Low-voltage switch pressure loss intelligent reclosing control system and method

Abstract

The present application relates to the technical field of power system automation control, in particular to a low-voltage switch pressure loss intelligent reclosing control system and method, which collects electrical transient, switch state, topology environment and historical success rate data, respectively calculates fault transient index and reclosing safety index, and compares them with dynamic threshold value to intelligently decide whether to reclose; according to the fault transient index, the first reclosing waiting time is dynamically calculated, the closing is executed and the result is judged by using the post-acceleration protection, if the first reclosing fails, the new data is fused to reevaluate the index, the dynamic delay reclosing attempt is performed for a limited number of times, and finally the closed-loop report is generated, which realizes the upgrade of the reclosing strategy from the traditional "fixed-time trial closing" to "intelligent self-healing", significantly improves the identification and rapid recovery ability for transient faults, effectively prevents the invalid reclosing operation for permanent faults, and enhances the power supply reliability and operation safety of the power line using the system.

Description

Technical Field

[0001] This invention relates to the field of power system automation control technology, specifically to a low-voltage switch undervoltage intelligent reclosing control system and method. Background Technology

[0002] Traditional low-voltage switch reclosing often uses fixed delay logic, which makes it difficult to effectively distinguish between transient and permanent faults. This poses a risk of blind reclosing leading to equipment damage and fault expansion. With the increasing demands for power supply continuity from various power users and the rapid development of intelligent sensing and communication technologies, the realization of adaptive intelligent reclosing technology based on multi-source information fusion has become an important development trend for improving the self-healing capability of low-voltage power supply systems.

[0003] Existing or traditional intelligent reclosing control systems and methods for low-voltage switchgear undervoltage have at least the following technical problems:

[0004] 1. Existing intelligent reclosing control systems and methods for low-voltage switchgear undervoltage lack the ability to perform deep feature fusion and quantitative modeling of multi-source heterogeneous data. They mostly rely on single electrical quantity criteria or simple time series logic, and do not systematically collect and analyze electrical transient waveform details, real-time topology connections and synchronization status, mechanical safety interlocking signals of the switch body, and historical success rate data formed over long-term operation. Due to the lack of comprehensive processing of this information and the formation of composite evaluation indicators such as fault transientity index, the system's judgment of fault nature remains superficial and cannot accurately distinguish between transient and permanent faults.

[0005] 2. Traditional intelligent reclosing control systems and methods for low-voltage switchgear lack dynamic threshold optimization functions based on historical case statistics and self-learning mechanisms. Their decision thresholds are mostly fixed values ​​set based on initial experience. They do not have the ability to collect historical cases of similar equipment and their own operating cases, and therefore cannot be dynamically adjusted as equipment ages, network structure changes, operating environment changes, and fault characteristic distribution changes, resulting in a disconnect between threshold settings and actual risk conditions.

[0006] 3. Existing intelligent reclosing control systems and methods for low-voltage switchgear undervoltage significantly lack adaptive delay calculation logic that is correlated with real-time fault probability assessment results. Their reclosing waiting time is usually a preset fixed value or a simple stepped delay. Their delay strategy is not linked to the instantaneous probability assessment results of the current fault by a mathematical model. They lack a mechanism to dynamically adjust the first and subsequent reclosing waiting times based on the real-time assessment of fault probability. This results in slow recovery when facing high-probability instantaneous faults, affecting power supply continuity indicators. When facing potentially permanent faults, ineffective reclosing may occur due to improper waiting time settings, causing unnecessary secondary current surges to lines and equipment, accelerating equipment deterioration, or even triggering an escalation of the accident. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, this invention provides a low-voltage switch undervoltage intelligent reclosing control system and method, which can effectively solve the problems of fixed-delay blind reclosing and insufficient safety in the prior art.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: The present invention provides a low-voltage switch undervoltage intelligent reclosing control system, comprising:

[0009] The data acquisition and index calculation module is used to collect electrical transient data, switch status data, topology environment data and historical success rate data when the low-voltage switch management line under monitoring loses voltage, and to calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring.

[0010] The intelligent reclosing module based on dual thresholds is used to obtain the fault transient index threshold and the reclosing safety index threshold to assess whether the low-voltage switch under monitoring should be closed.

[0011] The initial closing evaluation module is used to calculate the initial closing waiting time of the low-voltage switch under monitoring when the low-voltage switch under monitoring closes, and to evaluate whether the initial closing of the low-voltage switch under monitoring is successful.

[0012] The reclosing evaluation module is used to perform dynamic reclosing evaluation and output a closing report of the low-voltage switch under monitoring when the first closing of the low-voltage switch fails.

[0013] Preferably, the specific process for calculating the fault transient index corresponding to the low-voltage switchgear management line to be monitored is as follows:

[0014] Based on the current and voltage waveforms in the electrical transient data, calculate the current decay factor and voltage recovery factor of the low-voltage switchgear under monitoring.

[0015] By combining the current attenuation factor and voltage recovery factor of the low-voltage switchgear management line to be monitored, as well as the historical success rate, the fault transient index corresponding to the low-voltage switchgear management line to be monitored is calculated.

