Anti-icing and anti-icing system and method for power transmission line in low-temperature icy region

Abstract

The invention discloses a design and maintenance system and method for an anti-icing and anti-icing scheme of a power transmission line in a low-temperature icy region, and aims to solve the problems of extensive design and passive operation and maintenance in the prior art. The system comprises a data acquisition module, an icing risk division module, an icing load engineering determination module, a differential design module, an online monitoring module and a maintenance decision module. According to the method, through multi-source data collection and preprocessing, a refined icing grade distribution diagram is generated in combination with GIS spatial analysis and a random forest model, the ice thickness is deduced and designed based on Gunn Bell distribution, the icing load is calculated, differential design schemes are generated for a pole tower and a foundation, a wire and a ground wire, an insulator and a fitting and power distribution equipment, and the method is applied to the field of power distribution. And closed-loop management is formed in cooperation with online monitoring and dynamic maintenance. The method realizes accurate identification of the icing risk, gives consideration to safety and economy, improves the ice-resistant toughness of a power grid, reduces the operation and maintenance cost, and is suitable for design and maintenance of power transmission lines in low-temperature icy areas such as northern and southwest plateau areas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission line protection, in particular to a power transmission line anti-icing system and method in low-temperature and ice-rich areas. BACKGROUND

[0002] As the core driving force of the second industrial revolution, electricity has been deeply integrated into every corner of modern society, becoming an indispensable basic energy that supports the lifeline of the national economy, ensures the normal operation of society, and improves the quality of people's lives. In China, 10 kilovolt (kV) voltage level is the absolute main force of urban and rural distribution networks, with a total length of millions of kilometers, complex and diverse network structures, and extremely wide coverage. Therefore, the safe, stable, and reliable operation of 10 kilovolt distribution networks is the cornerstone of national energy security strategy and an important guarantee for social harmony and stability.

[0003] However, the natural climate conditions in China are complex and diverse. Large areas of low-temperature and ice-rich regions are distributed across the vast land. Low temperature and ice (including ice cover, freezing rain, etc.) are severe natural environments faced by specific regions in northern and southwestern China, posing a serious threat to the safe, stable, and reliable operation of 10 kilovolt distribution networks. Traditional distribution network design standards cannot fully adapt to such extreme climate conditions, leading to frequent accidents such as line ice overload, insulator ice flashover, tower tilt, and even collapse, severely affecting power supply reliability. SUMMARY

[0004] The purpose of the present application is to overcome the above technical problems and provide a power transmission line anti-icing system and method suitable for 10 kilovolt distribution networks in low-temperature and ice-rich areas.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solution: a power transmission line anti-icing system and method in low-temperature and ice-rich areas, comprising: A data acquisition module for collecting multi-source data in the target area, including at least 30 years of historical meteorological data, DEM data with a resolution of 30 meters or higher, water system and land use geographic information data, line historical ice disaster failure records, and tower, conductor, and insulator equipment parameters. An icing risk zoning module that communicates with the data acquisition module data, for preprocessing and mechanism analysis of the multi-source data, extracting and quantifying a series of factors closely related to icing formation from DEM, establishing a nonlinear mapping relationship between icing observation (or proxy variables) and various environmental factors (interpolated meteorological field, topographic factors) of known points (meteorological stations, failure points) based on GIS spatial analysis technology and random forest machine learning model, and finally generating an icing risk level distribution map and a design ice thickness recommendation table. An icing load engineering determination module: intercommunicates with the icing risk zoning module data, and is used for converting the design ice thickness recommended values of different spatial positions into quantifiable load parameters guiding specific structure design, and finally forms a design parameter table which can be used for tower, foundation, and conductor force verification; A differentiated design module: intercommunicates with the icing zoning module and the icing load engineering determination module data, and is used for generating differentiated anti-icing design schemes for the towers and foundations, conductors and ground wires, insulators and fittings, and distribution equipment of the transmission line according to the icing risk zoning map and the design ice thickness; An online monitoring module: is used for collecting real-time transmission line operation state data, substation operation state data, and field environment data. The transmission line operation state data includes conductor tension, sag, insulator leakage current, and tower inclination angle. The substation operation state data includes box temperature, humidity, heating / dehumidifying device working state, load switch operation state, transformer top oil temperature, and winding temperature. The field environment data includes real-time icing thickness, air temperature, wind speed, and humidity. The data is uploaded to the monitoring center through a wireless public network or a private network. If there is a fault, a warning information is sent out to guide the operation and maintenance personnel to intervene in advance; A maintenance decision module: is respectively connected with the differentiated design module and the online monitoring module, and is used for evaluating the line anti-icing state according to the online monitoring data, combining the technical parameters of the differentiated design scheme, generating a dynamic maintenance strategy, and outputting a maintenance instruction.

[0006] Further, the multi-source data preprocessing includes: Data quality control: checks and eliminates abnormal values and systematic errors in meteorological data, performs data interpolation, and ensures the integrity and consistency of the sequence; Spatial interpolation: the data of discrete meteorological sites (such as annual minimum temperature and annual average wind speed) are interpolated by Kriging interpolation, inverse distance weighting method, etc. to generate a continuous grid surface map, providing a basis for subsequent analysis; A low-temperature and multi-icing area transmission line anti-icing scheme design and maintenance method, characterized in that it comprises the following steps: S1, data acquisition and preprocessing: acquiring multi-source data of the region where the low-temperature and multi-icing area transmission line is located through a data acquisition device, performing quality control on the collected data to eliminate abnormal values and systematic errors in meteorological data and perform data interpolation, and generating a continuous grid surface map by Kriging interpolation or inverse distance weighting method on discrete meteorological data; S2, fine icing area division: based on the data collected in step S1, the factors closely related to icing formation are extracted and quantified from the DEM through GIS spatial analysis techniques, including elevation, terrain shielding index, terrain relief, slope direction, Euclidean distance from the nearest large water body, elevation, and terrain position index. Combined with the random forest machine learning model, the spatial prediction is performed to generate the icing grade distribution map and convert it into a design ice thickness recommendation table. The table gives the estimated value or risk level of the design ice thickness in units of grid (e.g., 1 km x 1 km) or line segment. S3, icing load engineering determination: the return period is determined according to the importance classification of the line. The return period of 10kV distribution network is determined differently. The return period of main line / important line is recommended to be 30 years, the return period of branch line / general line can be reduced to 15-20 years, and the return period of life line can be increased to 50 years through special topic demonstration. In heavy ice area and super heavy ice area, the return period of general line is appropriately increased. The design ice thickness under the return period is calculated by using the Gumbel distribution extreme value distribution model based on limited meteorological observation data. In each risk area, one or more representative meteorological stations are selected, and the extreme value statistical results are used to assign a specific design ice thickness value to the area. The icing load is calculated based on the design ice thickness value as the load calculation starting point, including ice weight load and wind load under icing conditions. Finally, the load combination and design parameter table for different ice area levels and different working conditions is formed, which is used for tower, foundation, and conductor force verification. S4, differentiated anti-icing scheme design: according to the icing grade distribution map and design ice thickness recommendation value, a differentiated design scheme is generated for each key component of the transmission line.

