Abstract: A control system for a steam turbine employs complementary-sized nozzle groups receiving steam in a sequence which employs the smallest possible sized group receiving steam from a control valve of the smallest possible capacity as the governing valve. All other control valves remain either fully open or fully closed. An optimum path may be followed to select a highest-efficiency transition between valve combinations.

Abstract: A steam turbine-generator system includes a reheater bypass valve which cooperates with both a high- and low-pressure bypass valve in the early stages of turbine loading to divert steam in a bypass flow from a high-pressure turbine to the input of a reheat turbine without passing the steam through a reheat portion of the boiler. The pressure and temperature drops in the high-pressure turbine are controlled by the setting of the pressure threshold of the low-pressure bypass valve. A check valve prevents steam flow into the reheat portion of the boiler until a desired operating condition is attained. The steam flowing to the reheat turbine directly from the high-pressure turbine is at a sufficiently low temperature to avoid temperature insult to the rotor of the reheat turbine. Once the turbine is partially loaded, the reheater bypass, high-pressure bypass and low-pressure bypass valves are closed to establish a conventional reheat turbine configuration.

Abstract: A test apparatus and method tests for closure of ganged, cam operated main control valves in a steam turbine. Cam actuation of a set of upper main control valves is separated from cam actuation of a lower set of main control valves. A test controller actuates one of the sets of main control valves in the opening or closing direction and holds the other set stationary while monitoring turbine power output. When the power output has changed by a predetermined amount, the test controller halts actuation of the first-actuated set of main control valves and begins actuating the other set of main control valves in the opposite direction until the turbine power output has changed a predetermined amount in the opposite direction. The process of incrementally closing one set while incrementally opening the other set of main control valves is continued until the set of main control valves being moved in the closing direction should be fully closed.

Abstract: A control system for a prime mover may include a proportional speed control, a primary overspeed control and an emergency overspeed control. The proportional speed signal is obtained from select highest value logic, whereas overspeed and loss of speed signals are submitted to two out of three logic and two out of four logic, respectively. A passive emergency overspeed channel is provided in combination with the primary overspeed channel to respective de-energize and energize trip relays connected to electrohydraulic trip devices.

Abstract: A method of and apparatus for controlling a steam turbine system for a combined cycle power plant using measured parameters to control the position of dampers regulating heat flow to steam generating equipment so as to limit thermal stresses, drum level surge and to provide load-following capabilities.

Abstract: In a power plant which includes a steam turbine with main control valves for admitting steam into the steam turbine and a steam bypass with bypass control valves for diverting steam around the steam turbine directly into a condenser, it is necessary to coordinate the operation of the respective valves so that the steam turbine can be started, brought up to speed, synchronized with a generator and then loaded as smoothly and efficiently as possible. The present invention provides for such operation and, in addition, allows for the transfer of power plant operation from the so-called turbine following mode to the boiler following mode through the use of the sliding pressure concept. The invention described is particularly applicable to combined cycle power plants.