Estimation of Dynamic Positioning performance by time-domain simulations—a step toward safer operations

2014 ◽  
pp. 117-124 ◽  
Keyword(s):  
Time Domain ◽  
Dynamic Positioning

Time-Domain Dynamic Analysis for Dynamic Positioning System of Deepwater Semi-Submersible

2012 ◽  
Vol 204-208 ◽  
pp. 4518-4522 ◽  
Author(s):  
Li Ping Sun ◽  
Shu Long Cai ◽  
Jing Chen
Keyword(s):  
Dynamic Analysis ◽  
Deep Water ◽  
Time Domain ◽  
Pid Control ◽  
Oil And Gas ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Dynamic Positioning System ◽  
The Time Domain ◽  
Thrust Allocation

Semi-submersible plays an important role in ocean oil and gas exploitation. This paper carried out some researches for the dynamic positioning system (DPS) of a deep water semi- submersible. Mathematic modal was made, and a special program was created with M-language for the time-domain dynamic analysis of the dynamic positioning system of the deep water semi-submersible, on basis of the mathematic modal. PID control strategy, kalman filtering theory and optimal thrust allocation method were used in the analysis. Simulation result indicated the DPS of this platform is safe and efficient.

A Fast Method for the Evaluation of the Dynamic Positioning Capability in Time Domain in the Early Design Stage

2015 ◽  
Author(s):  
Adele Luebcke ◽  
Philip Augener ◽  
Arne Falkenhorst
Keyword(s):  
Time Domain ◽  
Wind Waves ◽  
Ship Design ◽  
Propulsion System ◽  
Design Stage ◽  
Maximum Deviation ◽  
Dynamic Positioning ◽  
Fast Method ◽  
Fast Calculation ◽  
Early Design Stage

Vessels equipped with a Dynamic Positioning (DP) system for station keeping have become quite common on the offshore market. The propulsion system of such ships has the capability to compensate the counteracting environmental forces caused by wind, waves and current. Since the DP capability is an important part of the specification, it is necessary to consider this aspect in the early ship design stage. For this purpose a procedure of a fast calculation method is developed by the authors to predict the limiting environmental conditions and the maximum deviation of the position and the course angle for a pre-established propulsion system.

scholarly journals Tuning for robust and optimal dynamic positioning control in BlueROV2

2021 ◽  
Vol 1201 (1) ◽  
pp. 012015
Author(s):  
X Yang ◽  
Y Xing
Keyword(s):  
Time Domain ◽  
Sensitivity Study ◽  
Measurement Noise ◽  
Pid Controllers ◽  
Base Case ◽  
Dynamic Positioning ◽  
Noise Levels ◽  
Positioning Control ◽  
Optimal Dynamic ◽  
Linearized Model

Abstract A tuning approach for the robust and optimal dynamic positioning control of BlueROV2 subjected to currents with varying speeds and headings is presented. A 2D planar dynamic model of BlueROV2 is developed in Matlab/Simulink and used for the study. The surge, sway and yaw motions are controlled by individual PID controllers. An extensive sensitivity study is carried out on a total of nine cases with different current speeds, current headings, and measurement noise levels. The results show that tuning a model solely using step responses from a linearized model might not produce optimal results. Further it is important to verify the system responses in time domain after tuning. Finally, it is observed that re-tuning the controllers for each simulation case may lead to better performance. However, it is also shown that the base case controller gains are sufficiently robust and lead to good performances for the other simulation cases.

Current Feed Forward Control in Dynamic Positioning

2011 ◽  
Author(s):  
M. R. Smit ◽  
A. R. Tjallema ◽  
R. H. M. Huijsmans
Keyword(s):  
Standard Deviation ◽  
Time Domain ◽  
Control Point ◽  
Dynamic Positioning ◽  
Horizontal Position ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Performance Time ◽  
The Mean ◽  
Internal Soliton

The presented research investigates to what extent current feed forward control improves the positioning performance of Dynamically Positioned (DP) Floating Production Storage and Offloading (FPSO) vessels in varying currents. Positioning performance refers to the accuracy of positioning (both heading and horizontal position) and the associated power usage. Tidal current reversals and so called ‘internal soliton’ currents are examples of varying currents, in which current feed forward control is expected to improve positioning performance. Time domain simulations are carried out using the DpSim software, as developed by the Maritime Research Institute Netherlands (MARIN). In this research project, the DpSim software is extended with a module containing current feed forward control. When current feed forward control is applied in DP in varying currents, the mean and standard deviation of the control point excursion are reduced. The heading performance and power usage do not change significantly while achieving this reduction.

