Asymmetric issues caused by un-transposed transmission lines and its solution

The major obstacle nowadays in short-distanced(generally refers to distance less than 100 km) transmission line with two circuits on the same tower is the asymmetry of 3-phase current caused by the untransposition of transmission line.This paper simulates the 3-phase asymmetrical phenomenon in a 220 kV ring transmission system,using electromagnetic transient status and 3-phase power flow calculation method based on current injection,to demonstrate the validity of the 3-phase current injection method.T he result indicates that the asymmetrical phenomenon can be improved by the inverse transposition of each circuit with inverse order of the phase arrangement.