Westinghouse Electric Corporation

Leaman B Podolsky

Morton H Binstock

Thomas H McCloskey

Francesco Lardi

Andrew S Braytenbah

Theodore C Giras

Uri G Ronnen

Charles L Groves, Jr

Gary W Berkebile

William E Zitelli

Steven J Johnson

A bypass system for a steam turbine wherein the energy level of the steam bypassed around the intermediate pressure and low pressure turbines is modified by introduction of cooling water. The amount of water introduced is adaptively varied as a function of the enthalpy of the bypassed steam as measured by a sensor in the steam path.

Turbine low pressure bypass spray valve control system and method

A DEH (digital electrohydraulic) control system for a steam turbine generator having a steam bypass system. The turbine system includes a high pressure turbine having throttle and governor steam admission valves as well as an intermediate pressure turbine having stop and interceptor steam admission valves. The turbine is brought on line by initially controlling steam admission into the intermediate pressure turbine by modulating the interceptor valve in response to a speed error signal generated as a result of the difference between actual and a predetermined reference speed. During this initial control the throttle valve remains in a closed position. When the turbine speed has attained a preset value such as half of synchronous speed, the interceptor valve is held at the same position it was in when the preset speed was attained and the throttle valve is controllably open in response to the same speed error signal. After a preset transfer speed has been attained, control of steam admission to the high pressure turbine is transferred to the governor valve and after synchronous speed has been reached the DEH system switches to a load control mode wherein the signal which controls the positioning of the governor valve is also utilized to control the interceptor valve position. The interceptor valve thereafter will reach a wide open position at a predetermined load. During the speed control mode of operation the control signal which controls the positioning of the interceptor valve is modified by certain pressure conditions at the input of the interceptor valve after the preset speed is attained.

Control system and method for a steam turbine having a steam bypass

A bypass system for a steam turbine wherein the temperature of the steam bypassed around the high pressure turbine is accurately controlled by measuring the inlet and outlet temperatures of the boiler reheater and generating an adaptive set point. The set point value is used to govern operation of a spray valve which admits cooling water to the bypass steam path.

Turbine high pressure bypass temperature control system and method

A steam turbine system which includes a steam generator and a steam bypass path for bypassing steam around the turbine. The outlet throttle pressure of the steam generator is controlled by controlling admission of steam into the bypass path by means of a bypass valve. A desired throttle pressure set point is generated which is independent of steam flow and this set point is compared with the actual throttle pressure for governing the bypass valve during turbine start-up. When the turbine is fully operational the bypass valve control is effected by a comparison of the actual throttle pressure with the desired throttle pressure set point plus some bias.

Turbine high pressure bypass pressure control system

A system and method for operating a turbine power plant, wherein a demand signal based upon load or total turbine steam flow required for a predetermined level of operation controls the value of individual signals representative of valve position for respective steam inlet valves in the single and sequential mode of operation, is disclosed. Each individual valve position signal, which is representative of a selected portion of the total demand signal, is dynamically calculated to reflect the effect of the pressure drop across the nozzles, and to correct for the number of inlet nozzles, associated with each valve. The total demand signal is modified in accordance with actual throttle pressure over a period of time that is dependent on the amount of throttle pressure change.

System and method for controlling a turbine power plant in the single

A system and method of operating a turbine power plant utilizing a digital computer to transfer automatically between a single valve mode and sequential valve mode of operation and vice versa without disturbing the load or steam flow demand to the turbine, is disclosed. Selecting the other mode of valve operation when operating automatically in one valve mode results in the generation of physical representations corresponding to the desired flow through each of the valve means in such other mode at the operating load or flow level. The flow in the one mode and the desired flow in the other mode is used to generate a representation based on flow change for each valve means. A number of increments of valve flow change for each valve means is determined in accordance with the largest valve flow change and a predetermined limit. The size of each incremental change is determined in accordance with the respective valve flow change. The position of the appropriate valves are changed simultaneously at periodic time intervals to change the flow at each interval corresponding to its respective incremental flow change until the turbine is operated in the selected mode. A change in total steam flow demand of the turbine during such transfer suspends the transfer and changes the steam flow of the valves equally in accordance with such change. If the position of the valves does not permit an equal allocation of the total change, such change is allocated to the extent of such valves capability and the remaining change is allocated equally among the remaining valves. The transfer is resumed subsequent to effecting the total flow change.

