Environmental Engineering Reference
In-Depth Information
ABB
ABB Expert Optimizer [47] is a hybrid intelligent system designed primarily for
expert closed-loop process control and industrial process optimization, but can also
be used for decision support applications. Figure 7.4 depicts the concept of the con-
trol algorithm; see European Patent EP1553470 [48]. It is based on a mathematical
model of the process being controlled, for example:
dx
dt
=
(
,
,
)
(
,
,
)=
,
f
t
x
u
;
h
t
x
u
0
(7.2)
where
x
is the system state and
u
is the control variable. The algorithm uses optimal
control (OC) and/or MPC techniques to select the ES targets
U
. ES keeps the process
variables within certain bounds or close to predefined target values acting on the
control variables
C
. OC and MPC work by minimizing the functional
T
J
[
x
(
0
),
u
]=
L
(
τ
,
x
(
τ
),
u
(
τ
))
d
τ
(7.3)
0
with respect to
u
, subject to the constraints imposed by the mathematical model of
the extended system given by the process P and the expert system ES. This model
is a hybrid in the sense that both continuous dynamics (mostly process) and logical
relationships (mostly ES) appear in it. A mixed logical dynamical system approach
is recommended for modeling the extended plant.
Figure 7.4
ABB control algorithm concept
In the scheme shown in Figure 7.4, ES is concerned with process stability while
the OC/MPC lock takes care of optimality, that is, either OC or MPC drives pro-
cesses to their economically optimal point. The performance criterion
J
is therefore
related to some sort of economic performance measure.
Search WWH ::
Custom Search