A monitoring method and system of a photovoltaic system, an intelligent terminal and a storage medium

Abstract

The application relates to a photovoltaic system monitoring method, a system, an intelligent terminal and a storage medium, and relates to the field of photovoltaic technology. The method comprises the following steps: collecting temperature data of each photovoltaic junction box to form a temperature data set, wherein the temperature data is derived from a junction terminal of the photovoltaic junction box; calculating a reference temperature according to the temperature data set; judging whether there is an abnormal temperature in the temperature data set according to the reference temperature, wherein the difference between the abnormal temperature and the reference temperature is greater than a preset temperature difference; if there is, regarding the photovoltaic junction box corresponding to the abnormal temperature as an abnormal photovoltaic junction box; and closing a bus branch where the abnormal photovoltaic junction box is located. The application has the effect of improving the operation safety of a photovoltaic system.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a monitoring method, system, smart terminal and storage medium for a photovoltaic system. Background Technology

[0002] In photovoltaic (PV) systems, the PV junction box is a crucial component connecting solar panels to external wiring, ensuring the safe and stable discharge of direct current (DC) generated by the PV modules. Therefore, ensuring the stable operation of the PV junction box is of paramount importance.

[0003] The relevant technologies for monitoring photovoltaic junction boxes mainly adopt voltage and current detection methods. That is, after collecting electrical parameters at the branch or module level, the electrical parameters are compared with preset standard parameters to determine whether there is an open circuit, short circuit or power abnormality.

[0004] Regarding the aforementioned technologies, when a photovoltaic system is working, the photovoltaic junction box will accumulate heat. When the temperature is too high, it may cause the photovoltaic junction box to restart or even burn out. Summary of the Invention

[0005] To improve the operational safety of photovoltaic systems, this application provides a monitoring method, system, smart terminal, and storage medium for photovoltaic systems.

[0006] In a first aspect, this application provides a monitoring method, system, smart terminal, and storage medium for a photovoltaic system, employing the following technical solution: A method for monitoring a photovoltaic system, comprising: Temperature data of each photovoltaic junction box is collected to form a temperature data set, wherein the temperature data originates from the wiring terminals of the photovoltaic junction box; Calculate the reference temperature based on the temperature data set; Based on the reference temperature, determine whether there is an abnormal temperature in the temperature data set, wherein the difference between the abnormal temperature and the reference temperature is greater than a preset temperature difference. If it exists, the photovoltaic junction box corresponding to the abnormal temperature will be regarded as the abnormal photovoltaic junction box; Shut down the bus branch where the abnormal photovoltaic junction box is located.

[0007] By adopting the above technical solution, the temperature data of each junction box terminal is used as the monitoring object. After calculating the reference temperature, it is compared one by one. Junction boxes with temperature deviations exceeding the preset threshold are identified as abnormal and their corresponding branches are shut down. This method realizes automated closed-loop monitoring and fault isolation of the photovoltaic system's operating thermal state. It can promptly cut off the circuit when abnormal temperature rise occurs in the junction box, effectively preventing the escalation of faults and fire hazards, and improving the operational safety of the photovoltaic system.

[0008] Optionally, the ambient temperature of the photovoltaic system can be collected; Obtain the location and environmental information of the photovoltaic system; Based on the location information and the environmental information, the ambient temperature is adjusted to obtain an updated ambient temperature; Calculate the mean of the temperature data set to obtain the average temperature. The updated ambient temperature and the average temperature are weighted and calculated to obtain the reference temperature.

[0009] By adopting the above technical solution, the determination of the reference temperature is based not only on the average temperature of each junction box, but also on the updated ambient temperature adjusted for location and environmental information, and the two are combined through a weighted average. This allows the reference temperature to comprehensively reflect the normal thermal state of the junction box under current operating conditions, avoiding misjudgments caused by relying solely on the average or ambient temperature, and improving the accuracy of abnormal temperature identification and adaptability to different installation environments.

[0010] Optionally, the latitude and altitude data in the location information can be obtained; Based on the latitude data and the current date, calculate the solar altitude angle, and determine the solar radiation intensity factor based on the solar altitude angle; The atmospheric pressure correction coefficient is obtained using the altitude data, and the solar radiation intensity factor is corrected using the atmospheric pressure correction coefficient to obtain the corrected radiation factor; Obtain cloud cover information from the environmental information, determine the cloud attenuation coefficient based on the cloud cover information, and calculate the product of the corrected radiation factor and the cloud attenuation coefficient to obtain the effective radiation-induced temperature increment. Obtain the wind speed from the environmental information, and calculate the reduction in air-cooled temperature based on the wind speed; The updated ambient temperature is obtained by summing the ambient temperature, the effective radiation-induced temperature increment, and the air-cooled temperature reduction.

[0011] By adopting the above technical solution, the adjustment of ambient temperature comprehensively takes into account the effects of multiple factors such as solar radiation, cloud cover attenuation, and wind cooling. Radiation intensity is calculated using latitude and altitude, and the radiation increment is corrected by combining cloud cover data. Wind speed is used to quantify wind cooling, making the updated ambient temperature closer to the actual perceived temperature of the photovoltaic junction box. This further improves the representativeness of the reference temperature and the reliability of subsequent anomaly detection.

[0012] Optionally, determine the remaining temperatures in the temperature data set other than the abnormal temperatures; Determine the historical temperature data corresponding to the remaining temperature; The historical temperature data were statistically processed to obtain standard historical temperature data; The standard historical temperature data is processed to obtain a standard historical temperature curve, and the historical temperature data is processed to obtain a historical temperature curve. Calculate the similarity between the standard historical temperature curve and the historical temperature curve to obtain the first similarity. Determine target similarities that are less than the first similarity threshold from the first similarity; The photovoltaic junction box corresponding to the target similarity is regarded as the metastable photovoltaic junction box; Shut down the bus branch where the metastable photovoltaic junction box is located.

