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Double circuit transmission lines are frequently subjected to a variety of technical problems from the perspective of protection engineering. These problems are mainly due to the mutual coupling effects between adjacent circuits of the line. In this paper, a new fault location approach for double circuit transmission lines is introduced. It depends only on the data extracted from one end of the line. This practically facilitates implementing and developing this approach, as it needs no information from the other end. The approach is based on modifying the apparent impedance method using modal transformation. Depending on modal transformation, the coupled equations of the transmission line are converted into decoupled ones. This greatly eliminates the mutual effects resulting in an accurate estimation for the fault distance in a straightforward manner. Also the effects of prefault currents, charging currents, and the unknown fault resistance on the estimation accuracy are compensated. The proposed approach was tested via digital simulation using ATP-EMTP in conjunction with MATLAB. Applied test results corroborate the superior performance of the proposed approach.
Date of Publication: Oct. 2003