Study On Electromagnetic Transient Characteristics Of UHV Half-wavelength Transmission Technology

The reverse distribution of energy resources and load centers is very obvious at home and around the world.How to realize long-distance and large-capacity transmission and effectively use the energy resources of the Earth’s Arctic wind energy and equatorial solar energy has become the focus of attention.Half-wavelength transmission technology has unique advantages in ultra-long-distance transmission.Although some valuable scientific research achievements have been made in the study of electromagnetic transient of half-wavelength transmission technology,it is still not feasible in engineering and needs further exploration.Based on the theory of multi-conductor transmission line,the unit length parameters of UHV half-wavelength transmission line are analyzed and calculated,and the system simulation model is established by using simulation software PSCAD/EMTDC.Aiming at the problem of latent power supply current of UHV half-wavelength transmission line,the formation mechanism of latent power supply current is analyzed theoretically,and the distribution law and influencing factors of latent power supply current after grounding fault on half-wavelength transmission line are simulated and analyzed.Verify the suppression effect of high-speed grounding switch along the line on the secondary supply current and recovery voltage.The distribution characteristics of voltage and current along UHV half-wavelength transmission lines are studied when the system is running steadily.For the overvoltage problem of UHV half-wavelength AC transmission lines,the generation mechanism and distribution characteristics of line overvoltage under different working conditions or different fault conditions are analyzed.The characteristics of fault overvoltage waveform are compared and analyzed,and the distribution law of line overvoltage is obtained.The suppression measures of overvoltage under different working conditions or different fault conditions are studied,and the suppression effect of lightning arrester installed along the line is verified by simulation.It is concluded that the way of installing lightning arrester along the line combined with quick grounding at the midpoint of the line can reduce the energy consumption of lightning arrester.In this paper,the electric distance compensation technology of UHV half-wavelength AC transmission is studied.In view of the fact that the transmission length of the line exceeds half a wavelength,two methods of compensating the line are proposed,namely,?-type and T-type,and the calculation method of compensation network parameters is analyzed theoretically.It is verified that the electric distance compensation network can make the transmission line with transmission length exceeding half wavelength have half wavelength transmission characteristics.The electromagnetic transient characteristics of the system after electric distance compensation under different working conditions or different fault conditions are simulated and analyzed.The characteristics and distribution law of fault overvoltage waveform are compared and analyzed.This paper studies the suppression measures of system line overvoltage after electric distance compensation under different working conditions or different fault conditions,and verifies the suppression effect of lightning arrester on overvoltage.