[0016] Preferably, the calculation of the reclosing safety index corresponding to the low-voltage switch management line to be monitored is carried out in the following specific process:

[0017] Based on the position status of the low-voltage switch body to be monitored and the operation interlocking command in the switch status data, obtain the position safety factor corresponding to the low-voltage switch to be monitored.

[0018] Based on the voltage status of the load side of the low-voltage switch management line to be monitored in the topology environment data, the voltage amplitude difference and voltage phase difference on both sides of the low-voltage switch to be monitored are obtained. Combined with the maximum amplitude difference and maximum phase difference corresponding to the low-voltage switch to be monitored, the voltage coordination factor corresponding to the low-voltage switch to be monitored is calculated.

[0019] Based on the external environment early warning information in the topology environment data, analyze the external environment factors corresponding to the low-voltage switch to be monitored.

[0020] By combining the location safety factor, voltage coordination factor, and external environmental factor of the low-voltage switch to be monitored, the fault transient index of the low-voltage switch management line to be monitored is calculated.

[0021] Preferably, the specific process for obtaining the fault transientity index threshold and the overlap safety index threshold is as follows:

[0022] Obtain the corresponding low-voltage switch and historical undervoltage event cases for the low-voltage switch to be monitored. Calculate the comparative fault transient index and comparative overlap safety index for the corresponding low-voltage switch in the historical undervoltage cases, and mark the type of each undervoltage event case in the historical undervoltage event cases.

[0023] Based on each undervoltage event case and its corresponding type, the instantaneous index of the initial comparative fault corresponding to each comparative low-voltage switch is analyzed.

[0024] Based on the principle of safety first, an initial comparison overlap safety index is set.

[0025] When the low-voltage switch under monitoring is running, the complete undervoltage reclosing process of the low-voltage switch under monitoring is recorded as a special case. When the number of special cases accumulated exceeds the set number of standard cases, the thresholds of the initial comparison fault transient index and the initial comparison reclosing safety index are optimized, and the optimized initial comparison fault transient index and the initial comparison reclosing safety index are used as the fault transient index threshold and reclosing safety index threshold for subsequent use.

[0026] Preferably, the process of assessing whether the low-voltage switch to be monitored has been closed is as follows:

[0027] By combining the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring, as well as the fault transient index threshold and reclosing safety index threshold, it is assessed whether the low-voltage switch under monitoring should be closed.

[0028] Preferably, the specific process for calculating the initial closing waiting time of the low-voltage switch to be monitored is as follows:

[0029] Based on the fault transient index corresponding to the low-voltage switch to be monitored, and combined with the preset basic waiting time and allowable delay time, the initial closing waiting time of the low-voltage switch to be monitored is calculated.

[0030] Preferably, the process for assessing whether the initial closing of the low-voltage switch under monitoring is successful is as follows:

[0031] After the initial closing operation is performed, the line current passing through the low-voltage switch to be monitored is monitored in real time during the preset closing monitoring window period.

[0032] Based on the real-time monitored line current and the preset protection current setting value, assess whether the first closing of the low-voltage switch under monitoring is successful.

[0033] Preferably, the dynamic reclosing evaluation process is as follows:

[0034] If the initial closing of the low-voltage switch to be monitored fails, a second closing operation will be performed based on the set maximum number of permissible reclosing attempts.

[0035] Reassess whether the monitored low-voltage switch has performed a secondary closing. If it is determined that the monitored low-voltage switch has performed a secondary closing, calculate the secondary waiting time corresponding to the monitored low-voltage switch during the secondary closing and assess whether the secondary closing was successful.

[0036] The reclosing evaluation will stop when the number of reclosing attempts exceeds the maximum allowable number of reclosing attempts or when the low-voltage switch to be monitored is successfully closed.

[0037] Preferably, the specific process for outputting the closing report of the low-voltage switch to be monitored is as follows:

[0038] When the number of reclosing attempts is greater than the maximum allowable number of reclosing attempts, or when the number of reclosing attempts is less than the maximum allowable number of reclosing attempts, a closing report of the low-voltage switch to be monitored is generated and output.

[0039] In a second aspect, the present invention provides a low-voltage switch undervoltage intelligent reclosing control method, comprising:

[0040] S1. When the low-voltage switch management line under monitoring loses voltage, collect electrical transient data, switch status data, topology environment data and historical success rate data, and calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring.

[0041] S2. Obtain the fault transient index threshold and the reclosing safety index threshold, and then assess whether the low-voltage switch under monitoring should be closed.

[0042] S3. When the low-voltage switch under monitoring closes, calculate the waiting time for the first closing of the low-voltage switch under monitoring, and evaluate whether the first closing of the low-voltage switch under monitoring is successful.

[0043] S4. When the first closing of the low-voltage switch under monitoring fails, perform dynamic reclosing evaluation and output the closing report of the low-voltage switch under monitoring.

[0044] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0045] 1. In the data acquisition and multi-dimensional index calculation process of this invention, the system synchronously collects electrical transient data, switch status data, topology environment data and historical success rate data, and constructs a quantitative evaluation model of fault transientness index and overlap safety index. This helps to transform the originally isolated field information into unified and comparable numerical indicators, and helps to more scientifically quantify the probability that the fault is transient and comprehensively evaluate the safety level of this closing operation. This provides an accurate and reliable data foundation for subsequent intelligent decision-making, and changes the previous rough judgment mode that relied on a single or a few criteria.