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.

scholarly journals Fuel-Optimal Thrust-Allocation Algorithm Using Penalty Optimization Programing for Dynamic-Positioning-Controlled Offshore Platforms

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2128 ◽  
Author(s):  
Se Kim ◽  
Moo Kim
Keyword(s):  
Quadratic Programming ◽  
Time Domain ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Time Domain Simulation ◽  
Allocation Algorithm ◽  
Dynamic Positioning System ◽  
Fully Coupled ◽  
Pseudo Inverse ◽  
Thrust Allocation

This research, a new thrust-allocation algorithm based on penalty programming is developed to minimize the fuel consumption of offshore vessels/platforms with dynamic positioning system. The role of thrust allocation is to produce thruster commands satisfying required forces and moments for position-keeping, while fulfilling mechanical constraints of the control system. The developed thrust-allocation algorithm is mathematically formulated as an optimization problem for the given objects and constraints of a dynamic positioning system. Penalty programming can solve the optimization problems that have nonlinear object functions and constraints. The developed penalty-programming thrust-allocation method is implemented in the fully-coupled vessel–riser–mooring time-domain simulation code with dynamic positioning control. Its position-keeping and fuel-saving performance is evaluated by comparing with other conventional methods, such as pseudo-inverse, quadratic-programming, and genetic-algorithm methods. In this regard, the fully-coupled time-domain simulation method is applied to a turret-moored dynamic positioning assisted FPSO (floating production storage offloading). The optimal performance of the penalty programming in minimizing fuel consumption in both 100-year and 1-year storm conditions is demonstrated compared to pseudo-inverse and quadratic-programming methods.

Lifting Operation Simulation of a Dynamic-Position Crane Vessel

2013 ◽  
Author(s):  
Shangmao Ai ◽  
Liping Sun ◽  
Chuanyun Cheng
Keyword(s):  
Time Domain ◽  
Pid Control ◽  
Weak Coupling ◽  
Time Sequence ◽  
Irregular Waves ◽  
Dynamic Positioning ◽  
Wave Direction ◽  
Sea State ◽  
Control Equation ◽  
Made In

A time domain method, weakly coupling the block and crane vessel in time sequence, has been developed for lifting operation of the dynamic-position crane vessel. Restoring thrust is distributed by the dynamic positioning PID control system and directly acted on the crane vessel’s control equation as external force; the weak coupling simulation between the block and crane vessel is realized through the sling elastic deformation. Lifting operation simulation of a dynamic-position crane vessel in irregular waves shows that the posture of crane vessel relative to the wave direction in the lifting operation should be adjusted as soon as possible, and had better be made in ahead sea state to improve the security of the suspension stage.

Study on Dynamic Positioning Capacity Analysis Method Considering Wind Shielding Effect of Offshore Structure

2021 ◽  
pp. 1-11
Author(s):  
Jinhui He ◽  
Haibin Zhang ◽  
Renchuan Zhu
Keyword(s):  
Time Domain ◽  
Offshore Structures ◽  
Wind Load ◽  
New Method ◽  
Shielding Effect ◽  
Capacity Analysis ◽  
Dynamic Positioning ◽  
Time Domain Simulation ◽  
Environmental Loads ◽  
Load Calculation

Offshore structures floating at sea should use their dynamic positioning (DP) system to maintain position and heading against environmental loads, including wave loads, current loads, and wind loads. It is difficult to calculate environmental loads accurately and quickly, especially for wind loads due to the shielding effect of different parts on offshore structures. To improve the accuracy of wind load calculation, a new method considering shielding effect is proposed. With the new method, calculated wind force becomes much closer to wind tunnel test than the traditional method. As input data of DP capacity analysis, the environmental loads have critical impact on the design of DP system. A static method and a time-domain simulation method of DP capacity are also proposed, and a case study of drillship is carried out. The results of both static analysis and time-domain simulation of DP capacity show that the new wind load calculation method has improved the accuracy of environmental load calculation and DP capacity analysis. Introduction As the offshore oil and gas exploitation is going further into deep sea, offshore structures are to be used in harsh marine environments, including strong wind, current, and waves. Especially for wind, it can make great effect on the dynamic positioning (DP) system of offshore structures, which is designed to maintain position and heading. Once the DP system is not able to keep the offshore structures’ position and heading, it will cause an accident such as oil leakage and oil pollution in the ocean. Because of the wind shielding effect among all parts on offshore structures, such as deckhouse, derricks, cranes, pipe racks, the wind load is difficult to calculate accurately and quickly.

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