In order to achieve early diagnosis for inter-turn short circuit fault of field winding (ISFFW), electrical quantities under fault conditions, such as currents of stator and rotor winding, must be calculated accurately. An extended multi-loop math model for ISFFW is established, which considers the spatial harmonics of air-gap magnetic field, the unbalanced currents inside the phase windings, and changes of topological structure in excitation circuits due to rotor faults. It may accurately evaluate inductances of the field winding with the model under ISFFW and facilitate numerical simulation of all branch currents in stator and rotor windings during the whole fault transient. ISFFW experiments have been carried out on a 12 kW model synchronous generator with three non-salient pole-pairs. The experiment data of both transient and steady-state processes coincide well with the simulatiqn results obtained from the above math model, which verifies correctness of the math model and accuracy of the simulation program. Based on the simulation and experiment results, a summary is given on the steady-state characteristics of the faults, which may serve as the basis for the protection against ISFFW.%为实现励磁绕组匝间短路故障的早期诊断,需要准确计算故障电流等电气量.考虑到转子故障引起的气隙磁场的各种空间谐波、定子相绕组内部不平衡电流和励磁绕组电路拓扑结构的改变,建立了同步发电机励磁绕组匝间短路故障的扩充的多回路数学模型,并准确计算了与发生匝间短路故障的励磁绕组有关的电感参数,利用数值方法可对发电机励磁绕组匝间短路故障整个过渡过程中定子各分支及转子绕组电流等电气量进行数字仿真.在一台3对极隐极同步发电机上进行了转子匝间短路的实验研究,并利用文中的数学模型做了相应的仿真计算.故障过渡过程和稳态的实验结果均与仿真结果相吻合,验证了数学模型的正确性和仿真程序的准确性.通过仿真和实验归纳出这台电机励磁绕组匝间短路的稳态故障特征,可为转子匝间短路的检测与保护提供依据.
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