Aiming at soling such problems as large overshoot and unstable which existed in backpressure control system of air-cooled island for 600 MW direct air-cooled unit of Hequ Power Plant in Shanxi province

improvement measures including adding anti-interference circuit and adaptive adjustment parameters have been proposed to optimize the control logic of anti-freeze protection and cut step operation of air cooling fan.After the optimization

the maximum deviation of the backpressure was below 0.8kPa in start up process of the unit.It has been proved that the proposed measures have ensured the stability of the backpressure control and realized the whole process automation of air-cooling system

which to some extend have enhanced the economy

stability and safety during the operation of above-mentioned air-cooling unit.