Transmission line stress directly affects the tower sag force structure and a safe distance from the safe operation of the transmission lines play a crucial role. Calculation method for the preparation of the design process were complied, simply enter transmission liner parameters can be automatically obtained stress and sag. According to a 500 kV transmission line tests carried out stress sag design verification, checking ground found stress design errors and were corrected to ensure the safety of the project. Calculation program can be developed for different voltage levels for line stress on cables sag design verification

Guo-Sheng Xie

Ke-Jian Ouyang

English

Vibroengineering PROCEDIA

  © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. SEP 2015, VOLUME 5. ISSN 2345-0533 575 
Design verification of stress and sag for 500 kV 
transmission line 
Guo-Sheng Xie1, Ke-Jian Ouyang2 
State Grid Hunan Electric Power Corporation Research Institute, Changsha 410007, China 
2Corresponding author 
E-mail: 1heptri2791@163.com, 2ouykj@126.com 
(Accepted 31 August 2015) 
Abstract. Transmission line stress directly affects the tower sag force structure and a safe distance 
from the safe operation of the transmission lines play a crucial role. Calculation method for the 
preparation of the design process were complied, simply enter transmission liner parameters can 
be automatically obtained stress and sag. According to a 500 kV transmission line tests carried 
out stress sag design verification, checking ground found stress design errors and were corrected 
to ensure the safety of the project. Calculation program can be developed for different voltage 
levels for line stress on cables sag design verification. 
Keywords: 500 kV transmission line, stress and sag, calculation program, design verification of 
stress. 
1. Pay-off stress sag calculation code requirements 
In the design of wire pay-off stress sag, we should first select meteorological conditions and 
safety coefficient calculation. Under normal circumstances, analyzing from the Angle of 
engineering design, there are four kinds of meteorological conditions as control [5], (1) Lowest 
ambient temperature, no wind, no ice. (2) Has the largest wind speed and air temperature, no ice. 
(3) Ice coating, air temperature is –5 Celsius degree, corresponding wind speed. (4) According to 
the annual mean temperature in the local, thinking vibration may occur. Under the condition of no 
ice and no wind, wire stress calculated at 25 % of wire breaking stress. 
In DL/T5092 rules [6], the maximum stress of wire is in the sag lows, Based on safety factor 
ܭ divide the destruction stress of the wire, maximum use stress can have to get. Use the formula 
is expressed as: 
ߪ௠௔௫ =
ߪ௣
ܭ , (1)
where ߪ௠௔௫  – wire’s stress in the sag, low maximum; ߪ௣  – conductor or ground wire of the 
instantaneous failure stress; ܭ – safety factor of guide wire and ground wire. 
Meanwhile, DL/T5092 regulations, Conductor design safety coefficient should not be less than 
2.5, Ground safety factor should be greater than the wire. When a vibration control measures be 
carry out, average running stress of ground should not exceed 25 % of the failure stress. 
2. Pay-off stress sag calculation 
From a certain state of wire stress to ascertain wire stress under an unknown one, fundamental 
principles is based on which the relationship of Two states between the length of wire under the 
stress of the corresponding relationship. When the distance between the wire suspension point is 
fixed, we can get the conductor stress of another state by the principle of same lines if calculate 
the two geometric line length under different meteorological conditions. The equation of the state 
of the wire is presented by: 
ߪ௖ଶ −
ܧݎଶଶ݈ଶ
24ߪ௖ଶଶ = ߪ௖ଵ −
ܧݎଶଶ݈ଶ
24ߪ௖ଵଶ − ܽܧ
ሺݐଶ − ݐଵሻ, (2)
DESIGN VERIFICATION OF STRESS AND SAG FOR 500 KV TRANSMISSION LINE.  
GUO-SHENG XIE, KE-JIAN OUYANG 
576 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. SEP 2015, VOLUME 5. ISSN 2345-0533  
when 1, 2, ..., ܰ stress limit conditions are known, the corresponding parameters are ߛ௠௫, ݐ௠௫, 
ߪ௠௫. Put them into state equation respectively, equation (2) can be written to: 
ߪ௫ଶ ቊߪ௫ + ቈቆ
ܧݎ௠௫ଶ ݈ଶ
24ߪ௠௫ଶ − ߪ௠௫ − ܽܧݐ௠௫ቇ + ܽܧݐ቉ቋ =
ܧݎଶ݈ଶ
24 . (3)
We can know from the second equation, wire pay-off stress calculation under different span first 
need to obtain the known conditions, the known conditions known as the “control condition”. 
If the coefficient in the third equation: 
ܨ௠௫ =
ܧݎ௠௫ଶ ݈ଶ
24ߪ௠௫ଶ − ߪ௠௫ − ܽܧݐ௠௫. (4)
The biggest of the ܨ௠ is the control stress condition. So just put the span of the equation as the 
variable, by comparing the ܨ௠ value to select the control conditions of the qualification and the 
critical span effectively, according to second equation, controlling load, temperature and weather 
conditions allowable stress as the known data. With meteorological condition of wire stress than 
load, temperature data as another kind of meteorological conditions into state equation, can be 
various and stress state of wire.  
If we mark ܽ = ቂቀா௥೘ೣమ ௟మଶସఙ೘ೣమ − ߪ௠௫ − ܽܧݐ௠௫ቁ + ܽܧݐቃ and ܾ =
ா௥మ௟మ
ଶସ , the third equation can be 
written as the following three degree univariate polynomial equation. 
ߪ௫ଶሺߪ௫ + ܽሻ = ܾ. (5)
Equation (5) can be solved by numerical method and satisfactory results can be obtained. After 
the pay-off stress is calculated, we can acquire sag by the following equation: 
