Abstract:
Nowadays, renewable energy sources (RES) are
widely used in the distribution system. Despite the advantages of
RES in the system, they also introduce some problems such as
unintentional islanding, protection concerns, reverse power flow,
etc. Due to the unpredictable faults or scheduled maintenance
plans, a distribution system can be sectionalized into several
islands provided that enough dispersed generation units are available.
Thus, distribution systems should be capable of detecting
islanding condition for smooth transition to an islanded mode. As
a first step, an islanding detection method (IDM) is proposed in
this paper to detect the islanding phenomenon in a distribution
system. The proposed method is a hybrid IDM which consists of a
remote detection method and a passive method. In the next step, an
adaptive control strategy is proposed to ensure stable operation of
islanded subsections. The proposed method utilizes error rates of
system parameter such as voltage and power to readjust generator
controllers and maintain the system stability. The proposed IDM
and adaptive controller are implemented on a generic distribution
network using EMTDC/PSCAD software. Results have shown that
the hybrid detection method is capable of detecting the islanding
in the presence multiple distributed generation units. Moreover,
the proposed IDM is not affected by load/generation changes.
Results also showed a smooth transition from grid-connected
mode to autonomous operation mode. Furthermore, the proposed
adaptive control strategy maintains stable operation of the island
when fault occurs in the island.
