Abstract: The disclosed system overlaps the control operation for throttle and governor valves to shorten a steam chest warmup period by fully opening a pilot valve and closing down the governor valve to maintain rolling speed when the steam chest needs wraming and the throttle valve - governor valve transfer speed has not been reached. The system also sets a minimum rate of acceleration for vibration run through periods and allows speed changes at designated periodic speed change windows as long as stress is within an allowable range. The system further eliminates vibration transients during a speed change operation by providing a smoothed trend preventing speed holds from increasing unnecessarily.

Abstract: A method for accumulating stress damage induced by temperature differentials in a rotor of a high pressure steam turbine utilizes a representation of stress damage corresponding to a period of continuous temperature change. A counter variable associated with the representation of stress damage is incremented each time there is a significant change in direction of change in stress induced in the rotor. Accumulated stress damage is calculated by summing the products of each counter variable times a coefficient of stress damage corresponding to that counter variable. Accumulated stress damage is added to previously accumulated stress damage, calculated prior to resetting of the counter variables, to produce total accumulated stress damage. The total accumulated stress damage is printed on a permanent storage medium, such as paper, and it is compared with an alarm setpoint. If the alarm setpoint is exceeded, a message is sent to the operator and the operation of the steam turbine may also be adjusted.

Abstract: A method for automatically calibrating a controller for a valve controlled system follows consistent procedures to make precise adjustments to valve characteristics. The controller is placed in a calibration mode, then the valve settings are modified over a full range of operation. At predetermined levels of operation, the valve settings are maintained at preset values while system performance is measured. After the full range of valve operation has been covered, adjustments are made to the correspondence between the valve settings and the levels of operation in dependence upon the differences between the measured system performance and the predetermined levels of operation. This procedure is repeated to provide average values and also to make changes to valve characteristic curves corresponding to different modes of operation such as single valve and sequential valve modes. Other control parameters may be adjusted by evaluating system performance during normal operation.

Abstract: A steam turbine inlet valve control system includes separately tunable valve characteristics for single valve and sequential valve operation modes. The sequential valve characteristics include both normal and alternate sequences which can be selected during operation of the steam turbine. The characteristics may be displayed to an operator and modified by graphical manipulation to simplify tuning the control system's characteristics to the steam turbine's operation. The control system also performs direct tracking of flow through the valves by converting sensed position signals to individual valve flow signals using a lift-to-flow conversion characteristic. Individual valve flow signals are summed and corrected for choked flow conditions to produce a tracked flow demand signal.