2004 Fiscal Year Final Research Report Summary
Development of low-cost adjustable -speed generator systems suitable for renewable energy sources
| Project/Area Number |
14350140
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電力工学・電気機器工学
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| Research Institution | Ibaraki University |
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Principal Investigator |
OGUCHI Kuniomi Ibaraki University, the College of Engineering, Professor, 工学部, 教授 (50037868)
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| Co-Investigator(Kenkyū-buntansha) |
HOSHI Nobukazu Ibaraki University, the College of Engineering, Research associate, 工学部, 助手 (70292480)
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| Project Period (FY) |
2002 – 2004
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| Keywords | adjustable-speed generator / induction generator / secondary excitation / brushless / cascade connection / reluctance type / flux barrier |
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| Research Abstract |
Adjustable-speed wound-rotor induction generators are widely used for wind power generation, in which the secondary power is extracted through brushes and slip-rings and is controlled by an inverter. This secondary excitation system requires smaller ratings of the inverter than those of stator power control systems and it is economical. The brushes and slip-rings need periodical maintenance. Therefore, a big maintenance problem may be occur in near future because a large number of generatoras.
In our project, we have mainly studied brushless secondary excitation systems to solve the maintenance problem mentioned above. The major results of our research are as follows :
1.Brushless cascaded induction generator systems
A newly developed cascaded induction generator has been proposed in which the second induction generator has a six-phase winding and a 12-pulse diode rectifier. This system can give very economical solution of the maintenance problem and harmonic current pollution. However, a
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power factor correction may be needed to compensate the poor power factor characteristics. The proposed system is well suited for large power applications.
2.Brushless reluctance-type induction generators
A proto type of the doubly-fed reluctance-type induction generators was built and tested. This generator has a simple structure ; its rotor has no windings and only an iron core with flux barriers, and the stator has double three-phase windings with different pole-numbers. The experimental generator has good control characteristics except for the poor power factor.
3.A novel system of a wound-rotor induction generator
A slip power recover inverter in a conventional wound rotor induction generator system is connected in-parallel with the stator windings through three-phase transformers. We have developed a novel system in which the recovery inverter is connected directly in-series with the stator windings without using the transformers. The system steady-characteristics was examined with computer simulation and the good results were obtained. Transient characteristics will be studied in future for practical applications. Less
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