Research On Electromagnetic Environment Of Power Frequency EHV And UHV Transmission Lines

Nowadays, the power system structure of our country cannot supply enough power for our country's economic development, and the distribution of energy resource and load determine that we have to construct long distance, great capability UHV transmission line. With the global economic development and people's increasing environment awareness, the electromagnetic environmental problem caused by power transmission is paid more and more attention. At the same time, as the voltage rating turn into UHV level, electromagnetic environment has become the critical factor which determines the power transmission line's structure and the constructing cost. This paper focuses on the electromagnetic environmental problem of AC EHV and UHV transmission lines.The electromagnetic parameter of power transmission include: power frequency electrical field, power frequency magnetic field, radio inference (RI) and audible noise (AN). With Canadian SES's CDEGS software, this paper makes detail simulation research on the four electromagnetic parameter of AC EHV and UHV transmission line. This paper introduces theoretical calculation method, main affected factor, mitigation technology and their standards for each electromagnetic environment parameter, and the ecology effect of the power frequency electromagnetic field is also discussed. This paper emphasizes on the mitigation method of the power frequency electromagnetic field of UHV transmission line, and put forward that installing shield wires or lower voltage transmission lines under the phase lines to reduce the power frequency electromagnetic field of UHV transmission line, and then make the simulation of it. The result of simulation shows that, installing several shield wires under the phase lines can obviously reduce the power frequency electromagnetic filed of transmission line. And installing lower voltage transmission lines, such as 220kV lines, beneath the phase lines can also reduce the power frequency electromagnetic filed greatly, and it is even better than the first one, this method can save the transmission corridor and land resource.As to the radio inference (RI) and audible noise (AN) of UHV transmission lines, the experimental results done at home and abroad show that the level of RI and AN is comparable with that of EHV. The number of split conductors and the section ofsubconductor have a influence on the RI and AN of UHV transmission line, and increasing the number of subconductors and select larger section conductor can both reduce the level of RI and AN.