[0013] By employing the above technical solution, after excluding identified abnormal temperatures, the historical trends of the remaining temperature data are further analyzed. By comparing the similarity between the actual historical temperature curve and the standard historical temperature curve, metastable junction boxes whose temperature evolution patterns deviate from the normal are identified and shut down. This method can proactively detect potential faults that are still in the development stage, have not yet triggered the temperature threshold, but have already shown a deteriorating trend, achieving an upgrade from passive alarm to proactive early warning.

[0014] Optionally, the historical temperature curve corresponding to the target similarity can be used as a candidate historical temperature curve. The selection step includes selecting the i-th candidate historical temperature curve from the candidate historical temperature curves, where i is an integer with an initial value of 1. A negative delay step is performed, wherein the negative delay step performs negative delay processing on the i-th candidate historical temperature curve according to the j-th delay length to obtain an updated historical temperature curve, where j is an integer with an initial value of 1; The calculation step includes calculating the similarity between the standard historical temperature curve and the updated temperature curve to obtain a second similarity. If the second similarity is greater than or equal to the second similarity threshold, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is used as a substitute photovoltaic junction box; i is updated to i+1, and the selection step is returned to be executed. If the second similarity is less than the second similarity threshold, then determine whether the j-th time extension is greater than the time extension threshold; If so, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is taken as the metastable photovoltaic junction box; i is updated to i+1, and the selection step is returned to be executed; If not, update j to j+1 and repeat the negative delay step and the calculation step.

[0015] By adopting the above technical solution, negative time delay analysis is introduced into the process of identifying metastable junction boxes. By progressively adjusting the time offset of historical temperature curves, their similarity to the standard curve is recalculated. If the similarity meets the requirements at a certain time delay, it is classified as a substitute junction box. This method can identify potential faults where time deviations occur in abnormal temperature patterns, refines the judgment logic for metastable states, and reduces false shutdowns.

[0016] Optionally, the temperature data corresponding to the substitute photovoltaic junction box is recorded as the substitute temperature data; Set the historical time period based on the current time; The historical substitute temperature corresponding to the historical time period is determined from the substitute temperature data, and the current substitute temperature corresponding to the current moment is determined from the substitute temperature data. Calculate the slope of each time period within the historical period based on the historical replacement temperature; The maximum slope is obtained by taking the maximum value among the slopes. Calculate the future predicted temperature based on the maximum slope, the j-th time extension, and the current substitute temperature; If the difference between the predicted future temperature and the reference temperature is greater than the preset temperature difference, then the bus branch where the substitute photovoltaic junction box is located is shut down.

[0017] By employing the above technical solution, for backup junction boxes that have not yet triggered shutdown conditions, the maximum slope for each time period is calculated using their historical temperature data, and the future temperature is predicted by combining the time extension and the current temperature. If the predicted temperature will exceed the allowable range, the branch circuit containing that box is shut down in advance. This method achieves a proactive response to impending faults, taking protective measures before the fault actually occurs, further enhancing the system's active safety protection capabilities.

[0018] Optionally, if the difference between the predicted future temperature and the reference temperature is less than or equal to the preset temperature difference, the substitute photovoltaic junction box is marked as an observation photovoltaic junction box. The continuous temperature data of the photovoltaic junction box during the preset observation period are obtained to form an observation temperature sequence; Perform a second-order difference operation on the observed temperature sequence to obtain a temperature change acceleration sequence; Extract the maximum acceleration value from the temperature change acceleration sequence; If the maximum acceleration value is greater than the preset acceleration threshold, the observed photovoltaic junction box is determined to be an abnormal photovoltaic junction box, and the bus branch in which it is located is shut down; If the maximum acceleration value is less than or equal to the preset acceleration threshold, the observed photovoltaic junction box is redefined as the metastable photovoltaic junction box, and the execution of the negative time delay step and the calculation step is returned.

[0019] By employing the above technical solution, backup junction boxes whose predicted temperatures do not exceed the limit are marked as observation targets. The maximum acceleration value of temperature change is extracted by analyzing the second-order difference of temperature changes within a preset observation period. If the acceleration exceeds the threshold, it indicates a rapid deterioration of the temperature, immediately escalating to an anomaly and shutting down the branch; otherwise, it reverts to a metastable state for continued monitoring. This dynamic evaluation mechanism effectively prevents the risk of sudden temperature changes, balancing safety and the system's continuous operation capability.

[0020] Secondly, this application provides a monitoring system for a photovoltaic system, which adopts the following technical solution: A monitoring system for a photovoltaic system, comprising: The acquisition module is used to acquire temperature data; A memory for storing the program of the monitoring method for the photovoltaic system; The processor and the program in the memory can be loaded and executed by the processor to implement the monitoring method of the photovoltaic system.

[0021] By adopting the above technical solution, the temperature data of each junction box terminal is used as the monitoring object. After calculating the reference temperature, it is compared one by one. Junction boxes with temperature deviations exceeding the preset threshold are identified as abnormal and their corresponding branches are shut down. This method realizes automated closed-loop monitoring and fault isolation of the photovoltaic system's operating thermal state. It can promptly cut off the circuit when abnormal temperature rise occurs in the junction box, effectively preventing the escalation of faults and fire hazards, and improving the operational safety of the photovoltaic system.

[0022] Thirdly, this application provides a smart terminal, which adopts the following technical solution: A smart terminal includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed as described in any of the preceding methods.

