In the field of power system stability there is provided a method of predicting the presence of an out-of-step condition in a power system that includes a plurality of generators, the method including the steps of: (a) obtaining a differential value ({tilde over (δ)}.sub.COI.sup.k) between a rotor angle (δ.sub.k) of an individual one of the plurality of generators and an equivalent rotor angle (δ.sub.COI.sup.k) of the centre of inertia of the remainder of the plurality of generators; (b) processing the differential value ({tilde over (δ)}.sub.COI.sup.k) to determine whether the differential value ({tilde over (δ)}.sub.COI.sup.k) is predicted to reach a predefined reference threshold (δ.sub.threshold); and (c) predicting the presence of the out-of-step condition in the power system if the differential value ({tilde over (δ)}.sub.COI.sup.k) is predicted to reach the predefined reference threshold (δ.sub.threshold).

In the field of power system stability there is provided a method of predicting the presence of an out-of-step condition in a power system that includes a plurality of generators, the method including the steps of: (a) obtaining a differential value ({tilde over (δ)}.sub.COI.sup.k) between a rotor angle (δ.sub.k) of an individual one of the plurality of generators and an equivalent rotor angle (δ.sub.COI.sup.k) of the centre of inertia of the remainder of the plurality of generators; (b) processing the differential value ({tilde over (δ)}.sub.COI.sup.k) to determine whether the differential value ({tilde over (δ)}.sub.COI.sup.k) is predicted to reach a predefined reference threshold (δ.sub.threshold); and (c) predicting the presence of the out-of-step condition in the power system if the differential value ({tilde over (δ)}.sub.COI.sup.k) is predicted to reach the predefined reference threshold (δ.sub.threshold).

A control system for an induction motor executes an on-board, dynamic model to estimate rotor resistance and control the torque output by the induction motor. The model includes equations to calculate stator and rotor temperatures and/or resistances based on combinations of voltage and current data, electrical frequency, rotor speed, switching patterns, and air flow rates during operation of the induction motor. The control system updates the model based on feedback collected during the operation of the induction motor, including the difference between the actual observed stator temperature and the stator temperature predicted by the model. The model is updated to converge the predicted stator temperature on the actual observed stator temperature, and corresponding updates are made to the rotor resistance estimations to provide more accurate estimations of the rotor resistance and improve the accuracy of the induction motor torque output.

In the field of power system stability there is provided a method of predicting the presence of an out-of-step condition in a power system that includes a plurality of generators, the method including the steps of:

(a) obtaining a differential value (.sub.COI.sup.k) between a rotor angle (.sub.k) of an individual one of the plurality of generators and an equivalent rotor angle (.sub.COI.sup.k) of the centre of inertia of the remainder of the plurality of generators;

(b) processing the differential value (.sub.COI.sup.k) to determine whether the differential value (.sub.COI.sup.k) is predicted to reach a predefined reference threshold (.sub.threshold); and

(c) predicting the presence of the out-of-step condition in the power system if the differential value (.sub.COI.sup.k) is predicted to reach the predefined reference threshold (.sub.threshold).

In the field of power system stability there is provided a method of predicting the presence of an out-of-step condition in a power system that includes a plurality of generators, the method including the steps of:

(a) obtaining a differential value (.sub.COI.sup.k) between a rotor angle (.sub.k) of an individual one of the plurality of generators and an equivalent rotor angle (.sub.COI.sup.k) of the centre of inertia of the remainder of the plurality of generators;

(b) processing the differential value (.sub.COI.sup.k) to determine whether the differential value (.sub.COI.sup.k) is predicted to reach a predefined reference threshold (.sub.threshold); and

(c) predicting the presence of the out-of-step condition in the power system if the differential value (.sub.COI.sup.k) is predicted to reach the predefined reference threshold (.sub.threshold).

An alternating current (AC) motor system includes an AC motor with a rotor and a stator with multi-phase AC stator windings. The system also includes a power inverter that generates a multi-phase AC voltage, an AC bus that connects the power inverter to the stator windings, an AC choke that surrounds the AC bus, and a current sensor with a coil wound on or surrounded by the AC choke. The current sensor measures common mode current in the AC bus, and is used in pulse width modulation or slew rate control of the power inverter, ensuring smooth operation and reducing the risk of damage due to common mode current.