干式空心电抗器匝间短路故障投切过电压有限元分析

Finite Element Analysis of Switching Overvoltage of Dry⁃type Air Core Reactor

针对电抗器常见的匝间短路故障,本文提出了一种干式空心电抗器匝间短路故障投切过电压有限元分析法。首先,建立电抗器三维有限元模型,通过计算电感矩阵验证了本模型的正确性;然后,基于场-路耦合法建立外电路模型,模拟电抗器投切的电压变化;最后,在有限元模型中设置短路点,进行短路电流、磁感应强度及电动力分析。研究表明:当干式空心电抗器发生匝间短路故障时,稳态电压下的短路电流会突然变大,短路点附近的磁感应强度变大并破坏原有的对称特性,短路点处电动力也会突然变大并且具有向外发散的趋势;在电抗器的投切瞬间,短路电流、磁感应强度及电动力的分布特性与稳态过程相似,但数值都会急剧增大,对电抗器稳定性产生更大的影响。

In view of common inter⁃turn short⁃circuit faults of reactors,a kind of finite element analysis method for the inter⁃turn short⁃circuit fault of the dry⁃type air core reactor is proposed in this paper.Firstly,the three⁃dimensional finite element model of reactor is established.The correctness of the model is verified by calculating the inductance matrix.Then,the external circuit model is established based on the field⁃path coupling method to simulate the voltage variation of the reactor switching.Finally,the short circuit point is set in the finite element model for the analysis of short⁃circuit current,magnetic induction and electrodynamic force.It is shown by the study that in case of inter⁃turn short circuit fault,the short⁃circuit current under steady⁃state voltage can suddenly increase,the magnetic induction intensity near the short⁃circuit point will become larger and the original symmetry will be destroyed,and the electric power at the short⁃circuit point will also be it suddenly becomes larger and has a tendency to diverge outward;At the instant of switching of the reactor,the distribution characteristics of short⁃circuit current,magnetic induction and electrodynamic force are similar to the steady⁃state process,but the value will increase sharply,which will have a greater impact on the stability of the reactor.