For the problem posed by closely spaced modes, this paper defined the MCC (modal correlation criterion) to measure the degree of correlation between close modes. It was proved that structures with certain features ten...For the problem posed by closely spaced modes, this paper defined the MCC (modal correlation criterion) to measure the degree of correlation between close modes. It was proved that structures with certain features tend to have closely clustered modes and the corresponding mode shapes highly correlated. With this understanding, the closed-form expressions for controllability and observability Grammians were adopted to analyze the impacts of actuator/sensor placement on the controllability/observability of highly correlated close modes. On this basis, the problem of actuator/sensor placement, when the optimization criterion is based on modal controllability/observability, was simplified. Moreover, the dimension of the control/measurement vector in independent modal space control for highly correlated close modes was proved to have the potential to be reduced, therefore fewer actuators and sensors were required in this dimension-reduced control strategy. Finally, the desirable vibration suppression for an example structure showed that the theory and methods of this paper were accurate and effective.展开更多
在多相电机驱动系统中,逆变器控制和调制算法引起的共模电压将会产生电磁干扰,从而影响系统正常工作、损坏电机定子绕组绝缘,降低电机使用寿命等;五相逆变器输出电流低次谐波将会导致定子铜耗增加,转矩脉动变大,影响电机控制性能。因此...在多相电机驱动系统中,逆变器控制和调制算法引起的共模电压将会产生电磁干扰,从而影响系统正常工作、损坏电机定子绕组绝缘,降低电机使用寿命等;五相逆变器输出电流低次谐波将会导致定子铜耗增加,转矩脉动变大,影响电机控制性能。因此,为抑制输出电流中所含的低次谐波分量,并减小共模电压,提出一种基于虚拟电压矢量的五相电压源逆变器空间电压矢量脉宽调制算法(virtual voltage vector based space vector pulse width modulation,V3-SVPWM)。首先,根据伏秒平衡原理,选择相邻4个大矢量按照特定占空比合成有效虚拟电压矢量,选择2个方向相反的大矢量合成虚拟零矢量。然后,使用虚拟电压矢量合成参考电压,计算过程简单,便于数字实现。最后,将所提算法与最近2矢量SVPWM(near-two vectors based space vector pulse width modulation,NTV-SVPWM)和最近4矢量SVPWM(near-four vectors based space vector pulse width modulation,NFV-SVPWM)进行仿真和实验对比研究,验证所提算法的正确性和有效性。展开更多
采用传统频域方法进行电力系统稳定器(power system stabilizer,PSS)参数设计时只考虑本机组的运行,忽视了电网的整体运行情况。为此,文章基于降阶选择模式分析法对PSS参数进行优化,形成了系统的降阶状态方程。通过计算状态方程特征根...采用传统频域方法进行电力系统稳定器(power system stabilizer,PSS)参数设计时只考虑本机组的运行,忽视了电网的整体运行情况。为此,文章基于降阶选择模式分析法对PSS参数进行优化,形成了系统的降阶状态方程。通过计算状态方程特征根与状态变量的相关性及灵敏度,确定了PSS的配置点。文中的方法不必计算系统全部特征根,所需的计算时间较少。针对新疆实际电网,文章还进行了PSS参数设计,确定了PSS的安装地点及安装机组,仿真结果表明文中的PSS抑制振荡的效果良好,验证了文中方法的正确性和有效性。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 10872028)
文摘For the problem posed by closely spaced modes, this paper defined the MCC (modal correlation criterion) to measure the degree of correlation between close modes. It was proved that structures with certain features tend to have closely clustered modes and the corresponding mode shapes highly correlated. With this understanding, the closed-form expressions for controllability and observability Grammians were adopted to analyze the impacts of actuator/sensor placement on the controllability/observability of highly correlated close modes. On this basis, the problem of actuator/sensor placement, when the optimization criterion is based on modal controllability/observability, was simplified. Moreover, the dimension of the control/measurement vector in independent modal space control for highly correlated close modes was proved to have the potential to be reduced, therefore fewer actuators and sensors were required in this dimension-reduced control strategy. Finally, the desirable vibration suppression for an example structure showed that the theory and methods of this paper were accurate and effective.
文摘在多相电机驱动系统中,逆变器控制和调制算法引起的共模电压将会产生电磁干扰,从而影响系统正常工作、损坏电机定子绕组绝缘,降低电机使用寿命等;五相逆变器输出电流低次谐波将会导致定子铜耗增加,转矩脉动变大,影响电机控制性能。因此,为抑制输出电流中所含的低次谐波分量,并减小共模电压,提出一种基于虚拟电压矢量的五相电压源逆变器空间电压矢量脉宽调制算法(virtual voltage vector based space vector pulse width modulation,V3-SVPWM)。首先,根据伏秒平衡原理,选择相邻4个大矢量按照特定占空比合成有效虚拟电压矢量,选择2个方向相反的大矢量合成虚拟零矢量。然后,使用虚拟电压矢量合成参考电压,计算过程简单,便于数字实现。最后,将所提算法与最近2矢量SVPWM(near-two vectors based space vector pulse width modulation,NTV-SVPWM)和最近4矢量SVPWM(near-four vectors based space vector pulse width modulation,NFV-SVPWM)进行仿真和实验对比研究,验证所提算法的正确性和有效性。
文摘采用传统频域方法进行电力系统稳定器(power system stabilizer,PSS)参数设计时只考虑本机组的运行,忽视了电网的整体运行情况。为此,文章基于降阶选择模式分析法对PSS参数进行优化,形成了系统的降阶状态方程。通过计算状态方程特征根与状态变量的相关性及灵敏度,确定了PSS的配置点。文中的方法不必计算系统全部特征根,所需的计算时间较少。针对新疆实际电网,文章还进行了PSS参数设计,确定了PSS的安装地点及安装机组,仿真结果表明文中的PSS抑制振荡的效果良好,验证了文中方法的正确性和有效性。
