PURPOSE:To promptly adjust a control valve in accordance with the change of pressure in a steam power source and permit a turbine a perform a stable operation of its feed water control, by processing a feedback of stage pressure of the turbine and correcting an opening degree of the turbine control valve. CONSTITUTION:Rotational speeds of turbine 1 can be converted into a true valve of speed by a gear 3, speed detectors 6, 7, speed signal converters 8, 9 and true value selector 10. A speed signal is generated by a feed water controller 11 and signal conversion 12 to be a speed deviation signal in a deviation calculation 13, and a flow rate of steam is obtained by a PI calculation 14. While stage pressures of the turbine are detected by a detector 20, and the difference between the output of the PI calculation 14 and the detected pressure is processed arithmetic operation in a deviation calculation 21, corrected by an amplifier 15 and applied to an adder 22 to output a hydraulic servo position. Further a high pressure control valve 3 and low pressure control valve 4 are open-close actuated by an amplifier 16, electric-hydraulic converter 17, hydraulic servo 18 and link mechanism 19. In this way, a stable running operation can be performed for the turbine without being affected by a change of pressure.
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