两种减少高温超导风机交流损耗的结构优化方法
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摘要
超导线圈的制冷问题是高温超导(HTS)风力发电机研究中的一个重点,尤其是在使用接触式制冷的超导电机中,现有制冷机的制冷功率普遍较低,这就要求超导线圈的交流损耗不能太大。在超导风力发电机中,为了减少交流损耗,通常将超导线圈放置在转子中作为励磁线圈使用。在定子齿部材料为铁磁材料的旋转电机中,气隙磁场会发生畸变,转子旋转时超导线圈处会出现交变磁场,产生交流损耗。通过有限元软件仿真,以使用接触式制冷系统的2.5MW高温超导风力发电机为研究对象,证明使用铁磁材料的定子齿部结构是造成超导线圈处交变磁场和交流损耗的主要原因。采用均一化模型计算交流损耗,提出两种减小交变磁场和交流损耗的结构优化方法,即定子齿部采用非磁性材料和在气隙处增加磁屏蔽层。
The cooling problem for the superconducting coil is the focus of research in high temperature superconducting( HTS) wind generator,especially in the generator which uses contact refrigeration. Because the low cooling power of the available refrigerator,the AC loss of superconducting coils can't be too large. In order to reduce the AC loss,the superconducting coil is placed in the rotor as a excitation coil. In the generator whose stator teeth use ferromagnetic material,there will be a magnetic flux distortion in the air-gap,leading to an alternative magnetic field and AC loss in the superconducting coil when the rotor rotates.Through the finite element simulation,a 2. 5MW HTS wind generator which used contact refrigeration system was focused on to prove that the stator teeth using ferromagnetic material were the main reason of alternative magnetic field and AC loss. The homogenization model was used to calculate the AC loss. Two structure optimized methods to reduce the alternative magnetic field and AC loss were proposed including using non-ferromagnetic material in the stator teeth and using copper shield in the air.
The cooling problem for the superconducting coil is the focus of research in high temperature superconducting( HTS) wind generator,especially in the generator which uses contact refrigeration. Because the low cooling power of the available refrigerator,the AC loss of superconducting coils can't be too large. In order to reduce the AC loss,the superconducting coil is placed in the rotor as a excitation coil. In the generator whose stator teeth use ferromagnetic material,there will be a magnetic flux distortion in the air-gap,leading to an alternative magnetic field and AC loss in the superconducting coil when the rotor rotates.Through the finite element simulation,a 2. 5MW HTS wind generator which used contact refrigeration system was focused on to prove that the stator teeth using ferromagnetic material were the main reason of alternative magnetic field and AC loss. The homogenization model was used to calculate the AC loss. Two structure optimized methods to reduce the alternative magnetic field and AC loss were proposed including using non-ferromagnetic material in the stator teeth and using copper shield in the air.
引文
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[2]Lewis C,Muller J.A direct drive wind turbine HTS Generator[C]//Power Engineering Society General Meeting.IEEE Xplore,2007:1-8.
[3]Jensen B B,Mijatovic N,Abrahamsen A B.Development of superconducting wind turbine generators[J].Journal of Renewable&Sustainable Energy,2013,5(2):387-401.
[4]Sanz S,Arlaban T,Manzanas R,et al.Superconducting light generator for large offshore wind turbines[C]//Journal of Physics Conference Series,2014:032040.
[5]Hwang Y J,Ahn M C,Lee T S,et al.Experimental study of the effects of alternating fields on HTS coils according to the winding insulation conditions[J].Superconductor Science&Technology,2013,26(8):2391-2407.
[6]Liu D,Polinder H,Magnusson N,et al.Ripple field AC losses in 10 MW wind turbine generators with a Mg B2superconducting field winding[J].IEEE Transactions on Applied Superconductivity,2016,26(3):1-1.
[7]Zermeno V M R,Abrahamsen A B,Mijatovic N,et al.Calculation of alternating current losses in stacks and coils made of second generation high temperature superconducting tapes for large scale applications[J].Journal of Applied Physics,2013,114(17):173901-173901-9.
[8]Hong Z,Campbell A M,Coombs T A.Numerical solution of critical state in superconductivity by finite element software[J].Superconductor Science&Technology,2008,19(12):1246-1252.
[9]Kim H M,Yoon Y S,Kwon Y K,et al.Design of damper to protect the field coil of an HTS synchronous motor[J].IEEE Transactions on Applied Superconductivity,2009,19(3):1683-1686.