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1.
本文研究用DDC系统控制回路的衰减频率特性,规定系统在阶跃扰动作用时,其响应有合适的衰减比,使单位负荷变化下的误差和为最小作为最佳整定准则,导出了过程参数、采样周期等与数字PID控制器参数之间的关系式,並计算了一些图表,这些最佳整定数据,经仿真研究结果是满意的,这些公式为用计算机进行在线自整定控制提供了可能。  相似文献   

2.
在换热网络的运行过程中,其操作条件时常变化。针对过程系统安全平稳运行的基本要求,基于频域稳定性分析方法,得出影响过程系统动态性能与稳定性的关键点,提出一种换热网络旁路控制系统的设计方法。从频域的角度分析潜在旁路与被控变量之间的耦合关系,采用频域相对增益阵方法实现换热网络的旁路设计。并在此基础上,对设计的控制系统进行控制器参数设计,使换热网络控制系统满足一定的稳定裕度要求。结果表明,基于频域稳定性分析设计的换热网络旁路控制系统满足稳定裕度要求,其阶跃响应的绝对误差积分值较小,系统的动态性能更好。  相似文献   

3.
石油是世界上重要的能源,随着人们对石油的大量开采与利用,石油资源日益紧缺。因此,设计合适的基于钻机旋转系统的控制器,提高石油钻机的钻井效率,降低钻井成本,对于有效利用石油资源有着很重要的意义。目前,旋转系统的常规控制方法虽然得到广泛的运用,但其钻井效率比较低,钻井成本还比较高。针对上述问题,通过研究,本文所做的主要工作和研究结果如下:首先,论文建立了钻机旋转系统的数学模型,接着,对钻机旋转系统的数学模型进行了线性化处理。其次,分别设计了PID控制器、自适应控制器,随后对系统进行了仿真分析。应用PID控制器使阶跃响应超调量为零且不存在稳态误差,而应用自适应PID控制器不但具有PID控制器的所有优点而且使系统的快速性再次得到了提高。所以,使用自适应PID控制器进一步提高了钻井效率,得出了自适应控制规律的优越性。  相似文献   

4.
将叶片视为变截面悬梁,离散成任意段,每一段满足各向异性双向弯扭耦合振动微分方程,其解表作为两端节点10个自由度的函数,相邻段在同一截面内的节点位移由连续性条件联系,由此建立起求解叶片双向弯曲与扭转响应的传递函数,然后根据边界条件,得到一组仅含10个未知数的齐次方程,其非零解即是叶片各阶固有频率。相对有限元等其他数值方法,这种传递函数的解变量少,算法设计容易,求解速度快,精度高。基于该算法对一种大型叶片叶根段结构铺层优化后的频率特性进行了分析,结果显示,新设计方案不仅叶片重量显著降低,而且叶片刚度和频率特性完全满足使用要求。  相似文献   

5.
余世明  王海清 《化工学报》2004,55(3):396-401
在系统阶跃响应的基础上,根据最小绝对误差准则,用一个具有少量冗余参数的模型逼近实际系统的阶跃响应,提出了一种有约束冗余参数模型预测控制算法.由于冗余参数模型的参数比非参数模型少得多,多步预测和滚动优化的计算量大为减小.为了校正模型逼近带来的误差,引入了PID反馈校正环节,从而有效地克服了模型误差的不利影响.最后利用热交换过程的阶跃响应数据进行了计算机仿真研究,使算法的有效性得到验证.  相似文献   

6.
针对二阶加纯滞后对象的传递函数模型实现了一种辨识方法,该方法由系统的阶跃响应采样数据构造非线性方程组,再通过最小二乘法估计系统参数,利用该方法分别对换热器和加热炉出口温度进行模型辨识,具备较高的辨识精度,验证了该方法的有效性;同时将该方法辨识得到的换热器出口温度模型应用在内模控制方案中,取得了较好的控制效果,为其工业应用提供了可行性方案。  相似文献   

7.
在基元过程序列结构判识的基础上,以傅立叶变换红外光谱仪(FTIR)气体池作为检测器,采用动态响应技术,进行了合成甲醇过程瞬态动力学的实验研究,得到了微型反应器尾气中各主要物种的浓度对反应器进料浓度阶跃变化的动态响应数据。基于瞬态速率模型对实验数据的拟合,得到了由H_2/CO/CO_2合成甲醇初步的瞬态动力学关系。  相似文献   

