基于多回路－有限元耦合数学模型的同步发电机定子单相接地故障保护方案校验方法

同步发电机数学模型是进行故障暂态仿真，设计、校验保护方案的理论基础。文中将多回路方法与电磁场有限元计算相结合，建立了同步发电机的多回路一有限元耦合数学模型，其突出优点在于：可以同时计及定子绕组对地分布电容，磁路饱和、磁极形状、齿槽效应等因素，适用于同步发电机定子单相接地故障暂态分析及保护方案(尤其是三次谐波电压保护方案)校验。应用该数学模型完成了同步发电机定子单相接地故障暂态数字仿真，仿真与实验结果基本吻合，验证了该数学模型的准确性与有效性。进而提出了基于多回路一有限元耦合数学模型的同步发电机定子单相接地故障三次谐波电压保护方案校验方法。应用该方法对典型的定子单相接地稳态判据、暂态判据进行仿真校验，结果与实验基本吻合，表明该方法是正确可行的。

PROTECTION SCHEME CHECKOUT OF STATOR GROUND FAULT IN SYNCHRONOUS GENERATORS BASED ON MLM-FEM COUPLED MATHEMATICAL MODEL

Synchronous generator mathematical model is the theoretical foundation of performing fault transient simulation, developing and checking protection scheme. By combined Multi-Loop Method (MLM) with Finite Element Method (FEM), synchronous generator MLM-FEM coupled mathematical model is proposed, which possesses the distinguished capability to include accurately not only the distributed capacitances of the stator winding to the ground, but a variety of nonlinearities such as magnetic saturation, pole shape, and slot effect, and thus does be indeed suitable for transient analysis and protection scheme checkout, especially the third harmonic voltage based protection scheme checkout of stator ground fault in generators. The numerical simulation of this type of fault is completed by using the MLM-FEM coupled mathematical model, along with the related experiments. The simulation result has a well agreement with the experiment result, verifying the validity and effectiveness of the synchronous generator MLM-FEM coupled model proposed in this submission. Furthermore, a checkout method for the third harmonic voltage based protection scheme of stator ground fault in generators is presented based on the verified MLM-FEM coupled model. The checkout instance of the typical third harmonic voltage based protection scheme demonstrates explicitly that the checkout method is valid and practicable.