Westinghouse Electric Corporation

William E Zitelli

Andras I Szabo

James M Mussler

Leaman B Podolsky

Thomas H Schwalenstocker

Alan T Heltsley

A turbine speed control system comprising a pair of concurrently operable electronic microprocessor-based controllers which are coupled together by a data link to functionally cooperate in controlling turbine acceleration primarily during start-up operations in accordance with a set of predetermined measured and calculated turbine conditions. One controller is operative to control the speed of the turbine at selected accelerations from turning gear to a predetermined speed value. This same controller monitors a plurality of temperature differences from preselected regions of the turbine and inhibits turbine acceleration in accordance with an out-of-limit temperature condition associated therewith. In addition, the one controller is further operative to selectively override the turbine speed hold initiated by an out-of-limit temperature condition, the override permitting the one controller to proceed with controlling the speed of the turbine at a desired acceleration. The other controller is selectively operative to govern the turbine acceleration as controlled by the one controller based on calculated present and anticipated rotor stresses which are derived concurrently with the speed control operations of the one controller. A turbine speed hold may be initiated by either a detected differential temperature out-of-limit condition or a detected calculated rotor stress limit condition. In either case, the one controller is further operative to detect if the speed hold occurs in one of a number of predetermined critical speed zones and to adjust the turbine speed outside of the zone in which the speed hold occurs.

Turbine acceleration governing system

A microprocessor-based control system for controlling the speed of a steam turbine by governing the steam supplied thereto from a steam supply source using one or more hydraulically operated servomotor throttle valves is disclosed. The operation of the speed controller is characterized by a plurality of permanently pre-programmed read-only memories containing sets of instructions and data words arranged in an addressable order. The instructions and data words are synchronously processed by the microprocessor as governed by a system clock. Apparatus is provided to initialize the status of the speed controller under the control of the microprocessor in accordance with the processing of one portion of the sets of programmed instructions and data words thereby. The remaining portion of the program is processed by the microprocessor as governed by a real time clock for coordinating the operation of an operator's panel interfaced to the controller and for monitoring the turbine speed and controlling the position of the one or more valve servomotors in accordance therewith. The subportion of the remaining portion of the program primarily characterizing the panel coordination functions is processed during each even period of the real time clock. Accordingly, the subportion of the remaining portion of the program primarily characterizing the turbine speed control is processed during the odd periods of the real time clock.

Microprocessor-based, programmed turbine speed control system

A low-cost, single-point analog subsystem comprising a pre-amplifier signal conditioner, a dual-slope integration analog-to-digital converter, and a computer interface circuit. The unit is capable of rejecting high common mode voltages while maintaining extremely high system accuracies. The main application for the invention is in interfacing transducer or instrumentation analog data with a digital computer. The interface circuitry allows the computer to select its channel in an asynchronous manner through special controllogic and without the necessity for employing conventional multiplexing equipment.

Single-point analog subsystem interfaced with a computer

A microprocessor-based turbine speed controller which incorporates a set of permanently programmable memory devices for characterizing the control of turbine speed in real time is disclosed. A speed monitoring interface circuit included in the speed controller is governed by the microprocessor in accordance with the processing of one program stored in one or more of the permanently programmable memory devices to generate speed measurement data words representative of actual turbine speed. In addition, a power-on initialization circuit initializes the microprocessor at the time of power turn-on to process another program stored in one or more of the permanently programmable memory devices for initializing a plurality of predetermined registers contained in the speed controller corresponding to the characterized speed control operation to be performed by each. Further apparatus and programmed instructions for the control thereof are employed to detect a malfunction in program execution by the microprocessor. Additional apparatus is included to provide a speed control signal output and to condition a plurality of digital input and output signals. All microprocessor processing operations are synchronously time sequenced using the signals generated by a system clock.

Programmable turbine speed controller

A steam turbine control system comprising a primary and an auxiliary manual turbine controller, each said turbine controller including a set of valve position setpoint controllers for close-loop control of the turbine steam admission valves, is disclosed. Each valve position setpoint controller operates, at times, on a position error signal to generate a valve position control signal which controls the rate of valve position movement of a corresponding turbine steam admission valve. The steam admission valves are closed-loop controlled by a selected set of said primary and auxiliary valve position setpoint controllers. The set of valve position control signals corresponding to the selected set of position setpoint controllers are coupled to their respective turbine steam admission valves for controlling the rate of position movement therein. The valve position error and position control signals of the unselected set of said controllers are maintained at approximately zero potential. Transfer logic is provided to coordinate the selection of the primary and auxiliary controllers.

Auxiliary manual turbine controller

A position control system that interfaces turbine control systems with an electro-hydraulic actuator for inlet valves, is disclosed. The system includes a feedback signal generating means that eliminates the effect of differences in ground potentials which would otherwise cause undesirable valve movement and also a proportional plus integral controller that has independent porportionality and reset parameter adjustment. The system also includes a position characterizer that generates independent line segments in the feedback loop, and which provides for selecting monotonically decreasing slopes, or slopes with inflection discontinuities.

Servo control system for electro-hydraulic inlet valves

In an analog data acquisition system, used for digital treatment, analog signals of different levels received from remote locations are amplified with a selected gain before being converted by a common A/D converter. A discretely variable gain amplifier is used in which a series of programmed predetermined ranges are sequentially tested against the capability of the A/D converter in relation to the particular input analog signal. The first acceptable gain is selected and a code can be used to identify the selected gain for digital treatment of the derived corresponding digital signal.

Automatic gain controlled amplifier apparatus

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 system for transferring operation of a mechanism from one control signal to another control signal utilizing frequency modulation is disclosed. A rate multiplier generates pulses at an increasing frequency during a first portion of the transfer period up to a predetermined maximum frequency; and controlled to generate pulses at a decreasing frequency during the final portion of the transfer period. During the first portion of the transfer period, the peak and base of each pulse, corresponds to the value of the one and the other signal, respectively. During the final portion of the transfer period, the peak and base of the pulses are reversed to correspond to the opposite control signals. A filter averages the peaks and bases of the applied pulses during both portions of the transfer period to change gradually the average signal from the one control signal to the other.

Frequency modulation transfer system and method

Low level analog signals from remote locations are amplified after being converted into two consecutive analog signals of opposite polarities and a digital system causes A/D conversion to occur in two successive readings corresponding to said polarities and an algebraic combination of the two successive readings in binary form provides a true reading which is made available for digital processing by a special control circuit.

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Media, PA, United States of America

William E Zitelli