Specifications for climatic feasibility demonstration—Meteorological parameter statistics for anti-icing design of overhead transmission line
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drafter:Sun Xian, Song Lili, Lei Yangna, Zhou Yuehua, Xu Junchang, Wang Binglan, Huang Haohui, He Xiaoai
Drafting unit:Shaanxi Provincial Climate Center, China Meteorological Administration Public Meteorological Service Center, Wuhan Regional Climate Center, Xi'an Public Meteorological Service Center, Guangdong Provincial Meteorological Disaster Prevention Technical
Focal point unit:National Technical Committee on Climate and Climate Change Standardization (SAC/TC 540)
Proposing unit:National Technical Committee on Climate and Climate Change Standardization (SAC/TC 540)
Publishing department:China Meteorological Administration
competent authority:China Meteorological Administration
Some standard content:
ICS07.060
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Meteorological Industry Standard of the People's Republic of China
QX/T528—2019
Specifications for climatic feasibility demonstrationMeteorological parameter statistics for anti-icing design of overhead transmission lines
Specifications for climatic feasibility demonstrationMeteorological parameter statistics for anti-icing design of overhead transmission lines overheadtransmissionline2019-12-26Release
China Meteorological Administration
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2020-04-01Implementation
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Normative reference documents
Terms and definitions
Data collection for ice-resistant design
Temporary icing observation
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Meteorological parameters for ice-resistant design of transmission lines Calculation of ice zone classification
Appendix A (Informative Appendix)
Appendix B (Informative Appendix)
References ·
Correction of standard ice thickness height and line diameter
Correction of ice thickness microtopography during return period
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QX/T528—2019
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This standard was drafted in accordance with the rules given in GB/T1.1—2009. This standard was proposed and managed by the National Technical Committee for Climate and Climate Change Standardization (SAC/TC540). QX/T528—2019
The drafting units of this standard are: Shaanxi Provincial Climate Center, China Meteorological Administration Public Meteorological Service Center, Wuhan Regional Climate Center, Xi'an Public Meteorological Service Center, Guangdong Meteorological Disaster Prevention Technical Service Center. The main drafters of this standard are: Sun Xian, Song Lili, Lei Yangna, Zhou Yuehua, Xu Junchang, Wang Binglan, Huang Haohui, He Xiaoyuan. m
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Climate Feasibility Demonstration Specification
1 Scope
QX/T528—2019
Calculation of meteorological parameters for ice resistance design of overhead transmission lines This standard specifies the calculation method of meteorological parameters for ice resistance design of overhead transmission lines in climate feasibility demonstration. This standard applies to the climate feasibility demonstration of the calculation of meteorological parameters for anti-icing design of overhead transmission lines. 2 Normative references
The following documents are indispensable for the application of this document. For any dated referenced document, only the dated version applies to this document. For any undated referenced document, its latest version (including all amendments) applies to this document. GB/T35235—2017 Ground Meteorological Observation Specification for Wire Icing DL/T5462—2012 Technical Specification for Overhead Transmission Line Icing Observation 3 Terms and Definitions
The following terms and definitions apply to this document. 3.1
overhead transmission line
Overhead transmission line
Power lines with insulators and towers erected on the ground. Note: In this standard, it is referred to as transmission line. 3.2
Glaze
Hard ice layer formed by supercooled liquid precipitation freezing directly after hitting ground objects, transparent or frosted glass, smooth or slightly convex.
Note: Refer to A.14 of Appendix A of GB/T35224-2017.3.3
Milky white ice crystals formed by direct condensation of water vapor in the air or direct freezing of supercooled fog droplets on objects, often in the shape of hairy needles or granules with uneven surfaces, mostly attached to slender objects or the windward side of objects, sometimes with a brittle structure and easy to collapse under shock. Note: Refer to A.15 of Appendix A of GB/T35224-2017.3.4
conductoricing
Conductor icing
Weather phenomenon in which glaze, rime, mixed frozen materials of rain and rime, and wet snow condense on conductors. [Q/GDW11004—2013.Definition 3.1]
Note: In this standard, it is referred to as ice.
Standard ice thickness
standardicethickness
The thickness of ice with different densities and shapes is uniformly converted to the thickness of ice uniformly wrapped around the conductor with a density of 0.9g/cm. [Q/GDW11004—2013, Definition 3.2]
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Return period ice thickness
returnperiod icethickness
The ice thickness obtained by calculating the standard ice thickness according to the return period specified in the line design. 3.7
Icing season
The time from the first icing process in July of the current year to the end of the last icing process in June of the next two years. 3.8
reference meteorological station
National meteorological observation station with long-term meteorological observation data referenced or quoted in meteorological analysis and calculation. Note 1: The long period is generally not less than 30 years.
Note 2: National meteorological observation stations include national benchmark climate stations, national basic meteorological stations and national general meteorological stations defined in GB31221-2014. [QX/T469-2018, definition 3.2]
4 Symbols
The following symbols apply to this document.
