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UID:6282e87129977
DTSTART:20220121T091500Z
SEQUENCE:0
TRANSP:OPAQUE
DTEND:20220121T120000Z
LOCATION:Lecture hall KC:A\, Kemicentrum\, Naturvetarvägen 14\, Faculty of
Engineering LTH\, Lund University\, Lund. Zoom: https://lu-se.zoom.us/j/6
1983095627?pwd=ZWNLMEQ0bThsWGJuL0IvbnUxTEpxUT09
SUMMARY:PhD Defence by Martin Heyden: On the Control of Transportation Netw
orks with Delays
CLASS:PUBLIC
DESCRIPTION:Kontakt: richard.pates@control.lth.se\n\nThesis title: \;On
the Control of Transportation Networks with Delays\n\nAuthor: \;
\;Martin Heyden Department of Automatic Control\, Lund University\n\nOppon
ent: \;Associate professor Laurent Lessard\, Northeastern University&n
bsp\;\n\nWhen: January 21 2022 at 10.15\n\nLocation: \;Lecture hall KC
:A\, Kemicentrum\, Naturvetarvägen 18\, Faculty of Engineering LTH\, Lund
University\, Lund. Zoom: https://lu-se.zoom.us/j/61983095627?pwd=ZWNLMEQ0
bThsWGJuL0IvbnUxTEpxUT09\n\nThesis available: \; \;here\n\n\nAbstr
act:\n\nIn this thesis\, a general model for transportation on directed tr
ee graphs is studied. The nodes in the graph correspond to different stora
ge locations\, and the edges describe between which storage locations tran
sportation is possible. The transportation is assumed to be subject to del
ay. Furthermore\, nodes at the top of the network are allowed to produce m
ore of the studied quantity. As an example\, this setup can model an irrig
ation network\, consisting of several pools that are connected via gates.
The gates allow water to be transported from the upstream to the downstrea
m pool. Each pool can be described by a node\, and the edges describe whic
h pools are connected by a gate. The production corresponds to taking wate
r out from a reservoir and into a pool.\n\nA common approach for control o
f large-scale networks is to stabilize the system around the optimal equil
ibrium point. However\, as the operating conditions of the network change\
, the optimal equilibrium point will also change. In this thesis\, the dyn
amic performance of the network is optimized\, where the cost associated w
ith deviations from the nominal levels is minimized. The transportation va
riations are not penalized\, as it is assumed that this cost is negligible
(for example\, in the case of irrigation networks\, gravity is responsibl
e for the movement).\n\nThe optimal controller is shown to be highly struc
tured\, without imposing any structural constraints on the controller that
normally limit performance. This structure allows for a simple and effici
ent implementation. The optimal transportation assignments can be calculat
ed by a sweep through the graph\, starting in the nodes without children\,
and iterating upwards. This implies that each gate in an irrigation netwo
rk only needs to receive information from the gates downstream and send in
formation to the gates upstream.\n\nEven stronger results are derived for
string graphs. Firstly\, it is shown how to give optimal feed-forward for
planned disturbances. These planned disturbances could for example be farm
ers taking water out of an irrigation network. This requires minor modific
ations to the aforementioned controller structure\, where the information
about the planned disturbances can be communicated by a sweep through the
graph. Secondly\, it is shown how to allow for production in every node. T
his requires two sweeps\, with one going in the upstream direction and one
going in the downstream direction. These sweeps can be done in parallel\,
and thus the implementation time is unaffected. The resulting controller
is applied to a more realistic simulation model for irrigation networks\,
where it outperforms a simple P controller in response to both step change
s and disturbance rejection. For disturbance rejection of low-pass filtere
d disturbances\, the performance is close to the theoretical maximum attai
ned using a centralized controller with a perfect model.\n\nThe optimal co
ntrol problem is also studied from a localized perspective\, where each no
de tries to maximize its own utility. To coordinate\, each node is present
ed with a price for having a certain level at each time point. It is shown
how to calculate prices so that that the nodes’ optimal levels align wi
th the socially optimal levels. These prices can also be calculated by a s
weep through the graph.\n\n\nMer information om händelsen: https://www.lu
.se/evenemang/phd-defence-martin-heyden-control-transportation-networks-de
lays
DTSTAMP:20220517T001233Z
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