Frequency support capability of variable speed wind turbine based on electromagnetic coupler

In the variable speed wind turbine based on electromagnetic coupler (WT-EMC), a synchronous generator is directly coupled with grid. So like conventional power plants WT-EMC is able to support grid frequency inherently. But due to the reduced inertia of synchronous generator, its frequency support capability has to be enhanced. In this paper, the frequency support capability of WT-EMC is studied at three typical wind conditions and with two control strategies—droop control and inertial control to enhance its frequency support capability. The synchronous generator speed, more stable than the grid frequency which is the input signal for Type 3 and Type 4 wind turbine frequency support controller, is used for the calculation of WT-EMC supplementary torque command. The integrated simulation environment based on the aeroelastic code HAWC2 and software Matlab/Simulink is used to build a 2 MW WT-EMC model and study the frequency support capability of a wind farm consisting of WT-EMC.     

Time stepping finite element analysis of a variable speed synchronous generator with rectifier

Several applications for renewable energy conversion make use of variable speed generators. A conversion from variable frequency to grid frequency is therefore essential. One part of the converter is a rectifier. A rectifier model is presented, which is integrated in a time stepping finite element simulation environment where the generator and circuit equations are solved simultaneously. The model handles bidirectional alternator speeds as the application is a linear generator for ocean wave energy conversion. The rectifier model is extended with a load model, consisting of R, L and E, and simulations show what impact the rectifier has on the generator’s behaviour.     

一种新的变步长LMS自适应算法及其在自适应噪声对消中的应用

许多时变步长(VSS)自适应算法已经提出用来完善标准LMS算法的性能,但实验表明这些算法容易受噪声干扰.本文介绍了一种新的变步长LMS自适应算法,这种算法保证了较小的失调,同时使算法在自适应初始阶段有较快的收敛速度.该算法的优越性在于它不受已经存在的不相关噪声的干扰.本文对该算法的收敛性和稳定性进行了分析,并将该算法应用于自适应噪声对消的仿真实验中,给出了计算机的仿真结果.     

基于遗传算法的TBDD排序方法

带时间参数的二叉判决图（ＴＢＤＤ）在电路的时滞故障测试中有着重要的应用价值，但其变量排序是用常规方法无法解决的一个优化问题。本文提出一种基于遗传算法的ＴＢＤＤ排序算法。用快速衡量值和ＴＢＤＤ节点数来计算个体的适应度。针对变量排序的特定问题，提出一种模板保序交叉方法。采用知适应的变异概率计算方法，并提出一个适合于ＴＢＤＤ排序问题的变异算法。实验结果表明较好地解决了ＴＢＤＤ的排序问题。     

可变带宽的基带信号发生器设计

基于8751系列单片机的可变带宽基带信号发生器由控制电路、时钟发生、波形存储、数据输出和放大滤波等单元组成.通过单片机控制时钟发生、波形存储、数据输出和放大滤波等数字电路,可产生不同频带宽度的基带正弦扫频信号或不同脉冲宽度的脉冲调制正弦信号.     

九洲高压变频器在苏丹吉里电站锅炉给水中的应用

本文介绍了国产高压变频器在苏丹吉里火电厂锅炉给水泵中的应用,并详细描述了变频调速下的节能情况,以及在特殊环境中遇到的问题及解决方案。     

Iterative design of variable fractional-order IIR differintegrators

In this paper, the variable fractional-order (VFO) differintegrator is designed based on IIR-typed Farrow structure. The stability of the designed VFO IIR differintegrator is achieved by incorporating a constrained function into the objective error function. But the minimization of the original objective error function is a highly nonlinear problem, so an iterative quadratic method is proposed to overcome it. Comparing with the design based on FIR-typed Farrow structure, several designed examples, including a VFO differintegrator, a pure VFO differentiator and a pure VFO integrator, are presented to demonstrate the effectiveness of the proposed method.     

Variable step length finite difference method for calculation of the 3-phase electromagnetic field in the long conductor approach

The original motivation of this research is to describe comprehensive solutions based on Finite Difference Method (FDM) together with its software implementation that can handle the infinity long conductor. This paper focuses on developing FDM procedures for solving the interface regions, defined as regions where the step sizes change. Attention has been paid in this problem for creating robust and efficient techniques for solving the complex electromagnetic field at long distance from the transmission line based on a variable step size for the grid of FDM. Reduction in memory requirements has been achieved in these approaches. The industry has identified that there is a pressing need for a comprehensive method together with its software implementation that can handle the infinity long conductor problem. The research results of the project have immediate and practical application to the power industries.     

自动清洗的变速控制方法

全自动划片机是融合精密机械、电子、软件、材料、自控、光电、元器件等多学科技术为一体的IC装备。高速清洗系统作为全自动划片产品的重要组成部分,直接影响着设备整体工作的质量和效率。本文对清洗系统的变速控制和精确回零技术做了初步的探讨。伺服系统采用内部速度模式的变速控制方法,解决了大转动惯量下位置控制无法稳定的问题。清洗完成后,系统寻址高精度传感器,完成清洗台上下料的回零定位。     

基于机器视觉的条码信息在线检测系统研究

随着数字媒体技术的发展以及个性化印刷需求的增加,在印刷过程中,对可变信息进行实时监控是满足可变信息印刷需求的必要条件.本研究采用基于机器视觉的条码信息在线检测系统,利用CCD采集条码数字图像,采用图像定位、滤波去噪、二值化、定位分割等图像处理技术进行条码处理后,用相似边距离测量法进行条码识读,实现了在线检测系统对可变信息条码的快速、精确识读与检测.