Digital distance relaying algorithm for first-zone protection for parallel transmission lines

The paper proposes a new digital distance relaying algorithm for the first-zone protection of parallel power transmission lines. The new method uses data from one end of the protected parallel lines to calculate the fault distance. It is shown that the new method is independent of fault resistance, remote infeed and source impedances, Extensive simulation studies using EMTP have verified that this approach can obtain a highly accurate fault distance estimation within one cycle after fault inception and hence is very much suitable for the digital distance protection of parallel power lines. Applications of this method for fault location are also presented