An intelligent detection and early warning system for live transformer grounding flat steel

Abstract

The present application relates to the technical field of power distribution transformer grounding state monitoring, and discloses a kind of live intelligent detection and early warning system of transformer grounding flat steel, including scene modeling module, state rail module, trajectory screening module and risk early warning module;Scene modeling module establishes grounding source mapping and constructs contact path weight, state rail module obtains grounding flat steel state trajectory, trajectory screening module establishes live trajectory discriminant code table and filters contact effective discharge segment, and risk early warning module carries out contact risk conversion according to contact path weight to contact effective discharge segment, obtains contact risk grade, and carries out grounding flat steel live early warning.The present application can reduce false alarm caused by normal backflow, transient impact and induced electric field, improve grounding flat steel live early warning accuracy.

Description

Technical Field

[0001] This invention relates to the field of power distribution transformer grounding status monitoring technology, specifically a live intelligent detection and early warning system for transformer grounding flat steel. Background Technology

[0002] The grounding flat steel of a transformer is an exposed conductor in the grounding path of a pole-mounted distribution transformer. Abnormal energization of the grounding flat steel can pose a risk of electric shock to personnel and livestock on site. Traditional detection methods often rely on manual inspection, power outage testing, grounding resistance testing, single voltage testing, or single current threshold alarms. While these methods can detect some obvious anomalies, they are insufficient in distinguishing between the source of energization and the actual risk of contact.

[0003] However, in pole-mounted distribution transformers in agricultural and pastoral areas, the low-voltage neutral point repeated grounding, transformer casing grounding, and surge arrester grounding are often connected to the same exposed grounding flat steel lead-down section. The area around the grounding flat steel lead-down section is easily affected by rain, snow, thawing, mud, and livestock activity. In this case, the electric field and current responses on the grounding flat steel may simultaneously include normal return current, casing discharge, surge arrester transient impulses, and induced electric field components. When existing technologies rely on a single voltage or current threshold, they are prone to misjudging normal return current or transient induction as dangerously live, and they easily overlook the contact risk created by continuous discharge and a damp ground surface. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent detection and early warning system for the energized flat steel of a transformer, in order to solve the problem that the response of multiple grounding sources is mixed in the lead-down section of the exposed grounding flat steel shared by pole-mounted distribution transformers in agricultural and pastoral areas, which makes it difficult for existing single threshold detection to accurately identify the risk of effective discharge.

[0005] To achieve the above objectives, on the one hand, the present invention provides an intelligent detection and early warning system for live grounding flat steel of transformers, the system comprising: The scenario modeling module is used to obtain the common grounding lead information of the pole-mounted distribution transformer. Based on the connection status of the low-voltage neutral point repeated grounding, transformer shell grounding and surge arrester grounding converging to the same exposed grounding flat steel lead section, a grounding source mapping is established. The exposed length, grounding end position and grounding end water content of the exposed grounding flat steel lead section are obtained, and the contact path weight is constructed.

[0006] The state tracing module is used to collect the electric field response sequence and grounding flat steel current sequence of the exposed grounding flat steel lead-down section through a non-contact voltage sensing probe and an open-type current transformer, and to obtain the low-voltage side load imbalance sequence. The electric field response sequence, grounding flat steel current sequence and low-voltage side load imbalance sequence are time-aligned according to the same sampling time. The sampling point sequence composed of the sampling time and the aligned electric field response value, grounding flat steel current value and low-voltage side load imbalance value is used as the state trajectory of the grounding flat steel.

[0007] The trajectory filtering module is used to establish a energized trajectory discrimination code table based on the grounding source mapping. The energized trajectory discrimination code table is a lookup table that records the correspondence between segment type codes and source processing codes. The module performs state encoding and continuous same code merging on the grounding flat steel state trajectory according to the segment type code to obtain load following segments, continuous discharge segments, impact fall segments, and electric field suspension segments, and matches source processing codes for each segment. The module performs source suppression on the load following segments, impact fall segments, and electric field suspension segments according to the source processing codes, and performs contact effectiveness screening on the continuous discharge segments to obtain contact effective discharge segments.

[0008] The risk warning module is used to calculate the contact risk of the effective discharge segment based on the contact path weight, obtain the contact risk level, and provide an early warning of the grounding flat steel becoming live.

[0009] Furthermore, the scene modeling module includes: The down-lead positioning module is used as a coordinate reference to obtain the coordinates of the low-voltage neutral point repeated grounding connection point, transformer shell grounding connection point, surge arrester grounding connection point, non-contact voltage sensing probe installation position, open-type current transformer sleeve position, and the position coordinates of the down-lead of the exposed grounding flat steel section on the exposed grounding flat steel down-lead section.

[0010] A current detection section is established based on the conductor section between the sheathing position of the open-type current transformer and the grounding end of the exposed grounding flat steel lead-down section. An electric field sensing section is established on the exposed grounding flat steel lead-down section based on the installation position of the non-contact voltage sensing probe and the preset sensing extension distance.

