FCB过程汽轮机转速控制策略的仿真分析与研究

Simulation Analysis and Research on Rotor Speed Control Strategy of the Steam Turbine in FCB Process

快速甩负荷(FCB)是大型火电机组极为严峻的工况,在此过程中汽轮机的转子转速是至关重要的控制参数。为此,建立汽轮机本体典型环节的传递函数模型,采用Simulink软件搭建汽轮机的调节系统并添加相应的超速保护逻辑,对FCB过程中转速的动态特性进行仿真分析。根据已有的控制经验,分析一、二次调频功能、各项超速保护动作以及机组设计参数对转速控制的影响,仿真过程能够较为准确地反映不同条件下转速的响应趋势。结果表明:FCB过程中增大一次调频功能,加入二次调频功能是减少转速最大动态偏差、消除静态偏差的有效措施,在此危机时刻具有预警性的超速保护动作是必不可少的,减少阀门动作迟延且合理设定阀门关闭时间是转速控制的关键。

FCB is an extremely serious condition for large scale thermal power units, during this process, the rotor speed of steam turbine is the most critical control parameter. Therefore established typical transfer function model of the steam turbine ontology, then set up turbine control system and construct over speed protection logic via the Simulink simulation platform to simulate the speed dynamic characteristics in FCB process. According to the existing control experience,the simulation can reflect the corresponding trend of the rotating speed under different conditions includes the first and the secondary frequency modulation function, over speed protection actions as well and the unit design parameters. Results show that in the process of FCB, enhanced the first frequency modulation and introduced the secondary frequency modulation can reduce the maximum dynamic deviation and eliminate static deviation effectively, the over speed action with early warning is essential in times of crisis, reduced the delay of valve action and set up valve closing time is the key to control the rotating speed.