单元机组过热汽温控制系统的负荷适应性

Study on Load Adaptability of Superheated Steam Temperature Control Systems for Monoblock Units

为了增强过热汽温控制系统的负荷适应能力,以一个600MW机组的过热汽温系统为研究对象,设计了由4组局部控制器组成的负荷调度控制系统,并以主蒸汽流量作为系统的调度变量。每一组局部控制器对应一种典型工况,采用串级内模原理进行设计和整定,其中,高阶的外回路控制器通过Taylor级数展开的方法简化为实际PID形式。控制系统各局部控制器之间的跟踪与无扰切换通过Hanus方法实现。系统保留了传统串级控制系统克服内回路扰动、提高系统工作频率的优点。在不同负荷下的仿真试验以及大范围变工况试验均表明,该系统具有良好的负荷适应能力。

In order to improve the load adaptability of superheated steam temperature control systems, a load tuning and control system, consisting of 4 sets of localized-controllers has been designed, taking the superheated steam temperature control system of a 600 MW unit as the object of study, with fresh steam flow as the tuning variable. Each controller, corresponding to one typical mode of operation, is designed and tuned according to the cascade internal model control theory. The outer-loop controller which is of a higher order is simplified to real PID form by making use of Taylor＇ s series expansion. Tracing and undisturbed switching between controllers is realized by the Hanus method. The system has retained the advantages of traditional cascade control systems, which consist of overcoming inner-loop disturbances and increasing the working frequency of the system. Simulation tests under different loads and wide ranging load variations show that this system has a good load adaptability. Figs 5, tables 3 and refs 3.