Hitachi, Ltd.

Junji Tamura

Motoo Futami

Masaya Ichinose

Yasuo Ishimaru

Takeyuki Itabashi

Kazumasa Ide

Mitsugu Matsutake

Shinya Oohara

Kazumi Fujii

Hiroshi Kobayashi

A wind turbine-driven hydrogen production system controlling a power converter system such that the wind turbine stays in its operable range for a longer time and thus the hydrogen production system produces hydrogen for a longer time. The wind turbine-driven hydrogen production system varies an amount of electrical current supplied to an electrolytic hydrogen production system according to the rotational speed of the wind turbine to reduce variations in the rotational speed. Furthermore, the pitch angle of the wind turbine varies according to the speed. Thus, variations in the speed of the wind turbine can be reduced. A permanent-magnet generator is used as the electricity generator of the wind turbine to obtain a power supply at start-up. Alternatively, a power storage system used as assistive equipment at start-up is supplementarily added or only a power supply for the controllers is supplied from a system.

Hydrogen production system using wind turbine generator

When a welded joint is produced for joining metal components by applying a plurality of layers of deposited metal, the plurality of layers of deposited metal are provided in a groove of a weld preparation formed between the metal components to be joined in such a manner that each layer of deposited metal has a small thickness and a large width crosswise of the groove and the layers are arranged to be superposed one over another. During this process, a coarse metal structure formed when each underlying layer of deposited metal is provided is completely tempered and transformed into a fine metal structure by the heat generated when each overlying layer of deposited metal is provided. Thus the welded joint produced by this method shows an excellent performance in service.

Method for producing a welded joint

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Kitami, Japan

Junji Tamura