End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windin...End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations.展开更多
Increasing size of wind turbine and deep water deployment have raised the issue of appropriate selection of the most suitable support structure to make offshore wind energy cost competitive.The paper presents an optim...Increasing size of wind turbine and deep water deployment have raised the issue of appropriate selection of the most suitable support structure to make offshore wind energy cost competitive.The paper presents an optimization methodology for decision making process of bottom mounted supports of offshore wind turbines （OWTs） through reasonable engineering attributes derivation.Mathematic models of support structures are reduced by the generalized single-degree-of-freedom theory with relatively fewer structural parameters.Soft-stiff design optimization based on dynamic properties of OWTs is performed for monopile and lattice supports with different wind turbines,water depth and hub height.Attributes of support structures,wind turbines and environment conditions are applied in the multi-criteria decision making method——TOPSIS for benchmarking of those options.The results illustrate the effectiveness of the proposed optimazation methodology combined with economical and environmental attributes together.展开更多
Hydro generators installed in Itaipu Binacional power plant with 824/737 MVA rated output power （50/60 Hz） belong to the largest ones in the world. Among many unique features, the generators are equipped with the la...Hydro generators installed in Itaipu Binacional power plant with 824/737 MVA rated output power （50/60 Hz） belong to the largest ones in the world. Among many unique features, the generators are equipped with the largest hydrodynamic thrust bearings ever built （external diameter 5,200 mm, axial load equals approximately 3,600 t）. This paper is an attempt to propose a new thrust bearing design with the use of the state-of-the-art technologies and simulation techniques that demonstrate a reduction of friction power losses generated by the thrust bearing. This paper is divided into two parts. Within the first one, the original thrust bearing design which was implemented in the generators is described. Related calculation results based on a TEHD （thermo-elasto-hydrodynamic） calculation software used by Alstom will be presented. A comparison between measurement results gathered in the 1980s is given. In the second part, a potential solution of a more beneficial bearing design is described. The proposed thrust bearing design modification is an implementation of Alstom＇s PolypadTM coating. This modern polymer （PEEK） coating material has already been used by Alstom in projects around the world for many years. This coating allows pushing the operating parameters limits toward higher temperatures and lower oil film thicknesses far beyond the limits known for the conventional bearing materials.展开更多
Let F be the underlying base field of characteristic p 〉 3 and denote by M the even part of the finite-dimensional simple modular Lie superalgebra M. In this paper, the generator sets of the Lie algebra M which will ...Let F be the underlying base field of characteristic p 〉 3 and denote by M the even part of the finite-dimensional simple modular Lie superalgebra M. In this paper, the generator sets of the Lie algebra M which will be heavily used to consider the derivation algebra Der（M） are given. Furthermore, the derivation algebra of M is determined by reducing derivations and a torus of M, i.e., Der（m）=ad（m） spanF{∏l ad （ξr＋1ξl）} spanF{adxi,ad（xiξ^v）∏ad（ξr＋1ξl）}. As a result, the derivation algebra of the even part of M does not equal the even part of the derivation superalgebra of M.展开更多
文摘End windings of generators are excited to vibrations due to electromagnetic forces which can cause severe damage and noise. To avoid this, it is important to predict the natural frequencies and modes of the end windings with finite elements. Due to the complex structure and unknown boundary conditions, the conventionally calculation of stator end windings has been very difficult and time consuming up to now. This paper describes the development of a full parameterized modeling tool, which allows a quick calculation of natural frequencies during the design phase of the generator. To keep the computing time low, it is important to find a way to get exact calculation results without detailed modeling of all pans. Additionally, special attention was paid to the active part, which has been replaced by spring-damper elements, and the determination of their stiffness via experimental modal analysis combined with finite element calculations.
基金Supported by the National Natural Science Foundation of China （No.51309209,51279186） and the National Basic Research Program of China （No.2011CB013704）.
文摘Increasing size of wind turbine and deep water deployment have raised the issue of appropriate selection of the most suitable support structure to make offshore wind energy cost competitive.The paper presents an optimization methodology for decision making process of bottom mounted supports of offshore wind turbines （OWTs） through reasonable engineering attributes derivation.Mathematic models of support structures are reduced by the generalized single-degree-of-freedom theory with relatively fewer structural parameters.Soft-stiff design optimization based on dynamic properties of OWTs is performed for monopile and lattice supports with different wind turbines,water depth and hub height.Attributes of support structures,wind turbines and environment conditions are applied in the multi-criteria decision making method——TOPSIS for benchmarking of those options.The results illustrate the effectiveness of the proposed optimazation methodology combined with economical and environmental attributes together.
文摘Hydro generators installed in Itaipu Binacional power plant with 824/737 MVA rated output power （50/60 Hz） belong to the largest ones in the world. Among many unique features, the generators are equipped with the largest hydrodynamic thrust bearings ever built （external diameter 5,200 mm, axial load equals approximately 3,600 t）. This paper is an attempt to propose a new thrust bearing design with the use of the state-of-the-art technologies and simulation techniques that demonstrate a reduction of friction power losses generated by the thrust bearing. This paper is divided into two parts. Within the first one, the original thrust bearing design which was implemented in the generators is described. Related calculation results based on a TEHD （thermo-elasto-hydrodynamic） calculation software used by Alstom will be presented. A comparison between measurement results gathered in the 1980s is given. In the second part, a potential solution of a more beneficial bearing design is described. The proposed thrust bearing design modification is an implementation of Alstom＇s PolypadTM coating. This modern polymer （PEEK） coating material has already been used by Alstom in projects around the world for many years. This coating allows pushing the operating parameters limits toward higher temperatures and lower oil film thicknesses far beyond the limits known for the conventional bearing materials.
基金supported by the National Natural Science Foundation of China(Nos.11171055,11471090)the Fundamental Research Funds for the Central University(No.14ZZ2221)+3 种基金the Jilin Provincial Natural Science Foundation of China(No.201115006)the Heilongjiang Provincial Natural Science Foundation of China(No.A201210)the Technology Program of Education Department of Heilongjiang Province(No.12531763)the Program for Young Teachers Scientific Research in Qiqihar University(No.2012K-M32)
文摘Let F be the underlying base field of characteristic p 〉 3 and denote by M the even part of the finite-dimensional simple modular Lie superalgebra M. In this paper, the generator sets of the Lie algebra M which will be heavily used to consider the derivation algebra Der（M） are given. Furthermore, the derivation algebra of M is determined by reducing derivations and a torus of M, i.e., Der（m）=ad（m） spanF{∏l ad （ξr＋1ξl）} spanF{adxi,ad（xiξ^v）∏ad（ξr＋1ξl）}. As a result, the derivation algebra of the even part of M does not equal the even part of the derivation superalgebra of M.
