Dynamic Model Predictive Control for Load Sharing in Electric Power Plants for Ships
The main contribution of this thesis is an investigation of model predictive control
(MPC) for marine diesel electric power plants. Recommendations and new ideas
for further development are emphasized.
The motivation of the thesis is to develop a controller for diesel electric power plants
that can control the plant in a more efficient way. This includes reducing wear and
tear, fuel consumption, and emissions. However, the safety aspect is always the
most important factor and must be handled with care.
The case plant to be studied is a diesel electrical power plant consisting of several
diesel driven generators (genset). These gensets produce electrical power to serve
the electrical demands on a marine vessel. The consumers can be propulsion units,
heave compensators, drilling equipment, and hotel loads. These highly dynamic
consumers are large compared with the producers. This gives unwanted fluctuation
of frequency. In some vessels this effect is so large that more gensets are required
for transients than for peak demands. This can be avoided with better control
The controller developed in this thesis adjusts the local controllers on the diesel
engines. The objective is to keep the genset at a given load sharing, while keeping
the frequency within rules and regulations. In addition is the plant controlled to a
state where a single point failure does not lead to blackout.
Blackout is prevented by calculating a failure case in addition to the normal case.
The failure case may be a disconnection of the largest genset on the power bus
segment. The case is calculated in the controller to make sure that if the case
occurs the plant is able to handle the failure without a blackout. A normal case,
where everything goes as normal, is calculated to optimize the current operation.
The controller is verified by simulation done in MATLAB/Simulink. The
implemented controller performs well during all of the simulated cases. However,
the predictions made by the controller are in some cases conservative. This is due
to the choice of the fuel rate constraints. Lastly, suggestions for how to improve
the performance of the controller are included. The most important suggestions
are to include a model of the turbocharger in the control plant model and to
include more failure cases.
Place, publisher, year, edition, pages
Institutt for marin teknikk , 2012. , 122 p.
ntnudaim:7545, MTMART Marin teknikk, Marin kybernetikk
IdentifiersURN: urn:nbn:no:ntnu:diva-18749Local ID: ntnudaim:7545OAI: oai:DiVA.org:ntnu-18749DiVA: diva2:566241
Skjetne, Roger, ProfessorJohansen, Tor Arne