Information Technology Reference
In-Depth Information
mode and the start-up cost for such units is small. Hence, the start-up cost STi
i
can
be modeled by the following function system:
OFF
i
HSC
i
si MDTi
i
s
MDT
i
þ
SC
i
ST
i
¼
ð
3
Þ
OFF
i
CSC
i
si
s
MDT
i
þ
SC
i
with:
a
i
, b
i
and c
i
Coef
cients of the production cost,
P
ih
Active power generated by the ith unit hth hour, i =1,2,3,
…
, N
g
and h =1,2,3,
…
., H
U
ih
On/off status of the ith production unit at the hth hour, U
ih
= 0 for the
Off status of one generating unit and U
ih
= 1 for the operating status
of one generating unit,
HSC
i
Hot start-up cost of the ith unit,
CSC
i
Cold start-up cost of the ith unit,
MDT
i
Minimum down-time of the unit i,
τ
i
OFF
Continuously off-time of unit i,
SC
i
Cold start time of unit i,
N
g
Number of generating units,
H
Time horizon for UC (h).
Unit Commitment is a highly constrained optimization problem. Different power
systems have a different set of imposed constraints. The most common can be
divided into two categories. The
first, called unit constraints, represents the con-
straints that are applied to the single units; the second type, system constraints,
contain those that are applied to the whole power system.
System Constraints
Power balance constraints:
At any time over the planning horizon the total real power generation of the
system must be equal to the total demand.
-
N
g
X
P
ih
U
ih
P
dh
P
Lh
¼
0
ð
4
Þ
i¼1
Spinning reserve constraints
-
X
N
g
U
i
P
i
P
dh
þ
P
rh
þ
P
Lh
ð
5
Þ
i¼1
Search WWH ::
Custom Search