Copper bar connection state detection method and system

Abstract

The invention discloses a copper bar connection state detection method and system, particularly relates to the technical field of copper bar state detection, and is used for solving the problem of poor early recognition of copper bar connection deterioration. According to the method, resistance and temperature rise conditions at the joint of the copper bars are measured synchronously in the load change process, signal denoising is realized in combination with finite difference filtering, and characteristic evolution conditions at the joint are captured; the method comprises the steps of determining an analysis window based on a real-time load change event, constructing a thermoelectric track point set and dividing a load rising and falling period, forming a continuous dynamic thermoelectric response curve, dividing a temperature rising track and a temperature falling track through a temperature change trend, extracting a resistance drift amount and a hysteresis loop area, and identifying a connection degradation trend and a structure fatigue characteristic. And connection state information generated by thermal stress action and thermal cycle asymmetry is obtained during load change, and a detection strategy is adjusted according to an analysis result, so that early degradation identification and intelligent risk grading of the copper bar connection state are carried out, and the sensitivity and accuracy of copper bar detection are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of copper busbar status detection. More specifically, the present invention relates to a method and system for detecting the connection status of copper busbars. Background Art

[0002] As an important electrical connection component in the power transmission and distribution system, copper busbars are widely used in substations, distribution cabinets, power equipment, and large industrial electrical systems to carry out the tasks of large current transmission and distribution. Due to the excellent electrical conductivity, corrosion resistance, and mechanical workability of copper materials, copper busbars can effectively reduce energy losses and improve the overall efficiency and reliability of electrical systems. Copper busbar connections are usually achieved through methods such as bolt pressing, welding, or plugging. The contact resistance, mechanical strength, and thermal stability of the connection part directly affect the operating performance and safety level of the entire electrical system. Ideally, copper busbar connections should ensure a low and stable contact resistance to minimize voltage drop and heat generation during power transmission.

[0003] Deficiencies of the prior art: In the existing copper busbar connection status detection technologies, it is usually mainly dependent on the absolute change of the single-point contact resistance value, temperature rise monitoring, or periodic visual inspection to evaluate the connection status. However, the static detection based solely on the resistance value cannot effectively reflect the deterioration evolution process of the connection under dynamic thermal stress, and cannot timely capture the cumulative trend and local abnormal fluctuations of resistance drift, resulting in the difficulty of timely identification of early creep degradation and abnormal contact voltage drop. Secondly, there is a lack of systematic analysis of the hysteresis characteristics and stability changes of the connection structure during the complete thermal cycle, and it is impossible to quantify the path asymmetry and structural fatigue accumulation during the heating and cooling processes, thus missing the early warning of the potential fatigue instability risk of the connection. There is a lack of a systematic determination mechanism for the dual characteristics of dynamic deterioration behavior and structural stability degradation, resulting in insufficient accuracy and pertinence of the copper busbar connection status assessment results. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a method and system for detecting the connection status of copper busbars to solve the problem of poor early identification of copper busbar connection deterioration in the above-mentioned background art.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for detecting the connection status of copper busbars, comprising the following steps:

[0007] Measure the contact resistance at the copper busbar connection during the load change process, and at the same time deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals, eliminate noise through finite difference filtering, and perform registration of resistance and temperature signals;

[0008] Based on the load change events monitored in real time, determine the analysis window and intercept the synchronous data, construct a thermoelectric trajectory point set from the synchronous data, and determine the load rise and fall periods to form a continuous thermoelectric dynamic trajectory;

[0009] Divide the heating and cooling section trajectories according to the temperature change trend, extract the resistance drift amount during the load rise in the heating section, determine the deterioration trend of the copper busbar connection, and extract the hysteresis loop area in the complete thermal cycle trajectory to perform the state determination during the load change;

[0010] During the load change, obtain the thermal stress and the connection state information generated during the thermal cycle and perform analysis, and adjust the detection strategy according to the analysis result of the connection state.

[0011] In a preferred embodiment, during the load change process, measure the contact resistance at the copper busbar connection, and at the same time arrange high-precision temperature sensors in the connection area to synchronously collect the local temperature rise signal, eliminate noise through finite difference filtering, and perform registration of the resistance and temperature signals. The specific process is as follows:

[0012] Apply a constant current that does not affect the main current of the copper busbar at the copper busbar, and collect the small voltage drop at both ends of the copper busbar connection to determine the copper busbar contact resistance;

[0013] In the copper busbar connection joint area, arrange high-precision thermocouples or temperature sensors to collect the original local temperature signal at the copper busbar connection joint, and after normalizing the collected original local temperature signal, obtain the effective temperature;

[0014] Combine the contact resistance and local temperature data into a unified synchronous data frame. The synchronous data frame includes the copper busbar connection contact resistance, the copper busbar connection local temperature, and a unified time stamp;

[0015] Use adaptive bidirectional finite difference filtering to process and filter the noise of each component in the synchronous data frame respectively.

[0016] In a preferred embodiment, based on the load change events monitored in real time, determine the analysis window and intercept the synchronous data, construct a thermoelectric trajectory point set from the synchronous data, and determine the load rise and fall periods to form a continuous thermoelectric dynamic trajectory. The specific process is as follows:

[0017] Real-time detect the load change events, intercept the corresponding dynamic response analysis window, and monitor the main current I main (t) of the copper busbar, detect the current change rate, and calculate the first derivative dI main / dt of the current. When the following conditions are met, it is determined as the starting point t of the load change s : where δ I is the current change rate threshold;

[0018] Set the length T of the load change analysis window win , and intercept the data frames collected synchronously within the interval;

[0019] From the analysis window [t s , t s + T win , extract the smoothed synchronous data at each moment Among them, is the synchronous resistance sequence, is the synchronous temperature sequence;

[0020] Use the synchronous resistance sequence as the vertical axis and the synchronous temperature sequence as the horizontal axis to construct a thermoelectric trajectory point set: C is the set of resistance and temperature trajectory points, used to describe the continuous thermoelectric dynamic response process;

[0021] Calculate the minimum and maximum values of the temperature sequence within the current load change window, and normalize the minimum and maximum values of the resistance sequence to obtain the trajectory point set of temperature and resistance.

