Sensor placement analysis for torsional vibration suppression on marine electric propulsion

The marine industry is seeing an increasing number of vessels equipped with electric propulsion opposed to traditional mechanical propulsion. Electric propulsion has been shown to be advantageous in various land applications such as locomotives and road vehicles however in the marine setting the highly variable hydrodynamic load exposes the electric propulsion system to extreme load conditions. This extreme hydrodynamic load may introduce torsional vibrational over-torque and twist in the shaft as well as introduce disturbances to the electric grid through the electric machine. This paper explores electric control methods, inspired from aerospace gas turbine power generation system, to suppress torsional vibrations. Further the paper highlights that better results may be obtained when speed sensors are placed at specific locations. Finally, the paper compares against another electric control method commonly used in damping control for wind industry, as a base comparison. The works shown in this paper indicates a potential in further studies of electrical control solution to deal with torsional vibration.