Fault location for three-terminal transmission lines using fault voltage sequence components

Abstract

ABSTRACTA new fault location algorithm for three-terminal high or extra-high voltage transmission lines is presented and validated. The algorithm is based on the transmission line model with lumped parameters considering the distributed capacitance of lines. Only the sequence component of fault voltage is used in fault location to avoid the influence of saturated current transformer. In location formulas, positive sequence components are used for symmetric faults and negative sequence components are used for non-symmetric faults. The schemes for the following three different conditions of three-terminal lines are discussed in detail: single-circuit line with T-connection networks, single-circuit line to double-circuit line with T-connection networks, double-circuit line with T-connection networks. A new faulted branch selection method is proposed. The hypothetical fault distance of each branch is calculated and compared to accurately determine which branch is faulty. ATP simulation indicates that the location precision is satisfied no matter the measurements are synchronised or unsynchronised at three terminals. A quantitative comparison with the other known algorithms reveals that the presented new algorithm has higher location accuracy and can judge fault branch more accurately.