[0023] Fourthly, this application provides a computer storage medium capable of storing corresponding programs, which facilitates improvements in the operational safety of photovoltaic systems, and adopts the following technical solution: A computer-readable storage medium storing a computer program that can be loaded by a processor and executed as a monitoring method for any of the aforementioned photovoltaic systems.

[0024] In summary, this application includes at least one of the following beneficial technical effects: Using the temperature data of each junction box terminal as the monitoring object, a reference temperature is calculated and compared one by one. Junction boxes with temperature deviations exceeding a preset threshold are identified as abnormal and their corresponding branches are shut down. This method realizes automated closed-loop monitoring and fault isolation of the photovoltaic system's operating thermal state. It can promptly cut off the circuit when abnormal temperature rise occurs in the junction box, effectively preventing the escalation of faults and fire hazards, and improving the operational safety of the photovoltaic system. The reference temperature is determined not only based on the average temperature of each junction box, but also by incorporating an updated ambient temperature adjusted for location and environmental information, and combining the two through a weighted average. This allows the reference temperature to comprehensively reflect the normal thermal state of the junction box under current operating conditions, avoiding misjudgments caused by relying solely on the average or ambient temperature, and improving the accuracy of abnormal temperature identification and adaptability to different installation environments. The adjustment of ambient temperature comprehensively takes into account the effects of multiple factors such as solar radiation, cloud cover attenuation, and wind cooling. Radiation intensity is calculated by latitude and altitude, and the radiation increment is corrected by cloud cover. Wind speed is used to quantify wind cooling, making the updated ambient temperature closer to the actual perceived temperature of the photovoltaic junction box. This further improves the representativeness of the reference temperature and the reliability of subsequent anomaly detection. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating a photovoltaic system monitoring method disclosed in an embodiment of this application.

[0026] Figure 2 This is a flowchart illustrating a method for calculating a reference temperature disclosed in an embodiment of this application.

[0027] Figure 3 This is a flowchart illustrating a method for calculating updated ambient temperature disclosed in an embodiment of this application.

[0028] Figure 4 This is a flowchart illustrating a method for troubleshooting potential faults in a photovoltaic junction box, as disclosed in an embodiment of this application.

[0029] Figure 5 This is a flowchart illustrating a method for verifying a metastable photovoltaic junction box disclosed in an embodiment of this application.

[0030] Figure 6 This is a flowchart illustrating a predictive processing method for a replacement photovoltaic junction box disclosed in an embodiment of this application.

[0031] Figure 7 This is a flowchart illustrating an observation and processing method for a replacement photovoltaic junction box disclosed in an embodiment of this application.

[0032] Figure 8 This is a schematic diagram of a photovoltaic system monitoring system disclosed in an embodiment of this application. Detailed Implementation

[0033] 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.

[0034] This application discloses a monitoring method for a photovoltaic system. (Refer to...) Figure 1 The method includes: Step S101: Collect temperature data for each photovoltaic junction box to form a temperature data set. The temperature data comes from the wiring terminals of the photovoltaic junction box.

[0035] A photovoltaic (PV) junction box is an electrical connection device installed on the back of a PV module, used to collect and conduct the direct current generated by the PV cell string. A terminal block is a metal connector inside the PV junction box used to lock and connect the busbars; it includes male and female terminals.

[0036] In a photovoltaic system, photovoltaic junction boxes are connected in series, with the male terminal of one photovoltaic junction box connected to the female terminal of the next photovoltaic junction box.

[0037] The temperature data set consists of temperature data from different photovoltaic junction boxes.

[0038] In this application, a temperature sensor is installed on the male terminal of the photovoltaic junction box, and the temperature data collected in this step comes from the aforementioned temperature sensor.

[0039] Step S102: Calculate the reference temperature based on the temperature data set.

[0040] The reference temperature is a standard used to measure whether the temperature of a photovoltaic junction box is normal. In real-world scenarios, photovoltaic junction boxes continuously accumulate heat during operation, and the applicant has found that the connection points of the terminals of two photovoltaic junction boxes are the easiest places for heat to accumulate. Therefore, this application will use temperature data from the terminals to determine whether the photovoltaic junction box is working properly.

[0041] Step S103: Based on the reference temperature, determine whether there is an abnormal temperature in the temperature data set. The difference between the abnormal temperature and the reference temperature is greater than the preset temperature difference.

[0042] The preset temperature difference is a threshold for judging whether the temperature data is abnormal.

[0043] Each temperature value in the temperature dataset is compared with a reference temperature. If the absolute value of the difference between a temperature value and the reference temperature is greater than a preset temperature difference, the temperature is determined to be an abnormal temperature.

[0044] Step S104: If it exists, then the photovoltaic junction box corresponding to the abnormal temperature is designated as the abnormal photovoltaic junction box.

[0045] On the other hand, if there are no abnormal temperatures in the temperature data set, it means that the photovoltaic junction box is working normally and there is no need to perform subsequent shutdown actions. Repeat the above steps S101 to S103.

[0046] Step S105: Close the bus branch where the abnormal photovoltaic junction box is located.

[0047] A combiner branch refers to a DC circuit that connects the photovoltaic module in series to the input terminal of the combiner box.

[0048] For example, junction box No. 5 is located in the second bus branch. When junction box No. 5 is determined to be an abnormal photovoltaic junction box, a trip command is sent to the DC switch of the second bus branch to cut off the electrical connection of the bus branch.

[0049] By adopting the above technical solution, the temperature data of each junction box terminal is used as the monitoring object. After calculating the reference temperature, it is compared one by one. Junction boxes with temperature deviations exceeding the preset threshold are identified as abnormal and their corresponding branches are shut down. This method realizes automated closed-loop monitoring and fault isolation of the photovoltaic system's operating thermal state. It can promptly cut off the circuit when abnormal temperature rise occurs in the junction box, effectively preventing the escalation of faults and fire hazards, and improving the operational safety of the photovoltaic system.