[0011] Based on the positional relationships between the low-voltage neutral point repeated grounding connection point, the transformer shell grounding connection point, and the surge arrester grounding connection point and the current detection section and the electric field sensing section, respectively, a grounding source mapping is established.

[0012] Furthermore, the guide positioning module includes: The attribution marking module is used to mark the grounding connection point located on the side of the open-type current transformer that is away from the grounding end of the exposed grounding flat steel lead-down section and flows through the current detection section to the grounding end of the exposed grounding flat steel lead-down section as the source of current flow.

[0013] Grounding access points that fall within the electric field sensing section and are connected by a continuous conductor between the access point and the installation location of the non-contact voltage sensing probe are marked as sources of electric field proximity.

[0014] Based on the current flow source and the electric field proximity source, establish a mapping of grounding sources between the low-voltage neutral point repeated grounding, transformer shell grounding, surge arrester grounding, and the exposed grounding flat steel lead-down section.

[0015] Furthermore, the scene modeling module includes: The path quantization module is used to divide the exposed contact segments in the exposed grounding flat steel down-lead section according to the exposed length, and to calculate the exposed contact weight according to the proportion of the length of the exposed contact segment to the total length of the exposed grounding flat steel down-lead section.

[0016] The adjacent area of ​​the in-ground end is delineated based on the location of the in-ground end. The distance between the geometric center of the adjacent area of ​​the in-ground end and the lower end of the exposed contact section is obtained. The positional relationship quantity is calculated based on the ratio of the distance to the size of the adjacent area of ​​the in-ground end. The soil compaction of the adjacent area of ​​the in-ground end is obtained. The in-ground adjacency weight is calculated based on the positional relationship quantity and the soil compaction.

[0017] A continuous sampling sequence of surface water content around the ingress point is obtained. Based on the water content change range and water content retention duration in the continuous sampling sequence, conduction hysteresis is determined to obtain the stable surface conduction level. The surface conduction weight is then calculated based on the stable surface conduction level.

[0018] The exposed contact weight, the underground adjacency weight, and the surface conduction weight are combined into a contact path weight using predetermined weighting coefficients.

[0019] Furthermore, the path quantization module includes: The hysteresis determination module is used to take the discrete levels divided according to the surface water content of the surrounding land end as the surface conduction level, and determine the surface conduction level corresponding to the current water content based on the comparison result of the current water content of the continuous sampling sequence and the preset water content limit.

[0020] When the change in water content exceeds a preset change threshold and the duration of water content retention exceeds a preset duration threshold, the surface conductivity level corresponding to the current water content state will be used as the new surface conductivity level for the adjacent area at the ingress end.

[0021] When the magnitude of water content change and the duration of water content retention do not simultaneously meet the conditions, the current surface conductivity level of the adjacent area at the ingress end remains unchanged.

[0022] Furthermore, the trajectory filtering module includes: The code table configuration module is used to configure load following processing codes based on the low-voltage neutral point repeated grounding source in the grounding source mapping, discharge retention processing codes based on the transformer shell grounding source, impulse suppression processing codes based on the surge arrester grounding source, and induction suppression processing codes based on the electric field induction characteristics of the non-contact voltage sensing probe.

[0023] The electric field background state, electric field super-background state, and electric field sudden rise and fall state are set according to the electric field response sequence. The current background state, current super-background state, and short-time current response state are set according to the grounding flat steel current sequence. The load stable state and load imbalance rising state are set according to the low-voltage side load imbalance sequence.

[0024] The intersection of the load imbalance rising state and the electric field exceeding the background state is marked as the load following segment type code; the intersection of the load stable state, the electric field exceeding the background state and the current exceeding the background state is marked as the continuous discharge segment type code; the intersection of the electric field sudden rise and fall state and the short-time current response state is marked as the impact fall segment type code; and the intersection of the load stable state, the electric field exceeding the background state and the current background state is marked as the electric field suspension segment type code.

[0025] Associating the load following segment type code with the load following processing code, associating the continuous discharge segment type code with the discharge retention processing code, associating the impact fall segment type code with the impact suppression processing code, and associating the electric field suspension segment type code with the induction suppression processing code, yields a charged trajectory discrimination code table that includes segment type codes and source processing codes.

[0026] Furthermore, the trajectory filtering module includes: The segment forming module is used to match the electric field state, current state, and load state at each sampling moment in the grounded flat steel state trajectory with the energized trajectory discrimination code table to obtain the candidate type code at the sampling moment.

[0027] When there are multiple candidate sampling time type codes at the same sampling time, the primary sampling time type code is determined in the order of impact fall segment type code, continuous discharge segment type code, load following segment type code, and electric field suspension segment type code.

[0028] Based on the correlation between the primary type code at the sampling time and the electrified trajectory discrimination code table, the primary type code at the sampling time is matched with the source processing code at the sampling time.

