PID参数自整定方法在热风炉燃烧控制中的应用

热风炉是高炉生产系统中重要的组成部分,其燃烧控制是一个相当重要的部分。但是国内大部分的中小型热风炉参数的设置几乎都采用常规PID,这样受人为因素影响严重,不能达到节约能源和优化控制的目的。因此,运用合适的PID参数自整定方法来代替常规PID整定,对煤气和空气流量进行控制,进而改善热风炉的送风效果显得尤为重要。本文设计了热风炉的燃烧控制方案,然后具体对几种不同的PID自整定方法进行研究,并以工业控制系统中常用的带有时间延迟的一阶模型为例,运用MATLAB对具体的PID自整定方法进行研究与仿真。同时,对仿真结果进行比较,得到了各种自整定方法的控制效果和适用范围。以便将PID自整定方法运用到热风炉的燃烧控制中,进而改善其燃烧效果。     

基于类前馈解耦的双模糊控制在电站锅炉燃烧系统的仿真研究

为了进一步提高目前电站锅炉燃烧系统的控制性能,在分析了某亚临界锅炉燃烧系统动态特性与影响因素的基础上,将各回路主控制器采用可以适时调整控制器参数的模糊自适应PID控制器,并且根据前馈补偿解耦原理在各耦合回路间增加类前馈补偿的模糊解耦控制器来实现全新的燃烧系统优化设计;通过MATLAB仿真表明,采用文章提出的双模糊控制策略相比常规的模糊自适应PID控制,响应时间缩短了45.2%,超调量降低了53.6%,调节时间减少了32.7%,鲁棒性增强,控制性能有了很大提升。     

基于模糊PID的磁悬浮球控制系统研究

针对磁悬浮球系统的本质不稳定性,设计模糊PID算法实现系统的稳定控制,并使之动态性能及稳态性能满足要求;文中首先分析了磁悬浮球系统的基本原理,并进行力学分析,建立系统的数学模型,并对其中的非线性部分进行了平衡点处的线性化,而后采用用PID控制设计,PID可以实现系统的稳定控制,且控制精度较高,但对于动态性能的改善不足,且当模型中的参数改变时,PID参数的适应性较差;因此在PID参数的基础上,采用模糊PID控制,使得系统既可以满足三性要求,又可以使其具有参数变化的适应能力。     

基于PID控制器的HDRI系统的研究

HDRI系统是指进行高动态范围图像采集的成像系统。在使用空间光调制器进行反馈调制从而获取宽动态范围图像的系统中,由于未知景物光强范围很大,会导致反馈耗时或振荡。提出了一种将控制理论中的PID技术应用于反馈调制系统的调整方法。从PID的原理出发,根据工程应用的具体情况,简化了PID控制器的参数,得到了简单的PID控制器参数。通过数值仿真对PID控制器参数进行了充分的讨论,明确了这一参数的最优取值范围及取值原则。通过成像实验验证了这种PID控制参数的正确性。     

基于增益调整型模糊PID的脉动真空灭菌器控制系统

针对目前脉动真空灭菌器控制效果不好而产生湿包的问题,结合Chien-Hrones-Reswicks整定算法,提出用模糊变增益PID的控制策略,控制器输入取控制舱内温度的偏差e和偏差变化率Δe。根据实际操作经验,加入模糊规则,输出取PID控制器2个参数的调整值,从而实现PID参数的在线自整定。在MATLAB/SIMULINK环境下进行了仿真实验,进行了传统PID控制与模糊变增益PID控制动态性能的仿真比较,结果表明采用模糊变增益PID控制策略可明显提高脉动真空灭菌控制系统的动态性能。.     