[0050] In real-world scenarios, the external environment can also affect the temperature of photovoltaic junction boxes, and simply using statistical values ​​from temperature data sets as a reference temperature can easily lead to inaccuracies. Therefore, this application discloses a method for calculating a reference temperature. (Refer to...) Figure 2 The method includes: Step S201: Collect the ambient temperature of the photovoltaic system.

[0051] Ambient temperature refers to the atmospheric temperature of the area where the photovoltaic system is located. Optionally, temperature sensors are installed within the photovoltaic system's premises, and the data collected by these sensors is the ambient temperature.

[0052] Step S202: Obtain the location and environmental information of the photovoltaic system.

[0053] Location information refers to data indicating the geographical installation location of the photovoltaic system. Optionally, location information includes, but is not limited to, latitude and longitude, and altitude.

[0054] Environmental information refers to data indicating the current environmental status of the photovoltaic system. Optional environmental information includes, but is not limited to, cloud cover information and wind speed information.

[0055] Step S203: Adjust the ambient temperature based on the location information and environmental information to obtain the updated ambient temperature.

[0056] Ambient temperature alone cannot accurately reflect the actual thermal environment experienced by the junction box, as solar radiation generates additional heat, and wind cooling removes heat. Therefore, it is necessary to correct the ambient temperature using location and environmental information to obtain an updated ambient temperature. The specific calculation process will be detailed later. Figure 3 The embodiments shown are not elaborated here.

[0057] Step S204: Calculate the mean of the temperature data set to obtain the temperature mean.

[0058] The average temperature refers to the arithmetic mean of the temperature values ​​of all junction box terminals within the temperature data set.

[0059] Step S205: Calculate and update the ambient temperature and the average temperature using weighted averages to obtain the baseline temperature.

[0060] For example, let the updated ambient temperature be T1, and the average temperature be T2. Then the baseline temperature is α×T1+(1-α)×T2, where α is a weight value, and the value of α ranges from [0, 1]. Specifically, when the sample size of the temperature dataset is large and the data consistency is good, the value of α can be reduced to make the baseline temperature more dependent on the actual average temperature; conversely, when the sample size is small or the data fluctuates greatly, the value of α can be increased to make the baseline temperature more dependent on the environmental estimation results. Optionally, the value of α is 0.3.

[0061] By adopting the above technical solution, the determination of the reference temperature is based not only on the average temperature of each junction box, but also on the updated ambient temperature adjusted for location and environmental information, and the two are combined through a weighted average. This allows the reference temperature to comprehensively reflect the normal thermal state of the junction box under current operating conditions, avoiding misjudgments caused by relying solely on the average or ambient temperature, and improving the accuracy of abnormal temperature identification and adaptability to different installation environments.

[0062] This application discloses a method for calculating updated ambient temperature. (Refer to...) Figure 3 The method includes: Step S301: Obtain latitude and altitude data from the location information.

[0063] Latitude data refers to the degree of latitude of the photovoltaic system, while altitude data represents the vertical height of the photovoltaic system's location relative to mean sea level. Both latitude and altitude data can be derived from pre-stored power plant parameters.

[0064] Step S302: Calculate the solar altitude angle based on latitude data and the current date, and determine the solar radiation intensity factor based on the solar altitude angle.

[0065] The solar altitude angle refers to the angle between the sun's rays and the local ground plane. Specifically, let Lat be the latitude data and H be the solar altitude angle, then we have sin(H) = sin(Lat) × sin(δ) + cos(Lat) × cos(δ), where δ is the solar latitude, which is determined by the current date.

[0066] The solar radiation intensity factor reflects the solar radiation power received per unit area. Specifically, if the solar altitude angle is H, then the solar radiation power S = S0 × sin(H) × k, where S0 is the solar constant, approximately 1367 W / m², and k (with a value between 0.60 and 0.95) is an empirical value of atmospheric transmittance.

[0067] Step S303: Obtain the atmospheric pressure correction coefficient using altitude data, and correct the solar radiation intensity factor using the atmospheric pressure correction coefficient to obtain the corrected radiation factor.

[0068] Altitude affects atmospheric quality and atmospheric pressure. At high altitudes, the atmosphere is thinner, solar radiation has a shorter path to penetrate and attenuates less, which in turn affects the value of the solar radiation intensity factor.

[0069] Optionally, the correspondence between altitude data and atmospheric pressure correction coefficient can be pre-stored, and the corresponding data can be stored in memory for easy retrieval at any time.

[0070] Specifically, the corrected radiation factor is obtained by multiplying the atmospheric pressure correction factor by the solar radiation intensity factor.

[0071] Step S304: Obtain cloud cover information from the environmental information, determine the cloud attenuation coefficient based on the cloud cover information, and calculate the product of the corrected radiation factor and the cloud attenuation coefficient to obtain the effective radiation-induced temperature increment.

[0072] Cloud cover information describes the proportion of cloud cover in the sky and can be obtained through meteorological sensors or meteorological servers, such as cloud height meters.

[0073] The cloud attenuation coefficient is a coefficient that reflects the weakening effect of clouds on solar radiation. Specifically, the correspondence between cloud amount information and cloud attenuation coefficient is stored in advance, and the corresponding information is saved in memory for easy retrieval at any time.

[0074] Step S305: Obtain the wind speed from the environmental information and calculate the reduction in air-cooled temperature based on the wind speed.

[0075] Wind speed is part of the environmental information; the wind-cooling effect accelerates convective heat dissipation from the junction box surface, causing its temperature to drop below the ambient temperature. For example, if the wind speed is v, then the reduction in temperature due to wind cooling is... , where a and b are empirical constants. For example, take a = 0.8 and b = 0.6.

