Direct current charging pile insulation monitoring method and system

Abstract

The invention relates to the technical field of power electronics, in particular to a direct-current charging pile insulation monitoring method and system, and the method comprises the following steps: monitoring the voltage deviation between a branch and a bus in real time, adjusting a measurement compensation parameter, correcting a branch insulation resistance measurement value, recognizing leakage current drift, positioning a leakage branch, triggering relay control, and sending alarm information. And generating a charging pile monitoring record. According to the method, the branch voltage deviation trend and the voltage compensation parameters are combined, the branch voltage measurement consistency is improved, the insulation resistance fluctuation is utilized to compare and correct the observation error, the measurement precision is optimized, the current deviation compensation in the no-load state is adopted to eliminate the zero drift interference of the sensor, and the measurement accuracy is improved. A current jump amplitude and a voltage direction are combined to identify an electric leakage branch, positioning accuracy is enhanced, a relay control and event information linkage mode is used, alarm response and equipment state records form a closed loop, and real-time performance and integrity of system monitoring are improved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and particularly to a method and system for monitoring the insulation of a DC charging pile. Background Art

[0002] The field of power electronics technology includes aspects such as power conversion, power control, and the safe operation of electrical equipment. It is one of the core branches of modern electrical engineering and automation systems. This technical field mainly focuses on achieving efficient power transmission, conversion, monitoring, and protection. It is widely used in electric vehicle charging facilities, photovoltaic power generation systems, energy storage systems, rail transit, and industrial automation scenarios. In a DC power supply system, under a DC floating ground structure, continuous monitoring of the system's insulation performance to the ground becomes an important part of ensuring personal safety and the stable operation of the system. The insulation monitoring branch in power electronics technology focuses on solving problems such as the formation of leakage channels to the ground during equipment operation, early warning of electrical faults, and linkage of monitoring and communication. The core technologies include modules such as bridge method measurement, voltage sampling, leakage current induction, adaptive capacitance compensation, and data remote communication, and real-time data interaction and remote control are achieved through industrial protocols such as RS485.

[0003] Among them, a method for monitoring the insulation of a DC charging pile refers to a monitoring method for real-time monitoring of the insulation resistance of the DC bus and related branches inside the DC charging pile and providing alarm and remote control functions. The specific technical matters cover the real-time measurement and identification of the insulation resistance of the DC bus and each branch of the charging pile. The method uses an unbalanced bridge circuit or a balanced bridge circuit method, through the periodic switching of the bridge resistors inside the module and the control of the grounding switch, in cooperation with a leakage current sensor or a shunt to achieve the sampling of current and voltage signals, and triggers the relay output to achieve an alarm by setting an alarm threshold, and realizes remote start / stop control and remote monitoring parameter setting through a communication interface.

[0004] Traditional DC charging pile insulation monitoring technologies rely mostly on static bridge structures or single-cycle sampling in the measurement of voltage and insulation resistance, lacking a judgment mechanism based on the change trend of the difference within the time series, and unable to dynamically identify and finely adjust branch offsets. In the measurement of leakage current, the zero drift problem of the sensor signal in the no-load stage is not fully considered, which is prone to false judgment or missed judgment, and there is also a lack of a branch identification mechanism for multi-parameter synchronous linkage of current and voltage, resulting in limited accuracy of leakage judgment. In relay control and information reporting, it only stays at the alarm threshold trigger logic, lacking the ability to bind with specific device numbers and location information, making it difficult to achieve device-level traceability and behavior recording. In complex working conditions with multiple branches, problems such as delayed identification of leakage events or inaccurate matching of alarm information often occur, affecting the system operation efficiency and maintenance response ability. Summary of the Invention

[0005] To solve the technical problems existing in the prior art, an embodiment of the present invention provides a method and system for insulating monitoring of a DC charging pile. The technical solution is as follows:

[0006] To achieve the above object, the present invention adopts the following technical solution. A method for insulating monitoring of a DC charging pile includes the following steps:

[0007] S1: Real-time monitor the voltage value of each branch and the bus voltage value in the DC charging pile, analyze the offset direction and offset amplitude of each branch in a continuous operation cycle, and combine the voltage change trend of the branch to adjust the measurement compensation parameter of the branch to obtain the calibrated compensation value of the branch voltage.

[0008] S2: Call the calibrated compensation value of the branch voltage, real-time obtain the observed value of the insulation resistance of the branch and compare it with the set standard threshold of the insulation resistance. Combine the observed fluctuation degree of the branch in the execution sequence, compare the fluctuation degree of the measured value of the resistance value of each branch, and correct the observed value of the target branch to generate the corrected value of the insulation resistance.

[0009] S3: Based on the corrected value of the insulation resistance, extract the drift direction and offset amplitude in the continuous static sampling of each channel according to the multi-group leakage current channel sampling values of the charging pile in the no-load operation state, calculate the current sampling compensation parameter, and obtain the static drift compensation value.

[0010] S4: Call the static drift compensation value, real-time monitor the corrected current signal, detect abnormal data, identify the leakage event, and identify the leakage branch by extracting the current jump amplitude of each branch and the change direction of the voltage to the ground, and obtain the branch positioning determination result.

[0011] As a further solution of the present invention, the calibrated compensation value of the branch voltage includes the branch voltage offset amplitude, voltage change direction, and measurement compensation parameter. The corrected value of the insulation resistance includes the resistance measurement deviation amplitude, resistance value fluctuation trend, and comparison correction factor. The static drift compensation value includes the offset channel number, offset amplitude parameter, and zero-current difference coefficient. The branch positioning determination result is specifically the leakage branch number, current mutation amplitude, and voltage change direction.

[0012] As a further solution of the present invention, the step of real-time monitoring the voltage value of each branch and the bus voltage value in the DC charging pile, analyzing the offset direction and offset amplitude of each branch in a continuous operation cycle, and combining the voltage change trend of the branch to adjust the measurement compensation parameter of the branch to obtain the calibrated compensation value of the branch voltage is specifically as follows:

[0013] S101: Monitor the voltage values of each branch and the bus voltage in the DC charging pile in real time, compare the voltage values of each branch with the bus voltage value, extract voltage offset data, and classify and number the offset data sequences of each branch to obtain the branch voltage difference sequence value;

[0014] S102: Based on the branch voltage difference sequence value, analyze the offset direction and offset amplitude of each branch in the continuous operation cycle, evaluate the change of voltage offset in multiple samplings, and obtain the branch voltage offset trend data;

[0015] S103: Call the branch voltage offset trend data, and adjust the measurement compensation parameters in the voltage sampling channel according to the voltage offset direction and offset amplitude of each branch to obtain the branch voltage calibration compensation value.

