1000MW超超临界机组给水控制系统分析及其优化

Analysis and Optimization of Feed Water Control System in 1 000 MW Ultra-Supercritical Units

以某电厂为例,介绍和分析其1 000 MW超超临界机组给水控制功能及特点。在湿态方式下,给水控制要满足水冷壁最小流量的要求且维持一定的分离器水位。在干态方式下,其任务主要是调节合适的煤水比,控制好分离器出口焓值(温度),实现对主蒸汽温度的粗调。由锅炉主控确定的给水前馈加上控制焓值的反馈调节形成最终的给水指令,分别根据分离器温度是否超T MAX1值和过热减温喷水量实际值和设定值之间的偏差对焓值设定值进行修正。最后介绍了对给水控制进行的一些优化,以提高机组运行可靠性和变负荷性能。

Feed water control function and characteristics of 1 000 MW ultra-supercritical units in a power plant are il- lustrated and analyzed in this paper. In wet mode, feed water control should meet the requirement of minimum flow for water wall and maintain the certain water level in cyclone; in dry mode, its main function is to adjust fuel-water ratio, to control enthalpy （temperature） at cyclone outlet, and to primarily regulate the main steam temperature. Fi- nal feed water command is regulated by the feed forward command determined by boiler master, plus feedback com- mand of enthalpy control. The enthalpy set point is modified respectively by the temperature deviation between cy- clone outlet and T MAX1, and by the flow deviation between actual value and design value of de-superheat spray wa- ter. Some optimizations for feed water control are applied to improve the unit operation reliability and load changing capability.