1000 MW二次再热火电机组主蒸汽温度控制策略及工程应用

以具有时变特性、大惯性和非线性的二次再热机组蒸汽温度受控对象为背景,结合超超临界直流锅炉特性,分析了过热器出口主蒸汽温度的变化机理,提出了基于改进型Smith预估补偿器实现的喷水减温控制系统。结合某1 000 MW超超临界二次再热塔式锅炉,给出了控制策略的设计要点。实践证明,该系统能有效解决超超临界二次再热机组主蒸汽温度控制的大延迟和大惯性问题,提高主蒸汽温度的动态控制品质,同时降低调试难度。

The Control Strategy of Main Steam Temperature for a 1 000-MW Double-Reheat Thermal Generation Unit and Its Application

Aim ing at the main steam temperature control of double-reheat units with time variation, large inertia and non-linearity, taking the characteristics of ultra-supercritical once-through boilers in consideration, the mechanism of the main steam temperature changing at the superheater outlet is studied. Then, a water spraying desuperheating control system is proposed based on the improved Smith predictor. The control strategies of the control system are designed for a 1 000-MW ultra-supercritical double-reheat tower-type boiler. The practical operation shows that the control system have effectively tackled the large delay and large inertia problems in the main steam temperature control of ultra-supercritical double-reheat units, improved the dynamic control qualities of the main steam temperature and at the same time alleviated the tuning difficulties.