CERTS Microgrid control is designed to facilitate an intelligent network of autonomous units. The concept has three critical components, the static switch, the microsources and loads
[4]. The static switch has the ability to autonomously island the
microgrid from disturbances such as faults, IEEE 1547 events
or power quality events. After islanding, the reconnection of the
microgrid is achieved autonomously after the tripping event is
no longer present. Each microsource can seamlessly balance the
power on the islanded microgrid using a power vs. frequency
droop controller. If there is inadequate generation the frequency
will droop below the normal operating range signaling the noncritical loads to shed. The coordination between sources and
loads is through frequency The voltage controller at each source
provides local stability. Without local voltage control, systems
with high penetrations of DG could experience voltage and/or
reactive power oscillations. Voltage control must also insure that
there are no large circulating reactive currents between sources.
This requires a voltage versus reactive power droop controller so
that as the reactive power generated by the source becomes more
capacitive, the local voltage set point is reduced. Conversely, as
reactive power becomes more inductive, the voltage set point is
increased.