基于有限元方法的变压器外部短路工况电磁场仿真

发布时间：2018-03-22 02:32

本文选题：变压器　切入点：瞬态电磁场　出处：《东北电力大学》2017年硕士论文　论文类型：学位论文

【摘要】：变压器作为电力系统的关键元件,其安全运行对电力系统稳定具有重大意义。短路作为威胁变压器运行的主要问题,短路故障发生时变压器是受短路冲击影响最大的电气设备,面临着巨大的安全风险。因此,对短路问题进行研究有着重要的意义。本文介绍了大型电力变压器绕组短路计算的背景和意义,论述了变压器漏磁场、短路电动力等问题的国内外研究现状,然后结合广东电网公司一台开展短路试验的三相五柱式变压器结构参数,在ANSYS Maxwell软件中建立了变压器三维等比例仿真模型。仿真激励采用了场路耦合理论,模拟了变压器A相、B相高对中单相外部短路过程。不同于以往先通过电路仿真软件求得短路电流,后将短路电流作为有限元仿真激励加载的方式。场路耦合更符合变压器实际工作原理,因此仿真结果更具有可靠性。本文仿真变压器短路过程总时长为250ms,为了使仿真兼顾计算精度与效率,选定仿真时间步长为2.5ms。通过将仿真获得的短路电流与试验获取的短路电流进行对比,分析了瞬时短路电流峰值和对称短路电流有效值两个主要参数,验证了本文采用的场路耦合模型的可行性与正确性。同时,求解得到了非短路相绕组感应电势,铁芯磁密,漏磁场和绕组受力等参数。对试验未测量或不易测量的物理量,如非短路相绕组感应电势,铁芯磁密,漏磁场和绕组受力等参数进行了理论分析,均有较高的准确性。从而为进一步研究变压器外部短路问题,如短路过程中绕组稳定性问题、短路导致油流涌动等问题提供可靠的数据基础。
[Abstract]:As the key component of power system, the safe operation of transformer is of great significance to the stability of power system. Short circuit is the main problem threatening the operation of transformer, and the transformer is the most affected electrical equipment when short-circuit fault occurs. Therefore, it is of great significance to study the short-circuit problem. This paper introduces the background and significance of short-circuit calculation of large power transformer windings, and discusses the leakage magnetic field of transformer. Domestic and foreign research status of short circuit electric power and other problems, and then combined with the structural parameters of a three-phase five-column transformer with short circuit test carried out by Guangdong Power Grid Company. The three-dimension equal proportion simulation model of transformer is established in ANSYS Maxwell software, and the field circuit coupling theory is used in the simulation. The external short circuit process of phase A phase B phase high alignment is simulated, which is different from the previous short circuit current obtained by circuit simulation software. After the short circuit current is taken as the finite element simulation excitation loading mode, the field circuit coupling is more in line with the actual working principle of transformer. Therefore, the simulation results are more reliable. In this paper, the total time of the short-circuit process of the simulation transformer is 250ms. in order to make the simulation take into account the calculation accuracy and efficiency, The simulation time step is chosen to be 2.5ms.Through comparing the short-circuit current obtained by simulation with the short-circuit current obtained by experiment, two main parameters, the instantaneous short-circuit current peak value and the symmetric short-circuit current effective value, are analyzed. The feasibility and correctness of the field-circuit coupling model used in this paper are verified. At the same time, the parameters such as inductive potential of non-short-circuit phase winding, magnetic density of iron core, leakage magnetic field and force of winding are obtained. For example, induction potential of non-short-circuit phase winding, magnetic density of iron core, leakage magnetic field and force force of winding are theoretically analyzed, all of them have high accuracy. Thus, for further research on the problem of external short-circuit of transformer, such as the stability of winding in short-circuit process, Short-circuit causes oil flow surge and other problems to provide a reliable data base.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

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