[0016] As a further solution of the present invention, the steps of calling the branch voltage calibration compensation value, obtaining the insulation resistance observation value of the branch in real time and comparing it with the set insulation resistance standard threshold, combining the observed fluctuation degree of the branch in the execution sequence, comparing the fluctuation degree of the measured value of the resistance of each branch, and correcting the observation value of the target branch to generate the insulation resistance correction value are specifically as follows:

[0017] S201: Call the branch voltage calibration compensation value, obtain the insulation resistance observation value of each branch in real time, combine the preset insulation resistance standard threshold, analyze the deviation of the branch in the current cycle by calculating the difference between the observation value and the standard threshold of each branch, and obtain the insulation resistance difference data;

[0018] S202: Based on the insulation resistance difference data, collect the continuous observation values of each branch in the execution sequence, calculate the observation value fluctuation amplitude of each branch, and obtain the branch fluctuation characteristic information;

[0019] S203: Call the branch fluctuation characteristic information, extract the branch with the smallest fluctuation amplitude as the correction reference set by comparing the fluctuation degree of the measured value of the resistance of each branch, construct the observation value correction baseline, and perform offset correction on the insulation resistance observation value of the target branch to obtain the insulation resistance correction value.

[0020] As a further solution of the present invention, the specific formula for calculating the observation value fluctuation amplitude of each branch is:

[0021]

[0022] Calculate the fluctuation intensity of the branch resistance observation value;

[0023] Among them, F i′ represents the fluctuation intensity of the resistance observation value of branch i′, R i′,m′Denote the observed insulation resistance value of branch i' at the m'-th sampling moment. Denote the average observed insulation resistance value of branch i' over the entire cycle, R i′,max Denote the maximum observed value of branch i' within the cycle, R i′,min Denote the minimum observed value of branch i' within the cycle, n' denote the total number of sampling times within the cycle of branch i', i' denote the number of the branch being currently analyzed, and m' denote the sampling point number within the branch.

[0024] As a further solution of the present invention, based on the insulation resistance correction value, according to multiple groups of leakage current channel sampling values of the charging pile in the no-load operation state, extract the drift direction and offset amplitude in the continuous static sampling of each channel, and the steps of calculating the current sampling compensation parameter and obtaining the static drift compensation value are specifically as follows:

[0025] S301: Based on the insulation resistance correction value, collect the continuous static current sampling values of multiple leakage current channels of the charging pile in the no-load operation state, extract the direction change and offset amplitude in the sampling sequence of each channel, and obtain the leakage channel offset characteristic information;

[0026] S302: Call the leakage channel offset characteristic information, and according to the deviation between the static sampling value of each channel and the preset zero-current reference value, identify the offset channels to obtain the channel drift identification result;

[0027] S303: According to the channel drift identification result, extract the sampling offset amount of the offset channels, and combine the sampling direction change trend to calculate the current sampling compensation parameter and generate the static drift compensation value.

[0028] As a further solution of the present invention, call the static drift compensation value, monitor the corrected current signal in real time, detect abnormal data, identify leakage events, and the steps of identifying the leakage branch and obtaining the branch positioning determination result by extracting the current jump amplitude and the change direction of the ground voltage of each branch are specifically as follows:

[0029] S401: Call the static drift compensation value, detect abnormal data by monitoring the corrected current signal in real time, extract the jump point signal in the current signal, and obtain the jump signal identification result;

[0030] The specific formula for extracting the jump point signal in the current signal is:

[0031]

[0032] Calculate the jump amplitude value;

[0033] Among them, represents the corrected jump amplitude value of the k'-th point in channel j', I k′represents the leakage current value of the k'-th sampling point in channel j', I k′-1 represents the leakage current value of the (k'-1)-th sampling point in channel j', Δt represents the sampling time interval between two adjacent sampling points, I avg，j′ represents the average value of the current values of all sampling points in channel j' during the current detection period, I max,j′ represents the maximum current value in channel j' during the current period, I min,j′ represents the minimum current value in channel j' during the current period, k' represents the serial number of the k'-th sampling point for jump change recognition in the current channel, j' represents the serial number of the leakage current detection channel currently being analyzed;

[0034] S402: Based on the jump signal recognition result, collect the ground voltage data of each branch during the corresponding time period, classify the voltage fluctuation direction, analyze the time matching situation between the voltage change direction and the jump current, and obtain the voltage direction linkage eigenvalue;

[0035] S403: According to the voltage direction linkage eigenvalue and the matching degree, identify the leakage branch and generate the branch positioning determination result.

[0036] As a further solution of the present invention, the method further includes:

[0037] S5: Based on the branch positioning determination result, according to the leakage branch number, send a closing control command to the relay configured for the leakage branch, and real-time monitor the closing feedback status signal. Combine the time of the leakage event, the number and location of the charging pile, match the alarm information and send it to obtain the charging pile monitoring record;

[0038] The charging pile monitoring record specifically refers to the closing control signal, the alarm matching information, and the leakage event processing record.

[0039] As a further solution of the present invention, the step of, based on the branch positioning determination result, according to the leakage branch number, sending a closing control command to the relay configured for the leakage branch, and real-time monitoring the closing feedback status signal, combining the time of the leakage event, the number and location of the charging pile, matching the alarm information and sending it to obtain the charging pile monitoring record is specifically as follows:

[0040] S501: Based on the branch positioning determination result, according to the number of the leakage branch, locate the target relay control unit, send a closing control instruction to the relay, real-time monitor the closing state feedback signal of the relay, and obtain the relay closing response information;

[0041] S502: Invoke the relay closing response information, combine the time node of the leakage event and the branch number information, extract the device number and physical installation location of the current charging pile, and construct the leakage event information set;

[0042] S503: According to the leakage event information set, the alarm information is matched and sent to the management personnel to generate a charging pile monitoring record.

[0043] On the other hand, a DC charging pile insulation monitoring system is provided, which is applied to a DC charging pile insulation monitoring method, and the system includes:

[0044] The voltage offset calibration module monitors the voltage value of each branch and the bus voltage value in the DC charging pile in real time, extracts the voltage difference between each branch and the bus, and adjusts the measurement compensation parameters according to the voltage offset direction and change amplitude of each branch in continuous sampling to obtain the branch voltage calibration compensation value;

[0045] The insulation resistance correction module collects the insulation resistance observation value of each branch cycle in real time based on the branch voltage calibration compensation value, compares it with the set insulation resistance standard threshold, and combines the fluctuation of each branch to build a correction reference baseline, offset adjust the observation value, and generate an insulation resistance correction value;

[0046] The leakage drift compensation module collects the static current sampling sequence of each channel under no-load state based on the insulation resistance correction value, analyzes the offset amplitude and direction of the sampling data, identifies the offset channel and adjusts the compensation parameters to obtain the static drift compensation value;

[0047] The fault branch identification module obtains the corrected real-time current data based on the static drift compensation value, extracts the jump current amplitude of each branch, and simultaneously obtains the direction of voltage change to ground within the jump period, identifies the leakage branch according to the linkage characteristics of current and voltage changes, and obtains the branch location determination result;

[0048] The linkage control recording module identifies the leakage branch number based on the branch positioning judgment result, locates the relay control unit and sends a closing command, collects the relay feedback signal status, combines the event time, equipment number, and physical location, matches the alarm content and sends it, and establishes the charging pile monitoring record.

