Methods for monitoring the terminal contact status of photovoltaic inverters and related products

Abstract

This invention relates to a method for monitoring the contact status of photovoltaic inverter terminals and related products. The method includes: acquiring voltage and current signals of a target terminal during photovoltaic inverter operation, and calculating the dynamic contact resistance of the target terminal based on the voltage and current signals. Then, a measured characteristic quantity is extracted from the dynamic contact resistance to obtain a standard characteristic quantity of the target terminal under reliable conductivity. Finally, the measured characteristic quantity is compared with the standard characteristic quantity to obtain the contact status of the target terminal. This invention improves the accuracy of monitoring the contact status of photovoltaic inverter target terminals by acquiring voltage and current signals of the target terminal, calculating the dynamic contact resistance, extracting measured characteristic quantities, and comparing them with standard characteristic quantities under normal conductivity to obtain the contact status of the target terminal. This invention ensures the safe and stable operation of the photovoltaic power generation system.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a method for monitoring the terminal contact status of a photovoltaic inverter and related products. Background Technology

[0002] In the field of photovoltaic power generation technology, photovoltaic inverters, as the core power conversion equipment of photovoltaic power generation systems, are subjected to high current, temperature and humidity changes, vibration, and oxidation corrosion on their terminals over long periods of time, making them prone to problems such as loosening, aging, and poor contact. Abnormal terminal contact can lead to increased contact resistance and localized heating, and in severe cases, sparking and burning, causing inverter malfunctions and shutdowns, or even electrical safety accidents, posing a serious threat to the safe and stable operation of photovoltaic power generation systems.

[0003] Currently, in the field of photovoltaic power generation technology, the monitoring of inverter terminal contact status mostly adopts a basic single resistance threshold judgment method. This typically relies solely on whether the steady-state contact resistance value exceeds a fixed threshold to generate a simple over-limit alarm, resulting in a relatively limited overall monitoring and diagnostic scope. This method can only roughly identify faults with continuously abnormally high resistance, and is highly prone to false alarms or missed alarms. Summary of the Invention

[0004] One object of the present invention is to overcome at least one deficiency in the prior art and to provide a method for monitoring the terminal contact status of a photovoltaic inverter and related products thereof.

[0005] A further objective of this invention is to optimize the monitoring method for the contact status of photovoltaic inverter terminals, thereby improving the accuracy of identifying the contact status of photovoltaic inverter terminals.

[0006] Specifically, the present invention provides a method for monitoring the terminal contact status of a photovoltaic inverter, comprising: Acquire the voltage and current signals of the target terminals during the operation of the photovoltaic inverter; Calculate the dynamic contact resistance of the target terminal based on the voltage and current signals; The measurement characteristic quantities are extracted from the dynamic contact resistance; these measurement characteristic quantities are used to characterize the conductivity state of the target terminal. Obtain the standard characteristic quantities of the target terminal under a reliable conductive state; The contact state of the target terminal is obtained by comparing the measured characteristic quantity with the standard characteristic quantity.

[0007] Optionally, the measured characteristic quantities include: steady-state resistance value, resistance change rate, and voltage distortion characteristic value at the current zero-crossing point; Standard characteristic quantities include: standard resistance value of conduction, standard resistance change rate, and standard voltage distortion value at the current zero crossing point; The steps for comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal include: Determine whether the difference between the steady-state resistance value and the conductive standard resistance value is less than a preset difference threshold; If the difference between the steady-state resistance value and the standard resistance value is less than a preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is less than a preset first conversion rate threshold. If the difference between the resistance change rate and the standard resistance change rate is less than the first conversion rate threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than the preset distortion threshold. If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than the preset distortion threshold, the contact state is determined to be normal.

[0008] Optionally, the step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal further includes: If the difference between the rate of change of resistance and the standard rate of change of resistance is greater than or equal to the first conversion rate threshold, the contact condition is determined to be slightly loose or aged. If the difference between the steady-state resistance value and the standard resistance value is greater than or equal to a preset difference threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than a preset distortion threshold. If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is greater than or equal to the preset distortion threshold, the contact condition is determined to be a severely loose condition. If the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to a preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is greater than a preset second conversion rate threshold. If the difference between the rate of change of resistance and the standard rate of change of resistance is greater than the second conversion rate threshold, the contact state is determined to be an overheating risk state.

[0009] Optionally, after obtaining the contact state of the target terminal, the method further includes: Based on the contact status, corresponding graded protection actions are executed; among them... If the contact condition is slightly loose or aged, record the abnormal information and output the operation and maintenance inspection alarm. If the contact is severely loose, reduce the input power of the photovoltaic inverter; If the contact condition is at risk of overheating, disconnect the branch in the photovoltaic inverter corresponding to the target terminal.