[0022] In a preferred embodiment, the heating section and the cooling section trajectories are divided according to the temperature change trend, and the specific steps are as follows:

[0023] The trajectory point set is divided into a heating section and a cooling section according to the load thermal response cycle;

[0024] If the temperature difference between the current moment and the next moment is greater than zero and the temperature shows a positive increase, the time period is determined to be the heating section. If the temperature difference is less than zero, that is, the temperature decreases, it is determined to be the cooling section.

[0025] In a preferred embodiment, during the heating section, extract the resistance drift amount during the load increase, determine the deterioration trend at the copper bar connection, and extract the area of the hysteresis loop in the complete thermal cycle trajectory to perform the state determination during the load change. The specific process is as follows:

[0026] According to the normalized temperature signal T norm (t i ) calculate the temperature change rate ΔT(t i ) at each moment: ΔT(t i ) = T norm (t i+1 ) - T norm (t i ), where T norm (t i+1 ) represents the moment t i+1 ;

[0027] Define the segmentation rule: If ΔT(t i ) > 0, it is determined to be the load increase section; if ΔT(ti ) < 0, it is determined as the load decreasing section;

[0028] Divide the trajectory point set according to the segmentation rule to obtain the load increasing section set and the load decreasing section set;

[0029] Analyze the trajectories of the load increasing period and the load decreasing period extracted by segmentation to determine the response characteristics of different stages of the performance of the copper bar connection with the change of thermal stress;

[0030] In the load increasing section set, extract the normalized resistance signal R norm (t i ), and define the resistance drift as an integral measure of the resistance change during the load increasing period;

[0031] The resistance drift is defined as: where, T up is the load increasing duration, obtained by the difference between the start and end times of the load increasing section; t s , t e are the start and end times of the load increasing section respectively;

[0032] Construct a hysteresis loop profile with the load increasing section and the load decreasing section in the trajectory point set as the boundaries, and use the discrete curve integral method to calculate the hysteresis area A H ;

[0033] Take the point set of the trajectory loop arranged in ascending order of temperature as the hysteresis area: where, N is the total number of trajectory points.

[0034] In a preferred embodiment, obtain and analyze the thermal stress and the connection state information generated during the thermal cycle, and the specific process is as follows:

[0035] Obtain the thermal stress and the connection state information generated during the thermal cycle. The connection state information includes resistance drift information and hysteresis response information. The resistance drift information includes the thermal stress degradation dynamic index, and the hysteresis response information includes the thermal cycle asymmetric stability index;

[0036] The thermal stress degradation dynamic index represents the resistance change of the copper bar connection caused by the action of thermal stress during the load increasing period;

[0037] The thermal cycle asymmetric stability index represents the asymmetry and stability changes of the thermoelectric behavior at the connection after the copper bar connection experiences a complete load heating and cooling cycle;

[0038] Compare the thermal stress degradation dynamic index with the thermal stress degradation dynamic threshold, and compare the thermal cycle asymmetric stability index with the thermal cycle asymmetric stability threshold.

[0039] In a preferred embodiment, the detection strategy is adjusted according to the connection status analysis result, and the specific process is as follows:

[0040] Compare the dynamic thermal stress degradation index with the dynamic thermal stress degradation threshold, and compare the thermal cycle asymmetric stability index with the thermal cycle asymmetric stability threshold. Divide it into four cases according to the comparison results and make different strategy adjustments;

[0041] In the first case, if the dynamic thermal stress degradation index is less than or equal to the dynamic thermal stress degradation threshold, and at the same time the thermal cycle asymmetric stability index is also less than or equal to the thermal cycle asymmetric stability threshold, then maintain the regular inspection cycle, monitor according to the normal detection plan, and there is no need to increase the maintenance frequency or take additional intervention measures;

[0042] In the second case, if the dynamic thermal stress degradation index is greater than the dynamic thermal stress degradation threshold, while the thermal cycle asymmetric stability index is still less than or equal to the thermal cycle asymmetric stability threshold, then shorten the subsequent detection cycle, increase the drift trend tracking, and arrange a local connection inspection;

[0043] In the third case, if the dynamic thermal stress degradation index is less than or equal to the dynamic thermal stress degradation threshold, while the thermal cycle asymmetric stability index is greater than the thermal cycle asymmetric stability threshold, then take accelerated inspection measures to check the connection crimping status, bolt tightening condition and physical state of the contact interface;

[0044] In the fourth case, if the dynamic thermal stress degradation index is greater than the dynamic thermal stress degradation threshold, and the thermal cycle asymmetric stability index is greater than the thermal cycle asymmetry stability, then immediately arrange a shutdown for maintenance, check and replace the severely deteriorated connection parts, and simultaneously conduct a synchronous investigation on the surrounding copper busbar connection units.

[0045] A copper busbar connection status detection method system for implementing the above-mentioned copper busbar connection status detection method, includes:

[0046] A data acquisition module for copper busbar connections, which is used to measure the contact resistance at the copper busbar connection during the load change process, and at the same time deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals, eliminate noise through finite difference filtering, and perform registration of resistance and temperature signals;

[0047] A thermoelectric trajectory determination module, which is used to determine the analysis window and intercept synchronous data based on the real-time monitored load change events, construct a set of thermoelectric trajectory points from the synchronous data, and determine the load rising and falling periods to form a continuous thermoelectric dynamic trajectory;

[0048] A load trend determination module, which is used to divide the heating section and the cooling section trajectories according to the temperature change trend, extract the resistance drift amount during the load increase period in the heating section, determine the deterioration trend of the copper busbar connection, and extract the area of the hysteresis loop in the complete thermal cycle trajectory to perform the state determination during the load change;

[0049] A strategy adjustment module, which is used to obtain the thermal stress and the connection state information generated during the thermal cycle during the load change, analyze them, and adjust the detection strategy according to the analysis result of the connection state.

