On the basis of anlaysising bypass system of steam turbine for M701F gas-steam combined cycle unit and the pressure control mode of bypass valve

the countermeasures in control under special operation conditions

such as the start-up sitation of unit doesn't match with the situation of waste heat boiler

HP-and MP-steam pressure before start-up of unit are higher than the set value of minimum pressure

as well as unsmooth jamming of the bypass valve during start-up of unit

have been put forward

thereby ensuring safe operation of the unit.