Environmental Engineering Reference
In-Depth Information
5.3.1.4
For energy cost minimisation
nG g
nP g
min
G , β +
P , β
(5.4)
β
=
1
α
=
1
α
=
1
α is the unit index being analysed
β is the time interval being analysed
is the number of time intervals into which the full period is divided
nG g is the number of supply points in the natural gas network
nP g is the number of supply points in the electrical network
G , β is the spot market natural gas cost for supplying point α in time β
P , β is the spot market electricity cost for supplying point α in time β
Note : The energy costs are determined by multiplying the cost of energy (from
the day-ahead market) times the amount of energy being supplied. After obtaining the
total costs of providing natural gas and electricity, G total
where
P and P tota P respectively, these
variables are then added, so the total energy costs of the urban energy system can be
calculated, as stated by the following equation:
nG g
nP g
E total
P
G total
P
P total
P
=
+
=
G , β +
P , β
(5.5)
β
=
1
α
=
1
α
=
1
E total
P
is the total cost of energy consumed at spot market prices
G total
P is the total cost of natural gas energy consumed at spot market prices
P tota P is the total cost of electrical energy consumed at spot market prices
α is the unit index being analysed
β is the time interval being analysed
where
Statement (5.4) focuses on minimising the energy costs incurred while sup-
plying electric and natural gas to the consumers based on spot market prices, this
is naturally measured in monetary units (refer to subsection 5.2.4 for a greater
explanation).
5.3.1.5
For composite objective minimisation ( e.g. cost of spot prices
vs. cost of emissions)
nG g
nP g
(ω)
·
G , β +
min
P , β
β
=
1
α
=
1
α
=
1
nG g
nP g
+ ( 1
ω) ·
G , β +
P , β
(5.6)
α
=
1
α
=
1
 
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