Environmental Engineering Reference
In-Depth Information
These terms are useful to establish the optimal load flow formulation considering the
presence of tap-changing mechanisms in electrical networks.
Once the OLTC equations are introduced into the TCOPF model, the effects
this type of control device can have on electrical networks can be quantified and
analysed, and thus can provide data that might influence voltage-regulation strate-
gies. For instance, the OLTC has the potential to alleviate rises in the voltage level,
which is a major concern that a high presence of DER technologies can have in net-
work operation. A careful coordination between distributed generation sources and
voltage-regulation controllers is key in properly engineering smart-grid networks.
4.2
Modelling compressor stations
4.2.1 Fundamentals of compressor stations
As natural gas is transported in pipelines, the fluid partially loses its initial energy due
to the friction depicted in term (3.35). This frictional resistance translates into a loss
of pressure in the network and hence power losses. To solve this issue, natural gas
systems employ
compressor
stations to provide the pressure needed to transport gas
more effectively from one location to another. The location and pressures at which
these compressor stations function are influenced by many factors, such as range of
operating pipe pressures, availability of power and geotechnical conditions [170]. As
Figure 4.4 shows, similar to electrical systems in which the voltage level must be
carefully monitored, natural gas systems closely monitor the pressure values in their
networks. This makes it necessary to activate the compressor whenever the pressure
levels near their operation limits set by the utility, generally being around
10% [184].
In contrast to electrical networks, where theory implies no power is needed
to control a particular voltage, the regulation of pressure requires power. Thus,
±
pu
±10%
Tolerance
Last
customer
1st Customer
km
Distance of pipeline
City gate
station
Service
Service
Figure 4.4
Pressure drop along a distribution pipeline [174]
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