矩

Aimed at the problem of choosing the initial value when the Newton method is used to compute the controlling unstable equilibrium point, a practical and rigorous solving scheme was presented: by identifying the controlling load bus of the given fault, and using the Thevenin equivalent circuit to represent the rest of the system at the state of the post disturbance stable equilibrium point, using the steady equivalent circuit to represent the induction motor in composite load, and then using the torque characteristics of induction motor, a point near the CUEP is gained to be the initial value. The second order normal forms was used to approximate the stable manifold of CUEP, and the local approximating boundary of the region of attraction of the post disturbance stable equilibrium point was gained. Then just by simulating the state of the system at the fault clearing time, the transient voltage stability of the system could be determined.

针对采用牛顿法求取故障后系统主导不稳定平衡点(controlling unstable equilibrium point，CUEP)存在的初值选取难题，提出一种实用但不失严谨的解决方案：通过识别给定故障的主导负荷母线，对主导负荷母线以外系统由故障后稳定平衡点处的状态进行戴维南等值，对负荷中感应电动机部分采用其稳态等值电路，再由感应电动机的转矩特性求得CUEP附近的一个点作为近似的CUEP，以此为迭代初值可靠求得CUEP；采用二阶正规型来近似CUEP的稳定流形的方法求得近似的局部吸引域边界；由仿真得到故障清除时刻系统的状态并根据该状态是否位于吸引域内判断系统的暂态电压稳定性。

This thesis introduces many kinds of visualization methods including histogram, scatter plot, cloud plot, parallel graph, star chart, and U-matrix by SOM .

本文实现多种可视化的方法，包括直方图、散点图、云图、平行线图、星图和 SOM 之 U 矩阵法。

Symmetrical components method is employed in the analysis of the asymmetrical circuit system, the value of the starting resistance is calculated preliminarily, and then, well and truly determined by computer simulation.

仿真结果表明，三相异步电动机定子一相或两相串联电阻起动，可以有效地限制起动电流和起动转矩，延长起动时间，适合于某些生产机械对起动的要求。

The test results indicated that the precision of thetorque Sensor on the cool-starting resistance torque and starting rotate speed of the diesel engine can respectively reach 0.6 %and 0.5%, which completely satisfy the cool-starting requirements of the diesel engine at low temperature; the performance curvesof the cool-starting resistance torque for diesel engine on the condition of the different low temperature were accurately obtained,and the variation rules of the performance parameters about the starting rotate speed and the starting power for the diesel enginewere estimated, whichwas the academic basis on the optimalmatching of the cool-starting parts about the diesel engine, the elec-tromotor and storage battery and so on.

结果表明：转矩传感器用来测试低温起动阻力矩和转速的准确度分别达到0·6%、0·5%，满足柴油机低温起动系统测试指标的要求；准确地测得了在不同转速和不同温度下的阻力矩性能曲线，同时也能判断出柴油机的起动转速和起动功率等性能参数的变化趋势及规律，为柴油机、电动机和蓄电池等低温起动部件的优化匹配提供了理论依据。

In order to solve the problem of serious fluctuation of starting current in traditional control scheme, the author puts forward a new kind of starting method which can limit voltage value to achieve the goal of reducing fluctuation of the current by using zero voltage vector during the stage of starting.

文章分析了异步电动机直接转矩控制系统的工作原理及起动过程，针对传统控制方案存在起动电流波动严重的问题，提出一种通过在起动过程增加零电压矢量的方法限制电压值，达到减小电流波动的目的，对此进行了仿真研究，仿真结果表明该方法是有效的。

In the process of calculation, the stator terminal voltage was taken as restriction condition, and the starting current is iterated to obtain the starting current and starting torque under the rated voltage.

在计算过程中，以定子端电压为约束条件，对定子起动电流进行了迭代计算，得到了额定电压下的起动电流和起动转矩。

According to characteristics of high pressure ammonia pump,was mechanical torque converters were superseded by transducers to realize full voltage starting and electric-dazzling preventins,and save electricity was above 20%.

针对高压氨泵的工艺特点，用变频器取代了机械变矩器调速，实现了抗压启动和防晃电功能，并且节能20%以上。

In the process of numerical computation of electromagnetic field, primary ending voltage is taken as constraint condition, primary starting current is iterated, and stating current and starting torque at rated voltage is obtained.

在电磁场的数值计算过程中，以初级端电压为约束条件，对初级起动电流进行了迭代计算，得到了额定电压下的起动电流和起动转矩，最后把正弦电磁场计算结果与实测结果进行了对比，表明直线感应电动机起动性能的计算结果满足工程实际的需要。

In this paper, according to the theory of electromagnetic fields, firstly, electromagnetic field of large and medium asynchronous motor is calculated from the angle of coupled fields, secondly, the end voltage of the stator is taken as constraint condition and starting current in stator is iterated in the numeral computation process, finally starting current and starting torque at rated voltage are gained, and by comparing calculation results with test results ,starting performance of large and medium asynchronous motor meet the demand of project practice.

本文根据电磁场理论，从耦合场的弱耦合角度首先计算了大中型异步电动机的电磁场，在电磁场的数值计算过程中，以定子端电压为约束条件，对定子起动电流进行了迭代计算，得到了额定电压下的起动电流和起动转矩，并把正弦时变场计算结果与实测结果进行对比，表明大中型异步电动机的起动性能的计算结果满足工程实际的需要。

Find a relation between the maximum pressure and the pressure at any point · Apply the condition of statical equilibrium to find the actuating force, the torque, and the support reactions.

寻找关系最大压力和压力，在任何一点·申请条件的静力平衡，以寻找驱动力，转矩，及支持的反应。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。