Distributing the loads equally between the distributed
generator (DG) units is an important issue in islanded microgrid
(MG). The inaccurate power sharing may lead to cascaded outage of
the DG units due to the overload and eventually, the MG system will
shut down. Conventional droop control is used widely to perform
power sharing. However, it cannot share load accurately between
DG units due to feeder mismatching. From this perspective, this
work proposes a complex virtual impedance to eliminate feeder
mismatching, compensate for the reactive power sharing errors, and
achieve accurate power sharing between the DG units. In addition,
this work proposes to use an insertion function to insert the virtual
complex impedance to reduce the active power oscillations.
Simulation results, obtained using MATLAB/SIMULINK, show
that the proposed controller can perform accurate power sharing and
is more accurate than conventional droop control with considerably
low active power oscillations. The comparative results with the
conventional virtual complex impedance illustrate the effectiveness
of the proposed approach in terms of controller overshoot, controller
settling time, and circulating current reduction percentage as well as
the effect on the voltage of the point of the common coupling (PCC)
of MG. |
