Photovoltaic input loop insulation fault diagnosis method based on relay switching

Abstract

The invention discloses a photovoltaic input loop insulation fault diagnosis method based on relay switching, and relates to the technical field of insulation fault detection. The photovoltaic input loop insulation fault diagnosis method based on relay switching comprises the following steps: monitoring fluctuation of photovoltaic input voltage; insulation impedance accuracy monitoring; and detecting an insulation impedance fault. Under the condition that a photovoltaic input loop is connected, photovoltaic input voltage volatility monitoring is carried out, then insulation resistance accuracy monitoring is carried out after photovoltaic input voltage volatility monitoring is finished, and whether insulation resistance accuracy optimization is carried out or not is judged. And finally, after insulation impedance accuracy monitoring is finished, insulation impedance fault detection is carried out, so that the effect of improving the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching is achieved. The problem of low signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation fault detection, and particularly to a method for diagnosing insulation faults in a photovoltaic input circuit based on relay switching. Background Art

[0002] As an important part of renewable energy, the stable operation of a photovoltaic power station is of great significance for ensuring power supply. However, photovoltaic power stations are mostly built outdoors, and environmental factors such as temperature, humidity, and pollution are likely to cause a decline in insulation performance, thus triggering insulation faults. As a common electrical control component, a relay has the advantages of fast switching speed and high reliability. In the diagnosis of insulation faults in a photovoltaic input circuit, relay switching technology can play an important role: through the rapid switching of the relay, rapid detection and isolation of different parts of the photovoltaic input circuit can be achieved, improving the response speed of fault diagnosis.

[0003] Existing methods mainly adopt a one-by-one detection method in a multi-channel insulation impedance detection circuit. This one-by-one detection method will occupy many sampling ports of the control chip, thus having relatively high requirements for the chip, and the corresponding sampling circuit is more complex.

[0004] For example, a DC insulation system for detecting AC intrusion into DC faults and a method disclosed in the invention patent announcement with the publication number of CN114062959B include: a first DC bus and a second DC bus. In this application, by setting two DC buses, the first DC bus serves as the main DC power supply system, and the second DC bus serves as the backup DC power supply system, and the two cannot work simultaneously. When AC components are detected in one of the buses, it automatically switches to the other DC bus. Additionally, when AC components are detected by the first AC component detection capacitor or the second AC component detection capacitor, the first alarm or the second alarm automatically alarms, and remote alarm is also carried out through a remote monitoring terminal.

[0005] For example, a method and device for diagnosing a high-voltage relay disclosed in the invention patent announcement with the publication number of CN112034333B include obtaining the magnitude relationship between the voltage value at the input end and the voltage value at the output end of each high-voltage relay; when it is determined according to the magnitude relationship that the voltage values at the input end and the output end are equal, controlling the detection relay to be in a closed state; and when the detection relay is in a closed state, obtaining the state of the high-voltage relay according to the current voltage value at the input end and the current voltage value at the output end.

[0006] However, in the process of implementing the technical solutions of the present invention in the embodiments of the present application, it is found that the above technologies have at least the following technical problems:

[0007] In the prior art, for a control chip, the number of ADC ports used for sampling is limited. Under the condition of multiple inputs, it is necessary to sample the voltage, current signals and insulation impedance values of each path, which affects the sampling of other key signals. When detecting the insulation impedance of multiple photovoltaic inputs, the resources occupied by insulation impedance sampling may interfere with the timeliness of signal sampling, resulting in low accuracy of signal sampling in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching. Summary of the Invention

[0008] By providing a method for diagnosing insulation faults in a photovoltaic input circuit based on relay switching, the embodiment of the present application solves the problem of low accuracy of signal sampling in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching in the prior art, and realizes the improvement of the accuracy of signal sampling in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching.

[0009] The embodiment of the present application provides a method for diagnosing insulation faults in a photovoltaic input circuit based on relay switching, including the following steps: S1, when the photovoltaic input circuit is connected, monitor the volatility of the photovoltaic input voltage to determine whether to perform delay matching optimization. The monitoring of the volatility of the photovoltaic input voltage is used to quantitatively evaluate the influence degree of the photovoltaic input on the stability of the sampling signal, and the delay matching optimization is used to improve the stability of the sampling signal; S2, after the monitoring of the volatility of the photovoltaic input voltage is completed, monitor the accuracy of the insulation impedance to quantitatively evaluate the accuracy of the insulation impedance sampling signal, and determine whether to perform insulation impedance accuracy optimization. The insulation impedance accuracy optimization is used to improve the accuracy of the insulation impedance sampling signal; S3, after the monitoring of the accuracy of the insulation impedance is completed, perform insulation impedance fault detection. The insulation impedance fault detection is used to judge the working condition of the photovoltaic input circuit.

[0010] One or more technical solutions provided in the embodiment of the present application have at least the following technical effects or advantages:

[0011] 1. By monitoring the volatility of the photovoltaic input voltage when the photovoltaic input circuit is connected, then monitoring the accuracy of the insulation impedance and determining whether to perform insulation impedance accuracy optimization after the monitoring of the volatility of the photovoltaic input voltage is completed, and finally performing insulation impedance fault detection after the monitoring of the accuracy of the insulation impedance is completed, the stability of the insulation impedance fault detection is improved, and further the accuracy of signal sampling in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching is improved, effectively solving the problem of low accuracy of signal sampling in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching in the prior art.

[0012] 2. By performing sampling signal delay analysis on the sampling signal delay fault evaluation parameter and the preset sampling signal delay fault evaluation parameter to obtain the sampling delay evaluation value, when the sampling delay evaluation value is greater than the preset sampling delay threshold, sampling delay optimization is performed, thereby achieving accurate evaluation of the photovoltaic signal sampling delay situation, and further improving the reliability of the photovoltaic signal sampling delay situation evaluation.