[0050] The technical effects and advantages of the present invention:

[0051] By synchronously measuring the contact resistance and the local temperature rise signal at the copper busbar connection during the load change process, and combining finite difference filtering to achieve signal denoising and time registration, the present invention can accurately capture the evolution of the microscopic characteristics of the connection interface. Based on the real-time load change event, an analysis window is determined, a thermoelectric trajectory point set is constructed and the load rise and fall periods are divided to form a continuous dynamic thermoelectric response curve, realizing continuous tracking of the whole process of the connection being heated and disturbed. By dividing the heating and cooling trajectories according to the temperature change trend, extracting the resistance drift amount and the area of the hysteresis loop, the present invention can systematically identify the connection deterioration trend and the structural fatigue characteristics. Further, during the load change, the connection state information generated by the thermal stress action and the thermal cycle asymmetry is obtained, and the detection strategy is dynamically adjusted according to the analysis result, realizing early deterioration identification and intelligent risk grading of the copper busbar connection state, improving the detection sensitivity and accuracy, and enhancing the dynamic perception ability of the healthy evolution process of the connection. Description of the Drawings

[0052] Figure 1 It is a flowchart of a method for detecting the connection state of a copper busbar according to the present invention.

[0053] Figure 2 It is a structural schematic diagram of a system for detecting the connection state of a copper busbar according to the present invention. Detailed Embodiments

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0055] Embodiment 1: As Figure 1 shown, a method for detecting the connection state of a copper busbar includes the following steps:

[0056] Measure the contact resistance at the copper busbar connection during the load change process. At the same time, deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals. Eliminate noise through finite difference filtering and perform registration of resistance and temperature signals.

[0057] Based on the load change events monitored in real time, determine the analysis window and intercept the synchronous data. Construct a thermoelectric trajectory point set from the synchronous data, and determine the load rise and fall periods to form a continuous thermoelectric dynamic trajectory.

[0058] Divide the trajectory into a heating section and a cooling section according to the temperature change trend. Extract the resistance drift amount during the load rise in the heating section to determine the deterioration trend of the copper busbar connection. And extract the area of the hysteresis loop in the complete thermal cycle trajectory to conduct state determination during the load change.

[0059] During the load change, obtain the thermal stress and connection state information generated during the thermal cycle and conduct analysis. Adjust the detection strategy according to the analysis results of the connection state.

[0060] During the detection of the copper busbar connection state, the change in the electrical performance at the connection is affected by various factors. Among them, the change in the microscopic contact characteristics caused by thermal stress is an important and easily overlooked evolution process. When the copper busbar operates under a large load, the current passing through causes the temperature of the body to rise, and the copper busbar itself and its connection points will undergo thermal expansion and force changes, resulting in dynamic drift of the contact resistance. Therefore, synchronously and continuously collect the resistance change and local temperature change at the copper busbar connection, establish a thermal-electric dynamic correlation, and accurately identify the early signs of connection deterioration.

[0061] Step 1: Synchronously collect the copper busbar contact resistance and local temperature data. The specific steps are as follows:

[0062] The contact resistance at the copper busbar connection terminal is the most direct electrical parameter to evaluate the connection health status. The deterioration of the connection state (such as loosening, oxidation) usually first shows as a slight increase in the contact resistance.

[0063] Use the perturbation excitation injection mechanism, that is, inject a small constant current under the condition of not affecting the main current transmission of the copper busbar, and collect the small voltage drop at both ends of the copper busbar connection to calculate the contact resistance.

[0064] The excitation current must be much smaller than the main current of the copper busbar, usually selected to avoid perturbation. And the differential voltage acquisition unit adopts a high common-mode rejection ratio amplifier design to suppress the noise introduced by the large-current main circuit. At the same time, the sampling frequency is set to be more than 10 times the main frequency component of the load change frequency, usually taking 10Hz to 50Hz.

[0065] The real-time contact resistance calculation uses the modified expression of Ohm's law: where, R cR(t) is the instantaneous copper busbar connection contact resistance at time t; V c V(t) is the voltage difference collected at both ends of the copper busbar connection at time t; I c is the applied constant small excitation current.

[0066] Normalize the synchronized acquisition data of the local temperature of the copper busbar, that is, in the copper busbar connection joint area, arrange high-precision thermocouples or PT100 temperature sensors, select the surface area within 5-10 mm from the center of the connection bolt as the temperature measurement base point, and after the sensor output signal is processed by the preamplifier and temperature drift compensation module, collect the local temperature signal;

[0067] After the original local temperature signal collected is processed by temperature drift normalization, the effective temperature is calculated: T s (t) = T raw (t) - T env (t) + T ref , where, T s (t) is the normalized local temperature at the copper busbar connection at time t, T raw (t) is the original collected temperature value T env (t) at time t, T ref is the environmental background temperature, and T

[0068] After normalization, the local temperature signal eliminates environmental interference and can reflect the temperature evolution of the copper busbar connection under the action of current-carrying thermal stress.

[0069] Set a unified system clock and adopt the IEEE 1588 high-precision time synchronization protocol to ensure that all acquisition units operate with the same time reference. At each time point t, the contact resistance and local temperature data are merged into a unified synchronized data frame, and the synchronized data frame includes the copper busbar connection contact resistance, the local temperature of the copper busbar connection, and a unified timestamp;

[0070] Use adaptive bidirectional finite difference filtering to process each component in the synchronized data frame respectively, suppress high-frequency noise components, and at the same time avoid losing dynamic response due to over-filtering of the signal. The filtering formula is: where X(t) represents any one of the contact resistance or local effective temperature rise; is the smoothed signal, X(t) is the original signal; Δt is the sampling interval time.

[0071] It should be noted that the finite difference form needs to maintain the first-order perturbation characteristic, not erase short-term mutations, and the smoothing window is fixed at the current sampling point and one point before and after it respectively, so as to ensure low latency.

