Intelligent monitoring method for contact resistance fault of ring main unit

Abstract

The invention relates to the technical field of power equipment, in particular to an intelligent monitoring method for a contact resistance fault of a ring main unit, which comprises the following steps of: periodically acquiring current data, calculating average current and drawing a periodic average current curve, converting discrete current data into a continuous trend curve, and intuitively reflecting the dynamic change of the contact resistance, for example, determining the contact resistance fault of the ring main unit. When the contact resistance is increased, the current tends to decrease along with the period, the absolute value of the curve slope changes along with the period, the change can be captured in real time through the curve, compared with static data acquisition, the method can accurately describe the process of the resistance change, a more comprehensive trend basis is provided for follow-up analysis, and the method is suitable for popularization and application. The problem that an existing method is insufficient in current data application is solved. By calculating the absolute value of the curve slope and comparing the absolute value with the preset absolute value, the strong operation fault tendency or the weak operation fault tendency can be determined at the initial stage of the poor contact problem.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment, and in particular to an intelligent monitoring method for contact resistance fault of a ring network cabinet. Background Art

[0002] Ring main unit (RMU) units, as key equipment in power distribution networks, are widely used in urban distribution networks, industrial parks, and other scenarios. Their core function is to provide power supply, disconnection, and protection for distribution lines. The contact condition of the wiring terminals within the RMU directly impacts the stability of power transmission. Poor contact at the terminals increases contact resistance, leading to localized Joule heat accumulation and overheating. Long-term operation can cause insulation degradation, equipment burnout, and even power outages, posing a serious threat to the safe operation of the power system.

[0003] At present, the monitoring of contact resistance faults in ring network cabinets mainly relies on two methods: one is manual regular inspections, which use infrared thermometers to detect the temperature of the terminal. This method has problems such as poor real-time performance, high labor intensity, and susceptibility to human experience, making it difficult to capture sudden poor contact faults; the other is traditional automatic monitoring systems, which mostly collect temperature data through built-in temperature sensors, but they can only passively feedback overheating results and cannot predict the contact resistance change trend in advance. It is also difficult to distinguish different fault causes such as insufficient contact pressure, oxidation or contamination of the terminal surface, resulting in insufficient targeted fault handling. Existing methods make it difficult to dynamically capture the contact resistance change trend through current data, and cannot determine the type of operating fault tendency in advance, resulting in delayed fault response.

[0004] Chinese patent application number: CN202510109535.0 discloses an intelligent ring network cabinet and a monitoring method for an intelligent ring network cabinet, including a circuit breaker energy storage spring, a trip spring, a tripping coil, and an energy storage motor, and also includes a first pressure sensor, a second pressure sensor, a Hall sensor, and a data processing unit. The first pressure sensor and the second pressure sensor are respectively connected to the circuit breaker energy storage spring and the trip spring. The first pressure sensor collects pressure information of the circuit breaker energy storage spring and transmits the pressure information to the data processing unit, the second pressure sensor collects pressure information of the trip spring and transmits the pressure information to the data processing unit, and the Hall sensor collects action current information of the tripping coil and the energy storage motor and transmits the action current information to the data processing unit. This invention can detect faults in time at the early stage so as to eliminate the faults in time and ensure the continuity of power supply, and can accurately determine the fault location.

[0005] However, the prior art still has the following problems: Existing methods make it difficult to dynamically capture the contact resistance change trend through current data, and are unable to determine the type of operating fault tendency in advance, resulting in delayed fault response. Summary of the Invention

[0006] To this end, the present invention provides an intelligent monitoring method for contact resistance faults in ring network cabinets to overcome the problem in the prior art that it is difficult to dynamically capture the contact resistance change trend through current data, and it is impossible to determine the type of operating fault tendency in advance, resulting in delayed fault response.

[0007] To achieve the above objectives, the present invention provides an intelligent monitoring method for contact resistance faults in ring main units. The method comprises: Step S1, periodically collecting current data information at each terminal in the cable room, calculating the average current value of each cycle, and drawing a cycle-average current curve; Step S2, calculating the slope of the curve in the current detection period, and determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve; Step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit, including: Determine that the operating condition of the ring main unit is unqualified and the reason for the unqualified condition is the existence of poor contact terminals, adjust the contact pressure based on the slope of the curve, and analyze whether to correct the contact pressure based on the proportion of the number of abnormal terminals. Or, determine whether the operating status of the ring main unit is qualified; Step S4: output the analysis results.

[0008] Furthermore, in step S2, determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve includes: If the absolute value of the slope of the curve is greater than or equal to the preset absolute value, the operation fault tendency type of the ring main unit is determined to be a strong operation fault tendency; If the absolute value of the slope of the curve is less than the preset absolute value, it is determined that the operation fault tendency type of the ring main unit is a weak operation fault tendency.

