阻尼振荡

The static model of torsion joint is based on that of bending joint. The effects of structure parameters inside air pressure, initial angle, rube average radius, rube shell thickness on the turning angle are analyzed and the following conclusions are drawn: the relationship between the angle of torsion joint and the inside air pressure is basically linear, the angle of torsion joint increases with the initial angle and rube average radius, the angle of torsion joint decreases while the rube shell thickness increases. The kinetic equation is built for torsion joint. Simulating experiment implies that the time of inflating and deflating process is extremely shorter than that of kinetic process. So the pneumatic process can be ignored in actual system design and control. The factors that affect the dynamic features of torsion joint, such as shell thickness of rubber tube, average radius, initial angle, connector's outlet area, moment of inertia and viscous damping coefficient, are analyzed and the following conclusions are drawn: the change of rube shell thickness has no effects on the dynamic process of FPA inside air pressure while greatly affects the turning angle of torsion joint; when the rube shell thickness is small, the torsion joint has a bigger turning angle, no overshoot and long risetime, when the shell thickness is big, the turning angle of torsion joint is small, but has high response speed, overshoot and low shock; when the rube average radius increases, the turning angle of torsion joint increases and the overshoot increases too; when the initial angle of torsion joint is big, the turning joint is big, the overshoot is small and shock is low, but the risetime is big; the connector's outlet area affects the dynamic process of FPA inside air pressure greatly, but has no effects on the dynamic process of turning angle; moment of inertia and viscous damping coefficient have no effects on the dynamic process of FPA inside air pressure, but affect the dynamic process of turning angle greatly.

在弯曲关节模型推导的基础上，建立扭转关节的静态模型，并分析了扭转关节内腔压力，初始转角，橡胶管平均半径，橡胶管壁厚等参数对关节转角的影响，得出扭转关节的转动角度与充入FPA内腔的压缩气体压力之间基本呈线性关系，扭转关节的转角随初始角度和橡胶管平均半径的增大而增大，扭转关节的转角随橡胶管壁厚的增大而减小的结论；建立了扭转关节的动力学方程，仿真实验表明FPA的充放气过程与扭转关节的动力学过程相比时间极短，在实际系统设计和控制过程中可以忽略不计；分析讨论橡胶管壁厚，平均半径，初始角度，气体节流口面积，转动惯量，粘性阻尼系数等因素对扭转关节动态特性的影响，得出橡胶管初始壁厚的变化对扭转关节FPA内腔压力的动态响应几乎没有影响而对关节转角的响应曲线影响比较明显，壁厚较小时，关节可以得到较大的转角，并且转角的响应曲线没有超调，但上升时间长，壁厚较大时，关节转角变小，响应加快，但是有超调和轻微振荡现象，橡胶管平均半径越大，得到的关节转角越大，但是转角响应的超调量也随之增大，FPA的初始角度越大，关节的转角越大，并且超调量减小，振荡减弱，但是上升时间增大，管接头出口面积的大小对关节FPA内腔压力的建立过程影响较大，但对关节转角的动态响应几乎没有影响，转动惯量和粘性阻尼系数对FPA内腔压力的动态过程几乎没有影响而对扭转关节转角有较大影响等结论。

In order to improve the reliability of the nuclear Generating Sets and the stabilization of the power system, prevent the long time low frequency oscillation caused by the disturbed of the outside electrical net, assured improving the stabilization margin of the nuclear generating sets in the precondition of enough transient stability, validate the sensitivity of the parameter to the damping of Generating Sets of the MEC5220 digital excitation adjustor produce in Japan that used in the Second Project of Qinshan Nuclear Power Plant, confirm the parameter rationality of the digital excitation adjustor, optimize the parameter of PSS, in this paper, we put up a in-depth study to the principle of MEC5220 digital adjustor produce in Japan by the PSS/E software that develop by the PTI Company in the USA, completed the modeling of the excitation adjustor, PSS, generator, excitor, described the performance of this excitation adjustor, analyzed the essential reason that caused the low frequency oscillation, illuminated the factor that influence the damping characteristic of the MEC5220 digital excitation adjustor. Based on model and emulate, this paper optimized the primary parameter of the excitation adjustor, make a reasonable regulation to the PSS parameter.

为提高核电机组的运行可靠性和接入系统的安全稳定性，防止在外电网的干扰下核电机组发生长时间的低频振荡，保证机组在暂态稳定的前提下提高其稳定裕度，验证秦山核电二期核电机组所配日产MEC5220型数字式励磁调节器参数对机组阻尼的灵敏性，确定数字式励磁调节器的参数的合理性，优化PSS整定参数，本文利用美国PTI公司研发的PSS／E软件对日产MEC5220型数字调节器的原理进行进行了深入细化的研究，完成了励磁调节器、PSS、发电机、励磁机的建模，描述了该型励磁调节器的性能，分析了产生低频振荡的根本原因，阐明了影响阻尼特性的因素。

The first is refered to the vibration model with retardation for the market equilibrium price, where the knowledge of the second order linear ordinary differential equation is used.

第一个是研究市场调节下平衡价格的阻尼振荡模型，使用了二阶线性常系数微分方程的课程知识；第二个是在引进社会福利因素时商品的最优定价模型，使用了定积分和微分法的课程知识。

The first is refered to the vibration model with retardation for the market equilibrium price, where the knowledge of the second order linear ordinary differential equation is used. The second is refered to the optimal pricing model of the price under the frame of the social welfare, where the concept of the definite integral is exploited.