[0072] During the actual load operation of the copper bar connection, due to the Joule heat caused by the current change, the local temperature will change dynamically, accompanied by a slight drift of the contact resistance at the connection. This change is not only directly related to the load level but also modulated by the microscopic contact surface change caused by thermal stress. Therefore, during the detection period, it is necessary to capture the dynamic response trajectories of the resistance and temperature of the copper bar during load fluctuations and establish their characteristic curves;

[0073] Step 2: Establish the dynamic trajectories of resistance and temperature during load changes. The specific steps are as follows:

[0074] Real-time detect load change events and intercept the corresponding dynamic response analysis window to monitor the main current I of the copper bar main (t), detect the current change rate, and calculate the first derivative dI of the current change main / dt. When the following conditions are met, it is determined as the starting point t of the load change s : where δ I is the current change rate threshold;

[0075] Set the load change analysis window length T win , and intercept the data frames collected synchronously within the interval;

[0076] During the load change, the resistance at the connection of the copper bar changes regularly with the temperature. Under normal connection conditions, the resistance change trend has a good consistency with the temperature rise change trend; when the connection deteriorates, abnormal phenomena such as non-linear drift and hysteresis will appear in the resistance change trajectory with temperature;

[0077] From the analysis window [t s , t s +T win , extract the smoothed synchronous data at each moment

[0078] Take the synchronous resistance sequence as the vertical axis and the synchronous temperature sequence as the horizontal axis to construct a thermoelectric trajectory point set: C is the set of resistance and temperature trajectory points, describing the continuous thermoelectric dynamic response process;

[0079] Calculate the minimum and maximum values of the temperature sequence within the current load change window, and normalize the minimum and maximum values of the resistance sequence to obtain the trajectory point set of temperature and resistance;

[0080] Divide the trajectory point set into a heating section and a cooling section according to the load thermal response cycle. If the temperature difference between the current moment and the next moment is greater than zero, that is, the temperature is increasing positively, then the time period is determined as the heating section. If the temperature difference is less than zero, that is, the temperature is decreasing, then it is determined as the cooling section.

[0081] In the detection of the copper busbar connection state, the load change (i.e., current change) directly causes the temperature change of the copper busbar. The working current in the main circuit of the copper busbar is monitored in real time to construct the time series of the main current. The first-order difference or derivative signal of this series is obtained to get the current change rate curve. When the absolute value of this rate curve first exceeds the preset current change rate threshold at a certain moment, it is considered that a significant load mutation has occurred in the system, and this time point is determined as the starting moment of the load change, that is, the starting point of the thermal response window.

[0082] The temperature rising stage (heating period) and the temperature falling stage (cooling period) correspond to the stress responses of the copper busbar connection interface under different thermodynamic environments.

[0083] As the temperature of the copper busbar gradually rises, the contact interface pressure drop changes most significantly under the combined effects of heat expansion, creep, material softening, etc. at the connection. If there is slight deterioration, the resistance shows an obvious upward trend, the temperature of the copper busbar drops, and the connection stress is gradually released. If fatigue or surface deterioration occurs at the connection interface, the resistance drop lag phenomenon is prominent. Therefore, the trajectory data is segmented into the heating period and the cooling period to capture the response characteristics of the above different deterioration mechanisms respectively, and then the drift characteristics and hysteresis characteristics are accurately extracted.

[0084] Step 3: Extract the resistance drift and hysteresis characteristic indexes, and the specific steps are as follows:

[0085] According to the normalized temperature signal T norm (t i ) Calculate the temperature change rate at each moment: ΔT(t i ) = T norm (t i+1 ) - T norm (t i ), where T norm (t i+1 ) represents the moment of t i+1 ;

[0086] Define the segmentation rule: If ΔT(t i ) > 0, it is determined as the load rising section; if ΔT(t i ) < 0, it is determined as the load falling section; Divide the trajectory point set according to the above rules to obtain the rising section set and the falling section set;

[0087] By segmenting and extracting the trajectories in the load rising period and the load falling period, the response characteristics of the connection performance in different stages with the change of thermal stress can be clearly analyzed.

[0088] During the connection degradation process, the resistance at the copper busbar connection usually shows an abnormal increase during the load rise. Even if the temperature change range is controlled, the drift amount reflects the degree of contact degradation of the connection surface or the decrease in the pressing force. Similarly, calculate the resistance drift amount during the load rise as an important quantitative feature of the connection state change;

[0089] In the set of load rise segments, extract the normalized resistance signal R norm (t i ), and define the resistance drift amount as an integral measure of the resistance change during the load rise;

[0090] Let t s and t e be the start and end times of the load rise segment respectively, then the resistance drift amount is defined as: where, T up is the load rise duration, obtained by the difference between the start and end times of the load rise segment;

[0091] The resistance drift amount measures the resistance change trend during the entire load rise through integration, which can effectively amplify the tiny degradation signal, avoid the influence of the contingency of single-point measurement, and improve the detection robustness.

[0092] If there is an obvious hysteresis loop in the resistance and temperature trajectories of the copper busbar connection during the heating and cooling process, it indicates that there are problems such as plastic deformation, surface aging or unstable pressing on the connection surface. The size of the hysteresis area directly reflects the energy dissipation and degradation degree of the connection under the thermal cycling stress;

[0093] Construct a hysteresis loop contour with the rising and falling segments in the trajectory as the boundaries, and use the discrete curve integral method to calculate the hysteresis area A H ;

[0094] Let the point set of the trajectory loop arranged in ascending order of temperature be the hysteresis area: The hysteresis area can be approximately calculated by the discrete Green's formula, where N is the total number of trajectory points; the larger the hysteresis area, the worse the stability of the connection state.

