Calculation And Distribution Characteristics Of Hybrid Electric Field For AC And DC Transmission Lines On The Same Tower

With the increasing scale of power grid construction,transmission lines are increasingly dense,and transmission corridors are becoming more and more scarce.However,it is an important factor to consider the feasibility of AC and DC transmission tower design in the same stage.Based on this,the distribution characteristics of mixed electric field of AC and DC transmission lines on the same tower are studied and analyzed.By improving the local weak meshless method and applying it to the solution of mixed electric field,the prediction and analysis of mixed electric field on the same tower are achieved.Finally,the distribution characteristics of mixed electric field on the same tower on the ground under the influence of traverse structure and meteorological factors are analyzed.The main work is as follows:(1)An improved local vulnerable meshless method for solving hybrid electric fields is presented.The influence domain and shape function construction methods of conventional local vulnerable meshless method are analyzed,and the system matrix construction process based on moving least squares function is deduced.Then,it innovatively puts forward three ways to construct multiple influence domains,construct the radial basis function to construct the radial basis point interpolation function,and simplify the discrete control equation,which improves the conventional local weak meshless method in three respects.Finally,the case results are compared with the conventional local weak meshless method and the finite element method,which shows the effectiveness and superiority of the improved meshless method in solving electric field problems.(2)The calculation model of hybrid electric field for AC and DC transmission lines with the same tower is established.The influence of AC lines on the distribution of space electric field and space electric potential of DC lines is analyzed.Based on the simulation results,a calculation method of hybrid electric field is presented,which combines mirror method with improved meshless method for local vulnerability.The results obtained by this method are compared with the measured data to verify the accuracy of the mirror method in solving the AC component.At the same time,the improved local vulnerable meshless method based on multiple influence regions is applied to the DC component calculation.The comparison between the measured data and the simulation verifies that the algorithm is suitable for solving the DC component.(3)Based on the AC/DC co-tower erection model and actual project requirements,the above calculation method of AC/DC co-tower hybrid electric field is used.First,the transverse distribution of ground hybrid electric field under the influence of conductor height,conductor type and conductor layout is calculated and analyzed.Secondly,the effects of wind speed,relative humidity and atmospheric particulate matter on ion mobility,corona field strength and space charge density of transmission lines are studied.Mathematical calculation models of electric field under different meteorological factors are constructed,and the distribution characteristics of mixed electric field under the influence of wind speed,relative humidity and atmospheric particulate matter are calculated and analyzed.Finally,the transmission corridor widths at different conductor heights are studied and analyzed with a normalized evaluation method.