执行依赖启发式动态规划PMSM控制策略研究

永磁同步电机算法中的PID参数固定不变,自适应能力较差。近似动态规划具有自学习能力,能动态调整参数,增强系统的自适应能力。本文将近似动态规划中的代表性算法——执行依赖启发式动态规划与类PI网络相结合,根据环境反馈对各个策略进行评价,选取评价最优的策略在线调整动作网络参数,对永磁同步电机进行自适应最优控制。仿真结果表明,执行依赖启发式动态规划加PI控制算法在系统速度变化和负载变化过程中,动态效果和稳态精度优于传统PID控制。     

小潜艇供电系统全桥DC-DC开关电源智能优化设计

小型潜艇水下潜行采用蓄电池供电,通过全电力供电系统推进。以蓄电池为直流电源,在推进系统正常运转的状况下,开关电源电压输出值保持恒定。传统的PID控制器很难对全桥DC-DC开关电源进行精确控制,因此,将粒子群算法(PSO)、BP神经网络与径向基函数(RBF)神经网络与传统PID控制相结合,提出带有RBF神经网络辨识的PSO-BP-PID控制方法。通过神经网络在线自学习对PID三个参数在线调整,最终实现系统恒电压输出控制。仿真结果得出：带有RBF神经网络辨识的PSO-BP-PID控制算法可以很大的改善系统控制效果,同时使系统具有更好的在线调整能力。     

高炉送风系统力学行为的数字散斑相关法实验研究

研究高炉送风系统在燃烧、送风、切换状态时热风炉壳的力学性能。首次在热风炉炉壳测试中采用了高精度的数字散斑相关技术,利用自然光对热风炉壳进行了非接触式测量,得到了由于温度引起的轴向和环向的变形、应变及热应力等力学参量,光测结果与电测结果吻合较好。表明数字散斑相关测量技术应用于测量恶劣环境下力学参量有效,方法实用,较好地解决了热风炉壳的力学测试工作。     

废水余热回收热泵系统的节能控制方法研究

当今社会有大量废水余热没有回收利用。本文通过不同热回收系统间的对比分析,提出一种基于粒子群优化BP神经网络PID的废水余热回收热泵系统。利用能量平衡原理,建立了系统数学模型;运用粒子群优化BP神经网络PID控制方法,实现了PID参数的在线调整,实现了冷凝器风扇和循环泵的在线调节,最终实现了系统控制。利用Matlab/Simulink建立了控制系统仿真模型,结果表明:该控制方法与传统PID控制方法相比有效提高了系统响应速度和降低了系统超调量。以浴室为例进行实验验证,结果表明:与传统定频系统相比,采用传统PID控制方法可使系统功耗降低10.3%,而采用粒子群优化BP神经网络PID控制方法可使系统功耗降低14.1%。仿真与实验结果表明了所提出数学模型和控制方法的有效性。     

快速倾斜镜的模糊PID自适应控制器设计

介绍了一种快速倾斜镜系统。由于存在大气扰动、温度变化、环境干扰等非线性、不确定因素的影响,使用经典控制方法对这种变参数系统进行设计很难满足设计指标要求。在深入研究模糊理论的基础上,提出了模糊推理与经典PID相结合的自适应控制器设计方案,控制参数可以在线调整,解决了参数时变和建模不确定性的问题。仿真结果证明,模糊PID自适应控制器能很好地解决大气扰动、温度变化等环境干扰问题,改善了快速倾斜镜动态响应过程。研究结果为倾斜镜的快速控制提供了一种新的思路。     

超声速预混可燃气流的点火与燃烧

在激波风洞一激波管组合设备上开展了碳氢燃料超声速预混可燃气流的点火与燃烧实验研究。实验结果表明:利用激波对燃料进行预热,并以高温燃气作为引导火焰,可以有效缩短汽油空气超声速可燃混气的点火延迟时间,使之缩短到 0.2 ms以下。利用纹影照片对超声速燃烧流场结构作出了分析;研究了超声速预混可燃气流的温度以及当量比对超声速燃烧流场结构、点火与火焰传播特性的影响。     

轧钢加热炉燃烧工况在线测控系统

针对某大型钢厂轧钢加热炉系统在线实时性不强,采集数据不足,现场管理不便等问题,提出了构建加热炉燃烧工况在线测控系统。利用烟道气分析仪,在加热炉加热段增设多个燃烧气氛采集点,结合PLC和上位机组态软件,可以在线测量炉内不同区段残氧量与可燃物浓度,实现空气过剩系数的在线调整优化。同时,开发了节能量与氧化烧损两个模块,可用于实时估算可实现节能量与钢坯氧化烧损量。项目实施结果表明,炉燃烧工况在线测控系统可以实现加热炉内燃烧状况精确控制,有效降低燃气消耗。     

