Frost is an important cause of broken towers (poles) of transmission and distribution lines in high mountains in winter. Strengthen and improve the anti-icing ability of transmission and distribution lines to ensure safe, reliable and economic operation, and effectively reduce the accident rate of transmission and distribution lines. It is related to the safety and stable operation of the power grid and the reliability of power supply and use, to the development of society and economy, the economic benefits of power enterprises, and the people to live and work in peace and contentment. Taking into account the ice disaster in Hefeng County of Hubei Province in the spring of 2005 and the actual situation of towers (poles) and disconnections of transmission and distribution lines in recent years, measures to prevent towers (poles) and disconnections of transmission and distribution lines in high mountains Discuss.
Hefeng County is a small mountainous county with 90 high mountains and 10 low mountains. It has a land area of 2885.26 km2, a population of more than 220,000 people, and an average annual temperature of 15°C. It is a severely frozen area.
1. The hazards of freezing to transmission and distribution lines
Frozen is the condensation of freezing rain with strong cold air. The degree of damage to electrical facilities is mainly related to the thickness of the ice layer deposited on the electrical equipment and surrounding trees.
1.1 The hazard caused by freezing directly on the wire
When the ice on the surface of the wire gets thicker, the wire will bear a load of hundreds of kilograms to dozens of tons. At this time, the wire’s own weight and the pulling force generated by the weight of the ice will be transmitted to the tower through the wire, fittings, and insulators, and the tower will pull the tension again. As long as one of the links such as wires, fittings, insulators, towers, cables, cable insulators, and cable fixings cannot withstand the tension, the tower (pole) and disconnection accidents will occur, and the accident will be extended to one Tension section. There have been three incidents of falling towers and broken wires in the Daya section of the 110kV bridge in Hefeng County. It is because the ice accumulates on the wires that are too thick. The weight of the ice accretion in a tensile section reaches more than 50 tons. The main material of the tower or the steel bolts bear The main material can not be broken due to such a large pulling force, or the steel-clad bolts can be broken, causing the entire base iron tower to break and spread to a tensile section.
1.2 The damage caused by freezing and condensation on the trees around the wire
Although the corridors of power transmission and distribution lines have been cleaned in place according to national standards, as Hefeng County is located to the south of the Yangtze River, the warm and humid summer climate makes trees grow vigorously. Most of the transmission lines are surrounded by buckwheat with a height of more than 15m. When the ice accumulation on the buckwheat is too thick, it will fall to the line corridor without any support (because the trees in the line corridor have been felled to form a space where trees are more likely to fall over), the transmission line cannot bear the weight of large trees, ice and snow. It will open a gap in one of the weaker links such as wires, insulators, towers, cables, cable insulators, and cable fixings, forming a large area of inverted towers (poles). The main ice disaster in Hefeng County in spring 2005 It is caused by this reason.
2 Measures to prevent freezing of transmission and distribution lines
For alpine areas with severe cold weather, freezing seriously affects the safe operation of transmission and distribution lines. The hazards caused by freezing have increased maintenance workload, increased business costs, reduced power supply revenue, and effectively avoided and prevented freezing The harm caused to transmission and distribution lines is a topic that enterprises have to pay attention to.
2.1 Improve engineering design standards, and grasp the quality of engineering construction
The design and construction of power transmission lines that cross high mountains and ridges should be quality control: First, the wind speed and icing thickness should be carefully verified, and conservative design should be adopted as much as possible, and the design should be designed according to the severe ice and snow weather that occurs once in 30 years; The second is to use super-reinforced conductors, insulators and fittings to consider strong tensile strength, and towers to choose short, tensile and reinforced types; third, reduce the span, set more tensile sections, and use tensile towers. Minimize the accident area and prevent accident expansion; fourth, pay attention to the quality of conductors, insulators, fittings, towers, and cables to ensure that the stress requirements of the design are met; fifth, pay attention to the construction of the tower foundation and the sag of the conductor strictly according to the design. After the 110kV bridge in Hefeng County was routed through three tower breaks, the climatic conditions of the line were carefully verified and the cause of the accident was analyzed. The accident section was redesigned and modified: the ordinary self-supporting tower was changed to The reinforced corner tensile tower reduces the height of the tower, increases the tensile section, and shortens the distance of the tensile section; increase the tower positions on individual larger spans to reduce the tensile load of the single-base iron tower. After the above treatment, during the ice disaster in spring of 2005, the line section did not have any accidents of falling tower and disconnection, and the effect was obvious.
2.2 Lines are erected to avoid high mountain vents and forest areas
In winter, the ice accumulates in high mountain vents are relatively thicker. Whether it is daily maintenance, line accident rate, or accident repairs, high mountain vents will bring many disadvantages to work; and forest areas will bring about corridor cleaning. Resistance is also more likely to cause a large-area collapsed tower (pole) to break.
2.3 Do a good job in corridor cleaning
Corridor tree barriers are the main factor affecting the safety of electricity supply. Strengthening the corridor cleaning and the clearing of tall trees on both sides of the corridor can effectively prevent freezing weather and large trees from overturning on the wires and towers.
2.4 Strengthen maintenance and governance
Carefully and meticulously do a good job of maintenance and management: such as the adjustment of the cable, the firmness of the bolts of the steel wire, the inspection and replacement of the cable insulator, the adjustment of the wire sag, etc. can avoid the occurrence of part of the collapsed tower (pole) disconnection accident.
Disclaimer: The information comes from the Internet, periodicals, or provided by the author. The content does not represent the views of this website and is for reference only. If there is an infringement of your copyright or other behavior that harms your interests, we will immediately correct it and delete the relevant content.
