转子匝间短路故障对大型汽轮发电机振动的影响机理

转子匝间短路是大型汽轮发电机时常发生的电气故障,会引起励磁电流增大、输出无功减小、机组振动加剧等不良现象。因不具备分支电流互感器的安装条件,基于定子不平衡电流总有效值的故障监测原理无法应用于大型汽轮发电机,而故障引起的机组振动为监测提供了一种新思路。为此,首先从分析转子匝间短路故障时定子和转子的稳态电流特征入手,全面考虑各种空间磁场的相互作用及转子热变形等实际因素,对故障后发电机的定子和转子振动特性进行了研究;通过对故障案例的调研验证了理论分析的正确性,并分析了影响振幅的关键因素。

Mechanism of Effects of Inter turn Short Circuits in Field Windings on Large Turbo-generator Vibration

As a common electrical fault of the large turbo-generator, the inter-turn short circuit in field windings leads to bad influence such as field current increase, output reactive power decrease, vibration aggravation, etc. Since most turbo-generators have no installation condition for a branch current transformer, application of the fault monitoring principle based on the stator unbalanced current RMS is limited. However, vibration caused by faults provides a new line of thought for monitoring. Therefore, proceeding from an analysis of the steady-state current characteristics of stator and rotor during inter-turn short circuit in field windings, comprehensive considerations is given to the interaction between various space magnetic fields and the thermal deformation of the rotor, while investigating the after-fault vibration characteristics of the stator and rotor of the generator. The correctness of the theoretical analysis is verified through research of fault cases, and the key factors influencing the amplitude of the vibration are analyzed.