Method for determining ice thickness of ground wire design of overhead transmission line

Abstract

The application discloses a kind of overhead transmission line ground wire design ice thickness determination method, comprising the following steps: S1, the synchronous icing observation data of same direction, same path, different suspension height of existing long-term icing observation station in region is collected, and the synchronous icing observation data of same direction, same suspension height, different line diameter;S2, the wire icing standard ice thickness of long-term icing observation station different suspension height is calculated;S3, the calculation formula of different standard specification about icing and wire suspension height conversion and its applicable conditions are collected, and the conversion formula of overhead transmission line icing thickness and wire suspension height below 100m is determined comprehensively;S4, the icing standard ice thickness of long-term icing observation station different line diameter wire is calculated;S5, the ground wire icing magnitude corresponding to different design ice area of conductor is calculated;S6, the ground wire design ice thickness in different design ice area of conductor is determined.It is favorable to promote the anti-ice differentiation design capability of overhead transmission line, improve the economy and safety and stability of overhead transmission line.

Description

Technical Field

[0001] This invention relates to the field of power line icing calculation, specifically to a method for determining the design ice thickness of the ground wire of an overhead transmission line. Background Technology

[0002] Domestic and international research indicates that the amount of icing is related to the height of power lines. Near-surface wind speeds generally increase with altitude. During the icing development period, under the same water vapor conditions and within a certain wind speed range, the higher the wind speed, the more water droplets the power lines capture, resulting in a larger amount of icing, generally exhibiting an exponential distribution. Domestic and international research institutions have conducted preliminary studies on the relationship between icing and altitude, but due to limitations in experimental conditions, relatively mature research conclusions have not yet been obtained for a large range of altitudes.

[0003] The relationship between icing and wire diameter is more complex, and scholars both domestically and internationally hold differing views, mainly two: one view holds that icing is related to wire diameter, i.e., the weight of icing increases with increasing wire diameter, while the ice thickness decreases; the other view holds that icing is unrelated to wire diameter. However, research based on measured data indicates that icing is related to wire diameter. Langmuir and Blodgett proposed a theory of the collision efficiency of water droplets carried by steady wind on a vertical, smooth cylinder. This theory posits that ice thickness decreases with increasing cylinder diameter, and that icing will not occur when the cylinder exceeds a certain diameter, which is the critical diameter for icing. Finstad and Lozowski (1988) proposed a formula for calculating the critical diameter based on numerical analysis, but neither proposed a formula for icing with increasing diameter. Summary of the Invention

[0004] To address the aforementioned shortcomings in the existing technology, the present invention provides a method for determining the design ice thickness of the ground wire in overhead transmission lines, which solves the problem of determining the design ice thickness value of the ground wire.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: a method for determining the ice thickness of the ground wire in overhead transmission lines, comprising the following steps:

[0006] S1. Collect synchronous icing observation data from existing long-term icing observation stations in the region, along the same direction and path but at different suspension heights, as well as synchronous icing observation data from the same direction and suspension height but at different wire diameters.

[0007] S2. Calculate the standard ice thickness of power lines at different suspension heights based on synchronous icing observation data at different suspension heights of long-term icing observation stations, and fit the curve of icing variation with power line suspension height according to the average value of the data sample.

[0008] S3. Collect the calculation formulas and applicable conditions for the conversion between icing and power line suspension height in different standards and specifications, and comprehensively determine the conversion formula between icing thickness and power line suspension height for overhead transmission lines below 100m.

[0009] S4. Calculate the standard ice thickness of wires of different diameters at long-term icing observation stations based on synchronous icing observation data of different wire diameters, and determine the conversion formula between icing thickness and wire diameter by fitting the average value of the data samples.

[0010] S5. Based on the selection results of conductors and ground wires and the suspension height in different design ice zones, calculate the ice accumulation level of the ground wire corresponding to different design ice zones of the conductor.