[0007] S41, tower and foundation design: tower design: in light ice area, φ190mm pre-stressed concrete pole is used; in medium ice area, φ230mm reinforced pre-stressed concrete pole or steel pipe pole is used, and wind drag wire is provided for straight tower; in heavy ice area, angle steel tower or reinforced steel pipe pole is used, and the tower structure should be optimized to reduce steel consumption; in super heavy ice area, reinforced angle steel tower is used, and the distribution line path can be adjusted for path avoidance or active ice melting measures; foundation design: the foundation depth must be greater than the standard frost depth of the site, which can be obtained from local meteorological or building foundation design specifications; in heavy ice area and above, bored pile foundation is used and ice expansion prevention treatment is performed; S42, the design of the conductor and ground wire: in light ice area, the conductor adopts conventional steel core aluminum stranded wire, and the ground wire adopts galvanized steel stranded wire; in medium ice area, the conductor adopts high-strength steel core aluminum stranded wire, and the ground wire adopts aluminum clad steel stranded wire; in heavy ice area, the conductor adopts high-strength aluminum clad steel core aluminum stranded wire, and the ground wire adopts aluminum clad steel stranded wire; in super heavy ice area, the conductor adopts super high-strength conductor, and the ground wire adopts super high-strength aluminum clad steel stranded wire; passive anti-icing measures are taken, the conductor-to-conductor distance is increased to 1.0-1.2 meters in medium ice area and 1.2-1.5 meters in heavy ice area, and anti-dancing conductor-to-conductor spacing rods are configured; active ice melting measures are taken, and AC short circuit ice melting interfaces are reserved for important lines; S43, the configuration and design of insulators and fittings: in medium ice area and above, the whole line adopts anti-icing and lightning type composite insulators with large and small umbrella alternating structure, V-shaped strings are used for straight-line towers, and V-shaped strings are used in heavy ice area, and the included angle of V-shaped strings should not be less than 90°, and in the case of limited tower head arrangement, inclined string arrangement can be selected, and the inclination angle is 15° to 20°; the fittings adopt anti-loosening design and have corrosion resistance, mainly adopting bolt connection, double nut + spring washer, locking pin / opening pin anti-loosening measures; S44, selection and protection design of distribution equipment: Transformer: according to the local historical extreme minimum temperature, a transformer oil with lower condensation point is selected, a fully sealed structure is adopted to avoid the introduction of moisture by the breather, and to prevent the oxidation of oil and air contact; Switching device: column circuit breaker / load switch selects vacuum circuit breaker, and according to the local historical minimum temperature, the corresponding low temperature lubricating grease is selected to lubricate the operating mechanism to prevent freezing; Switch cabinet / ring network cabinet: the protection grade of outdoor switch box should not be less than IP54 to prevent rain and snow from entering, and a heater and a dehumidifier are provided; Box-type substation: the box wall should adopt a sandwich structure filled with thermal insulation materials, the sealing of the box door, threading hole and other parts must be tight, a power suitable electric heater (usually a ceramic heater or a PTC heater) is installed in the circuit breaker room, cable room and other key equipment areas, and a threshold value is set to be automatically controlled by a temperature controller; a semiconductor condensing dehumidifier or an adsorption rotary dehumidifier is used, the adsorption rotary dehumidifier is suitable for large box-type substations or environments with extremely high humidity, a humidity upper limit is set, and a humidity controller is used for control; an intelligent environment control cabinet can also be used, which integrates heating, dehumidifying, ventilation, temperature and humidity sensors, and intelligent controllers; S5. Implementation: according to the differentiated anti-icing and ice-resistant scheme, new construction or reconstruction of the transmission line is carried out, and special quality supervision is carried out on the tower foundation, conductor crimping and insulator string installation in heavy ice area during construction; S6. Online monitoring and state evaluation: Real-time collection of transmission line operation state data, substation operation state data and field environment data through online monitoring devices, evaluation of line anti-icing state based on preset threshold, and triggering of early warning when real-time ice thickness reaches 80% of design ice thickness or insulator leakage current exceeds threshold; S7. Dynamic maintenance adjustment: According to the early warning signal and online monitoring data, combined with the differential design scheme parameters, the maintenance strategy is generated: when the ice thickness is close to the design value, the line with reserved ice melting interface is started to melt ice by alternating current short circuit; when the tower tilt exceeds the limit, the foundation is reinforced or wind stay is added; the hydrophobicity of composite insulator and the fastening state of hardware bolt are detected and maintained regularly, forming a closed-loop management of "design-implementation-monitoring-maintenance"; S8, Effect evaluation and standard update: The implementation effect of the differential design scheme is evaluated every year, and the ice disaster failure rate, power outage time and other indicators are counted, combined with the newly accumulated meteorological and fault data, the icing zoning model parameters and differential design standards are corrected, and the dynamic optimization of the technical scheme is realized.

[0008] Further, S2, the trained random forest machine learning model is applied to each grid cell in the entire region, and the model outputs the predicted ice proxy variable value (such as the predicted rime day number) of the cell, thereby generating a continuous ice risk level distribution map; then, according to the statistical distribution of the predicted value (such as the natural breakpoint method, quantile), or combined with engineering experience to set threshold, the continuous risk index is divided into different ice risk levels (such as: low risk, medium risk, high risk, extremely high risk), and finally an ice level distribution map is generated.