[0049] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0050] By combining the branch voltage offset trend with the voltage compensation parameters, the consistency of branch voltage measurement is improved. The observation error is corrected by comparing the insulation resistance fluctuations and the measurement accuracy is optimized. The current offset compensation under no-load state is used to eliminate the interference of sensor zero drift. The leakage branch is identified by combining the current jump amplitude and voltage direction to enhance positioning accuracy. The relay control and event information linkage method is used to form a closed loop between the alarm response and the equipment status record, thereby improving the real-time and integrity of system monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0052] Figure 1 It is a schematic diagram of the working process of the present invention;

[0053] Figure 2 It is a system flow chart of the present invention. Specific embodiments

[0054] The following will describe the technical solutions in the present invention in conjunction with the accompanying drawings.

[0055] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "example" in the present invention should not be construed as more preferred or more advantageous than other embodiments or design solutions. Exactly speaking, the use of the word "example" is intended to present concepts in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or either of them can be selected.

[0056] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when their differences are not emphasized, the meanings they express are the same. "(of)", "corresponding", and "corresponding" can sometimes be used interchangeably. It should be noted that when their differences are not emphasized, the meanings they express are the same.

[0057] In the embodiments of the present invention, sometimes subscripts such as W1 may be written in a non-subscript form such as W1. When their differences are not emphasized, the meanings they express are the same.

[0058] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail in conjunction with the accompanying drawings and specific embodiments.

[0059] Please refer to Figure 1 , the present invention provides a technical solution, a method for insulating monitoring of a DC charging pile, including the following steps:

[0060] S1: Real-time monitor the voltage value of each branch and the bus voltage value in the DC charging pile, analyze the offset direction and offset amplitude of each branch within a continuous operation cycle, and combine the voltage change trend of the branch to adjust the measurement compensation parameter of the branch to obtain the calibrated compensation value of the branch voltage;

[0061] S2: Call the branch voltage calibration compensation value, obtain the observed insulation resistance value of the branch in real time, compare it with the set insulation resistance standard threshold, combine the observed fluctuation degree of the branch in the execution sequence, compare the fluctuation degree of the measured resistance value of each branch, correct the observed value of the target branch, and generate an insulation resistance correction value;

[0062] S3: Based on the insulation resistance correction value, according to multiple groups of leakage current channel sampling values of the charging pile in the no-load operation state, extract the drift direction and offset amplitude in the continuous static sampling of each channel, calculate the current sampling compensation parameter, and obtain the static drift compensation value;

[0063] S4: Call the static drift compensation value, monitor the corrected current signal in real time, detect abnormal data, identify leakage events, identify the leakage branch by extracting the current jump amplitude of each branch and the change direction of the ground voltage, and obtain the branch positioning determination result;

[0064] S5: Based on the branch positioning determination result, according to the leakage branch number, send a closing control command to the relay configured for the leakage branch, and monitor the closing feedback status signal in real time. Combine the time of the leakage event, the number and location of the charging pile, match the alarm information and send it to obtain the charging pile monitoring record;

[0065] The branch voltage calibration compensation value includes the branch voltage offset amplitude, voltage change direction, and measurement compensation parameter. The insulation resistance correction value includes the resistance measurement deviation amplitude, resistance value fluctuation trend, and comparison correction factor. The static drift compensation value includes the offset channel number, offset amplitude parameter, and zero current difference coefficient. The branch positioning determination result is specifically the leakage branch number, current mutation amplitude, and voltage change direction. The charging pile monitoring record specifically refers to the closing control signal, alarm matching information, and leakage event processing record.

[0066] The steps of real-time monitoring the voltage value of each branch and the bus voltage value in the DC charging pile, analyzing the offset direction and offset amplitude of each branch in the continuous operation cycle, and adjusting the measurement compensation parameter of the branch to obtain the branch voltage calibration compensation value are specifically as follows:

[0067] S101: Real-time monitor the voltage value of each branch and the bus voltage value in the DC charging pile, compare the voltage value of each branch with the bus voltage value, extract the voltage offset data, and classify and number the offset data sequence of each branch to obtain the branch voltage difference sequence value;

[0068] In the voltage difference extraction sub-module, first, the real-time voltage sampling signals of each branch of the DC charging pile are paired and compared with the bus voltage to construct the offset relationship of the branch relative to the bus, and the differences are extracted in sequence according to the channel number to form an ordered number sequence. The sampling period is 10 ms, and all sampling data are archived according to time tags to identify the voltage fluctuation changes of the branch during the operation period. The voltage offset calculation is performed based on the sampling data at the same time point. After the operation, the results enter the difference buffer area, and continuous sequence identification and number registration are carried out. The formula is:

[0069] ΔV i =V i -V b ;

[0070] Where, ΔV i is the voltage offset value of branch i, V i is the voltage sampling value of branch i at the current moment, and V b is the voltage sampling value of the bus at this moment.

[0071] Set V i =422.5V, V b =420.0V, then substitute into the calculation:

[0072] ΔV i =422.5 - 420.0=2.5V;

[0073] The calculation results show that the instantaneous offset value of the branch voltage relative to the bus voltage is 2.5V. The offset value is recorded in the branch numbered CH05. This value is continuously recorded and used as the basis for subsequent offset trend judgment. If the offset values of this branch remain in the same offset direction and are stable in value in multiple adjacent cycles, it is classified as an offset trend branch and enters the numbered sequence grouping, forming a comparison interval with other branches and preparing for trend calculation.

[0074] S102: Based on the branch voltage difference sequence values, analyze the offset direction and offset amplitude of each branch in consecutive operation cycles, evaluate the changes in voltage offset during multiple samplings, and obtain the branch voltage offset trend data;

[0075] After obtaining the difference sequence, the offset trend analysis sub-module performs trend analysis according to the sampling time sequence, judges the voltage offset direction and change amplitude. The direction judgment is based on the comparison result of the current sampling value and the previous sampling value. At the same time, the extreme value and the occurrence time are recorded to construct the change trajectory within the time span. When analyzing the trend, normalization calculation is performed using the offset amplitude and the sampling duration to extract the voltage change rate as the branch voltage stability evaluation parameter. The formula is:

[0076]

[0077] Among them, R i is the voltage change rate of branch i, ΔV max,i is its maximum offset value, ΔV min,i is the minimum offset value, T i is the duration of this change process.