[0011] S6. Compare the differences in the amount of ice covering the conductor and ground wire to determine the design ice thickness of the ground wire in different ice-covered areas of the conductor.

[0012] Further: Step S1 specifically includes:

[0013] S11. Identify long-term stations within the study area that have synchronous icing observations with the same wire diameter, the same direction, and different suspension heights, as well as synchronous icing observations with the same direction, the same suspension height, and different wire diameters.

[0014] S12. Compile information on the direction, suspension height, type, diameter, and ice accumulation anomaly records of power lines observed at long-term stations;

[0015] S13. Select observation data without icing anomalies, and compile synchronous icing observation data with the same wire diameter, the same direction, and different suspension heights, as well as icing observation data with the same direction, the same suspension height, and different wire diameters.

[0016] Furthermore: the ice accumulation anomaly record includes ice removal record and missing measurement record, the suspension height is 2~23m, and the wire models with different diameters include LGJ-970, LGJ-720, LGJ-630, LGJ-400, and LGJ-185.

[0017] Further: Step S2 specifically includes:

[0018] S21. Calculate the standard ice thickness values ​​for synchronous icing observation data at different suspension heights at each long-term station.

[0019] S22. Calculate the overall average value of the standard ice thickness at different suspension heights;

[0020] S23. Fit the curve of icing as a function of power line suspension height based on the overall average value at different suspension heights. The fitting calculation formula is as follows:

[0021]

[0022] In the above formula, Z represents the designed wire suspension height, B represents the designed standard ice thickness for the wire, Z0 represents the actual measured wire suspension height, and B0 represents the actual measured standard ice thickness for the wire. The fitting index is... This is the height conversion factor.

[0023] Further: Step S3 specifically includes:

[0024] S31. Review the calculation formulas for icing and power line suspension height in existing standards and specifications;

[0025] The standards and specifications include QX / T 528-2019, DL / T 5158-2021 / DL / T 5509-2015, СНиП2.01.07-85, ASCE 7-16, IEC 60826-2017, and ISO 12494-2017;

[0026] S32. Based on the overall average value of the standard ice thickness for a suspension height of 10m, apply the height conversion factors in the standards and specifications of CNP 2.01.07-85, ASCE 7-16, IEC 60826-2017, and ISO 12494-2017. Calculate the standard ice thickness for icing in the height range of 2-23m;

[0027] S33. Based on the fitted curve of ice accumulation with the height of the power line suspension, compare the difference between the 2-23m height range and the standard ice thickness calculation value, and select the calculation method of the standard specification that is closest to the curve.

[0028] S34. Based on the overall average value of the measured standard ice thickness at various heights, and using the calculation method of the selected standard specification, fit the ice thickness variation curve with height in the 20~100m range.

[0029] S35. Determine the ice accretion height fitting index for each height range below 100m. We obtained a conversion formula between the icing thickness of overhead transmission lines below 100m and the suspension height of the power lines.

[0030] Further: Step S4 specifically includes:

[0031] S41. Calculate the standard ice thickness value of synchronous icing observation data of different wire diameters at each long-term station.

[0032] S42. Calculate the overall average standard ice thickness for wires of different diameters;

[0033] S43. Fit the curve of icing variation with wire diameter based on the overall average value of different wire diameters. The fitting formula is:

[0034]

[0035] In the above formula, To design the wire diameter, To measure the actual wire diameter, Here, B represents the fit index, B0 represents the standard ice thickness of the designed wire, and B0 represents the measured standard ice thickness of the wire. This is the height conversion factor.

[0036] Further: Step S5 specifically includes:

[0037] S51. Based on the research results of conductor and ground wire selection and tower planning of a certain overhead transmission line, determine the wire diameter and suspension height of conductor and ground wire in different design ice zones, and calculate the difference in suspension height of conductor and ground wire.

[0038] S52. The ground clearance for calculating the design ice thickness of overhead transmission line conductors is 10m. Determine the basic ground clearance for calculating the design ice thickness of ground wires.

