A New Hybrid Model for Electromechanical Characteristic Analysis under SISC in Synchronous Generators

Abstract

This paper proposes a novel hybrid model for analyzing the electromechanical characteristics under stator interturn short-circuit (SISC) fault in synchronous generators. The hybrid of the model lies in that it considers the static air-gap eccentricity and SISC at the same time. Different from other studies, the proposed model can manage not only the impact of the short-circuit degree, but also the influence of the short-circuit positions on the magnetic flux density (MFD), which is the basis to analyze electromechanical characteristics. The phase current and the electromagnetic torque (EMT) are selected in this paper as the representative of the electrical parameter and the mechanical parameter, respectively. Two-dimensional finite-element analysis and experimental studies confirm the validation of the proposed model. The model employs two primary factors, i.e., the short-circuit turn number nm and the position angle αsm , to reflect the short-circuit degree and the short-circuit position, respectively. By feeding these two factors as well as the detailed parameters of the generator into the model, the electromechanical feature data such as the phase current and EMT can be quickly assessed, and the developing tendency of the key MFD-based parameters can be conveniently predicted.