[0009] Furthermore, in step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit includes: If the operation fault tendency type of the ring main unit is a strong operation fault tendency, it is determined that the operation condition of the ring main unit is unqualified and the reason for the unqualified condition is the presence of a poor contact terminal, and the contact pressure is adjusted based on the slope of the curve, and whether the contact pressure should be corrected is analyzed based on the proportion of the number of abnormal terminals; If the operation fault tendency type of the ring main unit is a weak operation fault tendency, the operation condition of the ring main unit is determined to be qualified.

[0010] Furthermore, adjusting the contact pressure based on the slope of the curve includes: The difference between the absolute value of the slope of the curve and the preset absolute value is calculated to obtain the absolute difference, wherein the increase in the contact pressure is positively correlated with the absolute difference.

[0011] Furthermore, when the adjustment of the contact pressure is completed, analyzing whether to correct the contact pressure based on the proportion of the number of abnormal terminals includes: Filter abnormal terminals and count the number of abnormal terminals. Calculate the ratio of the number of abnormal terminals to the total number of terminals to obtain the abnormal proportion. If the abnormality ratio is greater than or equal to the preset abnormality ratio, it is determined that the contact pressure is not to be corrected; If the abnormality ratio is less than the preset abnormality ratio, it is determined that the contact pressure is to be corrected, wherein the reduction amount of the contact pressure during the correction process is negatively correlated with the abnormality ratio.

[0012] Furthermore, when the adjustment of the contact pressure is completed, the current difference between the preset current and the actual current at each terminal is calculated, and the contact pressure for a single terminal is corrected based on the current difference, wherein the increase in contact pressure is positively correlated with the current difference.

[0013] Furthermore, when the adjustment of the contact pressure is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring network cabinet is unqualified, the contact pressure is repeatedly adjusted based on the re-acquired curve slope, and it is determined that the reason for the unqualified operating condition of the ring network cabinet is that the terminal surface is unqualified.

[0014] Furthermore, when the terminal surface is determined to be unqualified, the curve data in the current detection cycle is extracted, the curve integral value is calculated, and the processing method is determined based on the curve integral value, including: If the curve integral is less than or equal to the preset curve integral, it is determined that a connector replacement notification signal is issued; If the curve integral is greater than the preset curve integral, it is determined to adjust the heat dissipation operating power.

[0015] Furthermore, when determining to adjust the heat dissipation operating power, the integral difference between the curve integral and the preset curve integral is calculated, wherein the increase in the heat dissipation operating power is positively correlated with the integral difference.

[0016] Furthermore, when the adjustment for the heat dissipation operating power is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring main unit is unqualified, a connector replacement notification signal is issued.

[0017] Compared with the prior art, the beneficial effect of the present invention lies in that, in the present invention, by periodically collecting current data, calculating the average current, and drawing the process of the periodic average current curve, the discrete current data is converted into a continuous trend curve, which intuitively reflects the dynamic changes of the contact resistance. For example, when the contact resistance increases, the current will show a downward trend with the cycle, and the absolute value of the slope of the curve will change accordingly. This change can be captured in real time through the curve. Compared with static data collection, this method can accurately characterize the process of resistance change, provide a more comprehensive trend basis for subsequent analysis, and solve the problem of insufficient application of current data in existing methods; in the present invention, by calculating the absolute value of the slope of the curve and comparing it with the preset absolute value, the strong operation fault tendency or weak operation fault tendency can be clearly identified at the early stage of the poor contact problem. When the absolute value of the slope is ≥ the preset value, the strong tendency that may cause a serious fault is locked in advance. At this time, although the contact resistance has not reached the fault critical value, the change rate is already abnormal. Early intervention can avoid the deterioration of the fault. This trend prediction mode moves the fault judgment node from after the fault occurs to the fault incubation period, solving the core pain point of the existing method's response lag.

[0018] Furthermore, the present invention takes into account that existing methods often lack clear risk grading standards, and either over-process slight current fluctuations (resulting in increased equipment losses) or react slowly to significant abnormal signals (missing the optimal opportunity for intervention). In step S2, the fault tendency is clearly divided into two categories, "strong operation fault tendency" and "weak operation fault tendency", by "comparing the absolute value of the curve slope with the preset absolute value". When the absolute value of the slope is ≥ the preset value, the high-risk state is directly locked (such as a rapid increase in contact resistance); when the absolute value of the slope is < the preset value, it is judged to be a low-risk state (such as normal fluctuation). This clear definition of "either this or that" avoids ambiguous risk judgment, prevents excessive intervention in slight abnormalities, and ensures that serious risks are identified in a timely manner, thereby achieving accurate graded control of fault risks.