[0039] S53. Based on the conversion formula between ice thickness and wire suspension height for overhead transmission lines below 100m, calculate the height conversion factor from the design ice thickness of the conductor to the design ice thickness of the ground wire.

[0040] S54. Based on the curve of icing variation with wire diameter, calculate the wire diameter conversion factor from the design ice zone of the conductor to the design ice thickness of the ground wire.

[0041] S55. Multiply the height conversion factor by the wire diameter conversion factor to obtain the conversion factor for converting the design ice zone of the conductor to the design ice thickness of the ground wire.

[0042] S56. Design ice zones based on conductors of different grades (10mm, 15mm, 20mm, ..., 70mm, 80mm), and calculate the design ice thickness of the ground wire corresponding to the ice zone.

[0043] Further: Step S6 specifically includes:

[0044] S61. Calculate the difference between the design ice thickness of the ground wire and the design ice area of ​​the conductor in the design ice zone of conductors of different grades of 10mm, 15mm, 20mm, ..., 70mm, 80mm respectively.

[0045] S62. The difference between the design ice thickness of the ground wire and the design ice area of ​​the conductor is grouped into an arithmetic sequence of 5mm to obtain the grouped difference level.

[0046] S63. Within the design ice zone of conductors of different grades (10mm, 15mm, 20mm, ..., 70mm, 80mm), the difference grade after merging shall be used as the increase in icing amount required for the ground wire design ice thickness compared to the conductor design ice zone.

[0047] Furthermore: the merging method is as follows:

[0048] When the difference between the designed ice thickness of the local conductor and the designed ice area of ​​the conductor is 5n~5(n+1)mm, the difference level after merging is 5(n+1)mm, where n=0,1,….

[0049] The beneficial effects of this invention are as follows: This invention provides a method for determining the design ice thickness of the ground wire of an overhead transmission line, clarifying the difference between the design ice zone of the conductor and the design ice thickness of the ground wire, and solving the problem of determining the value of the design ice thickness of the ground wire. This invention uses observation data from icing observation stations to obtain a method for determining the design ice thickness of the ground wire in different design ice zones of overhead transmission lines, which is conducive to improving the differentiated design capability of overhead transmission lines against icing and improving the economy and safety stability of overhead transmission lines. Attached Figure Description

[0050] Figure 1 This is a flowchart illustrating a method for determining the ice thickness of the ground wire in an overhead transmission line according to an embodiment of the present invention. Detailed Implementation

[0051] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0052] The specific implementation example is as follows:

[0053] like Figure 1 As shown in the figure, this embodiment proposes a method for determining the design ice thickness of the ground wire of an overhead transmission line, including the following steps:

[0054] Step 1 involves collecting synchronous icing observation data from existing long-term icing observation stations within the area, using the same direction, wire diameter, but different suspension heights, as well as synchronous icing observation data from the same direction, suspension height, but different wire diameters. This includes icing observation direction, observation height, wire type and diameter, icing observation data, and explanations of icing anomaly records (such as ice shedding records, missing measurement records, etc.). This step 1 includes:

[0055] Step 1.1 Based on the icing observation data of XXXXXXXXX Company over the years, a total of 6 long-term icing observation stations in area X carried out synchronous icing observations with the same diameter, the same direction, and different suspension heights. These stations are Station A, Station B, Station C, Station D, Station E, and Station F. The observation period for each station is more than 7 years. The relevant information for each station is shown in the table below.

[0056]

[0057] According to the icing observation data of XXXXXXXXX Company over the years, only Station A has carried out synchronous icing observations in the same direction, at the same suspension height, and with multiple wire diameters. The relevant information is shown in the table below.

