基于抗扰动Smith预估补偿的磨煤机出口风粉温度优化控制
Optimization control of pulverized coal mill outlet air temperaturebased on anti disturbance Smith predictive compensation
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摘要: “双碳”背景下,作为高能耗高排放的火电机组,其燃烧性能直接影响发电效率和碳排放量。锅炉燃烧优化控制对运行优化和灵活调峰是有重要意义。电站锅炉磨煤机的出口风粉温度控制面临大延迟、多干扰问题,对燃煤机组安全稳定运行具有重要影响。基于Smith预估控制器,在补偿回路中增设反馈环节,实现了高效抗干扰,提升磨煤机风粉温度控制性能。通过Taylor级数展开和待定系数法求取模型近似转换参数,获得一阶惯性纯滞后模型,进而设计抗扰动型Smith预估补偿控制器。通过与单回路PID控制试验对比,发现Smith预估补偿控制算法可有效补偿控制对象的纯延迟滞后环节,单位阶跃响应超调量降低36.5%,调节时间缩短65.8%。相比经典Smith预估补偿控制算法,抗扰动Smith预估补偿控制算法可提高控制算法的抗扰动性能,并显著改善控制对象的动态特性,单位阶跃响应超调量减小44.7%,调节时间缩短15.7%。同时,实现了扰动最大偏差和收敛时间的降低。最后,在某660MW超临界一次再热燃煤机组上应用该方法,实现了磨煤机出口风粉温度实际值对设定值的平稳跟踪,进一步验证了该方法的有效性。Abstract: Towards the goals of carbon peaking and carbon neutrality,as a thermal power unit with high energy consumption and high emission,its combustion performance directly affects the power generation efficiency and carbon emission. Optimal control of boiler combustionis important for operation optimization and flexible peak shifting. The outlet air powder temperature control of the coal mill in a power station boiler is subject to significant delays and multiple disturbances,which have a profound impact on the safety and stable operation ofthermal power units. This paper proposed a feedback link in the compensation loop based on the Smith prognostic controller to enhance theanti-interference capabilities and performance of the air powder temperature control of the coal mill. The first-order inertia pure hysteresis model was obtained by Taylor series expansion and the method of coefficients to be determined to obtain the model approximation conversion parameters. The anti-disturbance Smith prediction compensation controller was then designed. A comparison with the single-loopPID control experiment reveals that the Smith prediction compensation control algorithm can effectively compensate for the pure delay laglink of the control object. The overshoot of the unit step response is reduced by 36.5% and regulation time is reduced by 65.8%. In comparison to the classical Smith prediction compensation control algorithm,the anti-disturbance Smith prediction compensation control algorithm demonstrates enhanced anti-disturbance performance and notable improvements in the dynamic characteristics of the control object.The overshoot of the unit step response is reduced by 44.7%,and the regulation time is shortened by 15.7%. At the same time,a reductionin the maximum deviation of the perturbation and the convergence time is achieved. The method of this paper was applied to a 660 MW supercritical primary reheat thermal power unit to realize the smooth tracking of the actual value of the air powder temperature at the outlet ofthe coal mill to the set value. The effectiveness of this paper′s method was further verified.
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