[0019] Furthermore, the present invention takes into account that the essence of poor contact is increased contact resistance, and contact pressure is a key factor affecting resistance. Insufficient pressure will lead to increased resistance, and excessive pressure may cause deformation of the terminal. The logic of adjusting the contact pressure based on the slope of the curve in step S3 calculates the absolute difference (the difference between the absolute value of the curve slope and the preset absolute value) so that the pressure increase is positively correlated with the degree of abnormality. This dynamic adjustment mechanism avoids the limitations of "fixed value adjustment": when the abnormality is slight (small difference), a small increase in pressure can improve contact; when the abnormality is significant (large difference), a larger increase in pressure can be used to quickly reduce resistance. Compared with the traditional method of "uniformly increasing fixed pressure", this method not only ensures the repair effect, but also prevents excessive adjustment from causing secondary damage to the equipment, thereby realizing precise repair of "on-demand adjustment".

[0020] Furthermore, the present invention takes into account that when the proportion of abnormal terminals is greater than or equal to the preset abnormal proportion, it means that there may be systemic problems, such as overall failure of the pressure device, general aging of the terminals, etc. At this time, if the contact pressure is still corrected, it will not only fail to solve the fundamental problem, but may also aggravate equipment loss due to repeated adjustments. The judgment of not correcting in the step can terminate the invalid pressure adjustment in time, guide the operation and maintenance personnel to turn to investigating systemic causes (such as checking whether the pressure device is malfunctioning), avoid wasting resources on surface adjustments, and improve the directionality and efficiency of fault handling.

[0021] Furthermore, the present invention takes into account that in a ring main unit, most of the terminals are usually in normal operating state (the current difference is close to 0). If the pressure of all terminals is uniformly adjusted, the normal terminals will be subjected to unnecessary high pressure, accelerating their aging and deformation (such as copper terminals may undergo plastic deformation due to long-term overvoltage). In the steps, only the terminals with current differences are targeted for adjustment, and the normal terminals maintain the original pressure, avoiding the loss of normal components caused by "indiscriminate adjustment".

[0022] Furthermore, the present invention takes into account that the greater the contact pressure, the better: exceeding the compressive limit of the terminal material (such as more than 750N for the copper terminal) will cause deformation and cracking, and overly frequent adjustments (such as more than 4 times) will accelerate the mechanical loss of the pressure device. The rule of "adjusting until the critical value is reached or the number of adjustments reaches the critical value and stops" in the step limits the adjustment behavior from the aspects of physical limits and mechanical life through the dual constraints of "pressure critical value" and "number critical value".

[0023] Furthermore, the present invention takes into account that the degree of harm caused by unqualified terminal surfaces is not completely consistent. Slight oxidation may only cause a slow increase in contact resistance, while severe ablation may cause local overheating in a short period of time. In the step, the curve integral value is calculated (reflecting the cumulative effect of current in a certain period, which is positively correlated with the heat generation) and compared with the preset curve integral, and the surface faults are divided into "low urgency" and "high urgency" categories. For surface faults with an integral ≤ preset value (such as slight oxidation), it will not cause serious risks in the short term. At this time, a replacement notice is issued instead of immediate shutdown for maintenance, which can avoid production interruptions caused by emergency shutdowns (such as factory production line shutdowns and data center downtime). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Flowchart of the intelligent monitoring method for contact resistance fault of ring main unit; Figure 2 A flow chart for determining the type of operating fault tendency of the ring main unit; Figure 3 A flow chart for determining the analysis method for ring main units. DETAILED DESCRIPTION

[0025] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0026] It should be noted that the data in this embodiment are obtained by comprehensive analysis and evaluation of the historical data of the six months before the current determination and the corresponding historical determination results by the system of the present invention. It can be understood by those skilled in the art that the system of the present invention can determine the above parameters for each of the above parameters by selecting the value with the highest proportion as the preset standard parameter based on the data distribution, using weighted summation to use the obtained value as the preset standard parameter, substituting each historical data into a specific formula and using the value obtained by the formula as the preset standard parameter, or other selection methods, as long as the system of the present invention can clearly define the different specific situations in the single determination process through the obtained values.

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0029] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0030] See also Figure 1 As shown, it is a flow chart of the intelligent monitoring method for ring network cabinet contact resistance fault.

[0031] The intelligent monitoring method for contact resistance fault of a ring main unit provided in this embodiment includes: Step S1, periodically collecting current data information at each terminal in the cable room, calculating the average current value of each cycle, and drawing a cycle-average current curve; Step S2, calculating the slope of the curve in the current detection period, and determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve; Step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit, including: Determine that the operating condition of the ring main unit is unqualified and the reason for the unqualified condition is the existence of poor contact terminals, adjust the contact pressure based on the slope of the curve, and analyze whether to correct the contact pressure based on the proportion of the number of abnormal terminals. Or, determine whether the operating status of the ring main unit is qualified; Step S4: output the analysis results.