[0013] 3. By performing numerical conversion based on the obtained qualified photovoltaic sampling signal to obtain the insulation impedance value, when the insulation impedance value is consistent with the theoretically calculated value, a prompt to allow the loop to start is sent, and when the insulation impedance value is inconsistent with the theoretically calculated value, a loop fault prompt and a prompt not to allow the loop to start are sent, thereby improving the reliability of insulation impedance fault detection and further improving the accuracy of insulation impedance fault detection. Description of the Drawings

[0014] Figure 1 It is a flowchart of a method for diagnosing insulation faults in a photovoltaic input loop based on relay switching provided by an embodiment of the present application;

[0015] Figure 2 It is a specific flowchart provided by an embodiment of the present application;

[0016] Figure 3 It is a circuit diagram of a multi-channel input insulation impedance detection circuit provided by an embodiment of the present application. Detailed Embodiments

[0017] The embodiment of the present application provides a method for diagnosing insulation faults in a photovoltaic input loop based on relay switching, which solves the problem of low signal sampling accuracy in the process of diagnosing insulation faults in a photovoltaic input loop based on relay switching in the prior art. By monitoring the volatility of the photovoltaic input voltage to determine whether to perform delay matching optimization when the photovoltaic input loop is connected, and then, after the monitoring of the volatility of the photovoltaic input voltage is completed, monitoring the accuracy of the insulation impedance to quantitatively evaluate the accuracy of the insulation impedance sampling signal and determine whether to perform insulation impedance accuracy optimization. Finally, after the monitoring of the insulation impedance accuracy is completed, insulation impedance fault detection is performed, thereby improving the stability of insulation impedance fault detection and improving the signal sampling accuracy in the process of diagnosing insulation faults in a photovoltaic input loop based on relay switching.

[0018] The technical solution in the embodiment of the present application is to solve the problem of low signal sampling accuracy in the process of diagnosing insulation faults in a photovoltaic input loop based on relay switching. The general idea is as follows:

[0019] By monitoring the volatility of the photovoltaic input voltage when the photovoltaic input circuit is connected, then after the monitoring of the volatility of the photovoltaic input voltage is completed, monitoring the accuracy of the insulation impedance and determining whether to optimize the accuracy of the insulation impedance, and finally after the monitoring of the accuracy of the insulation impedance is completed, detecting the insulation impedance fault, the effect of improving the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching is achieved.

[0020] To better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0021] As Figure 1 shown, it is a flowchart of a method for diagnosing insulation faults in a photovoltaic input circuit based on relay switching provided by an embodiment of the present application. The method includes the following steps: S1, monitoring the volatility of the photovoltaic input voltage: When the photovoltaic input circuit is connected, monitor the volatility of the photovoltaic input voltage to determine whether to perform delay matching optimization. The monitoring of the volatility of the photovoltaic input voltage is used to quantitatively evaluate the influence degree of the photovoltaic input on the stability of the sampling signal, and the delay matching optimization is used to improve the stability of the sampling signal; S2, monitoring the accuracy of the insulation impedance: After the monitoring of the volatility of the photovoltaic input voltage is completed, monitor the accuracy of the insulation impedance to quantitatively evaluate the accuracy of the insulation impedance sampling signal, and determine whether to optimize the accuracy of the insulation impedance. The optimization of the accuracy of the insulation impedance is used to improve the accuracy of the insulation impedance sampling signal; S3, detecting the insulation impedance fault: After the monitoring of the accuracy of the insulation impedance is completed, detect the insulation impedance fault. The detection of the insulation impedance fault is used to determine the working condition of the photovoltaic input circuit.

[0022] In this embodiment, as Figure 2As shown, it is the specific flowchart provided by the embodiment of the present application. By monitoring the volatility of the photovoltaic input voltage, the photovoltaic input voltage fluctuation value is obtained. When the monitored photovoltaic input voltage fluctuation value is greater than the preset photovoltaic voltage fluctuation threshold, it indicates that the photovoltaic input voltage fluctuation situation interferes with the accuracy of the insulation impedance fault detection, and delay matching optimization is performed to improve the stability of the sampling signal. By monitoring the accuracy of the insulation impedance, the relay switching accuracy index and the sampling delay evaluation value are obtained. When the monitored relay switching accuracy index is not greater than the preset relay switching accuracy threshold, relay switching accuracy optimization is performed. When the monitored sampling delay evaluation value is greater than the preset sampling delay threshold, sampling delay optimization is performed. By performing insulation impedance fault detection, qualified photovoltaic sampling signals and corresponding insulation impedance values are obtained. Whether the insulation impedance detection is normal is judged according to the insulation impedance value, and the corresponding insulation impedance value is stored in the register. Through the cooperation of photovoltaic input voltage volatility monitoring, insulation impedance accuracy monitoring, and insulation impedance fault detection, it helps to improve the stability of the insulation impedance fault detection, and thus achieves the effect of improving the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching.

[0023] In the case of multiple photovoltaic inputs, voltage fluctuations may cause instability of the sampling signal, affecting the accuracy of the insulation impedance detection. Through delay matching optimization, the influence of voltage fluctuations on the sampling signal can be reduced, making the sampling signal more stable, thereby improving the accuracy of the insulation impedance detection. Through the collaborative work of photovoltaic input voltage volatility monitoring, insulation impedance accuracy monitoring, and insulation impedance fault detection, the stability of the insulation impedance fault detection is improved, and thus the safe and reliable operation of the entire photovoltaic system is ensured.

[0024] Further, when the photovoltaic input circuit is connected, monitor the volatility of the photovoltaic input voltage to determine whether to perform delay matching optimization. The specific process is as follows: Monitor the photovoltaic input voltage fluctuation value, which is represented by the difference between the maximum and minimum values of the photovoltaic input voltage during a preset time period. The photovoltaic input voltage fluctuation value represents the data reflecting the fluctuation degree of the photovoltaic input voltage during the preset time period through the difference between the maximum and minimum values of the photovoltaic input voltage; Determine whether to perform delay matching optimization based on the photovoltaic input voltage fluctuation value; When the photovoltaic input voltage fluctuation value is not greater than the preset photovoltaic voltage fluctuation threshold obtained from the database, do not perform delay matching optimization and continue to monitor the accuracy of the insulation impedance, where the preset photovoltaic voltage fluctuation threshold is represented by the photovoltaic input voltage fluctuation value in the historical time period; When the photovoltaic input voltage fluctuation value is greater than the preset photovoltaic voltage fluctuation threshold obtained from the database, perform delay matching optimization, which means sending a prompt to the preset personnel to gradually increase the stable time after the relay action. Among them, the preset maximum stable time is represented by the maximum value of the stable time after the relay action in the historical time period; When the stable time after the relay action reaches the preset maximum stable time, send a prompt to cut off the circuit.

