

Klaus Moellmann, Abschlussarbeiten 1996
DiplomaThesis 1:
• Regelung des Verdichtens und des Ausspeicherns an Erdgaspipelines.
• Ablöseregelungen bei Durchfluß und Drücken in Verdichterstationen und Erdgasspeichern.
• Abstract "Control of Compression and Decompression at Natural Gas Pipelines"
Control of Compression and Decompression at Natural Gas Pipelines
Override Control for Flow and Pressure in Compressor Stations and Gas Storages
Natural gas has a high acceptance as a fuel with low
environmental pollution. Therefore its use has increased in the
last years and automatic operation of pipeline nets and stations
for different tasks have to be devellopped.
One very frequent task is the control of flow and pressure in
an override function. Only one actuator is used to control these
values by taking care, that neither value gets higher than a
chosen setpoint.That means, only one setpoint can be reached,
whereas the other value stays lower than its setpoint.
Some improvements are presented for typical flow control loops
and for the switchover between the two control tasks assuring
good dynamical properties for both control loops and the change
between them.
The different solutions are compared using system simulations.
So the approach to find a suitable mathematical model has been
also described.
The simulation and the solutions found are tested at the
natural gas storage for the network of GASAG, the company, that
supplies Berlin.
Download STUD_MOE.ZIP "Regelung des Verdichtens und des Ausspeicherns an Erdgaspipelines"
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DiplomaThesis 2:
• Regelschaltungen an Dampferzeugern.
• Die Regelung der Dampftemperatur an einem Überhitzer durch Einspritzung von Speisewasser.
• Abstract "Control Solutions for Steam Generators"
Control Solutions for Steam Generators
Steam Temperature Control at a Superheater by Injection of Feedwater
Steam generators are used in a long industrial history and
their control is done by standard solutions, that are dealt with
in engineering science already numerously. Most of these papers
were based however on analog electronic control. Using PLC, as
done in most realizations nowadays, can cause some effects not
yet described. So the control engineer has to look for the most
suitable solution for PLC use in all the variations known. This
is done here at the example of a steam temperature control.
Furthermore can control be more sophisticated, because
functions can be added easily with PLC use. Nonlinear effects can
improve the control properties.
Some PLC allow the use of fuzzy logic. Can this new approach
bring about better solutions in this well explored area of
superheater control? Some examinations show, that there is
improvement over the linear control, but not over PIDcontrol
with nonlinear gain. This makes fuzzy solutions for this
application unattractive, because fuzzy control involves a lot
more effort in configuration and commissioning than classical
control with some common sense nonlinear additions.
Real improvement can be achieved with state feedback control
with an observer. The paper presents a modification of that
approach, suitable for use of nonlinear or fuzzy additions.
The different solutions are compared using system simulations
at different simplification levels. So the approach to find a
suitable mathematical model has been also described.


