Research on the Optimization of the Offset and the Power Consumption for a DP Assisted Mooring System

2013 ◽  
Author(s):  
Hongchao Wang ◽  
Lei Wang ◽  
Hanlin Liu
Keyword(s):  
Power Consumption ◽  
The Other ◽  
Engineering Practice ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Mooring System ◽  
Mooring Lines ◽  
Positioning Accuracy ◽  
Dynamic Positioning System ◽  
Two Measures

DP assisted mooring system is a new positioning system including mooring system and dynamic positioning system. In this paper, two measures are proposed to reduce the offset and the power consumption of a generic semi-submersible platform which is equipped with a DP assisted mooring system during operation. One is to tighten the windward mooring lines and slacken the leeward mooring lines, the other is to reduce or cancel the forbidden angles of the thrusters adjacent to the failed thrusters. Given that the two measures can both reduce the offset and the power consumption of the semi-submersible unit, it is suggested to combine the two measures together to obtain better positioning accuracy. This paper is helpful to engineering practice.

Underwater Thrusters Installation for Dynamic Positioning System of Offshore Floating Vessel

2011 ◽  
Vol 464 ◽  
pp. 163-166
Author(s):  
Jian Jun Zhuang ◽  
Zhen Ying Xu ◽  
Bing Nan Li ◽  
Yun Wang ◽  
Hao Xu ◽  
...  
Keyword(s):  
New Method ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Mooring System ◽  
Floating Platform ◽  
Floating Structure ◽  
Positioning Accuracy ◽  
Precise Position ◽  
Dynamic Positioning System ◽  
Automatic Positioning

Advanced offshore floating structure utilizes dynamic positioning system to guarantee its automatic positioning without mooring system, realizing the offshore positioning requirements. The thruster is the key component of DP whose installation method directly affects the operation of DP and positioning accuracy of offshore floating structure. Based on the analysis of underwater installation methods of the existing large equipment, the paper proposes a new installation method of the large thrusters, using the L-shape floating platform as shift, orientation and position adjustment of thrusters. The new method can complete the precise position matching and installation of thrusters in the bottom of the structure.

An Application of Self-Tuning Fuzzy Controller to Dynamic Positioning System of Floating Production System

1996 ◽  
Vol 118 (4) ◽  
pp. 241-246 ◽  
Author(s):  
Y. Inoue ◽  
J. Du
Keyword(s):  
Fuzzy Control ◽  
Control Strategy ◽  
Production System ◽  
Deep Sea ◽  
Floating Body ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Mooring System ◽  
Dynamic Positioning System ◽  
Self Tuning

Position-keeping of a floating body is a very important matter in a production system in the deep sea. How a floating body can be kept stationary is a key problem in this study. Conventionally, the mooring system is adopted to position a floating body under disturbance of wind, wave, and current; but, in general, it is difficult to survive storm disturbance in the deep sea. The dynamic positioning system can solve this problem, but thrusters must be operated at all times against random drift force of wave, wind, and current, and a great deal of energy is required. So a composite system of single-point mooring system and fuzzy control dynamic positioning (FDP) system was studied in a previous paper (Inoue, 1994). However, up to now in almost all kinds of dynamic positioning systems, control strategy must be decided in advance. This is unreasonable under a random condition. In this paper, a self-tuning fuzzy control system is put forward. By this approach, the control precision of the previous fuzzy dynamic positioning is fairly improved. The main concept of this approach is that at first a feasible control strategy is decided in advance, then during the motion of the system, the control strategy is improved automatically according to the sea conditions of operation. This system is more reasonable than the previous system because, in fact, the disturbance of wave, current, and wind cannot be predicted.

An Optimized Thrust Allocation Algorithm for Dynamic Positioning System Based on RBF Neural Network

2020 ◽  
Author(s):  
Ziying Tang ◽  
Lei Wang ◽  
Fan Yi ◽  
Huacheng He
Keyword(s):  
Neural Network ◽  
Power Consumption ◽  
Optimization Problem ◽  
Hydrodynamic Interaction ◽  
Rbf Neural Network ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Allocation Algorithm ◽  
Dynamic Positioning System ◽  
Thrust Allocation

Abstract The thrust allocation of Dynamic Positioning System (DPS) equipped with multiple thrusters is usually formulated as an optimization problem. Hydrodynamic interaction effects such as thruster-thruster interaction results in thrust loss. This interaction is generally avoided by defining forbidden zones for some azimuth angles. However, it leads to a higher power consumption and stuck thrust angles. For the purpose of improving the traditional Forbidden Zone (FZ) method, this paper proposes an optimized thrust allocation algorithm based on Radial Basis Function (RBF) neural network and Sequential Quadratic Programming (SQP) algorithm, named RBF-SQP. The thrust coefficient is introduced to express the thrust loss which is then incorporated into the mathematical model to remove forbidden zones. Specifically, the RBF neural network is constructed to approximate the thrust efficiency function, and the SQP algorithm is selected to solve the nonlinear optimization problem. The training dataset of RBF neural network is obtained from the model test of thrust-thrust interaction. Numerical simulations for the dynamic positioning of a semi-submersible platform are conducted under typical operating conditions. The simulation results demonstrate that the demanded forces can be correctly distributed among available thrusters. Compared with the traditional methods, the proposed thrust allocation algorithm can achieve a lower power consumption. Moreover, the advantages of considering hydrodynamic interaction effects and utilizing a neural network for function fitting are also highlighted, indicating a practical application prospect of the optimized algorithm.