[0025] It should be added that Figure 3 This is the circuit diagram of the multi-input insulation impedance detection circuit provided by the embodiment of the present application. Among them, PE represents the chassis ground, and Insul_AD represents the insulation impedance sampling value; After the monitoring of the photovoltaic input voltage volatility is completed, monitor the accuracy of the insulation impedance to quantitatively evaluate the accuracy of the insulation impedance sampling signal. The specific process is as follows: Send a prompt to the preset personnel to obtain the first sampling signal, which represents the signal obtained by forming a first resistance circuit after the relay to be energized is energized and then sent to the control chip for sampling through the operational amplifier U; The relay to be energized includes relays K1, K2....Kn (n represents the total number of relays to be energized); Send a prompt to the preset personnel to obtain the second sampling signal, which represents the signal obtained by forming a second resistance circuit after the relay K is actuated and then sent to the control chip for sampling through the operational amplifier U; The first resistance circuit represents a circuit including resistors R1, R2, and R3; The second resistance circuit represents a circuit including resistors R1, R3, and the relay K.

[0026] In this embodiment, when the input impedance of the first photovoltaic path is present, the relay K1 is actuated, PV1+ is connected, and resistors R1, R2, and R3 form a first resistor loop. Through resistors R4, R5, R6 and the operational amplifier U, proportional reduction is performed to convert the high-voltage signal corresponding to the first resistor loop into a low-voltage signal to obtain a first sampling signal. Then, the relay K is actuated, such that resistors R1, R3, and the relay K form a second resistor loop. Through resistors R4, R5, R6 and the operational amplifier U, proportional reduction is performed to convert the high-voltage signal corresponding to the second resistor loop into a low-voltage signal to obtain a second sampling signal, and so on. The first sampling signal and the second sampling signal at the time of the second photovoltaic input impedance are sequentially obtained. By monitoring the insulation impedance accuracy of the photovoltaic input, the insulation impedance sampling condition of the photovoltaic input is comprehensively evaluated, ensuring the reliability and stability of the entire insulation impedance monitoring, and further improving the signal sampling accuracy during the insulation fault diagnosis process of the photovoltaic input loop based on relay switching.

[0027] Furthermore, the insulation impedance accuracy monitoring includes relay switching fault monitoring, sampling signal delay fault monitoring, and relay K disconnection delay fault monitoring; the insulation impedance accuracy optimization includes relay switching accuracy optimization and sampling delay optimization; the relay switching fault monitoring represents a quantitative evaluation of the relay switching accuracy by jointly obtaining the relay switching parameters and the preset relay switching parameters; the sampling signal delay fault monitoring represents a quantitative evaluation of the photovoltaic signal sampling delay condition by jointly obtaining the sampling signal delay fault evaluation parameters and the preset sampling signal delay fault evaluation parameters.

[0028] Among them, the relay switching parameters include the relay actuation time, the final value of the relay contact resistance, the relay pull-in time, and the input photovoltaic voltage change rate; the actuation time of the relay K in a preset time period is monitored by an oscilloscope and a timer as the relay actuation time; the contact resistance of the relay contacts in the final state in a preset time period is monitored by a loop resistance tester as the final value of the relay contact resistance; the pull-in time of the relay to be pulled in in a preset time period is monitored by an oscilloscope and a timer as the relay pull-in time; the absolute value of the difference between the initial-state photovoltaic input voltage and the final-state photovoltaic input voltage in a preset time period is monitored by a voltmeter and an oscilloscope, and the result of the ratio operation with the preset time period is used as the input photovoltaic voltage change rate.

[0029] Specifically, the preset relay switching parameters include the preset relay operation time, the final value of the preset relay contact resistance, the preset relay pull-in time, and the preset photovoltaic input voltage change rate. Among them, the units of the relay operation time, the relay pull-in time, the preset relay operation time, and the preset relay pull-in time are all milliseconds; the units of the relay contact resistance final value and the preset relay contact resistance final value are both ohms, and the units of the input photovoltaic voltage change rate and the preset input photovoltaic voltage change rate are both volts per second.

[0030] Among them, the sampling signal delay fault evaluation parameters include the relay switching delay duration, the number of photovoltaic signal samplings, the insulation sampling interval, and the ADC conversion time. The difference between the actual switching time of relay k and the preset switching duration within a preset time period (only considering data greater than 0) is monitored by an oscilloscope and a timer as the relay switching delay duration; the number of times of sampling the photovoltaic signal within a preset time period is monitored by an oscilloscope as the number of photovoltaic signal samplings; the sampling time interval between the first sampling signal and the second sampling signal within a preset time period is monitored by a timer as the insulation sampling interval; the time required for the ADC to convert the analog signal to a digital signal within a preset time period is monitored by an oscilloscope and a timer as the ADC conversion time.

[0031] Specifically, the preset sampling signal delay fault evaluation parameters include the preset relay switching delay duration, the preset number of photovoltaic signal samplings, the preset insulation sampling interval, and the preset ADC conversion time. Among them, the units of the relay switching delay duration, the insulation sampling interval, the preset relay switching delay duration, and the preset insulation sampling interval are all milliseconds, the units of the number of photovoltaic signal samplings and the preset number of photovoltaic signal samplings are both times, and the units of the ADC conversion time and the preset ADC conversion time are both microseconds.

[0032] It should be added that the aforementioned database is a database for storing various setting data in a photovoltaic input circuit insulation fault diagnosis method based on relay switching provided by an embodiment of the present application. The database includes, but is not limited to, the preset relay operation time, the final value of the preset relay contact resistance, the preset relay pull-in time, etc. The various values therein are directly set by technicians. For example, the preset relay switching parameters and the preset sampling signal delay fault evaluation parameters are respectively represented by the average values of the relay switching parameters and the sampling signal delay fault evaluation parameters in the corresponding historical time periods in the database.

[0033] In this embodiment, by monitoring the relay switching parameters and the sampling signal delay fault evaluation parameters, the accuracy of relay switching is quantitatively evaluated; by monitoring the insulation impedance accuracy and optimizing the insulation impedance accuracy, it helps to improve the accuracy and timeliness of the sampling signal, and thus improves the signal sampling accuracy in the photovoltaic input circuit insulation fault diagnosis process based on relay switching.