8.
在基元过程序列结构判识的基础上,以傅立叶变换红外光谱仪(FTIR)气体池作为检测器,采用动态响应技术,进行了合成甲醇过程瞬态动力学的实验研究,得到了微型反应器尾气中各主要物种的浓度对反应器进料浓度阶跃变化的动态响应数据。基于瞬态速率模型对实验数据的拟合,得到了由H_2/CO/CO_2合成甲醇初步的瞬态动力学关系。  相似文献   

9.
以螺杆挤出机温控系统的扰动多、非线性、时变以及大滞后的特性,研究得到了智能化的控制算法,对于现场无法充分预料的情况,这种温度控制系统能够发挥重要的作用。使用Zig Bee无线传感技术可实现温度监控的远程操作,提升检测效率和水平。对远程无线温度控制系统的硬件系统进行了设计,对CC2430射频主控芯片的外围电路、温度传感电路以及温度控制电路进行设计。针对螺杆挤出机温度控制系统进行实例分析,研究结果表明:使用常规PID控制器,在阶跃信号和脉冲干扰信号作用下,系统超调量和稳定时间不能够满足螺杆挤出机温度控制的要求。使用模糊PID控制器,相比常规PID控制器的超调量和稳定时间要明显增强。以尼龙6/Ca Cl2复合材料挤出为例,分别使用常规PID控制算法和模糊控制算法进行对比分析,研究温度控制精度对产品成型质量的影响。在模糊控制算法下,三种产品(温度设置分别为240,260,280℃)的缺口冲击强度合格率比较使用常规PID控制算法时提高了6.87%,弯曲应力合格率、断裂伸长率合格率、拉伸强度合格率分别提高了8.67%,9.33%,8.77%。  相似文献   

10.
根据从新型干法水泥分解炉温度控制过程中采集的实测数据,选取从过渡工况到动态稳定工况过程中的典型数据段,用阶跃响应法建立分解炉温度控制过程稳态工作点附近的二阶惯性加纯滞后数学模型;以分解炉出口温度偏差及偏差变化率为输入变量,尾煤变化量为输出变量,使用MATLAB的Fuzzy Logic工具箱设计二维模糊控制器,并在稳态阶...  相似文献   

11.
The thermal dynamics of a top-loading drum dryer is studied with a view of deriving the transfer function for the thermal process involved. The drum which initially operates at a steady state, is subjected to a step change in the steam pressure and the response of the temperature of the outer surface of the drum is recorded. The normalised time domain response of the temperature T is analysed using the least squares method to a non-linear function. The time domain response is also transformed into the frequency domain using Fourier transforms and the transfer function is derived.  相似文献   

12.
A new process identification method is proposed to estimate the frequency responses of the process from the activated process input and output. It can extract many more frequency responses and guarantees better accuracy than the previous describing function analysis algorithm. In addition, the proposed method can be applied to the case that the initial part of the activated process data is periodic (cyclic‐steady‐state), which is not possible with any previous nonparametric identification methods using the modified Fourier transform or Fourier analysis. Furthermore, it can incorporate all the cases in which either the initial part is steady‐state and the final part is cyclic‐steady‐state or both the initial and final parts are steady‐state. © 2010 American Institute of Chemical Engineers AIChE J, 2010  相似文献   

13.
根据相关国家标准中的电能质量的5个指标,从测量精度和软硬件实现难度两方面因素考虑,确定各指标的测量方法。采用快速傅里叶变换(FFT)分析电网谐波,通过跟踪电网频率,实现准同步采样,解决FFT的频谱泄露问题。利用FFT的运算结果,在频域里计算出电压电流的有效值、电压偏差、功率和功率因数、三相不平衡度。闪变的测量采用IEC的测量原理,并对其作了修正,通过双线性变换,实现了闪变测量的数字化。  相似文献   

14.
电加热器温度仿人智能多模型控制   总被引:2,自引:1,他引:1  
对于实验室电加热器温度一类具有大范围工况、非线性和大惯性特性的对象,用单一模型无法准确描述模型特征,影响控制精度;采用常规控制策略无法解决响应快速性与系统稳定性的矛盾。针对上述问题,利用MATLAB辨识工具箱分别在大幅升温、大幅降温、小幅升温、小幅降温四种工况下对模型参数进行辨识,得到对象模型集;根据仿人智能思想将控制分为"全压加速-零制动-稳态调节"三个阶段,各控制阶段根据对象特性选取相应模型,并利用辨识模型获得控制器参数和切换点,在稳态调节阶段针对升温和降温的正反模型特性引入多模型加权控制方法。在加热器装置上实验的结果表明,该方法控制精度高,系统响应速度和稳定性都有了很大提升。  相似文献   

