The control system in air-cooled island

i.e.the air-cooled condenser

for 2×600 MW direct air-cooled units in fourth-phase project of Dalate Power Plant has been presented.Directing againt the existing problems

such as the control logic of antifreezing protection can't skip over the programmed sequence

and the larger deviation of control regulation for steam turbine backpressure making the automatic control unable to put into service.etc.

an optimized scheme

in which the set value of steam turbine backpressure during the time of establishing vacuum being modified

the step sequence of excecutive programme being adjusted

and the pure integral regulation in automatic control of steam turbine backpressure having been revised into proportional integral regulation

avoiding the influence of external disturbance upon the said backpressure

has been put forward.After optimization

automatic control in the whole process of air-cooled island for the units has been realized.