气体回流区分级着火试验研究

就回流区分级着火燃烧方式在气体燃料燃烧上的应用进行了一系列冷热态模拟试验和工业试验研究．比较了直流、钝体和开缝钝体喷口的出口速度、温度分布，以及在不同气体燃料热值时的稳焰能力。试验表明，开缝钝体喷口中缝小股射流进入喷口后低速回流区能稳定着火，进一步点燃主流，有效地形成回流区分级着火；开维钝体喷口的稳焰能力最强，特别适合低热值煤气燃烧。在大容量锅炉上进行了低热值高炉煤气燃烧的改造性工业试验，试验证明，开缝钝体燃烧器强化了低热值煤气的燃烧，有效地解决了锅炉煤气段燃烧强度不足以至锅炉尾部超温问题。     

LES of Laser Initiation of Combustion of Gaseous Fuel-Air Mixture

Large Eddy Simulation has been carried out to understand the laser initiation of combustion of lean hydrogen-air mixture in homogeneous isotropic turbulence. Initially, the blast wave from the breakdown zone sweeps out most the mixture surrounding the hot core zone at high velocity preventing formation of burning zone. The combustion initiates only if the core zone contains enough heat to sustain a steady flame thereafter.     

Numerical analysis of self-excited tangential combustion instability for an MMH/NTO rocket combustor

This study presented the numerical simulation of the tangential combustion instability in a hypergolic liquid bipropellant rocket thrust chamber, which applied fuel liquid film cooling method and unlike impinging injectors. The liquid spray was modeled using Lagrangian approach, while the gas was regarded as Euler phase. Stress-blended eddy simulation and finite rate/eddy–dissipation model were adopted to simulate the turbulent combustion process. Consistent with the experiment results, this work successfully simulated the transformation of tangential combustion instability from standing mode to spinning mode. The mean pressure, amplitude and frequency of limit cycle oscillation were in good agreement with the experiment. There was a detailed analysis about the flow field, Rayleigh index, and driving mechanism of the combustion instability. It was found that the oscillation began with hot spots of heat release rate due to the interaction between the spray of impinging injectors and cooling fuel jet. More than that, cooling fuel jet also contributed to drive the oscillation. In the standing mode, injectors in the inner and outer rings drive the oscillation together, while the spinning mode is mainly driven by injectors in the outer ring. The pressure wave is subsonic and its Mach number is close to 1. It was shown that the pressure wave contained a complex structure divided into three parts. This led to the in-phase of the pressure along the axial direction and the double-peak characteristic of the downstream pressure signal. Besides, a positive feedback closed-loop system associated with periodic oxidizer/fuel ratio was believed to sustain the combustion instability. The oscillation can be maintained when pressure, heat release and oxidizer/fuel ratio are coupled together. The analysis results indicate that rotating detonation is an implication to tangential combustion instability.     

Multiscale dynamic analysis of blast furnace system based on intensive signal processing

In this paper, the Hilbert-Huang transform method and time delay embedding method are applied to multiscale dynamic analysis on the time series of silicon content in hot metal collected from a medium-sized blast furnace with the inner volume of 2500?m3. The results provide clear evidence of multiscale features in blast furnace ironmaking process. Ten intrinsic mode functions (IMFs) are decomposed from the silicon content time series; the presence of noninteger fractal dimension, positive finite Kolmogorov entropy, and positive finite maximum Lyapunov exponent are found in some IMF components. In addition, the coupling of subscale structures of blast furnace system is studied using the dimension of interaction dynamics and a robust algorithm for detecting interdependence. It is found that IMF(3) is the main driver in the coupling system IMF(2) and IMF(3) while for the coupling system IMF(3) and IMF(4) neither subsystem can act as the driver. All these provide a guideline for studying blast furnace ironmaking process with multiscale theory and methods, and may open way for more candidate tools to model and control blast furnace system in the future.     

