应用有限元分析电力变压器绕组匝间短路的暂态特征

Application of finite element analysis to transient characteristics of interturn short circuit in power transformer windings

电力变压器做为变电站的关键核心设备,是电力系统安全稳定运行的基础,直接影响着供电可靠性。为了通过数值仿真方法重现电力变压器绕组单匝短路时的暂态过程,从而探讨验证故障机理,预测短路电动力,寻找与变压器绕组匝间短路密切相关的电气状态量,作者采用ANSYS Electronics Desktop有限元仿真软件建立与实际变压器一致的“场-路”耦合仿真模型,将变压器的空载损耗、空载电流、负载损耗及短路阻抗等性能参数的仿真值、解析计算值以及试验值做对比,在验证模型可靠准确的基础上,仿真研究变压器二次绕组在轴向与径向不同位置发生单匝短路时电磁参数、线匝受力和绕组损耗等暂态特征,并分析参数最大变化率及对外显示敏感程度,为变压器抗短路能力提升措施的研究提供理论依据,以及为配电变压器匝间绝缘在线监测、故障诊断与保护控制提供有利帮助。

Power transformer is a crucial equipment in power system. Its safe and stable operation directly affects the reliability of power supply. In order to reproduce the transient process of single turn short circuit of power transformer winding through numerical simulation method, so as to explore and verify the fault mechanism, predict the short-circuit electrodynamic force, and find the electrical state quantity closely related to the turn to turn short circuit of transformer winding, a “field circuit” coupling simulation model consistent with the actual transformer is established by using ANSYS electronics desktop finite element simulation software. The simulation values, analytical calculation values and test values of performance parameters such as no-load loss, no-load current, load loss and short-circuit impedance of transformer were compared. On the basis of verifying the reliability and accuracy of the model, the transient characteristics such as electromagnetic parameters, wire turn force and winding loss of transformer secondary winding in case of single turn short circuit at different axial and radial positions were simulated and studied. The maximum change rate of parameters and the sensitivity of external display were analyzed, which provides a theoretical basis for the improvement of transformer short-circuit resistance, and provides beneficial help for on-line monitoring, fault diagnosis and protection control of distribution transformer turn to turn insulation.