柴油机Urea-SCR装置非线性自抗扰控制系统研究

A nonlinear active disturbance rejection control system for the urea-SCR device in a diesel engine

针对柴油机SCR装置现有控制系统精度低和动态响应性能差引起NO_x排放超标的问题,本文依据非线性自抗扰控制理论,采用快速跟踪微分器和非线性组合提高SCR控制系统的动态响应性能,将控制系统所处的内外扰动归结为"总和扰动",并利用扩张状态观测器估计和补偿总和扰动作用。研究结果表明:基于非线性自抗扰控制技术的SCR装置控制系统具有良好的扰动抑制能力和动态响应性能,可以有效地避免柴油机NO_x排放超标,能够支撑现阶段的国五排放型式认证,并对国六阶段SCR装置控制方案开发提供重要的指导作用。

NOx emission from diesel engines exceeds the standard value owing to the low control accuracy and poor dynamic response performance of existing urea-SCR （selective catalytic reduction） device control systems. T o en-sure reliable application of SCR devices on diesel engines,a nonlinear active disturbance rejection controller （NADRC ） was applied to the SCR control system. In this system, a fast tracking differentiator and a nonlinear combination were adopted to improve the dynamic response performance; moreover,an extended state observer was used to estimate and compensate the total disturbances to ensure the accuracy of N O x emission. According to the results,the improved SCR control system showed a good disturbance rejection ability and an excellent dynamic response performance. This robust SCR control system can effectively prevent NOx discharging beyond the emission limits for diesel engines （ China 5）. T he optimized S C R control system could further provide an important guideline for the development of SCR devices for diesel engines （ China 6）.