual temperature.
[0084] Step S503: Determine the temperature correction range based on the temperature detected by the sensor and the ambient temperature of the distribution box.
[0085] The temperature correction range is the effective temperature difference that drives the heat flow during the heat dissipation process of the temperature sensor to the distribution box environment. It is obtained by the processing terminal calculating the difference between the temperature detected by the sensor and the temperature of the distribution box environment. The larger the temperature correction range, the greater the current heat flow on the surface and the greater the temperature measurement deviation caused by contact deterioration.
[0086] Step S504: Calculate the product of the temperature correction factor and the temperature correction range to generate the actual corrected temperature.
[0087] The actual correction temperature is the underestimation of the temperature on the sensor reading caused by the additional thermal resistance due to contact degradation, i.e., the temperature value that needs to be compensated. The actual correction temperature characterizes the temperature drop caused by the thermal resistance on both sides of the measured point and the sensing surface. It is obtained by the processing terminal by multiplying the temperature correction coefficient and the temperature correction range. Under steady-state conditions, the heat flow through the contact surface is equal to the heat dissipation from the sensor to the environment. Therefore, the heat flow is equal to the temperature difference between the sensor and the environment divided by the total heat dissipation thermal resistance. The temperature difference on both sides of the contact surface is the heat flow multiplied by the additional thermal resistance. Combining the two equations, we get that the temperature difference on both sides of the contact surface is equal to the temperature difference between the sensor and the environment divided by the total heat dissipation thermal resistance, multiplied by the additional thermal resistance. Therefore, the quotient of the additional thermal resistance and the total heat dissipation thermal resistance is the correction coefficient, while the temperature difference between the sensor and the environment is the correction range.
[0088] Step S505: Calculate the sum of the sensor-detected temperature and the actual corrected temperature to generate the actual temperature of the measured point.
[0089] In this step, the actual temperature of the measured point is consistent with the actual temperature of the measured point in step S10221, and is obtained by the processing terminal by calculating the sum of the sensor-detected temperature and the actual corrected temperature.
[0090] Reference Figure 6 The steps for determining the current additional thermal resistance at the test point based on the type of additional thermal resistance degradation include: Step S600: Determine whether the additional thermal resistance degradation type is a preset gap-type degradation type or a preset oxidation-type degradation type.
[0091] The intermittent degradation type and oxidation degradation type in this step are consistent with the intermittent degradation type and oxidation degradation type disclosed in step S1022, and will not be described again here.
[0092] By processing the terminal to determine whether the additional thermal resistance degradation type is gap-type or oxidation-type, the current additional thermal resistance of the measured point can be calculated.
[0093] Step S601: If it is a gap-type degradation type, determine the current additional thermal resistance of the measured point based on the sensor fixed loss pressure.
[0094] If the processing terminal determines that the additional thermal resistance degradation type is gap-type degradation, it indicates that there is an air gap between the sensing surface and the measured point. The gap thickness has a definite mechanical relationship with the pressure loss. Therefore, the current additional thermal resistance can be deduced from the sensor's fixed pressure loss. The specific method is described in [reference needed]. Figure 7 The steps.
[0095] Step S602: If it is an oxidation-type degradation, obtain the current steady-state current value.
[0096] If the processing terminal determines that the additional thermal resistance degradation type is oxidation type, it indicates that oxidation has occurred at the measured point. In this case, the additional thermal resistance needs to be determined by the thermal resistance inversion method, and therefore the current steady-state current value is detected.
[0097] The current steady-state current value is the effective current value of the measured point in the power distribution, which is obtained by the current sensor.
[0098] Step S6021: Analyze the current steady-state current value, the total thermal resistance of the sensor, and the ambient temperature of the distribution box to generate the current additional thermal resistance of the measured point.
[0099] After determining the current steady-state current value, the current additional thermal resistance is determined by analyzing the current steady-state current value, the total heat dissipation thermal resistance of the sensor, and the ambient temperature of the distribution box. The specific method is described in [reference needed]. Figure 8 The steps.
[0100] Reference Figure 7 The steps for determining the current additional thermal resistance at the measured point based on the sensor's fixed loss pressure include: Step S700: Determine the current gap thickness at the measured point based on the sensor's fixed loss pressure and the preset fixed equivalent stiffness.
[0101] Among them, the fixed equivalent stiffness is the equivalent elastic stiffness of the fastener in the axial direction, which reflects the force required for the fastener to produce a unit deformation in the clamping direction. The fixed equivalent stiffness treats the fastener as a spring, thus making the thickness of the gap equivalent to the compression reduction of the spring. The determination method is as follows: for bolts, the equivalent stiffness is the product of the elastic modulus of the bolt material and the cross-sectional area of the bolt shank divided by the effective length of the bolt; for cable ties, it is calibrated by applying a known displacement during installation and measuring the force change.