Feasibility of “intermittent” active control of combustion instabilities in liquid fueled combustors using a “smart” fuel injector

This paper describes an experimental investigation of the feasibility of an “intermittent” active control approach for suppressing combustion instabilities in liquid fueled combustors. The developed controller employs a “smart” fuel injector that can modify the spray properties in response to changes in combustor operating conditions. This action weakens or breaks up the coupling between the combustion process and combustor acoustic modes oscillations, thus preventing the excitation of large amplitude instabilities. This approach differs significantly from previously proposed active control methods, both in concept and implementation, as it requires only “intermittent” modification of the combustion process by a single control action as opposed to the continuous action required by most other active control methods. The “smart” fuel injector used in this study consisted of a double-staged, air-assisted atomizer in which counter swirling, primary (inner stage) and secondary (outer stage) air streams were supplied to the injector through separate sets of tangentially oriented orifices. Control of the ratio of air mass flow rates supplied to these two stages, by use of a diverter valve, resulted in significant changes in the spray shape and its axial, tangential, and radial velocity components. This variation in spray properties of the “smart” injector was characterized for different values of the inner to outer air flow rate ratio in cold flow tests with a PDPA system. These results were then correlated with the characteristics of the “intermittently” controlled combustor. Measured quantities included the instability amplitudes, axial dependence of the mean and oscillatory heat release amplitudes, and the characteristics of the recirculation zones, which were all shown to depend on the fuel spray properties. The results of this study demonstrate the feasibility of using “smart” fuel injectors with capabilities for varying the combustion process characteristics to reduce the amplitudes of detrimental combustion instabilities in real engines to acceptable levels.     

Minimum ignition energy and propagation dynamics of laminar premixed cool flames

Laminar premixed cool flames, induced by the coupling of low-temperature chemistry and convective-diffusive transport process, have recently attracted extensive interest in combustion and engine research. In this work, numerical simulations have been conducted using a recently developed open-source reacting flow platform reactingFOAM-SCT, to investigate the minimum ignition energy (MIE) and propagation dynamics of premixed cool flames in a 1D spherical coordinate. Results have shown that when ignition energy is below the MIE of regular hot flames, a class of cool flames could be initiated, which allow much wider flammability limits, both lean and rich, compared to hot flames. Furthermore, the overall cool flame propagation dynamics exhibit intrinsic similarity to those of hot flames, in that, they begin with an ignition kernel propagation regime, followed by two transition regimes, and eventually reach a normal flame propagation regime. However, a spherical expanding cool flame responds completely differently to stretch. Specifically, a regular outwardly propagating hot spherical flame accelerates with increasing stretch rate when the mixture Le < 1 and decelerates when Le > 1. However, it is found that a cool flame always tends to decelerate with increasing stretch rate regardless of mixture composition, exhibiting unique flame aerodynamic characteristic. This research discovers novel features of premixed cool flame initiation and propagation dynamics and sheds light on flame transition, spark-ignition system design, and advanced engine combustion control.     

高焓横向射流尾迹区掺混燃烧的数值特性

尾迹区作为横向射流流场的重要结构受到广泛关注，其掺混和燃烧特性对近壁面区域的流场特性有重要影响.文章在对仿真充分验证的基础上，采用Reynolds平均模拟方法对Ma=8飞行条件下高焓横向射流尾迹区中的掺混和燃烧特性进行了数值研究.探究了冷热流场尾迹区中的氢气掺混特性，冷态流场尾迹区中的激波结构对氢气分布产生一定影响，热态流场尾迹区中存在多种氢气掺混路径.V形回流区中的高浓度氢气对燃烧产生了一定的阻碍作用.定量测量了尾迹区中的火焰结构，尾迹区火焰的顶点位置随高度增加向下游线性移动，受射流主流影响，尾迹区火焰的展向宽度在距离壁面一定高度后开始增大.对冷热流场中的主要参数进行了对比，燃烧消耗了氢气使温度升高，但是尾迹区中的流动速度没有明显增加，燃烧放出的热量没有完全转化为流体的动能.