Fault impedance analysis and non-conventional distance protection settings for half-wavelength transmission line applications

Abstract

This paper presents an analysis of fault phase impedance and its dynamic response for half-wavelength (HWL) transmission lines. One important issue of this technology is fault protection as distance protection elements are based on impedance for conventional AC lines. HWL line has very long length, preventing the direct application of classical impedance method because the capacitance effect produces different impedance behavior. This paper analyzes and characterizes the phase impedance response, and proposes alternative distance protection settings focusing on solving the problem of line-to-line fault detection. It is proven that the algorithm covers 84% of the line length. However, faults in the central region have a high resistance characteristic and cannot be detected with the proposed method. The paper takes into account the influence of line transpositions that further affects the protection performance near central region. Transient analysis and software in the loop tests were performed with PSCAD/EMTDC.