基于MATLAB的电力系统暂态稳定性仿真研究

介绍了电力系统的暂态稳定、MATLAB环境下Simulink动态仿真工具、电力系统工具箱的功能和特点及仿真数学模型。运用MATLAB电力系统仿真模块集SimPowerSystems构建了三机系统的Simulink模型,通过对电力系统故障仿真分析,表明了该模型能较准确直观地考察暂态过程中电力系统的动态特性,说明了Matlab在电力系统仿真中的强大功能。

故障位置对交直流外送系统暂态功角稳定性的影响分析

分析电源中心交直流外送系统中故障位置对暂态功角稳定性的影响。以三机系统为例建立数学模型,其中2台等值机位于电源中心内部。简化模型后,给出2台相互耦合的等值机转子运动方程。根据转子运动方程中各项的物理意义,分情况讨论了不同位置发生故障后系统的暂态功角稳定性,并结合实际系统运行特点进行概括,得到结论如下:当电源中心内部交流联络线潮流较轻时,电源中心的交流外送通道发生故障,系统更易发生功角失稳;反之,电源中心内部发生故障,系统更易发生功角失稳,并对内部故障位置进行区分。最后,通过基于陕西电网陕北交直流外送系统的算例验证了结论的正确性。

Measuring In-Plane Micro-Motion of Micro-Structure Using Optical Flow

Optical flow method is one of the most important methods of analyzing motion images. Optical flow field is used to analyze characteristics of motion objects. According to motion features of micro-electronic mechani-cal system (MEMS) micro-structure, the optical algorithm based on label field and neighborhood optimization is presented to analyze the in-plane micro-motion of micro-structure. Firstly, high speed motion states for each fre-quency segment of micro-structure in cyclic motion are frozen based on stroboscopic principle. Thus a series of dynamic images of micro-structure are obtained. Secondly, the presented optical algorithm is used to analyze the image sequences, and can obtain reliable and precise optical field and reduce computing time. As micro-resonator of testing object, the phase-amplitude curve of micro-structure is derived. Experimental results indicate that the meas-urement precision of the presented algorithm is high, and measurement repeatability reaches 40 nm under the same experiment condition.

Large power analysis of switched reluctance machine system for coal mine

The conventional structures in the Switched Reluctance machines are introduced, such as three-phase 12/8 structure Switched Reluctance machine, three-phase 6/4 structure Switched Reluctance machine, four-phase 16/12 structure Switched Reluctance machine, and four-phase 8/6 structure Switched Reluctance machine. Three-phase 12/8 structure Switched Reluctance machine is the best choice for the large power Switched Reluctance machine system in coal mines. The asymmetric bridge power converter main circuit and the bifilar winding power converter main circuit are also introduced. Three-phase asymmetric bridge power converter main circuit is the best choice for the large power Switched Reluctance machine system in coal mines. The magnetic paths of the designed large power motor are given with one phase excitation and double phases excitation. The phase current waveforms are also given.

Adsorption mechanism of mixed salicylhydroxamic acid and tributyl phosphate collectors in fine cassiterite electro-flotation system

Two reagents including salicylhydroxamic acid(SHA) and tributyl phosphate(TBP) were tested as collectors either separately or together for electro-flotation of fine cassiterite(<10 μm).Subsequently,the flotation mechanism of the fine cassiterite was investigated by adsorbance determination,electrophoretic mobility measurements and Fourier transform infra-red(FT-IR) spectrum checking.Results of the flotation experiments show that with SHA as a collector,the collecting performance is remarkably impacted by the pulp pH value as the floatability of cassiterite varies sharply when the pH changes,and flotation with SHA gives distinct maximum at about pH 6.5.Additionally,the floatability of cassiterite is determined by using SHA and TBP as collectors.The range of pulp pH for good floatability is broadened in the presence of TBP as auxiliary collector,and the utilization of TBP improves the recovery of cassiterite modestly.Moreover,the optimum pH value for cassiterite flotation is associated with adsorbance.The results of FT-IR spectrum and the electrophoretic mobility measurements indicate that the adsorption interaction between the collectors and the cassiterite is dominantly a kind of chemical bonding in the form of one or two cycle chelate rings due to the coordination of carbonyl group,hydroxamate and P=O group to the metal tin atoms,where the oxygen atoms contained in carbonyl group,hydroxamate and P=O group of the polar groups have the stereo conditions to form five-membered rings.In addition,the adsorption interactions of SHA and TBP on the surfaces of cassiterite are also dominated by means of hydrogen bonds.

GPS and Google Earth based 3D assisted driving system for trucks in surface mines

In order to reduce the number of surface mining accidents related to low visibility conditions and blind spots of trucks and to provide 3D information for truck drivers and real time monitored truck information for the remote dispatcher, a 3D assisted driving system (3D-ADS) based on the GPS, mesh-wireless networks and the Google-Earth engine as the graphic interface and mine-mapping server, was developed at Virginia Tech. The research results indicate that this 3D-ADS system has the potential to increase reliability and reduce uncertainty in open pit mining operations by customizing the local 3D digital mining map, con-structing 3D truck models, tracking vehicles in real time using a 3D interface and indicating available escape routes for driver safety.