[0010] Optionally, before the step of calculating the dynamic contact resistance of the target terminal based on the voltage and current signals, the method further includes: Determine whether the current signal is greater than a preset current threshold. If so, perform the operation of calculating the dynamic contact resistance of the target terminal based on the voltage and current signals.

[0011] Optionally, after obtaining the contact state of the target terminal, the method further includes: Acquire ambient temperature data of the target terminal, real-time power data of the photovoltaic inverter, and historical operating data of the target terminal; The contact status is corrected based on contact status and ambient temperature data, real-time power data, and historical operating data; among which... Ambient temperature data is used to distinguish the causes of dynamic contact resistance increase and to determine whether the cause is due to changes in ambient temperature or loosening of the target terminal. Real-time power data is used to analyze the characteristics of dynamic contact resistance as a function of load. Historical operating data is used to analyze the changing trend of dynamic contact resistance.

[0012] Optionally, after the step of acquiring the voltage and current signals of the target terminal during the operation of the photovoltaic inverter, the method further includes: Determine whether the amplitude of the voltage signal change is greater than a preset voltage change threshold, or whether the amplitude of the current signal change is greater than a preset current change threshold. If so, start the acquisition mode and acquire the waveforms of the voltage signal and the current signal within a preset time before and after the trigger time; Identify resistance spikes and voltage glitches based on the waveforms of the voltage and current signals. The contact state is corrected based on resistance spikes and voltage glitches.

[0013] The present invention provides a method for monitoring the contact status of photovoltaic inverter terminals. First, it acquires the voltage and current signals of the target terminal during photovoltaic inverter operation and calculates the dynamic contact resistance of the target terminal based on these signals. Then, it extracts a measured characteristic quantity from the dynamic contact resistance to obtain the standard characteristic quantity of the target terminal under reliable conductivity. Finally, it compares the measured characteristic quantity with the standard characteristic quantity to obtain the contact status of the target terminal. This invention achieves contact status diagnosis by acquiring the voltage and current signals of the target terminal, calculating the dynamic contact resistance, extracting measured characteristic quantities, and comparing them with the standard characteristic quantity under normal conductivity. Compared to traditional single-threshold discrimination methods, this invention can distinguish between normal operating condition fluctuations and contact anomalies, improving the accuracy and reliability of photovoltaic inverter terminal contact status monitoring to ensure the safe and stable operation of the photovoltaic power generation system.

[0014] Furthermore, based on the fact that the resistance change rate is within the normal range, this invention further determines whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the corresponding standard value is less than a preset distortion threshold. This can effectively detect nonlinear conductivity anomalies caused by oxide layers or contaminants at the contact interface. Such nonlinear conductivity anomalies cannot be identified solely by the steady-state resistance value and the resistance change rate, thus filling the monitoring blind spot of traditional monitoring methods and significantly improving the detection rate of early contact defects.

[0015] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0016] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a flowchart illustrating a method for monitoring the terminal contact status of a photovoltaic inverter according to an embodiment of the present invention. Figure 2 This is a schematic flowchart illustrating the process of comparing a measured feature quantity with a standard feature quantity to obtain the contact state of a target terminal according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating the process of comparing a measured feature quantity with a standard feature quantity to obtain the contact state of a target terminal according to another embodiment of the present invention. Figure 4 This is a flowchart illustrating the process of comparing a measured feature quantity with a standard feature quantity to obtain the contact state of a target terminal according to another embodiment of the present invention. Figure 5 This is a flowchart illustrating the steps prior to the calculation of the dynamic contact resistance of the target terminal based on voltage and current signals according to an embodiment of the present invention. Figure 6 This is a flowchart illustrating the process after obtaining the contact state of the target terminal according to an embodiment of the present invention. Figure 7 This is a flowchart illustrating the process after the step of acquiring the voltage and current signals of the target terminal during the operation of a photovoltaic inverter, according to an embodiment of the present invention. Figure 8 This is a voltage and current characteristic curve of a target terminal under different contact states according to an embodiment of the present invention; Figure 9 This is a characteristic curve of the resistance and current of the target terminal under different operating conditions according to an embodiment of the present invention; Figure 10 This is a schematic diagram of a computer program product according to an embodiment of the present invention; Figure 11 This is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention; and Figure 12 This is a schematic diagram of a computer device according to an embodiment of the present invention. Detailed Implementation

[0017] Those skilled in the art should understand that the embodiments described below are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. These partial embodiments are intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present invention.

[0018] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein can be considered as a ordered list of executable instructions for implementing logical functions, which can be specifically implemented in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-based system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0019] This invention provides a method for monitoring the terminal contact status of a photovoltaic inverter, such as... Figure 1 As shown, the method for monitoring the terminal contact status of the photovoltaic inverter includes at least the following steps S101 to S105.

