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Turbine acceleration governing system

  • US 4,204,258 A
  • Filed: 10/03/1978
  • Issued: 05/20/1980
  • Est. Priority Date: 10/03/1978
  • Status: Expired due to Term
First Claim
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1. In a turbine speed control system which is operative to control the speed of a steam turbine through a turbine start-up operation by regulating the position of at least one steam admission valve of said turbine in accordance with a speed control function based on a computed speed error between an adjustable speed reference signal and a signal representative of the actual speed of said turbine, said speed reference signal being adjusted, at times, to converge to a desired speed demand signal at a selected acceleration, an improvement comprising:

  • a first controller operative to control the speed of said turbine at selected accelerations from turning gear to a predetermined turbine speed value;

    a second controller selectively operative to govern said turbine accelerations as controlled by said first controller in accordance with calculated present and anticipated rotor stresses of said steam turbine, said second controller performing said rotor stress calculations concurrently with the speed control operations of said first controller;

    means for generating a plurality of signals representative of actual temperature differences of predetermined portions of said steam turbine and for providing said differential temperature representative signals to said first controller;

    and wherein said first controller is further operative to reduce said turbine acceleration to substantially zero upon the detection of at least one of said representative temperature difference signals exceeding a preset limit value respectively associated therewith, said first controller being still further operative to detect when said turbine speed is controllably held substantially fixed in one of a number of predetermined critical speed zones as a result of said acceleration governing by said second controller or as a result of a temperature difference signal exceeding its preset limit value and to adjust said turbine speed outside of said one critical speed zone during either one of said detected turbine speed states.

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