Environmental Engineering Reference
In-Depth Information
5.3.1.4
For energy cost minimisation
⎡
⎤
nG
g
nP
g
nβ
⎣
⎦
min
G
Pα
,
β
+
P
Pα
,
β
(5.4)
β
=
1
α
=
1
α
=
1
⎧
⎨
α
is the unit index being analysed
β
is the time interval being analysed
nβ
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
Pα
,
β
is the spot market natural gas cost for supplying point
α
in time
β
P
Pα
,
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:
⎡
⎤
nβ
nG
g
nP
g
⎣
⎦
E
total
P
G
total
P
P
total
P
=
+
=
G
Pα
,
β
+
P
Pα
,
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
nβ
⎣
(ω)
⎝
⎠
·
G
Eα
,
β
+
min
P
Eα
,
β
β
=
1
α
=
1
α
=
1
⎛
⎞
⎤
nG
g
nP
g
⎝
⎠
⎦
+
(
1
−
ω)
·
G
Pα
,
β
+
P
Pα
,
β
(5.6)
α
=
1
α
=
1
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