[0020] Step S101: Acquire the voltage and current signals of the target terminals during the operation of the photovoltaic inverter. This step obtains an electrical data source reflecting the terminal contact status by collecting the voltage signals across the target terminals and the current signals flowing through the terminals. This step enables monitoring of the terminal operating status without requiring shutdown or additional dedicated testing equipment, and does not affect the normal operation of the photovoltaic inverter.

[0021] Step S102: Calculate the dynamic contact resistance of the target terminal based on the voltage and current signals. This step calculates the dynamic contact resistance in real time based on Ohm's law, which can characterize the changes in conductivity at the terminal contact interface. Compared to traditional offline static resistance measurement methods, the dynamic contact resistance calculated in this step can reflect the real-time changes in contact resistance caused by factors such as load fluctuations, ambient temperature changes, or mechanical vibrations during the operation of the photovoltaic inverter.

[0022] Step S103: Extract measurement characteristic quantities from the dynamic contact resistance; these measurement characteristic quantities are used to characterize the conductivity state of the target terminal. This step, by extracting measurement characteristic quantities from the dynamic contact resistance to characterize the conductivity state of the target terminal, transforms the continuously changing dynamic contact resistance into a comparable state index, thereby characterizing the conductivity state of the target terminal and providing an analytical object for subsequent comparison and judgment with standard characteristic quantities.

[0023] Step S104: Obtain the standard characteristic quantities of the target terminal under reliable conductivity. This step obtains the standard characteristic quantities of the target terminal under reliable conductivity to obtain benchmark reference data for the normal contact state of the target terminal, providing a basis for subsequent feature comparison and establishing a standard to distinguish between normal and abnormal conductivity states.

[0024] In some optional embodiments, a reliable conductivity state refers to an ideal contact state in which the target terminal can transmit current stably and safely for a long period of time within its design rated operating range, without abnormal heating, excessive voltage drop, or nonlinear conductivity phenomena. A target terminal in a reliable conductivity state has sufficient and uniform contact pressure at its contact interface, free from defects such as looseness, excessive oxide layer, or contaminant accumulation. The contact resistance value is within the minimum allowable range and remains stable without significant fluctuations. Voltage and current exhibit a good linear ohmic relationship, with no significant nonlinear distortion near the current zero-crossing point. During continuous operation at rated current, the terminal temperature rise does not exceed the limits specified in national standards.

[0025] Step S105: Compare the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal. This step, by quantifying and comparing the measured characteristic quantity with the standard characteristic quantity, can directly identify the difference between the measured characteristic quantity and the standard characteristic quantity, thereby determining the current contact state of the target terminal.

[0026] In some optional embodiments, the measured characteristic quantities include: steady-state resistance value, rate of change of resistance, and voltage distortion characteristic value at the current zero-crossing point. Standard characteristic quantities include: standard conductive resistance value, standard rate of change of resistance, and standard voltage distortion characteristic value at the current zero-crossing point. For example... Figure 2 As shown, the step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal includes at least the following steps S201 to S204.

[0027] Step S201: Determine whether the difference between the steady-state resistance value and the conductive standard resistance value is less than a preset difference threshold. This step, by determining whether the difference between the steady-state resistance value and the conductive standard resistance value is less than the preset difference threshold, can filter out operating conditions with significantly abnormal steady-state resistance, reduce unnecessary subsequent feature comparison calculations, and improve diagnostic processing efficiency.

[0028] Step S202: If the difference between the steady-state resistance value and the standard resistance value is less than a preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is less than a preset first change rate threshold. This step, based on a normal steady-state resistance, further determines whether the difference between the resistance change rate and the standard resistance change rate is less than the preset first change rate threshold, which can identify early anomalies where the steady-state resistance has not yet exceeded the limit but has shown a slow deterioration trend.

[0029] Step S203: If the difference between the resistance change rate and the standard resistance change rate is less than the first conversion rate threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the standard voltage distortion value at the current zero-crossing point is less than a preset distortion threshold. This step, based on the resistance change rate being within the normal range, further determines whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the corresponding standard value is less than the preset distortion threshold. This can effectively detect nonlinear conductivity anomalies caused by oxide layers or contaminants at the contact interface. Such nonlinear conductivity anomalies cannot be identified solely by the steady-state resistance value and the resistance change rate, thus filling the monitoring blind spot of traditional monitoring methods and significantly improving the detection rate of early contact defects.

