基于能量平衡原理的锅炉再热汽温反向建模

Reversed modeling of boiler reheat steam temperature based on energy balance

一个好的汽温模型对机组再热汽温的调节有着重要意义。再热汽温反映了再热器出口蒸汽能量的变化,由能量平衡原理所决定,采用偏最小二乘反向建模的方法对再热蒸汽吸热量进行建模,并结合入口蒸汽能量便可得到再热汽温变化的模型。与传统的直接对汽温建模方法相比,该方法避免了对再热汽温的直接非线性黑箱建模,使模型具有清晰的结构,并提出了具有明确物理意义的单位流量蒸汽吸热能力的概念,便于运行人员掌握和分析汽温变化的本质。结合机组实际运行数据建模,结果表明:非线性偏最小二乘回归的方法能够克服热力系统变量间的多重相关性,所建立的模型具有较高的精度,能够根据模型分析再热汽温异常的原因,量化已有的运行经验,使运行人员快速掌握系统特性,同时也为先进控制策略的应用提供了数据基础。

A good steam temperature model is of great significance for the unit reheat steam temperature regulation. The change of reheat steam temperature follows the basic energy balance principle, this paper establishes an inversed model of the reheat steam heat absorption using partial least squares method; and considering the entrance steam energy, the model of reheat steam temperature can be obtained. Compared with the traditional method of directly estab- lishing steam temperature model, this method avoids the direct nonlinear black-box modeling of reheat steam temperature, also has a clear structure, and puts forward the concept of steam heat-absorbing capacity for unit flow,which has a clear physical meaning. Modeling with the actual operation data, the operation results show that nonlinear partial least squares regression can overcome the multiple correlation among the thermodynamic system variables; the established model has high accuracy, can help the operating staff analyze the cause of anomaly, quickly master the system characteristics, and also provide the data for the application of advanced control strategies.