Annotation content. The dissertation is devoted to solving the actual scientific and applied problem in the lightning protection of transmission lines with protected wires of middle classes of voltage from direct lightning strikes.
The urgency of the topic of the dissertation work is that in recent years there has been a significant increase in storm activity on the planet. This leads to a more frequent defeat of electric power facilities, in particular transmission lines (TL). In industrially developed countries, protected wires (TLP) are widely used on medium-voltage lines of 6 - 69 kV voltages, but there are also TL with bare wires.
With the onset of massive use of distribution lines with protected wires, it became necessary to adopt mandatory technical measures for their lightning protection.
The peculiarity of the problem of lightning protection is the fact that, in the absence of special measures, during a thunderstorm overlap of a line insulator, accompanied by a breakdown of solid insulation of the wire, the arc of the industrial frequency, which is formed with high probability, is not able to move along the wire (as with bare wires) and burns in place of isolation breakdown until the line is switched off. This can lead to damage to the insulation of the wire, damage to the insulator of the line and to the wiring of the wire, which is confirmed by the experience of operating lines with protected wires. Since on the line with uninsulated wires the arc under the influence of electrodynamic forces is able to move one of its ends along the wire, the damage factor of the wire due to the thermal effect of the arc was insignificant and did not affect the formation of the concept of lightning protection of the transmission lines. In this case, the prevention of overheating of wire leads to the main reason, which determines the necessity of mandatory use of certain lightning protection measures.
The purpose and tasks of the study. The purpose of the study is to increase the reliability of the protection of the transmission lines of middle classes of voltage with protected wires based on the consideration of the specified values of the number of defeat by direct lightning strikes.
To achieve the goal, the research objectives are defined:
- to analyze the basic methods and means of protection of transmission lines from direct lightning strikes in Ukraine and in the world;
- to determine the main parameters influencing the lightning strikes of the middle classes of voltage lines and to develop the principles of modeling the impression process on large-scale models;
- Develop a plan for a full- factored experiment to investigate the direct damage of lightning strikes with protected and bare wires;
- to conduct experimental studies of damage by direct lightning strikes of overhead lines with protected and bare wires;
- on the basis of the results of experimental studies, to clarify the method of calculating the number of damage of overhead lines by direct lightning strikes;
- Develop new and improve existing methods and means of increasing the safety of the overhead lines with protected wires.
The object of research is the process of losing power transmission lines with protected and bare wires with direct lightning strikes.
Subject of research - electrical and structural parameters of the transmission line with protected wires, affecting lightning damage.
Scientific novelty:
1) The method of object modeling is improved, which differs from the existing ones because the simulation factor is calculated using the lightning orientation height.
2) The method of calculating the number of direct lightning strikes for the determination of the lightning resistance of the air lines of the middle classes of voltage, which differs taking into account the design of the used wires, has been further developed, which allows to improve the accuracy of the calculations.
3) A mathematical model for calculating the number of direct lightning strikes has been further developed, which is characterized by the fact that its parameters are determined on the basis of a method of non-precise logic, which makes it possible to take into account the variational component of the output data.
4) For the first time the method of lightning protection of protected air lines has been proposed, which differs in that it uses phase wires to protect against direct damage, which allows to significantly reduce the damage of protected wires.
Practical value:
The practical value of the work lies in the fact that based on the performed researches, ways of increasing the efficiency of operation of electric netw