[0032] In the present invention, by periodically collecting current data, calculating the average current, and drawing the cycle average current curve, the discrete current data is converted into a continuous trend curve, which intuitively reflects the dynamic changes of contact resistance. For example, when the contact resistance increases, the current will show a downward trend with the cycle, and the absolute value of the slope of the curve will change accordingly. This change can be captured in real time through the curve. Compared with static data collection, this method can accurately characterize the process of resistance change, provide a more comprehensive trend basis for subsequent analysis, and solve the problem of insufficient application of current data in existing methods; in the present invention, by calculating the absolute value of the slope of the curve and comparing it with the preset absolute value, the strong operation fault tendency or weak operation fault tendency can be clearly identified at the early stage of the poor contact problem. When the absolute value of the slope is ≥ the preset value, the strong tendency that may cause serious faults is locked in advance. At this time, although the contact resistance has not reached the fault critical value, the change rate is already abnormal. Early intervention can avoid the deterioration of the fault. This trend prediction mode moves the fault judgment node from after the fault occurs to the fault incubation period, solving the core pain point of the existing method's response lag.

[0033] See also Figure 2 As shown, it is a flow chart for determining the type of operation fault tendency of the ring network cabinet.

[0034] Specifically, in step S2, determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve includes: If the absolute value of the slope of the curve is greater than or equal to the preset absolute value, the operation fault tendency type of the ring main unit is determined to be a strong operation fault tendency; If the absolute value of the slope of the curve is less than the preset absolute value, it is determined that the operation fault tendency type of the ring main unit is a weak operation fault tendency.

[0035] Specifically, in this embodiment, the preset absolute value can be determined in the following way: extract the cycle-average current curve slope data set of the ring network cabinet of the same model and the same working condition under normal operating state (no poor contact fault) within a preset time window (such as 6 months), calculate its statistical characteristics (such as mean, 95% percentile), and use the 95% percentile as the initial reference benchmark (reflecting the maximum slope fluctuation under most normal scenarios); adjust according to the operating load (such as peak / off-peak) and ambient temperature (high temperature can easily aggravate contact resistance changes) of the ring network cabinet: when the load is peak or the ambient temperature exceeds 35°C, the initial benchmark value is increased by 10%-15%; under low load or normal temperature environment, the benchmark value is reduced by 5%-10%; set a minimum threshold (such as a fixed value) to ensure that significant anomalies can be effectively identified even in low fluctuation scenarios; and set a maximum threshold (such as not more than 2 times the initial benchmark) to avoid misjudgment caused by excessive sensitivity.

[0036] The present invention takes into account that existing methods often lack clear risk grading standards, and either over-process slight current fluctuations (resulting in increased equipment losses) or react slowly to significant abnormal signals (missing the best opportunity for intervention). In step S2, the fault tendency is clearly divided into two categories, "strong operation fault tendency" and "weak operation fault tendency", by "comparing the absolute value of the curve slope with the preset absolute value". When the absolute value of the slope is ≥ the preset value, the high-risk state is directly locked (such as a rapid increase in contact resistance); when the absolute value of the slope is < the preset value, it is judged to be a low-risk state (such as normal fluctuations). This clear definition of "either this or that" avoids ambiguous risk judgment, prevents excessive intervention in slight abnormalities, and ensures that serious risks are identified in a timely manner, thereby realizing accurate graded control of fault risks.

[0037] See also Figure 3 As shown, it is a decision flow chart for determining the analysis method for the ring main unit.

[0038] Specifically, in step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit includes: If the operation fault tendency type of the ring main unit is a strong operation fault tendency, it is determined that the operation condition of the ring main unit is unqualified and the reason for the unqualified condition is the presence of a poor contact terminal, and the contact pressure is adjusted based on the slope of the curve, and whether the contact pressure should be corrected is analyzed based on the proportion of the number of abnormal terminals; If the operation fault tendency type of the ring main unit is a weak operation fault tendency, the operation condition of the ring main unit is determined to be qualified.

[0039] Specifically, adjusting the contact pressure based on the slope of the curve includes: The difference between the absolute value of the slope of the curve and the preset absolute value is calculated to obtain the absolute difference, wherein the increase in the contact pressure is positively correlated with the absolute difference.