[0030] Step S204: If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than a preset distortion threshold, the contact state is determined to be normal. This step only determines the state to be normal when all three measured characteristic quantities in steps S201 to S203 meet the normal conditions. This can reduce the probability of misjudging when a single characteristic quantity is normal but there is actually a contact hazard, and improve the reliability of the normal state diagnosis result.

[0031] In some alternative embodiments, such as Figure 3 As shown, the step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal further includes at least the following steps S301 to S303.

[0032] Step S301: If the difference between the resistance change rate and the standard resistance change rate is greater than or equal to the first change rate threshold, the contact condition is determined to be slightly loose or aged. This step, by determining that the contact condition is slightly loose or aged when the difference between the resistance change rate and the standard resistance change rate is greater than or equal to the first change rate threshold, can detect the slow deterioration trend of the terminal contact condition before the steady-state resistance value exceeds the normal range, providing a basis for taking preventive maintenance measures in advance.

[0033] Step S302: If the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to a preset difference threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than the preset distortion threshold. This step, by further determining the difference between the voltage distortion characteristic value at the current zero-crossing point and the corresponding standard value when the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to the preset difference threshold, avoids the risk of misjudging the fault based solely on a single measured characteristic value of the steady-state resistance, thus improving the accuracy of contact state classification.

[0034] Step S303: If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is greater than or equal to a preset distortion threshold, the contact state is determined to be severely loose. This step determines the contact state to be severely loose when the difference between the voltage distortion characteristic value at the current zero-crossing point and the corresponding standard value is greater than or equal to a preset distortion threshold. This step combines the abnormal state of steady-state resistance and voltage distortion, which can identify serious contact problems caused by oxide layers at the contact interface, insufficient contact pressure, etc., thereby effectively preventing serious accidents such as local overheating, arcing, burning, or even electrical fires caused by severe contact problems at the target terminals.

[0035] In some alternative embodiments, such as Figure 4 As shown, the step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal further includes at least the following steps S401 to S402.

[0036] Step S401: If the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to a preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is greater than a preset second conversion rate threshold. This step, when the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to the preset difference threshold, further determines whether the difference between the resistance change rate and the standard resistance change rate is greater than a preset second conversion rate threshold. This allows for a more detailed classification of abnormal steady-state resistance conditions, distinguishing between ordinary steady-state resistance increases and special abnormal states of rapid deterioration, thus improving the accuracy of photovoltaic inverter terminal contact status monitoring. Step S402: If the difference between the resistance change rate and the standard resistance change rate is greater than the second change rate threshold, the contact state is determined to be in an overheating risk state. This step, which determines the contact state to be in an overheating risk state when the difference between the resistance change rate and the standard resistance change rate is greater than the second change rate threshold, can issue an early warning before the terminal actually overheats and burns, effectively preventing terminal overheating and burnout accidents caused by rapid deterioration of contact resistance.

[0037] In some optional embodiments, the preset difference threshold can be set to 50% to 100% of the standard resistance value of the conductivity. For example, when the standard resistance value of the target terminal in a reliable conductivity state is 50 mΩ, the preset difference threshold can be set to 25 mΩ to 50 mΩ, preferably 30 mΩ. The first conversion rate threshold can be set to 1 mΩ to 5 mΩ per day, preferably 2 mΩ per day, to identify a slow deterioration trend in the contact state of the target terminal. The preset distortion threshold can be set to 0.5% to 2% of the inverter's rated voltage. For a three-phase photovoltaic inverter with a rated voltage of 380V, the preset distortion threshold can be set to 0.5V to 2V, preferably 1V. The second conversion rate threshold can be set to 5 mΩ to 20 mΩ per hour, preferably 10 mΩ per hour, to identify a further increase in resistance caused by contact resistance heating.

[0038] Those skilled in the art should understand that the above threshold is merely an illustrative example, and in practical applications, it can be reasonably adjusted according to different models of photovoltaic inverters, terminals of different materials, and different operating environment conditions to obtain the most accurate contact state.

[0039] In some optional embodiments, after obtaining the contact status of the target terminal, corresponding graded protection actions can be performed based on the contact status. Specifically, if the contact status is slightly loose or aged, abnormal information is recorded and an operation and maintenance inspection alarm is output. If the contact status is severely loose, the input power of the photovoltaic inverter is reduced. If the contact status is at risk of overheating, the branch in the photovoltaic inverter corresponding to the target terminal is disconnected.

[0040] This invention performs graded protection actions based on the contact status of the target terminals, minimizing unnecessary downtime losses while ensuring electrical safety and achieving an optimal balance between safety protection and power generation benefits. For minor loosening or aging, only abnormal information is recorded and maintenance alarms are output, without affecting the normal operation of the inverter. This avoids power generation losses due to over-protection and facilitates planned maintenance by maintenance personnel. For severe loosening, the inverter input power is proactively reduced to decrease the current flowing through the target terminals, thereby reducing contact surface heating, delaying fault deterioration, and maintaining partial power generation capacity, buying time for on-site maintenance. For overheating risk conditions, the faulty branch is disconnected instead of the entire unit is shut down, immediately isolating the fault point to eliminate safety hazards. This ensures continuous power generation from other normal branches, minimizing the impact of the fault on the system's power generation efficiency.