[0095] Step four, conduct connection state determination and risk grading output, that is, obtain the dynamic trajectories of the copper busbar connection resistance and temperature during the load change, and analyze the resistance drift behavior under the thermal stress and the hysteresis response characteristics during the thermal cycle. The specific steps are as follows:

[0096] During the connection state determination process, analyze the resistance drift behavior under thermal stress and the hysteresis response characteristics during the thermal cycle, that is, obtain the connection state information generated during thermal stress and the thermal cycle. The connection state information includes resistance drift information and hysteresis response information. The resistance drift information includes the thermal stress degradation dynamic index, and the hysteresis response information includes the thermal cycle asymmetric stability index;

[0097] The thermal stress degradation dynamic index is used to quantify the dynamic characteristics of the resistance change caused by thermal stress during the load increase of the copper bus connection. The thermal stress degradation dynamic index not only measures the cumulative degree of resistance drift during the overall load increase of the connection, but also comprehensively reflects the instability of local resistance change and the asymmetric evolution characteristics of the drift rate in the front and back stages. Specifically, the thermal stress degradation dynamic index describes the dynamic evolution of the degradation process of the connection interface under continuous heating conditions by introducing multi-dimensional information such as the cumulative resistance drift amount, the amplitude of the local drift change rate, and the drift rate deviation between the front and back sections;

[0098] The thermal stress degradation dynamic index directly affects the quantification accuracy of the thermal evolution characteristics of the copper bus connection during the load increase. The higher the thermal stress degradation dynamic index, the greater the resistance drift amplitude of the connection interface under heating conditions, the more significant the local instability, and the more uneven the front and back drift evolution, thus reflecting problems such as abnormal increase in voltage drop, local contact degradation, or creep damage accumulation at the connection interface.

[0099] The acquisition logic of the thermal stress degradation dynamic index is as follows:

[0100] Obtain the overall resistance drift amount during the load increase: where is the local drift amount in the temperature sampling point interval j, obtain the normalized contact resistance value R i corresponding to the time sampling point t norm (t i ) and the normalized temperature value T norm (t i+1 ) and the normalized contact resistance R i+1 corresponding to the time sampling point t norm (t i+1 ) and the normalized temperature value T norm (t i+1 ), calculate the local drift change rate, and the calculation expression is: Obtain the maximum local drift change rate FD max (t i ) and the minimum local drift change rate FD min (t i );

[0101] Obtain the time t at the midpoint of the load temperature rise mThe normalized contact resistance value R at norm (t m ), obtain the normalized contact resistance value R at the starting moment t0 of load increase norm (t0), during the load increase process, normalize the temperature to the midpoint moment t m of the normalized temperature value T norm (t m ), obtain the normalized temperature value T at the starting moment t0 of load increase norm (t0), calculate the drift rate of the first half: Obtain the normalized contact resistance value R at the ending moment t N of load increase norm (t N ), obtain the normalized temperature value T at the ending moment t N of load increase norm (t N ), calculate the drift rate of the second half: Calculate the dynamic index of thermal stress deterioration:

[0102] It should be noted that the overall resistance drift is during the load increase period (temperature normalization interval [0, 1]), process the resistance change trajectory, calculate the cumulative integral of the normalized resistance change from the start to the end, and obtain it by accumulating after stratified integration of small intervals; the normalized contact resistance is during the load change period, after synchronously collecting the actual contact resistance of the copper bar connection and performing normalization processing, it is a standardized value used to eliminate the influence of different load conditions and absolute resistance magnitude changes on feature extraction. The same applies to the normalized temperature; the drift rate of the first half represents the average growth rate of the contact resistance of the copper bar connection with temperature change from the start of the load to the moment when the temperature rises to the midpoint (0.5), measuring the deterioration evolution speed in the initial heating stage; the drift rate of the second half represents the average growth rate of the contact resistance with temperature change from the temperature midpoint (0.5) to the completion of load heating (1.0), measuring the deterioration evolution speed in the later heating stage.

[0103] The thermal cycle asymmetric stability index (TCASI) is used to represent the asymmetric and stability change characteristics of the thermoelectric behavior of the copper bar connection after experiencing a complete load heating and cooling cycle process. The thermal cycle asymmetric stability index comprehensively measures the area size of the heating-cooling hysteresis loop, the path resistance range, and the centroid offset of the hysteresis loop, reflecting the energy loss degree, fatigue deterioration degree, and geometric stability degradation of the connection interface under thermal cycle stress. Specifically, the thermal cycle asymmetric stability index can accurately describe the irreversible deterioration characteristics and the trend of expanding structural asymmetry in the thermal cycle;

[0104] The thermal cycle asymmetric stability index can quantify the instability risk of the connection structure in a dynamic thermal environment, assist in determining early failure modes such as interface fatigue, loosening, or microcrack propagation, enhance the ability to dynamically track and classify the decline in connection reliability, and formulate intelligent maintenance strategies;

[0105] The thermal cycle asymmetric stability index directly affects the detection ability of the structural degradation and fatigue evolution of the copper busbar connection during multiple load cycles. The higher the thermal cycle asymmetric stability index, the greater the energy loss at the connection interface during heating and cooling, the more asymmetric the change in path resistance, and the more obvious the geometric stability deviation of the hysteresis loop, indicating that there is a trend of irreversible fatigue damage, loosening, or microcrack propagation inside the connection interface. When the thermal cycle asymmetric stability index continues to rise and breaks through the preset safety range, it usually means that the connection has experienced serious structural stability degradation, and risk intervention or local structural reinforcement should be carried out in a timely manner in combination with the operation strategy to avoid the expansion of electrical system chain failures or safety hazards caused by connection fatigue failure.

[0106] The acquisition logic of the thermal cycle asymmetric stability index is as follows:

[0107] Obtain the heating path and cooling path during the thermal cycle, obtain the average value of all temperature sampling points on the heating path, and calculate the temperature center of the heating path: Among them, is the temperature of the i-th sampling point on the heating path, calculate the resistance center: Among them, is the normalized contact resistance value corresponding to the temperature of the i-th sampling point on the heating path;

[0108] Similarly, obtain the average value of all temperature sampling points on the cooling path, and calculate the temperature center of the cooling path: Among them, is the temperature of the i-th sampling point on the cooling path, calculate the resistance center: Among them, is the normalized contact resistance value corresponding to the temperature of the i-th sampling point on the cooling path; calculate the centroid offset of the hysteresis loop:

[0109] Obtain the resistance and temperature data trajectory of the copper busbar connection during a complete thermal cycle, and process all the resistance values of the obtained cooling path to obtain the trajectory resistance value: Among them, R min 、R max are the minimum resistance value and the maximum resistance value within the entire thermal cycle window; perform the calculation of the thermal cycle asymmetric stability index, and the calculation expression is:

[0110] It should be noted that the heating path refers to the resistance temperature trajectory of the copper bar connection during the temperature rise, which is denoted as the upward trajectory, and the cooling path is the resistance temperature trajectory of the copper bar connection during the temperature drop, which is denoted as the downward trajectory. The geometric centroid of each trajectory is the central position of the trajectory in the temperature-resistance-thermoelectric plane. For the heating path, the coordinates of this central position are the temperature center of the abscissa and the resistance center of the ordinate.

