To provide a control system for a fuel gas pressure regulating valve at the time of changing-over of the fuel for a gas turbine, in which hunting in the pressure regulating valve in the low fuel rate-of-flow range is precluded.
A signal from a gas fuel identification signal 21 is inverted by a NOT circuit 15, is fed to a PI controller 11, and operates it in the normal operating mode, and in conformity to a fuel control signal 22, a pressure setting value is emitted by a function generator 13, and a subtractor 12 determines the difference from a gas valve differential pressure signal 23, and the PI controller 11 makes computation and emits a control signal 30 for a fuel gas pressure regulating valve. In the low flow rate range during the fuel changing-over, a low flow rate signal 24 during the fuel changing-over is inverted by the NOT circuit 2 and actuates the PI controller 1 from a control signal line 6, and the PI controller 11 is turned out of operation by another control signal line 5, and the difference signal from the input line 4 is fed, and upon computation, a control signal 30 is emitted. Thus hunting in the pressure regulating valve 40 in the low flow rate range is precluded.
TAKASU MOTOSHI
MURAKAMI TAKUMI
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