A: ice cover cross-sectional area (including conductor), in square millimeters (mm); a: ice cover major diameter (including conductor), in millimeters (mm); B: standard ice thickness of power lines, in millimeters (mm); B.: standard ice thickness, in millimeters (mm); c: ice cover minor diameter (including conductor), in millimeters (mm); G: ice cover weight, in grams (g);
I: ice cover circumference, in millimeters (mm): Ka: micro-topography correction coefficient;
K: height correction coefficient;
K,: ice cover shape coefficient;
K. : Wire diameter correction coefficient;
L: ice-covered body length, in meters (m); R: ice-covered radius (including conductor), in millimeters (mm); r: conductor radius, in millimeters (mm); : Design conductor height from the ground, in meters (m); 2o: Measured or investigated ice attachment height, in meters (m); p: ice density, in grams per cubic centimeter (g/cm*); α: power exponent;
9: Design conductor diameter, in millimeters (mm); o: Measured or investigated ice-covered conductor diameter, in millimeters (mm). 5 Collection of data for anti-icing design
5.1 Meteorological data
5.1.1 Basic data of meteorological stations along the transmission lines: observation years and historical evolution of the stations; geographical information (longitude, latitude, altitude); routine meteorological observations and weather phenomenon data during the icing period (air pressure, temperature, precipitation, relative humidity, wind, snow, fog, sleet, rime). For meteorological stations with records of ice accumulation on power lines, collect all records of ice accumulation on power lines and corresponding hourly values of meteorological elements such as air pressure, temperature, precipitation, relative humidity, wind speed, wind direction, and the start and end dates of the icing process.
5.1.2 Weather data on meteorological disasters along the transmission lines: Investigate and collect data on the transmission lines. Records and reports of various meteorological disasters that may have an impact on the design, such as blizzards, gales, sleet, freezing rain, ice, fog, rime, and rime. 5.2 Icing data
5.2.1 Icing conditions of existing transmission lines and communication lines along the transmission lines, records and reports of ice damage accidents, etc. 5.2.2 Data on icing sites along the transmission lines: geographical and topographical features of icing sites, time of icing occurrence and number of days of icing, etc.; regional distribution of the maximum ice weight along the line
5.2.3 Distribution map of ice areas in the power grid.
5.3 Topographic and geomorphic data
The geographical coordinates and elevation of the transmission line demonstration area and the typical topographic and geomorphic features of the area, such as high mountain watersheds, domain mouths, lakes, reservoirs, rivers, forest ranges and wind ducts. 6 Temporary ice observation
6.1 Observation principles
When one of the following situations occurs in the transmission line demonstration project, short-term ice observation should be carried out along the line to provide a basis for the analysis and design of ice areas of the transmission line:
a) The ice may be serious but the ice situation cannot be obtained through the existing data survey; b)
The line passes through the iced area, and there are many lines passing through, and the ice data cannot meet the design needs; UHV (1000kV AC line or ±1100kV, ±800kV DC line), 750kV and important 500kV lines pass through the iced area.
6.2 Observation content
6.2.1 The observation of continuous icing process and related meteorological elements shall be carried out in accordance with GB/T35235-2017 or DL/T54622012.
During the observation, the icing process should be recorded in full by a camera system or photographed. 6.2.2
6.3 Observation period
The observation time should be no less than one icing period. If the observed icing data is not representative, the observation time should be extended. 7 Calculation of meteorological parameters for ice resistance design of transmission lines 7.1 Calculation of standard ice thickness
7.1.1 Preliminary calculation
Based on the ice accumulation data of transmission lines observed by meteorological observation, the following three calculation methods can be used to calculate the standard ice thickness: a) When there is measured ice weight (G), use formula (1); B, =(G/0.9 yuan L+r).5—1
b) When there is measured ice major diameter (α) and minor diameter (c), use formula (2); YTkAa-cJouaki
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B,=（p/3.6(ac—4r2）)+r)a5-rWhen there is a survey or measured ice radius (R), use formula (3); c
B,=(p/0. 9(K,R2—r2)).s
:(2）
·（3)
The ice density (e) in formula (2) and formula (3) is determined by formula (4) to (6) based on the observed ice data in areas with measured ice data. Formula (4) is used to calculate the ice density based on the measured major diameter (a) and minor diameter (c); Formula (5) is used to calculate the ice density based on the ice perimeter (I); Formula (6) is used to calculate the ice density based on the ice cross-sectional area (A). For areas without measured data, the ice density can be selected with reference to Table 1.
元L(ac-4r）
L(-4元7)
L(A-元r)
Table 1 Density p range of various types of ice cover
Icing type
0.70~0.90
0.10~0.30
In high altitude areas, β should be selected close to the lower limit; in low altitude areas, p should be selected close to the upper limit. Mixed freezing of rain, frost and rime
0.20~0.60
（5）
0.20~0.40
K in formula (3 is determined by calculation and analysis of local measured icing data. For areas without measured data, refer to Table 2 for selection. Table 2 Ice shape coefficient K, range
Ice type
Rain, frost, rime
Mixed freezing of rain, frost and rime
Name of icing attachment
Power line, communication line
Branches, poles
Power line, communication line, branches, poles
For small icing K, select by the lower limit; for large icing K, select by the upper limit. 7.1.2 Correction of height and wire diameter
0.80~0.9 0
0.30~0.70
0.80~0.95
It is necessary to correct the standard ice thickness for height and wire diameter, and uniformly correct it to the ice thickness of a conductor with a diameter of 26.8 mm and a height of 10 m above the ground. The correction formula is shown in formula (7).