[0078] Set ΔV max,i = 3.4V, ΔV min,i = 1.6V, T i = 0.1s, substitute into the calculation:

[0079]

[0080] The calculation results show that the voltage offset change rate of this branch is relatively high in a short period of time. This result can be used in the subsequent compensation judgment logic to distinguish high-frequency offset branches from stable branches. The system marks such branches with a high change rate as potential unstable paths, and at the same time records its trend as a positive growth and enters the offset trend list.

[0081] S103: Call the branch voltage offset trend data, and adjust the measurement compensation parameters in the voltage sampling channel according to the voltage offset direction and offset amplitude of each branch to obtain the branch voltage calibration compensation value;

[0082] The voltage compensation parameter adjustment sub-module extracts the branch change characteristics based on the offset trend data. By comparing the change direction and the interval to which the change rate belongs, the corresponding adjustment factor is matched. The adjustment parameter is written into the channel configuration table as the sampling channel gain or the hardware compensation configuration item. Before the operation, it is necessary to verify that the number of the branch corresponding to the current channel is consistent with its trend type to avoid incorrect adjustment across branches. The parameter adjustment is executed in the form of directly adding the adjustment factor to the current compensation value, using the formula:

[0083] C i ′ = C i + α i ;

[0084] Among them, C i ′ is the adjusted compensation value of branch i, C i is the original compensation value, α i is the adjustment factor, and the adjustment factor is determined by the interval where the offset trend is located.

[0085] Set C i = 0.015, α i = -0.01, substitute into the calculation:

[0086] C i ′ = 0.015 - 0.01 = 0.005;

[0087] The calculation results show that the compensation coefficient needs to be reduced for the current branch in the state of strong positive offset to lower the voltage input offset. The correction value will be directly written into the channel register. Once this operation is completed, it will immediately affect the subsequent voltage sampling values. During continuous sampling periods, verify whether the change trend of the sampling values converges. If the offset direction changes or the offset rate slows down, it is considered that the compensation takes effect; otherwise, enter the next round of correction parameter evaluation process.

[0088] Call the branch voltage calibration compensation value, obtain the observed insulation resistance value of the branch in real time and compare it with the set insulation resistance standard threshold. Combine the observed fluctuation degree of the branch in the execution sequence, compare the fluctuation degree of the measured resistance value of each branch, and correct the observed value of the target branch to generate the insulation resistance correction value. The specific steps are as follows:

[0089] S201: Call the branch voltage calibration compensation value, obtain the observed insulation resistance value of each branch in real time. Combine the preset insulation resistance standard threshold, analyze the deviation of the branch in the current cycle by calculating the difference between the observed value and the standard threshold of each branch, and obtain the insulation resistance difference data.

[0090] To call the branch voltage calibration compensation value, first extract the compensation factor of each branch in the current cycle from the compensation data table and apply it to the branch voltage signal correction path. Input the compensated branch signal into the insulation resistance measurement module to obtain the resistance observed value in real time. During the process of obtaining the observed value, set the insulation resistance observation period to 500 ms and the sampling interval to 20 ms to form a complete observation sequence. During this process, call the preset insulation resistance standard threshold to compare the real-time observed values of each branch. This threshold is set by the manufacturer, and the setting value source is that in the normal floating ground operation of the DC charging pile system, the ground resistance of each branch is required to be not less than 2 MΩ, and the set threshold is 2.5 MΩ as the lower limit reference value. The system calculates the difference between the observed value of each branch and this standard threshold using the following formula:

[0091] D i =R i -R s ;

[0092] Where, D i is the insulation resistance deviation value of branch i, R i is the observed insulation resistance value of branch i, and R s is the standard insulation resistance threshold. Set R i =2.1 MΩ, R s =2.5 MΩ, and substitute into the calculation:

[0093] D i =2.1 - 2.5=-0.4 MΩ;

[0094] This result indicates that the insulation resistance of this branch is lower than the threshold of 0.4 MΩ. This deviation value will be used as the basis for subsequent error correction judgment and recorded under the branch number information in the current monitoring period. The deviation value of each branch is represented by a negative value for being lower than the standard and a positive value for being higher than the standard. Finally, a deviation list is formed in the dataset, and this list will be transmitted to the fluctuation analysis module for change trend identification, and finally the insulation resistance difference data is output.

[0095] S202: Based on the insulation resistance difference data, collect the continuous observation values of each branch within the execution sequence, calculate the fluctuation amplitude of the observation values of each branch, and obtain the branch fluctuation characteristic information;

[0096] The specific formula for calculating the fluctuation amplitude of the observation values of each branch is:

[0097]

[0098] Calculate the fluctuation intensity of the branch resistance observation value;

[0099] Among them, F i′ represents the fluctuation intensity of the resistance observation value of branch i′, R i′,m′ represents the insulation resistance observation value of branch i′ at the m′-th sampling moment, represents the average insulation resistance observation value of branch i′ within the full cycle, R i′,max represents the maximum observation value of branch i′ within the cycle, R i′,min represents the minimum observation value of branch i′ within the cycle, n′ represents the total number of samplings of branch i′ within the cycle, i′ represents the current analyzed branch number, and m′ represents the sampling point number within the branch.

[0100] Formula:

[0101]

[0102] Detailed explanation of the formula and the derivation process of the formula calculation:

[0103] The formula is used to calculate the insulation resistance fluctuation intensity value of each branch within a certain observation sequence, and the result is used to describe the stability of the branch resistance measurement value in the time series and is used for extracting the branch fluctuation characteristic information;

[0104] Parameter meanings and set values:

[0105] F i′ is the resistance fluctuation intensity value of branch i′;

[0106] n′ is the total number of samplings within the cycle. It is set that the insulation monitoring module samples once every 10 ms and the cycle is 200 ms, then n′ = 20;

[0107] R i′,m′is the resistance observation value of the i'-th branch at the m'-th moment. The obtained continuous observation values are set as follows: [1980, 2020, 2010, 2000, 1990, 2005, 2015, 2008, 1985, 1998, 2002, 2007, 2012, 1988, 1995, 1999, 2004, 2010, 2000, 2003], with the unit of kΩ, R i′,max = 2020, R i′,min = 1980;

[0108] is the mean value of this sequence,

[0109] Substitute the parameters into the formula for calculation:

[0110]

[0111] F i′ = 12.52 + 0.02002 = 12.54002;

[0112] The result 12.54002 indicates that there are fluctuations with a moderate amplitude in the observed data of the branch resistance within the period. This value will be used as the basis for judging the stability of the branch resistance and for the next step of corrected baseline screening and deviation tolerance judgment.

