POLE-SLIP PROTECTION SYSTEM AND METHOD FOR SYNCHRONOUS MACHINES

摘要

A method of protecting a synchronous machine (10) connected to an electricity network (12) against pole-slip comprises the steps of continuously monitoring a power transfer angle (d) between an electromotive force (EMF) of the machine and a reference voltage Vref. In the event of a fault (24) on the electricity network which may result in pole-slip of the machine (10), deriving a representation of power transfer (P) relating to the machine against the power transfer angle (d) utilizing data relating to a value of a current or a voltage measured on a terminal (26) of the machine before the fault has occurred and computed data relating to an expected future value of a current or voltage on the terminal (26), after the fault has occurred. The method then utilizes the representation and a stability criterion to predict whether the machine (10) may become unstable and if instability is predicted, causes the machine (10) to be disconnected at 32 or 34 from the electricity network (12).