[0040] Specifically, in this embodiment, it is assumed that the preset absolute value of a ring network cabinet determined by calculation is 0.33A / cycle, and the absolute value of the slope of the curve in the current detection cycle is 0.5A / cycle; first calculate the absolute difference: 0.5A / cycle-0.33A / cycle=0.17A / cycle; the basic contact pressure set by the ring network cabinet is 500N, and the preset adjustment rule of "every absolute difference of 0.1A / cycle corresponds to an increase of 50N contact pressure" is set (reflecting a positive correlation); according to the absolute difference of 0.17A / cycle, the contact pressure needs to be increased by: (0.17 / 0.1)×50N=85N; therefore, the adjusted contact pressure is: 500N+85N=585N; through this adjustment method, the contact pressure is dynamically increased with the abnormality of the slope of the current curve, and the problem of poor contact is improved in a targeted manner.

[0041] The present invention takes into account that the essence of poor contact is increased contact resistance, and contact pressure is a key factor affecting resistance. Insufficient pressure will lead to increased resistance, and excessive pressure may cause deformation of the terminal. In step S3, the logic of adjusting the contact pressure based on the slope of the curve is used to calculate the absolute difference (the difference between the absolute value of the curve slope and the preset absolute value) so that the pressure increase is positively correlated with the degree of abnormality. This dynamic adjustment mechanism avoids the limitations of "fixed value adjustment": when the abnormality is slight (small difference), a small increase in pressure can improve contact; when the abnormality is significant (large difference), a larger increase in pressure is used to quickly reduce resistance. Compared with the traditional method of "uniformly increasing fixed pressure", this method not only ensures the repair effect, but also prevents excessive adjustment from causing secondary damage to the equipment, thereby realizing precise repair of "on-demand adjustment".

[0042] Specifically, when the adjustment of the contact pressure is completed, analyzing whether to correct the contact pressure based on the proportion of the number of abnormal terminals includes: Filter abnormal terminals and count the number of abnormal terminals. Calculate the ratio of the number of abnormal terminals to the total number of terminals to obtain the abnormal proportion. If the abnormality ratio is greater than or equal to the preset abnormality ratio, it is determined that the contact pressure is not to be corrected; If the abnormality ratio is less than the preset abnormality ratio, it is determined that the contact pressure is to be corrected, wherein the reduction amount of the contact pressure during the correction process is negatively correlated with the abnormality ratio.

[0043] Specifically, in this embodiment, the preset abnormality ratio can be determined by collecting operating data of ring main units of the same model and operating conditions over the past 3-5 years, screening the ratio of abnormal terminal numbers when faults are caused by poor contact, and calculating their statistical distribution (such as mean, 75% percentile, etc.). If the abnormality ratio in most fault cases is concentrated in the range of 20%-30%, this range is used as the initial reference range. For ring main units with a small total number of terminals (such as ≤10), the preset abnormality ratio can be reduced by 5%-10% because a single abnormal terminal has a more significant impact on the overall situation. For ring main units with a large total number of terminals (such as ≥30), the preset abnormality ratio can be appropriately increased by 5%-10% to avoid oversensitivity. In critical load scenarios (such as hospitals and data centers), where ring main units require higher stability, the preset abnormality ratio can be set to a lower value (such as 15%). In ordinary industrial scenarios, it can be set to a higher value (such as 25%). The final preset abnormality ratio must meet a minimum threshold of ≥5% (to avoid misjudgment due to a very small number of abnormalities) and a maximum threshold of ≤40% (to prevent blind correction when a large number of abnormalities are present).

[0044] Specifically, in this embodiment, it is assumed that the total number of terminals in a ring main unit in a certain ordinary industrial scenario is 20, the preset abnormal proportion is 20%, the contact pressure after basic adjustment is 585N, and the preset correction rule is that for every 5% decrease in the abnormal proportion, the contact pressure reduction increases by 20N. The number of abnormal terminals: 3 (3 / 20=15%); the difference from the preset abnormal proportion: 20%-15%=5%; the calculation of the contact pressure reduction: since the difference is 5%, according to the rule, the reduction is 20N; the corrected contact pressure: 585N-20N=565N; at this time, the abnormal proportion is 5% lower than the preset value. Appropriately reducing the contact pressure can not only ensure the contact effect of the abnormal terminal, but also avoid damage to the normal terminal due to excessive pressure.

[0045] The present invention takes into account that when the proportion of abnormal terminals is greater than or equal to the preset abnormal proportion, it means that there may be systemic problems, such as overall failure of the pressure device, general aging of the terminals, etc. At this time, if the contact pressure is still corrected, it will not only fail to solve the fundamental problem, but may also aggravate equipment loss due to repeated adjustments. The judgment of not correcting in the steps can terminate the invalid pressure adjustment in time, guide the operation and maintenance personnel to turn to investigating systemic causes (such as checking whether the pressure device is malfunctioning), avoid wasting resources on surface adjustments, and improve the directionality and efficiency of fault handling.