݂ = ݈݃
ଶ
8ߪ଴ cos ߮, (6)
where ߮ in the sixth equation is the angle of elevation difference of suspension point. 
3. Developing the check calculation program 
Through related standard procedures [6-7], we can check it for calculating the physical 
properties parameters of wire. 
By entering the largest ice thickness, wind speed design program can automatically acquire 
the uneven shape coefficient and wind pressure coefficients of the wire. According the 
conventional wire stress value to Input horizontal stress initial value of the wire, program can be 
calculate the pay-off stress and sag of the wire. On the basis of getting optic fiber fly strain, we 
can calculate pay-off stress value range by safety factor, then discriminating the right and wrong 
of results. Check calculation program output pay-off stress and sag automatically with a picture. 
The specific processes as shown in Fig. 1. 
4. Design check calculation of engineering cases 
4.1. Project Summary 
In accordance with the relevant standards and the reference information, A 500 kV test circuit 
design wind for 27 m/s, designing ice thickness is 50 mm, guide and ground wire parameters 
shown in the following table. Transmission line tension segment show in Fig. 2. 
DESIGN VERIFICATION OF STRESS AND SAG FOR 500 KV TRANSMISSION LINE.  
GUO-SHENG XIE, KE-JIAN OUYANG 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. SEP 2015, VOLUME 5. ISSN 2345-0533 577 
Table 1. Wire parameters 
Name Mark OD (mm) 
Section 
(mm2) 
Unit 
weight 
(kg/km) 
Ex 
(MPa) 
Coefficient 
of linear 
expansion 
(10-6/°C) 
Failure 
stress 
(N) 
Safety 
factor 
Guide 
line 
JLHA1/G1A-
460/60 29.8 525 1754.9 69000 19.3 393.2 3 
Ground 
wire XGJ-180 17.5 182.8 1521.7 185000 11.5 1230.9 3.85 
4.2. Checking calculation results 
Design check value and error value of ground wire (XGJ-180) compare as Table 2. Due to 
space limitations, this article only gives five typical span and the corresponding four pay-off stress 
temperature value. Correct pay-off stress at different temperature, different representative shift 
away from the stress value at about 45 MPa. The temperature of 5 degrees Celsius represent that 
when span is 350 m, stress value of pay-off is 45.03 MPa and corresponding sag is 4.286 m. 
Design institute of the given ground wire pay-off stress in the table corresponding to pay-off stress 
value under the condition is only 5.22 MPa and The corresponding sag value is 36.975 m. 
Contrastive analysis them, we can conclude that design pay-off stress sag is error. Pay-off stress 
of guide line (JLHA1/G1A-460/60) at different temperature, different representative shift away 
from the stress value at about 18 MPa. The temperature of -5 degrees Celsius represent that when 
span is 350 m, stress value of pay-off is 18.22 MPa. Wire pay-off stress design value and checking 
calculation results are unanimous. 
Table 2. Ground wire pay-off stress design check value and error value contrast 
T(°C) Stress Span 300 325 350 375 400 
15°C Check calculation values 45.49 45.14 44.88 44.66 44.49 Error design value 5.31 5.25 5.20 5.16 5.13 
10°C Check calculation values 45.59 45.23 44.95 44.73 44.55 Error design value 5.33 5.26 5.21 5.17 5.14 
5°C Check calculation values 45.70 45.32 45.03 44.79 44.61 Error design value 5.35 5.28 5.22 5.18 5.15 
0°C Check calculation values 45.81 45.41 45.10 44.86 44.66 Error design value 5.37 5.29 5.24 5.19 5.16 
5. Conclusion 
Developed transmission line pay-off stress sag design checking program, and to conduct a 
500 kV test circuit guide ground wire pay-off stress sag design checking. 
Ground wire type XGJ-180 pay-off table data for calculating is error. Given the pay-off stress 
value only have 5.22 MPa under the condition of 350 m span in temperature 5°C, and the 
corresponding correct value should be 45.03 MPa. Comparison and analysis to determine that it 
will eventually lead to pay-off sag of construction is error, if use error pay-off stress value. To 
ensure the engineering safety and complete successfully, the designer are required to redesign 
drawing. 
References 
[1] Ou Yang-Ke, Hu Botao, Chen Junjun Ultra high voltage wire break line impact study. China Power, 
Vol. 46, Issue 7, 2013, p. 53-57. 
[2] Ou Yang-Ke, Liu Chu, Chen Hongdong 500 kV transmission line path wire fracture cause analysis. 
Electric Power Construction, Vol. 11, 2012, p. 74-78. 
DESIGN VERIFICATION OF STRESS AND SAG FOR 500 KV TRANSMISSION LINE.  
GUO-SHENG XIE, KE-JIAN OUYANG 
578 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. SEP 2015, VOLUME 5. ISSN 2345-0533  
[3] Shao Tianxiao Wire and Mechanical Calculation of Overhead Transmission Lines. China Electric 
Power Press, Beijing, 2003. 
[4] Wei Kong, Dai Xiao-Guang, Yang Zhen-Wei Overhead lines stress sag curve of Matlab. China 
Power, Vol. 42, Issue 7, 2009, p. 46-49. 
[5] Zhang Diansheng Electrical Engineering High Voltage Transmission Lines Design Manual. China 
Electric Power Press, Beijing, 2002. 
[6] 110~220 kV and Above Overhead Transmission Line Design Technical Regulation, DL/T5092-1999. 
[7] Overhead Conductor with Galvanized Steel Wire, GB 3428-2012. 


Design verification of stress and sag for 500 kV transmission line

https://www.jvejournals.com/article/16334/pdf

Design verification of stress and sag for 500 kV transmission line

Abstract

Similar works

Full text

Available Versions

Vibroengineering PROCEDIA