[0046] 2. In the intelligent re-closing decision-making process based on dual thresholds, the system acquires and applies dynamically optimized fault transientity index thresholds and re-closing safety index thresholds for evaluation, which helps to achieve a precise balance between safety and efficiency. By statistically analyzing historical cases and following the principle of safety priority for initial setting and continuous optimization, the system's judgment criteria have self-learning and adaptive capabilities, which helps to continuously approach the risk characteristics of the actual power grid as operating experience accumulates, thereby maintaining the scientific and optimal nature of decision-making in long-term operation.

[0047] 3. In the dynamic calculation of the first closing waiting time in the embodiment of the present invention, the system combines the calculated fault transient index with the preset basic waiting time and allowable delay time, and uses a formula to dynamically generate the first reclosing waiting time. This is conducive to realizing the personalization and optimization of recovery timeliness, overcoming the drawback of the fixed delay "one-size-fits-all", and maximizing the recovery speed of transient faults while ensuring safety.

[0048] 4. In the closed-loop dynamic re-evaluation and retry process of this invention, after the first closing failure, the system does not simply repeat the original operation, but instead re-collects data, recalculates the evaluation index, and introduces a penalty delay mechanism and count weight to dynamically decide whether and when to make the next re-closing attempt. This is beneficial for dealing with complex fault scenarios and improving the success rate of the final recovery, forming an intelligent closed loop of "evaluation-execution-feedback-re-evaluation". This limited number of retry strategies with intelligent adjustment significantly improves the recovery capability for "stubborn" transient faults that are between instantaneous and permanent or subject to changing conditions. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0050] Figure 1 This is a schematic diagram of the system structure connection of the present invention.

[0051] Figure 2 This is a schematic diagram of the implementation steps of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] The present invention will be further described below with reference to embodiments.

[0054] Please see Figure 1 As shown, a low-voltage switchgear undervoltage intelligent reclosing control system includes at least:

[0055] The data acquisition and index calculation module is used to collect electrical transient data, switch status data, topology environment data and historical success rate data when the low-voltage switch management line under monitoring loses voltage, and to calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring.

[0056] In a specific embodiment, the process of collecting electrical transient data, switch status data, topology environment data, and historical success rate data is as follows: electrical transient data includes voltage waveforms and current waveforms; switch status data includes the switch body position status and operation interlocking commands; and topology environment data includes the voltage status on the line load side and external environment early warning information.

[0057] The corresponding current and voltage waveforms are obtained by connecting voltage and current transformers to the low-voltage switch management line to be monitored.

[0058] The position status and operation lockout commands of the low-voltage switch under test are obtained through the auxiliary contacts of the low-voltage switch under test and the controller commands.

[0059] The local communication module obtains the corresponding voltage status from the end node of the line, and obtains external environmental warning information from the external early warning system.

[0060] Query the historical success rate directly from the database.

[0061] It should be noted that the historical success rate mentioned in the pre-statistics was obtained before the current power outage event by counting the total number of closing operations and the number of successful reclosing operations during the power outage, and then dividing the number of successful reclosing operations by the total number of closing operations.

[0062] It should be noted that the voltage waveform in the electrical transient data is a high-sampling-rate instantaneous value sequence at the moment of the fault, measured in milliseconds. For example, a lightning strike causes the voltage to drop sharply to zero within 1-2 cycles, accompanied by high-frequency oscillations. This waveform records the dynamic drop process and is used to calculate the voltage recovery factor. The line load-side voltage status in the topology environment data is the effective voltage value at the second level after the fault, or a Boolean state indicating whether the line is energized or not. For example, if the voltage at the end of the line is 0kV after a fault, it indicates that the fault point is located between the switch and the end (complete line loss of voltage). If the voltage at the end is normal (e.g., 0.4kV), it indicates that only the front end of the switch is de-energized. This status is used to determine the fault range and the power recovery status, and is used to calculate the synchronization factor.

[0063] It should be noted that auxiliary contacts are miniature switches installed on the switch operating mechanism. Their on / off state is mechanically linked to the physical position (closed / open) of the main switch contacts, providing an electrical signal indicating the actual position of the switch. "Controller commands" refer to control signals issued by an intelligent control unit (such as a PLC or protection device) based on logical judgment, such as remote opening / closing commands or interlocking signals triggered by other protection conditions.

[0064] The physical position status refers to the real-time physical position of the switch, such as "closed", "open" or "test / isolate" position; the operation interlock command is a highest priority prohibition signal, which may come from the mechanical padlock (electrical contact) during maintenance, the linkage output of other protection devices, or the manual interlock command of the operation and maintenance personnel.

[0065] In a specific embodiment, the calculation of the fault transient index corresponding to the low-voltage switchgear management line to be monitored is carried out as follows: based on the current waveform and voltage waveform in the electrical transient data, the current decay factor and voltage recovery factor of the low-voltage switchgear management line to be monitored are calculated.

[0066] The current attenuation factor of the low-voltage switch management circuit to be monitored The calculation formula is: ,in It is expressed as the time constant required for the fault current to decay from its peak value to a preset proportion. This is the preset reference time constant.

