Bifurcation analysis for an SMIB power system with series capacitor compensation associated with sub-synchronous resonance

In this paper,an introduction to the bifurcation theory and its applicability to the study of sub-synchronous resonance (SSR) phenomenon in power system are presented. The continuation and bifurcation analysis software AUTO97 is adopted to investigate SSR for a single-machine-infinite-bus power system with series capacitor compensation. The investigation results show that SSR is the result of unstable limit cycle after bifurcation. When the system exhibits SSR, some complex periodical orbit bifurcations, such as torus bifurcation and periodical fold bifurcation, may happen with the variation of limit cycle. Furthermore, the initial operation condition may greatly influence the ultimate state of the system. The time-domain simulation is carried out to verify the effectiveness of the results obtained from the bifurcation analysis.     

基于UC3842的反激变换器与斜波补偿

UC3842是高性能电流控制型脉宽调制（PWM）芯片,以其为核心的开关电源电路成本低廉,结构简单.但反激变换器在电流连续模式（CCM）下运行,占空比大于50%时,系统会在有扰动时发散或双闭环调节时产生分谐波振荡,使这类电源产品存在安全隐患.分析了系统控制不稳的原因,研制出能使扰动得以收敛的斜率补偿电路,电源能在小于0.1%的电压调整率,低于3%的负荷调整率的状态下,稳定运行.     

供配电系统无功补偿方案的选择

介绍无功补偿的作用、方法及原则,分析炼钢供配电系统负荷性质及无功补偿的必要性,并提出各供配电系统的无功补偿方案。     

基于嵌入式的空间光通信系统前馈补偿系统设计

为满足光通信系统对于目标数据的快速捕获需求,缩小各级通信设备间的动态跟踪误差,设计基于嵌入式技术的空间光通信系统的前馈补偿系统;以并串转换电路作为唯一的电能输出装置,在光通信信号发射模块、波分复用器件、嵌入式光放大器三个通信设备元件的共同调节作用下,确定PWM功率放大器的实时执行能力,达到对前馈型角编码器的调度与应用,实现空间光通信系统前馈补偿结构的搭建;配置Linux嵌入内核的移植协议,多次创建空间光环境下的通信数据根文件,以此为存储标准,计算补偿调制的基础传信率,实现对前馈脉冲波的调制与处理,完成嵌入式通信系统的前馈补偿原理研究;实验结果表明,应用前馈补偿系统后,在光通信参量等于5.0×1011 T、7.0×1011 T、9.0×1011 T的情况下,目标数据的捕获速率均超过7.0 T/mm,满足缩小通信设备间动态跟踪误差的实际应用需求。     

长江生态航道技术研究进展与展望

建设生态文明是中华民族永续发展的千年大计,流域经济发展要将生态保护摆在压倒性位置。系统分析了生态航道的发展历程和研究现状,重点阐述了长江生态航道技术在理论框架与评价体系、生态航道建设技术、生态监测与修复补偿方法3方面取得的重要进展和突破,并对长江生态航道技术在几个大型航道整治工程中的应用实践进行了概述,最后结合长江生态航道技术研究进展与实践,指出了未来长江生态航道技术的发展方向。     

飞翼无人机非线性控制设计方法

为实现飞翼无人机的机动飞行,以带有流体矢量方向舵的飞翼无人机为设计对象,采用非线性设计方法设计了控制器,并进行飞行验证.针对飞翼无人机的机动飞行控制存在各种耦合和扰动的特点,设计内环线性化解耦以消除已知不利的耦合项,外环反步跟踪方法进行航迹跟踪的控制律结构,证明了该控制结构的稳定性.同传统反步控制方法相比,该控制器增加了内环解耦结构,并在控制结构中保留气动阻尼项,使得线性化后的系统为弱非线性系统.该结构不仅可以降低外环控制器设计的保守性,而且便于工程实现.仿真和飞行试验表明,该控制方案是有效的.     

Robust registration based compensation method based on sparse recovery

The loss of the degree of system freedom and mismatch of prior information based on the registration based compensation (RBC) method will result in a decline in computational performance. In order to solve above problems, a robust method named SRBC is proposed where the sparse recovery method is applied instead of the sub-aperture smoothing operation. First, the SRBC utilizes the sparse recovery to get the super resolution clutter space-time spectrum. Then the transition covariance matrix is calculated. Finally, the clutter covariance matrix is reconstructed by the Capon spectrum. Compared with the traditional RBC method, the SRBC proposed does not depend on sub-aperture smoothing operation and prior information and maintains the performance of clutter range-dependence. In addition, it is also steadier when the sensor error exists. Experimental simulation demonstrates the correctness and feasibility of this method.     

BP网络算法在平面运动测量误差补偿中的应用

在航天对接试验平台开发项目中,针对平面运动物体非接触高精度测量的难点,提出一种针对物体三自由度平面运动的创新性测量方法.利用激光测距传感器的并联组合,实现对物体位置和姿态的非接触式测量.以传感器测量值为输入样本,运用BP神经网络算法建立误差模型,通过调整权值因子使建立的网络模型能够拟合出测量误差,从而修正测量的数学模型.基于BP神经网络的误差补偿方法对平面运动物体测量误差的补偿具有明显的效果,能够满足位姿测量的精度要求.     

Registration based compensation method based on adaptive subspace tracking

The registration based compensation (RBC) method is an effective method to compensate the range-dependence of the main-lobe clutter and side-lobe clutter in the same time. However, the compensation performance of the RBC degrades because of the mismatch of prior information and the loss of degree of system freedom. Moreover, the RBC is not very suited for real-time implementation because of the enormous computational complexity and memory usage of eigenvalue decomposition. In this paper, a novel clutter range-dependence compensation method using the modified maximum likelihood adaptive subspace estimation algorithm, which is named the MRBC method for short, is proposed. The eigenvectors matrix and eigenvalues matrix of the clutter covariance matrix are estimated by iterative tracking instead of temporal and spatial smoothing, spectrum calculation and eigenvalue decomposition. Compared with the traditional RBC method, the proposed method can reduce the computational complexity significantly and maintain the performance of clutter range-dependence compensation. In addition, the proposed method can also achieve good performance when the system error exists because of no use of prior information. Experimental simulations demonstrate the validity of this method.     

A new design of foaming agent mixing device for a pneumatic foaming system used for mine dust suppression

To overcome the drawbacks of the conventional foam technology used for dust suppression,including large pressure loss,high water pressure and low driving pressure,a new pneumatic foaming system is introduced.Then an original design of foaming agent mixing device is proposed,and its performance is investigated and evaluated under different pressure compensations.Experimental results show that the maximum absorption amount increases by 2.9-6.7 times at a pressure compensation of 0.04-0.2 MPa compared with no pressure compensation.The pressure loss and pressure fluctuation both reduce significantly with increasing pressure compensation.The critical outlet pressure increases by30.4-240%.Field application indicates that the proposed mixing device ensures the reliable addition of foaming agent used for foam dust suppression.The effect of foam on dust suppression is remarkable,and the economic cost of foam is low.Therefore,there is reason to believe that the new mixing device will greatly promote foam technology to be widely used for suppressing dust in underground coal mines.