[0046] Specifically, when the adjustment of the contact pressure is completed, the current difference between the preset current and the actual current at each terminal is calculated, and the contact pressure for a single terminal is corrected based on the current difference, wherein the increase in contact pressure is positively correlated with the current difference.

[0047] Specifically, in this embodiment, if the above determination does not require correction, the adjusted contact pressure parameter is used as the initial value; if the above determination requires correction, the corrected contact pressure parameter is used as the initial value, and then analysis is performed on whether correction is performed based on the current difference.

[0048] Specifically, in this embodiment, assuming a ring main unit in a common industrial scenario, the total number of terminals is 20. After adjustment in step S3 and correction of the abnormality ratio, the overall contact pressure is 565N (refer to the correction result of the 15% abnormality ratio in the previous article), the preset current of each terminal (the standard current value during normal operation) is 100A, and the preset correction rule is "increase the contact pressure by 5N for every 1A current difference"; the actual current of a certain terminal: 97A; current difference calculation: preset current - actual current = 100A - 97A = 3A (the actual current is lower than the preset value, and there is a tendency for poor contact); contact pressure increase: 3A × 5N / A = 15N; the contact pressure of a single terminal after correction: 565N + 15N = 580N; the current of this terminal is slightly lower than the preset value, and a slight increase in contact pressure can improve the contact state and avoid further current drop due to excessive contact resistance.

[0049] The present invention takes into account that in a ring main unit, most terminals are usually in normal operating state (the current difference is close to 0). If the pressure of all terminals is uniformly adjusted (such as an overall increase of 85N), the normal terminals will be subjected to unnecessary high pressure, accelerating their aging and deformation (such as copper terminals may undergo plastic deformation due to long-term overvoltage). In the steps, only the terminals with current difference are targeted for adjustment, and the normal terminals maintain the original pressure (such as 565N), avoiding the loss of normal components due to "indiscriminate adjustment".

[0050] Specifically, when the adjustment of the contact pressure is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring network cabinet is unqualified, the contact pressure is repeatedly adjusted based on the re-acquired curve slope, and it is determined that the reason for the unqualified operating condition of the ring network cabinet is that the terminal surface is unqualified.

[0051] Specifically, in this embodiment, if it is determined that the contact pressure needs to be repeatedly adjusted, the contact pressure is repeatedly adjusted until it reaches a critical value or the adjustment number reaches a critical value and then stops.

[0052] Specifically, in this embodiment, if the above determination does not require correction, the adjusted contact pressure parameter is used as the initial value; if the above determination requires correction, the corrected contact pressure parameter is used as the initial value, and steps S1-S3 are repeated.

[0053] Specifically, in this embodiment, the critical value of the contact pressure can be determined in the following manner: based on the material of the terminal (such as copper, aluminum or alloy), refer to the compressive strength parameter of the material, for example, the compressive strength of the copper terminal is generally 300-400MPa, and the maximum tolerable pressure is calculated in combination with its contact area (pressure = compressive strength × contact area); through simulation experiments, the fatigue damage data of the terminal after repeated pressure is obtained, and 80% of the maximum pressure value before fatigue damage is taken as the safety critical reference; statistics are collected on cases where the terminal of the same model of ring network cabinet is deformed or cracked due to excessive pressure, and the pressure value at the time of failure is used as the upper limit of the critical value; in scenarios with frequent vibration (such as industrial workshops), the critical value is reduced by 10%-15%; in stable environments (such as substations), the basic critical value can be maintained; taking a copper terminal ring network cabinet (20 terminals) in an ordinary industrial scenario as an example: the contact area of ​​the copper terminal is 100mm² (0.0001m²), and the compressive strength is taken as , then the theoretical maximum bearing pressure = ; Referring to historical data, this type of ring main unit is prone to slight deformation of the terminal when the pressure exceeds 800N. The specific process of fatigue limit correction is as follows: through fatigue testing, the fatigue limit pressure of this type of terminal is obtained to be 850N (that is, the critical value at which no plastic deformation will occur under this pressure for a long time); considering the engineering safety margin (usually 90% of the fatigue limit), it is calculated that 850N×90%=765N; combined with the boundary condition of "slight deformation at 800N" in historical failure data, the contact pressure critical value is finally determined to be 750N (which is lower than the failure critical value of 800N and meets the safety requirements after fatigue limit correction).

