De-synchronisation determination for a synchronous machine - uses functional value of base and harmonic components airgap flux and allows network disconnection

摘要

The desynchronisation determin. system for a synchronous electrical machine uses the functional value of the magnetic air-gap flux. The latter incorporates a functional value for the base oscillation component and a functional value for the higher harmonic components. Desynchronisation is indicated when the ratio of the base component value to each of the harmonic component values drops below a given reference value. The desynchronisation is indicated by detecting a drop in the absolute value of the longitudinal flux as well as the transverse flux. The system is applicable to a synchronous motor, a phase-shifter or a synchronous generator and allows a machine going into desynchronisation to be detected before it can effect the whole network.