[0029] Samples with the same primary type code at the sampling time, the same source processing code at the sampling time, and continuous sampling time are merged into an initial same code segment.

[0030] Based on the source processing code, interrupt segments located between two initial same code segments with the same sampling time main type code and the same sampling time source processing code, and whose duration is less than the preset minimum interrupt duration, are bridged to obtain the bridged same code segment.

[0031] Based on the response time difference between the state transition time of the electric field response sequence and the state transition time of the grounding flat steel current sequence, the start and end boundaries of the bridging same code segment are corrected to obtain the load following segment, continuous discharge segment, impact fall segment and electric field suspension segment.

[0032] Furthermore, the fragment forming module includes: The same-source bridging module is used to set the suppression processing code set, which includes load following processing code, impact suppression processing code and induction suppression processing code.

[0033] Search for the broken segment group consisting of the first initial homocode segment, the interrupt segment, and the second initial homocode segment in chronological order. The first initial homocode segment and the second initial homocode segment have the same primary type code at the same sampling time.

[0034] Under the following conditions: the source processing codes of the sampling points within the interrupt segment all belong to the set of suppression processing codes; the duration of the interrupt segment is less than the preset minimum interrupt duration; and the first initial same code segment and the second initial same code segment have the same source processing code, the interrupt segment is marked as a same-source bridging segment.

[0035] The first initial co-code segment, the co-source bridging segment, and the second initial co-code segment are merged to obtain the bridging co-code segment.

[0036] Furthermore, the trajectory filtering module includes: The discharge screening module is used to extract the neutral point return reference quantity from the load following segment according to the load following processing code; extract the transient suppression time window from the impact fall segment according to the impact suppression processing code; and extract the electric field induced background quantity from the electric field suspension segment according to the induction suppression processing code.

[0037] The anomaly detection background range of the continuous discharge segment is corrected based on the neutral point return reference quantity, the electric field induction background quantity, and the transient suppression time window; the trajectory segments in the continuous discharge segment that exceed the corrected anomaly detection background range and do not fall within the transient suppression time window are selected as contact effective discharge segments.

[0038] Furthermore, the leakage screening module includes: The background correction module is used to correct the current background range of the continuous discharge segment based on the neutral point return current reference amount to obtain the return current corrected current background range; to correct the electric field background range of the continuous discharge segment based on the electric field induced background amount to obtain the induced electric field corrected electric field background range; and to mark the trajectory segment in the continuous discharge segment that overlaps with the transient suppression time window as the transient shielding segment.

[0039] Based on the background range of the reflux correction current, the background range of the induced correction electric field, and the transient shielding segment, the corrected anomaly determination background range of the continuous discharge segment is obtained.

[0040] Compared with the prior art, the beneficial effects of the present invention are: 1. By mapping grounding sources, weighting contact paths, identifying the state trajectory of grounding flat steel and the energized trajectory, the electric field response, current response of the grounding flat steel, and the unbalanced load state on the low-voltage side are correlated and identified. This transforms the early warning target from being triggered by a single voltage or current threshold to identifying the effective discharge segment and outputting the contact risk level. This reduces false alarms caused by normal neutral point return current, induced electric field, and transient impacts of surge arresters, and improves the accuracy of early warning for energized grounding flat steel of pole-mounted distribution transformers in agricultural and pastoral areas.

[0041] 2. By prioritizing the primary type code at the sampling time, merging initial same code segments, bridging from the same source, and correcting the start and end boundaries, the segment conflicts, short-term breaks, and sensor response time differences caused by the convergence of multiple grounding sources in the same exposed grounding flat steel down conductor are processed. This ensures that the continuous discharge segment is not fragmented by short-term load following, electric field suspension, or impact falling segments, thus maintaining the temporal continuity of the effective discharge process and providing a more stable trajectory basis for subsequent contact risk calculation. Attached Figure Description

[0042] Figure 1 This is a block diagram of a live intelligent detection and early warning system for transformer grounding flat steel according to the present invention. Detailed Implementation

[0043] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Before providing examples, it is necessary to describe the application scenarios of this invention. This invention is applicable to the scenario of monitoring the live grounding flat steel of pole-mounted distribution transformers in agricultural and pastoral areas. The low-voltage neutral point repeated grounding, transformer shell grounding, and surge arrester grounding are connected to the same exposed grounding flat steel down section. The exposed grounding flat steel down section has an accessible exposed section. The grounding end is surrounded by surface environments that affect the conductivity of the contact path, such as rain, snow, thawing, mud, livestock staying or drinking water. It is necessary to identify the live state with contact risk without interrupting power or dismantling the grounding conductor.

[0045] Example 1: A 10kV / 0.4kV, 200kVA pole-mounted distribution transformer is configured in the T-23 substation of an agricultural and pastoral area. The low-voltage neutral point repeated grounding, transformer casing grounding, and surge arrester grounding are all connected to the same exposed grounding flat steel downlead section. The exposed grounding flat steel downlead section uses 40mm×4mm galvanized flat steel with an exposed length of 2.40m. Starting from the grounding point at the end of the exposed grounding flat steel downlead section, a position coordinate system is established upwards along the exposed grounding flat steel downlead section.

