Abstract
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Voltage regulation is a crucial practice in distribution
networks to ensure that the steady state voltage levels
at customer connection points are within prescribed limits. In
addition to ensuring required voltage levels, within a range of
power quality problems, voltage unbalance is an important factor
that determines the quality of supply. With regard to voltage
regulation, one of the common methods employed by distribution
network service providers is volt/var control. This method
regulates the voltage of a network by controlling the voltage at
the zone substation and by the injection or absorption of reactive
power at different locations in the network. Typically, volt/var
control is employed in medium voltage networks only, which
overlooks the growth of distributed generation in low voltage
networks. The increasing penetration of distributed generation
may change the paradigm of voltage regulation to the extent
that traditional volt/var control may not be effective. However,
the effects of this increasing penetration can be countered
by exploiting the versatility of distributed generation devices.
This paper proposes a holistic volt/var control approach which
takes into account voltage regulation in both medium and low
voltage networks and voltage unbalance reduction in a low
voltage network. The proposed control method utilises an on
load tap changer and a fixed capacitor bank in the medium
voltage network and also photovoltaic inverters in the low voltage
network. The proposed control is tested on a modified IEEE 13
node test feeder over a 24-hour period over which the load varies.
The results demonstrated that the proposed control method
is able to perform voltage regulation and voltage unbalance
reduction concurrently.