Study On Electromagnetic Coupling Between Parallel Transmission Lines And Effects

With the increasing demand for electricity and the shortage of land resources in China,the parallel construction of transmission lines on the same tower or the same transmission corridor has become an inevitable trend in the development of power grids.The increasingly tight line corridors make the electromagnetic environment around parallel lines very complicated,and the electromagnetic coupling between lines is particularly serious,which poses a huge threat to the safety of maintenance personnel and electrical equipment.When an asymmetrical ground fault occurs in one of the parallel lines,the electromagnetic coupling between the lines can increase the potential supply current at the fault point,resulting in the arc not easy to extinguish,affecting the safe and stable operation of the power system,and at the same time making the adjacent normal operation lines Large negative sequence and zero sequence currents are generated,causing problems such as malfunction of non-faulty line protection devices or damage to generators,which affects the accurate operation of power system relay protection devices and the accurate measurement of transmission line parameters.Therefore,it is of great significance to carry out research on the influence of electromagnetic coupling between parallel transmission lines.In this paper,the double-circuit transmission line on the same tower is used as a model.By analyzing the electromagnetic coupling mechanism between the transmission lines,the characteristics and calculation methods of induced voltage and induced current on the line are obtained.Resistivity,loop spacing,line coupling length,line transposition and other factors affect the law of line electromagnetic coupling components.According to the characteristics of 500 k V EHV transmission line,the optimal transposition method of transmission line is selected to minimize the influence of electromagnetic coupling on the induced voltage,current and imbalance on the line.By analyzing the changes of positive,negative,and zero-sequence inductive components on the line under the action of electromagnetic coupling,the effect of electromagnetic coupling between parallel lines on the power system was studied,including the problem of parallel transmission line parameter measurement,relay protection setting,grounding The choice of switches,etc.,draws the influence and feasible measures of the electromagnetic coupling between parallel lines on the stable operation of the power system.