scholarly journals Maximum Power Extraction and Pitch Angle Control for Offshore Wind Turbine with Open-Loop Hydraulic Transmission

2019 â—½  
Author(s):  
Fan YaJun â—½  
Mu AnLe
Keyword(s):  
Wind Turbine â—½  
Pitch Angle â—½  
Open Loop â—½  
Maximum Power â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Power Extraction

scholarly journals Control of an Open-Loop Hydraulic Offshore Wind Turbine Using a Variable-Area Orifice

2015 â—½  
Author(s):  
Daniel Buhagiar â—½  
Tonio Sant â—½  
Marvin K. Bugeja
Keyword(s):  
Wind Turbine â—½  
Wind Turbines â—½  
Sea Water â—½  
Open Loop â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Electrical Transmission â—½  
Pelton Turbine â—½  
Hydroelectric Energy â—½  
Fixed Line

The viability of offshore wind turbines is presently affected by a number of technical issues pertaining to the gearbox and power electronic components. Current work is considering the possibility of replacing the generator, gearbox and electrical transmission with a hydraulic system. Efficiency of the hydraulic transmission is around 90% for the selected geometries, which is comparable to the 94% expected for conventional wind turbines. A rotor-driven pump pressurises seawater that is transmitted across a large pipeline to a centralised generator platform. Hydroelectric energy conversion takes place in Pelton turbine. However, unlike conventional hydro-energy plants, the head available at the nozzle entry is highly unsteady. Adequate active control at the nozzle is therefore crucial in maintaining a fixed line pressure and an optimum Pelton turbine operation at synchronous speed. This paper presents a novel control scheme that is based on the combination of proportional feedback control and feed forward compensation on a variable area nozzle. Transient domain simulation results are presented for a Pelton wheel supplied by sea water from an offshore wind turbine-driven pump across a 10 km pipeline.

Control Co-Design for Rotor Blades of Floating Offshore Wind Turbines

2020 â—½  
Author(s):  
Xianping Du â—½  
Laurent Burlion â—½  
Onur Bilgen
Keyword(s):  
Wind Turbine â—½  
Pitch Angle â—½  
Cone Angle â—½  
Bending Moment â—½  
Rotor Blades â—½  
Offshore Wind â—½  
Step Response â—½  
Offshore Wind Turbine â—½  
Blade Root â—½  
Floating Offshore Wind Turbines

Abstract This paper aims to demonstrate the application of control co-design methodology for the rotor blades of a floating offshore wind turbine. A 10 MW reference wind turbine model is utilized in the co-design framework. In this paper, the coupling effect between the system, defined by the pre-cone angle, and the controller, defined by pitch angle, is analyzed with a parametric study. The system parameters of the blade are identified by exciting the system with a step input, and by using the step response. The identified model is used to demonstrate the coupling effects of the structural parameters. The control co-design process is implemented to reduce the blade root bending moment by controlling the pitch angle as a function of the pre-cone angle. Utilizing the 10 MW reference model, the proposed control co-design method can reduce the blade root bending moment and attenuate transverse vibrations faster than the original design. Compared to a sequentially designed controller, the co-design demonstrated reduction of the blade root bending moment with similar attenuation time.

scholarly journals Control Algorithm for Parallel Connected Offshore Wind Turbine Generators

Energies â—½  
10.3390/en14154670 â—½  
2021 â—½  
Vol 14 (15) â—½  
pp. 4670
Author(s):  
Emir Omerdic â—½  
Jakub Osmic â—½  
Cathal O’Donnell â—½  
Edin Omerdic
Keyword(s):  
Wind Turbine â—½  
Wind Power â—½  
Wind Turbines â—½  
Control Algorithm â—½  
Low Frequency â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Power Extraction â—½  
Turbine Generators â—½  
Wind Turbine Generators

A control algorithm for Parallel Connected Offshore Wind Turbines with permanent magnet synchronous Generators (PCOWTG) is presented in this paper. The algorithm estimates the optimal collective speed of turbines based on the estimated mechanical power of wind turbines without direct measurement of wind speed. In the proposed topology of the wind farm, direct-drive Wind Turbine Generators (WTG) is connected to variable low-frequency AC Collection Grids (ACCG) without the use of individual power converters. The ACCG is connected to a variable low-frequency offshore AC transmission grid using a step-up transformer. In order to achieve optimum wind power extraction, the collective speed of the WTGs is controlled by a single onshore Back to Back converter (B2B). The voltage control system of the B2B converter adjusts voltage by keeping a constant Volt/Hz ratio, ensuring constant magnetic flux of electromagnetic devices regardless of changing system frequency. With the use of PI pitch compensators, wind power extraction for each wind turbine is limited within rated WTG power limits. Lack of load damping in offshore wind parks can result in oscillatory instability of PCOWTG. In this paper, damping torque is increased using P pitch controllers at each WTG that work in parallel with PI pitch compensators.