[0046] The installation position of the open-type current transformer is 0.36m, and the installation position of the non-contact voltage sensing probe is 1.40m. The low-voltage neutral point repeated grounding connection point is 1.50m, the transformer shell grounding connection point is 1.42m, and the surge arrester grounding connection point is 1.82m. The conductor section from 0.00m to 0.36m between the installation position of the open-type current transformer and the grounding flat steel lead-down end is designated as the current detection section. The conductor section 0.20m above and below the installation position of the non-contact voltage sensing probe is designated as the electric field sensing section, which ranges from 1.20m to 1.60m.

[0047] The low-voltage neutral point repeated grounding connection point, transformer shell grounding connection point, and surge arrester grounding connection point are all located on the side of the open-type current transformer sheathing location away from the grounding flat steel lead-down section's grounding end. Furthermore, the conductor paths from all three grounding connection points to the grounding flat steel lead-down section's grounding end pass through the current detection section. The low-voltage neutral point repeated grounding connection point, transformer shell grounding connection point, and surge arrester grounding connection point are all marked as current-through sources. The low-voltage neutral point repeated grounding connection point and transformer shell grounding connection point are located within the electric field sensing section and are marked as electric field proximity sources. The shortest conductor distance between the surge arrester grounding connection point and the electric field sensing section is 0.22m. The surge arrester grounding connection point does not fall within the electric field sensing section and is not marked as an electric field proximity source. The surge arrester grounding connection point is a current-through source and corresponds to the impulse suppression processing code in the live trajectory discrimination code table.

[0048] The exposed contact section ranges from 0.18m to 1.38m, with a total length of 1.20m. Exposed contact weight. .

[0049] The distance between the geometric center of the underground entry point's adjacent area and the lower end of the exposed contact section is 0.18m. The size of the underground entry point's adjacent area is taken as a radius of 0.80m. (Positional relationship quantity) .

[0050] The soil compaction in the area adjacent to the underground entry point is a parameter recorded during installation, measured by a portable soil compaction meter, and updated quarterly. The soil compaction measured in the T-23 transformer station is 0.78 MPa. The lower limit of soil compaction is taken as 0.30 MPa, the upper limit as 1.20 MPa, and the soil compaction normalization value. .

[0051] The adjacent weights are calculated based on location relationship (0.60) and soil compaction normalization value (0.40). The values ​​of the positional relationship quantity and the normalized value of soil compaction are based on the following: the geometric proximity between the adjacent area of ​​the grounding end and the lower end of the exposed contact section directly affects the length of the surface return path when personnel or livestock come into contact with the lower section of the exposed grounding flat steel. Soil compaction affects the contact stability and water retention capacity of the adjacent area of ​​the grounding end. The influence of geometric proximity on the formation of the contact path has a higher weight than that of soil compaction.

[0052] Surface conductivity level is a discrete level classified according to the surface water content of the surrounding area at the entry point, and the surface conductivity level is distinguished according to a preset water content limit. In this embodiment, a surface water content of not more than 20% is recorded as low conductivity level, a surface water content of more than 20% but less than 30% is recorded as medium conductivity level, and a surface water content of not less than 30% is recorded as high conductivity level. The current water content of the continuous sampling sequence is compared with the preset water content limit to determine the surface conductivity level corresponding to the current water content.

[0053] A shallow soil moisture sensor was installed in the adjacent area of ​​the ground-entry point, at a depth of 8 cm, with a sampling period of 10 minutes. The volumetric moisture contents at 14:00, 14:10, 14:20, 14:30, and 14:40 were 18%, 19%, 34%, 35%, and 36%, respectively. The moisture content change was calculated as the difference between the median of the current three consecutive sampling values ​​and the stable median before the switch. The stable median before the switch was 19%, and the median of the current three consecutive sampling values ​​was 35%, resulting in a moisture content change of 16%. The preset change threshold was 8%, and the preset duration threshold was 15 minutes. From 14:20 to 14:40, the volumetric moisture content remained above 30%, with a moisture content retention time of 20 minutes. If the moisture content change exceeded the preset change threshold and the moisture content retention time exceeded the preset duration threshold, the surface conductivity level of the adjacent area of ​​the ground-entry point was switched to a high conductivity level. The surface conductivity weight corresponding to the high conductivity level is denoted as […]. , .

[0054] The predetermined weighting coefficients for exposed contact weight, underground adjacency weight, and surface connectivity weight are 0.30, 0.30, and 0.40, respectively, and the contact path weight is... The contact path weight is rounded to two decimal places and is set to 0.69.

