Since
the propulsion system makes up a large fraction of the overall power consumption
of an electrically driven ship accurate modeling of the dynamics and their
effects on the overall system is essential for the design process. Dynamic
maneuvers such as reverse of propeller speed or the propeller leaving the
water in high waves are significantly reflected in the signals, such as current,
voltage drops, power frequency, etc., of the electrical system. For example,
during the crash astern maneuver at full ship speed ahead the propeller transits
through a speed where the moving ship actually powers the motor until the
propeller comes to a complete stop. The power produced during this re-generative
period must be either dissipated in breaking resistors or absorbed by the rest
of the electrical system. During this transient, the generators may be forced to
act like motors with the prime mover as the load.
CAPS
is therefore developing real time hardware-in-the-loop simulation capabilities
for electric ship power systems, including propulsion systems. In our test bed,
which will be functional by mid of 2003, we will be able to simulate the dynamic
torque loading on a test motor during ship maneuvers such as the crash astern
maneuver on a 5 MW power level. However, no water and no real propeller will be
necessary to accomplish this. In this context, the experimental setup shall
serve as a (portable) display for an "open house" or for students and
visitors of our lab to emphasize our focus on electric ship propulsion. On a
much smaller scale and to a much more limited extend it should reproduce similar
effects (e.g. electrical current transients and the like) as an observed on real
ships. The real propeller operating in water shall help to explain some of the
dynamic processes in a very descriptive way.
Links: Project Scope Final Design Report Final Design Presentation
Pictures Test Maneuvers Operation Manual