[0054] Specifically, in this embodiment, the critical value of the number of adjustments can be determined by the following method: among the same type of poor contact failures, the maximum number of adjustments required for cases that can be repaired by pressure adjustment is statistically analyzed, which is usually 3-5 times (after exceeding this number, the effect of pressure adjustment on improving contact decreases significantly); considering the mechanical life of the ring network cabinet pressure regulating device, if the design life of the device is 200 adjustments, take 1 / 50 of it (i.e., 4 times) as the critical value to avoid excessive wear and tear of the device; combined with the operation and maintenance cost, when the number of adjustments exceeds a certain value (such as 5 times), the cost of continuing to adjust is higher than the cost of directly repairing the terminal, and this value is the critical value at this time; taking a copper terminal ring network cabinet (20 terminals) in a common industrial scenario as an example: among the poor contact failures of the same model of ring network cabinet, 90% of the repairable cases are solved by adjustments within 3 times, and the repair rate drops to less than 10% after more than 4 adjustments; the mechanical life of the pressure regulating device is 200 times, and 1 / 50 of it is taken as 4 times; the critical value of the number of adjustments is comprehensively determined to be 4 times.

[0055] The present invention takes into account that the greater the contact pressure, the better: exceeding the compressive limit of the terminal material (such as more than 750N for the copper terminal) will cause deformation and cracking, and overly frequent adjustments (such as more than 4 times) will accelerate the mechanical loss of the pressure device. The rule of "adjusting until the critical value is reached or the number of adjustments reaches the critical value and stops" in the step limits the adjustment behavior from the aspects of physical limits and mechanical life through the dual constraints of "pressure critical value" and "number critical value".

[0056] Specifically, when determining that the terminal surface is unqualified, the curve data within the current inspection cycle is extracted, the curve integral value is calculated, and the processing method is determined based on the curve integral value, including: If the curve integral is less than or equal to the preset curve integral, it is determined that a connector replacement notification signal is issued; If the curve integral is greater than the preset curve integral, it is determined to adjust the heat dissipation operating power.

[0057] Specifically, in this embodiment, the preset curve integral can be determined in the following manner: the curve integral value reflects the cumulative effect of the current within a certain period (positively correlated with the heat generation), and the corresponding relationship of "curve integral value-terminal temperature" is established through experiments. For example, for every 100A cycle increase in the integral value, the corresponding terminal temperature increases by 5°C; based on the heat resistance parameters of the insulation layer and metal material on the terminal surface (such as the maximum temperature resistance of the insulation layer is 105°C), combined with the temperature correlation relationship, the critical curve integral value is reversed; the curve integral data of the same model ring network cabinet when it fails due to terminal surface problems (such as oxidation and ablation) is collected, and 90% of the integral value before the fault is taken as the initial reference threshold; in high temperature environments (such as outdoor cabinets in summer), the preset curve integral is reduced by 10%-20%; in low temperature environments (such as air-conditioned rooms), it can be increased by 5%-10%; the curve integral value is calculated as follows: a definite integral is performed on the cycle-average current curve within the current detection period, and the integration interval is from the start time to the end time of the current detection period (assuming the number of cycles is t and the average current is I(t)), and the integration formula is: curve integral value = ;in, is the starting period of the current detection period, is the end period of the current detection period, I(t) is the average current value of the tth period, and the unit of the integral result is ' ' (i.e. the product of the average current and the number of cycles).

[0058] Specifically, in this embodiment, the specific calculation method for inferring the critical curve integral value based on the temperature correlation relationship is: establish a functional relationship between the temperature T and the curve integral value S through experiments: (where k and b are experimental fitting constants, obtained by fitting the temperature measured data of the same type of ring network cabinet at different integral values); according to the maximum tolerance temperature T_max of the insulation layer of the terminal (such as 105℃), substitute the above function to infer the critical curve integral value S_critical, that is, S_critical=(T_max-b) / k; for example, if the experimental fitting results in k=0.05℃ / ( ), b = 30 ° C, T_max = 105 ° C, then cycle.

[0059] The present invention takes into account that the degree of harm caused by unqualified terminal surfaces is not completely consistent. Slight oxidation may only cause a slow increase in contact resistance, while severe ablation may cause local overheating in a short period of time. In the step, the curve integral value is calculated (reflecting the cumulative effect of current in a certain period, which is positively correlated with the heat generation) and compared with the preset curve integral. The surface faults are divided into "low urgency" and "high urgency" categories. For surface faults with an integral ≤ preset value (such as slight oxidation), they will not cause serious risks in the short term. At this time, a replacement notice is issued instead of immediate shutdown for maintenance, which can avoid production interruptions caused by emergency shutdowns (such as factory production line shutdowns and data center downtime).

[0060] Specifically, when determining to adjust the heat dissipation operating power, the integral difference between the curve integral and the preset curve integral is calculated, wherein the increase in the heat dissipation operating power is positively correlated with the integral difference.

