A power distribution network ground fault auxiliary pull line research and judgment method and system

Abstract

The application discloses a power distribution network grounding fault auxiliary pull line judgment method and system, relates to the power system distribution network automation technical field, and comprises the following steps: collecting the zero sequence voltage of a transformer substation bus and the zero sequence current of each outgoing line in real time, and preprocessing; monitoring the zero sequence voltage of each transformer substation bus, when the zero sequence voltage of the bus exceeds the differentiated threshold, and lasts for a preset time length, then it is determined that a grounding fault occurs, and a pop-up window alarm is triggered; calculating the mutation quantity of the zero sequence voltage of the bus at the grounding fault triggering moment, and the mutation quantity of the zero sequence current of each outgoing line; using a preset mutation quantity algorithm, calculating the comprehensive coefficient of each outgoing line, and sorting the comprehensive coefficients of the outgoing lines to obtain a fault line candidate sorting list; according to the fault line candidate sorting list, using an automatic or semi-automatic mode, performing a pull line on the outgoing line, and cutting off the fault line. The application can greatly reduce the decision difficulty.

Description

Technical Field

[0001] This invention belongs to the field of power system distribution network automation technology, specifically relating to an auxiliary circuit analysis method and system for grounding faults in distribution networks. Background Technology

[0002] Distribution networks are characterized by long lines, numerous branches, and complex operating environments. Especially in mountainous areas of southern China, lines often pass through densely populated areas or mountainous forests, making them prone to electric shock accidents and wildfires caused by electrical equipment failures. When a single-phase ground fault occurs in a distribution network, the fault current is relatively small, especially in high-resistance grounding where the transition resistance can reach several kΩ. Traditional low-current fault location devices often fail to operate effectively due to insufficient sensitivity of the starting value.

[0003] Currently, most power supply companies have deployed distribution automation systems, enabling remote measurement, signaling, and control of 10kV lines. Substations are generally equipped with low-current fault location devices, but their accuracy in locating high-resistance grounding faults is low. When a grounding fault occurs, dispatchers still primarily rely on manual experience to troubleshoot by pulling lines one by one, based on the bus zero-sequence voltage (U0) exceeding the limit alarm, combined with changes in the zero-sequence current (I0) of each outgoing line, until the grounding signal disappears. Some research has explored using transient or steady-state quantities for fault location, but these methods suffer from complex algorithms and poor field adaptability.

[0004] Therefore, there is an urgent need to provide an auxiliary method and system for judging grounding faults in power distribution networks in order to improve the problems existing in the current technology. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides an auxiliary circuit-based analysis method and system for grounding faults in power distribution networks. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides an auxiliary circuit analysis method for grounding faults in a distribution network, comprising: The zero-sequence voltage of the substation busbar and the zero-sequence current of each outgoing line are collected in real time and preprocessed. Monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset time, a ground fault is determined to have occurred, triggering a pop-up alarm. Calculate the sudden change in zero-sequence voltage of the bus and the sudden change in zero-sequence current of each outgoing line at the moment of ground fault triggering; use a preset sudden change algorithm to calculate the comprehensive coefficient of each outgoing line, and sort the comprehensive coefficients of each outgoing line to obtain a candidate list of fault lines. Based on the candidate faulty line sorting list, the outgoing lines are disconnected automatically or semi-automatically to isolate the faulty lines.

[0006] Optionally, the zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are collected in real time and preprocessed, including: The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are collected at a preset sampling frequency. The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are filtered and denoised.

[0007] Optionally, a preset mutation rate algorithm is used to calculate the comprehensive coefficient of each outgoing line, and the comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines, including: Record the trigger time of the ground fault And extract the first preset time window before the ground fault is triggered and the second preset time window after the ground fault is triggered; For each outgoing line, the zero-sequence current abrupt change is calculated based on the average zero-sequence current of the first preset time window and the average zero-sequence current of the second preset time window. Calculate the normalized current change of each outgoing line based on the zero-sequence current change of each outgoing line; calculate the phase characteristic coefficient of each outgoing line based on the phase difference between the zero-sequence current of each outgoing line and the zero-sequence voltage of the bus before and after the ground fault is triggered. Calculate the comprehensive coefficient of each outgoing line based on the normalized current abrupt change and phase characteristic coefficient of each outgoing line; The comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines.

[0008] Optionally, the normalized current abrupt change of each outgoing line is expressed as: ; in, Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The sudden change in zero-sequence current of the outgoing line. Indicates the first The sudden change in zero-sequence current of the outgoing line. This indicates the total number of teams that qualified.

