转子绕组短路故障下不平衡电磁力计算方法

通过建立发电机有限元分析模型,得到故障下发电机内部磁力线走势、发电机气隙磁通密度的变化以及短路位置、短路匝数和励磁电流对转子不平衡电磁力的影响。对工程实际中常用的等效磁通法和磁势叠加法进行了分析比较,同时改进了现有的等效磁通计算方法。将两种方法不平衡电磁力的计算结果与有限元方法结果进行比较,指出了结果存在差异的原因。

Contrast of Calculation Method for Unbalanced Electromagnetic Force Under Rotor Inter-Turn Short Circuit Faults

The rotor inter-turn short circuit fault is one of the main electrical faults of turbo-generators. It can cause the unbalanced electromagnetic force to act on the rotor, leading to rotor vibration and even greatly affecting the security of the generator and power system. The accurate calculation of the electromagnetic force is significant for the stability of the generator and power system. By establishing the generator finite element model, the operation of the generator under a rotor winding short-circuit fault is simulated. The changes of magnetic field lines and air-gap field density are analyzed for the impacts of short position, short circuit number of turns and excitation current on the electromagnetic force. The equivalent magnetic flux method and the magnetomotive force superposition method are compared and come up with some improvements for the equivalent magnetic flux method. The calculation results of the unbalanced electromagnetic force by the two methods are compared with the results of the finite element method, and reasons for the difference are pointed out.