燃气蒸汽联合循环燃料系统动力学建模的分析研究

Study on dynamical modeling of the fuel system in gas-stream combine cycle systems

为了提高燃气轮机联合循环动力学建模的精度和适用范围,对影响燃料量的因素进行全面分析.提出将燃料量作为复合自变量进行燃料系统建模的必要性,确立以燃料指令、分配系数、机组负荷、转速和燃料低位发热量作为其简单自变量,采用模块化的灰箱建模法建立燃料系统动态模型.对仿真与实际机组的燃料指令和流量之间的匹配关系进行了研究,提出以燃料设计热耗量为枢纽的仿真系统燃料流量修正方法,建立了更加精确的稳态模型,提高了联合循环动力学模型对于燃料种类变化的适应能力.利用所建立的模型对气、液燃料的切换、混烧过程及机组起动过程进行了数字仿真,分析研究了其动态特性,表明该模型的精度和适应性得到明显的提高.

To improve the accuracy and adaptability of the dynamical modeling on combined cycle of gas turbines (CCGT), the factors related to fuel quantity are discussed in all-around way and the demand of modeling on fuel system of CCGT is put forward. In the modeling, the fuel flux is regarded as a complex independent variable, and the fuel instructor, the ratio between the liquid and gas fuel, the load, the speed and the quantity of heat in low level are all regarded as the directly independent variables of the fuel system. The dynamic model of the fuel system is founded in the blocking and grey-box method. The matching relation of fuel instruction and flux quantity between emulational and real units is studied. A method on modifying fuel flux by the quantity of fuel heat at its designed point is brought forward and a more precisely steady model is founded which is more adaptive to the changing of fuel sorts. The model is tested in digital simulation experiment on fuel switching, mixing and unit start-up, and the conclusions above are proved.