Investigation And Analysis On The Electromagnetic Environmental Impact Of Multiplexing Corridor 750 KV High Voltage Transmission Line

In recent years,with the rapid development of China's economy,the construction of power grid is changing with each passing day,followed by the growing shortage of land resources.In order to reduce the impact on local planning,people's lives and natural landscape,the form of multi-circuit HVAC transmission line common corridor has become an inevitable trend.The electromagnetic environment of EHV transmission lines with multiple circuits in the same corridor has become an important issue to be studied.In this paper,the investigation and analysis of electromagnetic environmental impact are carried out for the three-circuit parallel transmission lines of 750 kV Qiaowan-Jiuquan converter station located in Guazhou County,Jiuquan City,Gansu Province.The research results have important guiding significance for the construction of similar transmission lines and the evaluation of electromagnetic environmental impact.According to the engineering example of 750 kV Qiaowan-Jiuquan converter station three-circuit parallel transmission line,the electromagnetic environment of typical high voltage parallel transmission line is monitored by EFA-300 electromagnetic radiation analyzer.The attenuation trend of power frequency electric field and magnetic induction intensity is obtained by correcting and analyzing the monitoring data.By using the two-dimensional theoretical model of power frequency electromagnetic field,the actual tower parameters of the project are selected to predict its electromagnetic field theoretically,and the results are compared with the monitoring data.The results show that the theoretical prediction results are in good agreement with the actual monitoring data,and the theoretical prediction data are conservative,which verifies the reliability and feasibility of the two-dimensional electromagnetic field calculation model.Aiming at the two common types of straight towers in 750 kV transmission lines,which are maximum and minimum spacing,four different parallel arrangement combinations are combined.The electromagnetic environment prediction of multi-circuit UHV transmission lines under parallel conditions is carried out.The results show that the wider the spacing of towers outside the corridor,the wider the corridor;and the higher the tower height,the faster the attenuation of power frequency electromagnetic field,the faster the corridor can pass through.Adjust tower height to save corridor width.However,the increase of tower height may increase the risk of power security.Therefore,it is suggested that the appropriate tower type should be selected according to the corresponding terrain and topography in order to reduce the tower height and save the corridor width.The method of reducing the power frequency electric field of EHV transmission line is studied.Through the theoretical prediction of the influence of four factors on powerfrequency electric field,such as the transverse position of shielding line,the erection height,the number of shielding lines and the distance between lines,the results show that the shielding line can effectively reduce power frequency electric field,which has reference value for similar transmission line construction and electromagnetic environmental impact assessment in the future.