[0102] The current gap thickness is the thickness of the air gap between the temperature sensing surface and the measured point. The larger the current gap thickness, the more severe the separation between the temperature sensing surface and the measured point, and the greater the resistance of the air layer to heat conduction. It is obtained by the quotient of the fixed loss pressure of the sensor and the fixed equivalent stiffness. When the fixing part is initially installed, an initial fixing pressure is generated. When a gap occurs, the fixing part reduces the compression by the gap thickness. According to Hooke's Law, the pressure reduction is equal to the equivalent stiffness multiplied by the compression reduction. Therefore, the compression reduction is equal to the quotient of the sensor's fixed loss pressure and the fixed equivalent stiffness.
[0103] Step S701: Determine the current additional thermal resistance of the measured point based on the current gap thickness, the preset air thermal conductivity, and the preset effective heat transfer area.
[0104] Among them, the thermal conductivity of air is a parameter that reflects the ability of air to conduct heat. It reflects the energy of an air layer of unit thickness and unit area to transfer heat under a unit temperature difference. It is the root cause of severe temperature measurement deviation caused by interstitial deterioration.
[0105] The effective heat transfer area is the area actually covered by the sensing surface at the measured point, reflecting the effective cross-sectional size of the heat flow from the measured point to the sensor.
[0106] The current additional thermal resistance in this step is the same as the current additional thermal resistance in step S601. It is obtained by the processing terminal by calculating the current gap thickness divided by the product of the air thermal conductivity and the effective heat transfer area. According to Fourier's law of thermal conductivity, the heat flow through a plate with a certain thickness, area and thermal conductivity is the product of thermal conductivity, area and temperature difference divided by the thickness. The thermal resistance is the temperature difference divided by the heat flow, which is equal to the thickness divided by the product of thermal conductivity and area.
[0107] Reference Figure 8 The steps to generate the current additional thermal resistance of the measured point by analyzing the current steady-state current value, the total heat dissipation thermal resistance of the sensor, and the ambient temperature of the distribution box include: Step S800: Determine the estimated surface temperature of the measured point based on the current steady-state current value and the preset comprehensive thermal coefficient.
[0108] The overall thermal coefficient in this step is the same as that in step S401, and will not be repeated here.
[0109] The surface temperature estimate is the estimated surface temperature of the measured point. The temperature rise is obtained by multiplying the square of the current steady-state current value and the comprehensive thermal coefficient by the processing terminal. Then, the sum of the temperature rise and the ambient temperature of the distribution box is calculated to obtain the surface temperature estimate.
[0110] Step S801: Analyze the surface temperature estimate, sensor detection temperature, and distribution box ambient temperature to determine the thermal resistance correction coefficient.
[0111] The thermal resistance correction coefficient is a dimensionless intermediate parameter representing the weight of the oxide layer's thermal resistance in the sensor's total thermal resistance chain. It is the ratio between the temperature drop across the oxide layer and the temperature drop from the sensor to the environment. The larger this value, the greater the relative thermal resistance of the oxide layer to the heat dissipation thermal resistance, and the more severe the oxidation degradation. It is obtained by calculating the difference between the estimated surface temperature and the sensor's detected temperature, divided by the difference between the sensor's detected temperature and the ambient temperature of the distribution box. Under steady-state conditions, the heat flow transmitted to the sensor through the oxide layer is equal to the heat flow dissipated from the sensor to the environment. That is, the temperature difference across the oxide layer divided by the additional thermal resistance is equal to the sensor's ambient temperature difference divided by the total heat dissipation thermal resistance. Therefore, the correction coefficient is the additional thermal resistance divided by the total heat dissipation thermal resistance, which is the temperature difference across the oxide layer divided by the sensor's ambient temperature difference.
[0112] Step S802: Calculate the product of the thermal resistance correction factor and the total heat dissipation thermal resistance of the sensor to generate the current additional thermal resistance of the measured point.
[0113] In this process, after determining the thermal resistance correction coefficient, the current additional thermal resistance is obtained by calculating the product of the thermal resistance correction coefficient and the total heat dissipation thermal resistance of the sensor.
[0114] Based on the same inventive concept, embodiments of this application provide a multi-sensor temperature rise early warning system for a distribution box, including: The acquisition module is used to acquire sensor detection temperature, sensor fixed detection pressure, thermal response time change ratio, temperature change trend, steady-state current value, steady-state detection temperature, sensor total heat dissipation thermal resistance, distribution box ambient temperature, and current steady-state current value. A memory for storing a program for a multi-sensor temperature rise early warning method for a power distribution box; The processor can load and execute programs in memory to implement a multi-sensor temperature rise early warning method for electrical distribution boxes.
[0115] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0116] This application provides a computer-readable storage medium storing a computer program that can be loaded by a processor and executed as a method for early warning of multi-sensor temperature rise in a distribution box.
[0117] Computer storage media include, for example, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media that can store program code.
[0118] Based on the same inventive concept, embodiments of this application provide a smart terminal, including a memory and a processor, wherein the memory stores a computer program that can be loaded and executed by the processor to provide a multi-sensor temperature rise early warning method for a power distribution box.
[0119] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0120] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.