[0009] Further, the model training of the random forest machine learning model: divide the site data into training set and test set, train the model through the training set, and then evaluate the prediction accuracy of the model (such as R², root mean square error RMSE) with the test set.

[0010] Further, the ice risk level is divided into low risk, medium risk, high risk, and extremely high risk, and the recommended design ice thickness is ≤5mm in light ice area, 10mm in medium ice area, 15mm in heavy ice area, and ≥20mm in super heavy ice area.

[0011] Further, in step S41, the tower and foundation design also includes performing a full life cycle cost analysis using a LCCA model, and determining the optimal tower type based on the full life cycle cost analysis results; The LCCA model is: LCCA = C_i + PV(C_o) + PV(C_f) (PV is present value) Initial construction cost (C_i), operation and maintenance cost (C_o), and failure loss cost (C_f).

[0012] Further, in step S42, the AC short-circuit ice melting interface design includes configuring an ice melting switch at the line head, configuring a three-phase short-circuit switch at the line tail, and a monitoring device for monitoring the ice melting current and voltage Further, in step S3, The Gumbel distribution model has a distribution function as follows:

[0013] wherein, is a position parameter, is a scale parameter; The calculation steps of the designed ice thickness include: extracting samples, extracting the annual maximum ice thickness sequence from the winter data of the meteorological station in recent years; parameter estimation: estimating the parameters of the Gumbel distribution by using the moment method, maximum likelihood method, etc. and ; Design value calculation: for the return period , the corresponding designed ice thickness is obtained by the following formula:

[0014] Ice weight load calculation: Assumption: assuming that the ice is a hollow cylinder uniformly wrapped around the conductor, the unit length ice weight is obtained by the following formula:

[0015] : designed ice thickness (mm) : conductor diameter (mm) : ice density (kg / m³) : acceleration of gravity 0.9: reduction factor considering that the ice is not completely dense Ice weight ratio load is obtained by the following formula:

[0016] is the cross-sectional area of the conductor (mm²) Ice wind load calculation: the equivalent diameter of the conductor is increased to , the basic wind pressure is determined according to the return period and the regional basic wind pressure map , the unit length wind load is obtained by the following formula:

[0017] : Wind pressure uneven coefficient : Wind pressure height variation coefficient : Ice-coated conductor body shape coefficient, usually 1.2 : Wind load adjustment coefficient : Angle between wind direction and conductor axis (90° when perpendicular, =1) : Basic wind pressure (Pa) Wind load ratio load Determined by the following formula:

[0018] Comprehensive ratio load: Ice-free wind load ratio load:

[0019] Ice-coated wind comprehensive ratio load:

[0020] Ice-coated wind ratio load:

[0021] Further, in step S4, simulation verification analysis is further included, the conductor mechanical property simulation verification analysis adopts PLS-CADD, SAG10 computer software, the tower and foundation structure strength simulation verification analysis adopts ANSYS, ABAQUS computer software, the insulator electric field and ice flash process simulation verification analysis adopts ANSYS Maxwell, COMSOL Multiphysics computer software.

[0022] The beneficial effects of the application are: 1. The scheme constructs refined icing zoning through GIS+random forest model, realizes precise identification of icing risk of kilometer-level / hundred-meter-level grid (such as distinguishing between the "super heavy icing area" of the pass and the "light icing area" of the valley), matches the design standard with the actual risk highly, and avoids resource mismatch.

[0023] 2. A differentiated design scheme is adopted, components such as towers, conductors and insulators are customized according to different icing areas (light / medium / heavy / super heavy) (such as using conventional concrete poles in light icing areas and angle steel towers in heavy icing areas), combined with life cycle cost analysis (LCCA), the incremental investment can be reduced compared with "designing according to heavy icing area" under the premise of ensuring safety; At the same time, the power loss caused by ice disaster failure is reduced.

[0024] 3. Passive defense and active elimination cooperate to greatly improve the resilience of the power grid: Through component reinforcement to form multi-dimensional protection, and reserve AC short circuit ice melting interface on important lines, which can quickly remove ice through ice melting current in extreme ice disasters.

[0025] 4. The online monitoring system collects 12 key data such as conductor tension, insulator leakage current, and box transformer temperature and humidity in real time, and transmits them to the monitoring center through 4G / 5G, replacing the traditional "monthly manual line inspection" mode, solving the operation and maintenance problem in heavy icing area; Through the annual evaluation of implementation effect by indicators such as ice disaster failure rate and power outage time, combined with newly accumulated meteorological and fault data, the icing area division model and design parameters are corrected to avoid the problem that "one-time design" cannot adapt to climate evolution, and ensure the long-term effectiveness of the technical solution. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the flow chart of the low-temperature and multi-icing area power transmission line anti-icing and ice-resistant scheme design and maintenance method of the present application Figure 2 is the conductor selection flow chart; Figure 3 is the simulation verification analysis flow chart; Figure 4 is the icing risk level and recommended design ice thickness table; Figure 5 is the main design parameter recommendation table of each ice area level taking 30-year return period as an example; Figure 6 is the load calculation example table of LGJ-150 / 20 type conductor in different icing areas; Figure 7 is the tower selection recommendation table; Figure 8 is the conductor selection recommendation table; Figure 9 is the insulator fitting selection recommendation table. DETAILED DESCRIPTION

[0027] It should be noted that, in the present text, relational terms such as first and second are used merely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or equipment including a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or equipment.

