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@ARTICLE{Caspari:877453,
author = {Caspari, Adrian and Tsay, Calvin and Mhamdi, Adel and
Baldea, Michael and Mitsos, Alexander},
title = {{T}he integration of scheduling and control: {T}op-down vs.
bottom-up},
journal = {Journal of process control},
volume = {91},
issn = {0959-1524},
address = {Amsterdam [u.a.]},
publisher = {Elsevier Science},
reportid = {FZJ-2020-02206},
pages = {50 - 62},
year = {2020},
abstract = {The flexible operation of continuous processes often
requires the integration of scheduling and control. This can
be achieved by top-down or bottom-up approaches. We compare
the two paradigms in-silico using an air separation unit as
a benchmark process. To demonstrate the top-down paradigm,
we identify data-driven models of the closed-loop process
dynamics based on a mechanistic model and use them in
scheduling calculations that are performed offline. The
resulting target trajectories are passed to a linear model
predictive control (LMPC) system and implemented in the
process. To demonstrate the bottom-up paradigm, we define an
economic nonlinear model predictive control (eNMPC) scheme,
which performs dynamic optimization using the full model in
closed-loop to directly obtain the control variable profiles
to be implemented in the process. We provide implementations
of the process model equations as both a gPROMS and a
Modelica model to encourage future comparison of approaches
for flexible operation, process control, and/or handling
disturbances. The performance, advantages, and disadvantages
of the two strategies are analyzed using demand-response
scenarios with varying levels of fluctuations in electricity
prices, as well as considering the cases of known,
instantaneous, and completely unknown load changes. The
similarities and differences of the two approaches as
relevant to flexible operation of continuous processes are
discussed. Integrated scheduling and control leverages
existing infrastructure and can be immediately applied to
real operation tasks. Both operation strategies achieve
successful process operation with remarkable economic
improvements (up to $8\%)$ compared to constant operation.
eNMPC requires more computational resources, and is – at
the moment – not implementable in real-time due to maximum
optimization times exceeding the controller sampling time.
However, eNMPC achieves up to 2.5 times higher operating
cost savings compared to the top-down approach, owing in
part to the more accurate modeling of key process dynamics.},
cin = {IEK-10},
ddc = {004},
cid = {I:(DE-Juel1)IEK-10-20170217},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000543364100005},
doi = {10.1016/j.jprocont.2020.05.008},
url = {https://juser.fz-juelich.de/record/877453},
}