[0113] S203: Invoke the branch fluctuation characteristic information. By comparing the fluctuation degrees of the measured values of the resistance of each branch, extract the branch with the smallest fluctuation amplitude as the corrected reference set, construct the observed value corrected baseline, and perform offset correction on the insulation resistance observed value of the target branch to obtain the insulation resistance corrected value;

[0114] Invoke the branch fluctuation characteristic information. The system sorts according to the fluctuation amplitudes of all branches, selects the top 3 branches with the smallest fluctuation amplitudes to form the corrected reference set, and performs weighted average processing on the observed values of this set to construct the reference corrected baseline, and perform offset correction processing on the current observed value of the target branch. The correction formula is as follows:

[0115] R i ' = R i + β · (R r - R i );

[0116] Among them, R i ' is the corrected resistance value of the target branch, R i is the original observed value, R r is the reference baseline value, and β is the correction coefficient.

[0117] Set R i = 2.0 MΩ, R r= 2.4 MΩ, β = 0.5, substitute into the calculation:

[0118] R i ′ = 2.0 + 0.5·(2.4 - 2.0) = 2.0 + 0.2 = 2.2 MΩ;

[0119] This result indicates that the observed value of the target branch resistance is increased by 0.2 MΩ. After the correction action is completed, the system records both the corrected value and the original value for subsequent evaluation of the offset trend convergence. This corrected value is also used as a reference for judging anomalies and alarms in the current cycle, and finally the corrected value of the insulation resistance is obtained.

[0120] Based on the corrected value of the insulation resistance, according to the multi-group leakage current channel sampling values of the charging pile in the no-load operation state, extract the drift direction and offset amplitude in the continuous static sampling of each channel, and calculate the current sampling compensation parameter to obtain the static drift compensation value. The specific steps are as follows:

[0121] S301: Based on the corrected value of the insulation resistance, collect the continuous static current sampling values of multiple leakage current channels of the charging pile in the no-load operation state, extract the direction change and offset amplitude in the sampling sequence of each channel, and obtain the leakage channel offset characteristic information;

[0122] Based on the corrected value of the insulation resistance, when the charging pile is in the no-load operation state, call the static sampling channels of each channel, perform continuous multi-cycle data acquisition on all leakage current sensors, set the single-cycle sampling time to 200 ms, the number of cycles to 10, and store the sampling data corresponding to each channel in an independent buffer. The buffer structure establishes a sequence indexed by time. During the extraction process, take out the sampling value sequence of each cycle from each channel, construct the static section current change trajectory, judge the change direction between adjacent two points in the sequence, perform subtraction operation on each group of sampling point pairs and record their positive and negative values. A positive value represents the offset direction to the positive, and a negative value represents the offset direction to the negative. Count the number of consecutive points with the same direction as the basis for judging the direction change trend. At the same time, take the difference between the maximum value and the minimum value in each channel sequence as the offset amplitude, and use the following formula to calculate the offset amplitude:

[0123] F j = I max,j - I min,j ;

[0124] Among them, F j is the static offset amplitude of the jth channel, I max,j is the maximum current value in the sampling sequence of this channel, and I min,j is the minimum current value.

[0125] Set the sampling value sequence of the 5th channel as: 0.02 A, 0.03 A, 0.025 A, 0.04 A, 0.035 A, then:

[0126] F5 = 0.04 - 0.02 = 0.02 A;

[0127] Pack the offset direction trend value and the offset amplitude value and write them into the channel status cache, and mark its channel number. Finally, form a multi-dimensional feature information record set including the channel number, offset direction trend, and maximum amplitude value, and output the leakage channel offset feature information.

[0128] S302: Call the leakage channel offset feature information, identify the offset channels according to the deviation between the static sampling value of each channel and the preset zero-current reference value, and obtain the channel drift identification result;

[0129] Call the leakage channel offset feature information, judge the difference between the maximum offset value and the preset zero-current reference value in the sampling sequence of each channel. The preset zero-current reference value is derived from the static output mean value of the sensor under no-load conditions. The system sets the static zero reference to 0.005 A, the channel judgment threshold is set to ±0.01 A, the system calculates the difference between the offset amplitude value of each channel and the zero reference, and compares it with the offset judgment threshold. Use the following formula:

[0130] D j = |F j - I0|;

[0131] Where, D j is the offset judgment value of channel j, F j is the offset amplitude of the channel, and I0 is the preset static zero-current reference value.

[0132] Assume that the offset amplitude of channel 4 is 0.018 A and the reference value is 0.005 A, then:

[0133] D4 = |0.018 - 0.005| = 0.013 A;

[0134] This result exceeds the offset judgment threshold of 0.01 A. The system determines that channel 4 is a channel with static offset, records this judgment result and adds the channel number and judgment time label. At the same time, classify all channel numbers that meet the conditions into the offset channel set, which is used as the input for subsequent compensation processing. Finally, obtain the channel drift identification result.

[0135] S303: According to the channel drift identification result, extract the sampling offset of the offset channel, combine it with the sampling direction change trend, calculate the current sampling compensation parameter, and generate the static drift compensation value;

[0136] According to the channel drift identification result, the system extracts the sampling offset value and the corresponding sampling direction change trend of the identified offset channels, and uses them as the compensation adjustment reference parameters. In the compensation parameter calculation, set the direction factor s according to the offset direction trendj If the channel trend is a positive offset, then s j = -1; if it is a negative offset, then s j = +1. The following formula is used to calculate the current compensation value:

[0137] C j = s j ·γ·F j ;

[0138] Where C j is the static compensation value of channel j, s j is the direction factor, γ is the proportionality coefficient with a set value of 0.8, and F j is the offset amplitude.

[0139] Assume that there is a negative offset in channel CH02 with an offset amplitude of 0.015 A. Then s2 = +1. Substitute it into the calculation:

[0140] C2 = 1·0.8·0.015 = 0.012 A;

[0141] After calculation, it is obtained that the compensation value of 0.012 A should be subtracted from this channel during the sampling process. The system writes this value into the channel compensation parameter table, binds the current channel address and the parameter effective time, and automatically loads it in the next sampling cycle, records all compensation parameters and outputs the static drift compensation value.

