A Comprehensive EMF Behind Transient Reactance (EBTR) Model for Power System Stability Study

EMF behind transient reactance (EBTR) model of a synchronous generator has widely been used in the studies of power system stability. The damping in the quadrature axis of a synchronous machine is normally represented by a single time constant equivalent circuit. However, the presence of field in addition to the damper circuit in the direct axis of the machine makes modelling difficult in the direct axis based on the emf behind transient reactance. As a result approximate representations are normally employed. The models based on appropriate representations do not produce accurate results. In this paper, an accurate comprehensive model for the direct axis is presented. The development emerges from the detailed representation of the machine with fluxes as the state variable. The emfs behind field and d-axis damper transient reactances are considered in the model. The validity of the model is tested by comparison with the responses obtained from a detailed model.