[0055] The electric field response sequence output by the non-contact voltage sensing probe is denoted as... The unit is V. The electric field response sequence is the output voltage of the non-contact voltage sensing probe conditioning circuit and is not used as the direct value of the voltage to ground of the exposed grounding flat steel lead section. The grounding flat steel current sequence output by the open-type current transformer is denoted as... The unit is mA. The low-voltage side three-phase current comes from the existing distribution transformer monitoring terminal in the transformer substation area. The low-voltage side three-phase current is denoted as follows: , , The low-voltage side load imbalance sequence is denoted as... The calculation formula is ,in .

[0056] The sampling period for non-contact voltage sensing probes, open-type current transformers, and existing distribution transformer monitoring terminals in the distribution area is all set to 1 second. Sampling values ​​with a sampling time deviation of no more than 0.5 seconds are grouped into the same sampling time; when the continuous missing duration is no more than 3 seconds, the missing values ​​are linearly interpolated according to adjacent sampling values ​​before and after the missing value; when the continuous missing duration is greater than 3 seconds, the corresponding time period is not included in the status coding. Each sampling point in the grounding flat steel status trajectory is recorded as follows: .

[0057] The period from 14:20:00 to 14:21:59 is designated as the background statistical period. The background median of the electric field response sequence is 0.09V, and the background standard deviation is 0.015V; the background median of the grounding flat steel current sequence is 10mA, and the background standard deviation is 2mA. The electric field background state is set as follows: Where 0.15V equals the background median of the electric field response sequence plus four times the background standard deviation. The electric field exceeding the background state is defined as... The electric field surge and fall condition is defined as an electric field response increment greater than 0.70V within 1 second, and a decrease in electric field response greater than 60% of the surge peak within 5 seconds. The current background condition is defined as follows: Where 16mA equals the background median of the grounding flat steel current sequence plus three times the background standard deviation. The current exceeding the background value is set as... The duration is greater than 5 seconds, where 60mA equals the background median of the grounding flat steel current sequence plus 25 times the background standard deviation. The short-time current response state is set as follows: And the duration shall not exceed 8 seconds, where 500mA is equal to 5 times the reference value of the 100mA warning current. The load stable state is set to... And the change within 60 seconds should not exceed 0.03. The load imbalance rising state is set as follows: And the increment within 60 seconds is greater than 0.10.

[0058] The low-voltage neutral point repeated grounding source is configured with load following processing code F1; the transformer shell grounding source is configured with discharge retention processing code F2; the surge arrester grounding source is configured with impulse suppression processing code F3; and the electric field induction characteristics of the non-contact voltage sensing probe are configured with induction suppression processing code F4. The intersection of the load imbalance rising state and the electric field exceeding background state is marked as load following segment type code C1. The intersection of the load stable state, the electric field exceeding background state, and the current exceeding background state is marked as continuous discharge segment type code C2. The intersection of the electric field sudden rise and fall state and the short-time current response state is marked as impulse fall segment type code C3. The intersection of the load stable state, the electric field exceeding background state, and the current background state is marked as electric field suspension segment type code C4. C1 is associated with F1, C2 with F2, C3 with F3, and C4 with F4. Using the segment type code as the lookup key and the source processing code corresponding to the segment type code as the lookup result, a charged trajectory discrimination code table is formed.

[0059] From 14:22:00 to 14:22:50, It increased from 0.12 to 0.34. The median is 0.31V. The median is 52mA, and the candidate type code at the sampling time is C1. (14:23:05 to 14:23:09) The peak voltage was 1.86V, which dropped to 0.22V within 5 seconds. The peak value was 2700mA, the duration was 4s, and the candidate type code at the sampling time was C3. The peak value of the grounding flat steel current sequence of 2700mA is the equivalent peak value after the sampling link of the open-type current transformer is limited, and does not represent the actual peak value of the surge arrester's discharge current. (14:23:20 to 14:23:49) Maintain a value between 0.12 and 0.14. The median is 0.82V. The median was 162mA, and the candidate type code at the sampling time was C2. (14:23:50 to 14:23:53) Keep it at 0.13. The median is 0.76V. The median was 14mA, and the candidate type code at the sampling time was C4. (14:23:54 to 14:24:45) Maintain a value between 0.12 and 0.15. The median is 0.81V. The median was 158mA, and the candidate type code at the sampling time was C2. (14:25:10 to 14:25:25) Keep it at 0.11. The median is 0.34V. The median is 11mA, and the candidate type code at the sampling time is C4.

[0060] When multiple candidate type codes exist at the same sampling time, the primary type code for the sampling time is selected in the order of C3, C2, C1, and C4. Sampling points with the same primary type code, the same source processing code, and consecutive sampling times are merged into an initial same-code segment. From 14:23:20 to 14:23:49, the first initial same-code segment is formed, with the primary type code for the sampling time being C2 and the source processing code for the sampling time being F2. From 14:23:50 to 14:23:53, an interrupt segment is formed, with the primary type code for the sampling time being C4 and the source processing code for the sampling time being F4. From 14:23:54 to 14:24:45, the second initial same-code segment is formed, with the primary type code for the sampling time being C2 and the source processing code for the sampling time being F2.