[0142] Call the static drift compensation value, monitor the corrected current signal in real time, detect abnormal data, identify leakage events. The steps to identify the leakage branch and obtain the branch positioning determination result by extracting the current jump amplitude and the change direction of the ground voltage of each branch are as follows:

[0143] S401: Call the static drift compensation value, detect abnormal data by monitoring the corrected current signal in real time, extract the jump point signal in the current signal, and obtain the jump signal recognition result;

[0144] The specific formula for extracting the jump point signal in the current signal is:

[0145]

[0146] Calculate the jump amplitude value;

[0147] Where represents the corrected jump amplitude value of the k'-th point in channel j', I k′ represents the leakage current value of the k'-th sampling point in channel j', I k′-1 represents the leakage current value of the (k'-1)-th sampling point in channel j', Δt represents the sampling time interval between two adjacent sampling points, I avg,j′represents the average value of the current values at all sampling points of channel j' during the current detection period, I max,j′ represents the maximum current value of channel j' during the current period, I min,j′ represents the minimum current value of channel j' during the current period, k' represents the serial number of the k'-th sampling point used for jump identification in the current channel, and j' represents the serial number of the leakage current detection channel currently being analyzed;

[0148] Formula:

[0149]

[0150] Detailed explanation of the formula and the derivation process of formula calculation:

[0151] The formula is used to calculate the corrected jump amplitude value, identify the mutation points in the leakage current signal and evaluate the jump intensity, and the result is used to generate the jump signal identification result;

[0152] Meaning of parameters and set values:

[0153] I k′ is the current value of the k'-th sampling point in channel j', the sampling period is set to 1 ms, and the value is 0.085 A;

[0154] I k′-1 is the current value of the previous sampling point in channel j', set to 0.020 A;

[0155] Δt is the time interval between adjacent sampling points, set to 1 ms, that is, 0.001 s;

[0156] I avg,j′ is the average current value after collecting 200 samples in the current 200 ms window of channel j', set to 0.030 A;

[0157] I max,j′ is the maximum current value of the same period of this channel, set to 0.087 A;

[0158] I min,j′ is the minimum current value of the same period of this channel, set to 0.018 A;

[0159] Substitute the parameters into the formula for calculation:

[0160]

[0161] The result 116.81 indicates that the jump intensity of the current sampling point is significantly higher than the background change rate threshold, and the offset degree of the mutated value in the overall sampling window is relatively large. This value will be used in the subsequent decision logic to judge the jump signal intensity level and serve as the direct basis for generating the jump signal identification result.

[0162] S402: Based on the recognition result of the jump signal, collect the ground voltage data of each branch in the corresponding time period, classify the voltage fluctuation direction, analyze the time matching situation between the voltage change direction and the jump current, and obtain the voltage direction linkage characteristic value;

[0163] Based on the recognition result of the jump signal, the system needs to construct a target time window before and after the occurrence time point of the jump event. Generally, the front and back extension times are set to ±10 ms. Extract the sequence of ground voltage sampling values of each branch within this window, and calculate its direction change by comparing adjacent sampling points. If the voltage at the current point is higher than the previous sampling point, it is judged as the positive direction, otherwise it is the negative direction. Count the direction consistency in the continuous sequence. If the number of direction reversals ≤ 1, it is marked as unidirectional fluctuation. If the number of alternating direction changes ≥ 2, it is marked as disordered fluctuation. Then calculate the time difference between the occurrence point of the jump current event and the occurrence points of the voltage changes of each branch, and use the following formula to extract the linkage characteristic value:

[0164] L j =T v,j -T i ;

[0165] Among them, L j is the time difference between the voltage and current jumps of branch j, T v,j is the first occurrence time of the voltage fluctuation of branch j, and T i is the occurrence time of the jump current event.

[0166] Assume that the jump time is 1005 ms and the starting time of the voltage fluctuation of branch CH02 is 1002 ms, then:

[0167] L2 = 1002 - 1005 = -3 ms;

[0168] This time difference is less than the preset linkage window (±5 ms), and it is judged that there is a linkage relationship. All branches that meet the linkage judgment conditions are written into the voltage linkage table, marked with the directionality (positive or negative), the linkage time difference, and normalized to the linkage characteristic score, and finally the voltage direction linkage characteristic value is generated.

[0169] S403: According to the voltage direction linkage characteristic value and the matching degree, identify the leakage branch and generate the branch positioning determination result;

[0170] According to the voltage direction linkage characteristic value, the system normalizes the linkage characteristic scores of each branch and judges the direction consistency with the jump current direction. The direction consistency score is set to 1 point, and the smaller the absolute value of the linkage time difference, the higher the score. A matching degree scoring model is constructed, and the total score of the matching degree is set to 10 points. Among them, the direction consistency accounts for 20%, and the reverse normalization value of the time difference accounts for 80%. The following calculation formula is used:

[0171]

[0172] Among them, M j is the matching degree score of branch j, D j is the direction consistency determination value. If the value is 1, the directions are consistent; if it is 0, they are inconsistent. L j is the voltage time difference, and θ is the maximum acceptable linkage time difference, which is set to 10 ms.

[0173] Assume that the directions of branch CH03 are consistent and the time difference is 4 ms, then:

[0174]

[0175] After calculating the scores of each branch, they are sorted. The branch with the highest score is regarded as the leakage branch corresponding to the current jump event. The result is recorded and written into the positioning judgment table with the branch number and the judgment time, and finally the branch positioning judgment result is output.

[0176] Based on the branch positioning judgment result, according to the leakage branch number, send a closing control command to the relay configured for the leakage branch, and monitor the closing feedback status signal in real time. Combining the time of the leakage event, the number and location of the charging pile, matching and sending the alarm information, the steps for obtaining the charging pile monitoring record are specifically as follows:

[0177] S501: Based on the branch positioning judgment result, according to the number of the leakage branch, locate the target relay control unit, send a closing control instruction to the relay, monitor the closing state feedback signal of the relay in real time, and obtain the relay closing response information;

[0178] Based on the branch positioning judgment result, obtain the number of the target branch where leakage occurs currently. Extract the corresponding relationship between each number and the relay control unit in the relay configuration file, match and locate the target branch number with the relay number, call the relay number information to access the control channel, set the control parameters and send the closing command. At the same time, record the time node when the control signal is sent, set the relay response time monitoring period to 300 ms, and through the internal status reading module, detect whether the relay status feedback signal completes the switch from the off state to the on state within this period, and judge whether the relay completes the closing operation. Use the formula:

[0179] R j = T s - T r ;

[0180] Among them, R j is the relay closing response delay, T s is the time when the control instruction is sent, T r is the time when the closing state feedback signal is received. Set T s= 12.500 s, T r = 12.762 s, substitute the set value for calculation:

[0181] R j = 12.762 - 12.500 = 0.262 s;

[0182] The calculation results show that the relay completes the closing response, and the response delay is within the allowable range. According to the judgment results, record the state change of the relay and the closing delay time, and obtain the relay closing response information.

[0183] S502: Call the relay closing response information, combine the time node of the leakage event and the branch number information, extract the device number and physical installation location of the current charging pile, and construct a leakage event information set;

[0184] Call the relay closing response information, retrieve and extract the charging pile configuration file through the branch number information, establish the binding relationship between the relay number and the corresponding branch, extract the control module number corresponding to the branch, further read the unique device number of the charging pile body and its installation positioning data, and according to the number address mapping table entered during on-site installation, correspond to the physical location of the current branch, determine the actual geographical location coordinate information and the charging pile number at the moment of the leakage event, extract the leakage determination timestamp recorded in the system, and jointly package the above number, location information and time node data, and construct a complete leakage information structure in chronological order. The fields in this structure include the leakage branch number, relay number, closing response status, control module number, device number, physical location coordinates and determination time value, forming a leakage event information set.

