Abstract
The advancement in new technology like fuel cells, wind turbines, and
photovoltaic cells and new innovations in power electronics to satisfy
customer demands for better power quality and reliability are forcing
the power industry to shift to distributed generations (DGs). Hence DG
has recently gained a lot of popularity in the power industry due to
market deregulations and environmental concerns. Islanding take place
when a portion of the distribution system becomes electrically isolated
from the rest of the power system yet continues to be energized by DGs.
The main problem of interconnecting a DG to power distribution system is
islanding. Failure to trip islanded generators can lead to a number of
problems to these generators and the connected loads. All DGs must be
disconnected immediately after the occurrence of islanding. Typically,
this disconnection should be occurred within 100 to 300 ms after the
loss of the main supply. To achieve such a goal, each DG must be
equipped with any islanding detection method. In this paper, active
methods have been introduced to overcome this problem especially the
method of Active Frequency Drift (AFD) as it can detect islanding easily
and has a small Non-Detection Zone, but unfortunately it degrades the
power quality of the system. MATLAB/SIMULINK is used to simulate the
output response of AFD method.