TURBINE BYPASS VALVE CONTROL DEVICE

PROBLEM TO BE SOLVED: To keep as a whole balance of the system for avoiding an excess discharge of steam to a down stream of each turbine bypass by controlling openings of high pressure and low pressure turbine bypass valves when a load decrease suddenly by turbine load rejection. SOLUTION: This plant comprises steam generators 1 and 7, turbines 5, 13, a condenser 14, steam pipes 2, 8 guiding steam from the steam generators 1, 7 to the turbines 5, 13 and steam pipes 21, 35 which has turbine bypass valve 22, 36 bypassing turbine so as to guide the steam of the steam generator from the steam pipes 2, 8 to the condenser. In this case, means 29, 30 which set an opening upper limit obtained from steam pressure in the steam pipes 2, 8 to a control signal (output of PI25) of the turbine bypass valves are provided so as to detect a pressure return after increasing steam pressure when a load of the turbine and keep the turbine bypass valve to the opening upper limit when the pressure returns specified pressure.