Open AccessDistance protection of multiple‐circuit shared tower transmission lines with different voltages – Part I: fault current magnitude
Author(s) -
Faria da Silva Filipe,
Bak Claus L.
Publication year - 2017
Publication title -
iet generation, transmission and distribution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 110
eISSN - 1751-8695
pISSN - 1751-8687
DOI - 10.1049/iet-gtd.2016.1763
Subject(s) - fault (geology) , voltage , relay , magnitude (astronomy) , tower , electrical impedance , electric power transmission , electrical engineering , mesh analysis , low voltage , transient recovery voltage , voltage source , engineering , physics , dropout voltage , geology , structural engineering , power (physics) , quantum mechanics , astronomy , seismology
Multiple‐circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This study presents a detailed theoretical analysis of such combined faults, including the development of a formula for estimating the magnitude of the short‐circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay at the lower voltage level sees the fault in the reverse direction. The opposite happens if the lower voltage level leads the higher voltage level. It is also demonstrated that the magnitude of fault currents of combined faults is normally slightly larger than of equivalent single‐phase‐to‐ground fault at the higher voltage level. Part II will continue the research work and focus in the fault loop impedance RX diagrams.