[0009] Optionally, the composite coefficient for each qualifying line is expressed as follows: ; in, Indicates the first The overall coefficient of each line is... Indicates the first Weighting coefficients for normalized current abrupt changes in outgoing lines. Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The weighting coefficient of the phase characteristic coefficient of the outgoing line. Indicates the first Phase characteristic coefficient of the output line.

[0010] Optionally, the process of obtaining the differentiation threshold includes: Based on the magnitude of the substation's capacitive current, the initial differentiation threshold is calculated using an empirical formula, expressed as: ; in, Indicates the initial differentiation threshold. Indicates the rated phase voltage of the busbar; Collect data on zero-sequence voltage exceeding the limit events of all busbars within a preset time period, mark manually confirmed non-grounding fault events, and calculate the maximum zero-sequence voltage value of the busbar corresponding to the exceeding event. Update the initial differentiation threshold to: ; in, Indicates the difference threshold. Indicates the initial threshold. This represents the maximum value of the zero-sequence voltage of the bus.

[0011] The differentiation threshold is dynamically adjusted by periodic updates.

[0012] Optionally, it also includes: A verification rule base is constructed to record the trigger time of grounding faults, the waveform of zero-sequence current of each outgoing line, the candidate ranking list of faulty lines, the actual disconnection line, and the change of zero-sequence voltage of the bus after disconnection. The rules in the verification rule base include rules to prevent maloperation, rules to prevent refusal to operate, remote control permission verification, and communication status verification.

[0013] Optionally, it also includes: Data is read from the verification rule base, and the candidate fault line ranking list is compared with the actual line isolation results to determine the position of the outgoing line with grounding fault in the candidate fault line ranking list. Each cumulative After a secondary ground fault, the hit rate of the first position in the candidate list of faulty lines is calculated. ; If the first-target hit rate is less than the preset target value, perform a grid search within the preset range to improve the first-target hit rate. To maximize the optimization of the weighting coefficients of the first preset time window, the second preset time window, the normalized current mutation of the outgoing line, and the phase characteristic coefficient of the outgoing line.

[0014] Optionally, it also includes: If the zero-sequence voltage of the bus is less than the differential threshold after the outgoing line is disconnected, it means that the faulty line has been successfully disconnected and the correct result is recorded. If the zero-sequence voltage of the bus is greater than the differential threshold after the outgoing line is disconnected, it indicates that the outgoing line is a non-faulty line. Then, another outgoing line is selected from the faulty line candidate sorting list to disconnect, and the operation process is recorded.

[0015] Secondly, the present invention also provides an auxiliary circuit analysis system for grounding faults in distribution networks, comprising: The data acquisition module is used to collect the zero-sequence voltage of the substation busbar and the zero-sequence current of each outgoing line in real time, and to perform preprocessing. The real-time monitoring and early warning module is used to monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset time, it is determined that a ground fault has occurred and a pop-up alarm is triggered. The analysis and ranking module is used to calculate the sudden change in the zero-sequence voltage of the bus and the sudden change in the zero-sequence current of each outgoing line at the time of grounding fault triggering. The module uses a preset sudden change algorithm to calculate the comprehensive coefficient of each outgoing line and sorts the comprehensive coefficients of each outgoing line to obtain a candidate ranking list of faulty lines. The execution instruction module is used to automatically or semi-automatically disconnect outgoing lines and isolate faulty lines based on the candidate fault line sorting list.

[0016] The beneficial effects of this invention are: The present invention provides an auxiliary circuit analysis method and system for grounding faults in power distribution networks, which has the following beneficial effects: First, this invention can realize a closed loop of the entire process from data perception to intelligent analysis, decision execution, and feedback optimization, with each module working collaboratively without the need for manual cross-system operations.

[0017] Secondly, the present invention uses a preset mutation amount algorithm to calculate the comprehensive coefficient of each outgoing line and obtain a candidate ranking list of faulty lines. The dispatcher can disconnect the line with one click or the system can execute it automatically, which greatly reduces the difficulty of decision-making.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a flowchart of an auxiliary circuit analysis method for grounding faults in power distribution networks provided in an embodiment of the present invention; Figure 2 This is another flowchart of the auxiliary circuit analysis method for grounding faults in power distribution networks provided in this embodiment of the invention; Figure 3 This is a flowchart of a method for calculating a candidate sorting list of faulty lines provided in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the calculation of mutation amount provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of an embodiment of the present invention for assisting in the analysis of grounding faults in a power distribution network. Figure 6 This is a schematic diagram of an auxiliary circuit analysis system for grounding faults in power distribution networks provided in an embodiment of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0021] Please see Figure 1 and Figure 2 , Figure 1 This is a flowchart of an auxiliary circuit analysis method for grounding faults in power distribution networks provided in an embodiment of the present invention. Figure 2 This is another flowchart of the auxiliary circuit analysis method for distribution network grounding faults provided in this invention. The auxiliary circuit analysis method for distribution network grounding faults provided by this invention includes: S101. Real-time acquisition of zero-sequence voltage of substation bus and zero-sequence current of each outgoing line, and preprocessing.