[0067] The voltage recovery factor of the low-voltage switch management circuit to be monitored The calculation formula is: , This represents the average rate of change of voltage within a preset time window after voltage loss. This is represented as a preset voltage change rate reference value, used for normalization. is the hyperbolic tangent function, used to map the result to the interval [0,1).

[0068] Combining the current attenuation factor and voltage recovery factor of the low-voltage switchgear under monitoring, as well as the historical success rate, the following calculation formula is used: The fault transient index corresponding to the low-voltage switch management line to be monitored is obtained. ,in This is expressed as the historical success rate. This represents the weighting coefficient corresponding to the set historical success rate.

[0069] It should be noted that, It is the natural exponential function, which is an exponential operation with the natural constant e (approximately 2.718) as the base.

[0070] It should be noted that, The acquisition process involves directly analyzing the current waveform acquired in step S1. Specifically, the peak point of the fault current is identified in the waveform, and the actual time it takes for the peak value to decay to a preset proportion (the preset proportion is an engineering experience value determined based on statistical analysis of a large number of historical fault current waveforms of the target, such as 10%) is calculated. This time value is used as the decay time constant for this fault. ; These are preset system reference parameters, the values ​​of which are determined based on statistical experience values ​​(e.g., 0.1 seconds) of the decay time of a large number of typical transient fault currents in the target power grid.

[0071] It should be noted that, The average value is obtained by performing differential calculation on voltage waveform data collected within a preset time window (an empirical value set based on the deionization time of the arc after a power system fault and the typical duration of the system transient process, such as 0.1 seconds). The unit is volts per second, which is used to quantify the trend and rate of voltage recovery. Each component of the voltage recovery factor calculation formula (the dimensionless processing of the ratio of the voltage change rate, the hyperbolic tangent function, and the reference value) is common knowledge and mature technology in the fields of electrical engineering and signal processing, so it will not be elaborated on here.

[0072] It should be noted that, The value of is greater than 0 and less than 1. The setup process is based on the expert experience method and historical data simulation method commonly used in multi-factor decision analysis in existing technologies. In this scheme, this method is applied to balance the relative contributions of real-time electrical characteristics and long-term historical statistics in fault nature assessment: First, before conducting the reclosing assessment of the low-voltage switch to be monitored, an initial value is preset based on domain experience (e.g., greater reliance on real-time characteristics). (0.2), and then, during operation, the control system compares... The coefficient is adjusted offline to assess the long-term consistency between the evaluation conclusions and the actual results.

[0073] In a specific embodiment, the reclosing safety index corresponding to the low-voltage switch management line to be monitored is calculated. The specific process is as follows: Based on the switch status data including the body position status and operation interlocking command, the position safety factor corresponding to the low-voltage switch to be monitored is obtained. The position safety factor is 1 or 0. The position safety factor is 1 if and only if the low-voltage switch to be monitored is in the working position and there is no remote interlocking signal. Otherwise, the position safety factor is 0.

[0074] Based on the voltage status of the load side of the low-voltage switch management line to be monitored in the topology environment data, the voltage amplitude difference between the two sides of the low-voltage switch to be monitored is obtained. and voltage phase difference Combined with the maximum amplitude difference corresponding to the low-voltage switch to be monitored and maximum phase difference Through the calculation formula: The voltage coordination factor corresponding to the low-voltage switch to be monitored is obtained. .

[0075] Based on the external environment early warning information in the topology environment data, the external environment factors corresponding to the low-voltage switch to be monitored are obtained.

[0076] Combining the location safety factor, voltage coordination factor, and external environmental factor of the low-voltage switch to be monitored, the calculation formula is as follows: The reclosing safety index corresponding to the low-voltage switch management line to be monitored is obtained, where and These represent the position safety factor and external environmental factor corresponding to the low-voltage switch to be monitored, respectively.

[0077] It should be noted that the process of obtaining the position safety factor corresponding to the low-voltage switch under monitoring is based on the fundamental principles of position reliability and interlock release in power safety operation. The physical position refers to the physical position directly detected by the switch's mechanical auxiliary contacts; for example, the open position represents a working position where closing operations can be performed. The "operation interlock command" refers to an electrical or logical signal from the protection system, local interlock switch, or remote monitoring system prohibiting operation. For example, even if the switch is in the correct open position (working position), if maintenance personnel engage a mechanical interlock (its attached electrical contacts issue an interlock command), it is deemed unsafe (position safety factor is 0), and the control system will be absolutely prohibited from operation. Only when both conditions are met simultaneously—correct physical position and no interlock command—is it deemed safe and operable (position safety factor is 1).

[0078] It should be noted that, and The acquisition process is based on voltage synchronization detection technology in the distribution network. One side of the voltage on both sides of the switch is the voltage at the switch's own installation point (measured by a local voltage transformer), and the other side is the voltage on the line load side (the voltage status information obtained from the load-side node via a communication module includes amplitude and phase data). By comparing these two sets of real-time measurements, the voltage is directly calculated. and ; and It is a preset safety threshold, and its setting process is determined comprehensively based on the allowable closing inrush current of the switching equipment, the system stability regulations, and relevant electrical standards (such as the synchronous closing error allowed in the equipment technical specifications).

