Patent ID: 9093839
Filing Date: 2015-07-28
Classification: H02H,H02P

Abstract:
1. A method of protecting a synchronous machine arrangement connected to an electricity network against pole-slip, the method comprising the steps of: continuously monitoring a first variable parameter relating to the machine arrangement in the form of power transfer angle between an electromotive force (EMF) with reference to a reference voltage (Vref); in the event of a fault on the electricity network which may result in pole-slip of the machine arrangement, deriving a representation of a second parameter relating to the machine arrangement in the form of power transfer P against the first parameter utilizing data relating to a value of a third parameter relating to the machine arrangement in the form of at least one of actual voltage and current measured on a terminal of the machine arrangement before the fault has occurred and computed data relating to an expected future value of a fourth parameter relating to the machine arrangement in the form of at least one of voltage and current on the terminal of the machine arrangement after the fault has occurred; utilizing the representation and a stability criterion to predict whether the machine arrangement may become unstable; and if instability is predicted, causing the machine arrangement to be disconnected from the electricity network.