For many offshore activities, including offshore oil and gas exploration and offshore wind farm construction, it is essential to keep the position and heading of the vessel stable. The dynamic positioning system is a progressive technology, which is extensively used in shipping and other maritime structures. To maintain the vessels or platforms from displacement, its thrusters are used automatically to control and stabilize the position and heading of vessels in sea state disturbances. The theory of dynamic positioning has been studied and developed in terms of control techniques to achieve greater accuracy and reduce ship movement caused by environmental disturbance for more than 30 years. This paper reviews the control strategies and architecture of the DPS in marine vessels. In addition, it suggests possible control principles and makes a comparison between the advantages and disadvantages of existing literature. Some details for future research on DP control challenges are discussed in this paper.
Concerns about the impact of global warming caused by air pollution and depletion of fossil fuels have attracted attention and opportunities in transportation especially in maritime industry. In all electric ships, the electrical equipment including electric propulsion is connected to the common ship electrical network to achieve better fuel consumption with less emission. However, the low-load factor of the parallel diesel generators (DGs) in some operating conditions, can negatively affect the fuel consumption rate. As an alternative, two or more power sources such as batteries and renewable-based prime movers can be integrated into the system aboard to improve the overall system performance. By optimal scheduling of the power sources, poor low-load efficiency can be avoided and controllable units can be dispatched in an emission-aware and cost-effective manner. This paper analyzes how much the operating cost of a shipboard system can be improved (based on estimation of specific fuel consumption (SFC) curve of a real system) considering the dynamic load profile with and without energy storage systems (ESSs). The case study in this paper is a ferry with a conversion from traditional diesel mechanical power to electrical propulsion powered by DGs and ESSs.
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