Modeling and Simulation of an Active Hydraulic Heave Compensation System for Offshore Cranes

Abstract

This thesis deals with the mathematical modeling of hydraulic heave compensation systems. When performing operations such as launch and recovery of remote operated vehicles and lowering subsea installation parts to the sea floor, it is important to attenuate unwanted load motion caused by elongation of the cable and heave motion of the vessel. Quite often, such operations must be put off while waiting for the weather to calm down. Extending the window of operations by developing equipment that can handle varying sea states can result in significant cost savings. There exist both electric and hydraulic heave compensation devices, but the main focus of this thesis is on the hydraulic configurations. A mathematical model is developed in Simulink, and simulations are performed for long-crested seas with values corresponding to the average sea conditions in the North Sea.