Experimental Investigation of Negative Damping Effects for a TLP Type Offshore Wind Turbine

2018 ◽  
Author(s):  
Masaaki Aoki ◽  
Sharath Srinivasamurthy ◽  
Kazuhiro Iijima ◽  
Naoyuki Hara ◽  
Tomoki Ikoma ◽  
...  
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Primary Control ◽  
Floating Platform ◽  
Scaled Model ◽  
Negative Damping ◽  
Motion Characteristics

Wind power generation has been paid much attention over the years as a countermeasure against global warming. Especially in recent years, researches and developments have also been made on Floating Offshore Wind Turbine (FOWT) in relatively deep offshore. Unlike Bottom-mounted Offshore Wind Turbine (BOWT), the motion characteristics of FOWT is complicated owing to coupled response of wind turbine and floating platform motions since the FOWT system is not fixed to the seabed. Due to these complexities, negative damping is one of the major problems reported for SPAR type FOWT moored by catenary chains. Negative Damping, in which the natural periodic motion is excited by blade pitch control employed for keeping the power generation constant, has to be addressed. In this paper, we discuss the negative damping of TLP type FOWT with a series of dedicated experiments. We manufactured a 1/100th-scale model TLP type FOWT model with a primary control system of the blade pitch angle for a geometrically scaled model of the 5MW wind turbine based on the NREL. At first, we formulated the mechanism for occurrence of Negative Damping and derived the conditions under which unstable fluctuations of the floating platform occurs using the motion equation. After that, we conducted scale model tank tests in wind alone and confirmed the phenomenon wherein the fluctuation of the floating platform does not converge. Finally, how dangerous such coupled motion of wind turbine and floating platform would be for real-scale FOWT is discussed.

scholarly journals Analysis of the Effect of a Series of Back Twist Blade Configurations for an Active Pitch-To-Stall Floating Offshore Wind Turbine

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Dawn Ward ◽  
Maurizio Collu ◽  
Joy Sumner
Keyword(s):  
Fatigue Life ◽  
Wind Turbine ◽  
Twist Angle ◽  
Bending Moment ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Power Performance ◽  
Floating Platform ◽  
Initiation Point ◽  
Negative Damping

Abstract For a turbine mounted on a floating platform, extreme induced loads can be increased by up to 1.6 times those experienced by a turbine situated on a fixed base. If these loads cannot be reduced, towers must be strengthened which will result in increased costs and weight. These tower loads would be additionally exasperated for a pitch-to-feather controlled turbine by a phenomenon generally referred to as “negative damping,” if it were not avoided. Preventing negative damping from occurring on a pitch-to-feather controlled floating platform negatively affects rotor speed control and regulated power performance. However, minimizing the blade bending moment response can result in a reduction in the tower fore-aft moment response, which can increase the tower life. A variable-speed, variable pitch-to-stall (VSVP-S) floating semi-submersible wind turbine, which does not suffer from the negative damping and hence provides a more regulated power output, is presented. This incorporates a back twist blade profile such that the blade twist, starting at the root, initially twists toward stall and, at some pre-determined “initiation” point, changes direction to twist back toward feather until the tip. Wind frequency weighting was applied to the tower axial fatigue life trends of different blade profiles and a preferred blade back twist profile was identified. This had a back twist angle of −3 deg and started at 87.5% along the blade length and achieved a 5.1% increase in the tower fatigue life.

Numerical Design of a Floating Offshore Wind Turbine Large Scale Model for Control Purposes

2021 ◽  
Author(s):  
Federico Taruffi ◽  
Simone Di Carlo ◽  
Sara Muggiasca ◽  
Alessandro Fontanella
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Large Scale ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Numerical Design ◽  
Blue Growth

Abstract This paper deals with the numerical design of a floating offshore wind turbine outdoor large-scale prototype based on the DTU 10MW. The objective of this work is to develop a numerical simulation environment for the design of an outdoor scaled prototype. The numerical model is realized coupling the preliminary designed Blue Growth Farm large-scale turbine model with a traditional floater, the OC3 spar buoy. The numerical model is used to evaluate the loads associated with the wind turbine when combined to a floating foundation, with the focus on the coupling between the dynamics of the control system and the one of the floating platform. In addition to this, also the consistency of loads on crucial turbine components is an interesting test bench for the evaluation of the dynamical effects and drives the final design of the physical model.

Conceptual Design of a Single-Point-Moored FOWT and Tank Test for Its Motion Characteristics

2013 ◽  
Author(s):  
K. Iijima ◽  
M. Kawai ◽  
Y. Nihei ◽  
M. Murai ◽  
T. Ikoma
Keyword(s):  
Wind Turbine ◽  
Transfer Functions ◽  
Single Point ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Loads ◽  
Scaled Model ◽  
Low Frequencies ◽  
Scale Ratio ◽  
Motion Characteristics

A new design concept of a semi-submersible type floating offshore wind turbine (FOWT) moored by a single-point mooring is proposed. The FOWT model adopting 5MW class wind turbine is designed. The motion characteristics of the FOWT are evaluated by a series of tank tests. To this end, a scaled model with a scale ratio 1/100 is fabricated. The scaled mode tests are performed under winds, waves, and combined winds and waves to check its fundamental feasibility. It is observed that the motion characteristics under wind and waves are acceptable in general, and the combination of the single point mooring and the down-wind type rotor is effective in terms of weathervane. It is also shown that the difference between the two transfer functions to wave loads, one with and the other without wind loads, is small except pitch response at low frequencies.

