A New Loss of Field Detection Scheme for Synchronous Generators by Incorporating a Dynamic Equivalent Circuit Model

In this paper, a novel loss of field (LOF) detection method is proposed for synchronous generators by utilizing a dynamic equivalent circuit model (DECM). The DECM consists of an internal voltage source and an impedance connected in series, and the two parameters are estimated by measuring three-phase currents, three-phase phase-to-ground voltages, and the rotor speed of the generator. To achieve the proposed detection scheme, an LOF detection index (LFDI) is introduced to detect LOF. To validate the proposed method, an excitation system of the generator using the phase domain (PD) generator model is developed, allowing simulation of various LOF incidents, consistent with IEEE Std. C37.102. The simulated cases include various types of complete and partial LOF events, the stable power swing (SPS) events, and a LOF incidence during the SPS. These cases demonstrate that the proposed LOF detection scheme provides much faster and more secure LOF detection than conventional schemes. The proposed scheme is further validated by experiments in the lab, which demonstrates its feasibility in practical applications.