For the supercritical 600 MW unit in Huadian Suzhou Power Plant

the reheat steam temperature was mainly controlled by the gas damper behind the reheater.At the same time

a minor spray desuperheater was installed on the pipe at outlet of the low temperature reheater as a emergency method to prevent the reheat steam being overheated.Because the reheat steam temperature controlled object had large delay and inertia characteristics and coupled with the boiler burn rate

the original reheat steam temperature control strategy can not adapt to such disturbance conditions as the unit load changing and soot blowing

leading to vibration and overregulation of the reheat gas regulating damper

which resulted in fluctuation of the unit main parameters.Therefore

on the basis of self-adaptive Smith prediction algorithm compensation technology

optimization on the original control strategy was conducted.The reheat steam temperature deviation during the unit load varying was controlled within ±10 ℃

and that during the unit stable operation was controlled within ±5 ℃.The reheat steam temperature control quality and anti-disturbance capacity was improved significantly.