[0111] Set the dynamic threshold of thermal stress degradation to quantitatively determine and classify the state of the dynamic evolution process of the resistance drift of the copper bar connection under the action of thermal stress during the load increase. Since the change trend of the contact resistance of the copper bar connection can sensitively reflect early degradation phenomena such as abnormal voltage drop at the connection interface, material creep, and microscopic contact interface degradation under the action of thermal stress, it is necessary to set a scientific and reasonable dynamic threshold of thermal stress degradation to distinguish the connection state into two major categories: healthy and abnormal.

[0112] Set the asymmetric stability threshold of thermal cycling to quantitatively evaluate and identify risks for the thermoelectric response hysteresis characteristics and structural stability changes of the copper bar connection during a complete load heating and cooling cycle. Since the copper bar connection is susceptible to the cumulative effects of fatigue, creep residue, and local loosening in a long-term thermal cycling environment, resulting in asymmetric changes such as an increase in the area of the hysteresis loop, an increase in the path resistance difference, and an offset of the overall geometric structure in the thermal cycling path, by setting the asymmetric stability threshold of thermal cycling, potential risk connection units can be identified in advance before macroscopic slip or fatigue failure occurs in the connection structure, guiding targeted maintenance decisions;

[0113] According to the levels of the dynamic index of thermal stress degradation and the asymmetric stability index of thermal cycling relative to these two thresholds, it is divided into four typical situations, and each situation corresponds to different judgments and strategy adjustments:

[0114] In the first situation, the dynamic index of thermal stress degradation is less than or equal to the dynamic threshold of thermal stress degradation, and at the same time, the asymmetric stability index of thermal cycling is also less than or equal to the asymmetric stability threshold of thermal cycling. In this case, the overall resistance drift of the copper bar connection under the action of thermal stress changes little, and no obvious hysteresis asymmetry is shown after experiencing thermal cycling, indicating that the connection interface is in a relatively stable working state. From the perspective of degradation characteristics, the overall resistance changes smoothly with the temperature rise, there is no sudden drift or abnormal rate locally, and the heating and cooling paths basically coincide in the resistance-temperature plane, the area of the hysteresis loop is tiny, and the offset of the loop centroid is not obvious. At this time, the engineering risk assessment belongs to the low-risk category, the connection reliability is high, there is no risk of failure temporarily, it is recommended to maintain the regular inspection cycle and monitor according to the normal detection plan, without increasing the maintenance frequency or taking additional intervention measures;

[0115] In the second case, the dynamic index of thermal stress degradation is greater than the dynamic threshold of thermal stress degradation, while the thermal cycle asymmetric stability index is still less than or equal to the thermal cycle asymmetric stability threshold. This situation shows that the resistance drift of the copper busbar connection is large under the action of thermal stress, and the overall degradation trend has initially appeared, but the path is still basically symmetrical during the heating and cooling process, and the hysteresis phenomenon has not significantly expanded. This state shows that the connection interface is affected by thermal stress, resulting in material expansion and changes in the microscopic contact interface, forming an overall abnormal voltage drop trend, but structural fatigue has not yet occurred. The degradation characteristics are manifested in that the overall resistance shows a continuous upward trend with the increase in temperature, and there is a phenomenon of accelerated drift rate change in some areas, but the hysteresis loop is still regular as a whole. The engineering risk assessment belongs to the medium risk level. If it continues to operate without intervention, it may enter the accelerated degradation stage. It is recommended to appropriately shorten the subsequent detection cycle, increase drift trend tracking, and arrange local connection inspections at appropriate times. If necessary, restore the connection crimping force or clean the contact surface to prevent further deterioration;

[0116] In the third case, the dynamic index of thermal stress degradation is less than or equal to the dynamic threshold of thermal stress degradation, while the asymmetric stability index of thermal cycle is greater than the asymmetric stability threshold of thermal cycle. This situation indicates that the overall resistance change trend of the copper busbar connection has not drifted significantly, but the hysteresis path area is enlarged and the loop asymmetry is aggravated under the action of thermal cycle, reflecting the accumulation of thermal fatigue or local slip at the connection interface. The degradation characteristics are that the overall resistance change amplitude is small, but the resistance response at the same temperature in the heating and cooling stages is obviously separated, the hysteresis area is significantly increased, and the center of gravity of the loop has shifted significantly. The engineering risk assessment shows that there are medium and high risks in the connection interface. The main hidden danger is the looseness of the local structure caused by fatigue. If it is operated for a long time, it may cause mechanical instability or local failure. It is recommended to take accelerated inspection measures to check the connection crimping state, bolt tightening and physical state of the contact interface. If necessary, local re-crimping or protective treatment should be taken to curb the trend of fatigue expansion;

[0117] In the fourth case, both the thermal stress degradation dynamic index and the thermal cycle asymmetry stability index are greater than their respective set thresholds, belonging to the most severe comprehensive instability state of degradation. In this case, the copper busbar connection shows a drastic resistance drift under the action of thermal stress, and at the same time, the hysteresis area increases significantly during the thermal cycle, the loop asymmetry is remarkable, the center of gravity shifts severely, and the overall structural response is abnormal. The degradation characteristics include drastic resistance change, unstable drift rate, large deviation of the hysteresis path, and overall position migration of the loop, indicating that the connection interface has lost its due thermal and mechanical stability. The engineering risk assessment determines it as a high-risk or even extremely high-risk state, and serious accidents such as functional failure, local overheating, melting, or electrical open circuit may occur at any time. For such cases, immediate shutdown for maintenance should be arranged, the severely degraded connection parts should be checked and replaced preferentially, and at the same time, the surrounding connection units should be inspected synchronously, and a more stringent subsequent maintenance and monitoring plan should be formulated to prevent the spread of similar faults.

