Steam turbine controller having method and apparatus for providing variable frequency regulation
AssigneeGeneral Electric Company
InventorsBernd Artur Karl Westphal, David Mark Stuebner
Life of this patent
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Abstract
In a preferred embodiment, the invention relates to a steam turbine having a speed-loop droop governor with two load-frequency error gains (droops). The first gain (fast change) may be a conventional high gain that is used for power loads that have a constant frequency. When using only the first gain, the high rate of the first gain causes the droop governor to shut off steam to the turbine if the speed of the turbine drifts above a narrow speed range centered on the rated speed set-point. The second gain (slow change) is a low gain that causes the droop governor to tolerate a wide range of turbine speeds about the rated speed set-point.
Claims15
A method for controlling a steam turbine having a steam valve, the method comprising the steps of:
- a. generating a difference signal indicative of a difference between an actual rotational speed of the turbine and a turbine speed reference;
- b. applying a first gain to the difference signal to generate an uncorrected speed-gain signal;
- c. generating an acceleration signal indicative of a change in the turbine speed;
- d. applying a second gain to the acceleration signal to generate a speed-gain correction signal;
- e. applying the uncorrected speed-gain signal using speed-gain correction signal to generate a corrected speed-gain signal, and
- f. adjusting the steam valve using the corrected speed-gain signal.
A method for controlling a steam turbine having an inlet steam valve, the method comprising the steps of:
- a. generating a difference signal indicative of a difference between an actual rotational speed of the turbine and a turbine speed reference;
- b. applying a slow-change gain (to the difference signal to generate an uncorrected speed-gain signal;
- c. generating a rate of turbine speed change signal indicative of a rate of change of the turbine speed;
- d. applying a fast-change gain to the turbine speed change signal to generate a speed-gain correction signal;
- e. summing the uncorrected speed-gain signal with the speed-gain correction signal to generate a corrected speed*gain signal;
- f. filtering a predetermined narrow range of small range turbine speed variations to generate a filtered corrected speed*gain signal;
- g. combining the filtered corrected speed-gain signal and a load reference to generate a speed and load valve adjustment signal, and
- h. adjusting the inlet steam valve based on the speed and load control adjustment signal.
A controller for a steam turbine having an inlet steam valve comprising:
- a. a speed control logic unit outputting a difference signal indicative of a difference between an input actual rotational speed of the turbine and an input turbine speed reference;
- b. a first gain logic unit applying a first gain to the difference signal and outputting an uncorrected speed-gain signal;
- c. a difference logic unit outputting an turbine acceleration signal;
- d. a second gain logic unit having as inputs a second gain and the acceleration signal, and an output of a speed-gain correction signal;
- e. a summation logic unit having as an input the uncorrected speed-gain signal and an input the speed-gain correction signal, and an output of a corrected speed-gain signal, and
- f. a logic unit having an output of a valve adjustment signal and an input of the corrected speed-gain signal.
Dependencies are inferred from the claim text.