Safety Assessment Of Electromagnetic Environment Of UHV DC Transmission Lines

At present,the economy and society of our country are in a stable and rapid development period,for energy demand is increasing,UHV transmission engineering technology in this critical period plays a very important role,not only optimizes the allocation of resources,but also solve the energy imbalance issues and for our country to implement sustainable development strategy to provide a solid backing.However,the UHV transmission voltage is increasing with the development of the demand.The electromagnetic environment around the transmission line is also not increasingly neglected.In this paper,the electromagnetic field around the UHVDC transmission line was analyzed in detail and the safety assessment was made.Including: DC electric field,ion current density,DC magnetic field.(1)The characteristics of the nominal electric field distribution under the DC tran smission line were analyzed.The method of calculating the nominal electric field and the calculation method of the converted conductor to the equivalent conductor were int roduced respectively.The distribution of the ground under different parameters of the wire structure were calculated.Finally,the distribution of the DC magnetic field was calculated and analyzed.(2)Firstly,the methods and steps of calculating the ion flow field were introduced.Secondly,the finite element software was validated.Finally,the distribution of the electric field and the ion current density under different parameters of the wire structure was analyzed.(3)The safety assessment of human electromagnetic exposure was carried out on UHV DC transmission lines.Firstly,the calculation model of three-dimensional ion flow field was introduced,Then,according to the electromagnetic properties and physiological structure of human tissue,Dielectric constant,based on the establishment of a simplified model in the COMSOL.Finally,the distribution characteristics of the field strength,the human body and the head tissue under the UHV transmission line were analyzed,and the results were compared with the existing conclusions and the existing ICNIRP safety standard.The results showed: as the ± 1100 kV transmission line was under construction,it could only be predictive simulation,I set the wire in the simulation process from the ground height of 28 m,the simulation results found that when the wind speed of 0m/s,the maximum internal electric field was 5.59V/m,had exceeded the general public limit of 0.4V/m and professional limit of 0.8V/m,but the maximum electric field value in the brain was 0.124V/m within two limits,for long-term living in UHV DC transmission lines around the residents will have a certain health risk,so in the actual construction to take a certain reduction in electromagnetic exposure protection measures or to avoid crossing the residential area.