[0118] The present invention synchronously measures the contact resistance and local temperature rise signal at the copper busbar connection during the load change process, combines finite difference filtering to achieve signal denoising and time registration, can accurately capture the evolution of the microscopic characteristics of the connection interface, determines the analysis window based on real-time load change events, constructs a thermoelectric trajectory point set and divides the load rise and fall periods, forms a continuous dynamic thermoelectric response curve, realizes continuous tracking of the whole process of the connection being heated and disturbed, divides the heating and cooling trajectories through the temperature change trend, extracts the resistance drift amount and the hysteresis loop area, can systematically identify the connection degradation trend and structural fatigue characteristics, further obtains the connection state information generated by the action of thermal stress and thermal cycle asymmetry during the load change period, dynamically adjusts the detection strategy according to the analysis results, realizes early degradation identification and intelligent risk grading of the copper busbar connection state, improves the detection sensitivity and accuracy, and enhances the dynamic perception ability of the healthy evolution process of the connection.

[0119] Embodiment 2: A copper busbar connection state detection method and system, as Figure 2 shown, specifically includes:

[0120] A data acquisition module for the copper busbar connection, which is used to measure the contact resistance at the copper busbar connection during the load change process, and at the same time arrange high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals, eliminate noise through finite difference filtering, and perform registration of the resistance and temperature signals;

[0121] A thermoelectric trajectory determination module, which is used to determine the analysis window and intercept the synchronous data based on real-time monitored load change events, construct a thermoelectric trajectory point set from the synchronous data, and determine the load rise and fall periods to form a continuous thermoelectric dynamic trajectory;

[0122] A load trend determination module, which is used to divide the heating section and the cooling section trajectories according to the temperature change trend, extract the amount of resistance drift during the load increase period in the heating section, determine the deterioration trend of the copper busbar connection, and extract the area of the hysteresis loop in the complete thermal cycle trajectory to perform state determination during the load change;

[0123] A strategy adjustment module, which is used to obtain the thermal stress and the connection state information generated during the thermal cycle during the load change, analyze them, and adjust the detection strategy according to the analysis result of the connection state.

[0124] The above formulas are all calculated by taking the numerical values after dimensionless treatment. Specific dimensionless treatment can adopt various means such as standardization, which will not be elaborated here. The formulas are obtained by collecting a large amount of data for software simulation to get a formula closest to the real situation. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0125] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. 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 the computer, the processes or functions described in the embodiments of the present application 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 computer-readable storage medium. For example, the computer instructions can be transmitted from a website, a computer, a server or a data center to another website, a computer, a server or a data center in a wired or wireless (such as infrared, wireless, microwave, etc.) manner. The computer-readable storage medium can be any available medium that the computer can access or a data storage device such as a server or a data center that includes one or more collections of available media. The available media can be magnetic media (such as floppy disks, ATA hard disks, magnetic tapes), optical media (such as DVDs), or semiconductor media. The semiconductor media can be a solid-state ATA hard disk.

[0126] It should be understood that in various embodiments of the present application, the magnitudes of the sequence numbers of the above processes do not mean the order of execution. The order of execution of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0127] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or in a combination of computer software and electronic hardware. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0128] In several embodiments provided by this application, it should be understood that the disclosed systems, devices, 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 system, 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, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0129] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units. They can be located in one place or 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.

[0130] In addition, the functional units in each embodiment of this application can be integrated in one processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0131] As described above, this is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A method for detecting the connection state of a copper bar, characterized in that, The steps are as follows: During the load change process, measure the contact resistance at the copper bus connection, and simultaneously deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals. Eliminate noise through finite difference filtering and perform registration of resistance and temperature signals. Based on the real-time monitored load change events, determine the analysis window and intercept the synchronous data. Construct a thermoelectric trajectory point set from the synchronous data, and determine the load increase and decrease periods to form a continuous thermoelectric dynamic trajectory. Divide the trajectory into a heating section and a cooling section according to the temperature change trend. Extract the resistance drift amount during the load increase in the heating section to determine the deterioration trend at the copper bus connection, and extract the area of the hysteresis loop in the complete thermal cycle trajectory for state determination during the load change. During the load change period, obtain the thermal stress and connection state information generated during the thermal cycle and analyze it. Adjust the detection strategy according to the analysis results of the connection state.

2. The copper bar connection state detection method according to claim 1, wherein: During the load change process, measure the contact resistance at the copper bus connection, and simultaneously deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals. Eliminate noise through finite difference filtering and perform registration of resistance and temperature signals. The specific process is as follows: Apply a constant current that does not affect the main current of the copper bus at the copper bus, and collect the small voltage drop at both ends of the copper bus connection to determine the copper bus contact resistance. In the copper bus connection joint area, arrange high-precision thermocouples or temperature sensors to collect the original local temperature signal at the copper bus connection joint. The collected original local temperature signal is normalized to obtain the effective temperature. Combine the contact resistance and local temperature data into a unified synchronous data frame. The synchronous data frame includes the copper bus connection contact resistance, the local temperature of the copper bus connection, and a unified timestamp. Use adaptive bidirectional finite difference filtering to process and filter noise for each component in the synchronous data frame.

3. The method for detecting the connection state of copper bars according to claim 2, characterized in that: Based on the real-time monitored load change events, determine the analysis window and intercept the synchronous data. Construct a thermoelectric trajectory point set from the synchronous data, and determine the load increase and decrease periods to form a continuous thermoelectric dynamic trajectory. The specific process is as follows: Detect load change events in real time, intercept the corresponding dynamic response analysis window, and monitor the main current I of the copper busbar main (t), detect the current change rate, and calculate the first derivative dI main / dt. When the following conditions are met, it is determined as the starting point t of the load change s : where δ I is the current change rate threshold; Set the analysis window length T for load variation win , and intercept the data frames collected synchronously within the interval; Extract the smoothed synchronization data at each moment from the analysis window [t s , t s +T win . Among them, is the synchronized resistance sequence, is the synchronized temperature sequence; Construct a thermoelectric trajectory point set with the synchronized resistance sequence as the vertical axis and the synchronized temperature sequence as the horizontal axis: C is a set of resistance and temperature trajectory points used to describe the continuous thermoelectric dynamic response process; Calculate the minimum and maximum values of the temperature sequence within the current load change window, and normalize the minimum and maximum values of the resistance sequence to obtain the trajectory point set of temperature and resistance.

