Study On Electromagnetic Environment Of EHV/UHV AC-DC Parallel Transmission Lines

With the rapid development of global energy interconnection construction,the construction of EHV/UHV transmission lines in China has also entered a peak of development.Because of the continuous construction of EHV/UHV transmission lines,transmission corridors are becoming increasingly scarce.Especially in the areas with rapid economic development,the shortage of corridors is more serious,and the demand of the construction of AC/DC parallel lines is more urgent.Due to the coupling effect of transmission lines,the electric fields on the surface of the AC and DC are affected,which causes the electromagnetic environment under the parallel line to change,forming the so-called hybrid ion flow field,hybrid audible noise,and hybrid radio interference.In this paper,based on the parallel 500 kV AC and ±800kV DC transmission lines,the calculation methods of the hybrid ion flow field,hybrid audible noise and hybrid radio interference are studied.The main works are as follows:(1)A mesh-free method based on radial basis point interpolation polynomial(RPIM)is used to calculate the hybrid ion flow field with the influence of wind.Then the effects of different wind speeds on the ion flow field is explained.Meanwhile,measurement data is collected to verify the effectiveness of the calculation method.(2)In view of the lack of corresponding evaluation method for the hybrid audible noise in the parallel lines,the calculation model of AC/DC parallel line based on empirical formula method is established.The effectiveness of the model algorithm is verified and corrected by using the measured data.The influence law of AC/DC lines height,DC conductor pole spacing and AC/DC parallel spacing on the distribution of hybrid audible noise is studied.(3)For the case that the hybrid radio interference in the parallel lines lacks the corresponding evaluation method,the calculation model of the radio interference of AC/DC parallel line is established based on the empirical formula method and the excitation function method.The influence law of AC/DC lines height,DC conductor pole spacing and AC/DC parallel spacing on the distribution of hybrid radio interference is studied.