A method and apparatus for controlling the operation of a steam turbine system, which system includes a source of steam under a controllable pressure, a plurality of governor valves connected between the source and the turbine first stage, each governor valve being movable between two selected positions each creating minimum steam flow throttling losses, a system control device (2) for producing a system control signal representative of the desired power level to be supplied by the turbine system, and a governor valve control (8) connected for producing a valve control signal in response to an input signal and for positioning each governor valve in accordance with the value of the valve control signal. During operation, the input signal to the governor valve control (8) is given a value which is based on the system control signal and which causes the valve control signal to have a value which will place each governor valve at least approximately at a selected position. In order to position the governor valves more accurately, the rate of flow of steam from the steam source is measured (18); the difference between the measured rate of flow and the expected rate of flow of steam from the steam source is determined (20, 24); and the value of the input signal to the governor valve control is modified (6, 12) in response to the difference determined in a direction to vary the positions of the governor valves in a manner to reduce the magnitude of that difference.

For setting the position of a control element, a controller and method according to the invention provide for impressing a required temporal characteristic of the actuating signal onto a should-be value then using said should-be value as a time-variable signal for forming the actuating signal.

In a steam turbine power plant, a deaerator is heated and pressurized by extraction steam from the steam turbine for the purpose of preheating feedwater to the power plant boiler. Under certain conditions, the available steam to the deaerator is insufficient to adequately maintain pressure in the deaerator leading to steam voids with a rapid rise in deaerator water level which could cause damage to the deaerator, feedwater pumps or the turbine and lead to a power plant shutdown. A second source of steam is available to provide steam under these conditions and a control system for controlling the steam input into the deaerator is shown. Under conditions of falling pressure, if a certain rate is exceeded, the second source of steam is input into the deaerator to maintain adequate pressure for stable operation.

A method and apparatus for protecting a turbine from undesirable temperature and pressure variations wherein an acceptable range of actual pressure and temperature variations is established, a first alarm signal is generated only if the acceptable range is exceeded by actual temperature or pressure, a second signal is established representing an acceptable rate of change of said actual pressure or temperature and a second alarm is generated if the actual rate of change of pressure or temperature exceeds the acceptable range of pressure or temperature whereby the second alarm signal is produced only when the first alarm signal is generated. In addition, a third signal is established representing a maximum rate of change of pressure and a third alarm signal is generated if the actual rate of change of pressure or temperature exceeds the maximum rate of change of pressure or temperature whereby the third alarm signal is produced only when the first alarm signal is generated.

A method and apparatus for controlling a valve/actuator plant by generating a plurality of independent correcting control signals each responsive to a plurality of respective input signals and at least one of these input signals being the set point signal. The plurality of independent correcting control signals includes a pneumatic flow signal. The correcting control signals may be derived from all linear control signals, all non-linear control signals, or a combination of linear control signals and non-linear control signals.