Claims
1. A multi-sensor temperature rise early warning method for distribution boxes, characterized in that, include: Obtain the sensor-detected temperature and sensor-fixed detection pressure at the measured point in the distribution box; The sensor fixing loss pressure is determined based on the preset initial fixing pressure and the sensor fixing detection pressure. Determine whether the fixed loss pressure of the sensor meets the preset pressure deviation alarm threshold. If the conditions are met, the temperature detected by the sensor is defined as the actual temperature of the measured point. If not, the fixed loss pressure of the sensor is analyzed to determine the type of additional thermal resistance degradation at the measured point. The sensor's detected temperature is corrected based on the type of additional thermal resistance degradation to generate the actual temperature at the measured point. The distribution box temperature rise early warning report is generated and a prompt is output based on the actual temperature of the measured point.
2. The multi-sensor temperature rise early warning method for a distribution box according to claim 1, characterized in that, The steps for analyzing the fixed loss pressure of the sensor to determine the type of additional thermal resistance degradation at the measured point include: The pressure deviation ratio at the measured point is determined based on the sensor's fixed loss pressure and initial fixed pressure. The rate of change of the loss pressure at the measured point is determined based on the fixed loss pressure of the sensor. Obtain the percentage change in thermal response time and the trend of temperature change at the measured point; The type of additional thermal resistance degradation is determined based on the pressure deviation ratio, the rate of change of loss pressure, the rate of change of thermal response time, and the temperature change trend.
3. The multi-sensor temperature rise early warning method for a distribution box according to claim 2, characterized in that, The steps to obtain the percentage change in thermal response time at the measured point include: Thermal excitation is applied to the measured points in the distribution box based on the preset variable load current, and the temperature-time change curve is obtained. Determine the current thermal response time constant based on the temperature-time change curve; The thermal response time change ratio of the measured point is determined based on the current thermal response time constant and the preset initial thermal response time constant.
4. The multi-sensor temperature rise early warning method for a distribution box according to claim 2, characterized in that, The steps to obtain the temperature change trend of the measured point include: Thermal excitation is applied to the measured points in the distribution box, and steady-state current and steady-state detection temperature are obtained; The true temperature estimate of the measured point is determined based on the steady-state current value and the preset comprehensive thermal coefficient. The actual temperature deviation at the measured point is determined based on the steady-state detection temperature and the estimated actual temperature. Plot the current change-temperature deviation curve based on the steady-state current value and the actual temperature deviation. The temperature change trend at the measured point is determined based on the current change-temperature deviation curve.
5. The multi-sensor temperature rise early warning method for a distribution box according to claim 1, characterized in that, The steps for correcting the sensor's detected temperature based on the type of additional thermal resistance degradation to generate the actual temperature at the measured point include: The current additional thermal resistance at the test point is determined based on the type of additional thermal resistance degradation. Obtain the total thermal resistance of the sensor and the ambient temperature of the power distribution box; The temperature correction factor is determined based on the current additional thermal resistance and the total heat dissipation thermal resistance of the sensor. The temperature correction range is determined based on the temperature detected by the sensor and the ambient temperature of the distribution box. Calculate the product of the temperature correction factor and the temperature correction range to generate the actual corrected temperature; Calculate the sum of the sensor-detected temperature and the actual corrected temperature to generate the actual temperature of the measured point.
6. The multi-sensor temperature rise early warning method for a distribution box according to claim 5, characterized in that, The steps for determining the current additional thermal resistance at the test point based on the type of additional thermal resistance degradation include: Determine whether the additional thermal resistance degradation type is the preset gap type or the preset oxidation type. If it is a gap-type degradation type, the current additional thermal resistance of the measured point is determined based on the sensor's fixed loss pressure. If the degradation type is oxidation, then obtain the current steady-state current value; The current steady-state current value, the total thermal resistance of the sensor, and the ambient temperature of the distribution box are analyzed to generate the current additional thermal resistance of the measured point.
7. The multi-sensor temperature rise early warning method for a distribution box according to claim 6, characterized in that, The steps for determining the current additional thermal resistance at the measured point based on the sensor's fixed loss pressure include: The current gap thickness at the measured point is determined based on the sensor's fixed loss pressure and the preset fixed equivalent stiffness. The current additional thermal resistance of the measured point is determined based on the current gap thickness, the preset air thermal conductivity, and the preset effective heat transfer area.
8. The multi-sensor temperature rise early warning method for a distribution box according to claim 7, characterized in that, The steps to generate the current additional thermal resistance of the measured point by analyzing the current steady-state current value, the total thermal resistance of the sensor, and the ambient temperature of the distribution box include: The surface temperature estimate of the measured point is determined based on the current steady-state current value and the preset comprehensive thermal coefficient. The surface temperature estimate, sensor detection temperature, and distribution box ambient temperature are analyzed to determine the thermal resistance correction coefficient. Calculate the product of the thermal resistance correction factor and the total thermal resistance of the sensor to generate the current additional thermal resistance of the measured point.
9. A multi-sensor temperature rise early warning system for a distribution box, characterized in that, include: The acquisition module is used to acquire the sensor-detected temperature and the sensor-fixed detection pressure; A memory for storing a program for a multi-sensor temperature rise early warning method for a distribution box as described in any one of claims 1 to 8; The processor and the program in the memory can be loaded and executed by the processor to implement the multi-sensor temperature rise early warning method for a distribution box as described in any one of claims 1 to 8.