[0022] Specifically, this embodiment includes: The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are collected at a preset sampling frequency. The preset sampling frequency meets the requirements for abrupt change detection and has been calibrated for time and accuracy to ensure the synchronization of the zero-sequence voltage of the bus and the zero-sequence current of each outgoing line. The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are filtered and denoised.

[0023] For example, relying on distribution automation switch terminals (FTU, DTU), the zero-sequence voltage of the 10kV busbar in the substation is collected in real time at a sampling frequency of 128 points per cycle. and the zero-sequence current of each outgoing line related to the busbar. , Indicates the index of the outgoing line. This indicates the total number of outgoing lines; simultaneously, the collected data is filtered and denoised, and the effective value and phase angle of the data are calculated.

[0024] S102. Monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset duration, a ground fault is determined to have occurred, triggering a pop-up alarm. The bus and associated outgoing lines can be centrally displayed in the visualization interface.

[0025] Specifically, in this embodiment, the effective value of the zero-sequence voltage of the bus is calculated. With the differential threshold Compare, if And duration , If the time interval is 2s, 3s, or 4s, a ground fault is determined to have occurred, and the time of the fault is recorded. .

[0026] In this embodiment, the differentiation threshold is calculated based on the magnitude of the substation's capacitive current and the neutral point grounding method (arc suppression coil grounded or ungrounded); or, the differentiation threshold is recommended based on historical interference data.

[0027] Furthermore, the process of obtaining the differentiation threshold includes: Based on the capacitor current test report at the time of substation commissioning, the initial differential threshold is calculated using an empirical formula and expressed as follows: ; in, This represents the initial differentiation threshold, and represents the rated phase voltage of the bus (kV). For a 10kV system, the phase voltage is approximately 10 / 3 ≈ 5.77kV. This represents the voltage coefficient, and its value range is generally 0.150~0.30 (a higher value is used for arc suppression coil grounding systems, and a lower value is used for ungrounded systems). Collect data on zero-sequence voltage exceeding the limit events of all busbars within a preset time period, mark manually confirmed non-grounding fault events, and calculate the maximum zero-sequence voltage value of the busbar corresponding to the exceeding event. Update the initial differentiation threshold to: ; in, Indicates the difference threshold. This represents the initial threshold (kV) calculated using an empirical formula. This represents the maximum value (kV) of the zero-sequence voltage on the busbar among all out-of-limit events that have been manually confirmed not to be grounding faults within a preset time period (e.g., the past 30 days). The above formula indicates that the larger value between the initial threshold and 1.2 times the historical maximum interference voltage is taken to ensure that the threshold is high enough to filter out more than 80% of invalid alarms, while not being lower than the initial safety baseline. The coefficient 1.2 is an engineering experience value (with a 20% margin) and can be adjusted according to the on-site operating conditions.

[0028] The differentiation threshold is dynamically adjusted by periodic updates.

[0029] For example, all out-of-limit events in the substation within 30 days are statistically analyzed, and non-grounding fault events confirmed by manual identification (such as PT ferroresonance, three-phase imbalance of the system, etc.) are marked. The analysis is performed automatically once every quarter, and the differentiated thresholds are dynamically adjusted to ensure that the invalid alarm filtering rate is maintained above 80%.

[0030] In this embodiment, personalized voltage over-limit thresholds are configured for different power plants, effectively filtering out more than 80% of invalid alarms and ensuring that dispatchers focus on real faults.

[0031] S103. Calculate the sudden change in the zero-sequence voltage of the bus and the sudden change in the zero-sequence current of each outgoing line at the moment of ground fault triggering; use the preset sudden change algorithm to calculate the comprehensive coefficient of each outgoing line, and sort the comprehensive coefficients of each outgoing line to obtain the candidate sorting list of fault lines.

