Identification of Free Components during Non-Simultaneous Complex Faults in Overhead Lines: A Review

Abstract

This study concerns the identification and interpretation of current and voltage signals during complex non-simultaneous disturbances in high-voltage overhead lines. It includes topics related to both the search for the optimal model of the system during complex disturbances as well as the analysis of the obtained results. The available EMT-like tools for the analysis of these phenomena are discussed. Models of high voltage overhead transmission lines are presented along with a discussion of their suitability for the study of electromagnetic transients during the analysis of complex non-simultaneous faults. Examples of transient waveforms of currents and voltages during non-simultaneous faults are presented, and the conditions for the occurrence of delayed current zero during short circuits in the system are discussed. The maximum values of the overvoltage factors and the conditions of their occurrence are described. Faults in transmission lines with various voltage levels suspended on the same supporting structures are discussed, together with an indication of the dangerous consequences of unusual intersystem faults. In the final part of the paper, the summary and recommendations for non-simultaneous fault studies are presented.