15.
A new nonparametric process identification method is proposed to obtain the frequency response model from given process input and output data. The proposed algorithm can estimate exact models for all desired frequencies. It is applicable to various process conditions (initial/final steady‐state, initial steady‐state/final cyclic‐steady‐state, and initial/final cyclic‐steady‐state) and requires a smaller amount of memory than previous methods. Also, it provides the exact models even in the presence of a static disturbance and shows an acceptable robustness to measurement noises. © 2011 American Institute of Chemical Engineers AIChE J, 2011  相似文献   

16.
Frequency response of the nonisothermal viscoelastic film blowing process to the ongoing sinusoidal disturbances has been investigated using transient simulation techniques. Of the many state variables exhibiting resonant peaks with the input frequency, amplitude ratio of the film cross‐sectional area at the freezeline height has been used as an indicator of the process sensitivity. The effects of operating conditions and viscoelasticity on the sensitivity have been scrutinized around the middle point of three multiple steady states under the given conditions. The sensitivity results have been interpreted through their correlation with results from linear stability analysis. Increasing draw ratio generally makes the system more sensitive to sinusoidal disturbances, whereas the cooling induces more sensitive or less sensitive system, according to the location of a steady state. Also, the viscoelasticity makes the system of extensional thickening fluids more sensitive at low Deborah number and less sensitive at high Deborah number. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

17.
A continuous stirred tank reactor subject to random fluctuations in flow rate and inlet temperature was simulated on a hybrid computer. The stochastic response of the reactor about unique stable deterministic steady states was studied as a function of the damping coefficient and response time of the deterministic system and the power spectrum of the stochastic input. It was found that the stochastic response could be classified into categories similar to those used for forced periodic systems according to the relationship between the deterministic system response time and the 90% cut-off frequency of the stachastic input. The nature of the stochastic response is predictable for relatively low frequency inputs but unexpected results may occur at intermediate frequencies. The magnitude of reactor state fluctuations was seen to be dependent on the deterministic damping coefficient. The distribution of reactor states was studied as a function of input process variance and it was found that the distribution can become bimodal even when the associated deterministic steady state is unique.The concept of stochastic stability is discussed and several practical stochastic stability definitions are proposed. The stochastic stability of the random systems was seen to be well described by the stochastic regions of operation predicted by the input process power spectrum and the deterministic system response time. The input variance levels necessary to produce stochastic instability can be estimated in the Quasi Steady region of operation. It was found that exposure of an autonomous limit cycle about a unique unstable deterministic steady state to high frequency random inputs may lead to effective stabilization.  相似文献   

18.
武心壮  邱健  郭丹丹  邱斌斌  严俊杰 《化工进展》2014,33(10):2588-2591,2633
在稳定射流区,对饱和蒸汽在过冷水中浸没射流凝结引起的压力振荡特性进行了研究,测量得到了不同汽水参数下的压力振荡特性。通过FFT方法得到了压力振荡的主频,并分析了蒸汽质量流率和水温对压力振荡主频的影响规律,蒸汽射流凝结换热特性决定了压力振荡主频随着蒸汽质量流率和水温的增大而降低。同时,利用先前学者提出的公式并引入量纲为1的蒸汽质量流率和凝结势给出了计算主频的实验关联式,结果表明在本实验参数范围内计算值与实验值具有相同的变化趋势,且吻合的较好,误差在±8%以内。  相似文献   

19.
THERMAL DYNAMICS OF A DRUM DRYER   总被引:1,自引:0,他引:1  
The thermal dynamics of a top-loading drum dryer is studied with a view of deriving the transfer function for the thermal process involved. The drum which initially operates at a steady state, is subjected to a step change in the steam pressure and the response of the temperature of the outer surface of the drum is recorded. The normalised time domain response of the temperature T is analysed using the least squares method to a non-linear function. The time domain response is also transformed into the frequency domain using Fourier transforms and the transfer function is derived.  相似文献   

20.
A parametric identification technique via closed-loop testing using frequency response techniques is presented in this study. Under an operation of proportional control, a single dynamic test (such as an arbitrary pulse or step change) in the set point was introduced to the system. The closed-loop transients could numerically be translated into frequency response data by Fourier integral transforms, and the parameters of a given process model were then be obtained by a least-squares fit in the frequency domain based on Parseval's theorem. This identification technique could apply not only for self-regulating processes but also for integrating or open-loop unstable processes. Furthermore, the proposed technique was also extended to the controller settings for the feedforward-feedback control system. Simulation results demonstrated that the proposed technique could yield good model parameters and can be applied in many different types of processes.  相似文献   

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