Abstract: In the “power cable-overhead line” hybrid transmission line, the line impedance is no longer continuous because the impedance angle of the cable and overhead line is different. If the line parameter difference is ignored,the traditional single-terminal distance measurement algorithm has great influence on the accuracy of fault location .In this paper, an improved single-terminal distance measurement algorithm based on piecewise parameter derivation is proposed based on the impedance homogenization processing method . The impedance of cables and overhead line sections with different impedance angle is segmented evenly. The segmental fault location formula is derived by the segmental parameter derivation method, and the expression of segmental fault distance is presented. Using MATLAB, the hybrid line is modeled and simulated. By comparing the simulation results, error analysis and summary are made. The results show that the distance measurement error of the improved subsection parameter derivation method is smaller.

Key words: hybrid transmission line, fault location, one-terminal method, impedance homogenization, error analysis