System and method for transferring the operation of a turbine-power

A steam turbine is provided with an automatic digital computer controller and a backup analog controller which are interfaced with an electrohydraulic position control for the turbine throttles and governor valves. Valve position signals are generated by transducers and applied to the valve position control along with position setpoint signals from the computer or the backup controller for the purpose of generating valve control signals which drive the valves until the position setpoints are satisfied. The position signals are also applied to the computer where they are compared to the computer valve position setpoints. The automatic controller and the analog backup controller each have a speed/load control which generates the valve position setpoints in accordance with a speed or load reference, and the backup control tracks the computer setpoints during automatic control. The backup control position setpoint signals are also applied to the computer during automatic control there they are also compared to the computer valve position setpoints. If any comparison results in a difference in excess of a predetermined deadband valve, the computer generates a contingency signal to indicate a valve not functioning or backup not tracking.

System and method for operating a steam turbine with protection

A system for indicating optimum positioning of steam inlet valves to minimize steam throttling losses during operation of a turbine power plant in the sequential valve mode is disclosed.

Optimum sequential valve position indication system for turbine power

In a system and method for automatically starting, synchronizing and operating a steam turbine, proportional plus integral feedbck control utilizing digital computer systems is adapted to correspond to physical valve operation by applying integration limits. Useful for both speed and load control modes of operation, the demand signal is compared with prior values thereof, and the differential is both multiplied by a proportional gain factor, and integrated in the computer utilizing numerical integration techniques. The integrated total is kept within a desired range by applying upper and lower limits, and the limited integral is combined with the proportional factor, further limited, as desired, and appropriately scaled for use as a process variable.

System and method for operating a steam turbine with digital computer

A system for detecting the failure of steam inlet valves to respond properly to their respective control signals, is disclosed. The detection of such a contingency provides an appropriate indication, and also initiates a transfer to single valve operation when operating in the sequential valve mode. The system provides for indicating and/or transferring to single valve operations only after the contingency has been detected for a predetermined interval to compensate for the velocity limiting characteristics of the valve actuators.

Valve contingency detection system for a turbine power plant

A steam turbine control system includes an operator panel and a digital computer which operates the turbine valves through an electrohydraulic control. Turbine speed and load signals and valve position signals are coupled to the computer for use by the computer control loops in developing valve control signals. Two separate displays are provided on the operator panel, one for the speed or load reference and the other for the speed or load demand. Dedicated pushbuttons on the panel enable certain other parameters such as acceleration or load rate or valve position limit to be displayed in the reference display, while other pushbuttons can be used to address and display in the reference or demand display general control system parameters. A mechanism is provided for entering changes into the computer for the various parameters and for displaying such changes in one of the displays.

System and method for operating a steam turbine with improved control

A digital transfer system for transferring the operation of a steam turbine between a single and sequential mode of operation is disclosed. A total flow demand signal is applied to all of the valves in parallel for the single mode; and applied to all of the valves through individual function generators for the sequential mode. A digital up/down counter is connected to a rate multiplier for generating pulses at a frequency corresponding to the status of the counter. An electronic switch is connected to conduct either the single or sequential mode signal to the valve operating mechanism to respond to the pulses for repetitively applying alternately the single and sequential mode signal during the transfer. Digital components both control and are controlled by the counter to increase incrementally the frequency of operation of the electronic switch to apply the particular signal toward which the transfer is being made at such increasing frequency during the first portion of the transfer period and to incrementally decrease the operating frequency of the switch and apply the particular signal from which the transfer is made during the final portion of the transfer. Provision is made to adjust the period of transfer; and to stop or reverse the transfer between modes at any period during the transfer.

Digital transfer control system for dual mode turbine operation

A combined digital computer/analog control system for operating a boiling water reactor steam turbine power plant, wherein the digital computer provides a throttle pressure setpoint, speed error and load demand for controlling the plant depending upon the operational states of the system, is disclosed. The analog portion of the system also controls the plant in cooperation with the digital computer for certain operational states and conditions when the digital computer is in operation; and the analog system alone controls the plant when the digital computer is out of service. The transfer between such control is effected depending upon the operational states of the system and certain of the components therein. The system also includes in the digital computer portion, the provision for preventing a load demand which is outside the limits of the reactor circulation system when the reactor is in a state of automatic operation.

System for operating a boiling water reactor steam turbine plant with a

A combined digital computer/analog control system for operating a boiling water reactor-steam turbine-power plant wherein one of two analog throttle pressure controllers is used for controlling the inlet and bypass valves. One of the pressure controllers is biased to provide a higher signal than the other; and such nonbiased controller is the one selected to control the valves. Each controller includes a pressure transducer, a summing device and amplifier, and a lead/lag circuit together with the appropriate power supply. A failure detection system is used to switch the controllers from automatic to manual when a predetermined combination of controller components becomes defective. Also, such system is so organized that a transducer failure for one controller causes the other controller to assume control regardless of whether such failure results in a higher or lower than proper signal.

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Wilmington, DE, United States of America

Leaman B Podolsky