[0079] It should be noted that the specific process for monitoring the external environmental factors corresponding to the low-voltage switch is based on the fundamental principle of mapping environmental information with electrical equipment risk in existing technologies. In this solution, this principle is applied to the real-time safety quantitative assessment of reclosing: the system receives external early warning information (such as lightning and strong wind warnings) from meteorological departments in real time, and converts it into a specific value within the range of (0,1] according to preset mapping rules, i.e., the external environmental factor. For example, when an orange lightning warning is received, the system directly maps it to... =0.3, without any warning, then it is mapped to =1, the example is for illustrative purposes only and is not the only limitation.

[0080] In the data acquisition and multi-dimensional index calculation process of this invention, the system synchronously collects electrical transient data, switch status data, topology environment data, and historical success rate data, and constructs a quantitative evaluation model for fault transientity index and overlap safety index. This helps to transform the originally isolated field information into unified and comparable numerical indicators, and helps to more scientifically quantify the probability that the fault is transient and comprehensively evaluate the safety level of this closing operation. This provides an accurate and reliable data foundation for subsequent intelligent decision-making, and changes the previous rough judgment mode that relied on a single or a few criteria.

[0081] The intelligent reclosing module based on dual thresholds is used to obtain the fault transient index threshold and the reclosing safety index threshold based on the fault transient index and the reclosing safety index corresponding to the low-voltage switch under monitoring, and then evaluate whether the low-voltage switch under monitoring should be closed.

[0082] In a specific embodiment, the process of obtaining the fault transientity index threshold and the overlap safety index threshold is as follows: retrieve historical undervoltage event cases corresponding to the same low-voltage switch model and application scenario as the one to be monitored from the database, calculate the comparative fault transientity index and comparative overlap safety index of the corresponding low-voltage switch in the historical undervoltage cases, and mark the type of each undervoltage event case in the historical undervoltage event cases. The undervoltage event case types include transient and permanent.

[0083] Based on each case of pressure loss event and its corresponding type, an initial comparative fault transient index is obtained using statistical analysis methods.

[0084] Based on the principle of safety first, the initial comparison overlap safety index is directly set.

[0085] When the low-voltage switch under monitoring is running, the complete undervoltage reclosing process of the low-voltage switch under monitoring is recorded as a special case. When the number of special cases accumulated exceeds the set number of standard cases, the thresholds of the initial comparison fault transient index and the initial comparison reclosing safety index are optimized, and the optimized initial comparison fault transient index and the initial comparison reclosing safety index are used as the fault transient index threshold and reclosing safety index threshold for subsequent use.

[0086] It should be noted that transient refers to a line abnormality that causes the switch to trip that is temporary (such as the disappearance of lightning overvoltage or a foreign object briefly touching the line and then falling off). After the switch trips and isolates the fault, the line has automatically restored its insulation level. In this case, after performing a reclosing operation, the power supply can be successfully restored and remain stable. Permanent refers to a line abnormality that causes the switch to trip that is persistent (such as a permanent wire break or equipment insulation breakdown). The fault point has not disappeared. In this case, after performing a reclosing operation, the fault current will be detected again immediately, causing the protection to trip (i.e., reclosing fails).

[0087] It should be noted that the process of obtaining the initial comparative fault transientity index using statistical analysis methods is based on statistical classification or machine learning algorithms (such as logistic regression, support vector machine, or finding the optimal discrimination point through ROC curve). In this scheme, its specific application is as follows: the fault transientity index value calculated for each case in the historical case set is used as a feature, and the known fault type (transient / permanent) of the case is used as a label to form a training dataset. Through the selected statistical analysis method, a fault transientity index critical value that can achieve the best differentiation effect between the two types of labels is found. This critical value is set as the initial fault transientity index threshold.

[0088] It should be noted that the process of directly setting the initial comparison and overlap safety index is based on the safety priority principle generally followed in existing engineering practices. In this scheme, the specific application is: without relying on the corresponding historical undervoltage event cases and the undervoltage event cases corresponding to the low-voltage switch to be monitored, a relatively high value (e.g., 0.7) is directly preset as the initial overlap safety index threshold.

[0089] It should be noted that the set standard number of cases is an empirical value preset based on the significance test and model stability requirements in statistics. It is set with reference to the minimum sample size required to obtain stable distribution parameters in statistics (e.g., more than 30 cases to meet the requirements of the central limit theorem for approximate normal distribution) or the training set size required for a specific classification algorithm to achieve stable performance, and in combination with the speed of data accumulation in actual applications.

[0090] It should be noted that the threshold optimization process is as follows: when the number of dedicated cases accumulated by the low-voltage switch to be monitored reaches the standard, the dedicated cases are merged with historical undervoltage event cases to generate a new training dataset. Based on the new training dataset, the initial process of obtaining the fault transient index is re-executed. For example, a new ROC curve is plotted based on the merged training dataset and the optimal discrimination point is found (existing technology) to obtain a new fault transient index threshold. At the same time, records in the training dataset that are blocked due to insufficient overlap safety index are counted. If they exist, the overlap safety index threshold is slightly lowered (not greater than a step size such as 0.05) to obtain a new overlap safety index threshold.