[0032] Specifically, in this embodiment, please refer to Figure 3 , Figure 3 This is a flowchart of a method for calculating a candidate fault line ranking list provided in an embodiment of the present invention. It employs a preset mutation rate algorithm to calculate the comprehensive coefficient of each outgoing line, and sorts the comprehensive coefficients of each outgoing line to obtain the candidate fault line ranking list, including: Record the trigger time of the ground fault And extract the first preset time window before the ground fault is triggered and the second preset time window after the ground fault is triggered; For each outgoing line, the zero-sequence current abrupt change is calculated based on the average zero-sequence current during the first preset time window and the average zero-sequence current during the second preset time window. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram illustrating the calculation of mutation amount provided in an embodiment of the present invention; Calculate the normalized current change of each outgoing line based on the zero-sequence current change of each outgoing line; calculate the phase characteristic coefficient of each outgoing line based on the phase difference between the zero-sequence current of each outgoing line and the zero-sequence voltage of the bus before and after the ground fault is triggered. Calculate the comprehensive coefficient of each outgoing line based on the normalized current abrupt change and phase characteristic coefficient of each outgoing line; The comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines; optionally, the candidates are sorted from largest to smallest based on their comprehensive coefficients. , This indicates the most likely faulty line, providing dispatchers with a clear basis for decision-making.

[0033] Furthermore, for each outgoing line, based on the average zero-sequence current of the first preset time window and the average zero-sequence current of the second preset time window, the zero-sequence current mutation of each outgoing line is calculated, including: Set a time window before the ground fault, i.e., the first preset time window. For example, from arrive , You can select 2 to 5 cycles; set a time window after the ground fault, i.e., the second preset time window. For example, from arrive , You can take 5 to 10 cycles.

[0034] For each outgoing line, calculate the average zero-sequence current within the first preset time window, expressed as: ; in, This represents the average zero-sequence current within the first preset time window. This represents the number of sampling points within the first preset time window, i.e., the number of sampling times, used to calculate the average value of the zero-sequence current within this window. Indicates the first preset time window. The corresponding time of the first moment Zero-sequence current of the outgoing line Indicates the index of the outgoing line. Indicates the first preset time window. Indicates the time within the first preset time window; The average zero-sequence current value within the second preset time window is calculated and expressed as: ; in, This represents the average zero-sequence current over the second preset time window. This represents the total number of sampling points within the second preset time window, used to calculate the average value of the zero-sequence current within that window. Indicates the second preset time window. The corresponding time of the first moment Zero-sequence current of the outgoing line Indicates the index of the outgoing line. This indicates the second preset time window. Indicates the time within the second preset time window; The zero-sequence current abrupt change for each outgoing line is calculated and expressed as follows: ; in, Indicates the first The sudden change in zero-sequence current of the outgoing line.

[0035] Furthermore, the normalized current abrupt change of each outgoing line is expressed as follows: ; in, Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The sudden change in zero-sequence current of the outgoing line. Indicates the first The sudden change in zero-sequence current of the outgoing line. This indicates the total number of teams that qualified.

[0036] Furthermore, the composite coefficients for each qualifying candidate are expressed as follows: ; in, Indicates the first The overall coefficient of each line is... Indicates the first Weighting coefficients for normalized current abrupt changes in outgoing lines. Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The weighting coefficients of the phase characteristic coefficients of the outgoing lines satisfy the following conditions: Optional , , Indicates the first Phase characteristic coefficient of the output line.

[0037] In this embodiment, based on the phase difference between the zero-sequence current of the outgoing line after a ground fault and the zero-sequence voltage of the bus, under normal circumstances, the phase difference between the ground fault line and the unground fault line is significantly different. The zero-sequence current of the outgoing line of the ground fault line... Zero-sequence voltage of the bus The phase difference is close to 0° or 180°, and the zero-sequence current of the outgoing line of the ungrounded fault line is... Zero-sequence voltage of the bus The phase difference is close to 90°. If the phase difference is within... or Within the range, phase characteristic coefficients ,otherwise, , This indicates the allowable deviation angle, which can be 30° or 35°.

[0038] Traditional methods, based on steady-state zero-sequence current amplitude comparisons, are prone to failure or misjudgment when the zero-sequence current changes in each outgoing line are minimal during high-resistance grounding faults. This leads to prolonged grounding faults, increasing the risk of electric shock and wildfires. In this embodiment, the abrupt changes in the zero-sequence voltage of the busbar and the zero-sequence current of each outgoing line are deeply integrated. Based on the principle that the zero-sequence current increases near the fault point, high-resistance grounding faults can be effectively detected, and the line selection accuracy can be improved to over 80%, achieving high sensitivity and precise location. At the same time, based on time-domain abrupt change calculations, no complex frequency domain transformations are required, and the sorting of all lines can be completed within seconds, meeting real-time requirements.

