An Investigation On Power Frequence Electromagnetic Effect Of High Voltage Transmission Lines

With the development of electric power industry and the expansion of cities and towns, the voltage rank of transmission lines into cities and towns is continuously raised. People are paying increasing attention to the influence of electromagnetic field of such high voltage and ultra-high voltage transmission lines.This paper makes a reaseach on the mathematic model of power-frequence electric field of high voltage transmission lines by means of the Equivalence-charge Method based on image method. By the emulation and analysis with Matlab, a summarization is made on the distribution pattern of power frequence electric field. At the same time, the effect of lighting wire is also analyzed.Taking the sag of overhead lines into consideration, the paper bases the mathematic model on funicular curve model. Then the distribution pattern of electric field is studied, which is based on such mathematic model. The electric field based on such mathematic model is three-diemensional.After that, the paper makes a reaseach on the mathematic model of power frequence magnetic field of high voltage transmission lines by means of Ampere circuital theorem, and the distribution pattern of power frequence magnetic field is summarized. Taking the sag of overhead lines into consideration, the paper bases the mathematic model on funicular curve model, as well as the Biot Savart law of power frequence magnetic field. The magnetic field based on such mathematic model is also three-diemensional.By emulation and analysis combined with the environmental evaluation standard, some factors affecting the power frequence electric field and magnetic field are analyzed at the same time, such as conduction wire arrangment, height, different phase, double power supply circuit on a single pole, case of slant ground, and shield lines. The paper studies on the measures, which should be taken to impair the power frequence electric field.Emulation software of power frequence electromagnetic field of transmission lines is developped with Visual C and Matlab.