Fault Location Algorithm for Three-Terminal Transmission Lines- Distributed Time Domain Line Model

Abstract

Conventional fault location methods using one-terminal voltages and currents are not applicable to multi-terminal transmission lines. However, for determination of fault location in three-terminal lines at least voltages and currents of two terminals are necessary.  There have been some techniques presented to solve fault location problem for multi-terminal transmission lines. In these methods lumped or distributed frequency domain models are used for transmission lines. In multi-terminal lines, faulty section should be detected before fault location estimation. In this paper, two methods based on time domain transmission line model are presented to identify the faulty section and to determine the location of faults for three terminal transmission lines. In the first method, samples of voltages and currents from all terminals are used while in the second method only the data of two terminals is used for calculating the location of the fault. The proposed algorithms are independent of fault resistance, insensitive to load current and fault inception angle. Furthermore they do not require any knowledge of source impedance and also fault type classification is not necessary. Filtering of dc and high frequency component of waves are not required. The results of computer simulation using EMTP/ATP software confirm the accuracy and precision of the proposed methods.