Patent ID: 6865935

Claim:
A control system ( 10 ) for controlling operation of a steam turbine (T) to provide aeromechanical protection of blades (B) of the turbine without overly restricting operation of the turbine, comprising: sensor means ( 12 ) sensing dynamic pressure level variations in a stage (S 1 -Sn) of the turbine; means ( 13 , 14 ) converting a signal (Ps) from the sensor means to a frequency based signal (Fs); and, means ( 16 ) for comparing the pressure levels at various frequencies as represented by the frequency based signal (Fs) to a matrix of limiting values including both alarm and trip signal limits, the control system providing an alarm to an operator of the steam turbine if the comparison indicates that an alarm limit has been exceeded, or taking the steam turbine off line, if the trip signal limit has been exceeded, so to prevent damage to the steam turbine, the control system however maintaining the steam turbine in operation if no aeromechanical disturbances or instabilities, as sensed by the sensor means has occurred.