Research On Coupling Interference Of Parallel AC/DC EHV Transmission Lines

It is the main measure to alleviate the contradiction between grid construction and land resource shortage by using UHV grid technology skills to improve the power transmission capacity and save land resources.With the construction of UHV grid,new lines will inevitably share transmission corridors with existing lines,and transmission lines will become more and more intensive.At the same time,the mixed power transmission of AC and DC lines and the power transmission of the same tower will lead to serious electromagnetic coupling interference between the lines,which will not only affect the maintenance and repair of the lines,but also affect the facilities of the new lines and endanger the safety of the workers.The interference of parallel AC/DC UHV transmission lines is essentially the influence of electromagnetic field.Therefore,this paper first studies the ground hybrid electric field of AC and DC lines,and uses Deutsch's analytical method to solve the DC ionized field.The AC/DC hybrid electric field is calculated according to the calculated DC ionized field.The effects of voltage level of DC line,parallel distance with AC line,phase sequence variation of AC line,conductor height and DC pole spacing on hybrid electric field strength are discussed.Then,based on the inductive power situation in the DC line construction state of AC and DC parallel,the simulation model based on CDEGS is used to calculate the induced voltage and current of different grounding conditions of the DC line.The influence of AC transmission power,parallel distance between AC and DC lines,length of DC parallel AC lines,height of DC lines,soil resistivity and non-full-line coupling of parallel lines on electromagnetic induction current are analyzed,and the relevant influence rules are obtained.On this basis,different grounding schemes during construction of construction lines are discussed,and reasonable grounding schemes in construction are put forward.The research results of this paper can provide a basis for the prevention of induced electricity in UHV transmission lines,and it is of great significance to ensure the safety of construction workers and the safe construction of UHV transmission lines.