[0091] In a specific embodiment, the process of evaluating whether the low-voltage switch under monitoring should be closed is as follows: the fault transient index and reclosing safety index corresponding to the line managed by the low-voltage switch under monitoring are compared with the corresponding fault transient index threshold and reclosing safety index threshold. If the fault transient index > fault transient index threshold and the reclosing safety index > reclosing safety index threshold are satisfied at the same time, it is determined that the low-voltage switch under monitoring should be closed, and the first closing waiting time of the low-voltage switch under monitoring is calculated. Otherwise, it is determined that the low-voltage switch under monitoring should not be closed.

[0092] In the intelligent re-closing decision-making process based on dual thresholds, the system acquires and applies dynamically optimized fault transientity index thresholds and re-closing safety index thresholds for evaluation, which helps to achieve a precise balance between safety and efficiency. By statistically analyzing historical cases and following the principle of safety priority for initial settings and continuous optimization, the system's judgment criteria have self-learning and adaptive capabilities, which helps to continuously approach the risk characteristics of the actual power grid as operational experience accumulates, thereby maintaining the scientific and optimal nature of decision-making in long-term operation.

[0093] The initial closing evaluation module is used to calculate the initial closing waiting time of the low-voltage switch under monitoring when the low-voltage switch under monitoring closes, and to evaluate whether the initial closing of the low-voltage switch under monitoring is successful.

[0094] In a specific embodiment, the calculation of the initial closing waiting time of the low-voltage switch to be monitored is carried out as follows: based on the fault transient index corresponding to the low-voltage switch to be monitored, combined with a preset basic waiting time... and allowed delay duration Through the calculation formula: The initial closing waiting time of the low-voltage switch to be monitored is obtained. .

[0095] It should be noted that the setting process is based on the shortest safe time that the reclosing operation must meet, determined by the physical characteristics of the equipment and the electrical characteristics of the system. It is obtained by adding up the reliable extinction time of the fault arc, the inherent time of the switch operating mechanism, and the system electrical transient decay time. The reliable extinction time of the fault arc is the time required for the fault arc to ionize and restore insulation after the line fault trips (e.g., 0.1-0.2 seconds). The inherent time of the switch operating mechanism is the mechanical action time required for the switch to reliably close its contacts from receiving the closing command (e.g., 0.05-0.1 seconds). The system electrical transient decay time is the time required for transient phenomena such as operating overvoltage and inrush current caused by the instant the switch closes to basically subside (e.g., 0.05-0.1 seconds).

[0096] It should be noted that, The setup process is as follows: By analyzing historical operating data of the target application scenario (such as a specific regional power distribution network), the typical time required from occurrence to clear identification or isolation in a large number of permanent or complex fault cases is determined statistically, and its statistical upper limit (such as the 95th percentile) is used as a reference; for example, if the analysis shows that 95% of such events can be effectively handled within 0 seconds, then... Set to 10 seconds.

[0097] In a specific embodiment, the process of evaluating whether the first closing of the low-voltage switch to be monitored is successful is as follows: after the first closing operation is performed, the control system starts a closing monitoring window of a preset duration, and during the closing monitoring window period, the line current passing through the low-voltage switch to be monitored is monitored in real time.

[0098] If the line current monitored in real time does not exceed the preset protection current setting value, the first closing is considered successful.

[0099] If the line current monitored in real time exceeds the preset protection current setting value at any time, the first closing failure is determined, and the low-voltage switch to be monitored is opened.

[0100] It should be noted that the preset closing monitoring window is determined based on statistics and actual measurements of the inherent operating time of the post-acceleration protection relay, the transmission time of the current transformer, and the processing and output delay of the controller. Taking a low-voltage power distribution system as an example, the typical empirical value of this closing monitoring window is often set to 80 milliseconds to 150 milliseconds.

[0101] It should be noted that the preset protection current setting value is based on the basic principles and methods of relay protection setting calculation in the existing technology (i.e., "reliably avoid the maximum load current and reliably operate at the minimum short-circuit current"). In this scheme, it is directly used as the execution threshold of the post-acceleration protection logic, so the specific setting process will not be described in detail.

[0102] In the dynamic calculation of the first closing waiting time in this embodiment of the invention, the system combines the calculated fault transient index with the preset basic waiting time and allowable delay time, and uses a formula to dynamically generate the first reclosing waiting time. This is beneficial to achieve personalized and optimized recovery timeliness, overcomes the drawbacks of fixed delay "one-size-fits-all", and maximizes the recovery speed of transient faults while ensuring safety.

[0103] The reclosing evaluation module is used to perform dynamic reclosing evaluation when the first closing of the low-voltage switch under monitoring fails, and outputs a closing report of the low-voltage switch under monitoring based on the final closing result of the low-voltage switch under monitoring.

[0104] In a specific embodiment, the dynamic reclosing evaluation process is as follows: When it is determined that the first closing of the low-voltage switch to be monitored is unsuccessful, a second closing is performed based on the set maximum allowable number of reclosing attempts, and the number of reclosing attempts is recorded as follows. The first closing corresponds to The value is 1.