[0185] S503: According to the leakage event information set, match the alarm information and send it to the management personnel, and generate a charging pile monitoring record;

[0186] According to the constructed leakage event information set, retrieve the preset matching rule set from the alarm policy library. The rule set establishes a matching index table according to three parameters: branch number, device number, and timestamp. The matching rule uses the field matching method. If all three fields match, it is marked as an alarm hit item. If the match is successful, generate alarm information content containing the current alarm level, event code, recommended handling plan, etc., send the alarm information structure to the remote alarm system management terminal, and at the same time record the alarm content and time in the local system log, and generate a unique alarm serial number, establish the binding relationship between this serial number and the current leakage event information set, record the completion status and communication result of this round of alarm, and finally obtain the charging pile monitoring record.

[0187] Please refer to Figure 2, a DC charging pile insulation monitoring system, the DC charging pile insulation monitoring system is used to execute the above-mentioned DC charging pile insulation monitoring method, the system comprises:

[0188] The voltage offset calibration module monitors the voltage value of each branch and the bus voltage value in the DC charging pile in real time, extracts the voltage difference between each branch and the bus, and adjusts the measurement compensation parameters according to the voltage offset direction and change amplitude of each branch in continuous sampling to obtain the branch voltage calibration compensation value;

[0189] The insulation resistance correction module collects the insulation resistance observation value of each branch cycle in real time based on the branch voltage calibration compensation value, compares it with the set insulation resistance standard threshold, and combines the fluctuation of each branch to build a correction reference baseline, make an offset adjustment to the observation value, and generate the insulation resistance correction value;

[0190] The leakage drift compensation module collects the static current sampling sequence of each channel under no-load state based on the insulation resistance correction value, analyzes the offset amplitude and direction of the sampling data, identifies the offset channel and adjusts the compensation parameters to obtain the static drift compensation value;

[0191] The fault branch identification module obtains the corrected real-time current data based on the static drift compensation value, extracts the jump current amplitude of each branch, and simultaneously obtains the direction of voltage change to ground within the jump cycle. According to the linkage characteristics of current and voltage changes, the leakage branch is identified and the branch location determination result is obtained;

[0192] The linkage control recording module identifies the leakage branch number based on the branch positioning judgment result, locates the relay control unit and sends a closing command, collects the relay feedback signal status, combines the event time, equipment number, and physical location, matches the alarm content and sends it, and establishes the charging pile monitoring record.

[0193] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware, or any combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions according to the embodiments of the present invention are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that contains one or more collections of available media. The available media can be magnetic media (such as floppy disks, hard disks, magnetic tapes), optical media (such as DVDs), or semiconductor media. The semiconductor media can be a solid-state drive.

[0194] It should be understood that the term "and / or" in this document is merely a description of the association relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural. Additionally, the character " / " in this document generally represents an "or" relationship between the associated objects before and after, but it may also represent an "and / or" relationship, which can be understood specifically with reference to the context before and after.

[0195] In the present invention, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, and c can be single or multiple.

[0196] It should be understood that in various embodiments of the present invention, the magnitudes of the sequence numbers of the above processes do not imply the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0197] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0198] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the devices, apparatuses, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be described herein again.

[0199] In several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be electrical, mechanical, or other forms.

[0200] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0201] In addition, the functional units in each embodiment of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0202] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs.

[0203] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A DC charging pile insulation monitoring method, characterized in that, The method includes: S1: Monitor the voltage values of each branch and the bus voltage in the DC charging pile in real time, analyze the offset direction and offset amplitude of each branch within a continuous operation cycle, and combine the voltage change trend of the branch to adjust the measurement compensation parameters of the branch to obtain the branch voltage calibration compensation value; S2: Call the branch voltage calibration compensation value, obtain the insulation resistance observation value of the branch in real time and compare it with the set insulation resistance standard threshold, combine the observed fluctuation degree of the branch in the execution sequence, compare the fluctuation degree of the measured value of each branch resistance value, and correct the observation value of the target branch to generate the insulation resistance correction value; S3: Based on the insulation resistance correction value, extract the drift direction and offset amplitude in the continuous static sampling of each channel according to the multi-group leakage current channel sampling values of the charging pile in the no-load operation state, calculate the current sampling compensation parameters, and obtain the static drift compensation value; S4: Call the static drift compensation value, monitor the corrected current signal in real time, detect abnormal data, identify the leakage event, and identify the leakage branch by extracting the current jump amplitude of each branch and the change direction of the voltage to the ground, and obtain the branch positioning determination result.

2. The DC charging pile insulation monitoring method according to claim 1, characterized in that The branch voltage calibration compensation value includes the branch voltage offset amplitude, voltage change direction, and measurement compensation parameters. The insulation resistance correction value includes the resistance measurement deviation amplitude, resistance value fluctuation trend, and comparison correction factor. The static drift compensation value includes the offset channel number, offset amplitude parameter, and zero current difference coefficient. The branch positioning determination result is specifically the leakage branch number, current mutation amplitude, and voltage change direction.

3. The DC charging pile insulation monitoring method according to claim 1, wherein, The steps of monitoring the voltage values of each branch and the bus voltage in the DC charging pile in real time, analyzing the offset direction and offset amplitude of each branch within a continuous operation cycle, and combining the voltage change trend of the branch to adjust the measurement compensation parameters of the branch to obtain the branch voltage calibration compensation value are specifically as follows: S101: Monitor the voltage values of each branch and the bus voltage in the DC charging pile in real time, compare the voltage values of each branch with the bus voltage value, extract the voltage offset data, and classify and number the offset data sequence of each branch to obtain the branch voltage difference sequence value; S102: Based on the branch voltage difference sequence value, analyze the offset direction and offset amplitude of each branch within a continuous operation cycle, evaluate the change of the voltage offset in multiple samplings, and obtain the branch voltage offset trend data; S103: Call the branch voltage offset trend data, adjust the measurement compensation parameters in the voltage sampling channel according to the voltage offset direction and offset amplitude of each branch, and obtain the branch voltage calibration compensation value.