[0076] Step S306: Calculate the sum of ambient temperature, effective radiation-induced temperature increment, and air-cooled temperature decrease to obtain the updated ambient temperature.

[0077] By adopting the above technical solution, the adjustment of ambient temperature comprehensively takes into account the effects of multiple factors such as solar radiation, cloud cover attenuation, and wind cooling. Radiation intensity is calculated using latitude and altitude, and the radiation increment is corrected by combining cloud cover data. Wind speed is used to quantify wind cooling, making the updated ambient temperature closer to the actual perceived temperature of the photovoltaic junction box. This further improves the representativeness of the reference temperature and the reliability of subsequent anomaly detection.

[0078] In the following embodiments, some photovoltaic junction boxes may show normal temperature data at the current moment, but these junction boxes actually have potential hidden dangers. Therefore, this application discloses a method for troubleshooting potential faults in photovoltaic junction boxes. (Refer to...) Figure 4 The method includes: Step S401: Determine the remaining temperatures in the temperature data set, excluding abnormal temperatures.

[0079] For example, by removing outlier temperatures from the temperature dataset, the remaining data is the residual temperature referred to in this step.

[0080] Step S402: Determine the historical temperature data corresponding to the remaining temperature.

[0081] Historical temperature data refers to the temperature sequence that has been continuously collected and recorded within a time window prior to the current moment. For example, for each photovoltaic junction box in the remaining temperature range, its historical temperature data can be retrieved.

[0082] Step S403: Perform statistical processing on the historical temperature data to obtain standard historical temperature data.

[0083] In one implementation, for each junction box's historical temperature data, a sliding time window is used to extract window temperature data from the historical temperature data, and the average of the window temperature data is calculated. The position of the sliding time window is adjusted, and the aforementioned steps are repeated to obtain several averages. The average of the aforementioned several averages is calculated to obtain the standard historical temperature data.

[0084] In another implementation, the average value of historical temperature data is calculated to obtain standard historical temperature data.

[0085] Step S404: Plot the standard historical temperature data to obtain the standard historical temperature curve, and plot the historical temperature data to obtain the historical temperature curve.

[0086] The standard historical temperature curve is a smooth curve drawn from standard historical temperature data. It can reflect the typical trend of junction box temperature changes, while the historical temperature curve is a curve drawn from raw historical temperature data. It contains various fluctuation details of photovoltaic junction boxes in actual operation.

[0087] For example, a curve can be plotted with time on the x-axis and standard historical temperature data on the y-axis to form a standard historical temperature curve. Similarly, a curve can be plotted with time on the x-axis and historical temperature data on the y-axis to form a historical temperature curve.

[0088] Step S405: Calculate the similarity between the standard historical temperature curve and the historical temperature curve to obtain the first similarity.

[0089] For example, take the temperature values ​​of the standard historical temperature curve and the historical temperature curve at the same time point to obtain the temperature value combination, and calculate the linear correlation of the temperature value combination; repeat the above steps until the time on the horizontal axis is traversed to form a linear correlation set; calculate the mean of the linear correlation set to obtain the first similarity.

[0090] Step S406: Determine the target similarity that is less than the first similarity threshold in the first similarity.

[0091] The first similarity threshold is a boundary value used to distinguish whether a temperature change pattern significantly deviates from a standard pattern.

[0092] Step S407: The photovoltaic junction box corresponding to the target similarity is taken as the metastable photovoltaic junction box.

[0093] Metastable photovoltaic junction boxes refer to photovoltaic junction boxes that, although they have not triggered the abnormal temperature threshold, have a significantly lower similarity between their historical temperature evolution curve and the standard curve, indicating that their thermal state is in an abnormal evolution trend and that they have potential deterioration risks.

[0094] Step S408: Close the bus branch where the metastable photovoltaic junction box is located.

[0095] By employing the above technical solution, after excluding identified abnormal temperatures, the historical trends of the remaining temperature data are further analyzed. By comparing the similarity between the actual historical temperature curve and the standard historical temperature curve, metastable junction boxes whose temperature evolution patterns deviate from the normal are identified and shut down. This method can proactively detect potential faults that are still in the development stage, have not yet triggered the temperature threshold, but have already shown a deteriorating trend, achieving an upgrade from passive alarm to proactive early warning.

[0096] When identifying metastable photovoltaic (PV) junction boxes, it's important to note that some junction boxes may exhibit delays in temperature data generation and transmission due to aging transmission lines. These junction boxes may be functioning normally, but the delays in temperature data generation and transmission can lead to them being mistakenly identified as metastable. This application discloses a method for verifying metastable PV junction boxes. (Refer to...) Figure 5 The method includes: Step S501: Use the historical temperature curve corresponding to the target similarity as the candidate historical temperature curve.

[0097] Candidate historical temperature curves refer to historical temperature curves with a first similarity below the threshold.

[0098] Step S502: Perform the selection step, which includes selecting the i-th candidate historical temperature curve from the candidate historical temperature curves, where i is an integer with an initial value of 1.

[0099] The selection step is the starting point of the iterative processing. Optionally, a counter i can be set with an initial value of 1. Specifically, during the selection step, a candidate curve is selected from the set of candidate historical temperature curves by index i as the current processing object.

[0100] Step S503: Execute the negative delay step. The negative delay step performs negative delay processing on the i-th candidate historical temperature curve according to the j-th delay length to obtain the updated historical temperature curve, where j is an integer with an initial value of 1.

[0101] Negative time delay processing refers to shifting the candidate historical temperature curve to the left (i.e., to an earlier time direction) by a time delay to explore whether the temperature change of the candidate historical temperature curve is ahead or behind in time.