[0058]

[0059] Step 1.2 Compile information from long-term station observations, including power line direction, suspension height, power line type, power line diameter, and records of icing anomalies (such as de-icing records and missing measurement records). Synchronous icing observations at different heights primarily include 2m, 5m, 8m, 9m, and 10m, with only Station B having observation heights above 10m, and the maximum observation height being 23m. Synchronous icing observations at different wire diameters involve five power line types: LGJ-970, LGJ-720, LGJ-630, LGJ-400, and LGJ-185.

[0060] Step 1.3 Filter out the observation data without icing anomalies, and compile the synchronous icing observation data of the same wire diameter, same direction, and different suspension height of the 6 long-term stations, as well as the icing observation data of the same direction, same suspension height, and different wire diameter of station A.

[0061] Step 2: Calculate the standard ice thickness of power lines at different suspension heights at long-term icing observation stations, and fit the curve of icing thickness versus power line suspension height based on the average value of the data samples; Step 2 includes:

[0062] Step 2.1 Calculate the standard ice thickness values ​​for synchronous icing observation data at different suspension heights for each long-term station;

[0063] Step 2.2 Calculate the overall average value of the standard ice thickness at different suspension heights;

[0064] Step 2.3 Fit the curve of icing as a function of power line suspension height based on the overall average value of different suspension heights. The fitting calculation formula is as follows:

[0065]

[0066] in: Design the cable suspension height (m); Standard ice thickness (mm) for designing electrical wires; The actual measured height of the power line suspension (m); The measured standard ice thickness (mm) for the wire. This is the fit index.

[0067] From this, the fit index can be obtained. . Within 10m, ; When within 10 to 20 meters .

[0068] Step 3 involves collecting calculation formulas and applicable conditions for the conversion between icing thickness and power line suspension height from different domestic and international standards and specifications, including the calculation base, application height, and applicable area of ​​the formulas. A comprehensive conversion formula for icing thickness and power line suspension height for overhead transmission lines below 100m is then determined. This step 3 includes:

[0069] Step 3.1 A detailed review of existing domestic and international standards and specifications regarding the calculation formulas for icing and power line suspension height is provided. The specific standards and their corresponding calculation formulas are listed in the table below:

[0070]

[0071] Step 3.2 Analysis shows that the index α in QX / T 528 is determined based on observation data from Station B from 1988 to 1995, and the index α in DL / T5158 and DL / T 5509 is determined based on observation data from Station B from 1988 to 1995 and Station C from 2006 to 2010. The applicable height is generally less than 30m. The other standards are applicable to heights of 30 to 100m. Among them, the index α in СНиП 2.01.07 and ASCE 7 are 0.30 and 0.10 respectively, and IEC 60826 and ISO 12494 respectively express the linear and exponential relationships with the wire height.

[0072] Step 3.3 Based on the overall average value of the standard ice thickness at a height of 10m calculated in Step 2.2, apply the height conversion factors compiled in CNP2.01.07-85, ASCE 7-16, IEC 60826-2017, and ISO 12494-2017. Calculate the standard ice thickness for icing in the height range of 2–23 m;

[0073] Step 3.4 Based on the ice cover variation curve fitted in Step 2.3, compare the differences between the standard ice thickness calculation values ​​in the 2-23m height range and the standard ice thickness calculation values ​​of each standard, and select the calculation method of the corresponding standard that is closest to the fitted curve.

[0074] Step 3.5 Combine the overall average value of the measured standard ice thickness at various heights, and apply the selected standard calculation method to fit the ice thickness variation curve with height in the 20-100m range;

[0075] Step 3.6 Determine the icing height variation index for each height range below 100m. This yields a conversion formula for the icing thickness and wire suspension height of overhead transmission lines below 100m. Within 10m, ;when When within 10 to 20 meters ;when Within the range of 20 to 100 meters, .