Experimental results of floating platform vibration control with mode change function using full-scale spar-type floating offshore wind turbine

Wind Engineering â—½  
2017 â—½  
Vol 42 (3) â—½  
pp. 230-242 â—½  
Author(s):  
Hiromu Kakuya â—½  
Takashi Shiraishi â—½  
Shigeo Yoshida â—½  
Tomoaki Utsunomiya â—½  
Iku Sato
Keyword(s):  
Vibration Control â—½  
Wind Turbine â—½  
Pitch Angle â—½  
Full Scale â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Floating Platform â—½  
Offshore Wind Turbines â—½  
Floating Offshore Wind Turbines â—½  
Blade Pitch Angle

Floating offshore wind turbines have great potential for harvesting renewable energy sources since offshore wind is stronger and more stable than onshore wind. The foundations of floating offshore wind turbines are not rigidly fixed and it leads to vibration of the floating platform pitch angle. This vibration is caused by fast blade pitch angle motions of variable speed control for controlling rotor speed at rated values. This study proposes a control method to address this vibration, floating platform vibration control. This method extracts a natural frequency component of the vibration from the floating platform pitch angle signal by a band pass filter and controls the blade pitch angle on the basis of proportional–derivative control. Its key characteristic is changing control modes in accordance with electrical power. Experiments using a full-scale spar-type floating offshore wind turbine were performed, and results show that the proposed floating platform vibration control can suppress the vibration of floating platform pitch angle.

Comparison of Model Tests and Coupled Simulations for a Semi-Submersible Floating Wind Turbine

2014 â—½  
Author(s):  
Fons Huijs â—½  
Erik-Jan de Ridder â—½  
Feike Savenije
Keyword(s):  
Wind Turbine â—½  
Pitch Angle â—½  
Model Tests â—½  
Torque Control â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Mooring System â—½  
High Quality â—½  
Design Requirements â—½  
Blade Pitch Angle

The GustoMSC Tri-Floater is a slender and robust three-column semi-submersible supporting an offshore wind turbine. Model tests were performed for a Tri-Floater equipped with an operational wind turbine and mooring system exposed to wind and waves in the offshore basin at MARIN. A high quality wind setup and special low Reynolds number blades were used, aiming at delivering the Froude scaled thrust. The base scope of experiments was performed with fixed blade pitch angle and generator speed. Some of the experiments were repeated with active blade pitch and generator torque control using a dedicated algorithm developed by ECN. The experiments covered typical operational and survival design conditions. Numerical simulations for the same wave and wind conditions were performed using ANSYS-AQWA coupled with PHATAS. The paper describes the setup and results of both the model tests and the simulations. From the comparison of the numerical and experimental results, it is concluded that coupled aero-hydro-servo-elastic simulations can be used to predict the response of the floating offshore wind turbine to a sufficiently accurate level for design purposes. Furthermore, it is shown that the Tri-Floater motion response is very favorable and that the nacelle accelerations, air gap and mooring loads comply with the design requirements.

The Influence of Sea Waves on Offshore Wind Turbine Aerodynamics

10.1115/1.4031005 â—½  
2015 â—½  
Vol 137 (5) â—½  
Author(s):  
A. AlSam â—½  
R. Szasz â—½  
J. Revstedt
Keyword(s):  
Wind Speed â—½  
Wind Turbine â—½  
Offshore Wind â—½  
Speed Ratio â—½  
Offshore Wind Turbine â—½  
Intensity Level â—½  
Sea Waves â—½  
Power Extraction â—½  
Wind Turbine Aerodynamics â—½  
Large Eddy

The impacts of swells on the atmospheric boundary layer (ABL) flows and by this on the standalone offshore wind turbine (WT) performance are investigated by using large eddy simulations (LES) and actuator-line techniques. At high swell to wind speed ratio, the swell-induced stress reduces the total wind stress resulting in higher wind velocity, less wind shear, and lower turbulence intensity level. These effects increase by increasing swell to wind speed ratio (C/U) and/or swell steepness. Moreover, for the same hub-height wind speed (Uhub), the presence of swells increases the turbine power extraction rate by about 3% and 8.4% for C/Uhub = 1.53 and 2.17, respectively.

Modeling Considerations for Testing Full-Scale Offshore Wind Turbine Nacelles With Hardware-in-the-Loop

2020 â—½  
Author(s):  
Kirk Heinold â—½  
Meghashyam Panyam â—½  
Amin Bibo
Keyword(s):  
Wind Turbine â—½  
Real Time â—½  
Open Loop â—½  
Full Scale â—½  
Offshore Wind â—½  
Offshore Wind Turbine â—½  
Hardware In The Loop â—½  
Time Simulation â—½  
Time Requirements â—½  
Torsional Frequency

Abstract When compared to open-loop configuration, full-scale wind turbine nacelle testing with Hardware-In-the-Loop (HIL) configuration allows for coupled electro-mechanical as well as full operational certification tests with the native nacelle controllers. This configuration requires a full turbine real-time simulation running in parallel to the nacelle under test. In this study, a baseline simulation model is used to investigate the nacelle fidelity necessary to capture dynamic characteristics of interest while meeting the real-time requirements. The same model is also utilized to understand the influence of different boundary conditions seen by the nacelle when mounted on a test bench without a rotor, tower, and platform. The results show that the torsional dynamics are mainly governed by the flexibility of the main shaft and the gearbox supports. It is also demonstrated that the abstraction of the nacelle leads to a torsional frequency shift and higher frequency content in component responses necessitating compensation techniques for proper implementation of HIL testing.

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