[0102] If the time range of the shifted curve will have partial overlap and partial gaps, the gaps can be truncated, meaning only the portion that overlaps with the standard historical temperature curve after shifting can be retained for comparison.

[0103] It should be noted that the value of j needs to be reset every time i is updated.

[0104] Step S504: Perform the calculation step, which includes calculating the similarity between the standard historical temperature curve and the updated temperature curve to obtain the second similarity.

[0105] The second similarity refers to the quantitative value of the similarity between the updated historical temperature curve and the standard historical temperature curve. Its calculation method can be referred to the first similarity, and will not be repeated here.

[0106] Step S505: If the second similarity is greater than or equal to the second similarity threshold, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is used as the substitute photovoltaic junction box.

[0107] The second similarity threshold can be equal to or less than the first similarity threshold.

[0108] When the second similarity score is greater than or equal to the second similarity threshold, it indicates that after a certain time delay adjustment, the similarity between the updated curve and the standard curve has reached a high level, and the temperature change pattern of the junction box matches the standard historical temperature curve after time phase correction. This means that its previous low similarity score was mainly caused by time offset, not by inherent degradation, and therefore it is classified as a replacement photovoltaic junction box.

[0109] Step S506: Update i to i+1 and return to execute the selection step.

[0110] After completing the evaluation of all candidate junction boxes for the i-th candidate junction box, this step increments the index i to i+1, and the process returns to the selection step (i.e., step S502) to continue performing the same analysis process on the next candidate historical temperature curve.

[0111] Step S507: If the second similarity is less than the second similarity threshold, then determine whether the j-th time extension is greater than the time extension threshold.

[0112] The time delay threshold is the maximum allowed negative time delay steps or duration. If this limit is exceeded, even if the similarity still does not meet the standard, it is confirmed that there is an essential abnormality in the photovoltaic junction box, in order to prevent the omission of real faults due to insufficient time delay.

[0113] When the second similarity is less than the second similarity threshold, the similarity between the updated curve and the standard curve is still not at an acceptable level at the current time extension. The temperature change pattern of the photovoltaic junction box still deviates significantly from the standard pattern even after time axis shift. In this case, it is not directly classified as metastable, but rather other time extensions are further assessed to determine their suitability.

[0114] Step S508: If yes, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is taken as the metastable photovoltaic junction box.

[0115] When the j-th time extension exceeds the time extension threshold, it means that within all reasonable time extension ranges, the similarity between the candidate historical temperature curve and the standard historical temperature curve consistently fails to reach the second similarity threshold. This fully demonstrates that the temperature change pattern of the photovoltaic junction box exhibits a fundamental distortion, rather than a simple time phase shift, constituting a substantial degradation characteristic. Therefore, this step classifies it as a metastable photovoltaic junction box.

[0116] Step S509: If not, update j to j+1 and repeat the negative delay step and calculation step.

[0117] By adopting the above technical solution, negative time delay analysis is introduced into the process of identifying metastable junction boxes. By progressively adjusting the time offset of historical temperature curves, their similarity to the standard curve is recalculated. If the similarity meets the requirements at a certain time delay, it is classified as a substitute junction box. This method can identify potential faults where time deviations occur in abnormal temperature patterns, refines the judgment logic for metastable states, and reduces false shutdowns.

[0118] This application discloses a predictive processing method for replacement photovoltaic junction boxes. (Refer to...) Figure 6 The method includes: Step S601: Record the temperature data corresponding to the substitute photovoltaic junction box as the substitute temperature data.

[0119] Step S602: Set the historical time period according to the current time.

[0120] A historical time period is a time interval extending backward from the current time to a predetermined length. Historical time periods can be used to limit the data selection range for temperature trend analysis. For example, if the current time is 14:00, then the historical time period is from 12:00 to 14:00.

[0121] Step S603: Determine the historical substitute temperature corresponding to the historical time period from the substitute temperature data, and determine the current substitute temperature corresponding to the current moment from the substitute temperature data.

[0122] Historical backup temperature refers to the sequence of temperature monitoring values ​​in the backup temperature data that fall within a set historical time period, while current backup temperature refers to the temperature monitoring value in the backup temperature data corresponding to the current moment.

[0123] Step S604: Calculate the slope of each time period within the historical period based on the historical substitute temperature.

[0124] For example, the historical time period is divided into N consecutive sub-time periods. For each sub-time period, the slope is calculated based on the historical replacement temperature.

[0125] Step S605: Take the maximum value of the slope to obtain the maximum slope.

[0126] The maximum slope refers to the maximum value of the slope among all sub-periods within the historical period, which reflects the fastest rate of temperature increase of the substitute photovoltaic junction box in the recent historical period.

[0127] Step S606: Calculate the future predicted temperature based on the maximum slope, the j-th time extension, and the current substitute temperature.

[0128] The predicted future temperature is the expected temperature value after one time delay period, which is obtained by extrapolating the recent maximum warming rate, the time delay, and the current temperature. For example, if the maximum slope is k, the j-th time delay is t, and the current substitute temperature is T, then the predicted future temperature is T+kt.

[0129] Step S607: If the difference between the predicted temperature and the reference temperature is greater than the preset temperature difference, then shut down the combiner branch where the backup photovoltaic junction box is located.

[0130] If the difference between the predicted temperature and the reference temperature is greater than the preset temperature difference, it is determined that the backup photovoltaic junction box is very likely to exceed the temperature limit in the near future, and the risk of failure is imminent. Therefore, shutdown measures are taken in advance to shut down the combiner branch where the backup photovoltaic junction box is located.