Wherein, the coefficients K, K and related to the standard ice thickness are shown in Appendix A. 7.2 Calculation of ice thickness during return period
7.2.1 Preliminary calculation of ice thickness during return period
Preliminary calculation of ice thickness during return period is performed for the following different situations: ...(7)
a) If the ice observation data along the transmission line is long enough (more than 30 years), the probability statistics method can be used to calculate the ice thickness of different return periods according to the probability distribution model. The probability distribution model should adopt the extreme value type I (Gumbel distribution). b) The ice observation data along the transmission line is short, while the ice observation data at the surrounding meteorological stations are long (more than 30 years). We should establish a regression model (empirical statistical model) for the ice thickness along the transmission line and the conductor of the meteorological station, and use the extreme value type I (Gumb el) Calculate ice thickness with different return periods using the distribution. c) The ice observation data along the transmission line and the ice observation data at the surrounding meteorological stations are both short in age. First, a regression model between the ice thickness of the conductors at the meteorological station and the meteorological factors should be established to extend the ice data at the meteorological station for a long time. Then, a regression model between the ice observation data along the transmission line and the extended ice data at the meteorological station should be established. After the ice data is extended for a long time, the extreme value type I (Gumbel) distribution should be used to calculate ice thickness with different return periods. d) The ice observation data along the transmission line is short in age and there is no ice observation data at the surrounding meteorological stations. A regression model (empirical statistical model) between the ice thickness of the conductors and the meteorological factors at the meteorological station should be established. After the ice data is extended for a long time, the extreme value type I (Gumbel) distribution should be used to calculate ice thickness with different return periods. The calculation steps are as follows: 1) According to the ice observation data, select the meteorological observation data such as temperature, relative humidity, wind speed, water vapor pressure and precipitation that are closely related to the wire ice in the area, as well as possible geographical factors (altitude, slope, slope direction, etc.). The relevant meteorological data should be selected from the daily or hourly observation data of the wire ice day and the day before and the day before 2: Use the multivariate stepwise regression method to conduct regression analysis on the wire ice data and high-impact meteorological factors and geographical factors, 2
Establish a regression equation between standard ice thickness and high-impact meteorological factors and geographical factors. The regression equation should pass the significance test to ensure that the equation can converge;
According to the meteorological factor regression equation, use the high-impact meteorological factor data of each year's ice period to calculate the historical ice sequence of the station 3)
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4) For the extended long-term ice data, the probability statistics method is used to calculate the ice thickness of different return periods according to the probability distribution model. e) There is no ice observation data along the transmission line and in the surrounding meteorological stations. The return period ice thickness can be estimated based on the relevant meteorological factors such as snowfall, wet snow, rain and frost days, frost days, snow depth, and ice survey data along the line.
7.2.2 Correction of micro-topography
When the return period ice thickness is applied to other icing locations along the transmission line, the different return period ice thicknesses calculated in 7.2.1 need to be corrected for micro-topography such as altitude, and the return period ice thickness under different altitudes and micro-topography should be calculated. When making altitude corrections, the different return period ice thicknesses calculated in 7.2.1 are used as standard values. Based on the altitude data and ice cover data, an exponential or linear relationship between altitudes is established to calculate the return period ice thickness at different altitudes; when correcting for micro-topography of special terrain, the conversion factor K is determined by analyzing the measured data. The conversion factor for areas without measured data can refer to Appendix B. 8 Classification of ice zones
8.1 Based on the calculated and corrected ice thickness at different return periods, the ice zones are classified according to Table 3. Table 3 Classification of ice zones
Classification of ice zones
Recurrence period ice thickness range
Light ice zone
(5,10]
Medium ice zone
(10.15）
(15,20）
(20,30]
Heavy ice zone
(3040]
More than 50
8.2 Classification of ice zones: The design ice thickness is less than 20mm and the difference is 5mm; the design ice thickness is greater than or equal to 20mm and the difference is 10mm. The similarities and differences of ice cover exist in different regions. In the generalized ice zones of the same level, the ice cover level is basically similar, and try to avoid too fragmented zoning.
8.3 In order to facilitate the generalized design of the line project, the areas with similar altitude, similar geographical environment (topography, slope, vegetation, etc.), consistent line direction, basically equal ice characteristic parameters, and basically the same designed ice thickness in the same climate zone are divided into one ice zone. 8.4 The ice zone level along the line is divided according to the ice zone level. The ice zone distribution map is drawn according to the rules of Q/GDW11004-2013.
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