[0034] Further, the specific process of relay switching fault monitoring is as follows: First, by analyzing the proportion degree of the preset relay action time and the relay action time, the relay action time and the accuracy reflection value are obtained, which is used to reflect the influence degree of the relay action time on the relay switching accuracy; specifically, the expression of the relay action time and the accuracy reflection value is In the formula, QH1(F) represents the relay action time and the accuracy reflection value in the F-th preset time period, QHT1(F) represents the relay action time in the F-th preset time period, QHT1(0) represents the preset relay action time, F = 1, 2,..., Y, F represents the number of the preset time period, and Y represents the total number of the preset time periods.

[0035] Next, by analyzing the proportion degree of the preset relay contact resistance final value and the relay contact resistance final value, the relay contact resistance and the accuracy reflection value are obtained, which is used to reflect the influence degree of the relay contact resistance final value on the relay switching accuracy; specifically, the expression of the relay contact resistance and the accuracy reflection value is In the formula, DZ(F) represents the relay contact resistance final value in the F-th preset time period, and DZ(0) represents the preset relay contact resistance final value.

[0036] Then, by analyzing the proportion degree of the preset relay pull-in time and the relay pull-in time, the relay pull-in time and the accuracy reflection value are obtained, which is used to reflect the influence degree of the relay pull-in time on the relay switching accuracy; specifically, the expression of the relay pull-in time and the accuracy reflection value is In the formula, QH3(F) represents the relay pull-in time and the accuracy reflection value in the F-th preset time period, XHT1(F) represents the relay pull-in time in the F-th preset time period, and XHT1(0) represents the preset relay pull-in time.

[0037] Next, by analyzing the proportion degree of the preset input photovoltaic voltage change rate and the input photovoltaic voltage change rate, the photovoltaic voltage change and the accuracy reflection value are obtained, which is used to reflect the influence degree of the input photovoltaic voltage change rate on the relay switching accuracy; specifically, the expression of the photovoltaic voltage change and the accuracy reflection value is In the formula, QH4(F) represents the photovoltaic voltage change and the accuracy reflection value in the F-th preset time period, ΔGFV1(F) represents the input photovoltaic voltage change rate in the F-th preset time period, and ΔGFV1(0) represents the preset input photovoltaic voltage change rate.

[0038] Finally, after performing weighted operations on the relay switching data and the corresponding preset relay switching weights, coupling processing is carried out to obtain the relay switching accuracy index, which is used to reflect the comprehensive influence of the relay switching parameters and the preset relay switching parameters on the relay switching accuracy; the relay switching data includes the relay operation time and the accuracy reflection value, the relay contact resistance and the accuracy reflection value, the relay pull-in time and the accuracy reflection value, and the photovoltaic voltage change and the accuracy reflection value; the preset relay switching weights include the preset relay operation time weight value, the preset relay contact resistance weight value, the preset relay pull-in time weight value, and the preset photovoltaic voltage change weight value, which are used to reflect the influence of the relay switching data on the relay switching accuracy index.

[0039] Among them, the relay switching accuracy index is obtained by the following method:

[0040] QH(F) = δ1×QH1(F) + δ2×QH2(F) + δ3×QH3(F) + δ4×QH4(F);

[0041] In the formula, QH(F) represents the relay switching accuracy index of the F-th preset time period, δ1 represents the preset relay operation time weight value, δ2 represents the preset relay contact resistance weight value, δ3 represents the preset relay pull-in time weight value, and δ4 represents the preset photovoltaic voltage change weight value.

[0042] It should be explained that a set of mapping groups containing mapping sets is obtained from the database, and the mapping relationships in the mapping sets can be one-to-one or many-to-one relationships, and this mapping set is used to reflect the mapping relationship between the relay switching data and the corresponding preset relay switching weights; inputting the real-time relay switching data into the corresponding mapping group can obtain the preset relay switching weights; for example, the value range of the weights is 0-1; in this embodiment, the relay switching data considered are all greater than 0.

[0043] In this embodiment, the accurate index of relay switching is further obtained through the analysis of relay switching data. The larger the action time of the relay and the accuracy reflection value, the greater the influence of the relay action time on the switching accuracy of the relay, resulting in a larger accurate index of relay switching; the larger the contact resistance of the relay and the accuracy reflection value, the stronger the influence of the final state value of the relay contact resistance on the switching accuracy of the relay, resulting in a larger accurate index of relay switching; the larger the pull-in time of the relay and the accuracy reflection value, the stronger the influence of the relay pull-in time on the switching accuracy of the relay, resulting in a larger accurate index of relay switching; the larger the change in photovoltaic voltage and the accuracy reflection value, the stronger the influence of the input photovoltaic voltage change rate on the switching accuracy of the relay, resulting in a larger accurate index of relay switching; in summary, there is a positive proportional relationship between the relay switching data and the accurate index of relay switching in this embodiment.

[0044] In this embodiment, the monitored relay switching parameters do not exist independently and are interrelated. Correlation analysis is required to evaluate their combined effects. The longer the pull-in time of the relay, it may cause the action time of relay k to extend, reduce the switching speed of the relay, and then lead to a larger action time of the relay; the larger the final state value of the contact resistance of the relay contact, more heat and voltage drop may be generated during the switching process, and then lead to an increase in the action time of the relay; the larger the change rate of the photovoltaic voltage, it may cause relay k to be subjected to voltage impact during the switching process, which may further affect the action time of relay k and the pull-in time of the relay to be pulled in, and then lead to an increase in the action time of the relay and the pull-in time of the relay. By analyzing the comprehensive influence between parameters, the accurate evaluation of the relay switching accuracy is realized, and then the effect of improving the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching is achieved.

[0045] Comprehensively, it can be seen that the longer the pull-in time of the relay means that the pull-in time of the relay and the accuracy reflection value are smaller, which may lead to a larger action time of the relay, that is, the action time of the relay and the accuracy reflection value are smaller; the larger the final state value of the contact resistance of the relay contact, it means that the contact resistance of the relay and the accuracy reflection value are smaller, which may lead to an increase in the action time of the relay, that is, the action time of the relay and the accuracy reflection value are smaller; the larger the change rate of the photovoltaic voltage, it means that the change in photovoltaic voltage and the accuracy reflection value are smaller, which may lead to an increase in the action time of the relay and the pull-in time of the relay, that is, the action time of the relay and the accuracy reflection value and the pull-in time of the relay and the accuracy reflection value are smaller; it can further reflect the comprehensive influence between the action time of the relay and the accuracy reflection value, the contact resistance of the relay and the accuracy reflection value, the pull-in time of the relay and the accuracy reflection value, and the change in photovoltaic voltage and the accuracy reflection value.

