When the parameters of the system change abruptly, a new multivariable adaptive feedforward decoupling controller using multiple models is presented to improve the transient response. The system models are composed of...When the parameters of the system change abruptly, a new multivariable adaptive feedforward decoupling controller using multiple models is presented to improve the transient response. The system models are composed of multiple fixed models, one free-running adaptive model and one re-initialized adaptive model. The fixed models are used to provide initial control to the process. The re-initialized adaptive model can be reinitialized as the selected model to improve the adaptation speed. The free-running adaptive controller is added to guarantee the overall system stability. At each instant, the best system model is selected according to the switching index and the corresponding controller is designed. During the controller design, the interaction is viewed as the measurable disturbance and eliminated by the choice of the weighting polynomial matrix. It not only eliminates the steady-state error but also decouples the system dynamically. The gtobel convergence is obtained and several simulation examples are presented to illustrate the effectiveness of the proposed controller.展开更多
以逆变器为能量接口的并网系统振荡问题频繁发生,为改善逆变器的抗扰能力通常在控制结构中引入电压前馈环节,然而前馈控制会显著改变逆变器的运行特性,进而影响系统的稳定性。因此,该文研究了前馈控制对不同振荡主导环节的影响并提出了...以逆变器为能量接口的并网系统振荡问题频繁发生,为改善逆变器的抗扰能力通常在控制结构中引入电压前馈环节,然而前馈控制会显著改变逆变器的运行特性,进而影响系统的稳定性。因此,该文研究了前馈控制对不同振荡主导环节的影响并提出了一种附加前馈振荡抑制措施。首先,建立了逆变器的频率耦合阻抗模型,分析了前馈控制对不同频段阻抗特性的影响。其次,明确了不同频段振荡的主导环节,进而分析了计及前馈控制的振荡主导环节与电网交互作用引发系统失稳的机理。然后,基于不确定与扰动估计器提出了锁相环频段的振荡抑制措施,将锁相环的扰动作为附加前馈环节补偿到q轴电流环,可以有效改善该频段的阻抗特性进而抑制振荡。结果表明,比例系数为1的电压前馈控制和基于不确定与扰动估计器(uncertainty and disturbance estimator,UDE)的附加前馈控制可以有效提升电流环和锁相环频段的稳定性,通过时域仿真验证了所提方法的有效性。展开更多
A composite control strategy for the precalciner exit temperature in cement kiln is introduced based on a mathematical model. In this model, the raw meal flow, coal powder flow and wind flow are taken as three inpu...A composite control strategy for the precalciner exit temperature in cement kiln is introduced based on a mathematical model. In this model, the raw meal flow, coal powder flow and wind flow are taken as three input variables, the clinker fow and exit teperature of cement kiln are output variables, and other influencing factors are considered as disturbance. A composite control system is synthesied by integrating self learning PID, fuzzy and feedforward function into a combined controller, and the arithmetics for the self learning PID controller, fuzzy controller and feedforward controller are elaborated respectively. The control strategy has been realized by software in real practice at cement factory. Application results show that the composite control technology is superior to the general PID control in control effect, and is suitable to the industrial process control with slow parameter variation, nonlinearity and uncertainty.展开更多
文摘When the parameters of the system change abruptly, a new multivariable adaptive feedforward decoupling controller using multiple models is presented to improve the transient response. The system models are composed of multiple fixed models, one free-running adaptive model and one re-initialized adaptive model. The fixed models are used to provide initial control to the process. The re-initialized adaptive model can be reinitialized as the selected model to improve the adaptation speed. The free-running adaptive controller is added to guarantee the overall system stability. At each instant, the best system model is selected according to the switching index and the corresponding controller is designed. During the controller design, the interaction is viewed as the measurable disturbance and eliminated by the choice of the weighting polynomial matrix. It not only eliminates the steady-state error but also decouples the system dynamically. The gtobel convergence is obtained and several simulation examples are presented to illustrate the effectiveness of the proposed controller.
文摘以逆变器为能量接口的并网系统振荡问题频繁发生,为改善逆变器的抗扰能力通常在控制结构中引入电压前馈环节,然而前馈控制会显著改变逆变器的运行特性,进而影响系统的稳定性。因此,该文研究了前馈控制对不同振荡主导环节的影响并提出了一种附加前馈振荡抑制措施。首先,建立了逆变器的频率耦合阻抗模型,分析了前馈控制对不同频段阻抗特性的影响。其次,明确了不同频段振荡的主导环节,进而分析了计及前馈控制的振荡主导环节与电网交互作用引发系统失稳的机理。然后,基于不确定与扰动估计器提出了锁相环频段的振荡抑制措施,将锁相环的扰动作为附加前馈环节补偿到q轴电流环,可以有效改善该频段的阻抗特性进而抑制振荡。结果表明,比例系数为1的电压前馈控制和基于不确定与扰动估计器(uncertainty and disturbance estimator,UDE)的附加前馈控制可以有效提升电流环和锁相环频段的稳定性,通过时域仿真验证了所提方法的有效性。
文摘A composite control strategy for the precalciner exit temperature in cement kiln is introduced based on a mathematical model. In this model, the raw meal flow, coal powder flow and wind flow are taken as three input variables, the clinker fow and exit teperature of cement kiln are output variables, and other influencing factors are considered as disturbance. A composite control system is synthesied by integrating self learning PID, fuzzy and feedforward function into a combined controller, and the arithmetics for the self learning PID controller, fuzzy controller and feedforward controller are elaborated respectively. The control strategy has been realized by software in real practice at cement factory. Application results show that the composite control technology is superior to the general PID control in control effect, and is suitable to the industrial process control with slow parameter variation, nonlinearity and uncertainty.