4. A method for detecting the connection state of copper bars according to claim 3, characterized in that: Divide the trajectory into a heating section and a cooling section according to the temperature change trend. The specific steps are as follows: The trajectory point set is divided into a heating section and a cooling section according to the load thermal response cycle. If the temperature difference between the current moment and the next moment is greater than zero and the temperature shows a positive increase, the time period is determined as the heating section. If the temperature difference is less than zero, that is, the temperature drops, it is determined as the cooling section.

5. A method for detecting the connection state of copper bars according to claim 4, characterized in that: Extract the resistance drift amount during the load increase in the heating section to determine the deterioration trend at the copper bus connection, and extract the area of the hysteresis loop in the complete thermal cycle trajectory for state determination during the load change. The specific process is as follows: According to the normalized temperature signal T norm (t i ) calculate the temperature change rate ΔT(t i ) at each moment: ΔT(t i ) = T norm (t i+1 ) - T norm (t i ), where T norm (t i+1 ) represents the moment of t i+1 ; Define the segmented rule: If ΔT(t i ) > 0, it is determined as the load rising section; if ΔT(t i ) < 0, it is determined as the load falling section; Divide the trajectory point set according to the segmentation rule to obtain the load increase section set and the load decrease section set. Analyze the trajectories of the load increase period and the load decrease period extracted by segmentation to determine the response characteristics of different stages of the performance of the copper bus connection with respect to thermal stress changes. In the set of load rising segments, extract the normalized resistance signal R norm (t i ), and define the resistance drift as an integral measure of the resistance change during the load rise; The definition of the resistance drift amount is as follows: where T up is the load rising duration, which is obtained by the difference between the start and end times of the load rising section; t s , t e are the start and end times of the load rising section respectively; Construct a hysteresis loop profile with the load rising section and the load falling section in the trajectory point set as the boundaries, and use the discrete curve integral method to calculate the hysteresis area A enclosed by the hysteresis loop H ; The set of points obtained by arranging the trajectory loop in ascending order of temperature is taken as the hysteresis area: where N is the total number of trajectory points.

6. A method for detecting the connection state of copper bars according to claim 5, characterized in that: During the load change period, obtain the thermal stress and connection state information generated during the thermal cycle and analyze it. The specific process is as follows: Obtain the thermal stress and the connection state information generated during the thermal cycle. The connection state information includes resistance drift information and hysteresis response information. The resistance drift information includes the dynamic index of thermal stress deterioration, and the hysteresis response information includes the thermal cycle asymmetric stability index; The dynamic index of thermal stress deterioration represents the resistance change of the copper bus connection caused by thermal stress during the load increase; The thermal cycle asymmetric stability index represents the change of the asymmetry and stability of the thermoelectric behavior at the connection of the copper bus after experiencing a complete load heating and cooling cycle; Compare the dynamic index of thermal stress deterioration with the dynamic threshold of thermal stress deterioration, and compare the thermal cycle asymmetric stability index with the thermal cycle asymmetric stability threshold.

7. A method for detecting the connection state of copper bars according to claim 6, characterized in that: Adjust the detection strategy according to the analysis result of the connection state. The specific process is as follows: Compare the dynamic index of thermal stress deterioration with the dynamic threshold of thermal stress deterioration, and compare the thermal cycle asymmetric stability index with the thermal cycle asymmetric stability threshold. Divide it into four cases according to the comparison results and make different strategy adjustments; In the first case, if the dynamic index of thermal stress deterioration is less than or equal to the dynamic threshold of thermal stress deterioration, and at the same time the thermal cycle asymmetric stability index is also less than or equal to the thermal cycle asymmetric stability threshold, then maintain the regular inspection cycle, monitor according to the normal detection plan, and there is no need to increase the maintenance frequency or take additional intervention measures; In the second case, if the dynamic index of thermal stress deterioration is greater than the dynamic threshold of thermal stress deterioration, while the thermal cycle asymmetric stability index is still less than or equal to the thermal cycle asymmetric stability threshold, then shorten the subsequent detection cycle, increase the drift trend tracking, and arrange a local connection inspection; In the third case, if the dynamic index of thermal stress deterioration is less than or equal to the dynamic threshold of thermal stress deterioration, while the thermal cycle asymmetric stability index is greater than the thermal cycle asymmetric stability threshold, then take accelerated inspection measures to check the connection crimping state, bolt tightening condition and physical state of the contact interface; In the fourth case, if the dynamic index of thermal stress deterioration is greater than the dynamic threshold of thermal stress deterioration, and the thermal cycle asymmetric stability index is greater than the thermal cycle asymmetry stability, then immediately arrange a shutdown for maintenance, check and replace the severely deteriorated connection parts, and simultaneously conduct a synchronous investigation on the surrounding copper bus connection units.

8. A copper busbar connection state detection method system for implementing the copper busbar connection state detection method according to any one of claims 1-7, characterized in that, Including: The data acquisition module at the copper bus connection is used to measure the contact resistance at the copper bus connection during the load change process, and at the same time deploy high-precision temperature sensors in the connection area to synchronously collect local temperature rise signals, eliminate noise through finite difference filtering, and perform registration of resistance and temperature signals; The thermoelectric trajectory determination module is used to determine the analysis window and intercept the synchronous data based on the real-time monitored load change events, construct a set of thermoelectric trajectory points from the synchronous data, and determine the load rise and fall periods to form a continuous thermoelectric dynamic trajectory; The load trend determination module is used to divide the temperature change trend into the rising temperature section and the falling temperature section trajectories, extract the resistance drift amount during the load increase in the rising temperature section, determine the deterioration trend of the copper bus connection, and extract the hysteresis loop area in the complete thermal cycle trajectory to perform the state determination during the load change; A strategy adjustment module, which is used to obtain connection state information generated during thermal stress and thermal cycling during load changes, analyze it, and adjust the detection strategy according to the analysis results of the connection state.

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