[0046] Further, the specific process of optimizing the relay switching accuracy is as follows: Compare the relay switching accuracy index with the preset relay switching accuracy threshold obtained from the database; when the relay switching accuracy index is not greater than the preset relay switching accuracy threshold, mark the corresponding loop as a relay switching failure loop and perform relay switching accuracy optimization, where the preset relay switching accuracy threshold is represented by the average value of the relay switching accuracy index in the historical time period; when the relay switching accuracy index is greater than the preset relay switching accuracy threshold, do not perform relay switching accuracy optimization; the specific steps of relay switching accuracy optimization are as follows: First step, set the contact capacitance, and the contact capacitance setting means gradually increasing the parallel capacitance of the contacts; Second step, set the sampling input terminal resistance, and the sampling input terminal resistance setting means gradually increasing the resistance connected in parallel at the sampling input terminal; when the monitored relay switching accuracy index is greater than the preset relay switching accuracy threshold, stop performing relay switching accuracy optimization, otherwise send an alarm prompt to the preset personnel.

[0047] In this embodiment, when receiving a prompt that the relay switching accuracy index is not greater than the preset relay switching accuracy threshold, perform relay switching accuracy optimization: According to the proportional relationship between the relay switching accuracy index and the preset relay switching accuracy threshold, gradually increase the parallel capacitance of the contacts in a corresponding preset ratio, and gradually increase the resistance connected in parallel at the sampling input terminal in a corresponding preset ratio; when it is monitored that the relay switching accuracy index is greater than the preset relay switching accuracy threshold, stop performing relay switching accuracy optimization; By performing relay switching accuracy optimization on the relay switching failure loop, it helps to reduce faults and anomalies during the relay switching process, improve the stability and reliability of the system, thus ensuring the normal operation of the photovoltaic input loop, and further achieving the effect of improving the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching.

[0048] Further, the sampling signal delay fault monitoring means performing sampling signal delay analysis on the sampling signal delay fault evaluation parameter and the preset sampling signal delay fault evaluation parameter; the sampling signal delay analysis includes relay switching delay analysis, photovoltaic signal sampling times delay analysis, insulation sampling interval delay analysis, ADC conversion delay analysis, and comprehensive sampling delay analysis.

[0049] Among them, the relay switching delay analysis means performing a ratio degree analysis on the relay switching delay duration and the preset relay switching delay duration to obtain a relay switching delay reflection value, which is used to reflect the influence degree of the relay switching delay duration on the photovoltaic signal sampling delay situation. Specifically, the expression of the relay switching delay reflection value is Where CYPG1(F) represents the relay switching delay reflection value in the F-th preset time period, QHYC(F) represents the relay switching delay duration in the F-th preset time period, QHYC(0) represents the preset relay switching delay duration, F = 1, 2,..., Y, F represents the number of the preset time period, and Y represents the total number of the preset time periods.

[0050] Among them, the photovoltaic signal sampling times delay analysis means analyzing the ratio between the photovoltaic signal sampling times and the preset photovoltaic signal sampling times to obtain the photovoltaic signal sampling times reflection value, which is used to reflect the influence degree of the photovoltaic signal sampling times on the photovoltaic signal sampling delay situation; specifically, the expression of the photovoltaic signal sampling times reflection value is Where CYPG2(F) represents the photovoltaic signal sampling times reflection value in the F-th preset time period, CYP(F) represents the photovoltaic signal sampling times in the F-th preset time period, and CYP(0) represents the preset photovoltaic signal sampling times.

[0051] Among them, the insulation sampling interval delay analysis means analyzing the ratio between the preset insulation sampling interval and the insulation sampling interval to obtain the insulation sampling interval reflection value, which is used to reflect the influence degree of the insulation sampling interval on the photovoltaic signal sampling delay situation; specifically, the expression of the insulation sampling interval reflection value is Where CYPG3(F) represents the insulation sampling interval reflection value in the F-th preset time period, CYT(F) represents the insulation sampling interval in the F-th preset time period, and CYT(0) represents the preset insulation sampling interval.

[0052] Among them, the ADC conversion delay analysis means analyzing the ratio between the ADC conversion time and the preset ADC conversion time to obtain the ADC conversion time reflection value, which is used to reflect the influence degree of the ADC conversion time on the photovoltaic signal sampling delay situation; specifically, the expression of the ADC conversion time reflection value is Where CYPG4(F) represents the ADC conversion time reflection value in the F-th preset time period, ADZ(F) represents the ADC conversion time in the F-th preset time period, and ADZ(0) represents the preset ADC conversion time.

[0053] Among them, the comprehensive sampling delay analysis means that after performing weighted operations on the sampling signal delay data, the relay switching accuracy index, and the corresponding preset sampling signal delay weight, coupling processing is carried out to obtain a sampling delay evaluation value, which is used to reflect the comprehensive effect of the sampling signal delay fault evaluation parameter and the preset sampling signal delay fault evaluation parameter on the photovoltaic signal sampling delay situation; the sampling signal delay data includes the relay switching delay reflection value, the photovoltaic signal sampling times reflection value, the insulation sampling interval reflection value, the ADC conversion time reflection value, and the relay switching accuracy index; the preset sampling signal delay weight includes the relay switching delay duration weight value, the photovoltaic signal sampling times weight value, the insulation sampling interval weight value, the relay switching delay duration weight value, and the relay switching accuracy weight value, which is used to reflect the influence degree of the sampling signal delay data on the sampling delay evaluation value.

[0054] Among them, the sampling delay evaluation value is obtained by the following method:

[0055]

[0056] In the formula, CYPG(F) represents the sampling delay evaluation value of the Fth preset time period, QH(F) represents the relay switching accuracy index of the Fth preset time period, α1 represents the relay switching delay duration weight value, α2 represents the photovoltaic signal sampling times weight value, α3 represents the insulation sampling interval weight value, α4 represents the relay switching delay duration weight value, and α5 represents the relay switching accuracy weight value.

[0057] It should be explained that a set of mapping groups containing a mapping set is obtained from the database, and the mapping relationship in the mapping set can be a one-to-one or many-to-one relationship, and this mapping set is used to reflect the mapping relationship between the sampling signal delay data and the corresponding preset sampling signal weight; inputting the real-time sampling signal delay data into the corresponding mapping group can obtain the preset sampling signal weight; for example, the value range of the weight is 0-1; in this embodiment, the sampling signal delay data considered is greater than 0.