[0041] In some alternative embodiments, such as Figure 5 As shown, the step of calculating the dynamic contact resistance of the target terminal based on the voltage signal and the current signal includes at least the following steps S501 to S502.

[0042] Step S501: Determine whether the current signal is greater than a preset current threshold. This step, by pre-determining whether the current signal flowing through the target terminal is greater than a preset current threshold, can filter out the effective current range suitable for dynamic contact resistance calculation and eliminate invalid measurement data under low current conditions.

[0043] In some optional embodiments, the preset current threshold can be set to 5% to 15% of the rated current of the photovoltaic inverter, preferably 10% of the rated current. For example, for a photovoltaic inverter terminal with a rated current of 100A, the preset current threshold can be set to 5A to 15A, preferably 10A. For a photovoltaic inverter terminal with a rated current of 250A, the preset current threshold can be set to 12.5A to 37.5A, preferably 25A. For a photovoltaic inverter terminal with a rated current of 500A, the preset current threshold can be set to 25A to 75A, preferably 50A.

[0044] The reason for setting the above preset current threshold range is that when the current flowing through the terminal is less than 5% of the rated current, the relative error of the voltage measurement will be significantly amplified, causing the calculated dynamic contact resistance value to be distorted and unable to truly reflect the actual contact state of the terminal. However, when the current is higher than 15% of the rated current, the signal-to-noise ratio of the voltage measurement is high enough to ensure that the calculation accuracy of the dynamic contact resistance meets the diagnostic requirements.

[0045] Those skilled in the art should understand that the aforementioned preset current threshold is merely an illustrative example, and in practical applications, it can be reasonably adjusted according to the accuracy class of the voltage sensor, the rated current of the terminals, and the system's requirements for measurement accuracy. For example, when using a higher-precision voltage sensor, the preset current threshold can be appropriately reduced to expand the effective measurement range.

[0046] Step S502: When the current signal is greater than a preset current threshold, the dynamic contact resistance of the target terminal is calculated based on the voltage and current signals. This step, by only performing the dynamic contact resistance calculation when the current signal is greater than the preset current threshold, avoids the distortion in resistance calculation caused by amplified voltage measurement errors at low current levels, thus improving the accuracy of the dynamic contact resistance calculation. Simultaneously, by only performing the dynamic contact resistance calculation when the current signal is greater than the preset current threshold, the amount of invalid calculations performed by the system under low current conditions is reduced, improving the operating efficiency of the monitoring system.

[0047] In some alternative embodiments, such as Figure 6 As shown, after obtaining the contact state of the target terminal, the steps include at least steps S601 to S602.

[0048] Step S601 involves acquiring the ambient temperature data of the target terminal, the real-time power data of the photovoltaic inverter, and the historical operating data of the target terminal. The ambient temperature data is used to differentiate the causes of increased dynamic contact resistance, determining whether the cause is due to changes in ambient temperature or loosening of the target terminal. The real-time power data is used to analyze the characteristics of dynamic contact resistance changing with load. The historical operating data is used to analyze the trend of dynamic contact resistance changes. This step provides a reference for correcting the contact state by simultaneously acquiring the ambient temperature data of the target terminal, the real-time power data of the photovoltaic inverter, and the historical operating data of the target terminal. The ambient temperature data reflects the influence of the external environment on the terminal's conductivity, the real-time power data reflects the effect of load changes on contact resistance, and the historical operating data records the long-term evolution of the terminal's contact state. These three types of data complement each other, improving the accuracy of the contact state analysis.

[0049] Step S602: Correct the contact status based on contact status data, ambient temperature data, real-time power data, and historical operating data. This step, by combining ambient temperature data, real-time power data, and historical operating data to correct the contact status, can eliminate the influence of various interference factors on the diagnostic results, improving the accuracy and reliability of contact status identification. Specifically, ambient temperature data can be used to distinguish whether the increase in dynamic contact resistance is caused by normal ambient temperature changes or by poor terminal contact, avoiding misjudgments caused by temperature interference. Real-time power data can be used to analyze the characteristics of dynamic contact resistance changing with load, distinguishing between normal resistance fluctuations caused by load fluctuations and abnormal changes caused by contact faults. Historical operating data can be used to analyze the long-term trend of dynamic contact resistance, verifying the rationality of the current contact status by combining historical patterns, reducing the probability of missed judgments and false alarms.

