Adaptive Robust Control for the Steam Temperature of Thermal Power Plant in Sliding Pressure Operation

为研究火电厂滑压运行方式，利用模块化建模系统(MMS)开发了一套模拟器。MMS提供了大量的模块，这些模块是根据热力学定律开发的。这些模块包括锅炉、过热器、减温器、汽轮机、省煤器、风管、冷凝器、除氧器、给水加热器等。使用200个彩信模块以及从工厂和制造商采集的数据开发了模拟器，并进行了多项研究，以验证所开发的模拟器的准确性。结果表明，该模拟器在额定负荷下的结果与实际装置的结果吻合较好。虽然通过仿真实例证明该模拟器是稳定的，但在计算方面仍存在一些问题。这个模拟器在计算上是“僵硬的”，因为有非常快的模式和非常慢的模式。快速模式源自涡轮机和SLO…锅炉和再热器有较多的w个工况。当负载需求变化较大时，仿真会耗费大量的CPU时间。由于计算刚度较大，难以对模拟器的动态精度进行验证。在研究了现有的基于PI的控制系统的基础上，提出了一种新的控制系统结构，该结构由主蒸汽负荷和压力对燃油流量控制系统和主蒸汽温度控制系统的前馈控制动作组成。所提出的FF控制可以嵌入到目前基于PI的控制系统中。为了设计现场总线控制器，建立了锅炉对象的时变模型。该模型是由锅炉厂在不同负荷和压力要求下的几个线性化模型进行内插的。这些线性化的模型通过用伪随机二进制序列(PRBS)激励仿真器来辨识。根据该时变模型，设计了一种按负荷和压力要求进行增益调度的FF控制器。针对负荷压力需求阶跃变化较小、负荷压力需求阶跃变化较大的情况，进行了大量的仿真研究。仿真结果令人满意。主汽温的控制误差比不带FF控制器的控制误差降低了50%。较少

A simulator has been developed for the purpose of studying of the sliding pressure operation method for thermal power plants by means of MMS (Modular Modeling System). There are a lot of modules supplied by MMS,which are developed based on the laws of thermodynamics. These modules are boiler, superheater, attemperator, turbine, economizer, piper, condenser, deaerator, feedwater heater, and so on. Two hundreds of MMS modules are used to develop the simulator together with the data collected from real plant and manufactory.Several studies have been done in order to validate the accuracy of the developed simulator. It is shown that the results of the simulator at the rated load are agreed with that of the real plant well. Although the simulator is ahown to be stable by simulation examples, there still exist some problems in calculation aspects. The simulator is 'stiff' in calculation, because there are very fast modes and very slow modes. The fast modes originate from the turbine, and slo … More w modes originate from the boiler and reheater. The simulation costs amount of CPU time if demand of load is changed largely. The calculating stiffness makes it difficult for us to validate the dynamic accuracy of the simulator. A simlified simulator has then been developed in order to improve the calculating efficiency.After studying the current PI based control systems of the real plant, we have developed a new control system structure which is composed of a FF (feedforward) control action from the demands of load and pressure of main steam to fuel flow rate control system and temperature control of main steam. The proposed FF control can be plugged in the current PI based control systems. In order to design the FF controller, a time varying model for boiler plant is developed. This model is interpolated by several linearized models of the boiler plant at several levels of demand of load and pressure. These linearized models are identified by stimulating the simulator with PRBS (pseudo random binary sequence). According to this time varying model, a FF controller that is gain scheduled by demands of load and pressure is developed. A lot of simulation studies have been carried out for cases of small step change of demand of load and pressure and large ramp change of demand of load and pressure. The simulation results are satisfactory. The controlled error of main steam temperature has been reduced to 50% comparing with that of without FF controller. Less