Corona Discharge Problem in Extra High Voltage Transmission Line

Abstract

Despite the great successes made both in our country and abroad, and the existing needs of industry in means and methods of measurement, the electric field of industrial frequency was not covered by methods, and by means of measurement, means of calibration and verification, as well as standards governing measurement techniques. Existing methods and means of measuring electric field strength are not suitable for measuring with satisfactory accuracy the fields of industrial frequency near and on the surface of electrical equipment due to the introduction of significant distortions in the electric field. This suggests the need to provide industry, science, ecology and other aspects of human activity with the necessary knowledge to create tools and methods for measuring the electric field intensity of industrial frequency. As a consequence of the above, the relevance of the topic of the thesis follows from the requirement for the further development of the theory, methods and means of measuring electric field intensity at an industrial frequency, which ensure the reliability and satisfactory accuracy of measurements both near electrical equipment and in the free space of power lines. A significant increase in the power, range and voltage of the lines, which reflects the main trend in the development of electric power transmission technology in recent decades, has put forward a number of new scientific and technical problems and has demanded a more perfect solution to the problems previously considered with respect to lines of lower voltage classes. Such tasks, the solution of which determines to a large extent both the cost of the structure and the economical operation of power lines of three-phase currents of extra high voltage, include the task of engineering methods for calculating various manifestations of the corona on wires. Corona discharge is the phenomenon which occurs on extra high voltage transmission lines. Because of corona there is much loss occurs in the transmission system. We can also identify corona discharge on lines by means of blue color spark and hissing sound. A corona discharge is an electrical discharge. Corona has also a typical sound called hissing sound, by which we can identify corona discharge. Corona discharges generally occur in high voltage transmission system. It is very harmful for transmission system, because as it is loss it losses energy flowing in the system. Corona takes place in a high voltage transmission line when neutral atom or molecule in a strong electric field is ionized. Happening so positive ion and free electron created around the conductor and the conduction takes place through air between conductors of high voltage transmission line. It causes the power loss in line, audible noise, electromagnetic interference, purple glow, and ozone production and insulation damage of the insulating medium.