[0131] By employing the above technical solution, for backup junction boxes that have not yet triggered shutdown conditions, the maximum slope for each time period is calculated using their historical temperature data, and the future temperature is predicted by combining the time extension and the current temperature. If the predicted temperature will exceed the allowable range, the branch circuit containing that box is shut down in advance. This method achieves a proactive response to impending faults, taking protective measures before the fault actually occurs, further enhancing the system's active safety protection capabilities.

[0132] This application discloses a method for observing and processing a replacement photovoltaic junction box. (Refer to...) Figure 7 The method includes: Step S701: If the difference between the predicted future temperature and the reference temperature is less than or equal to the preset temperature difference, then mark the substitute photovoltaic junction box as the observation photovoltaic junction box.

[0133] If the difference between the predicted future temperature and the reference temperature is less than or equal to the preset temperature difference, it indicates that even extrapolating according to the recent maximum temperature rise rate, the expected temperature of the backup photovoltaic junction box after one time delay period is still within the acceptable safe range. Therefore, there is no need to take immediate shutdown measures. However, given that it has been identified as a backup state with time phase shift, it cannot be directly regarded as completely normal, and is therefore marked as an observation photovoltaic junction box.

[0134] Step S702: Obtain continuous temperature data of the photovoltaic junction box during the preset observation period to form an observation temperature sequence.

[0135] The preset observation period is a short-term time window for intensive temperature monitoring of the photovoltaic junction box.

[0136] For example, the preset observation period is 15 minutes backward from the current time to 5 minutes after the current time, for a total of 20 minutes. Alternatively, the preset observation period is 20 minutes backward from the current time to the current time.

[0137] Step S703: Perform a second-order difference operation on the observed temperature sequence to obtain the temperature change acceleration sequence.

[0138] Second-order difference operation refers to performing two consecutive first-order difference operations on a sequence, which can extract the acceleration information of temperature change, that is, the rate of change of temperature, and can reveal whether the temperature is accelerating upward or accelerating downward.

[0139] Step S704: Extract the maximum acceleration value from the temperature change acceleration sequence.

[0140] The maximum acceleration value refers to the acceleration with the largest value in the temperature change acceleration sequence.

[0141] Step S705: If the maximum acceleration value is greater than the preset acceleration threshold, the observed photovoltaic junction box will be identified as an abnormal photovoltaic junction box, and the bus branch in which it is located will be shut down.

[0142] If the maximum acceleration value is greater than the preset acceleration threshold, it indicates that the temperature of the observed photovoltaic junction box is not only rising, but the rate of increase is also accelerating, presenting a dangerous situation of accelerated heating. This nonlinear accelerated heating is usually a sign of serious faults such as a sharp increase in contact resistance, local thermal runaway, or sudden deterioration of heat dissipation conditions. Therefore, the observed photovoltaic junction box needs to be identified as an abnormal photovoltaic junction box, and its bus branch needs to be shut down to ensure safety.

[0143] Step S706: If the maximum acceleration value is less than or equal to the preset acceleration threshold, the observed photovoltaic junction box will be redefined as a metastable photovoltaic junction box, and the negative time delay step and calculation step will be executed.

[0144] If the maximum acceleration value is less than or equal to the preset acceleration threshold, it indicates that the temperature change of the observed photovoltaic junction box is generally stable during the observation period, and there are no obvious signs of accelerated deterioration. Its previous temperature pattern deviation may have been caused only by environmental disturbances or normal operating condition changes. Therefore, this observed photovoltaic junction box is identified as a metastable photovoltaic junction box, and it will continue to undergo time-delay analysis and trend assessment in subsequent monitoring cycles along with other metastable junction boxes.

[0145] By employing the above technical solution, backup junction boxes whose predicted temperatures do not exceed the limit are marked as observation targets. The maximum acceleration value of temperature change is extracted by analyzing the second-order difference of temperature changes within a preset observation period. If the acceleration exceeds the threshold, it indicates a rapid deterioration of the temperature, and the system is immediately upgraded to an anomaly and its branch is shut down. Conversely, it reverts to a metastable state for continued monitoring. This dynamic evaluation mechanism effectively prevents the risk of sudden temperature changes, balancing safety and the system's continuous operation capability.

[0146] Based on the same inventive concept, this application provides a monitoring system for a photovoltaic system. Please refer to... Figure 8 ,include: Module 801 is used to acquire temperature data; The memory 802 is used to store the program for the monitoring method of the photovoltaic system described above; The processor 803 can load and execute programs in memory to implement the aforementioned photovoltaic system monitoring method.

[0147] By adopting the above technical solution, the temperature data of each junction box terminal is used as the monitoring object. After calculating the reference temperature, it is compared one by one. Junction boxes with temperature deviations exceeding the preset threshold are identified as abnormal and their corresponding branches are shut down. This method realizes automated closed-loop monitoring and fault isolation of the photovoltaic system's operating thermal state. It can promptly cut off the circuit when abnormal temperature rise occurs in the junction box, effectively preventing the escalation of faults and fire hazards, and improving the operational safety of the photovoltaic system.

[0148] 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.

[0149] This application provides a computer-readable storage medium storing a computer program that can be loaded by a processor and executed as a monitoring method for a photovoltaic system.

[0150] 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.

[0151] 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 by the processor and executed to monitor a photovoltaic system.

[0152] 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.

[0153] 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 monitoring method for a photovoltaic system, characterized in that, include: Temperature data of each photovoltaic junction box is collected to form a temperature data set, wherein the temperature data originates from the wiring terminals of the photovoltaic junction box; Calculate the reference temperature based on the temperature data set; Based on the reference temperature, determine whether there is an abnormal temperature in the temperature data set, wherein the difference between the abnormal temperature and the reference temperature is greater than a preset temperature difference. If it exists, the photovoltaic junction box corresponding to the abnormal temperature will be regarded as the abnormal photovoltaic junction box; Shut down the bus branch where the abnormal photovoltaic junction box is located.