[0061] The suppression processing code set is {F1, F3, F4}. The discharge retention processing code F2 is not added to the suppression processing code set, and the continuous discharge segment is retained as an object for contact validity screening. The preset minimum interruption duration is 5 seconds. The interruption segment from 14:23:50 to 14:23:53 lasts for 4 seconds. The sampling time source processing codes of the sampling points within the interruption segment all belong to the suppression processing code set. The first initial same-code segment and the second initial same-code segment have the same sampling time primary type code C2, and the first initial same-code segment and the second initial same-code segment have the same source processing code F2. The interruption segment from 14:23:50 to 14:23:53 is marked as a same-source bridging segment. The first initial same-code segment, the same-source bridging segment, and the second initial same-code segment are merged into a bridging same-code segment.

[0062] Within the bridging code segment, the state transition time of the electric field response sequence entering the electric field over-background state is 14:23:19, and the state transition time of the grounding flat steel current sequence entering the current over-background state is 14:23:20. The response time difference is denoted as the state transition time of the grounding flat steel current sequence entering the corresponding state minus the state transition time of the electric field response sequence entering the corresponding state; the response time difference is +1s, and a positive value indicates that the electric field response sequence transitions before the grounding flat steel current sequence. The starting boundary of the bridging code segment is taken as the earlier of the state transition times of the electric field response sequence and the grounding flat steel current sequence, resulting in 14:23:19. The state transition time of the electric field response sequence exiting the electric field over-background state is 14:24:47, and the state transition time of the grounding flat steel current sequence exiting the current over-background state is 14:24:45. The later of the state transition times of the electric field response sequence and the grounding flat steel current sequence exiting the corresponding state is taken as the end boundary of the bridging segment, resulting in 14:24:47. After boundary correction, 14:22:00 to 14:22:50 is recorded as the load following segment, 14:23:05 to 14:23:09 as the impact fall segment, 14:23:19 to 14:24:47 as the continuous discharge segment, and 14:25:10 to 14:25:25 as the electric field suspension segment.

[0063] The neutral point return current reference is measured as the 90th percentile of the grounding flat current sequence within the load-following segment, which is 55 mA. The transient suppression time window is taken as 3 seconds beyond the start and end times of the impact fall segment, from 14:23:02 to 14:23:12. The electric field induced background is measured as the difference between the median of the electric field response sequence and the median of the background electric field response sequence within the electric field suspension segment. .

[0064] The current background range of the continuous discharge segment is 0mA to 16mA. The upper limit of the return current background range is 16mA plus 55mA, and the return current background range is 0mA to 71mA. The electric field background range of the continuous discharge segment is 0V to 0.15V. The upper limit of the induced electric field background range is 0.15V plus 0.25V, and the induced electric field background range is 0V to 0.40V. The trajectory segment overlapping with 14:23:02 to 14:23:12 in the continuous discharge segment is marked as a transient shielding segment. The continuous discharge segment from 14:23:19 to 14:24:47 does not overlap with the transient suppression time window, and the transient shielding segment is empty.

[0065] Within the continuous discharge segment, for anomalies exceeding the corrected background threshold, a rule is applied where both current and electric field conditions are simultaneously satisfied. The current condition is... The electric field condition is The periods from 14:23:20 to 14:23:49 and from 14:23:54 to 14:24:47 both meet the criteria of exceeding the corrected anomaly detection background range and not falling within the transient suppression window. The period from 14:23:50 to 14:23:53 retains the same-source bridging marker and is not included in the over-limit duration. The effective discharge segment is recorded from 14:23:19 to 14:24:47, of which 14:23:50 to 14:23:53 is the same-source bridging segment, which is not included in the over-limit duration. The over-limit sub-segments of the effective discharge segment are from 14:23:20 to 14:23:49 and from 14:23:54 to 14:24:47. Based on the interval caliber including the start time and excluding the end time, the over-limit duration of the effective discharge segment is 82 seconds.

[0066] The median current sequence of the grounding flat steel within the effective discharge segment is 160mA, and the median electric field response sequence is 0.81V. The normalized value for current exceeding the limit is calculated based on the 100mA warning current reference value and the upper limit of the return current correction background range. The electric field over-limit normalization value is calculated based on the 1.00V electric field reference value and the upper limit of the induced correction electric field background range. The duration normalization value is calculated based on a 60-second reference duration. .

[0067] Exposure risk conversion score .

[0068] The risk level of contact is level three. The risk level of contact is level two. The contact risk level was Level 1. At 14:24:47, T-23 received a Level 1 contact risk warning. The recorded information for the grounding flat steel energized warning was as follows: Distribution area T-23, contact risk level Level 1, median grounding flat steel current sequence 160mA, median electric field response sequence 0.81V, effective discharge segments from 14:23:19 to 14:24:47, bridging segment from 14:23:50 to 14:23:53, and over-limit segments from 14:23:20 to 14:23:49 and 14:23:54 to 14:24:47.