第一个是研究市场调节下平衡价格的阻尼振荡模型，使用了二阶线性常系数微分方程的课程知识；第二个是在引进社会福利因素时商品的最优定价模型，使用了定积分和微分法的课程知识。

The transmission capability of AC lines is sometimes limited by undamped oscillation s under "steady-state" conditions.

有时，交流线路的输电容量受到"稳态"条件下非阻尼振荡的限制。

The transmission capability of AC lines is sometimes limited by undamped oscillations under "steady-state" conditions.

有时，交流线路的输电容量受到"稳态"条件下非阻尼振荡的限制。

But in practical operating, overvoltage caused by reignition of the vacuum switching device frequently appears, and it result in damage of the capacitor bank or the switchgear itself. Ensuring the switchgear against reignition and installing a protective device are two main approaches to avoid the phenomenon. In this paper, a study on overvoltage caused by reignition due to capacitor bank switching with the vacuum switching device and its preventive measures are carried out. The main work which has been done and researches are as follows: 1. The producing mechanism of overvoltage and its influence factor are analyzed. It is pointed out that single-phase reignition is the main reason for damage of the switchgear and two-phase reignition is the main reason for damage of the capacitor bank,so overvoltage of single-phase reignition and two-phase reignition are the emphases of prevention. 2. Analysis of the special working condition of the operating switch for capacitor bank is carried out. It indicates that the vacuum switching device is difficult to realize no-reignition under this operation condition, so it is more practical to adopt protection devices. 3. Analyses of protection effect of RC and MOA and their shortages are carried out. It shows that the two methods can only restrain effectively overvoltage caused by single-phase reignition, and they cannot protect the capacitor bank when reignition of two-phase occurs. 4. The operation principle of G-R damping device is analyzed and discussed emphatically.

本文针对真空开关投切电容器组时因重燃而产生的过电压及其防治措施进行了研究，所开展的主要工作和研究结果如下： 1、对过电压的产生机理及其影响因素进行了分析，指出单相重燃是导致开关设备损坏的主要原因，而两相重燃则是导致电容器组损坏的主要原因，因此单相重燃和两相重燃过电压是防护的重点； 2、对电容器组操作开关的特殊运行条件进行了分析，指出在这种运行条件真空开关难于实现不重燃，因此采用保护装置更具有现实意义； 3、对RC与MOA的保护效果和存在的不足进行了分析，指出这两种方法均只能有效抑制单相重燃过电压，而不能在发生两相重燃时保护电容器组； 4、重点对G-R阻尼装置的工作原理进行了分析和讨论，指出该装置接入后线路中将会出现两种频率的高频振荡，而电容器组上的过电压是由这两种振荡共同决定的； 5、根据对上述两种振荡的分析指出存在一个最佳电阻值使得过电压最低，并提出了电容器组电压和最佳电阻值的近似求解方法； 6、使用电气暂态分析软件MATLAB对G-R装置的保护效果进行了仿真计算，证实该装置确实可以有效抑制重燃时的电容器组过电压； 7、根据仿真与近似计算结果的偏差提出了近似计算的修正方法，经过修正后的过电压计算结果与仿真结果吻合较好； 8、对G-R装置中放电装置G与阻尼电阻R的要求进行了分析，指出采用编织电阻和真空间隙可能是最佳选择。

Based on two kinds of control strategies of VSR under unbalanced grid condition,the introduction of a new VSR control strategy featuring undamped -oscillation that simplifies the controller structure and effectively improves VSR"s performance under unbalanced grid condition.· A systematic description of the state switching in trilogic PWM signal generation of three-phase CSR by using the conversion between bilogic and trilogic switching functions.· Referenced to the CSR"s trilogic PWM signal generation, an approach to achieve low-stress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss.

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；·通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；·结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

Referenced to the CSR's trilogic PWM signal generation, an approach to achieve lowstress natural commutation of switching devices by reshuffling the vector composition sequence, resulting reduced switching loss. With the background of and well instanced by the Xinjiang Autonomous Region's Key SciTech Project"Solar Photovoltaic grid-connected inverter", the dissertation work implemented the new approach of a grid-connected PV inverter that was of single-phase VSR topology and with MPPT .

在研究了两类电网不平衡时的VSR控制策略基础上，提出了一种新型的基于无阻尼振荡控制器的VSR不平衡控制策略，在简化控制结构的同时，有效地改善了电网不平衡时的VSR控制性能；通过二、三值逻辑开关函数间的转换，系统地描述了三相CSR三值逻辑PWM信号发生中的状态切换；结合三相CSR三值逻辑PWM信号发生规律，提出了通过调整矢量合成顺序而使功率管获得自然换相的低电压应力SVPWM控制，从而有效地降低了功率管的开关损耗。

The results show that the relationship betweentotal potential energy and time step exhibits periodic characteristic when sigma-3symmetric twist grain boundary model and sigma-3 tilt grain boundary model slide atOK. But for sigma-13 asymmetric tilt grain boundary, the relationship between totalpotential energy and time step exhibits damp surge characteristic.

结果发现，∑3对称扭转晶界模型与∑3对称倾侧晶界模型在0K滑动时，系统的势能与计算步数之间的关系曲线呈现周期性变化的规律，而∑13非对称倾侧晶界模型系统的势能与计算步数之间的关系却呈现阻尼振荡特征的变化规律。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。