scholarly journals Controller Analysis in Real-Time Hybrid Model Testing of an Offshore Floating System

2018 ◽  
Author(s):  
Stefan A. Vilsen ◽  
Thomas Sauder ◽  
Martin Føre ◽  
Asgeir J. Sørensen
Keyword(s):  
Control System ◽  
Real Time ◽  
Hybrid Model ◽  
Low Frequency ◽  
Experimental Tests ◽  
Mooring System ◽  
Wave Excitation ◽  
Marine Structures ◽  
Wave Basin ◽  
Floating System

This paper presents an experimental study using Real-Time Hybrid Model (ReaTHM) testing of a moored floating cylindrical buoy, conducted in a wave basin. ReaTHM testing is a method for studying the dynamics of marine structures by partitioning the system into numerical and physical substructures that are then coupled in real-time using a control system. In this study, the floating cylinder buoy is modelled physically, and the mooring system modelled numerically. In this paper, the effect of selected controller parameters on the performance of the control system is studied, for both wave frequency and low-frequency ranges. The architecture/design of the control system is presented in the first part of the paper, while results from experimental tests with wave excitation on the physical substructure are presented in the second part of the paper.

Comparison of Real-Time Hybrid Model Testing of a Braceless Semi-Submersible Wind Turbine and Numerical Simulations

2017 ◽  
Author(s):  
Madjid Karimirad ◽  
Erin E. Bachynski ◽  
Petter Andreas Berthelsen ◽  
Harald Ormberg
Keyword(s):  
Wind Turbine ◽  
Real Time ◽  
Hybrid Model ◽  
Low Frequency ◽  
Ocean Basin ◽  
Model Testing ◽  
Second Order ◽  
Experimental Results ◽  
Scaled Model ◽  
Approximate Methods

In this paper, integrated analyses performed in SIMA are compared against experimental results obtained using real-time hybrid model testing (ReaTHM®) carried out in the ocean basin facilities of MARINTEK in October 2015. The experimental data is from a 1:30 scaled model of a semi-submersible wind turbine. Coupled aero-hydro-servo-elastic simulations are performed in MARINTEK’s SIMA software. The present work extends previous results from Berthelsen et al. [1] by including a blade element/momentum (BEM) model for the rotor forces in SIMA and comparing the coupled responses of the system to the experimental results. The previously presented hydrodynamic model is also further developed, and the importance of second order loads (and applicability of approximate methods for their calculations) is examined. Low-frequency hydrodynamic excitation and damping are seen to be important, but these loads include a combination of viscous and potential forces. For the selected concept, the second order potential flow forces have limited effects on the responses.

Low Frequency Micro-Vibration Active Isolation Control System Design and Experimental Research

2013 ◽  
Vol 482 ◽  
pp. 195-199 ◽  
Author(s):  
Shu Qing Li ◽  
Liang Liang Wang ◽  
Zhi Fei Tao
Keyword(s):  
Control System ◽  
Vibration Isolation ◽  
Active Vibration Control ◽  
Low Frequency ◽  
Experimental Tests ◽  
Seismic Exploration ◽  
Single Chip ◽  
Precision Equipment ◽  
Active Vibration ◽  
Micro Vibration

Whether in the aerospace, or seismic exploration, as well as high precision operation of all trades and professions, low-frequency interference directly influences the instrument monitoring and detection precision, resulting in insufficient accuracy of the implementing agencies. The passive vibration isolation method was used by most high accuracy equipment at present, the efficiency of isolation can only achieve 60%-70%, that will have influence to the extremely precision equipment certainly. In this paper an active vibration control system was realized by using single-chip microcomputer and the PID control algorithm. System simulation model was built and experimental tests had been conducted. The interference eliminated more than 80% for 3Hz and below,can effectively improve the precision equipment to work under the low frequency interference.The system provided an effective method to suppress the low frequency interference.

scholarly journals Real-Time Hybrid Model Testing of a Braceless Semi-Submersible Wind Turbine: Part II — Experimental Results

2016 ◽  
Author(s):  
Erin E. Bachynski ◽  
Maxime Thys ◽  
Thomas Sauder ◽  
Valentin Chabaud ◽  
Lars Ove Sæther
Keyword(s):  
Wind Turbine ◽  
Real Time ◽  
Hybrid Model ◽  
Low Frequency ◽  
Physical Structure ◽  
Ocean Basin ◽  
Test Method ◽  
Experimental Results ◽  
Irregular Waves ◽  
Aerodynamic Loads