[0050] In some alternative embodiments, such as Figure 7 As shown, after the step of acquiring the voltage and current signals of the target terminal during the operation of the photovoltaic inverter, at least the following steps S701 to S704 are included.

[0051] Step S701 determines whether the amplitude of the voltage signal fluctuation exceeds a preset voltage fluctuation threshold, or whether the amplitude of the current signal fluctuation exceeds a preset current fluctuation threshold. This step, by real-time monitoring of the amplitude fluctuations in the voltage and current signals and comparing them with the preset voltage or current fluctuation thresholds, can identify transient abnormal events in the electrical signals, providing triggering conditions for subsequent waveform acquisition. This step does not require continuous high-speed acquisition of all operating data; subsequent operations are only initiated when transient characteristics indicating a potential contact fault are detected. This effectively reduces system resource consumption and accurately captures early signals of transient faults.

[0052] Step S702: When the amplitude of the voltage signal change exceeds a preset voltage change threshold, or the amplitude of the current signal change exceeds a preset current change threshold, the acquisition mode is activated to acquire the waveforms of the voltage and current signals within a preset time period before and after the trigger moment. This step activates the acquisition mode when an electrical signal change is detected, acquiring complete voltage and current waveform data within a preset time period before and after the trigger moment. This not only completely records the entire process of transient anomalies, avoiding the omission of key fault information, but also avoids the burden of massive data storage and processing caused by continuous high-speed acquisition.

[0053] Step S703: Determine resistance spikes and voltage glitches based on the waveforms of the voltage and current signals. This step analyzes and processes the acquired transient voltage and current waveforms to extract the characteristics of resistance spikes and voltage glitches. These transient characteristics are the direct electrical manifestations of momentary disconnection, poor connection, or arcing at the terminal contact interface, and cannot be detected by conventional steady-state resistance and resistance change rate monitoring methods.

[0054] Step S704: Correct the contact state based on resistance spikes and voltage glitches. This step uses the extracted resistance spikes and voltage glitches to determine the contact state and make supplementary corrections. This can detect intermittent or sporadic contact failures that are difficult to identify using traditional methods.

[0055] In some alternative embodiments, such as Figure 8 As shown, the correspondence between contact states and electrical characteristics in this invention can be understood as follows: Curve 101 represents the VI characteristic curve when the target terminal is in a normal state. This curve exhibits good linear ohmic characteristics with a small slope, corresponding to a low contact resistance value of the target terminal (approximately 50 mΩ), which conforms to Ohm's law. Based on this, the present invention establishes standard characteristic quantities such as the standard conductivity resistance value and standard resistance change rate of the target terminal. Curve 102 represents the VI characteristic curve when the terminal is in a slightly loose or aged state. This curve still maintains a basic linear relationship, but the slope of the curve (corresponding to the contact resistance of the target terminal) increases overall, and the contact resistance value rises to approximately 150 mΩ. The present invention identifies this type of progressive contact fault by detecting anomalies in the steady-state resistance value and resistance change rate. Curve 103 represents the VI characteristic curve when the target terminal is in a severely loose state. This curve exhibits significant nonlinear distortion characteristics, especially in the region 104 near the current zero-crossing point. Due to the nonlinear conductivity caused by insufficient oxide layer at the contact interface or insufficient contact pressure, the voltage shows obvious "bulging" distortion. This type of distortion cannot be identified solely by steady-state resistance and resistance change rate indicators. This invention detects such serious contact defects by extracting the voltage distortion characteristic value at the current zero-crossing point. Region 104 is the voltage distortion characteristic region near the current zero-crossing point, which is the key feature extraction region used in this invention to distinguish severe looseness from other contact states.

[0056] In some alternative embodiments, such as Figure 9 As shown, the relationship between resistance and current at the target terminal of the photovoltaic inverter of this invention under different operating conditions can be understood as follows: Curve 301 represents the RI relationship curve under normal contact conditions of the terminals at room temperature, serving as a baseline reference for resistance characteristic analysis in this invention. Curve 302 represents the RI relationship curve under normal contact conditions of the target terminals at high temperatures. It can be seen that the increase in temperature leads to a uniform increase in the overall resistance value of the terminals by about 30%, but the overall shape of the RI curve remains highly similar to the curve at room temperature. This is a typical characteristic of the effect of temperature change on conductor resistivity. Curve 303 represents the RI relationship curve under slightly loose terminal conditions. It can be seen that the slightly loose condition not only leads to a significant increase in terminal resistance but also exhibits obvious current dependence, especially in the low current region (less than 5A), where the resistance value increases sharply, and the shape of the RI curve changes fundamentally.

