【作者】 康雅华；

【导师】 白保东；

【作者基本信息】 沈阳工业大学 ， 电机与电器， 2014， 博士

【摘要】 大容量发电机和联络变压器大都用在大型电站、核电站或重要线路的输送上，所以运行可靠性至关重要。随着变压器容量增大，运输条件及现场安装要求等条件限制原因，出现了铁心解体、压轭等特殊结构大型变压器，与一般变压器比较，该类变压器铁心内部磁场不平衡。准确计算这类变压器铁心磁场、空载损耗和结构件的杂散损耗从而避免局部过热，对于提高变压器运行的可靠性和保证电力系统的安全运行具有十分重要的意义。而随着容量和电压等级的提高，变压器的磁场和杂散损耗分布的不合理性而造成的局部损耗集中，是局部过热和运行故障的直接原因。因此，为保证大容量磁不平衡变压器的安全运行，提高运行可靠性，必须进行此类变压器产品性能、参数的深入研究，以提高大型磁不平衡电力变压器磁场、损耗的计算精度，来准确确定发热源，以避免铁心及结构件等局部过热的发生。为了准确计算变压器叠片铁心硅钢片中磁场、空载损耗及激磁电流的大小和分布，本文提出了考虑铁磁材料非线性各向异性电磁特性的瞬态场路耦合的计算方法。是在传统瞬态场路耦合计算方法的基础上做了改进，推导了在瞬态场路耦合下分别考虑铁磁材料的非线性各向同性和非线性各向异性电磁特性的二维、三维有限元离散化公式，其中有限元离散化得出的非线性代数方程组采用牛顿-拉夫逊法求解，牛顿-拉夫逊法是求解非线性代数方程组的常用方法，应用该方法能够大大提高大型电力变压器磁场及损耗的计算精度。编制了考虑硅钢片叠片铁心非线性各向异性电磁特性的二维、三维瞬态场路耦合的计算程序，为了验证所提出的计算方法和所编制的计算机程序的正确性，本文分别采用了TEAM问题10和TEAM问题21（P21-B模型、P21C-M1和P21C-M1的补充模型）进行了非线性各向同性和非线性各向异性自编程序的校验，并将该方法应用于大容量三相五柱铁心解体结构变压器和铁轭压缩结构变压器铁心瞬态磁场的仿真计算，分析了三相五柱铁心解体结构与三相五柱铁心非解体结构变压器铁心瞬态磁场、空载损耗密度分布和激磁电流在随时间变化的区别和大小，对铁轭压缩结构变压器分别选取了四种不同铁轭最大片宽模型进行了铁轭中磁通密度及空载损耗的计算分析。并将以上两种铁心特殊结构变压器空载损耗、激磁电流等计算结果与试验结果进行对比分析，验证了所编程序的有效性和正确性。在线圈结构复杂的大型自耦电力变压器三维漏磁场和结构件杂散损耗的计算中，由于线圈分别采用了两柱并联且旁柱激磁、调压结构和单相三柱并联结构，对于这种线圈特殊结构变压器，采用传统方法（电路方法）计算线圈电流分配时，因其无法考虑磁路的不平衡，因此计算误差较大。本文针对这一问题，采取了三维场路耦合方法来计算线圈的电流分配，通过准确的电流计算值来提高变压器结构件损耗和线圈短路阻抗等计算精度。并分别对大容量单相双柱并联且旁柱激磁调压结构的变压器和单相三柱并联结构变压器进行线圈电流、阻抗和结构件涡流损耗的仿真计算。其中对单相三柱并联结构变压器分析了油箱不同屏蔽方案时对线圈电流分配及阻抗的影响。采用小线圈法对线圈漏磁及结构件表面漏磁进行了测量及误差分析，最后将漏磁、损耗的计算结果与试验结果进行了对比分析，验证了本文研究成果的正确性和有效性。为以后更大容量特高压变压器提供设计依据。更多还原

【Abstract】 It is very important to steadily operate for special structure large capacity generatortransformer and system-interconnection transformer which are used in large power stations,nuclear power plants or important transmission. Special structural large power transformersuch as transformer of disintegration structure and compression iron yoke structure emerge asincreasing capacity of transformer and restriction of transportation condition and siteinstallation. compared with general transformer, unbalanced magnetic field is established inthese transformers inner. It has great significance for improving the reliability of transformeroperation and ensuring the safety operation of power system to accurately calculate magneticfield of core, no-load loss and stray losses of a large power transformer and avoid the localoverheating. The local losses concentration is the direct cause of local overheating andoperational failure caused by the inconsequence of magnetic leakage field and stray lossdistribution with increasing of capacity and voltage. Therefore, to improve the calculationprecision of magnetic field and loss of large magnetic-imbalance power transformer and avoidlocal overheat, the performance and parameters of the special structure transformer must bestudied deeply to ensure the safe operation of special structure large capacity transformer andimprove the reliability of operation and determine the location of the heating source avoidinglocal heating of the structural parts.In order to analyze accurately the size and distribution of no-load loss and excitingcurrent and the magnetic field in the transformer core silicon steel laminations, a transientcalculation method coupling field-circuit is presented in this thesis considering nonlinearanisotropic magnetic properties of ferromagnetic materials. Transient calculation methodcoupling field-circuit has been improved compare with the traditional calculation method. Theexpressions of FE discretization are deduced in2D and3D transient eddy current fieldcoupling field-circuit considering the electromagnetic characteristics of different materialssuch as anisotropy and isotropy and nonlinearity respectively. Nonlinear algebraic equationsare solved by Newton-Raphson method which is common method to solve these equations,calculation accuracy of magnetic field and losses of large power transformers can be improvedgreatly using this method.A calculation program is developed considering2D and3D transient field-circuit coupling considering magnetic properties of laminated core such as nonlinear and anisotropic.The supplementary model of TEAM problem10and TEAM problem21(P21Bmodel,P21C-M1model and supplementary model of P21C-M1) are used as a example to verify thevalidity of proposed method and the computer program including nonlinear and anisotropyand isotropy, and the method is also applied to calculate the transient magnetic field in thelarge-capacity three-phase five-column transformer of disintegration structure and thetransformer of compression iron yoke structure, the transient magnetic field of transformercore, distribution of lossdensity of no-load and the difference and size of exciting currentchange with time are analyzed. Magnetic flux density and no-load loss of four different kindsof maximum sheet width model is calculated and analyzed aiming at compression iron yokestructure transformer. The validity and the correctness of the program code is verifiedcompared with the experimental results of two different kinds of power transformer with thespecial core structure.The calculation error of the coil current is larger using a conventional method when3Dleakage magnetic field and structural parts stray losses of large complex auto-powertransformer is calculated because the special structure is applied to the coil such as twocolumn parallel structure, side column excitation, voltage regulation and single-phase threecolumn parallel. A great calculation error is obtained when current of coil is calculated usingtraditional method (circuit method). To solve this problem, a3D field-circuit coupling methodis applied to calculate the coil current distribution in order to improve the calculation accuracyof structure losses and short-circuit impedance using accurate current. Coil current, impedanceand structural eddy current losses of transformers of large-capacity single-phase two-pillar ofexciting and a single three-column-pillar structure is simulated respectively.更多还原