Civil Engineering Reference
In-Depth Information
Disturbances:
Weather
Renewable energy
Thermal loads
O
p
t
i
m
i
z
a
t
i
o
n
MBPController
{
Cost function
Output signal
(temperature)
Operator
interface
Control signal
PROCESS
Constraints
Process model
Current state
Predictions
Weather
Renewable energy
Demanded load
Fig. 94 MBPC structure for the higher level of the hierarchical control system [
17
]
in which x
h
a
is the process state variable,
T
s
RC
;
T
s
C
;
P
d
ð
k
Þ
T
s
h
oa
ð
k
Þ
T
s
A
¼
1
B
¼
d
ð
k
Þ
¼
þ
ð
57
Þ
C
RC
and T
s
is the sampling time.
The process model, of the form (
55
), is the simplest form possible, in which it is
considered only one heat accumulation. In reality, the process model is more
complex and includes thermal energy storage tanks used in winter and summer
regimes for
“
load shifting.
”
Adopting the model process (
55
) is justi
ed by the need
of a simple presentation of the MBPC principle.
A key step in the formulation of the optimal control problem is the choice of the
performance criterion. It must re
ect a compromise between the requirements of the
thermal comfort and of reducing the energy consumption. There are many concrete
ways of formulating this compromise. In the following is exempli
ed by [
15
] the
selection of criteria and constraints. At each sampling step of the MBPC is required
to solve the following optimization problem:
(
N
u
X
1
T
s
þ j
max u
t
j
;
...
;
min
u
t
þ
kt
u
t
þ
N
u
1t
j
j
u
t
þ
N
u
1
j
e
t
þ
1
j
;
...
;e
t
þ
Ny
j
;
e
t
þ
1
j
;
...
;e
t
þ
Ny t
j
u
t
j
;
u
t
þ
1
j
;
...
;
¼
k
0
ð
58
Þ
h
io
þ q
X
N
x
þ e
t
þ
1 t
e
t
þ
k
j
j
¼
k
1
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