2. The monitoring method for a photovoltaic system according to claim 1, characterized in that, The calculation of the reference temperature based on the temperature data set includes: Collect the ambient temperature of the photovoltaic system; Obtain the location and environmental information of the photovoltaic system; Based on the location information and the environmental information, the ambient temperature is adjusted to obtain an updated ambient temperature; Calculate the mean of the temperature data set to obtain the average temperature. The updated ambient temperature and the average temperature are weighted and calculated to obtain the reference temperature.

3. The monitoring method for a photovoltaic system according to claim 2, characterized in that, The step of adjusting the ambient temperature based on the location information and the environmental information to obtain an updated ambient temperature includes: Obtain the latitude and altitude data from the location information; Based on the latitude data and the current date, calculate the solar altitude angle, and determine the solar radiation intensity factor based on the solar altitude angle; The atmospheric pressure correction coefficient is obtained using the altitude data, and the solar radiation intensity factor is corrected using the atmospheric pressure correction coefficient to obtain the corrected radiation factor; Obtain cloud cover information from the environmental information, determine the cloud attenuation coefficient based on the cloud cover information, and calculate the product of the corrected radiation factor and the cloud attenuation coefficient to obtain the effective radiation-induced temperature increment. Obtain the wind speed from the environmental information, and calculate the reduction in air-cooled temperature based on the wind speed; The updated ambient temperature is obtained by summing the ambient temperature, the effective radiation-induced temperature increment, and the air-cooled temperature reduction.

4. The monitoring method for a photovoltaic system according to claim 1, characterized in that, The method further includes: Determine the remaining temperatures in the temperature data set, excluding the abnormal temperatures; Determine the historical temperature data corresponding to the remaining temperature; The historical temperature data were statistically processed to obtain standard historical temperature data; The standard historical temperature data is processed to obtain a standard historical temperature curve, and the historical temperature data is processed to obtain a historical temperature curve. Calculate the similarity between the standard historical temperature curve and the historical temperature curve to obtain the first similarity. Determine target similarities that are less than the first similarity threshold from the first similarity; The photovoltaic junction box corresponding to the target similarity is regarded as the metastable photovoltaic junction box; Shut down the bus branch where the metastable photovoltaic junction box is located.

5. The monitoring method for a photovoltaic system according to claim 4, characterized in that, The step of using the photovoltaic junction box corresponding to the target similarity as a metastable photovoltaic junction box includes: The historical temperature curves corresponding to the target similarity are used as candidate historical temperature curves; The selection step includes selecting the i-th candidate historical temperature curve from the candidate historical temperature curves, where i is an integer with an initial value of 1. A negative delay step is performed, wherein the negative delay step performs negative delay processing on the i-th candidate historical temperature curve according to the j-th delay length to obtain an updated historical temperature curve, where j is an integer with an initial value of 1; The calculation step includes calculating the similarity between the standard historical temperature curve and the updated temperature curve to obtain a second similarity. If the second similarity is greater than or equal to the second similarity threshold, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is used as a substitute photovoltaic junction box; i is updated to i+1, and the selection step is returned to be executed. If the second similarity is less than the second similarity threshold, then determine whether the j-th time extension is greater than the time extension threshold; If so, then the photovoltaic junction box corresponding to the i-th candidate historical temperature curve is taken as the metastable photovoltaic junction box; i is updated to i+1, and the selection step is returned to be executed; If not, update j to j+1 and repeat the negative delay step and the calculation step.

6. The monitoring method for a photovoltaic system according to claim 5, characterized in that, The method further includes: Record the temperature data corresponding to the substitute photovoltaic junction box as the substitute temperature data; Set the historical time period based on the current time; The historical substitute temperature corresponding to the historical time period is determined from the substitute temperature data, and the current substitute temperature corresponding to the current moment is determined from the substitute temperature data. Calculate the slope of each time period within the historical period based on the historical replacement temperature; The maximum slope is obtained by taking the maximum value among the slopes. Calculate the future predicted temperature based on the maximum slope, the j-th time extension, and the current substitute temperature; If the difference between the predicted future temperature and the reference temperature is greater than the preset temperature difference, then the bus branch where the substitute photovoltaic junction box is located is shut down.

7. The monitoring method for a photovoltaic system according to claim 6, characterized in that, The method further includes: If the difference between the predicted future temperature and the reference temperature is less than or equal to the preset temperature difference, then the substitute photovoltaic junction box is marked as an observation photovoltaic junction box. The continuous temperature data of the photovoltaic junction box during the preset observation period are obtained to form an observation temperature sequence; Perform a second-order difference operation on the observed temperature sequence to obtain a temperature change acceleration sequence; Extract the maximum acceleration value from the temperature change acceleration sequence; If the maximum acceleration value is greater than the preset acceleration threshold, the observed photovoltaic junction box is determined to be an abnormal photovoltaic junction box, and the bus branch in which it is located is shut down; If the maximum acceleration value is less than or equal to the preset acceleration threshold, the observed photovoltaic junction box is redefined as the metastable photovoltaic junction box, and the execution of the negative time delay step and the calculation step is returned.

8. A monitoring system for a photovoltaic system, characterized in that, The system is used to perform the monitoring method for a photovoltaic system as described in any one of claims 1 to 7, including: The acquisition module is used to acquire temperature data; A memory for storing the program of the monitoring method for the photovoltaic system; The processor and the program in the memory can be loaded and executed by the processor to implement the monitoring method of the photovoltaic system.

9. A smart terminal, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer program is stored that can be loaded by a processor and execute the method as described in any one of claims 1 to 7.

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