scholarly journals A Study on the Effectiveness of the Heading Control on the Mooring Line Tension and Position Offset for an Arctic Floating Structure under Complex Environmental Loads

2021 ◽  
Vol 9 (2) ◽  
pp. 102
Author(s):  
Hyun Hwa Kang ◽  
Dae-Soo Lee ◽  
Ji-Su Lim ◽  
Seung Jae Lee ◽  
Jinho Jang ◽  
...  
Keyword(s):  
Standard Procedure ◽  
The Arctic ◽  
Mooring Line ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Station Keeping ◽  
Mooring Lines ◽  
Environmental Loads ◽  
Dynamic Positioning System ◽  
Heading Control

Even though interest in developing the Arctic region is increasing continuously, the standard procedure to be used to analyze the station-keeping performance of a floater considering ice loads has not been established yet. In this paper, the effectiveness of heading control with a dynamic positioning system is analyzed to evaluate the improvement of the performance of the station-keeping system in the ice conditions. Complex environmental loads with ice-induced forces were generated and applied to a ship type floater with dynamic positioning and mooring systems. Three-hour time-domain simulations were conducted for the two different station-keeping systems with mooring only and mooring with a dynamic positioning system. Position offsets and mooring line tensions for the two scenarios were compared with maximum values and most probable maxima (MPM) values. The results of the simulation showed that the heading control can reduce 8.2% of MPM values for the mooring lines and improve the station-keeping performance by about 16.3%. The validity of the station-keeping system that was designed was confirmed, and it is expected that the specification of mooring lines can be relaxed with the heading control.

Modeling and Simulation of Ship Motion for Dynamic Positioning Vessel

2014 ◽  
Vol 919-921 ◽  
pp. 2127-2130
Author(s):  
Pei Wen Yu ◽  
Hui Chen
Keyword(s):  
Modeling And Simulation ◽  
Wind Wave ◽  
Ship Motion ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
Oil Supply ◽  
Mmg Model ◽  
Simulation Results

The paper presents a method to build MMG model of ship motion for a oil supply vessel (OSV) with dynamic positioning system. It is assumed that the ship motion exposed to environment disturbances like wind, wave & currents, The simulation results show that the model of the vessel and environment disturbances are suitable, and the method is practicable .

Research on the Arrangement of the Mooring Lines of the Thruster Assisted Mooring System

2013 ◽  
Author(s):  
Gang Zou ◽  
Lei Wang ◽  
Feng Zhang
Keyword(s):  
Mooring Line ◽  
Mooring System ◽  
Main Function ◽  
Time Domain Simulation ◽  
Mooring Lines ◽  
Dynamic Positioning System ◽  
Optimum Arrangement ◽  
Line Angle ◽  
Mooring Forces ◽  
Offshore Industry

As the offshore industry is developing into deeper and deeper water, station keeping technics are becoming more and more important to the industry. Based on the dynamic positioning system, the thruster assisted mooring system (TAMS) is developed, which consisted of mooring lines and thrusters. The main function of the TAMS is to hold a structure against wind wave and current loads with its thruster and cables, which is mainly evaluated by the holding capacity of the system. The arrangement of the mooring lines (location of anchor or the mooring line angle relative to platform) will directly affect the TAMS holding capacity because of the influence of the directions of the mooring forces. So finding out an optimum arrangement of the mooring lines is essential since the performance of the TAMS depends greatly on the arrangement of the mooring lines. The TAMS of a semi-submersible platform, which is studied in this paper, consisted of eight mooring lines. By fixing the layout of the thrusters and changing the location of each mooring line for every case, the performances of the TAMS are analyzed. The platform motions, mooring line tensions and power consumptions are compared to obtain the optimum arrangement of mooring lines, and thus a thruster assisted mooring system with a better performance can be achieved. Time domain simulation is carried out in this paper to obtain the results.

scholarly journals Dynamic positioning system design for “blue lady”. simulation tests

2012 ◽  
Vol 19 (Special) ◽  
pp. 57-65 ◽  
Author(s):  
Mirosław Tomera
Keyword(s):  
Dynamic Positioning ◽  
Positioning System ◽  
System Operation ◽  
Training Centre ◽  
Dynamic Positioning System ◽  
Operational Quality ◽  
The Mathematical Model ◽  
And Training ◽  
Ship Handling

ABSTRACT The dynamical positioning system is a complex control consisting of a number of components, including: filters, observers, controllers, and propeller allocation systems. The design and preliminary analysis of operational quality of system operation are usually done based on numerical simulations performed with the aid of the mathematical model of the ship. The article presents a concept of the dynamic positioning system applied to steering the training ship Blue Lady used for training captains in the ship handling research and training centre owned by the Foundation for Safety of Navigation and Environment Protection in Ilawa/Kamionka. The simulation tests performed in the numerical environment of Matlab/Simulink have proved the usability of the designed system for steering a ship at low speed.

Sign in / Sign up

Export Citation Format

Share Document