| In recent years,China's economy has entered a high-speed development stage.Economic development has put forward higher requirements for transmission capacity.Although the large-scale construction of the power grid alleviates the pressure of power supply,leads to the continuous deterioration of the electromagnetic environment around the transmission lines.Due to the public misunderstanding of electromagnetic radiation under high voltage transmission lines,the construction of UHV transmission lines was repeatedly protested by residents near the high voltage lines,which brought a lot of resistance to the UHV transmission project building.Therefore,the influence of the power frequency electromagnetic field of high-voltage transmission lines on the public has become a major concern of domestic scholars.Most of previous researches on the safety assessment of power-frequency electromagnetic environment under UHV transmission lines only based on numerical simulation,and lack of the research on the field measurement.Firstly,this thesis analyzed the developing trend of UHV transmission project,and summarized the international research status of UHV transmission technology.Secondly,this thesis described the application method of low frequency electromagnetic field intensity analyzer(EHP50F),and introduced the principle of electromagnetic field finite element simulation,and detailed the electromagnetic field simulation software COMSOL based on finite element method,and illustrated the electromagnetic environment basic limits of electromagnetic exposure which was established by the Ministry of Environmental Protection of Country and the International non-ionizing radiation Protection Commission respectively.Thirdly,the electromagnetic environment under 110 kV high voltage transmission line and 750 kV ultra high voltage transmission line was measured.Combined with the actual size of the tower and its technology parameters,the electromagnetic environment model of HV and EHV transmission line was used to simulate the spatial electromagnetic field distribution in different conditions,compared the measured data with the numerical simulation results.The reliability of the electromagnetic environment safety assessment method of UHV transmission lines was verifies.The electromagnetic environment measurement and simulation results of 750 kV EHV transmission line were compared with ICNIRP electromagnetic control limit and China's electromagnetic environment control limit,it demonstrate the safety of 750 kV electromagnetic environment.Finally,the measurement process of space electromagnetic environment of 1000 kV UHV transmission line was introduced in detail,and the influence of forest and probe height on the electromagnetic environment of UHV transmission line was analyzed.In this thesis,the electromagnetic field distribution of 1.5 m section below UHV transmission line was studied,and the safety of electromagnetic environment of 1000 kV UHV AC transmission line was further evaluated by comparing measurement and simulation results with the international standard limits of electromagnetic control.The innovation of this thesis is using the low-frequency electromagnetic field intensity analyzer to measure the electromagnetic environment of high-voltage,ultra-high-voltage and ultra-high-voltage AC transmission lines.The distribution rule of electromagnetic field intensity at different heights and the forest influence on the spatial electromagnetic field intensity of transmission line are studied,and the spatial electromagnetic field distribution of 1.5 m cross-section below the transmission line height is quantitatively analyzed.Comparing the results with the international standards,the thesis evaluate the safety of the spatial electromagnetic field under the high voltage transmission line. |
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