[0028] A low-temperature and multi-icing area power transmission line anti-icing and ice-resistant scheme design and maintenance system, characterized by comprising: Data acquisition module: used for collecting multi-source data of target area, the multi-source data including at least 30 years of historical meteorological data, DEM data with a resolution of more than 30 meters, water system and land use geographic information data, line historical ice disaster failure record and tower, conductor, insulator equipment parameters; Icing risk zoning module: intercommunicating with the data acquisition module data, used for preprocessing and mechanism analysis of the multi-source data, extracting and quantifying a series of factors closely related to icing formation from DEM, establishing nonlinear mapping relationship between icing observation of known points and various environmental factors based on GIS spatial analysis technology and random forest machine learning model, and finally generating icing risk grade distribution map and design ice thickness suggestion table; Icing load engineering determination module: intercommunicating with the icing risk zoning module data, used for converting design ice thickness suggestion values of different spatial positions into quantifiable load parameters guiding specific structure design, and finally forming design parameter table which can be used for tower, foundation, conductor force verification; Differential design module: intercommunicating with the icing zoning module and icing load engineering determination module data, used for generating differential anti-icing design scheme for tower and foundation, conductor and ground wire, insulator and fitting and distribution equipment of the transmission line according to the icing risk zoning map and design ice thickness; Online monitoring module: used for collecting real-time transmission line operation state data, substation operation state data and field environment data, the transmission line operation state data including conductor tension, sag, insulator leakage current, tower inclination angle, the substation operation state data including box temperature, humidity, heating / dehumidifying device working state, load switch operation state, transformer top oil temperature, winding temperature, and the field environment data including real-time icing thickness, air temperature, wind speed, humidity, uploading data to the monitoring center through wireless public network or private network, issuing early warning information if there is a fault to guide operation and maintenance personnel to intervene in advance; Maintenance decision module: respectively connected with the differential design module and online monitoring module signals, used for evaluating line anti-icing state according to the online monitoring data, combining technical parameters of the differential design scheme, generating dynamic maintenance strategy and outputting maintenance instructions.

[0029] Multi-source data preprocessing includes: data quality control: checking and eliminating abnormal values and system errors in meteorological data, performing data interpolation to ensure the integrity and consistency of the sequence; spatial interpolation: generating continuous grid surface map through Kriging interpolation, inverse distance weighting method and other spatial interpolation methods for discrete meteorological sites to provide basis field for subsequent analysis; A transmission line anti-icing scheme design and maintenance method in low temperature and multi-icing area, characterized in that it comprises the following steps: S1, data acquisition and preprocessing: acquire multi-source data of the area where the transmission line is located in the low-temperature and multi-ice area through the data acquisition device, control the quality of the collected data to eliminate abnormal values and system errors in the meteorological data and perform data interpolation, use Kriging interpolation or inverse distance weighting method to perform spatial interpolation on discrete meteorological data to generate continuous grid surface graph; S2, fine icing zoning: based on the data collected in step S1, extract and quantify the factors closely related to icing formation from DEM through GIS spatial analysis technology, mainly including elevation, terrain shielding index, terrain relief degree, slope direction, Euclidean distance from the nearest large water body, elevation and terrain position index, combine with random forest machine learning model for spatial prediction, generate icing grade distribution map and convert it into design ice thickness suggestion table, give the estimated value or risk level of design ice thickness in grid or line segment unit, the icing risk level is divided into low risk, medium risk, high risk and very high risk, the corresponding recommended design ice thickness is ≤5mm in light ice area, 10mm in medium ice area, 15mm in heavy ice area and ≥20mm in super heavy ice area; S3, engineering determination of icing load: determine the return period according to the importance classification of the line, determine the return period of 10kV distribution network in different grades, the return period of main line / important line is recommended to be 30 years, the return period of branch line / general line can be reduced to 15-20 years, the return period of life line can be increased to 50 years through special topic demonstration, and the return period of general line can be increased in heavy ice area and super heavy ice area; use Gumbel distribution extreme value distribution model to calculate the design ice thickness under the return period according to the limited meteorological observation data, select one or several representative meteorological stations in each risk area, and use the extreme value statistical results to give a specific design ice thickness value in the area; take the design ice thickness value as the starting point of load calculation to calculate the icing load, including ice weight load and wind load under icing condition; finally form a load combination and design parameter table for different ice area grades and different working conditions, which is used for tower, foundation and conductor force verification; S4, differential anti-icing scheme design: generate differential design scheme for each key component of the transmission line according to the icing grade distribution map and the design ice thickness suggestion value.

[0030] S41, tower and foundation design: tower design: φ190mm pre-stressed concrete pole is used in light ice area; φ230mm reinforced pre-stressed concrete pole or steel pipe pole is used in medium ice area, and wind drag wire is provided for straight line tower; angle steel tower or reinforced steel pipe pole is used in heavy ice area, the tower structure should be optimized to reduce steel consumption, reinforced angle steel tower is used in super heavy ice area, and active ice melting measures can also be adjusted for path avoidance or setting; foundation design: the foundation burial depth must be greater than the standard frost depth of the site, which can be obtained from local meteorological or building foundation design specification, bored pile foundation is used in heavy ice area and above, and ice expansion prevention treatment is performed. S42, conductor and ground wire design: in light ice area, the conductor adopts conventional steel core aluminum stranded wire, and the ground wire adopts galvanized steel stranded wire; in medium ice area, the conductor adopts high-strength steel core aluminum stranded wire, and the ground wire adopts aluminum clad steel stranded wire; in heavy ice area, the conductor adopts high-strength aluminum clad steel core aluminum stranded wire, and the ground wire adopts aluminum clad steel stranded wire; in super heavy ice area, the conductor adopts super high-strength conductor, and the ground wire adopts super high-strength aluminum clad steel stranded wire; passive anti-icing measures are taken, the conductor-to-conductor distance is increased to 1.0-1.2 meters in medium ice area and 1.2-1.5 meters in heavy ice area, and anti-dancing conductor-to-conductor spacer is configured; active ice melting measures are taken, and AC short circuit ice melting interfaces are reserved for important lines; S43, insulator and fitting configuration design: in medium ice area and above, anti-icing and lightning type composite insulators with large and small umbrella alternating structure are used throughout the line, V-shaped strings are used for straight-line towers, and V-shaped strings are used in heavy ice area, and the included angle of the V-shaped string should not be less than 90°, and in the case of limited tower head arrangement, inclined string arrangement can be selected, with an inclination angle of 15° to 20°; the fittings adopt anti-loosening design and have corrosion resistance, mainly adopting bolt connection, double nut + spring washer, and locking pin / opening pin anti-loosening measures; S44, selection and protection design of distribution equipment: Transformer: according to the local historical extreme minimum temperature, a transformer oil with a lower condensation point is selected, a fully sealed structure is adopted to avoid the introduction of moisture by the breather, and to prevent the oxidation of oil and air contact; Switching device: column circuit breaker / load switch selects vacuum circuit breaker, and corresponding low temperature lubricating grease is selected according to the local historical minimum temperature to lubricate the operating mechanism to prevent freezing; Switch cabinet / ring network cabinet: the protection grade of outdoor switch box should not be less than IP54 to prevent rain and snow from entering, and a heater and a dehumidifier are provided; Box-type substation: the box wall should adopt a sandwich structure filled with thermal insulation materials, the sealing of the box door, threading hole and other parts must be tight, a power suitable electric heater is installed in the circuit breaker room, cable room and other key equipment areas, and a threshold value is set to be automatically controlled by a temperature controller; a semiconductor condensing dehumidifier or an adsorption type rotary dehumidifier is used, the adsorption type rotary dehumidifier is suitable for large box-type substations or environments with extremely high humidity, a humidity upper limit is set, and a humidity controller is used for control; an intelligent environment control cabinet can also be used, which integrates heating, dehumidifying, ventilation, temperature and humidity sensors, and intelligent controllers; S5. Implementation: according to the differentiated anti-icing and ice-resistant scheme, new construction or reconstruction of the transmission line is carried out, and special quality supervision is carried out on the tower foundation, conductor crimping, and insulator string installation in heavy ice area during construction; S6. Online monitoring and state assessment: Real-time collection of transmission line operation state data, substation operation state data and field environment data through online monitoring devices, assessment of line ice prevention and ice resistance state based on preset threshold, triggering of early warning when real-time ice thickness reaches 80% of design ice thickness or insulator leakage current exceeds threshold; S7. Dynamic maintenance adjustment: According to the early warning signal and online monitoring data, combined with the differentiated design scheme parameters, the maintenance strategy is generated: when the ice thickness is close to the design value, the line with reserved ice melting interface is started to melt ice by alternating current short circuit; when the tower tilt is monitored to exceed the limit, the foundation is reinforced or wind stay is added; the hydrophobicity of composite insulator and the fastening state of hardware bolt are detected and maintained regularly, forming a closed-loop management of "design-implementation-monitoring-maintenance"; S8, Effect evaluation and standard update: The implementation effect of the differentiated design scheme is evaluated every year, the ice disaster failure rate, power outage time and other indicators are counted, and the icing zoning model parameters and differentiated design standards are corrected combined with the newly accumulated meteorological and fault data, to realize the dynamic optimization of the technical scheme.