[0076] Step 4: Calculate the standard ice thickness for wires of different diameters at long-term icing observation stations, and determine the conversion formula between ice thickness and wire diameter by fitting the average value of the data samples; Step 4 includes:

[0077] Step 4.1 Calculate the standard ice thickness values ​​for synchronous icing observation data of different wire diameters at each long-term station;

[0078] Step 4.2 Calculate the overall average value of the standard ice thickness for wires of different diameters;

[0079] Step 4.3 Fit the curve of icing variation with wire diameter based on the overall average value of different wire diameters. The fitting calculation formula is as follows:

[0080]

[0081] in: For designing the wire diameter (m); The actual measured wire diameter (m); .

[0082] Step 5: Based on the conductor and ground wire selection results and suspension height in different design ice zones, calculate the ground wire icing level corresponding to different design ice zones; this step 5 includes:

[0083] Step 5.1 Based on the research results on the selection of conductors and ground wires for a certain UHV overhead transmission line, the conductor and ground wire models and wire diameters for 20mm, 30mm, and 40mm conductors used in icy areas are determined as shown in the table below:

[0084]

[0085] Meanwhile, the maximum difference in the suspension height of conductors and ground wires in different ice zones is 25m;

[0086] Step 5.2 The basic height above the ground for calculating the design ice thickness of overhead transmission line conductors is 10m, and the basic height above the ground for calculating the design ice thickness of ground wires is determined to be 35m.

[0087] Step 5.3 Based on the conversion formula between ice thickness and conductor suspension height for overhead transmission lines below 100m obtained in Step 3.6, calculate the height conversion factor from conductor design ice thickness to ground wire design ice thickness as 1.177.

[0088] Step 5.4 Based on the conversion formula between ice thickness and conductor diameter of overhead transmission lines obtained in Step 4.3, calculate the conductor diameter conversion factors from the design ice thickness of 20mm ice zone and 30mm / 40mm ice zone conductors to the design ice thickness of the ground wire, which are 0.991 and 0.994 respectively.

[0089] Step 5.5 Multiply the height conversion factor by the wire diameter conversion factor to obtain the conversion factors of 1.166 and 1.170 for the design ice thickness of the ground wire for 20mm ice zone and 30mm / 40mm ice zone conductors.

[0090] Step 5.6 When the ice zone of the conductor is designed to be 20mm, 30mm, and 40mm, the corresponding ice thickness of the ground wire is calculated to be 23.3mm, 35.1mm, and 46.8mm, respectively.

[0091] Step 6: Compare the differences in icing levels between conductors and ground wires, and propose a method for determining the design ice thickness of the ground wire in different design ice zones; Step 6 includes:

[0092] Step 6.1 When the designed ice zone of the conductor is 20mm, 30mm, and 40mm, the difference between the designed ice thickness of the ground wire and the designed ice zone of the conductor is 3.3mm, 5.1mm, and 6.8mm, respectively.

[0093] Step 6.2 The difference between the designed ice thickness of the ground wire and the designed ice zone of the conductor is grouped into an arithmetic sequence of 5mm. The specific grouping method is shown in the table below:

[0094]

[0095] Therefore, when the ice zone of the conductor is designed to be 20mm, 30mm, and 40mm, the difference between the designed ice thickness of the ground wire and the designed ice zone of the conductor is taken as 5mm, 10mm, and 10mm after being merged.

[0096] Step 6.3 Within the designed ice zone of 20mm, 30mm, and 40mm for the conductor, the designed ice thickness of the ground wire should be increased by 5mm, 10mm, and 10mm respectively compared to the designed ice zone of the conductor.