[0058] In this embodiment, the sampling delay evaluation value is further obtained through the analysis of the sampling signal delay data. The larger the reflection value of the relay switching delay, the stronger the influence of the relay switching delay duration on the sampling delay of the photovoltaic signal, resulting in a larger sampling delay evaluation value; the larger the reflection value of the number of photovoltaic signal samplings, the stronger the influence of the number of photovoltaic signal samplings on the sampling delay of the photovoltaic signal, resulting in a larger sampling delay evaluation value; the larger the reflection value of the insulation sampling interval, the stronger the influence of the insulation sampling interval on the sampling delay of the photovoltaic signal, resulting in a larger sampling delay evaluation value; the larger the reflection value of the ADC conversion time, the stronger the influence of the ADC conversion time on the sampling delay of the photovoltaic signal, resulting in a larger sampling delay evaluation value; the larger the relay switching accuracy index, the stronger the influence of the relay switching accuracy index on the sampling delay of the photovoltaic signal, resulting in a larger sampling delay evaluation value; in summary, in this embodiment, the sampling signal delay data is directly proportional to the sampling delay evaluation value, and the relay switching accuracy index is inversely proportional to the sampling delay evaluation value.

[0059] In this embodiment, the monitored sampling signal delay fault evaluation parameters do not exist independently and are interrelated. Correlation analysis is required to evaluate their combined effects. The larger the number of photovoltaic signal samplings, the more frequently the relay may need to be switched for sampling, further exacerbating the sampling burden, and thus resulting in a longer relay switching delay duration; the longer the ADC conversion time, the longer the time required for each sampling, and the relay needs to wait for the ADC to complete the conversion before the next switch can be made, which may lead to data overlap and thus a longer relay switching delay duration; the larger the relay switching accuracy index and the smaller the insulation sampling interval, the more frequent the monitoring of the insulation state, which helps to improve the accuracy of relay switching and reduce the number of switches, and thus may lead to a shorter relay switching delay duration; by analyzing the comprehensive influence between the parameters, the accurate evaluation of the relay switching accuracy is achieved, and thus the improvement of the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input circuit based on relay switching is realized.

[0060] Generally speaking, the larger the number of photovoltaic signal samplings, the larger the reflection value of the number of photovoltaic signal samplings, which may lead to a longer relay switching delay duration, that is, the larger the reflection value of the relay switching delay; the longer the ADC conversion time, the longer the reflection value of the ADC conversion time, which may lead to a longer relay switching delay duration, that is, the larger the reflection value of the relay switching delay; the larger the reflection values of the relay switching accuracy index and the insulation sampling interval, the shorter the relay switching delay duration may be, that is, the smaller the reflection value of the relay switching delay; this can further reflect the comprehensive influence among the reflection value of the relay switching delay, the reflection value of the number of photovoltaic signal samplings, the reflection value of the insulation sampling interval, the reflection value of the ADC conversion time, and the relay switching accuracy index.

[0061] Furthermore, the specific process of sampling delay optimization is as follows: Compare the sampling delay evaluation value with the preset sampling delay threshold obtained from the database; when the sampling delay evaluation value is not greater than the preset sampling delay threshold, no sampling delay optimization is performed, where the preset sampling delay threshold is represented by the average value of the sampling delay evaluation values in the historical time period; when the sampling delay evaluation value is greater than the preset sampling delay threshold, sampling delay optimization is performed; when the monitored drive current is greater than the preset maximum drive current obtained from the database, or the relay voltage is greater than the preset maximum relay voltage obtained from the database, if the sampling delay evaluation value is still greater than the preset sampling delay threshold, sampling times setting is performed; if the sampling delay evaluation value is still greater than the preset sampling delay threshold after sampling times setting, an upper limit alarm is sent to the preset personnel; sampling delay optimization includes drive current setting and relay voltage setting; drive current setting means sending a prompt to the preset personnel to gradually increase the drive current; relay voltage setting means sending a prompt to the preset personnel to gradually increase the voltage of the relay; sampling times setting means sending a prompt to the preset personnel to gradually reduce the sampling times of the photovoltaic signal.

[0062] In this embodiment, when it is monitored that the sampling delay evaluation value is greater than the preset sampling delay threshold, sampling delay optimization is performed: According to the proportional relationship between the sampling delay evaluation value and the preset sampling delay threshold, the drive current is gradually increased in corresponding preset proportions, and the voltage of the relay is gradually increased in corresponding preset proportions; when it is monitored that the drive current is greater than the preset maximum drive current obtained from the database, or the relay voltage is greater than the preset maximum relay voltage obtained from the database, and the sampling delay evaluation value is still greater than the preset sampling delay threshold, a prompt is sent to gradually reduce the sampling times of the photovoltaic signal in corresponding preset proportions; increasing the drive current can improve the response speed of the sampling device, thereby reducing the sampling delay, and increasing the relay voltage can ensure that the relay switches more quickly and reliably, which helps to reduce the sampling delay caused by the relay switching delay. In the case where the drive current and the relay voltage have reached the upper limit, reducing the sampling times can reduce the sampling burden, which helps to alleviate the sampling delay problem, and thus improves the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching.

[0063] Furthermore, the specific process of relay K disconnection delay fault monitoring is as follows: Obtain the relay k delay value, where the relay k delay value is represented by the corresponding duration after disconnecting the relay to be energized; Compare the relay k delay value with the preset delay range obtained from the database, where the preset delay range is preset by the preset personnel; when the relay k delay value is within the preset delay range, it indicates that the relay delay of the corresponding loop is qualified; when the relay k delay value is not within the preset delay range, the corresponding loop is marked as a disconnection delay fault loop, and an alarm prompt is sent to the preset personnel.

