Research On Fault Location For Transmission Lines In Common Corridor

When fault occurs on the transmission lines, to locate the fault position accurately and promptly plays an important role in fast line restoration and continuous power supply as well as in the safe and economical operation of power system.This paper focuses on the influence of the mutual inductance between transmission lines in common corridor on the traditional method of one terminal fault location. The cause of the influence is analyzed in depth and the solution to deal with the influence is proposed. The decoupling principle of single and parallel as well as common corridor transmission lines is analyzed. The research shows that to decouple lines in common corridor using six sequence component is not practical. Through careful calculation and analyze the conclusion is drew that inter-line influence only exists in zero sequence after decoupling the lines in common corridor with symmetrical component method.The main principles of fault location using analytical approach are briefly introduced. The influence of mutual inductance on the traditional single line fault location on ground fault condition is analyzed after using the superimposed voltage source and impedance respectively to represent the influence of adjacent line as an equivalent. The formulas show that traditional method of fault location is not effective due to a new unknown plural.To derive a proper algorithm for one-terminal fault location with the influence of mutual inductance, a new method of fault location for single line is proposed. To locate the fault precisely, the first step is using an unknown zero sequence voltage source to substitute the influence of inter-line impedance, and decomposes the fault system into two subsystems which contains single sequence source respectively based on superposition principle. The second step is applying the proposed fault location method to each system separately. From the result provided by the proposed method and the relationship between sequence components in each system, the formula of fault location can be derived. Simulation results show that the proposed fault location algorithm is free from the affect of transition resistance and adjacent lines, and that it is more accurate than traditional method of one-terminal fault location.