Modelling embedded technologies in energy service networks - Modelling Distributed Energy Resources in Energy Service Networks - page 78

mobile stochastic load grows in prominence. The ability to model these new load
flows with great level of granularity will become an exciting and major challenge for
power system engineers. These novel power injections will be interrelated to the charg-
ing and discharging of units, also known as grid-to-vehicle (G2V) and vehicle-to-grid
(V2G) flows.
Due to the lack of practical studies regarding wide-range PHEV charging strate-
gies, theoretical modelling of these power injections has become a necessity. To fill
the void of this research gap, some basic charging scenarios can be found in the liter-
ature which aim at portraying the boundary cases PHEV loads might represent on a
daily hourly basis [116]. It must be clarified that these load charging strategies are not
optimised and just represent ideal cases, hence serving as the basis for the TCOPF
criteria employed in the scenarios modelled in Chapter 6. Once developed, these load
patterns can subsequently be aggregated to daily urban electric profiles, consequently
giving a broad idea of the influence PHEV loads can have on electrical distribution
networks.
The basic PHEV G2V strategies elaborated thus far include:

Continuous charging : Assumes that charging occurs in an uncontrolled fashion
whenever vehicles are plugged in. However, it also assumes that public charging
stations are available wherever units are parked. The advantage of this scenario
is that it maximises electric operation and reduces petrol consumption of PHEVs.
This is the business as usual case, also considered the worst-case scenario given
the fact that PHEV charging would begin in the early evening and continue
until the battery is completely full, thus coinciding with the daily peak load
in power systems - specially in residential dwellings. This charging strategy is
depicted in Figure 4.18 [210].

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Delayed charging : Considers vehicle owners plugging-in their units only at
home and without any order, meaning no intelligent controls are employed. This
charging scenario is likely to be realistic when discounted night-time tariffs are
offered ( e.g. economy 7 tariff). This charging strategy is depicted in Figure 4.18
[210].

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The advanced PHEV G2V strategies elaborated thus far consider:

Off-peak charging : Allows plugged PHEVs to charge only at home and taking
advantage of low electricity tariffs at convenient times and when the network is
less stressed. Usually the charging of units would occur after the evening peak,
but as well could occur at midday on the weekend. This approach needs advanced
gear to monitor and control PHEVs to begin drawing power from the grid.

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Smart-charging : Is similar to the previously mentioned off-peak scenario,
although with the difference in assuming that smart public and private charg-
ing stations are available in most parking spaces. This scenario would require
constantly for the local utility to directly or indirectly communicate with the
PHEV units. As a result, the PHEV units could be charged based on state of
the art charging algorithms stakeholders prefer.

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