[0039] This embodiment also includes: A verification rule base is constructed to record the trigger time of grounding faults, the waveform of zero-sequence current of each outgoing line, the candidate ranking list of faulty lines, the actual disconnected lines, and the change of zero-sequence voltage of the bus after disconnection. The rules in the verification rule base include rules to prevent false tripping (e.g., lines that have been disconnected in the last 10 minutes are prohibited from being disconnected again), rules to prevent failure to trip (whether the zero-sequence voltage of the bus disappears after disconnection), remote control permission verification, and communication status verification.

[0040] This embodiment also includes: Data is read from the verification rule base, and the candidate fault line ranking list is compared with the actual line isolation results to determine the position of the outgoing line with grounding fault in the candidate fault line ranking list. Each cumulative After a secondary ground fault, the hit rate of the first position in the candidate list of faulty lines is calculated. ; optional For 40 / 50 / 60 times; If the first hit rate is less than the preset target value, it is within the preset range (e.g., , First preset time window Zhou Bo, Second Preset Time Window Perform a grid search to improve the first-hand hit rate. To maximize the optimization of the weighting coefficients of the first preset time window, the second preset time window, the normalized current mutation of the outgoing line, and the phase characteristic coefficient of the outgoing line; optionally, the preset target value is 70% or 70%.

[0041] The strategy verification record of this embodiment records the results of each line pull, supports accuracy statistics and algorithm parameter optimization, making the system more and more accurate with use.

[0042] S104. Based on the candidate fault line sorting list, automatically or semi-automatically disconnect the outgoing line to isolate the faulty line.

[0043] Specifically, in this embodiment, it interfaces with the remote control interface of the power distribution automation system and supports two working modes: First, semi-automatic mode (confirmed by the dispatcher); the dispatcher issues a remote control command based on the candidate fault line ranking list and the suggested line to be pulled.

[0044] Second, fully automatic mode: After safety verification, the system automatically issues a disconnect command to cut off the faulty line and feeds back the action results to the dispatcher interface.

[0045] This embodiment also includes: If the zero-sequence voltage of the bus is less than the differential threshold after the outgoing line is disconnected, it means that the faulty line has been successfully disconnected and the correct result is recorded. If the zero-sequence voltage of the bus is greater than the differential threshold after the outgoing line is disconnected, it indicates that the outgoing line is a non-faulty line. Then, another outgoing line is selected from the faulty line candidate sorting list to disconnect, and the operation process is recorded.

[0046] In summary, the auxiliary circuit analysis method for grounding faults in power distribution networks provided by this invention has the following beneficial effects: First, considering that the existing line selection device, alarm system and line pulling execution system are independent of each other and do not form a closed loop, the dispatcher needs to switch between multiple systems. This invention realizes a closed loop of the whole process from data perception to intelligent analysis to decision execution to feedback optimization. Each module works together and there is no need for manual cross-system operation.

[0047] Secondly, considering that existing systems only output a single route selection result or do not output a sorting result, and cannot provide a reliability sorting list, dispatchers still face decision uncertainty; this invention uses a preset mutation amount algorithm to calculate the comprehensive coefficient of each outgoing line and obtain a candidate sorting list of faulty lines. Dispatchers can disconnect lines with one click or the system can execute it automatically, which greatly reduces the difficulty of decision-making.

[0048] Third, the existing system uses a fixed voltage threshold, which cannot adapt to the operating characteristics of different plants and stations, resulting in a large number of invalid alarms and the drowning out of key fault information; the present invention configures personalized voltage over-limit thresholds for different plants and stations, effectively filtering more than 80% of invalid alarms and ensuring that dispatchers focus on real faults.

[0049] Fourth, existing automatic circuit-pulling schemes lack safety verification logic to prevent accidental operation and refusal to operate, posing a risk of accidentally pulling non-faulty circuits. This embodiment sets up dual safety verification protection, with built-in safety verification rules to prevent accidental operation and refusal to operate. Before automatic circuit-pulling, it verifies remote control permissions, communication status, repeated circuit-pulling conditions, etc., to ensure operational safety.

[0050] In an optional embodiment of the present invention, please refer to Figure 5 , Figure 5This is a schematic diagram of an auxiliary circuit analysis for grounding faults in a distribution network provided by an embodiment of the present invention. The auxiliary circuit analysis for grounding faults in a distribution network is achieved through the following process, specifically including: S1. Data Acquisition and Preprocessing.