Real-Time Hybrid Model (ReaTHM) tests of a braceless semi-submersible wind turbine were carried out at MARINTEK’s Ocean Basin in 2015. The tests sought to evaluate the performance of the floating wind turbine (FWT) structure in environmental conditions representative of the Northern North Sea. In order to do so, the tests employed a new hybrid testing method, wherein simulated aerodynamic loads were applied to the physical structure in the laboratory. The test method was found to work well, and is documented in [1]. The present work describes some of the experimental results. The test results showed a high level of repeatability, and permitted accurate investigation of the coupled responses of a FWT, including unique conditions such as blade pitch faults. For example, the influence of the wind turbine controller can be seen in decay tests in pitch and surge. In regular waves, aerodynamic loads due to constant wind had little influence on the structure motions (except for the mean offsets). Tests in irregular waves with and without turbulent wind are compared directly, and the influence of the wave-frequency motions on the aerodynamic damping of wind-induced low-frequency motions can be observed.

scholarly journals Advanced Control System for Grid-Connected SOFC Hybrid Plants: Experimental Verification in Cyber-Physical Mode

2019 ◽  
Author(s):  
Mario L. Ferrari ◽  
Iacopo Rossi ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Pid Control ◽  
Controller Design ◽  
Experimental Tests ◽  
Cell System ◽  
Hybrid Plant ◽  
Time Model ◽  
Point Data

Abstract This paper presents a Model Predictive Controller (MPC) operating an SOFC Gas Turbine hybrid plant at end-of-life performance condition. Its performance was assessed with experimental tests showing a comparison with a Proportional Integral Derivative (PID) control system. The hybrid system operates in grid-connected mode, i.e. at variable speed condition of the turbine. The control system faces a multivariable constrained problem, as it must operate the plant into safety conditions while pursuing its objectives. The goal is to test whether a linearized controller design for normal operating condition is able to govern a system which is affected by strong performance degradation. The control performance was demonstrated in a cyber-physical emulator test rig designed for experimental analyses on such hybrid systems. This laboratory facility is based on the coupling of a 100 kW recuperated microturbine with a fuel cell emulation system based on vessels for both anodic and cathodic sides. The components not physically present in the rig were studied with a real-time model running in parallel with the plant. Model output values were used as set-point data for obtaining in the rig (in real-time mode) the effect of the fuel cell system. The result comparison of the MPC tool against a PID control system was carried out considering several plant properties and the related constraints. Both systems succeeded in managing the plant, still the MPC performed better in terms of smoothing temperature gradient and peaks.

Structural Reliability Criteria for Control of Large-Scale Interconnected Marine Structures

2004 ◽  
Author(s):  
Per Ivar Barth Berntsen ◽  
Bernt J. Leira ◽  
Ole Morten Aamo ◽  
Asgeir J. So̸rensen
Keyword(s):  
Control System ◽  
Large Scale ◽  
Structural Reliability ◽  
Fish Farming ◽  
Current Control ◽  
Mooring System ◽  
Marine Structures ◽  
Mooring Cable ◽  
A Chain ◽  
Configuration Control

In this paper, we develop a model of a futuristic fish farming structure, and study problems related to interconnected marine structures and strategies for configuration control with focus on structural reliability. Configuration control refers to positioning of individual modules or the entire structure as a whole. The structure is a chain of surface vessels, moored to the seabed via a spread mooring system connected to the front vessel. In this paper we design a control system that: 1) Ensures limited loading of the mooring system in order to avoid mooring cable failure and;2) Ensures positive strain in the connectors between vessels in order to avoid buckling effects due to variations in for instance the current. Control actuation is by means of a thruster mounted on the first module. The performance of the control system is demonstrated by simulations.

Active coupling suppression and real-time control system design and implementation for three-axis electronic flight motion simulator

2017 ◽  
Vol 40 (4) ◽  
pp. 1352-1361
Author(s):  
Zhonghua Miao ◽  
Chenglei Wei ◽  
Zhiyuan Gao ◽  
Xuyong Wang
Keyword(s):  
Control System ◽  
Real Time ◽  
Hardware Implementation ◽  
Experimental Tests ◽  
Real Time Control ◽  
Control Software ◽  
Time Control ◽  
Motion Simulator ◽  
Suppression Method ◽  
Software And Hardware

Modelling of a three-axis electronic flight motion simulator with U-O-O structure is achieved in this paper, based on recursive Newton–Euler equations. To overcome the shortcomings of passive decoupling control methods, an active coupling torque suppression method is proposed using velocity internal feedback by analysing the influence of the coupling torque. Detailed control software and hardware implementation is given for the real-time control system. Experimental tests show the designed flight motion simulator system performs good dynamic and static performances.

