Accidents on high voltage power lines

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Accidents on high voltage power lines

Rasulov F.

Annotation

Electric transmission lines differ according to the probability of accidents occurring in them according to the voltage class they belong to. Thus, the vast majority of accidents that occur in 10/6kV power transmission lines are caused by leakages in transition insulators of line wires at transformer stations and accidental contact of tree branches with overhead lines. However, in 110kV and higher voltage lines, input isolators are already specially prepared and the insulation reserve is high. The probability of tree branches touching high voltage lines is very low considering t-he height of the poles. On the other hand, high voltage lines usually belong to electric power transmission networks and transmit energy from one destination to another over long distances. The areas through which the power transmission lines from such networks pass are not densely populated areas, but are desert or forest-reserved areas. In those areas, since there are areas where birds protect their nests or gather in mass, there are often phase-to-ground or other phase-to-phase closures. As it can be seen, for the investigation of damage occurring in high-voltage lines, the characteristics of the electrical equipment connected to those lines and the investigation of the areas they pass through are extremely important.

Keywords: towers, input isolators, mounting armatures, partial discharges, leakage current.

Аннотация

Расулов Ф. Аварии на высоковольтных линиях электропередач

Линии электропередачи различаются по вероятности возникновения на них аварий в зависимости от класса напряжения, к которому они относятся.

Так, подавляющее большинство аварий, которые происходят на линиях электропередачи 10/6 кВ, вызваны утечками в переходных изоляторах линейных проводов на трансформаторных подстанциях и случайным касанием ветвей деревьев воздушных линий. Однако на линиях напряжением 110 кВ и выше вводные изоляторы уже специально подготовлены, а запас изоляции высок. Вероятность касания ветвей деревьев высоковольтных линий очень мала, учитывая высоту опор. С другой стороны, высоковольтные линии обычно относятся к сетям электропередачи и передают энергию из одного пункта назначения в другой на большие расстояния.

Районы, через которые проходят линии электропередачи таких сетей, не являются густонаселенными, а представляют собой пустынные или лесные заповедные зоны. В этих районах, поскольку есть районы, где птицы защищают свои гнезда или собираются в массе, часто происходят замыкания фаза-земля или другие межфазные замыкания.

Как видно, для расследования повреждений, возникающих на высоковольтных линиях, чрезвычайно важны характеристики электрооборудования, подключенного к этим линиям, и исследование зон, через которые они проходят.

Ключевые слова: опоры, входные изоляторы, монтажная арматура, частичные разряды, ток утечки.

Introduction

High voltage transmission lines are raised from the power station -where the electricity is generated by step up power transformers and transmit the energy to the destinations from the busbars located in their distribution structures via switching equipment. These structures continue up to the portal abutments of most substations at the destination points. In some cases, they transmit electric energy from the distribution structure of the node substations to other substations through the next high-voltage lines (Figure 1). Damages to said connection points and elements of the lines for various reasons eventually result in the opening of the lines. For this, when talking about the reasons for the opening of those lines, the structures of the mentioned elements and the damages that may occur in them should be classified and classified as the reasons for the opening of the lines 1,2.

Fig. 1. Structure of electrical energy transmission in distribution networks

accident high voltage line power transmission leak insulator tree bird

Practical studies

In order to study the openings in high voltage power transmission lines, it is necessary to look at the measures taken in the direction of accidents and their prevention in existing networks. The first of these, as we mentioned above, is the fact that lines 3passing through non-residential areas cause short-circuiting as a result of birds gathering to build nests or sit on those line supports. To prevent them, it is necessary to install things of different structures and sizes that birds can't touch.

This structure can prevent their accumulation by being installed on the supports of the lines and their traverse. The practical implementation of this structure was carried out on the 110 kV 2nd Masalli overhead line. This line, passing through the Hirkan national reserve, was broke to short-circuited several times during the migration season of birds. As a result, there were certain interruptions in the supply of electricity to consumers. In 2019, were installed on supports in the part of that line that passes through the territory of the national reserve [5]. As a result, line breaks have been reduced to a minimum. Also, the breakings occurring outside the migratory season of birds have decreased significantly.

The results of the inspections concluded that this was due to the fact that the surface of the insulators remained clean. Later, the same method was used in the 220kV 3rd and 6th Masalli overhead lines belonging to Azerenergy. The use of this structure in the sections of high-voltage overhead lines passing through protected areas has practically proven itself to meet both the protection of nature's fauna and the requirement of minimum interruption in electricity supply and reliability from the quality indicators of the electric network. Keeping the surface of the insulators clean has resulted in the minimization of leakage currents and partial discharges in them, which has led to an increase in their service life and an economical boiler 4.

Another reason for openings in high voltage power transmission lines is surface discharges in rain or humid weather as a result of frequent dusting of insulators of lines passing through desert areas. In order to prevent this, the weather conditions are predicted in advance and the lines are opened planning for technical inspection and cleaning. However, since the process requires manpower and time, it is not possible to implement it regularly. As a result, it is inevitable to open the lines due to contamination.

The reason for this is that insulators are made of two widely used materials. So, since both porcelain and glass material are hydrophilic substances, they can attract water and create a water ring. As a result, the dust on the water forms a conductive mixture in the insulator. Under the influence of the electric field, the part of the water channel causes discharge, leakage and eventually short circuit. In the end, that insulator chain becomes useless as a whole. In order to prevent the aforementioned, the surface of the insulators should be covered with a hydrophobic substance, so that it filters water without keeping it on it. Silicon is an example of such materials. Silicone coated glass fibre insulators of different sizes are made according to the ready packaged voltage using silicon coating 5.

Conclusion

The vast majority of openings in high voltage power electric transmission lines are caused by damage to supports. The damages that occur in the supports depend on the areas they pass through, the terrain and the characteristics of the environment. The engineering inspection for the study of openings should be both seasonal in nature and check the dependence on different hours of the day. For this, there should be a journal in which openings in electric transmission lines are specially noted and a chronicle of openings should be made.

Список литературы / References

1. Naumov I.V., Gantulga Erkhembayar and Damdinsuren Gantulga Mongol ULS theocin arhin Garziglia. Shinjlekhukhaan utga zohiolyn bichmel buyu Aman buteel State registration of the computer program of Mongolia 7589 dated 11.03.2016;

2. Kosoukhov F.D. Analysis of indicators of asymmetry and power and voltage losses in rural distribution networks 0,38 kV Methods and means of increasing the reliability of power supply, improving the quality of electricity and reducing its losses in the electric networks of rural areas (Leningrad) 2020, pp. 25-40;

3. Naumov I.V., Ivanov D.A., Podyachikh S.V. and Gantulga D. 2013 Symmetrical device for three phase networks with zero wire (Patent for invention No. 2490768 Registered in the state register of inventions of the Russian Federation on August 20, 2013);

4. Yongxia Li and Yulei Gong. Design of Three Phase Load Unbalance Automatic Regulating System for Low Voltage Power Distribution Grids MATEC Web of Conferences Preprint, 2018.

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