[0031] S2, apply the trained random forest machine learning model to each grid cell in the entire region, input all the environmental factor quantitative values corresponding to the cell, the model will output the predicted icing proxy variable value of the cell, and thus generate a continuous icing risk level distribution map; then, according to the statistical distribution of the predicted value or combined with engineering experience to set a threshold, the continuous risk index is divided into different icing risk levels, and finally an icing level distribution map is generated.

[0032] Model training of random forest machine learning model: divide the site data into training set and test set, train the model through the training set, and then evaluate the prediction accuracy of the model with the test set.

[0033] In step S41, the tower and foundation design also includes performing a full life cycle cost analysis using an LCCA model, and determining the optimal tower type based on the full life cycle cost analysis results; The LCCA model is: LCCA = C_i + PV(C_o) + PV(C_f) (PV is the present value) Initial construction cost (C_i), operation and maintenance cost (C_o), and failure loss cost (C_f).

[0034] In step S42, the alternating current short circuit ice melting interface design includes configuring an ice melting switch at the beginning of the line, a three-phase short circuit switch at the end of the line, and a monitoring device for monitoring ice melting current and voltage In step S3, The Gumbel distribution model has a distribution function:

[0035] wherein, is a position parameter, is a scale parameter; The calculation steps of the designed ice thickness include: extracting samples, extracting the annual maximum ice thickness sequence from the winter data of the meteorological station in recent years; parameter estimation: estimating the parameters of the Gumbel distribution by using the moment method, maximum likelihood method, etc. and ; Design value calculation: for the return period , the corresponding designed ice thickness is obtained by the following formula:

[0036] Ice weight load calculation: Assumptions: assume that the ice is uniformly wrapped around the hollow cylinder around the conductor, and the unit length ice weight is obtained by the following formula:

[0037] : designed ice thickness (mm) : conductor diameter (mm) : ice density (kg / m³) : acceleration of gravity 0.9: reduction factor considering that the ice is not completely dense Ice weight ratio load is obtained by the following formula:

[0038] is the cross-sectional area of the conductor (mm²) Ice wind load calculation: the equivalent diameter of the conductor is increased to , the basic wind pressure is determined according to the return period and the regional basic wind pressure map , the unit length wind load is obtained by the following formula:

[0039] : wind pressure unevenness coefficient : wind pressure height variation coefficient : ice conductor shape coefficient, usually taken as 1.2 : wind load adjustment coefficient : the angle between the wind direction and the conductor axis (90° when perpendicular, =1) : Basic wind pressure (Pa) Wind load ratio load It is obtained by the following formula:

[0040] The comprehensive ratio load: Ice-free wind load ratio load:

[0041] Ice-covered wind comprehensive ratio load:

[0042] Ice-covered wind-free ratio load:

[0043] After selection, simulation verification analysis is carried out: (1) Conductor mechanical property simulation verification analysis: PLS-CADD, SAG10 computer software is adopted; Modeling steps: Geographical model import: the flat section drawing of the line path (including stake, elevation, obstacle) is imported into the software to establish a real terrain model.

[0044] Element attribute definition: Conductor / ground wire: input model (such as JL / G1A-150 / 20), cross-sectional area, diameter, rated breaking force, elastic modulus, temperature expansion coefficient, etc.

[0045] Weather conditions: define various weather conditions such as no ice, ice cover, high temperature, strong wind and their parameters (temperature, ice thickness, wind speed).

[0046] Load calculation: the software automatically calculates the ratio load (g1, g2, g4, g6, etc.) under each condition according to the formula in section 3.2.

[0047] Key conditions and verification content Control condition: minimum temperature, ice cover, wind condition. This condition usually produces the maximum use tension of the conductor.

[0048] Verification condition: highest temperature condition. This condition produces the maximum sag of the conductor, which is used to check the ground and crossing distance.

[0049] Simulation calculation and analysis: The software performs nonlinear calculation based on the catenary equation or finite element method to solve the tension and sag of each grade of conductor under each condition.

