One of the main problems the electrical utilities have to cope
with in power distribution systems is the failure of the HIF detection, which may lead to a serious threat in electric shock or/and
fire. These HIFs are caused by a downed energized conductor on
high impedance surfaces, such as dry ground, concrete, gravel,
high resistively soils and asphalt road. Additionally, sometimes
HIFs appear when the energizing conductor makes contact with
grounded objects such as tree limbs. Besides, the high difference of
potential between the two contact points can produce an electric
arc reignition.
In general, the current values that appear due to HIFs are lower
than the overcurrent thresholds, so the phase or residual overcurrent devices remain inactive. Moreover, the resulting current and
voltage waveforms are frequently characterized by random and
intermittent data, caused by the arcing and/or nonlinearity of the
fault impedance, which makes impossible to find single parameters. Hence, the detection of HIFs is really an important challenge
from the public protection and operational reliability point of view.
Although many detection methods have been developed up to now,
a perfect dependable and secure detection is still the objective of
continuous research