[0051] Specifically, the data sensing layer collects the zero-sequence voltage of the substation busbar in real time. and the zero-sequence current of each outgoing line The terminal is time-stamped and uploaded to the intelligent analysis layer.

[0052] S2. Real-time monitoring and grounding fault identification.

[0053] Specifically, the effective value of the zero-sequence voltage of the bus is monitored in real time. With the differential threshold The comparison results.

[0054] if And the duration is greater than the preset value. If a ground fault is detected, a pop-up alarm is triggered, directly reaching the dispatcher's control window and recording the time of the ground fault. .

[0055] S3, Intelligent Analysis and Sorting.

[0056] Specifically, the preset window data before and after the ground fault is extracted, and the normalized current change of each outgoing line is calculated. and phase characteristic coefficients Further calculate the comprehensive coefficient The faulty lines are sorted and a sorted list of candidate faulty lines is output. The visual interface displays the sorting results in a list format, highlighting the first candidate route.

[0057] S4. Safety verification.

[0058] Specifically, the candidate list for faulty lines is sorted. The first candidate route in China underwent safety verification; inspection Check if a route has been executed within the last 10 minutes to prevent duplicate route execution. Check if the remote control permission status is normal. Check if the communication status is online. If all the above checks pass, execute S5; if they fail, proceed with the next check. This continues until all candidate lines in the fault line candidate sorting list have been verified.

[0059] S5, pull the road to execute.

[0060] Specifically, when the system is in semi-automatic mode, a pop-up window prompts the dispatcher to confirm. After the dispatcher clicks "Confirm Route", the command is issued.

[0061] When the system is in fully automatic mode, it automatically issues road traction commands without requiring manual confirmation.

[0062] After the circuit breaker command is issued, the system delays for 5 seconds and then reads the zero-sequence voltage of the bus again. .

[0063] S6. Result verification and recording.

[0064] Specifically, if after pulling the road, If the ground fault is successfully isolated, the result is recorded as correct; otherwise, after disconnecting the circuit... If the line is determined to be non-faulty, then it is selected from the candidate faulty line list. Perform the routing and record the operation process for subsequent statistical analysis and algorithm optimization.

[0065] S7, self-optimizing iteration.

[0066] Specifically, the system automatically calculates the total number of grounding events, automatic trigger rate, first-hit rate, top three-hit rate, and average isolation time weekly / monthly. If the first-hit rate is lower than the target value (e.g., 75%), the trigger parameters are optimized, and the weight coefficients in the intelligent judgment and sorting module are adjusted. , or time window length , The updated parameters will take effect automatically and will be used for subsequent analysis.

[0067] In one optional embodiment of the present invention, the specific implementation of a power supply bureau is described as follows: Taking a 35kV substation of a power supply bureau as an example, the 10kV busbar of this substation is an arc suppression coil grounding system with a total of 12 outgoing lines. This system has been deployed and is operational, and its configuration includes: 1. Initial value of the differentiation threshold The initial phase voltage was 25% (approximately 14.4 kV), which was adjusted to 22% phase voltage after adaptive optimization. For 2 cycles, For 5 cycles, , , .

[0068] 2. The semi-automatic working mode is adopted, and the dispatcher needs to confirm the route.

[0069] 3. The safety verification rule is to avoid repeated circuit testing within 10 minutes.

[0070] With a sampling frequency of 128 points per cycle, The system detected the zero-sequence voltage of the bus. The voltage rises to 15.2kV and remains there for 5 seconds, triggering a ground fault alarm. A pop-up window on the visualization interface displays "10kV Section I busbar ground fault." Calculate the zero-sequence current surge of each outgoing line, for example, the outgoing line... Zero-sequence current mutation It is 2.3A, outgoing line Zero-sequence current mutation It is 1.8A, outgoing line Zero-sequence current mutation The zero-sequence current surge is 0.4A, and the zero-sequence current surge of the other outgoing lines is less than 0.3A. Calculate the phase characteristic coefficient of each outgoing line. The zero-sequence current and the zero-sequence voltage of the busbar have a phase difference of 175°. Qualifying The phase difference between the zero-sequence current and the zero-sequence voltage of the bus is 168°. The phase difference between the zero-sequence current of the remaining outgoing lines and the zero-sequence voltage of the bus is approximately 85°~95°. ; Calculate the comprehensive coefficients for each qualifying line, expressed as follows: ; ; ; The intelligent analysis and sorting module outputs a sorted list: ( ), ( ), other lines ( The dispatcher views the sorting list and clicks... The corresponding "One-Click Draw" button. The system performs a security check. After verifying that remote control permissions are normal, communication is online, and no circuit has been tripped within the past 10 minutes, the circuit tripping command is issued. The zero-sequence voltage of the busbar after circuit tripping is then... The voltage dropped to 0.5kV, and the fault isolation was successful. The entire process took approximately 55 seconds, and the system automatically recorded the event and its outcome.

