A Novel Approach to Detect the Synchronous Generator Loss of Excitation

The loss-of-excitation (LOE) event threatens the generator and power system stability. Several methods have been proposed for LOE detection, most of which are based on the impedance trajectory. These approaches may not be able to distinguish between LOE and the stable generator swing (SGS). Thus, allocating an operation time delay is usually used to overcome the LOE relay misoperation due to SGS. This paper presents a new approach for the LOE relay. The proposed strategy exploits a combined scheme based on the derivative of the terminal voltage and the output reactive power of the generator. Comprehensive simulation studies are accomplished for various generator conditions and system disturbances to determine the relay setting and to evaluate its performance. The performed studies demonstrate that the proposed strategy enhances security and operation time of the LOE relay, compared with some existing methods.