4. The DC charging pile insulation monitoring method according to claim 3, wherein, The steps of calling the branch voltage calibration compensation value, obtaining the insulation resistance observation value of the branch in real time and comparing it with the set insulation resistance standard threshold, combining the observed fluctuation degree of the branch in the execution sequence, comparing the fluctuation degree of the measured value of each branch resistance value, and correcting the observation value of the target branch to generate the insulation resistance correction value are specifically as follows: S201: Call the branch voltage calibration compensation value, obtain the insulation resistance observation value of each branch in real time, combine the preset insulation resistance standard threshold, analyze the deviation of the current cycle of each branch by calculating the difference between the observation value and the standard threshold of each branch, and obtain the insulation resistance difference data; S202: Based on the insulation resistance difference data, collect the continuous observation values of each branch within the execution sequence, calculate the fluctuation amplitude of the observation value of each branch, and obtain the branch fluctuation characteristic information; S203: Call the branch fluctuation characteristic information, extract the branch with the smallest fluctuation amplitude as the correction reference set by comparing the fluctuation degree of the measured resistance value of each branch, construct the observation value correction baseline, perform offset correction on the insulation resistance observation value of the target branch, and obtain the insulation resistance correction value.

5. The DC charging pile insulation monitoring method according to claim 4, characterized in that The specific formula for calculating the fluctuation amplitude of the observation value of each branch is: Calculate the fluctuation intensity of the branch resistance observation value; Among them, F i′ represents the fluctuation intensity of the resistance observation value of branch i′, R i′,m′ represents the insulation resistance observation value of branch i′ at the m′-th sampling moment, represents the average insulation resistance observation value of branch i′ over the entire period, R i′,max represents the maximum observation value within the period of branch i′, R i′,min represents the minimum observation value within the period of branch i′, n′ represents the total number of samplings within the period of branch i′, i′ represents the branch number being currently analyzed, and m′ represents the sampling point number within the branch.

6. The DC charging pile insulation monitoring method according to claim 4, characterized in that, Based on the insulation resistance correction value, the steps of extracting the drift direction and offset amplitude in the continuous static sampling of each channel according to the multi-group leakage current channel sampling values of the charging pile in the no-load operation state, calculating the current sampling compensation parameter, and obtaining the static drift compensation value are specifically as follows: S301: Based on the insulation resistance correction value, collect the continuous static current sampling values of multiple leakage current channels of the charging pile in the no-load operation state, extract the direction change and offset amplitude in the sampling sequence of each channel, and obtain the leakage channel offset characteristic information; S302: Call the leakage channel offset characteristic information, identify the offset channel according to the deviation between the static sampling value of each channel and the preset zero-current reference value, and obtain the channel drift identification result; S303: According to the channel drift identification result, extract the sampling offset of the offset channel, combine the sampling direction change trend, calculate the current sampling compensation parameter, and generate the static drift compensation value.

7. The DC charging pile insulation monitoring method according to claim 6, wherein The steps of calling the static drift compensation value, monitoring the corrected current signal in real time, detecting abnormal data, identifying the leakage event, and identifying the leakage branch by extracting the current jump amplitude and the change direction of the ground voltage of each branch to obtain the branch positioning determination result are specifically as follows: S401: Call the static drift compensation value, detect abnormal data by monitoring the corrected current signal in real time, extract the jump point signal in the current signal, and obtain the jump signal identification result; The specific formula for extracting the jump point signal in the current signal is: Calculate the jump amplitude value; Among them, represents the corrected jump amplitude value of the k'-th point in channel j', I k′ represents the leakage current value of the k'-th sampling point in channel j', I k′-1 represents the leakage current value of the (k'-1)-th sampling point in channel j', Δt represents the sampling time interval between two adjacent sampling points, I avg，j′ represents the average value of the current values of all sampling points in channel j' during the current detection period, I max,j′ represents the maximum current value in channel j' during the current period, I min,j′ represents the minimum current value in channel j' during the current period, k' represents the serial number of the k'-th sampling point used for jump recognition in the current channel, and j' represents the serial number of the leakage current detection channel currently being analyzed; S402: Based on the jump signal identification result, collect the ground voltage data of each branch in the corresponding time period, classify the voltage fluctuation direction, analyze the time matching situation between the voltage change direction and the jump current, and obtain the voltage direction linkage characteristic value; S403: According to the voltage direction linkage characteristic value, identify the leakage branch according to the matching degree, and generate the branch positioning determination result.

8. The DC charging pile insulation monitoring method according to claim 1, characterized in that, The method further includes: S5: Based on the branch location determination result, according to the leakage branch number, a closing control command is sent to the relay configured for the leakage branch, and the closing feedback state signal is monitored in real time. Combined with the time of the leakage event, the number and location of the charging pile, the alarm information is matched and sent to obtain the charging pile monitoring record; The charging pile monitoring record specifically refers to the closing control signal, alarm matching information, and leakage event processing record.

9. The DC charging pile insulation monitoring method according to claim 8, wherein, Based on the branch location determination result, according to the leakage branch number, a closing control command is sent to the relay configured for the leakage branch, and the closing feedback state signal is monitored in real time. Combined with the time of the leakage event, the number and location of the charging pile, the alarm information is matched and sent, and the steps of obtaining the charging pile monitoring record are specifically as follows: S501: Based on the branch location determination result, locate the target relay control unit according to the number of the leakage branch, send a closing control instruction to the relay, monitor the closing state feedback signal of the relay in real time, and obtain the relay closing response information; S502: calling the relay closure response information, combining the time node of the leakage event and the branch number information, extracting the device number and physical installation location of the current charging pile, and constructing a leakage event information set; S503: According to the leakage event information set, the alarm information is matched and sent to the management personnel to generate a charging pile monitoring record.

10. A DC charging pile insulation monitoring system, characterized in that, The system is used to implement the DC charging pile insulation monitoring method according to any one of claims 1 to 9, and the system includes: The voltage offset calibration module monitors the voltage value of each branch and the bus voltage value in the DC charging pile in real time, extracts the voltage difference between each branch and the bus, and adjusts the measurement compensation parameters according to the voltage offset direction and change amplitude of each branch in continuous sampling to obtain the branch voltage calibration compensation value; The insulation resistance correction module collects the insulation resistance observation value of each branch cycle in real time based on the branch voltage calibration compensation value, compares it with the set insulation resistance standard threshold, and combines the fluctuation of each branch to build a correction reference baseline, offset adjust the observation value, and generate an insulation resistance correction value; The leakage drift compensation module collects the static current sampling sequence of each channel under no-load state based on the insulation resistance correction value, analyzes the offset amplitude and direction of the sampling data, identifies the offset channel and adjusts the compensation parameters to obtain the static drift compensation value; The fault branch identification module obtains the corrected real-time current data based on the static drift compensation value, extracts the jump current amplitude of each branch, and simultaneously obtains the direction of voltage change to ground within the jump period, identifies the leakage branch according to the linkage characteristics of current and voltage changes, and obtains the branch location determination result; The linkage control recording module identifies the leakage branch number based on the branch positioning judgment result, locates the relay control unit and sends a closing command, collects the relay feedback signal status, combines the event time, equipment number, and physical location, matches the alarm content and sends it, and establishes the charging pile monitoring record.

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