多模型切换DMC-PID串级预测控制在SCR脱硝系统中应用的仿真分析  

Simulation Analysis of Multi-model Switching DMC-PID Cascade Predictive Control in SCR Denitration System

作　　者：方垒[1] FANG Lei(Hangzhou Hollysys Automation Co.,Ltd.,Hangzhou,China,Post Code:310018)

机构地区：[1]杭州和利时自动化有限公司,浙江杭州310018

出　　处：《热能动力工程》2023年第4期75-81,共7页Journal of Engineering for Thermal Energy and Power

摘　　要：针对火电厂SCR脱销系统的强非线性、大惯性和大迟延的问题,提出一种新型多模型切换DMC-PID串级预测控制方案。利用改进最小二乘法辨识得到不同运行工况下的局部线性系统模型;根据约束条件,基于二次规划有效集法,求解不同运行工况下的控制器参数;通过负荷指令确定当前的工作条件,设计不同工况下各DMC控制器间的跟踪和无扰切换,基于负荷指令切换开关,提出SCR脱硝系统变工况条件下的多模型切换DMC-PID串级预测控制,实现SCR脱硝非线性系统的全局优化控制。仿真结果表明:与传统的串级PID相比,变工况试验中DMC-PID串级预测控制出口NOx排放浓度超调量减小55.14%、响应速度提高44.23%;外部干扰试验中DMC-PID串级预测控制的氨气阀门开度波动幅度减小85.71%、出口NOx浓度的恢复时间减少26.67%。Aiming at the problems of strong nonlinearity, large inertia and large delay of SCR system in thermal power plant, a new multi-model switching DMC-PID cascade predictive control scheme is proposed. The improved least square method is used to identify the local linear system model under different operating conditions. According to the constraint conditions, the controller parameters under different operating conditions are solved based on the quadratic programming effective set method. The current working conditions are determined by the load command, the tracking and bumpless switching between DMC controllers under different working conditions are designed, and switching is performed based on the load command, a multi-model switching DMC-PID cascade predictive control under variable working conditions of SCR denitrification system is proposed to realize the global optimization control of SCR denitrification nonlinear system. The simulation results show that compared with the traditional cascade PID, the overshoot of outlet NO_x emission concentration under the DMC-PID cascade predictive control is reduced by 55.14% and the response speed is increased by 44.23%;in the external disturbance test, the fluctuation range of ammonia valve opening under the DMC-PID cascade predictive control is reduced by 85.71%, and the recovery time of outlet NO_x concentration is reduced by 26.67%.

关 键 词：DMC-PID SCR系统 多模型切换 无扰切换 串级预测控制 

分 类 号：X773[环境科学与工程—环境工程]