A new approach for generator loss of field (LOF) protection is proposed by estimating the field current based on the generator measurable parameters. The main idea of the proposed approach is that a significant difference will be created between the measured excitation and the estimated field currents during LOF occurrence. A differential index is introduced to monitor such difference and consequently to detect LOF failures. A detailed and realistic field circuit is considered for the generator by using the phase-domain model of the generator in the real-time digital simulator, while different types of LOF events can be simulated through such model as well. The obtained results show that the presented technique can detect various types of LOF events much faster than the conventional impedance-based scheme. Moreover, it exhibits more security than the conventional technique in the face of power system disturbances (e.g., stable power swing and out-of-step conditions).

中文翻译：

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一种基于电流的差分技术来检测同步发电机中的磁场损失

通过基于发电机可测量参数估计励磁电流，提出了一种用于发电机失磁 (LOF) 保护的新方法。所提出方法的主要思想是在 LOF 发生期间测量的励磁和估计的场电流之间将产生显着差异。引入了一个差分索引来监控这种差异，从而检测 LOF 故障。在实时数字模拟器中利用发电机的相域模型为发电机考虑了详细而真实的励磁回路，同时也可以通过该模型模拟不同类型的LOF事件。获得的结果表明，所提出的技术可以比传统的基于阻抗的方案更快地检测各种类型的 LOF 事件。而且，