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.

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.

Time Domain Simulation of a Dynamic Positioning Deepwater Semisubmersible Drilling Platform

2014 ◽  
Author(s):  
Xu Yang ◽  
Liping Sun ◽  
Shuhong Chai
Keyword(s):  
Time Domain ◽  
Numerical Study ◽  
Angular Speed ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Time Domain Simulation ◽  
Proportional Integral Derivative ◽  
Floating Structures ◽  
Environmental Loads ◽  
Dynamic Positioning System

DPS (dynamic positioning system) has been widely used in floating structures, especially in deepwater area. Time domain simulation of platforms with dynamic positioning system has great significance to DP capability and riser system. Motion response of a deepwater semi-submersible platform with DPS on time domain was presented in this paper. PID (proportional, integral, derivative) controller and thruster allocation method were applied in numerical simulations of DPS. Wind, current and wave environmental loads were analyzed and limited angular speed was considered as well. Thruster failure analyses were covered and discussed also. Experiments of DPS in deep-water basin of Harbin Engineering University (HEU) were presented and compared with numerical study.

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 .

Damage Detection of Offshore Platform Mooring Line Using Artificial Neural Network

2018 ◽  
Author(s):  
Djoni E. Sidarta ◽  
Jim O’Sullivan ◽  
Ho-Joon Lim
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Damage Detection ◽  
Total Mass ◽  
Offshore Platform ◽  
Mooring Line ◽  
Ann Model ◽  
Station Keeping ◽  
Mooring Lines ◽  
Artificial Neural

Station-keeping using mooring lines is an important part of the design of floating offshore platforms, and has been used on most types of floating platforms, such as Spar, Semi-submersible, and FPSO. It is of great interest to monitor the integrity of the mooring lines to detect any damaged and/or failures. This paper presents a method to train an Artificial Neural Network (ANN) model for damage detection of mooring lines based on a patented methodology that uses detection of subtle shifts in the long drift period of a moored floating vessel as an indicator of mooring line failure, using only GPS monitoring. In case of an FPSO, the total mass or weight of the vessel is also used as a variable. The training of the ANN model employs a back-propagation learning algorithm and an automatic method for determination of ANN architecture. The input variables of the ANN model can be derived from the monitored motion of the platform by GPS (plus vessel’s total mass in case of an FPSO), and the output of the model is the identification of a specific damaged mooring line. The training and testing of the ANN model use the results of numerical analyses for a semi-submersible offshore platform with twenty mooring lines for a range of metocean conditions. The training data cover the cases of intact mooring lines and a damaged line for two selected adjacent lines. As an illustration, the evolution of the model at various training stages is presented in terms of its accuracy to detect and identify a damaged mooring line. After successful training, the trained model can detect with great fidelity and speed the damaged mooring line. In addition, it can detect accurately the damaged mooring line for sea states that are not included in the training. This demonstrates that the model can recognize and classify patterns associated with a damaged mooring line and separate them from patterns of intact mooring lines for sea states that are and are not included in the training. This study demonstrates a great potential for the use of a more general and comprehensive ANN model to help monitor the station keeping integrity of a floating offshore platform and the dynamic behavior of floating systems in order to forecast problems before they occur by detecting deviations in historical patterns.

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.

scholarly journals Analysis of Impact of Ship Model Parameters on Changes of Control Quality Index in Ship Dynamic Positioning System

2019 ◽  
Vol 26 (1) ◽  
pp. 6-14 ◽  
Author(s):  
Tacjana Niksa Rynkiewicz ◽  
Anna Witkowska
Keyword(s):  
Quality Index ◽  
Adaptive Controller ◽  
Model Parameters ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Integral Control ◽  
Dynamic Positioning System ◽  
Ship Model ◽  
Control Quality ◽  
The Impact

Abstract In this work there is presented an analysis of impact of ship model parameters on changes of control quality index in a ship dynamic positioning system designed with the use of a backstepping adaptive controller. Assessment of the impact of ship model parameters was performed on the basis of Pareto-Lorentz curves and ABC method in order to determine sets of the parameters which have either crucial, moderate or low impact on objective function. Simulation investigations were carried out with taking into account integral control quality indices.

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