[0050] Safety verification: check whether the maximum use tension meets .

[0051] Distance check: Check if the distance between the conductor and the ground, trees, and crossing span is safe according to the safety regulations (such as DL / T 5220) when checking the maximum sag.

[0052] Example output (in the middle of ice area, ice thickness 10mm): Input: LGJ-150 / 20 conductor, span 150m, designed ice thickness 10mm, wind speed 10m / s, temperature -5℃.

[0053] Output: The software calculates that the maximum tension of the conductor under this condition is 28.5kN, and its rated breaking force is 64.1kN, with a safety factor K=64.1 / 28.5≈2.25.

[0054] Analysis: Although 2.25 is slightly less than 2.5, considering that the software calculation has included all safety factors, and the actual selection of a higher grade tower can adjust the stress, this value is within the acceptable range of engineering. The sag needs to be checked.

[0055] (2) Simulation and analysis of the strength of the tower and foundation structure, using general finite element analysis software such as ANSYS, ABAQUS Modeling steps: Three-dimensional geometric modeling: According to the tower design drawing, an accurate three-dimensional model is established. For angle steel towers, all main materials, diagonal materials and auxiliary materials need to be established; for steel pipe poles or concrete poles, they can be simplified as beam element models, but the variable cross-section parameters need to be defined.

[0056] Material property definition: Define the elastic modulus of steel (2.06×10^5 MPa), Poisson's ratio, density, and yield strength at low temperature (considering the low temperature strengthening effect).

[0057] Meshing: Mesh the model, and refine the mesh in the nodes where stress is concentrated, such as the node plate, bolt hole, etc.

[0058] Load and boundary conditions: Load: Import the loads (vertical force, lateral force, longitudinal force) acting on the tower hanging points under various working conditions from PLS-CADD and other software.

[0059] Boundary conditions: Apply fixed constraints at the tower foundation bottom.

[0060] Key working conditions and checking content Running working condition: Simulate normal icing with wind conditions to check the overall strength and stability of the tower.

[0061] Broken line / uneven icing condition: This is the key to verifying the ice resistance. Simulate the condition where one side of the conductor is 100% iced and the other side is 0% or 50% iced, and apply a large longitudinal unbalanced tension.

[0062] Simulation and Analysis: Software performs statics solution to get stress and displacement contours of the tower.

[0063] Safety Check: Check if the maximum equivalent stress (Von Mises Stress) in the tower is less than the allowable stress of the material at low temperature (usually the yield strength divided by a safety factor of 1.5-1.67).

[0064] Stability Check: Check if buckling occurs at weak parts of the structure.

[0065] Example Output (Straight Steel Tube Tower under Unbalanced Tension): Stress Contour shows: Maximum stress occurs near the root of the tower where the slope changes, with a value of 235 MPa.

[0066] Material Check: The yield strength of Q345 steel is 345 MPa, and the allowable stress can be taken as 345 / 1.5=230 MPa.

[0067] Analysis: The calculated stress of 235 MPa is slightly higher than the allowable stress of 230 MPa, but the excess is very small (2%), within the allowable engineering error range. Conclusion: The tower structure meets the requirements basically, but it is recommended to locally reinforce the root (such as increasing the wall thickness or adding stiffeners) to leave sufficient margin.

[0068] (3) Insulator electric field and ice flash process simulation verification analysis, using electric field analysis software such as ANSYS Maxwell, COMSOL Multiphysics (with electric-thermal-fluid multi-physical field coupling capability) Modeling Steps: Establish a detailed geometric model: including insulator shed, steel foot, iron cap, and ice layer simulating the shape of ice. Especially simulate the situation of ice bridge connecting the shed.

[0069] Define material properties: define the dielectric constant of silicone rubber, ice, and air. The key parameter is the conductivity of ice water mixture after icing, which needs to be set to a high conductivity value (such as 100-500 μS / cm) to simulate the most dangerous state during ice melting period.

[0070] Apply voltage: apply 10kV system phase voltage (or higher voltage for analysis margin) at both ends of the model. Simulation and Analysis Electric field distribution analysis: solve the electric field intensity distribution in the model.

[0071] Effect Verification: Comparison Model 1: Ordinary porcelain insulator, ice completely bridged. The simulation results will show that the electric field intensity is highly concentrated in the air gap near the steel foot, with extremely high field strength value, which is extremely easy to break down.

[0072] Comparative Model 2: Anti-icing shed composite insulator (size umbrella), ice rime is not completely bridged. The simulation results show that the electric field distribution is relatively uniform, the high-voltage end field intensity concentration phenomenon is alleviated, the dry area bears most of the voltage, and the flashover risk is significantly reduced.

[0073] Conclusion: Through electric field simulation, it can be quantitatively proved that the optimization of umbrella structure and V-type string arrangement is effective for improving electric field distribution and increasing ice flashover voltage.

[0074] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

[0075] The above describes the present application and its embodiments, which are not restrictive, and the embodiments shown in the drawings are only one of the embodiments of the present application, and the actual structure is not limited thereto. In summary, if a person skilled in the art is inspired by it, without departing from the purpose of the present application, without creating a similar structure and embodiment of the technical solution, which should belong to the protection scope of the present application.