[0057] This invention utilizes the characteristic differences in resistance changes caused by the above-mentioned different factors, and combines ambient temperature data and real-time power data to correct the preliminary contact status judgment results. It can effectively distinguish between normal resistance changes caused by increased ambient temperature and abnormal resistance changes caused by loose terminals, reduce the probability of misjudgment caused by temperature interference, and improve the accuracy of contact status diagnosis.

[0058] In some optional embodiments, the present invention further includes a baseline self-learning step for establishing a standard characteristic quantity reference for the target terminals. After the initial installation of the photovoltaic inverter is completed and its normal operation is confirmed, or after routine maintenance, terminal tightening, and other operations are completed, the system automatically enters a preset baseline learning period. During this learning period, the system continuously collects voltage and current signals of the target terminals under different operating conditions in a reliable conductive state, and establishes a baseline resistance model for each target terminal based on the collected normal operation data.

[0059] The baseline resistance model includes at least a resistance-current relationship curve and a resistance-temperature compensation model. The resistance-current relationship curve characterizes the inherent characteristics of the dynamic contact resistance of the target terminal under normal contact conditions, varying with load current, and serves as a benchmark for comparing subsequent real-time measured dynamic contact resistance values. The resistance-temperature compensation model, combined with collected ambient temperature data or inverter internal temperature data, establishes a correlation between contact resistance and temperature, used to correct resistance values ​​measured under different temperature conditions and eliminate the influence of ambient temperature changes on conductor resistivity.

[0060] Through the aforementioned baseline self-learning process, this invention can establish a normal state benchmark for the target terminal, eliminating the influence of individual differences caused by factors such as manufacturing tolerances, installation process variations, or material characteristics on the diagnostic results. Simultaneously, the introduction of a resistance and temperature compensation model can improve the accuracy of contact resistance measurements under different ambient temperatures, thereby enhancing the accuracy of contact state assessment.

[0061] This embodiment also provides a computer program product 10, a computer-readable storage medium 20, and a computer device 30. Figure 10 This is a schematic diagram of a computer program product 10 according to an embodiment of the present invention. Figure 11 This is a schematic diagram of a computer-readable storage medium 20 according to an embodiment of the present invention. Figure 12 This is a schematic diagram of a computer device 30 according to an embodiment of the present invention. The computer program product 10 includes a computer program 11, which, when executed by the processor 32, implements the steps of the photovoltaic inverter terminal contact state monitoring method described above. A computer-readable storage medium 20 stores the computer program 11 thereon, which, when executed by the processor 32, implements the steps of the photovoltaic inverter terminal contact state monitoring method described above. The computer device 30 may include a memory 31, a processor 32, and the computer program 11 stored in the memory 31 and running on the processor 32.

[0062] The computer program 11 used to perform the operations of this invention may be assembly instructions, Instruction Set Architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, integrated circuit configuration data, or source code or object code written in any combination of one or more programming languages ​​and procedural programming languages. The computer program 11 may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a Local Area Network (LAN) or Wide Area Network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of this invention, electronic circuits, including, for example, programmable logic circuits, Field-Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), may execute computer-readable program instructions to personalize the electronic circuits by utilizing state information from computer-readable program instructions.

[0063] For the purposes of this embodiment, computer program product 10 is a related product containing computer program 11. For the purposes of this embodiment, computer-readable storage medium 20 is a tangible device capable of holding and storing computer program 11, and can be any device capable of containing, storing, communicating, propagating, or transmitting program 11 for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable storage medium 20 include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable optical disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, floppy disk, mechanical encoding device, and any suitable combination thereof.

[0064] Computer device 30 can be, for example, a server, desktop computer, laptop computer, tablet computer, or smartphone. In some examples, computer device 30 can be a cloud computing node. Computer device 30 can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., that perform specific tasks or implement specific abstract data types. Computer device 30 can be implemented in a distributed cloud computing environment where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can reside on local or remote computing system storage media, including storage devices.

[0065] Computer device 30 may include a processor 32 adapted to execute stored instructions and a memory 31 that provides temporary storage space for the operation of instructions during operation. The processor 32 may be a single-core processor, a multi-core processor, a computing cluster, or any other configuration. The memory 31 may include random access memory (RAM), read-only memory, flash memory, or any other suitable storage system.

[0066] Computer device 30 may also include a network adapter / interface and an input / output (I / O) interface. The I / O interface allows external devices that can be connected to the computer device to input and output data. The network adapter / interface provides communication between the computer device and a network, typically represented as a communication network.