[0105] Based on the evaluation process of steps S1 and S2, the re-evaluation is performed to determine whether the monitored low-voltage switch has undergone secondary closing. If it is determined that the monitored low-voltage switch has undergone secondary closing, the reclosing calculation formula is used: The secondary waiting time corresponding to the low-voltage switch to be monitored during the secondary closing is obtained. , This is the penalty delay duration for reclosing. To adjust the weighting coefficient of the fault transientity index on the delay effect, This indicates the fault transient index of the low-voltage switchgear under monitoring during secondary closing;

[0106] Based on the secondary waiting time corresponding to the low-voltage switch to be monitored during the secondary closing, the secondary closing of the low-voltage switch to be monitored is performed, and the success of the secondary closing is evaluated.

[0107] If the secondary closing is successful, the closing report of the low-voltage switch to be monitored will be output directly.

[0108] If the second reclosing attempt fails, a third reclosing attempt will be made until the number of reclosing attempts exceeds the maximum allowable number of reclosing attempts or the low-voltage switch under monitoring successfully closes, at which point the reclosing process will stop.

[0109] It should be noted that the setting process for the maximum allowable number of reclosing operations is based on the mechanical and electrical life of the low-voltage switch body under monitoring and the number of repeated impacts allowed by the system. Specifically, according to the technical standards and type test reports of this type of switch, the typical number of cycles (e.g., 3 or 4) that it can reliably complete the "open-close-open" operation continuously under the specified short-circuit current is determined. This is taken as the theoretical upper limit. Combined with the operation and maintenance strategy of the specific application scenario (e.g., reducing attempts to reduce risks in unattended sites), a conservative value (e.g., 2 times) is selected within this upper limit range as the value of the maximum allowable number of reclosing operations.

[0110] It should be noted that, The setting process is based on the operating experience and safety guidelines of the circuit managed by the low-voltage switch under monitoring or similar circuits; for example, if the maintenance response time of the circuit managed by the low-voltage switch under monitoring is approximately 15 minutes, to avoid invalid overlap and leave a safety window, 1 / 10 (i.e., 90 seconds) of it can be set as [value missing]. This indicates that each subsequent attempt will wait an additional 90 seconds compared to the previous one.

[0111] It should be noted that, Used to balance the fault transient index with a fixed number of penalties during each reclosing. Its relative influence in the total delay calculation; its value is based on expert experience and preset. If the control system is required to "trust" the fault transient index obtained from each reassessment more, then it is assigned... Larger values ​​(e.g.) =2), making the delay more sensitive to changes in the transient nature of the fault; if the cumulative effect of the number of attempts penalty is emphasized to suppress blind retries, then... Smaller values ​​(e.g.) =0.5)

[0112] In a specific embodiment, the process of outputting the closing report of the low-voltage switch to be monitored is as follows: when the closing is successful, the closing report of the low-voltage switch to be monitored is generated and output.

[0113] It should be noted that the closing report includes, but is not limited to, the fault transient index and reclosing safety index calculated from each assessment and their corresponding thresholds, the decision result of each reclosing operation, the waiting time, and the monitoring results (success or failure) after each closing operation.

[0114] Please see Figure 2 As shown, a low-voltage switch undervoltage intelligent reclosing control method includes the following steps:

[0115] S1. When the low-voltage switch management line under monitoring loses voltage, collect electrical transient data, switch status data, topology environment data and historical success rate data, and calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring.

[0116] S2. Based on the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring, obtain the fault transient index threshold and the reclosing safety index threshold, and then evaluate whether the low-voltage switch under monitoring should be closed.

[0117] S3. When the low-voltage switch under monitoring closes, calculate the waiting time for the first closing of the low-voltage switch under monitoring, and evaluate whether the first closing of the low-voltage switch under monitoring is successful.

[0118] S4. If the first closing of the low-voltage switch to be monitored fails, a dynamic reclosing evaluation is performed, and a closing report of the low-voltage switch to be monitored is output based on the final closing result of the low-voltage switch to be monitored.

[0119] In the closed-loop dynamic re-evaluation and retry process of this invention, after the first closing failure, the system does not simply repeat the original operation. Instead, it re-collects data, recalculates the evaluation index, and introduces a penalty delay mechanism and count weight to dynamically decide whether and when to make the next re-closing attempt. This is beneficial for dealing with complex fault scenarios and improving the success rate of the final recovery, forming an intelligent closed loop of "evaluation-execution-feedback-re-evaluation". This limited-number, intelligently adjusted retry strategy significantly improves the recovery capability for "stubborn" transient faults that are between instantaneous and permanent or subject to changing conditions.

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-voltage switch undervoltage intelligent reclosing control system, characterized in that, include: The data acquisition and index calculation module is used to collect electrical transient data, switch status data, topology environment data and historical success rate data when the low-voltage switch management line under monitoring loses voltage, and calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring, respectively. The specific process for calculating the reclosing safety index of the low-voltage switchgear management line to be monitored is as follows: Based on the position status of the low-voltage switch body to be monitored and the operation interlocking command in the switch status data, obtain the position safety factor corresponding to the low-voltage switch to be monitored. Based on the voltage status of the load side of the low-voltage switch management line to be monitored in the topology environment data, the voltage amplitude difference and voltage phase difference on both sides of the low-voltage switch to be monitored are obtained. Combined with the maximum amplitude difference and maximum phase difference corresponding to the low-voltage switch to be monitored, the voltage coordination factor corresponding to the low-voltage switch to be monitored is calculated. Based on the external environment early warning information in the topology environment data, analyze the external environment factors corresponding to the low-voltage switch to be monitored; By combining the location safety factor, voltage coordination factor and external environmental factor of the low-voltage switch to be monitored, the overclosing safety index of the management line of the low-voltage switch to be monitored is calculated. The intelligent reclosing module based on dual thresholds is used to obtain the fault transient index threshold and the reclosing safety index threshold to assess whether the low-voltage switch under monitoring should be closed. The initial closing evaluation module is used to calculate the initial closing waiting time of the low-voltage switch under monitoring when the low-voltage switch under monitoring closes, and to evaluate whether the initial closing of the low-voltage switch under monitoring is successful. The reclosing evaluation module is used to perform dynamic reclosing evaluation and output a closing report of the low-voltage switch under monitoring when the first closing of the low-voltage switch fails.

2. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 1, characterized in that, The specific process for calculating the fault transient index corresponding to the low-voltage switchgear management line to be monitored is as follows: Based on the current and voltage waveforms in the electrical transient data, calculate the current decay factor and voltage recovery factor of the low-voltage switchgear management line to be monitored. By combining the current attenuation factor and voltage recovery factor of the low-voltage switchgear management line to be monitored, as well as the historical success rate, the fault transient index corresponding to the low-voltage switchgear management line to be monitored is calculated.

3. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 1, characterized in that, The specific process for obtaining the fault transientity index threshold and the overlap safety index threshold is as follows: Obtain the corresponding low-voltage switch to be monitored and the corresponding historical undervoltage event cases. Calculate the comparative fault transient index and comparative overlap safety index of the corresponding low-voltage switch in the historical undervoltage cases, and mark the type of each undervoltage event case in the historical undervoltage event cases. Based on each undervoltage event case and its corresponding type, the instantaneous index of the initial comparative fault for each comparative low-voltage switch is analyzed. Based on the principle of safety first, an initial comparison overlap safety index is set; When the low-voltage switch under monitoring is running, the complete undervoltage reclosing process of the low-voltage switch under monitoring is recorded as a special case. When the number of special cases accumulated exceeds the set number of standard cases, the thresholds of the initial comparison fault transient index and the initial comparison reclosing safety index are optimized, and the optimized initial comparison fault transient index and the initial comparison reclosing safety index are used as the fault transient index threshold and reclosing safety index threshold for subsequent use.

4. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 3, characterized in that, The specific process for assessing whether the low-voltage switch under monitoring has been closed is as follows: By combining the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring, as well as the fault transient index threshold and reclosing safety index threshold, it is assessed whether the low-voltage switch under monitoring should be closed.

5. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 4, characterized in that, The specific process for calculating the initial closing waiting time of the low-voltage switch to be monitored is as follows: Based on the fault transient index corresponding to the low-voltage switch to be monitored, and combined with the preset basic waiting time and allowable delay time, the initial closing waiting time of the low-voltage switch to be monitored is calculated.

6. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 5, characterized in that, The specific process for assessing whether the initial closing of the low-voltage switch under monitoring was successful is as follows: After the first closing operation is performed, the line current passing through the low-voltage switch to be monitored is monitored in real time during the preset closing monitoring window period. Based on the real-time monitored line current and the preset protection current setting value, assess whether the first closing of the low-voltage switch under monitoring is successful.

7. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 6, characterized in that, The specific process for performing dynamic reclosing evaluation is as follows: If the initial closing of the low-voltage switch to be monitored fails, a second closing operation is performed based on the set maximum allowable number of reclosing attempts. Reassess whether the monitored low-voltage switch has performed a secondary closing. If it is determined that the monitored low-voltage switch has performed a secondary closing, calculate the secondary waiting time corresponding to the monitored low-voltage switch during the secondary closing and assess whether the secondary closing was successful. The reclosing evaluation will stop when the number of reclosing attempts exceeds the maximum allowable number of reclosing attempts or when the low-voltage switch to be monitored is successfully closed.

8. The intelligent reclosing control system for low-voltage switch undervoltage as described in claim 7, characterized in that, The specific process for outputting the closing report of the low-voltage switch to be monitored is as follows: When the number of reclosing attempts is greater than the maximum allowable number of reclosing attempts, or when the number of reclosing attempts is less than the maximum allowable number of reclosing attempts, a closing report of the low-voltage switch to be monitored is generated and output.

9. A low-voltage switch undervoltage intelligent reclosing control method for implementing the low-voltage switch undervoltage intelligent reclosing control system according to any one of claims 1-8, characterized in that, The steps include the following: S1. When the low-voltage switch management line under monitoring loses voltage, collect electrical transient data, switch status data, topology environment data and historical success rate data, and calculate the fault transient index and reclosing safety index corresponding to the low-voltage switch management line under monitoring respectively. S2. Obtain the fault transient index threshold and the reclosing safety index threshold, and then assess whether the low-voltage switch under monitoring should be closed. S3. When the low-voltage switch under monitoring closes, calculate the waiting time for the first closing of the low-voltage switch under monitoring, and evaluate whether the first closing of the low-voltage switch under monitoring is successful. S4. When the first closing of the low-voltage switch under monitoring fails, perform dynamic reclosing evaluation and output the closing report of the low-voltage switch under monitoring.

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