Human Motion Recognition Using Ultra-Wideband Radar and Cameras on Mobile Robot

Cameras can reliably detect human motions in a normal environment, but they are usually affected by sudden illumination changes and complex conditions, which are the major obstacles to the reliability and robustness of the system. To solve this problem, a novel integration method was proposed to combine hi-static ultra-wideband radar and cameras. In this recognition system, two cameras are used to localize the object＇s region, regions while a radar is used to obtain its 3D motion models on a mobile robot. The recognition results can be matched in the 3D motion library in order to recognize its motions. To confirm the effectiveness of the proposed method, the experimental results of recognition using vision sensors and those of recognition using the integration method were compared in different environments. Higher correct-recognition rate is achieved in the experiment.

Interactions Among Peakons, Dromions, and Compactons for a （2＋1）-Dimensional Soliton System

Starting from the known variable separation excitations of a(2 + 1)-dimensional generalized Ablowitz-Kaup-Newell-Segur system,rich coherent structures can be derived.The interactions among different types of solitary waves like peakons,dromions,and compactons are investigated and some novel features or interesting behaviors are revealed.The results show that the interactions for peakon-dromion,compacton-dromion,and peakon-compacton may be completely nonelastic or completely elastic.

Development of the Mechanical System on a Third-Generation Industrial Computed Tomography Scanner in Brazil

The development of measurement geometry for medical X-ray computed tomography （CT） scanners was carried out from the first to the fourth-generation. This concept has also been applied for imaging of industrial processes such as pipe flows or for improving design, operation, optimization and troubleshooting. Nowadays, gamma CT permits to visualize failure equipment points in three-dimensional analysis and in sections of chemical and petrochemical industries. The aim of this work is the development of the mechanical system on a third-generation industrial CT scanner to analyze laboratorial process columns which perform highly efficient separation, turning the ^6oCo, ^75Se, ^137Cs and/or ^192Ir sealed gamma-ray source（s） and the NaI（Tl） multidetector array. It also has a translation movement along the column axis to obtain as many slices of the process flow as needed. The mechanical assembly for this third-generation industrial CT scanner is comprised by strength and rigidity structural frame in stainless and carbon steels, rotating table, source shield and collimator with pneumatic exposure system, spur gear system, translator, rotary stage, drives and stepper motors. The use of suitable spur gears has given a good repeatability and high accuracy in the degree of veracity. The data acquisition boards, mechanical control interfaces, software for movement control and image reconstruction were specially development. A multiphase phantom capable to be setting with solid, liquid and gas was testing. The scanner was setting for 90 views and 19 projections for each detector totalizing 11,970 projections. Experiments to determine the linear attenuation coefficients of the phantom were carried out which applied the Lambert-Beer principle. Results showed that it was possible to distinguish between the phases even the polymethylmethacrylate and the water have very similar density and linear attenuation coefficients. It was established that the newly developed third-generation fan-beam arrangement gamma scanner unit has a good spatial resolution acceptable given the size of the used phantom in this study. The tomografic reconstruction algorithm in used 60 ~ 60 pixels images was the Alternative Minimization （AM） technique and was implemented in MATLAB and VB platforms. The mechanical system presented a good performance in terms of strength, rigidity, accuracy and repeatability with great potential to be used for education or program which dedicated to training chemical and petrochemical industry professionals and for industrial process optimization in Brazil.

Monte-Carlo Simulation of Multiple-Molecular-Motor Transport

Multimotor transport is studied by Monte-Carlo simulation with consideration of motor detachment fromthe filament.Our work shows, in the case of low load, the velocity of multi-motor system can decrease or increase withincreasing motor numbers depending on the single motor force-velocity curve.The stall force and run-length reducedgreatly compared to other models.Especially in the case of low ATP concentrations, the stall force of multi motortransport even smaller than the single motor's stall force.

数字式励磁调节器的运行方式综述

以4种典型的数字式励磁系统为例,较为详尽地阐明了为适应现代发电机及电力系统安全、可靠运行的需要,当数字式励磁调节器为双重化系统和三机系统时各种不同的装置运行方式的基本方法和基本原理。

Application of Novel Rotation Angular Model for 3D Mouse System Based on MEMS Accelerometers

A new scheme is proposed to model 3D angular motion of a revolving regular object with miniature, low-cost micro electro mechanical systems(MEMS) accelerometers(instead of gyroscope),which is employed in 3D mouse system.To sense 3D angular motion,the static property of MEMS accelerometer,sensitive to gravity acceleration,is exploited.With the three outputs of configured accelerometers,the proposed model is implemented to get the rotary motion of the rigid object.In order to validate the effectiveness of the proposed model,an input device is developed with the configuration of the scheme.Experimental results show that a simulated 3D cube can accurately track the rotation of the input device.The result indicates the feasibility and effectiveness of the proposed model in the 3D mouse system.