作为抑制低频振荡最有效的手段之一,电力系统稳定器(power system stabilizer,PSS)在电力系统中得到了广泛的应用。现今国内最广泛采用的PSS是PSS2B,不过由于其自身结构问题,PSS2B对频率较低的区域间振荡模式抑制效果一般。新型多频段...作为抑制低频振荡最有效的手段之一,电力系统稳定器(power system stabilizer,PSS)在电力系统中得到了广泛的应用。现今国内最广泛采用的PSS是PSS2B,不过由于其自身结构问题,PSS2B对频率较低的区域间振荡模式抑制效果一般。新型多频段稳定器PSS4B有望解决这一问题,然而PSS4B的多参数多自由度给其参数整定带来了困难,提出了一种基于等高线控制器波特图(contoured controller bode,CCBode)的PSS4B稳定器迭代设计方法。PSS4B稳定器由带通滤波器和相位补偿器串联组成。使用空间搜索方法调整相位补偿器以确保PSS4B的相频特性被限制在可接受的范围内。CCBode曲线有助于调整带通滤波器的幅频特性,从而在较宽的频带范围内具有更好的稳定性能。对Kundur的四机两区系统的测试分析证明了该方法的有效性。展开更多
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
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
风机并网逆变器及送电系统的稳定性是大规模海上风力发电系统稳定运行的重要保证。提出一种考虑小干扰稳定的海上风电系统控制器参数优化设计方法。首先,利用谐波线性化原理推导了直驱风机并网逆变器、送端采用不控整流器的高压直流(dio...风机并网逆变器及送电系统的稳定性是大规模海上风力发电系统稳定运行的重要保证。提出一种考虑小干扰稳定的海上风电系统控制器参数优化设计方法。首先,利用谐波线性化原理推导了直驱风机并网逆变器、送端采用不控整流器的高压直流(diode-rectifier based HVDC,DR-HVDC)输电系统的序阻抗模型。然后,分析了风场经DR-HVDC并网互联系统的特点,讨论了稳定判据的适用性。进而,从控制器的角度,确定直驱风机并网逆变器控制系统的控制带宽和阻尼比的取值范围。并在此基础上,从系统的角度,综合考虑互联系统的右半平面零极点和控制参数等对阻抗比值的作用。最后,给出直驱风机并网逆变器的控制系统参数优化设计流程。基于Matlab/Simulink建立海上风电经DR-HVDC直流送出系统的时域仿真模型。仿真结果验证了理论分析的正确性和所提方法的有效性。展开更多
文摘作为抑制低频振荡最有效的手段之一,电力系统稳定器(power system stabilizer,PSS)在电力系统中得到了广泛的应用。现今国内最广泛采用的PSS是PSS2B,不过由于其自身结构问题,PSS2B对频率较低的区域间振荡模式抑制效果一般。新型多频段稳定器PSS4B有望解决这一问题,然而PSS4B的多参数多自由度给其参数整定带来了困难,提出了一种基于等高线控制器波特图(contoured controller bode,CCBode)的PSS4B稳定器迭代设计方法。PSS4B稳定器由带通滤波器和相位补偿器串联组成。使用空间搜索方法调整相位补偿器以确保PSS4B的相频特性被限制在可接受的范围内。CCBode曲线有助于调整带通滤波器的幅频特性,从而在较宽的频带范围内具有更好的稳定性能。对Kundur的四机两区系统的测试分析证明了该方法的有效性。
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。
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.
文摘风机并网逆变器及送电系统的稳定性是大规模海上风力发电系统稳定运行的重要保证。提出一种考虑小干扰稳定的海上风电系统控制器参数优化设计方法。首先,利用谐波线性化原理推导了直驱风机并网逆变器、送端采用不控整流器的高压直流(diode-rectifier based HVDC,DR-HVDC)输电系统的序阻抗模型。然后,分析了风场经DR-HVDC并网互联系统的特点,讨论了稳定判据的适用性。进而,从控制器的角度,确定直驱风机并网逆变器控制系统的控制带宽和阻尼比的取值范围。并在此基础上,从系统的角度,综合考虑互联系统的右半平面零极点和控制参数等对阻抗比值的作用。最后,给出直驱风机并网逆变器的控制系统参数优化设计流程。基于Matlab/Simulink建立海上风电经DR-HVDC直流送出系统的时域仿真模型。仿真结果验证了理论分析的正确性和所提方法的有效性。