Designing Process and Motion Characteristics of Spar Type Offshore Wind Turbines

2013 ◽  
Author(s):  
Yasunori Nihei ◽  
Tomoki Ikoma ◽  
Minori Kozen ◽  
Fumiya Sato ◽  
Motohiko Murai ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Oil And Gas ◽  
Type Structure ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Offshore Wind Turbines ◽  
Motion Characteristics

In this paper, we will discuss about the designing process and the motion characteristics of the spar type offshore wind turbines. When considering a spar type structure for offshore wind turbines, it is important to take a lot of elements into consideration which have not yet been considered in the case of oil and gas platforms. In this research, we used the following standards to conduct our tests. The limit of the heel angle was 5 degrees when the wind turbines are generating in the rated state. When designing the substructure for this research we have decided to go with a substructure that operates in depth of 100m or more. Following the conditions above we have designed the spar type offshore wind turbine used for this research. In order to compare the simulated result we have created a scale model and performed tank tests under various conditions. Also we observed unexpected motion characteristics in certain mooring arrangement. So we will touch these subjects in this paper.

Experimental Study for SPAR Type Floating Offshore Wind Turbine With Blade-Pitch Control

2013 ◽  
Author(s):  
Toshiki Chujo ◽  
Yoshimasa Minami ◽  
Tadashi Nimura ◽  
Shigesuke Ishida
Keyword(s):  
Wind Turbine ◽  
Wind Farm ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Experimental Proof ◽  
Pitch Control ◽  
Model Experiments ◽  
North Eastern ◽  
North Eastern Part

The experimental proof of the floating wind turbine has been started off Goto Islands in Japan. Furthermore, the project of floating wind farm is afoot off Fukushima Prof. in north eastern part of Japan. It is essential for realization of the floating wind farm to comprehend its safety, electric generating property and motion in waves and wind. The scale model experiments are effective to catch the characteristic of floating wind turbines. Authors have mainly carried out scale model experiments with wind turbine models on SPAR buoy type floaters. The wind turbine models have blade-pitch control mechanism and authors focused attention on the effect of blade-pitch control on both the motion of floater and fluctuation of rotor speed. In this paper, the results of scale model experiments are discussed from the aspect of motion of floater and the effect of blade-pitch control.

scholarly journals Unsupervised Damage Detection for Offshore Jacket Wind Turbine Foundations Based on an Autoencoder Neural Network

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3333
Author(s):  
Maria del Cisne Feijóo ◽  
Yovana Zambrano ◽  
Yolanda Vidal ◽  
Christian Tutivén
Keyword(s):  
Neural Network ◽  
Wind Turbine ◽  
Environmental Conditions ◽  
Wind Farms ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Small Subset ◽  
Scaled Model ◽  
Vibration Data ◽  
Large Water

Structural health monitoring for offshore wind turbine foundations is paramount to the further development of offshore fixed wind farms. At present time there are a limited number of foundation designs, the jacket type being the preferred one in large water depths. In this work, a jacket-type foundation damage diagnosis strategy is stated. Normally, most or all the available data are of regular operation, thus methods that focus on the data leading to failures end up using only a small subset of the available data. Furthermore, when there is no historical precedent of a type of fault, those methods cannot be used. In addition, offshore wind turbines work under a wide variety of environmental conditions and regions of operation involving unknown input excitation given by the wind and waves. Taking into account the aforementioned difficulties, the stated strategy in this work is based on an autoencoder neural network model and its contribution is two-fold: (i) the proposed strategy is based only on healthy data, and (ii) it works under different operating and environmental conditions based only on the output vibration data gathered by accelerometer sensors. The proposed strategy has been tested through experimental laboratory tests on a scaled model.

Dynamic Response of a Spar-Type Floating Wind Turbine at Power Generation

2014 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Shigeo Yoshida ◽  
Soichiro Kiyoki ◽  
Iku Sato ◽  
Shigesuke Ishida
Keyword(s):  
Numerical Simulation ◽  
Power Generation ◽  
Dynamic Response ◽  
Wind Turbine ◽  
Prestressed Concrete ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Foundation ◽  
Mooring Dynamics ◽  
Nagasaki Prefecture

In this paper, dynamic response of a Floating Offshore Wind Turbine (FOWT) with spar-type floating foundation at power generation is presented. The FOWT mounts a 100kW wind turbine of down-wind type, with the rotor’s diameter of 22m and a hub-height of 23.3m. The floating foundation consists of PC-steel hybrid spar. The upper part is made of steel whereas the lower part made of prestressed concrete segments. The FOWT was installed at the site about 1km offshore from Kabashima Island, Goto city, Nagasaki prefecture on June 11th, 2012. Since then, the field measurement had been made until its removal in June 2013. In this paper, the dynamic behavior during the power generation is presented, where the comparison with the numerical simulation by aero-hydro-servo-mooring dynamics coupled program is made.

scholarly journals Large eddy simulations of offshore wind turbine wakes for two floating platform types

2020 ◽  
Vol 1452 ◽  
pp. 012034
Author(s):  
H M Johlas ◽  
L A Martínez-Tossas ◽  
M A Lackner ◽  
D P Schmidt ◽  
M J Churchfield
Keyword(s):  
Wind Turbine ◽  
Large Eddy Simulations ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Large Eddy
Sign in / Sign up

Export Citation Format

Share Document