Flux linkage estimation based loss of excitation relay for synchronous generator

Abstract

Loss of excitation (LOE) event threatens both the generator and power system stability. Numerous approaches have been proposed for LOE detection, most of which use the impedance trajectory. Such methods may maloperate under system disturbances, especially power swings. This study presents a new approach for LOE detection by estimating the field flux linkage participation (FFLP) in the stator flux linkage. Intrinsically, this newly defined index mainly depends on the generator excitation system and thus highly reduces when an LOE takes place. The FFLP parameter can easily be calculated using stator voltage and current signals. All kinds of LOE events cannot be studied using most available simulation software. To cover all of them, utilising state variables, a generator model connected to a power system is implemented. Performed simulation studies demonstrate that the proposed strategy not only considerably decreases the LOE relay operation time, but also improves the LOE relay security against system disturbances. In addition, the proposed approach is experimentally evaluated on a 10 kVA synchronous generator.