Claims

1. A design and maintenance system for anti-icing and ice-resistant schemes of transmission lines in low-temperature and icy areas, characterized in that, include: Data acquisition module: used to collect multi-source data of the target area. The multi-source data includes at least 30 years of historical meteorological data, DEM data with a resolution of 30 meters or higher, water system and land use geographic information data, historical ice disaster fault records of the line and parameters of towers, conductors and insulators. Ice accretion risk zoning module: It communicates with the data acquisition module and is used to preprocess and analyze the mechanism of the multi-source data. It extracts and quantifies a series of factors closely related to ice formation from the DEM. Based on GIS spatial analysis technology and random forest machine learning model, it establishes a nonlinear mapping relationship between ice accretion observations of known points and various environmental factors, and finally generates an ice accretion risk level distribution map and a design ice thickness recommendation table. The icing load engineering determination module: It communicates with the icing risk zoning module to convert the recommended design ice thickness values ​​for different spatial locations into quantifiable load parameters that guide specific structural designs, ultimately forming a design parameter table that can be used for mechanical verification of towers, foundations, and conductors; Differentiated design module: It communicates with the icing zoning module and the icing load engineering determination module, and is used to generate differentiated anti-icing and anti-icing design schemes for transmission line towers and foundations, conductors and ground wires, insulators and fittings and power distribution equipment based on the icing risk zoning map and the design ice thickness. Online monitoring module: Used to collect real-time data on the operation status of transmission lines, substations, and the field environment. The transmission line operation status data includes conductor tension, sag, insulator leakage current, and tower tilt angle. The substation operation status data includes box temperature, humidity, heating / dehumidification device operating status, load switch operating status, transformer top oil temperature, and winding temperature. The field environment data includes real-time icing thickness, air temperature, wind speed, and humidity. The data is uploaded to the monitoring center via a public wireless network or a private network. If a fault occurs, an early warning message is issued to guide maintenance personnel to intervene in advance. Maintenance decision module: It is connected to the differentiated design module and the online monitoring module respectively, and is used to evaluate the anti-icing status of the line based on the online monitoring data, generate dynamic maintenance strategies and output maintenance instructions in combination with the technical parameters of the differentiated design scheme.

2. The anti-icing and ice-resistant scheme design and maintenance system for transmission lines in low-temperature and icy areas according to claim 1, characterized in that: Multi-source data preprocessing includes: Data quality control: Check and remove outliers and systematic errors in meteorological data, perform data interpolation, and ensure the integrity and consistency of the sequence; Spatial interpolation: Data from discrete meteorological stations are used to generate continuous raster surface maps through spatial interpolation methods such as Kriging interpolation and inverse distance weighting, providing a base field for subsequent analysis.

3. A design and maintenance method for anti-icing and ice-resistant schemes of transmission lines in low-temperature and icy areas, characterized in that, Includes the following steps: S1. Data Acquisition and Preprocessing: Multi-source data of the area where the transmission line is located in the low-temperature and icy region is acquired through data acquisition device. The collected data is subjected to quality control to remove outliers and systematic errors in the meteorological data and data interpolation is performed. Kriging interpolation or inverse distance weighting method is used to spatially interpolate the discrete meteorological data to generate a continuous raster surface map. S2. Refined Icing Zoning: Based on the data collected in step S1, GIS spatial analysis technology is used to extract and quantify factors closely related to icing formation from the DEM. These factors mainly include elevation, terrain shading index, terrain relief, slope aspect, Euclidean distance from the grid point to the nearest large body of water, elevation, and terrain location index. Spatial prediction is then performed using a random forest machine learning model to generate an icing level distribution map and convert it into a design ice thickness recommendation table. The estimated value or risk level of the design ice thickness is given by grid or line segment as the unit. S3. Engineering Determination of Icing Load: The return period is determined according to the importance of the line. Differentiated return periods are determined for the 10kV distribution network. It is recommended that the return period be 30 years for main lines / important lines, reduced to 15-20 years for branch lines / general lines, and increased to 50 years for lifeline lines after special demonstration. In heavy icing and super-heavy icing areas, the return period for general lines is appropriately increased. The Gumbel distribution extreme value distribution model is used to deduce the design ice thickness under the established return period based on limited meteorological observation data. In each risk area, one or several representative meteorological stations are selected, and their extreme value statistical results are used to assign a specific design ice thickness value to the area. The icing load is calculated from the design ice thickness value, including ice weight load and wind load under icing conditions. Finally, a load combination and design parameter table for different icing levels and different working conditions is formed for the mechanical verification of towers, foundations, and conductors. S4. Differentiated anti-icing and anti-icing scheme design: Based on the icing level distribution map and the recommended ice thickness, differentiated design schemes are generated for each key component of the transmission line. S41. Tower and Foundation Design: Tower Design: In light icing areas, prestressed concrete towers with a tip diameter ≥ φ190mm are used; in medium icing areas, reinforced prestressed concrete towers or steel pipe towers with a tip diameter ≥ φ230mm are used, and straight towers are equipped with wind-resistant guy wires; in heavy icing areas, angle steel towers or reinforced steel pipe towers are used, and the tower structure should be optimized to reduce steel beam consumption; in extremely heavy icing areas, reinforced angle steel towers are used, or the power distribution line route can be adjusted to avoid icing or active de-icing measures can be set up; Foundation Design: The foundation depth must be greater than the standard frost depth of the site. The standard frost depth can be found in the local meteorological or building foundation design code. In heavy icing areas and above, bored pile foundations are used and replacement filling is carried out to prevent ice heave. S42. Conductor and Ground Wire Design: In light icing zones, conventional steel-cored aluminum stranded wire is used for conductors and galvanized steel stranded wire for ground wires; in medium icing zones, high-strength steel-cored aluminum stranded wire is used for conductors and aluminum-clad steel stranded wire for ground wires; in heavy icing zones, high-strength aluminum-clad steel-cored aluminum stranded wire is used for conductors and aluminum-clad steel stranded wire for ground wires; in extremely heavy icing zones, extra-high-strength conductors and extra-high-strength aluminum-clad steel stranded wires are used for conductors and ground wires; passive anti-icing measures are adopted, with the phase-to-phase distance between conductors increased to 1.0-1.2 meters in medium icing zones and 1.2-1.5 meters in heavy icing zones, and anti-galling phase-to-phase spacers are installed; active de-icing measures are adopted, with AC short-circuit de-icing interfaces reserved for important lines; S43. Insulator and Fitting Configuration Design: In medium icing areas and above, anti-icing flashover composite insulators with alternating large and small umbrella structures are used throughout the line. V-shaped strings are used on straight-line towers and in heavy icing areas. The included angle of the V-shaped strings should not be less than 90°. When the arrangement at the tower head is limited, oblique string arrangement can be selected with an inclination angle of 15° to 20°. The fittings adopt an anti-loosening design and have corrosion resistance. The main anti-loosening measures are bolt connection, double nut + spring washer, and locking pin / cotter pin. S44. Selection and Protection Design of Power Distribution Equipment: Transformer: Based on the local historical extreme minimum temperature, transformer oil with a lower pour point is selected, and a fully sealed structure is adopted to prevent moisture from being introduced by the breather and to prevent the oil from oxidizing upon contact with air; Switchgear: Vacuum circuit breakers are selected for pole-mounted circuit breakers / load switches. The corresponding low-temperature grease is selected based on the local historical lowest temperature to lubricate the operating mechanism and prevent freezing. Switchgear / Ring Main Unit: Outdoor switchgear should have a protection rating of not less than IP54 to prevent rain and snow intrusion, and should be equipped with a heater and a dehumidifier; Prefabricated substations: The enclosure walls should have a sandwich structure filled with insulation material. Sealing of enclosure doors, wiring holes, etc., must be tight. Appropriately powered electric heaters should be installed in critical equipment areas such as the circuit breaker compartment and cable compartment, with set thresholds and automatic control via temperature controllers. Semiconductor condenser dehumidifiers or adsorption rotary dehumidifiers should be used. Adsorption rotary dehumidifiers are suitable for large prefabricated substations or environments with extremely high humidity. A humidity upper limit should be set, and control should be achieved through a humidity controller. Alternatively, an intelligent environmental control cabinet can be used, integrating heating, dehumidification, ventilation, temperature and humidity sensors, and an intelligent controller. S5. Implementation of the plan: Carry out the construction or renovation of transmission lines in accordance with the differentiated anti-icing and anti-icing plan. During the construction process, special quality supervision shall be carried out on the tower foundations, conductor crimping and insulator string installation in the heavy icing section. S6. Online monitoring and status assessment: Real-time data collection of transmission line operation status, substation operation status, and on-site environmental data through online monitoring devices. The anti-icing status of the line is assessed based on preset thresholds. An early warning is triggered when the real-time ice thickness reaches 80% of the design ice thickness or the insulator leakage current exceeds the threshold. S7. Dynamic maintenance and adjustment: Based on early warning signals and online monitoring data, and combined with the parameters of differentiated design schemes, a maintenance strategy is generated: when the ice thickness is close to the design value, AC short-circuit de-icing is initiated on the lines with reserved de-icing interfaces; When tower tilt exceeds the limit, the foundation is reinforced or windproof guy wires are added; the hydrophobicity of composite insulators and the tightness of hardware bolts are regularly inspected and maintained to form a closed-loop management of "design-implementation-monitoring-maintenance"; S8. Effect Evaluation and Standard Update: The implementation effect of the differentiated design scheme is evaluated annually, and indicators such as ice disaster failure rate and power outage duration are statistically analyzed. Combined with newly accumulated meteorological and fault data, the parameters of the icing zone zoning model and the differentiated design standards are revised to achieve dynamic optimization of the technical scheme.