[0061] Specifically, in this embodiment, for example, a copper terminal ring main unit (20 terminals) in a common industrial scenario, the preset curve integral is cycle (refer to the results determined above), the basic cooling power of the ring network cabinet is 1000W, and the preset adjustment rule is "per The integral difference of the period corresponds to a 10% increase in heat dissipation power". The example is as follows: The integral difference is Cycle; Curve integral value within the current detection cycle: Period; integral difference calculation: cycle- Period = cycle; cooling operation power increase: according to the rules, The corresponding cycle increases by 10%, that is, 1000W×10%=100W; the adjusted cooling operating power is: 1000W+100W=1100W; at this time, the integral difference is small, and the heat generation slightly exceeds the safe range. A slight increase in the cooling power can control the temperature within the tolerance range of the insulation layer (for example, from 86°C to 82°C).

[0062] Specifically, when the adjustment for the heat dissipation operating power is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring main unit is unqualified, a connector replacement notification signal is issued.

[0063] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An intelligent monitoring method for contact resistance fault of a ring main unit, characterized in that: include: Step S1, periodically collecting current data information at each terminal in the cable room, calculating the average current value of each cycle, and drawing a cycle-average current curve; Step S2, calculating the slope of the curve in the current detection period, and determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve; Step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit, including: Determine that the operating condition of the ring main unit is unqualified and the reason for the unqualified condition is the existence of poor contact terminals, adjust the contact pressure based on the slope of the curve, and analyze whether to correct the contact pressure based on the proportion of the number of abnormal terminals. Or, determine whether the operating status of the ring main unit is qualified; Step S4: output the analysis results.

2. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 1, characterized in that: In step S2, determining the operation fault tendency type of the ring main unit based on the absolute value of the slope of the curve includes: If the absolute value of the slope of the curve is greater than or equal to the preset absolute value, the operation fault tendency type of the ring main unit is determined to be a strong operation fault tendency; If the absolute value of the slope of the curve is less than the preset absolute value, it is determined that the operation fault tendency type of the ring main unit is a weak operation fault tendency.

3. The intelligent monitoring method for contact resistance fault of ring main unit according to claim 2, characterized in that: In step S3, determining an analysis method for the ring main unit based on the operation fault tendency type of the ring main unit includes: If the operation fault tendency type of the ring main unit is a strong operation fault tendency, it is determined that the operation condition of the ring main unit is unqualified and the reason for the unqualified condition is the presence of a poor contact terminal, and the contact pressure is adjusted based on the slope of the curve, and whether the contact pressure should be corrected is analyzed based on the proportion of the number of abnormal terminals; If the operation fault tendency type of the ring main unit is a weak operation fault tendency, the operation condition of the ring main unit is determined to be qualified.

4. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 3 is characterized in that: The adjusting the contact pressure based on the slope of the curve comprises: The difference between the absolute value of the slope of the curve and the preset absolute value is calculated to obtain the absolute difference, wherein the increase in the contact pressure is positively correlated with the absolute difference.

5. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 4, characterized in that: When the contact pressure is adjusted, analyzing whether to correct the contact pressure based on the proportion of abnormal terminals includes: Filter abnormal terminals and count the number of abnormal terminals. Calculate the ratio of the number of abnormal terminals to the total number of terminals to obtain the abnormal proportion. If the abnormality ratio is greater than or equal to the preset abnormality ratio, it is determined that the contact pressure is not to be corrected; If the abnormality ratio is less than the preset abnormality ratio, it is determined that the contact pressure is to be corrected, wherein the reduction amount of the contact pressure during the correction process is negatively correlated with the abnormality ratio.

6. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 5, characterized in that: When the adjustment of the contact pressure is completed, the current difference between the preset current and the actual current at each terminal is calculated, and the contact pressure for a single terminal is corrected based on the current difference, wherein the increase in contact pressure is positively correlated with the current difference.

7. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 5, characterized in that: When the adjustment of the contact pressure is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring main unit is unqualified, the contact pressure is repeatedly adjusted based on the re-acquired slope of the curve, and it is determined that the reason for the unqualified operating condition of the ring main unit is that the terminal surface is unqualified.

8. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 7, characterized in that: When the terminal surface is judged to be unqualified, the curve data in the current detection cycle is extracted, the curve integral value is calculated, and the processing method is determined based on the curve integral value, including: If the curve integral is less than or equal to the preset curve integral, it is determined that a connector replacement notification signal is issued; If the curve integral is greater than the preset curve integral, it is determined to adjust the heat dissipation operating power.

9. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 8, characterized in that: When determining to adjust the heat dissipation operating power, the integral difference between the curve integral and the preset curve integral is calculated, wherein the increase in the heat dissipation operating power is positively correlated with the integral difference.

10. The intelligent monitoring method for contact resistance fault of a ring main unit according to claim 9, characterized in that: When the adjustment for the heat dissipation operating power is completed, steps S1-S3 are repeated. If it is determined that the operating condition of the ring main unit is unqualified, a connector replacement notification signal is issued.

Images