介绍了单相级联型静止无功发生器(static var generator,SVG)的原理与控制系统结构,采用光纤隔离检测技术进行级联单元直流侧电压的测量。考虑光纤隔离检测延时,建立了基于瞬时能量平衡的直流侧电压外环控制数学模型,得到了基于比例积分...介绍了单相级联型静止无功发生器(static var generator,SVG)的原理与控制系统结构,采用光纤隔离检测技术进行级联单元直流侧电压的测量。考虑光纤隔离检测延时,建立了基于瞬时能量平衡的直流侧电压外环控制数学模型,得到了基于比例积分(proportional integral,PI)控制的传递函数,并进行了电压外环稳定性分析;建立了基于比例(proportional,P)控制的电流内环离散控制模型,分析得到其在离散域内稳定控制的充要条件。样机实验结果验证了所提稳定性分析方法的正确性。展开更多
Treating plant dynamics as an ideal integrator chain disturbed by the total disturbance is the hallmark of active disturbance rejection control(ADRC).To interpret its effectiveness and success,to explain why so many v...Treating plant dynamics as an ideal integrator chain disturbed by the total disturbance is the hallmark of active disturbance rejection control(ADRC).To interpret its effectiveness and success,to explain why so many vastly different dynamic systems can be treated in this manner,and to answer why a detailed,accurate,and global mathematical model is unnecessary,is the target of this paper.Driven by a motivating example,the notions of normality and locality are introduced.Normality shows that,in ADRC,the plant is normalized to an integrator chain,which is called local nominal model and locally describes the plant’s frequency response in the neighborhood of the expected gain crossover frequency.Locality interprets why ADRC can design the controller only with the local information of the plant.With normality and locality,ADRC can be effective and robust,and obtain operational stability discussed by T.S.Tsien.Then viewing proportional-integral-derivative(PID)control as a low-frequency approximation of second-order linear ADRC,the above results are extended to PID control.A controller design framework is proposed to obtain the controller in three steps:(1)choose an integrator chain as the local nominal model of the plant;(2)select a controller family corresponding to the local nominal model;and(3)tune the controller to guarantee the gain crossover frequency specification.The second-order linear ADRC and the PID control are two special cases of the framework.展开更多
Indium doped cadmium sulfide thin films （CdS：In） were produced by the spray pyrolysis technique on glass substrates. AC measurements were used to investigate the electrical properties of the films depending on Bric...Indium doped cadmium sulfide thin films （CdS：In） were produced by the spray pyrolysis technique on glass substrates. AC measurements were used to investigate the electrical properties of the films depending on Brick-layer model for polycrystalline materials. The measurements were performed at room temperature in the dark and room light in the frequency range from 20 Hz to 1 MHz using coplanar indium electrodes. The data were analyzed by using Bode plots for the impedance Z and dielectric loss tang with frequencyf It is found that the impedance has no dependence on frequency in the low frequency region but has 1/f dependence in the high frequency region. One dielectric loss peak is obtained, which means the presence of a single relaxation time, and hence the films are modeled by just one RC circuit which represents the grains. This means that there is just one conduction mechanism that is responsible for the conduction in the bulk, due to electronic transport through the grains. Real values of the impedance in the low frequency region and relaxation times for treated and as-deposited fihns were estimated.展开更多
文摘介绍了单相级联型静止无功发生器(static var generator,SVG)的原理与控制系统结构,采用光纤隔离检测技术进行级联单元直流侧电压的测量。考虑光纤隔离检测延时,建立了基于瞬时能量平衡的直流侧电压外环控制数学模型,得到了基于比例积分(proportional integral,PI)控制的传递函数,并进行了电压外环稳定性分析;建立了基于比例(proportional,P)控制的电流内环离散控制模型,分析得到其在离散域内稳定控制的充要条件。样机实验结果验证了所提稳定性分析方法的正确性。
基金This work was supported by the National Nature Science Foundation of China(Grant No.61733017).
文摘Treating plant dynamics as an ideal integrator chain disturbed by the total disturbance is the hallmark of active disturbance rejection control(ADRC).To interpret its effectiveness and success,to explain why so many vastly different dynamic systems can be treated in this manner,and to answer why a detailed,accurate,and global mathematical model is unnecessary,is the target of this paper.Driven by a motivating example,the notions of normality and locality are introduced.Normality shows that,in ADRC,the plant is normalized to an integrator chain,which is called local nominal model and locally describes the plant’s frequency response in the neighborhood of the expected gain crossover frequency.Locality interprets why ADRC can design the controller only with the local information of the plant.With normality and locality,ADRC can be effective and robust,and obtain operational stability discussed by T.S.Tsien.Then viewing proportional-integral-derivative(PID)control as a low-frequency approximation of second-order linear ADRC,the above results are extended to PID control.A controller design framework is proposed to obtain the controller in three steps:(1)choose an integrator chain as the local nominal model of the plant;(2)select a controller family corresponding to the local nominal model;and(3)tune the controller to guarantee the gain crossover frequency specification.The second-order linear ADRC and the PID control are two special cases of the framework.
文摘Indium doped cadmium sulfide thin films （CdS：In） were produced by the spray pyrolysis technique on glass substrates. AC measurements were used to investigate the electrical properties of the films depending on Brick-layer model for polycrystalline materials. The measurements were performed at room temperature in the dark and room light in the frequency range from 20 Hz to 1 MHz using coplanar indium electrodes. The data were analyzed by using Bode plots for the impedance Z and dielectric loss tang with frequencyf It is found that the impedance has no dependence on frequency in the low frequency region but has 1/f dependence in the high frequency region. One dielectric loss peak is obtained, which means the presence of a single relaxation time, and hence the films are modeled by just one RC circuit which represents the grains. This means that there is just one conduction mechanism that is responsible for the conduction in the bulk, due to electronic transport through the grains. Real values of the impedance in the low frequency region and relaxation times for treated and as-deposited fihns were estimated.
