Environmental Engineering Reference
In-Depth Information
As the above figures illustrate, once DER technologies become prominent, oper-
ating variables in each energy infrastructure will vary based on the penetration and
the many technical attributes embedded devices possess, such as the electricity-to-heat
ratio for cogeneration units and the charge rating of PHEV units.
In this specific example, which only analyses one time interval, the voltage lev-
els rise and benefit from the power injections provided by the distributed resources.
On the other hand, due to cogeneration use pressure levels decrease; however, these
variations do not threaten appropriate operating conditions on any network. There-
fore, at least for the case scenario presented, embedded technologies do not represent
instability to the operability of natural gas and electrical distribution networks. Nev-
ertheless, attention should always be given to these parameters whenever a study is
conducted to guarantee that no statutory limits are breached.
In addition, the figures show that the cost per unit of power delivered by
DNOs is another type of result the TCOPF program offers; this data is referred to
as locational marginal costs or nodal incremental costs . Since the energy systems
are composed of several interconnected nodes, each node is subjected to different
LMC. The LMC value in each node is done by summing the derivative of the sup-
ply point fuel cost function ( i.e. slack bus) plus the influence power losses have on
that particular node.
As detailed in Table 6.7, the marginal price results are influenced by the ability
of the distributed resources to convert and provide power closer to the consumption
points. Thus, as seen from the grid supply points the load profiles as well as the
costs associated with their provision are affected. For this particular example, since
less electricity is required from the grid the consumption points will see a fall in
price. However, in natural gas the costs increase since cogeneration technologies
will demand more fluid. Consequently, it can be assumed that as embedded technology
penetration increases, natural gas marginal costs will go up (as long as the thermal
efficiency of cogeneration units are lower than boilers), while the reverse effect can be
expected for electricity marginal costs (as long as the influence of PHEV penetration
is lower than micro-CHPs).
Saving opportunities exist if marginal cost differentials can be exploited through
an optimal coordination of energy systems. For instance, in the 'before case' the
LMC at node 4 is £13.39 per PU of electricity and £7.59 per PU of natural gas,
while in the 'after case' the LMC at node 4 is £13.22 per PU of electricity and
Table 6.7
Comparison of LMC results at 7 p.m.
Node number
Before LMC
After LMC
Before LMC
After LMC
electricity
electricity
natural gas
natural gas
1
13.32
13.17
7.42
7.46
2
13.36
13.20
7.54
7.60
3
13.38
13.21
7.58
7.64
4
13.39
13.22
7.59
7.65
 
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