The use of Floating Production storage and Offloading (FPSO) units for the production and storage of oil is quite common in deep water. The produced crude oil is normally transported by a shuttle tanker. During offloading the tanker has to keep certain position with a mooring system or dynamic positioning (DP) system. The dynamic positioning system is able to demonstrate excellent performance of keeping the desired position and heading of vessels in the presence of external disturbances, especially in deep water. In this paper, a heading control DP System supplied by Siemens onboard a FPSO is simulated by Oceanic's SML simulation software. The PID algorithm was developed to derive the command load from the ship response (motions, wind force and current load) and then to find the command of each thrusters and controllable pitch propellers. The proposed controller is robust with respect to modeling errors and variations in the intensity and direction of environmental forces. The linking of the SML simulation software to Siemens DP controller is described and simulations to verify the DP controller response to various environment conditions are presented.
In recent decades, the use of ship-type offshore units for the production and storage of oil has become a common method. Located permanently at a certain place at sea, the Floating Production Storage and Offloading (FPSO) vessels have become the major floating production units. The produced crude oil is normally transported by a shuttle tanker. During the offloading operation, the change of the FPSO heading relative to the tandem moored shuttle tanker are very important. During offloading the tanker has to keep certain position with a mooring system or dynamic positioning (DP) system. The DP system for station keeping has advantages compared with mooring system in deep water condition.