Claims

1. A method of determining the ice thickness design for ground wires of overhead power lines, characterized in that The method comprises the following steps: S1, collecting synchronous icing observation data of the same direction, the same line diameter, and different suspension heights of the existing long-term icing observation station in the region, and synchronous icing observation data of the same direction, the same suspension height, and different line diameters; S2, calculating the standard ice thickness of the power line of the long-term icing observation station at different suspension heights according to the synchronous icing observation data of the same direction, the same line diameter, and different suspension heights, and fitting the change curve of the icing with the suspension height of the power line according to the average value of the synchronous icing observation data samples of the same direction, the same line diameter, and different suspension heights; S3, collecting the calculation formula and the applicable conditions of the conversion of the icing and the suspension height of the power line in different standard specifications, and comprehensively determining the conversion formula of the icing thickness and the suspension height of the power line of the overhead transmission line below 100 m; S4, calculating the standard ice thickness of the power line of different line diameters of the long-term icing observation station according to the synchronous icing observation data of the same direction, the same suspension height, and different line diameters, and fitting and determining the conversion formula of the icing thickness and the line diameter of the power line according to the average value of the synchronous icing observation data samples of the same direction, the same suspension height, and different line diameters; S5, calculating the icing level of the ground wire corresponding to the different design icing areas of the conductor according to the selection results of the conductor and the ground wire in different design icing areas and the suspension height; S6, comparing the difference between the icing levels of the conductor and the ground wire, determining the design ice thickness of the ground wire in the different design icing areas of the conductor, merging the difference value in an arithmetic sequence with a difference of 5 mm after the merging, and obtaining the difference value grade after the merging; the merging method is as follows: When the difference value between the design ice thickness of the ground wire and the design icing area of the conductor is 5n~5(n+1) mm, the difference value grade after the merging is 5(n+1) mm, and n=0, 1, …; The step S5 is specifically as follows: S51, determining the line diameter and the suspension height of the conductor and the ground wire in different design icing areas according to the selection research results of the conductor and the ground wire of the overhead transmission line and the tower planning research results, and calculating the difference value of the suspension height of the conductor and the ground wire; S52, determining the basic height from the ground for calculating the design ice thickness of the ground wire when the height from the ground for calculating the design ice thickness of the conductor of the overhead transmission line is 10 m; S53, calculating the height conversion coefficient of the design ice thickness of the conductor converted to the design ice thickness of the ground wire according to the conversion formula of the icing thickness and the suspension height of the power line of the overhead transmission line below 100 m; S54, calculating the line diameter conversion coefficient of the design icing area of the conductor converted to the design ice thickness of the ground wire according to the conversion formula of the icing thickness and the line diameter of the power line; S55, multiplying the height conversion coefficient and the line diameter conversion coefficient to obtain the conversion coefficient of the design icing area of the conductor converted to the design ice thickness of the ground wire; S56, calculating the design ice thickness of the ground wire corresponding to the icing area of 10 mm, 15 mm, 20 mm, …, 70 mm, and 80 mm different grades.

2. The method of claim 1, wherein The step S1 is specifically as follows: S11, determining the long-term icing observation station with synchronous icing observation of the same line diameter, the same direction, and different suspension heights and synchronous icing observation of the same direction, the same suspension height, and different line diameters in the research region; S12, arranging the observation information of the power line direction, the suspension height, the power line type, the power line diameter, and the icing abnormal record of the long-term icing observation station; S13, screening out the observation data without icing abnormal record, and respectively arranging the synchronous icing observation data of the same line diameter, the same direction and different suspension heights and the synchronous icing observation data of the same direction, the same suspension height and different line diameters.

3. The method of claim 2, wherein The icing abnormal record includes a de-icing record and a missing record, the suspension height is 2-23 m, and the wire types of different line diameters include LGJ-970, LGJ-720, LGJ-630, LGJ-400 and LGJ-185.

4. The method of claim 1, wherein The step S6 is specifically: S61, respectively calculating the difference between the ground wire design ice thickness and the wire design ice area in the wire design ice area of different levels of 10 mm, 15 mm, 20 mm, …, 70 mm and 80 mm; S62, merging the difference between the ground wire design ice thickness and the wire design ice area in a difference series of 5 mm to obtain the merged difference level; S63, taking the merged difference level as the icing level that the ground wire design ice thickness should be increased compared with the wire design ice area in the wire design ice area of different levels of 10 mm, 15 mm, 20 mm, …, 70 mm and 80 mm.

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