[0071] After one year of operation, the system's automatic trigger rate was 80.77%, the first hit rate was 81.6%, and the average fault isolation time was reduced from 15 minutes to 1 minute. The system has cumulatively reduced the fault troubleshooting time of maintenance personnel by approximately 386.5 hours and reduced the number of households experiencing power outages by approximately 10,162.5 hours.

[0072] Based on the same inventive concept, please refer to Figure 6 , Figure 6This is a schematic diagram of an auxiliary circuit analysis system for distribution network grounding faults provided in an embodiment of the present invention. The present invention also provides an auxiliary circuit analysis system for distribution network grounding faults, used to implement the auxiliary circuit analysis method for distribution network grounding faults provided in the above embodiments of the present invention. Embodiments of the method can be referred to above and will not be repeated here. The system includes: The data acquisition module 201 is used to acquire the zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line in real time, and to perform preprocessing. The real-time monitoring and early warning module 202 is used to monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset time, it is determined that a ground fault has occurred and a pop-up alarm is triggered. The analysis and ranking module 203 is used to calculate the sudden change in the zero-sequence voltage of the bus and the sudden change in the zero-sequence current of each outgoing line at the time of grounding fault triggering; it uses a preset sudden change algorithm to calculate the comprehensive coefficient of each outgoing line and sorts the comprehensive coefficients of each outgoing line to obtain a candidate ranking list of fault lines. The execution instruction module 204 is used to automatically or semi-automatically disconnect the outgoing line and cut off the faulty line according to the candidate faulty line sorting list.

[0073] Specifically, the power distribution network grounding fault auxiliary circuit analysis system provided by this invention has the following beneficial effects: First, considering that the existing line selection device, alarm system and line pulling execution system are independent of each other and do not form a closed loop, the dispatcher needs to switch between multiple systems. This invention realizes a closed loop of the whole process from data perception to intelligent analysis to decision execution to feedback optimization. Each module works together and there is no need for manual cross-system operation.

[0074] Secondly, considering that existing systems only output a single route selection result or do not output a sorting result, and cannot provide a reliability sorting list, dispatchers still face decision uncertainty; this invention uses a preset mutation amount algorithm to calculate the comprehensive coefficient of each outgoing line and obtain a candidate sorting list of faulty lines. Dispatchers can disconnect lines with one click or the system can execute it automatically, which greatly reduces the difficulty of decision-making.

[0075] Third, the existing system uses a fixed voltage threshold, which cannot adapt to the operating characteristics of different plants and stations, resulting in a large number of invalid alarms and the drowning out of key fault information; the present invention configures personalized voltage over-limit thresholds for different plants and stations, effectively filtering more than 80% of invalid alarms and ensuring that dispatchers focus on real faults.

[0076] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0077] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0078] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for auxiliary circuit analysis of grounding faults in distribution networks, characterized in that, include: The zero-sequence voltage of the substation busbar and the zero-sequence current of each outgoing line are collected in real time and preprocessed. Monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset time, a ground fault is determined to have occurred, triggering a pop-up alarm. Calculate the sudden change in zero-sequence voltage of the bus and the sudden change in zero-sequence current of each outgoing line at the moment of ground fault triggering. Using a preset mutation rate algorithm, the comprehensive coefficient of each outgoing line is calculated, and the comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines. Based on the candidate fault line sorting list, the outgoing lines are disconnected automatically or semi-automatically to isolate the faulty lines.

2. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 1, characterized in that, Real-time acquisition of zero-sequence voltage of the substation busbar and zero-sequence current of each outgoing line, followed by preprocessing, including: The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are collected at a preset sampling frequency. The zero-sequence voltage of the substation bus and the zero-sequence current of each outgoing line are filtered and denoised.

3. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 1, characterized in that, Using a pre-defined mutation rate algorithm, the comprehensive coefficient of each outgoing line is calculated, and the comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines, including: Record the trigger time of the ground fault And extract the first preset time window before the ground fault is triggered and the second preset time window after the ground fault is triggered; For each outgoing line, the zero-sequence current abrupt change is calculated based on the average zero-sequence current of the first preset time window and the average zero-sequence current of the second preset time window. Calculate the normalized current change of each outgoing line based on the zero-sequence current change of each outgoing line; calculate the phase characteristic coefficient of each outgoing line based on the phase difference between the zero-sequence current of each outgoing line and the zero-sequence voltage of the bus before and after the ground fault is triggered. Calculate the comprehensive coefficient of each outgoing line based on the normalized current abrupt change and phase characteristic coefficient of each outgoing line; The comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines.

4. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 3, characterized in that, The normalized current abrupt change of each outgoing line is expressed as follows: ； in, Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The sudden change in zero-sequence current of the outgoing line. Indicates the first The sudden change in zero-sequence current of the outgoing line. This indicates the total number of teams that qualified.

5. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 3, characterized in that, The comprehensive coefficient for each exit line is expressed as follows: ； in, Indicates the first The overall coefficient of each line is... Indicates the first Weighting coefficients for normalized current abrupt changes in outgoing lines. Indicates the first Normalized current abrupt change in the outgoing line Indicates the first The weighting coefficient of the phase characteristic coefficient of the outgoing line. Indicates the first Phase characteristic coefficient of the output line.

6. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 1, characterized in that, The process of obtaining the differentiation threshold includes: Based on the magnitude of the substation's capacitive current, the initial differentiation threshold is calculated using an empirical formula, expressed as: ； in, Indicates the initial differentiation threshold. Indicates the rated phase voltage of the busbar. Indicates the voltage coefficient; Collect data on zero-sequence voltage exceeding the limit events of all busbars within a preset time period, mark manually confirmed non-grounding fault events, and calculate the maximum zero-sequence voltage value of the busbar corresponding to the exceeding event. Update the initial differentiation threshold to: ； in, Indicates the difference threshold. Indicates the initial threshold. This represents the maximum value of the zero-sequence voltage at the busbar; The differentiation threshold is dynamically adjusted by periodic updates.

7. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 1, characterized in that, Also includes: A verification rule base is constructed to record the trigger time of grounding faults, the waveform of zero-sequence current of each outgoing line, the candidate ranking list of faulty lines, the actual disconnection line, and the change of zero-sequence voltage of the bus after disconnection; wherein, the rules of the verification rule base include rules for preventing false operation, rules for preventing refusal to operate, remote control permission verification, and communication status verification.

8. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 7, characterized in that, Also includes: Data is read from the verification rule base, and the candidate fault line sorting list is compared with the actual line isolation results to determine the position of the outgoing line with a ground fault in the candidate fault line sorting list. Each cumulative After a secondary ground fault, the hit rate of the first position in the candidate list of faulty lines is calculated. ; If the first-position hit rate is less than a preset target value, a grid search is performed within a preset range to improve the first-position hit rate. To maximize the optimization of the weighting coefficients of the first preset time window, the second preset time window, the normalized current mutation of the outgoing line, and the phase characteristic coefficient of the outgoing line.

9. The auxiliary circuit analysis method for grounding faults in distribution networks according to claim 1, characterized in that, Also includes: If the zero-sequence voltage of the bus is less than the differential threshold after the outgoing line is disconnected, it indicates that the faulty line has been successfully disconnected, and the correct result is recorded. If the zero-sequence voltage of the bus is greater than the differential threshold after the outgoing line is disconnected, it indicates that the outgoing line is a non-faulty line. Then, another outgoing line is selected from the faulty line candidate sorting list to be disconnected, and the operation process is recorded.

10. A system for auxiliary circuit analysis of grounding faults in a power distribution network, characterized in that, include: The data acquisition module is used to collect the zero-sequence voltage of the substation busbar and the zero-sequence current of each outgoing line in real time, and to perform preprocessing. The real-time monitoring and early warning module is used to monitor the zero-sequence voltage of each substation bus. When the zero-sequence voltage of the bus exceeds the differential threshold and continues for a preset time, a ground fault is determined to have occurred, triggering a pop-up alarm. The analysis and sorting module is used to calculate the sudden change in the zero-sequence voltage of the bus and the sudden change in the zero-sequence current of each outgoing line at the moment of grounding fault triggering. Using a preset mutation rate algorithm, the comprehensive coefficient of each outgoing line is calculated, and the comprehensive coefficients of each outgoing line are sorted to obtain a candidate list of faulty lines. The execution instruction module is used to automatically or semi-automatically disconnect the outgoing line from the candidate fault line sorting list.

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