Experimental and Numerical Study on Large Truncation of Deepwater Mooring Line

2009 ◽  
Author(s):  
Yihua Su ◽  
Jianmin Yang ◽  
Longfei Xiao ◽  
Gang Chen
Keyword(s):  
Dynamic Response ◽  
Water Depth ◽  
Numerical Study ◽  
Unit Length ◽  
Low Frequency ◽  
Model Tests ◽  
Mooring Line ◽  
Mooring System ◽  
Mooring Lines ◽  
Wave Basin

Modeling the deepwater mooring system in present available basin using standard Froude scaling at an acceptable scale presents new challenges. A prospective method is to truncate the full-depth mooring lines and find an equivalent truncated mooring system that can reproduce both static and dynamic response of the full-depth mooring system, but large truncation arise if the water depth where the deepwater platform located is very deep or the available water depth of the basin is shallow. A Cell-Truss Spar operated in 1500m water depth is calibrated in a wave basin with 4m water depth. Large truncation arises even though a small model scale 1:100 is chosen. A series of truncated mooring lines are designed and investigated through numerical simulations, single line model tests and coupled wave basin model tests. It is found that dynamic response of the truncated mooring line can be enlarged by using larger diameter and mass per unit length in air. Although the truncated mooring line with clump presents a “taut” shape, its dynamic characteristics is dominated by the geometry stiffness and it underestimates dynamic response of the full-depth mooring line, even induces high-frequency dynamic response. There are still two obstacles in realizing dynamic similarity for the largely truncated mooring system: lower mean value of the top tension of upstream mooring lines, and smaller low-frequency mooring-induced damping.

scholarly journals Advanced Control System for Grid-Connected SOFC Hybrid Plants: Experimental Verification in Cyber-Physical Mode

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mario L. Ferrari ◽  
Iacopo Rossi ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Pid Control ◽  
Controller Design ◽  
Experimental Tests ◽  
Cell System ◽  
Hybrid Plant ◽  
Time Model ◽  
Point Data

This paper presents a model predictive controller (MPC) operating a solid oxide fuel cell (SOFC) gas turbine hybrid plant at end-of-life performance condition. Its performance was assessed with experimental tests showing a comparison with a proportional integral derivative (PID) control system. The hybrid system (HS) operates in grid-connected mode, i.e., at variable speed condition of the turbine. The control system faces a multivariable constrained problem, as it must operate the plant into safety conditions while pursuing its objectives. The goal is to test whether a linearized controller design for normal operating condition is able to govern a system which is affected by strong performance degradation. The control performance was demonstrated in a cyber-physical emulator test rig designed for experimental analyses on such HSs. This laboratory facility is based on the coupling of a 100 kW recuperated microturbine with a fuel cell emulation system based on vessels for both anodic and cathodic sides. The components not physically present in the rig were studied with a real-time model running in parallel with the plant. Model output values were used as set-point data for obtaining in the rig (in real-time mode) the effect of the fuel cell system. The result comparison of the MPC tool against a PID control system was carried out considering several plant properties and the related constraints. Both systems succeeded in managing the plant, still the MPC performed better in terms of smoothing temperature gradient and peaks.

Reliability-Based Structural Optimization for Positioning of Marine Vessels

2006 ◽  
Author(s):  
Bernt J. Leira ◽  
Per I. B. Berntsen ◽  
Ole Morten Aamo
Keyword(s):  
Control System ◽  
Control Algorithm ◽  
Structural Reliability ◽  
Mooring System ◽  
Response Model ◽  
Marine Structures ◽  
Mooring Lines ◽  
Control Schemes ◽  
Marine Vessels

The present paper is concerned with floating marine structures that are kept in position by means of mooring lines in addition to a thruster system. Different options relevant for construction of automatic control schemes for the thruster system are first investigated based on a simplified response model. In particular, the role of structural reliability criteria applied to the mooring system is investigated. Subsequently, a more refined control algorithm based on such reliability criteria is introduced. The performance of this control system is demonstrated by numerical simulations.

Experimental Study of the Coupled Hydrodynamics of a DP Barge Operating Close to a FPSO

2012 ◽  
Author(s):  
Daniel P. Vieira ◽  
Eduardo A. Tannuri ◽  
João Luis B. Silva ◽  
Marcos D. Ferreira
Keyword(s):  
Experimental Study ◽  
Experimental Tests ◽  
Companion Paper ◽  
Small Scale ◽  
Dynamic Positioning ◽  
Mooring System ◽  
Hydrodynamic Coupling ◽  
Wave Basin ◽  
Scale Models ◽  
Industry Experience

The coupled hydrodynamic of a DP Barge operating close to a FPSO is evaluated. Experimental tests in a wave basin were performed to obtain the system dynamic behavior for several relative positions and environmental incidences. Two small scale models with factor 1:48 were tested in three different relative positions, five incidence angles and two irregular seas. The industry experience in operating barges was used to provide the insight to select these configurations. The DP Barge model was equipped with a dynamic positioning (DP) system, in order to keep its position relative to the FPSO. The FPSO model uses a scaled spread mooring system. Motions for DP Barge only were also obtained. Discussions are centered in reduction or amplification of DP Barge motions due the FPSO presence. Results are presented in terms of motions significant amplitude and RAO curves. A numerical model was evaluated and its results compared with the experiments. Some considerations, problems and conclusions about the operation were also obtained. These discussions complement the study presented by Vieira et al. (2011), which explored this operation numerically. A companion paper (Tannuri et al., 2012) will discuss the effects of the hydrodynamic coupling on the DP performance of the barge.

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