Abstract: A method for monitoring sub-synchronous torsional oscillations of a shaft line of a steam turbine includes measuring a rotational speed of the shaft line over a period of time and generating, from the measured rotational speed, a signal representative of the rotational speed over the period of time. The method further includes performing a spectrum analysis on the signal to determine, for at least one given frequency, an amplitude of variation of the rotational speed at the given frequency, comparing the amplitude with at least one predetermined amplitude threshold for the frequency, and generating an alert signal if the amplitude exceeds at least one predetermined amplitude threshold.

Abstract: A method for monitoring sub-synchronous torsional oscillations of a shaft line of a steam turbine includes measuring a rotational speed of said shaft line over a period of time and generating, from the measured rotational speed, a signal representative of said rotational speed over said period of time. The method further includes performing a spectrum analysis on said signal to determine, for at least one given frequency, an amplitude of variation of said rotational speed at said given frequency, comparing said amplitude with at least one predetermined amplitude threshold for said frequency, and generating an alert signal if said amplitude exceeds at least one predetermined amplitude threshold.