Mikio Kakiuchi
Toshiba
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Publication
Featured researches published by Mikio Kakiuchi.
IEEE Transactions on Industry Applications | 2009
Masafumi Fujita; Yasuo Kabata; Tadashi Tokumasu; Ken Nagakura; Mikio Kakiuchi; Susumu Nagano
Stator coils transposed by 540deg are widely used as one of the solutions to reduce the circulating current loss in the coil strands of turbine generators. However, the difference of the leakage fluxes in the two coil end parts, which is possibly caused by the coil end length deviation, the winding pitch, and the presence of the connection rings, may induce unbalanced voltage in the stator coil strands, which increase circulating current loss even in the transposition coils. This paper describes the mechanism and the analysis results of the circulating current increase in the coil strands due to the coil end flux difference. Then, some new schemes to reduce the circulating current loss are proposed and discussed.
international electric machines and drives conference | 2005
Masafumi Fujita; Yasuo Kabata; Tadashi Tokumasu; Mikio Kakiuchi; Hidekazu Shiomi; Susumu Nagano
On the air-cooled turbine generators, windage loss is the substantial factor of generator losses. One solution for the windage loss reduction is to minimize the amount of coolant air with the multiple-pitched ventilation ducts in the stator core. However, non-uniform duct distribution leads to the circulating currents in the stator bar strands which increase coil losses and cause significant distribution of strand loss. This paper presents circulating currents due to multiple-pitched ventilation ducts and some schemes to reduce the circulating current loss, such as new transposition systems of coil strand
international conference on electrical machines and systems | 2009
Masafumi Fujita; Takashi Ueda; Tadashi Tokumasu; Ken Nagakura; Mikio Kakiuchi; Toru Otaka
In the stator core end region of the large capacity turbine generators, the leakage magnetic flux induces eddy current loss in the metal structures. In this paper, the results of three-dimensional electromagnetic field analyses of the stator end structures are described. It is demonstrated that the eddy current loss dependency on the power factor can be explained with the phasor diagrams on the magnetic flux. Then the relationship between the end structure and the current source is discussed.
IEEE Transactions on Energy Conversion | 2012
Daisuke Hiramatsu; Tadashi Tokumasu; Masafumi Fujita; Mikio Kakiuchi; Toru Otaka; Osamu Sato; Ken Nagasaka
This paper presents a new method for estimation of rotor surface losses in small-to-medium capacity synchronous machines. In this study, the authors have proposed a method for estimating the slot ripple losses induced on the rotor surface. Also, we compared the damper systems using the finite-element method and verified the results by the measured data.
international conference on electrical machines and systems | 2009
Ken Nagakura; Toru Otaka; Mikio Kakiuchi; Yuichiro Gunji; Shinya Nakayama; Daisuke Murata; Yasuo Kabata; Hiroshi Hatano
Water-cooled stator-winding generators are widely used for large capacity turbine generators of thermal power plant. However, simpler stator cooling system is preferred considering easy operation and maintenance and lower cost. Hydrogen indirectly cooled generator is one of the solution with expansion its capacity. TOSHIBA has developed, manufactured and tested 670MVA hydrogen indirectly cooled generator.
2006 IEEE Power Engineering Society General Meeting | 2006
Daisuke Hiramatsu; Mikio Kakiuchi; Ken Nagakura; Yoichi Uemura; K. Koyanagi; Kaiichirou Hirayama; Susumu Nagano; R. Nagura; Ken Nagasaka
This paper describes the analytical study on generator load rejection characteristic using the advanced equivalent circuit model. The authors have studied the synchronous machine equivalent circuit model and transient phenomena, by simulation with the electromagnetic transients program (ATP-EMTP), and compared the results with the experimental data
IEEE Power Engineering Society General Meeting, 2005 | 2005
Susumu Nagano; Daisuke Hiramatsu; Kaiichirou Hirayama; Yoichi Uemura; Mikio Kakiuchi; K. Koyanagi; T. Satoh; Ken Nagasaka
This paper describes the effects of field mutual leakage reactance in rotor circuit (Canay reactance) on analysis of generator transient and dynamic behavior. The authors derived a detailed equivalent circuit model for generator, and analyzed sudden short circuit out-of-phase synchronization load rejection and sudden load application phenomena of the generator by simulations using the electromagnetic transients program (ATP-EMTP). Then, they compared the obtained results with the experimental data to verify the validity of the proposed equivalent circuit. In addition to these analyses, the influence of field mutual leakage reactance on analysis of power system dynamic stability was investigated.
power and energy society general meeting | 2012
Daisuke Hiramatsu; Yoichi Uemura; Masashi Kobayashi; Mikio Kakiuchi; Ken Nagakura; Toru Otaka; Ken Nagasaka
This paper presents the influence of reactance saturation in transient and stability phenomena for cylindrical synchronous machine. For this purpose the authors have examined various equivalent circuit models using electromagnetic transients program (EMTP-ATP).
power and energy society general meeting | 2008
Daisuke Hiramatsu; Yoichi Uemura; Jyunji Okumoto; Shinji Uemoto; Takehiko Imai; Mikio Kakiuchi; Ken Nagakura; Toru Otaka; Masafumi Fujita; Ken Nagasaka
This paper describes a study on equivalent circuit model in a large synchronous machine. In this study, the authors studied the quadrature axis transient reactance xpsilaq, not only the influence of the operational impedance , but also the difference of transient and dynamic characteristics using finite element method (FEM) and EMTP.
IEEE Power Engineering Society General Meeting, 2004. | 2004
Daisuke Hiramatsu; K. Koyanagi; Kaiichirou Hirayama; Yoichi Uemura; Mikio Kakiuchi; T. Satoh; Ken Nagasaka
This paper describes the effect of field mutual leakage reactance in rotor circuit (Canay reactance) on analysis of small or medium capacity generator transient and dynamic behavior .The authors proposed the decision method of field mutual leakage reactance, and analyzed sudden short circuit and the power system dynamic stability characteristics affected by the rotor mutual leakage reactance