[0064] It should be added that after the insulation impedance accuracy monitoring is completed, the insulation impedance fault detection is carried out. The specific process is as follows: Obtain qualified photovoltaic sampling signals, perform numerical conversion based on the qualified photovoltaic sampling signals to obtain the insulation impedance value and save it to the corresponding register; judge whether the loop insulation impedance is normal according to the insulation impedance value; when the insulation impedance value is consistent with the theoretical calculation value, it indicates that the insulation impedance is normal, and send a prompt to allow the loop to start up; when the insulation impedance value is inconsistent with the theoretical calculation value, it indicates that the insulation impedance is abnormal, and send a loop fault prompt and a prompt not to allow the loop to start up; The qualified photovoltaic sampling signals include qualified first sampling signals and qualified second sampling signals; The qualified photovoltaic sampling signals represent the first sampling signal and the second sampling signal corresponding to meeting the qualified photovoltaic conditions; The qualified photovoltaic conditions mean that the relay switching accuracy index is greater than the preset relay switching accuracy threshold, the sampling delay evaluation value is not greater than the preset sampling delay threshold, and at the same time the relay k delay value is within the preset delay range.

[0065] In this embodiment, when it is monitored that the relay k delay value is not within the preset delay range, the corresponding loop is marked as a disconnection delay fault loop, which helps to quickly locate the fault; when a qualified photovoltaic sampling signal is monitored, the insulation impedance value is obtained through numerical conversion by the control chip, which helps to improve the control accuracy of the control chip; judging whether the loop insulation impedance is normal according to the insulation impedance value helps to prevent loop faults or safety hazards caused by insulation faults, and thus improves the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching.

[0066] In summary, by monitoring the volatility of the photovoltaic input voltage when the photovoltaic input loop is connected, then after the monitoring of the volatility of the photovoltaic input voltage is completed, performing insulation impedance accuracy monitoring and judging whether to optimize the insulation impedance accuracy, and finally after the insulation impedance accuracy monitoring is completed, performing insulation impedance fault detection, the stability of the insulation impedance fault detection is improved, and further the signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching is improved, effectively solving the problem of low signal sampling accuracy in the insulation fault diagnosis process of the photovoltaic input loop based on relay switching in the prior art.

[0067] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0068] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one or more of the flows Figure 1 one or more flows and / or blocks Figure 1 or in one or more of the blocks.

[0069] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in one or more of the flows Figure 1 one or more flows and / or blocks Figure 1 or in one or more of the blocks.

[0070] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more of the flows Figure 1 one or more flows and / or blocks Figure 1 or in one or more of the blocks.

[0071] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A photovoltaic input circuit insulation fault diagnosis method based on relay switching, characterized in that: The following steps are involved: S1, when the photovoltaic input loop is connected, the photovoltaic input voltage fluctuation monitoring is performed to determine whether to perform delay matching optimization, the photovoltaic input voltage fluctuation monitoring is used to quantitatively evaluate the impact of the photovoltaic input on the stability of the sampling signal, and the delay matching optimization is used to improve the stability of the sampling signal; S2, after the photovoltaic input voltage fluctuation monitoring is completed, insulation impedance accuracy monitoring is performed to quantitatively evaluate the accuracy of the insulation impedance sampling signal, and determine whether to perform insulation impedance accuracy optimization, wherein the insulation impedance accuracy optimization is used to improve the accuracy of the insulation impedance sampling signal; S3, after the insulation impedance accuracy monitoring is completed, insulation impedance fault detection is performed, and the insulation impedance fault detection is used to determine the working condition of the photovoltaic input circuit.

2. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 1, characterized in that: When the photovoltaic input loop is connected, the photovoltaic input voltage fluctuation is monitored to determine whether to perform delay matching optimization. The specific process is as follows: Monitoring a photovoltaic input voltage fluctuation value, wherein the photovoltaic input voltage fluctuation value represents data reflecting the degree of fluctuation of the photovoltaic input voltage in a preset time period through a difference between a maximum value and a minimum value of the photovoltaic input voltage; When the PV input voltage fluctuation value is not greater than the preset PV voltage fluctuation threshold value obtained from the database, delay matching optimization is not performed and insulation impedance accuracy monitoring continues; When the photovoltaic input voltage fluctuation value is greater than the preset photovoltaic voltage fluctuation threshold obtained from the database, delay matching optimization is performed, wherein the delay matching optimization means sending a prompt to a preset person to gradually increase the stabilization time after the relay is actuated; When the stabilization time after the relay is actuated reaches the preset maximum stabilization time, a circuit cut-off prompt is sent.

3. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 1, characterized in that: After the photovoltaic input voltage fluctuation monitoring is completed, the insulation impedance accuracy monitoring is performed to quantitatively evaluate the accuracy of the insulation impedance sampling signal. The specific process is as follows: Send a prompt to a preset person to obtain a first sampling signal, wherein the first sampling signal represents a signal which is sent to a control chip for sampling and acquisition through an operational amplifier U after a first resistance loop is formed by closing a relay to be closed; Send a prompt to the preset personnel to obtain a second sampling signal, wherein the second sampling signal represents a signal that forms a second resistance loop after passing through the action relay K and is sent to the control chip for sampling and acquisition through the operational amplifier U; The first resistance loop represents a loop including resistors R1, R2, and R3; The second resistance loop refers to a loop including resistors R1 , R3 , and a relay K.

4. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 1, characterized in that: The insulation impedance accuracy monitoring includes relay switching fault monitoring, sampling signal delay fault monitoring and relay K disconnection delay fault monitoring; The insulation impedance accuracy optimization includes relay switching accuracy optimization and sampling delay optimization; The relay switching fault monitoring means combining the acquired relay switching parameters with the preset relay switching parameters to quantitatively evaluate the relay switching accuracy; The sampling signal delay fault monitoring means jointly obtaining the sampling signal delay fault assessment parameter and the preset sampling signal delay fault assessment parameter to quantitatively assess the photovoltaic signal sampling delay situation; The relay switching parameters include relay action time, relay contact resistance final state value, relay pull-in time, and input photovoltaic voltage change rate; The sampling signal delay fault assessment parameters include relay switching delay time, photovoltaic signal sampling times, insulation sampling interval, and ADC conversion time.

5. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 4, characterized in that: The specific process of relay switching fault monitoring is as follows: By analyzing the proportion of the preset relay action time and the relay action time, the relay action time and accuracy reflection value is obtained, which is used to reflect the effect of the relay action time on the relay switching accuracy; By analyzing the proportion of the preset relay contact resistance final state value and the relay contact resistance final state value, the relay contact resistance and accuracy reflection value is obtained, which is used to reflect the effect of the relay contact resistance final state value on the relay switching accuracy; By analyzing the proportion of the preset relay pick-up time and the relay pick-up time, the relay pick-up time and accuracy reflection value is obtained, which is used to reflect the effect of the relay pick-up time on the relay switching accuracy; By analyzing the proportion of the preset input photovoltaic voltage change rate and the input photovoltaic voltage change rate, the photovoltaic voltage change and accuracy reflection value is obtained, which is used to reflect the effect of the input photovoltaic voltage change rate on the relay switching accuracy; After performing weighted calculation on the relay switching data and the corresponding preset relay switching weight, a coupling process is performed to obtain a relay switching accuracy index, which is used to reflect the comprehensive influence of the relay switching parameters and the preset relay switching parameters on the relay switching accuracy; The relay switching data includes relay action time and accuracy reflection value, relay contact resistance and accuracy reflection value, relay pull-in time and accuracy reflection value, photovoltaic voltage change and accuracy reflection value.

6. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 5, characterized in that: The specific process of optimizing the relay switching accuracy is as follows: When the relay switching accuracy index is not greater than the preset relay switching accuracy threshold, the corresponding circuit is marked as a relay switching fault circuit, and the relay switching accuracy is optimized; When the relay switching accuracy index is greater than the preset relay switching accuracy threshold, the relay switching accuracy optimization is not performed; The specific steps of optimizing the relay switching accuracy are as follows: The first step is to set the contact capacitance, wherein the contact capacitance setting means gradually increasing the contact parallel capacitance; The second step is to set the resistance of the sampling input terminal, wherein the resistance of the sampling input terminal is gradually increased in parallel with the sampling input terminal. When the monitored relay switching accuracy index is greater than the preset relay switching accuracy threshold, the relay switching accuracy optimization is stopped, otherwise an alarm is sent to the preset personnel.

7. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 4, characterized in that: The sampling signal delay fault monitoring means performing sampling signal delay analysis on the sampling signal delay fault assessment parameter and the preset sampling signal delay fault assessment parameter; The sampling signal delay analysis includes relay switching delay analysis, photovoltaic signal sampling times delay analysis, insulation sampling interval delay analysis, ADC conversion delay analysis, and comprehensive sampling delay analysis; The relay switching delay analysis indicates that a proportion analysis of the relay switching delay time and the preset relay switching delay time is performed to obtain a relay switching delay reflection value, which is used to reflect the effect of the relay switching delay time on the photovoltaic signal sampling delay. The photovoltaic signal sampling times delay analysis means analyzing the proportion of the photovoltaic signal sampling times and the preset photovoltaic signal sampling times to obtain a photovoltaic signal sampling times reflection value, which is used to reflect the effect of the photovoltaic signal sampling times on the photovoltaic signal sampling delay; The insulation sampling interval delay analysis means analyzing the proportion of the preset insulation sampling interval and the insulation sampling interval to obtain an insulation sampling interval reflection value, which is used to reflect the effect of the insulation sampling interval on the photovoltaic signal sampling delay; The ADC conversion delay analysis means analyzing the proportion of the ADC conversion time and the preset ADC conversion time to obtain an ADC conversion time reflection value, which is used to reflect the effect of the ADC conversion time on the photovoltaic signal sampling delay; The comprehensive sampling delay analysis means that after weighted operation is performed on the sampling signal delay data, the relay switching accuracy index and the corresponding preset sampling signal delay weight, a coupling process is performed to obtain a sampling delay evaluation value, and the sampling delay evaluation value is used to reflect the comprehensive effect of the sampling signal delay fault evaluation parameter and the preset sampling signal delay fault evaluation parameter on the photovoltaic signal sampling delay situation; The sampling signal delay data includes a relay switching delay reflection value, a photovoltaic signal sampling times reflection value, an insulation sampling interval reflection value, an ADC conversion time reflection value, and a relay switching accuracy index.

8. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 7, characterized in that: The specific process of sampling delay optimization is as follows: When the sampling delay evaluation value is not greater than the preset sampling delay threshold, sampling delay optimization is not performed; When the sampling delay evaluation value is greater than a preset sampling delay threshold, sampling delay optimization is performed; When the monitored drive current is greater than the preset maximum drive current obtained from the database, or the relay voltage is greater than the preset maximum relay voltage obtained from the database, if the sampling delay evaluation value is still greater than the preset sampling delay threshold, the sampling times are set; If the sampling delay evaluation value is still greater than the preset sampling delay threshold after the sampling times are set, an upper limit alarm is sent to the preset personnel; The sampling delay optimization includes drive current setting and relay voltage setting; The drive current setting means sending a prompt to a preset person to increase the drive current step by step; The relay voltage setting means sending a prompt to a preset person to increase the voltage of the relay step by step; The sampling times setting means sending a prompt to a preset person to gradually reduce the sampling times of the photovoltaic signal.

9. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 4, characterized in that: The specific process of relay K disconnection delay fault monitoring is as follows: Obtaining a delay value of relay k, wherein the delay value of relay k is represented by a delay time corresponding to the time after disconnecting the relay to be attracted; Compare the delay value of relay k with the preset delay range obtained from the database; When the delay value of relay k is within the preset delay range, it indicates that the relay delay of the corresponding circuit is qualified; When the delay value of relay k is not within the preset delay range, the corresponding circuit will be marked as a disconnect delay fault circuit and an alarm will be sent to the preset personnel.

10. A photovoltaic input circuit insulation fault diagnosis method based on relay switching as claimed in claim 1, characterized in that: After the insulation impedance accuracy monitoring is completed, insulation impedance fault detection is performed, and the specific process is as follows: Obtain a qualified photovoltaic sampling signal, perform numerical conversion based on the qualified photovoltaic sampling signal to obtain an insulation impedance value and save it in a corresponding register; When the insulation impedance value is consistent with the theoretical calculated value, it indicates that the insulation impedance is normal, and a prompt is sent to allow the circuit to start; When the insulation impedance value is inconsistent with the theoretical calculated value, it indicates that the insulation impedance is abnormal, and a loop fault prompt and a loop startup prompt are sent; The qualified photovoltaic sampling signal includes a qualified first sampling signal and a qualified second sampling signal; The qualified photovoltaic sampling signal represents a first sampling signal and a second sampling signal corresponding to a qualified photovoltaic condition; The qualified photovoltaic condition indicates that the relay switching accuracy index is greater than a preset relay switching accuracy threshold, the sampling delay evaluation value is not greater than a preset sampling delay threshold, and the relay k delay value is within a preset delay range.

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