[0067] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for monitoring the terminal contact status of a photovoltaic inverter, characterized in that, include: Acquire the voltage and current signals of the target terminals during the operation of the photovoltaic inverter; Calculate the dynamic contact resistance of the target terminal based on the voltage signal and the current signal; Extract measurement characteristic quantities from the dynamic contact resistance; The measured characteristic quantity is used to characterize the conductivity state of the target terminal; The measured characteristic quantities include: steady-state resistance value, resistance change rate, and voltage distortion characteristic value at the current zero-crossing point; Obtain the standard characteristic quantities of the target terminal under a reliable conductive state; the standard characteristic quantities include: standard resistance value of conduction, standard resistance change rate, and standard voltage distortion value at the current zero crossing point; The contact state of the target terminal is obtained by comparing the measured characteristic quantity with the standard characteristic quantity. The step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal includes: Determine whether the difference between the steady-state resistance value and the conductive standard resistance value is less than a preset difference threshold; If the difference between the steady-state resistance value and the conductive standard resistance value is less than the preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is less than the preset first conversion rate threshold. If the difference between the resistance change rate and the standard resistance change rate is less than the first conversion rate threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than a preset distortion threshold. If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is less than the preset distortion threshold, the contact state is determined to be normal. The step of comparing the measured characteristic quantity with the standard characteristic quantity to obtain the contact state of the target terminal further includes: If the difference between the resistance change rate and the standard resistance change rate is greater than or equal to the first conversion rate threshold, the contact state is determined to be slightly loose or aged. If the difference between the steady-state resistance value and the standard resistance value is greater than or equal to the preset difference threshold, determine whether the difference between the voltage distortion characteristic value at the current zero-crossing point and the standard voltage distortion value at the current zero-crossing point is less than the preset distortion threshold. If the difference between the voltage distortion characteristic value at the current zero-crossing point and the voltage distortion standard value at the current zero-crossing point is greater than or equal to the preset distortion threshold, the contact state is determined to be a severely loose state. If the difference between the steady-state resistance value and the conductive standard resistance value is greater than or equal to the preset difference threshold, determine whether the difference between the resistance change rate and the standard resistance change rate is greater than the preset second conversion rate threshold. If the difference between the resistance change rate and the standard resistance change rate is greater than the second conversion rate threshold, the contact state is determined to be an overheating risk state.

2. The method for monitoring the terminal contact status of a photovoltaic inverter according to claim 1, characterized in that, After the step of obtaining the contact state of the target terminal, the method further includes: Based on the contact state, corresponding graded protection actions are executed; wherein... If the contact condition is slightly loose or aged, record the abnormal information and output an operation and maintenance inspection alarm. If the contact condition is described as severely loose, reduce the input power of the photovoltaic inverter. If the contact state is at risk of overheating, disconnect the branch in the photovoltaic inverter corresponding to the target terminal.

3. The method for monitoring the terminal contact status of a photovoltaic inverter according to claim 1, characterized in that, Before the step of calculating the dynamic contact resistance of the target terminal based on the voltage signal and the current signal, the method further includes: Determine whether the current signal is greater than a preset current threshold; If so, perform the operation of calculating the dynamic contact resistance of the target terminal based on the voltage signal and the current signal.

4. The method for monitoring the terminal contact status of a photovoltaic inverter according to claim 1, characterized in that, After the step of obtaining the contact state of the target terminal, the method further includes: Acquire the ambient temperature data of the target terminal, the real-time power data of the photovoltaic inverter, and the historical operating data of the target terminal; The contact state is corrected based on the contact state, the ambient temperature data, the real-time power data, and the historical operating data; wherein... The ambient temperature data is used to distinguish the causes of the increase in dynamic contact resistance and to determine whether the cause is due to changes in ambient temperature or loosening of the target terminal. The real-time power data is used to analyze the characteristics of the dynamic contact resistance as the load changes; The historical operating data is used to analyze the changing trend of the dynamic contact resistance.

5. The method for monitoring the terminal contact status of a photovoltaic inverter according to claim 1, characterized in that, After the step of acquiring the voltage and current signals of the target terminal during the operation of the photovoltaic inverter, the method further includes: Determine whether the amplitude of the voltage signal change is greater than a preset voltage change threshold, or whether the amplitude of the current signal change is greater than a preset current change threshold; If so, start the acquisition mode and acquire the waveforms of the voltage signal and the current signal within a preset time period before and after the trigger time; The resistance spikes and voltage glitches are determined based on the waveforms of the voltage signal and the current signal. The contact state is corrected based on the resistance spikes and voltage glitches.

6. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the method for monitoring the terminal contact status of a photovoltaic inverter as described in any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that... When the computer program is executed by the processor, it implements the steps of the method for monitoring the terminal contact status of a photovoltaic inverter as described in any one of claims 1 to 5.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method for monitoring the terminal contact status of a photovoltaic inverter as described in any one of claims 1 to 5.

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