Research On Fault Phase Selection And Fault Location For Two-parallel Transmission Lines On Same Tower With Asymmetrical Parameters

Double circuit lines on the same tower can effectively improve the transmission efficiency and reduce the cost of transmission lines.In recent years,it has gradually replaced the previous single circuit as the main transmission line.Because the distance between the double circuit lines on the same tower is relatively close,there is not only the mutual inductance between two phases,but also between the two lines.The fault type is more complex than that of single circuit,which makes the fault phase selection and fault location is difficult.So it is important to study the fault phase selection and fault location method of the double circuit lines on the same tower with asymmetrical parameters,which is of great theoretical and practical significance for the stability of the power grid operation.In this paper,based on the new decoupling method,a new method of fault phase selection and fault location for double circuit lines on the same tower with asymmetrical parameters is proposed.When line fault occurs,the relationship between the current components can be found out by the boundary conditions.If a fault occurs on different lines,the amplitudes of positive sequence components of two lines are different.The amplitudes of the components are the same while the phases are shifted a special angle during the same kind of fault on the different phase of same line.The current and voltage of both ends of the transmission line can be decoupled into the new six sequence component by new six-sequence component method.The fault location formula can be obtained based on that the sequence voltage of fault point calculated by both ends are equivalent.Aiming at a kind of special non identical double circuit transmission line,the fault location method is put forward.PSCAD simulation results show that the method can accurately measure the phase of fault and fault distance,which is not affected by the type of fault,fault location,fault resistance these factors.