Fast predictive technique for reverse power detection in synchronous generator

Abstract

Reverse power relays are utilised to trip turbine generators to avoid prime mover damage and directional relay is most widely used as the main protection for these conditions. An intentional time delay is ordinarily utilised to overcome the possible maloperation of these relays. However, the intentional time delay to prevent maloperation is not an ideal solution. As this time delay increases the reverse power relay operation time, which means that the motoring action of the synchronous generator persist for a longer time, making the prime mover more vulnerable to active power drawn by the generator. This study proposes a new flux-based approach to detect reverse power condition in the synchronous generators. The proposed scheme uses the analysis of angular velocity and acceleration data that are calculated from the estimated magnetic flux at the machine stator terminals. The basic idea of the technique stems from the principle that the stator and rotor magnetic fluxes rotate together at synchronous speed and will not be affected by system disturbances for a short interval according to highly inductive characteristics of the synchronous machine. The main advantage of this predictive algorithm is its speed, security and sensitivity to detect the reverse power conditions.