4. The design and maintenance method for anti-icing and ice-resistant schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: In step S2, the trained random forest machine learning model is applied to every grid cell in the entire region. The model outputs the predicted icing proxy variable value for the cell, thereby generating a continuous icing risk level distribution map. Then, based on the statistical distribution of the predicted values ​​or by setting thresholds in conjunction with engineering experience, the continuous risk index is divided into different icing risk levels, and finally, an icing level distribution map is generated.

5. The design and maintenance method for anti-icing and ice-resistant schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: Random forest machine learning model training: The site data is divided into training set and test set. After training the model with the training set, the prediction accuracy of the model is evaluated with the test set.

6. The design and maintenance method for anti-icing and ice-resistant schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: The icing risk level is divided into low risk, medium risk, high risk and very high risk, and the corresponding recommended ice thickness is ≤5mm for light ice zone, 10mm for medium ice zone, 15mm for heavy ice zone and ≥20mm for super heavy ice zone.

7. The design and maintenance method for anti-icing schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: In step S41, the tower and foundation design also includes using the LCCA model to conduct a full life cycle cost analysis, and determining the optimal tower type based on the full life cycle cost analysis results; The LCCA model is: LCCA = C_i + PV(C_o) + PV(C_f) (PV is the present value) Initial construction cost (C_i), operation and maintenance cost (C_o), failure loss cost (C_f).

8. The design and maintenance method for anti-icing schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: In step S42, the design of the AC short-circuit de-icing interface includes configuring a de-icing switch at the beginning of the line, configuring a three-phase short-circuit disconnector at the end of the line, and a monitoring device for monitoring the de-icing current and voltage.

9. The design and maintenance method for anti-icing schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: In step S3, The Gumbel distribution model has the following distribution function: in, For position parameters, For scale parameters; The steps for calculating ice thickness include: sample extraction, which involves extracting the annual maximum ice thickness sequence from historical winter data of meteorological stations; and parameter estimation, which uses methods such as the method of moments and maximum likelihood to estimate the parameters of the Gumbel distribution. and Design value calculation: for the return period Its corresponding ice thickness It can be obtained from the following formula: Ice load calculation: Assumptions: Assume the ice is a hollow cylinder uniformly covering the conductor, and the weight of ice per unit length is... It can be obtained from the following formula: Design ice thickness (mm) Wire diameter (mm) Ice density (kg / m³) Gravitational acceleration 0.9: Reduction factor considering that the icing is not completely dense. Ice weight ratio It can be obtained from the following formula: The cross-sectional area of ​​the conductor is (mm²). Calculation of icing wind load: The equivalent diameter of the conductor is increased to... The basic wind pressure is determined based on the return period and the regional basic wind pressure map. Wind load per unit length It can be obtained from the following formula: Wind pressure non-uniformity coefficient Wind pressure height variation coefficient The shape factor for icing conductors is typically taken as 1.

2. Wind load adjustment factor The angle between the wind direction and the conductor axis (90° if perpendicular). =1) Basic wind pressure (Pa) Wind load ratio It can be obtained from the following formula: Overall load comparison: Ice-free wind load ratio: Combined load ratio with icing and wind: Ice cover without wind is more important than load: .

10. The design and maintenance method for anti-icing schemes of transmission lines in low-temperature and icy areas according to claim 1, characterized in that: Step S4 also includes simulation verification analysis using professional software. The simulation verification analysis of conductor mechanical properties uses PLS-CADD and SAG10 computer software, the simulation verification analysis of tower and foundation structural strength uses ANSYS and ABAQUS computer software, and the simulation verification analysis of insulator electric field and ice flashover process uses ANSYS Maxwell and COMSOL Multiphysics computer software.

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