Discussion on anti-freezing of transmission and distribution lines
Discussion on anti-freezing of transmission and distribution lines
Freezing is causing the winter transmission and distribution lines in high mountain areas to collapse (Rod)
The important reason for disconnection is to strengthen and improve the anti-freezing ability of power transmission and distribution lines, to ensure safe, reliable and economical operation, and to effectively reduce the accident rate of power transmission and distribution lines, which is related to the safe and stable operation of power grid and the reliability of power supply and consumption, it is related to the development of social economy, the economic benefits of electric power enterprises and the people's living and working in peace and contentment.
Combined with the ice disaster in the spring of 2005 in Hefeng county, Hubei province, and the collapse of power transmission and distribution lines in recent years (Rod)
, The actual situation of disconnection, on the high mountain area to prevent transmission and distribution lines from falling Tower (Rod), The measures of disconnection are discussed.
Hefeng County is a small mountainous county with 90 high mountains and only 10 low mountains, with a land area of 2885 square meters.
26km2, with a population of more than 220,000 and an annual average temperature of 15℃, is a serious frozen area.
1 damage of freezing to power transmission and distribution lines freezing is condensed by freezing rain and strong cold air. The damage to power facilities is mainly related to the thickness of ice deposited on the surface of electrical equipment and surrounding trees. 1.
1 The harm caused by freezing directly condensed on the wire, when the ice on the surface of the wire becomes thicker and thicker, the wire will bear hundreds of kilograms to dozens of tons of load, at this time, the dead weight of the wire and the pulling force generated by the icing weight will be transmitted to the tower through the wire, hardware and insulator, and the tower will transmit the pulling force to the cable, as long as one of the links such as wires, fittings, insulators, towers, cables, cable insulators and cable fixing parts cannot withstand the tensile force, there will be a tower collapse (Rod)
And the disconnection accident, and expand the accident to a tension section.
There have been three times of tower breaking accidents in Daya section of 110kV Bridge route in Hefeng county, because the ice on the conductor is too thick, and the ice weight of a tension-resistant section has reached more than 50 t, the main material of the Iron Tower or the steel bolt cannot bear such a large tensile force, and the main material is broken, or the steel bolt is broken, which causes the whole base Iron Tower to break and affect a tension section. 1.
2 although the corridors of the power transmission and distribution lines that are harmful caused by freezing condensation on the trees around the wires are cleaned up according to the national standards, Hefeng County is located in the south of the Yangtze River, and the warm and humid climate in summer makes the trees grow vigorously, most of the four sides of the transmission line are buckwheat wood up to 15m or more. When the ice on the buckwheat wood is too thick, it will fall to the line corridor without any support (
As the trees in the line corridor are cut down, a space where trees are easier to overturn is formed)
The transmission line can't bear the heavy pressure of big trees and ice and snow, and the gap will be opened on one of the weak links such as wires, insulators, towers, cables, cable insulators, cable fixing parts, etc, finally form a large area of inverted Tower (Rod)
Broken Line, Hefeng county in the spring of 2005 ice disaster is mainly caused by this reason.
2 anti-freezing measures for power transmission and distribution lines. For high mountain areas with severe weather, freezing seriously affects the safe operation of power transmission and distribution lines. The harm caused by freezing increases the maintenance workload, it increases the cost of enterprises, reduces the income of power supply, and effectively avoids and prevents the harm caused by freezing to power transmission and distribution lines, which is a topic that enterprises have to pay attention. 2.
1 improve the engineering design standard, pay special attention to the engineering construction quality, and control the design and construction of the transmission lines across the high mountains: first, the wind speed and ice thickness should be carefully verified, try to adopt conservative design, at least according to the strong ice and snow weather that occurs once in 30 years;
Second, the wire should adopt the super-reinforced type, the insulator and hardware should consider the strong tension, and the iron tower should choose the short and tensile and reinforced type;
The third is to reduce the gear distance, set up more tension-resistant sections, and use more tension-resistant towers to minimize the accident area and prevent accidents from expanding;
Fourth, pay attention to the quality of wires, insulators, fittings, towers and cables to ensure that the design stress requirements are met;
The fifth is to pay attention to the pouring of the tower Foundation and the SAG of the conductor. The construction should be strictly in accordance with the design.
After the 110kV Bridge route in Hefeng county was broken by three inverted towers, the climate of the line was carefully verified and the cause of the accident was analyzed, and the accident section was redesigned and reformed: change the ordinary self-supporting tower into a reinforced corner tension tower, reduce the height of the tower, increase the tension section and shorten the distance of the tension section;
Increase the tower position on the individual larger span to reduce the tension load of the single base tower.
After the above treatment, in the spring ice disaster of 2005, there was no accident of breaking the tower in this line segment, and the effect was obvious. 2.
2 The line is erected to avoid the mountain vents and forest areas in winter. The ice accumulation in the mountain vents is relatively much thicker, whether it is daily maintenance, line accident rate, or accident repair, the high mountain tuyere will bring many disadvantages to the work;
The forest area will bring more resistance to the corridor cleaning, and it is also easier to cause a large area of the tower (Rod)Disconnected. 2.
3 do a good job in corridor cleaning corridor tree barrier is the main factor affecting safe power supply and use, strengthen the corridor cleaning and the clearing of tall trees on both sides of the corridor, can effectively prevent freezing weather, the big tree overlaid the wires and towers. 2.
4 strengthen maintenance and management, carefully and carefully do a good job of maintenance and management: such as the adjustment of the cable, the firmness of the steel wire Bolt, the inspection and replacement of the cable insulator, the adjustment of the wire sag, etc. can avoid partial tower collapse (Rod)The occurrence of disconnection accidents.