III. REVIEW OF HIF MODEL
The Arcing associated with the HIFs
results in energy dissipation in the form of heat that
turns the moisture in the soil into steam and burns
the grass into smoke. In the arcing phenomenon
associated with downed power lines, due to the
existence of air between ground and conductor, the
high potential difference in such a short distance
excites the appearance of the arc. Also, arcing often
accompanies these faults, which poses a fire
hazard. Therefore, from both public safety and
operational reliability viewpoints, detection of
HIFs is critically important. High impedance fault
is a difficult case to model because most HIF
phenomena involve arcing, which has not been
perfectly modeled so far. Some previous
researchers have reached a consensus that HIFs are
nonlinear and asymmetric, and that modeling
should include random and dynamic qualities of
arcing. Emanuel model is based on laboratory
measurements and theoretical components [1]
suggested two dc sources connected anti-parallel
with two diodes to simulate zero periods of arcing
and asymmetry as seen in Figure 4.