Environmental Engineering Reference
In-Depth Information
Features and penetration of combined heat and power (CHP) and plug-in hybrid
vehicle (PHEV) devices.
The generic natural gas and electric network features employed have been taken
from specialised distribution network publications [175] and [216]. The base operat-
ing values for pressure and voltage are 7 bar and 11 kV respectively; likewise, the
base power used is 1 MW and 1 MVA.
A UK winter day was chosen for the studies due to the high power consumption,
which is common in this season, thus allowing us to maximise the use of DER
technologies. The natural gas and electrical load profiles used in this study as input
data to run the power flow calculations represent the aggregate demand from 2700
customers. This information is arranged in 48 time intervals. It describes the power
needs of a typical domestic UK winter weekday as seen from the grid supply point.
Both thermal and electrical power demands on a winter weekday are showcased in
Figure 6.1, which are reminiscent of the loads portrayed in Figure 4.13. As Table 6.1
shows, for the day being assessed the thermal demands exceed the electricity needs as
is common during the UK winter season, although in the early hours of the morning
this fact is less evident; nonetheless, the daily demand average nears a 3:1 heat
to power ratio. Besides, another distinction when comparing the load profiles is the
temporal shift of peak demands that occurs before for heat demand than for its electric
counterpart in the early morning and afternoon. This is because priority is given to a
warm environment in enclosed spaces during cold weather conditions.
The simulations performed for the case studies adopt a network similar to the
one depicted in Figure 5.1. This means natural gas and electrical networks consist
of radial structures, as seen in Figure 6.2, possessing four nodes with three linking
elements. For this study, node 2 aggregates 1000 customers, while node 3 sums 800
clients, and node 4 tallies 900 consumers. On the other hand, the control mechanisms
( i.e. compressor and on-load tap changer (OLTC)) are adjacent to their respective
slack nodes for illustration purposes ( i.e. node 1), although these devices can be
modelled at any segment of the network. For simplification purposes it is assumed
that the infrastructures are juxtaposed, meaning they share the same node locations
and element lengths. Similarly for this particular modelling scenario, the first node
in each network is loadless; thus, these nodes solely serve as supply points and
references to the rest of the consumption points.
With regard to embedded devices, it is supposed there are 270 PHEV and micro-
CHP units in each node of the energy service networks. An even penetration will
permit us to assess the strategic value DER technologies and storage facilities have
for distribution network operators (DNOs) as they are dispatched by the TCOPF
coordinator. Likewise, all DER models considered are the same in their performance
specifications; a fact that implies that the capabilities of distributed resources are the
same for all nodes. Consequently, the TCOPF program acknowledges the capacity
and necessities of the connected DER technologies and based on network operating
conditions dispatches them accordingly.
The micro-CHP features modelled are taken from the Panasonic domestic cogen-
eration fuel cell system [218]. This system has an electric power generating efficiency
 
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