[0069] Finally, it should be noted that although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A live intelligent detection and early warning system for transformer grounding flat steel, characterized in that, The system includes: The scene modeling module is used to obtain the common grounding lead information of the pole-mounted distribution transformer, and establish a grounding source mapping based on the connection status of the low-voltage neutral point repeated grounding, transformer shell grounding and surge arrester grounding converging to the same exposed grounding flat steel lead section; obtain the exposed length of the exposed grounding flat steel lead section, the location of the grounding end and the water content of the ground surface around the grounding end, and construct the contact path weight; The state-tracking module is used to collect the electric field response sequence and grounding flat steel current sequence of the exposed grounding flat steel lead-down section through a non-contact voltage sensing probe and an open-type current transformer, and to obtain the low-voltage side load imbalance sequence. The electric field response sequence, grounding flat steel current sequence and low-voltage side load imbalance sequence are time-aligned according to the same sampling time. The sampling point sequence composed of the sampling time and the aligned electric field response value, grounding flat steel current value and low-voltage side load imbalance value is used as the state trajectory of the grounding flat steel. The trajectory filtering module is used to establish a energized trajectory discrimination code table based on the grounding source mapping. The energized trajectory discrimination code table is a lookup table that records the correspondence between segment type codes and source processing codes. The module performs state encoding and continuous same code merging on the grounding flat steel state trajectory according to the segment type code to obtain load following segments, continuous discharge segments, impact fall segments, and electric field suspension segments, and matches source processing codes for each segment. The module performs source suppression on the load following segments, impact fall segments, and electric field suspension segments according to the source processing codes, and performs contact effectiveness filtering on the continuous discharge segments to obtain contact effective discharge segments. The risk warning module is used to calculate the contact risk of the effective discharge segment based on the contact path weight, obtain the contact risk level, and provide an early warning of the grounding flat steel becoming live.

2. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 1, characterized in that, The scene modeling module includes: The down-lead positioning module is used as a coordinate reference to obtain the coordinates of the low-voltage neutral point repeated grounding connection point, transformer shell grounding connection point, surge arrester grounding connection point, non-contact voltage sensing probe installation position, open-type current transformer sleeve position, and the position coordinates of the down-lead of the exposed grounding flat steel section on the exposed grounding flat steel section. A current detection section is established based on the conductor section between the sleeve position of the open-type current transformer and the grounding end of the exposed grounding flat steel lead-down section. An electric field sensing section is established on the exposed grounding flat steel lead-down section based on the installation position of the non-contact voltage sensing probe and the preset sensing extension distance. Based on the positional relationships between the low-voltage neutral point repeated grounding connection point, the transformer shell grounding connection point, and the surge arrester grounding connection point and the current detection section and the electric field sensing section, respectively, a grounding source mapping is established.

3. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 2, characterized in that, The guide positioning module includes: The attribution marking module is used to mark the grounding connection point located on the side of the open-type current transformer that is away from the grounding end of the exposed grounding flat steel lead-down section and flows through the current detection section to the grounding end of the exposed grounding flat steel lead-down section as the source of current flow. The grounding access point that falls within the electric field sensing section and is connected to the non-contact voltage sensing probe installation location by a continuous conductor is marked as the electric field proximity source. Based on the current flow source and the electric field proximity source, establish a mapping of grounding sources between the low-voltage neutral point repeated grounding, transformer shell grounding, surge arrester grounding, and the exposed grounding flat steel lead-down section.

4. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 1, characterized in that, The scene modeling module includes: The path quantization module is used to divide the exposed contact segments in the exposed grounding flat steel down-lead section according to the exposed length, and to calculate the exposed contact weight according to the proportion of the length of the exposed contact segment to the total length of the exposed grounding flat steel down-lead section. The adjacent area of ​​the in-ground end is delineated based on the location of the in-ground end. The distance between the geometric center of the adjacent area of ​​the in-ground end and the lower end of the exposed contact section is obtained. The positional relationship quantity is calculated based on the ratio of the distance to the size of the adjacent area of ​​the in-ground end. The soil compaction of the adjacent area of ​​the in-ground end is obtained. The in-ground adjacency weight is calculated based on the positional relationship quantity and the soil compaction. A continuous sampling sequence of surface water content around the ingress end is obtained. Based on the water content change range and water content retention time in the continuous sampling sequence, conduction hysteresis is determined to obtain the stable surface conduction level, and the surface conduction weight is calculated based on the stable surface conduction level. The exposed contact weight, the underground adjacency weight, and the surface conduction weight are combined into a contact path weight using predetermined weighting coefficients.

5. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 4, characterized in that, The path quantization module includes: The hysteresis determination module is used to take the discrete levels divided according to the surface water content of the surrounding land end as the surface conduction level, and determine the surface conduction level corresponding to the current water content based on the comparison result of the current water content of the continuous sampling sequence and the preset water content limit. When the change in water content exceeds the preset change threshold and the duration of water content retention exceeds the preset duration threshold, the surface conductivity level corresponding to the current water content state will be used as the new surface conductivity level of the adjacent area at the ingress end. When the magnitude of water content change and the duration of water content retention do not simultaneously meet the conditions, the current surface conductivity level of the adjacent area at the ingress end remains unchanged.

6. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 1, characterized in that, The trajectory filtering module includes: The code table configuration module is used to configure load following processing codes based on the low-voltage neutral point repeated grounding source in the grounding source mapping, discharge retention processing codes based on the transformer shell grounding source, impulse suppression processing codes based on the surge arrester grounding source, and induction suppression processing codes based on the electric field induction characteristics of the non-contact voltage sensing probe. The electric field background state, electric field super-background state, and electric field sudden rise and fall state are set according to the electric field response sequence. The current background state, current super-background state, and short-time current response state are set according to the grounding flat steel current sequence. The load stable state and load imbalance rising state are set according to the low-voltage side load imbalance sequence. The intersection of the load imbalance rising state and the electric field exceeding the background state is marked as the load following segment type code; the intersection of the load stable state, the electric field exceeding the background state and the current exceeding the background state is marked as the continuous discharge segment type code; the intersection of the electric field sudden rise and fall state and the short-time current response state is marked as the impact fall segment type code; and the intersection of the load stable state, the electric field exceeding the background state and the current background state is marked as the electric field suspension segment type code. Associating the load following segment type code with the load following processing code, associating the continuous discharge segment type code with the discharge retention processing code, associating the impact fall segment type code with the impact suppression processing code, and associating the electric field suspension segment type code with the induction suppression processing code, yields a charged trajectory discrimination code table that includes segment type codes and source processing codes.

7. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 6, characterized in that, The trajectory filtering module includes: The segment forming module is used to match the electric field state, current state and load state at each sampling moment in the grounded flat steel state trajectory with the energized trajectory discrimination code table to obtain the candidate type code at the sampling moment; When there are multiple candidate type codes for the same sampling time, the main type code for the sampling time is determined in the order of impact fall segment type code, continuous discharge segment type code, load following segment type code, and electric field suspension segment type code. Based on the correlation between the main type code of the sampling time and the electrified trajectory discrimination code table, the sampling time source processing code is matched to the main type code of the sampling time; Sampling points with the same main type code at the sampling time, the same source processing code at the sampling time, and continuous sampling time are merged into an initial same code segment; Based on the source processing code, interrupt segments located between two initial same code segments with the same sampling time main type code and the same sampling time source processing code, and whose duration is less than the preset minimum interrupt duration, are bridged to obtain the bridged same code segment. Based on the response time difference between the state transition time of the electric field response sequence and the state transition time of the grounding flat steel current sequence, the start and end boundaries of the bridging same code segment are corrected to obtain the load following segment, continuous discharge segment, impact fall segment and electric field suspension segment.

8. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 7, characterized in that, The fragment forming module includes: The same-source bridging module is used to set the suppression processing code set, which includes load following processing code, impact suppression processing code and induction suppression processing code; Search for the broken segment group consisting of the first initial homocode segment, the interrupt segment, and the second initial homocode segment in chronological order. The first initial homocode segment and the second initial homocode segment have the same primary type code at the same sampling time. Under the following conditions: the source processing codes of the sampling points within the interrupt segment all belong to the set of suppression processing codes, the duration of the interrupt segment is less than the preset minimum interrupt duration, and the first initial same code segment and the second initial same code segment have the same source processing code, the interrupt segment is marked as a same-source bridging segment. The first initial co-code segment, the co-source bridging segment, and the second initial co-code segment are merged to obtain the bridging co-code segment.

9. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 8, characterized in that, The trajectory filtering module includes: The discharge screening module is used to extract the neutral point return current reference amount from the load following segment according to the load following processing code; extract the transient suppression time window from the impact fall segment according to the impact suppression processing code; and extract the electric field induced background amount from the electric field suspension segment according to the induction suppression processing code. The anomaly detection background range of the continuous discharge segment is corrected based on the neutral point return reference quantity, the electric field induction background quantity, and the transient suppression time window; the trajectory segments in the continuous discharge segment that exceed the corrected anomaly detection background range and do not fall within the transient suppression time window are selected as contact effective discharge segments.

10. The intelligent detection and early warning system for live grounding flat steel of transformers according to claim 9, characterized in that, The leakage screening module includes: The background correction module is used to correct the current background range of the continuous discharge segment based on the neutral point return current reference amount to obtain the return current corrected current background range; correct the electric field background range of the continuous discharge segment based on the electric field induced background amount to obtain the induced electric field corrected electric field background range; and mark the trajectory segment in the continuous discharge segment that overlaps with the transient suppression time window as the transient shielding segment. Based on the background range of the reflux correction current, the background range of the induced correction electric field, and the transient shielding segment, the corrected anomaly determination background range of the continuous discharge segment is obtained.

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