A New Synchronous Generator Out-of-Step Relay Scheme Part II Complete Version

In the complete version of the proposed generator out-of-step relay scheme, the equations solved by the powerplant computer are based on a two-machine system model which provides for the, effects of circuit resistance, constant uniform damping, and varying internal voltage of the protected generator. Transient saliency and variable damping effects are neglected. Mechanical shaft power is considered to remain constant throughout the transient period of a disturbance. The Direct Method of Lyapunov is used to determine the stability boundary for the two-machine system. The Lyanunov V-function employed in scheme computations is Mansour´s generalized V-function developed via the EMA (Energy Metric Algorithm). Tripping is initiated when the iteratively computed value of the generalized V-function during a system disturbance exceeds the iteratively computed value of b(t) or when it is determined that V>O. Nondelayed tripping prior to the time system torque angle reaches 180°is permitted provided the angle is favorable for breaker operation. If the angle is not favorable at the time instability is detected, tripping is delayed until the angle becomes favorable.