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Delegates are invited to meet and discuss with the poster presenters in this topic directly after the session 'Advanced rotor technologies' taking place on Tuesday, 11 March 2014 at 11:15-12:45. The meet-the-authors will take place in the poster area.

Masataka Oowada Hitachi, Japan
Masataka Oowada (1) F P Hiroshi Kato (1)
(1) Hitachi, Chiyoda-ku, Japan

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2014 and are published here unedited

Mr.Owada has been working in the wind industry for slmost 2 years.
He is currently Technical Councillor in the windturbine development team.
He studied mechanical engineering and nuclear engineering at Tokyo Institute of Technology in Japan.
After his studies he spent 36 years at Company Hitachi in various roles and has been involved in projects nuclear fuel design, robot arm for international space station, nuclear diagnostic system for cancer etc.
His job is focused on coaching for development of windturbine.


Concept of 5MW offshore downwind turbine


Hitachi has developed 2MW downwind turbines in 2005, which are suitable for Japanese mountainous lands and is selling more than 140 windturbines.
Based on this experience, Hitachi is developing 5MW offshore downwind turbine.
This paper shows the concept of 5MW offshore downwind turbine which is designed by system simulation,aerodynamic simulatoin and strength simulation.
And also include the feasibility of downwind turbine for larger than 5MW.


Hitachi has designed the 5MW offshore downwind turbine based on 2MW onshore downwind turbine. Concepts of 5MW offshore downwind turbine are high economical,high reliable and high adaptable for severe environment. To achieve high cost performance, we reduce the weight of main component by system simulation. To achieve high reliability we selected midium speed geared drivetrain by strength simulation. To achive high adaptablity for sever environment we evaluated nacelle and tower cooling system by aerodynamic simulation.

Main body of abstract

Reductoin of nacelle weight was achived by reducing load of main components such as blade, hub,gear and generator using independent pitch control and reduction of tower and fundation weight was achived by vibration control of rotor. Strength investigation of turbine rotary main shaft was done by modeling of full midium speed geared drivetrain and confirmed cumulative damage ratio less than 1. Study of passive cooling system for nacelle was done by aerodynamic simulation and designed the shape of nacelle. Simple configuration was achived because of downwind turbine.Temperatures in tower was analyzed by temperature prediction model which include wind speed and sunshine and confirmed slmost no change of annual amount of generation. When windturbine is getting larger in future,downwind turbine has merits. For example, evading interference between tower and blades brings reduction of blades weight because blades are located under the wind against the tower.Function of free yaw brings safty in blackout.


Concept of high cost performance ,high reliable and high adaptable for severe environment 5MW offshore downwind turbine has designed by system simulation, strength simulation and aerodynamic simulation based on 2MW onshore downwind turbine technology.Main components were procured and combination test has started at present.In 2014 5MW downwind turbine will construct in land and will start full scale test.

Learning objectives
Downwind turbine technology and experience provide the new knowledge in windturbine industry and development company.
And also shows the possibility for lager scale windturbine in future.