A Fault Location Algorithm for Transmission Lines in Circle Network

A fault location algorithm for transmission lines in circle network is presented.The algorithm uses local data. Its location accuracy is independent of power # flow, transient resistance and variation of remote system impedance. Simulation results are satisfactory.     

A New Method of Extracting Fault Components Under Power System Swing

To solve the problem that the existing method of extracting fault components is easily affected by power system swing,a new methed has been proposed in this paper,which can be used in high speed protection of transmission lines. This proped method ean greatly decrease unbal-ance outputs under power swing condilions without frequency tracking circuits,therefore it can make the protection using fault compnents operate correctly.     

THE NEW PHASE SELECTION SCHEMES ON USE OE FAULT COMPONENT

In accordance with the characteristic of digital relay and fault locatoin four methods of phase selection on fault component are presented in this paper.These methods are simple in principle, reliable in action, and immune from load flow,system oscillation.Hardly affected by fault location, source impedance and fault resistance, they can select fault phase reliably for any power system and fault type.As phase selection schemes, they can be used for perfect digital relay.     

Detecting a fault line under a single phase to ground of distribution network based on analysis of multi frequency bands

Addressing the problem of choosing a fault line under single phase to ground of distribution network, we presented a new criterion based on analysis of the development of fault line selection and a method using wavelet packets. The feature frequency band, or the combined feature frequency bands of each line, in which the transient capacity current was concentrated was chosen for maximum energy. Based on the principle that the transient capacity current's energy of the fault line was larger than the that of normal lines, fault line selection can be carried out adaptively by contrasting the energy of the transient capacity currents of all lines in each chosen frequency band. The simulation results and spot testing data shows the proposed method can detect the fault line in distribution networks precisely and reliably.     

A numerical study of infiltration through crusted soils: Flat and other surface configurations

A finite-difference numerical solution of Richards' infiltration equation is developed for one and two-dimensional vertical flow. The model is first validated against experimental observations obtained on a vertical sand column. A comparison between two ways of modelling the crust is presented. In the first approach the crust is assumed to be instantaneously saturated and has an impedance characterized by a hydraulic resistance. The alternative method considers the crust and the underlying soil as a two-layered system. The two methods give almost the same infiltration flux with the only difference that ponding time is shorter for the impedance model since no water is needed to saturate the crust. Also the numerical model is applied to crusted furrow to compare the solution given by a two-dimensional method with one obtained by a one-dimensional approach. It is found that topographic form of the surface at this small scale is not an important parameter.     

Design of networking condition monitoring andfault diagnosis for wind turbine transmission system

In order to solve the incipient fault diagnose problem of the transmission system, a networking condition monitoring and failure diagnosis system based on B/S and C/S hybrid architecture for wind turbine transmission system is designed in the paper. Firstly, the paper analyzes the demands of condition monitoring and fault diagnosis system for wind turbine transmission system, and designs its overall framework and function modules. Then, combining with the data acquisition equipment, by the .NET and SQL Server platform, the paper designs condition monitoring and failure diagnosis system for wind turbine transmission system, which includes the functions of networking data acquisition, remote condition monitoring, signal analysis, fault diagnosis and database as well. The system has been successfully applied to a condition monitoring and fault diagnosis of wind turbine transmission system.     

Application on Extracting Feature in State Monitoring and Fault Diagnosis

With the development and application of information and internet and virtual instrument technology ,the virtual globular company based on internet arises .To study remote state monitoring, remote fault detection and diagnosis about large scale, complicated and integrative equipment become very important. In the whole fault diagnosis system , the detecting ,data acquisition is original ,processing; transform and extracting features with the signal detected is a key factor. The theories and methods used in mechanical fault diagnosis is stated. The application of signal process and its feature extracting methods is introduced which are time domain, frequency domain and time frequency domain analysis, in state monitoring and fault diagnosis with its signal analysis. The processing method of random time variant special signal is given also.     

Development of the remote data supervisory system of the hybrid electric vehicle

Taking the hybrid electric vehicle as the investigation subject, this paper studies the remote data acquisition, supervisory control and redisplay system of the hybrid electric vehicle fault diagnosis. The system gathers the simulate CAN BUS data through serial ports by the data acquisition device and send data to the remote web servers by the GPRS wireless communication module. For the demands and features, the paper makes the module selection and design the hardware of lower computer ,and the software on the host computer and lower computer. It takes several notebooks as the simulate vehicle date emission source to make an experiment, achieving the function of wireless data transfer, data acquisition, supervisory, redisplay for multi hybrid electric vehicles at the same time, and protocol setting up. Especially the function of wireless data transfer and protocol setting up, make a big progress on the common use and convenience of fault diagnosis system.     

An analysis of seed development in Pisum sativumL. XVI. Assessing variation for fatty-acid content by use of a non-destructive technique for single-seed analysis

Analyses of seeds from a wide range of pea lines have revealed extensive variation for all of the major fatty acids normally found in pisum. Unlike total lipid content, this variation was not affected by the presence of mutant alleles at the r and rb loci. To allow chemically analysed seed to be used in crosses, which is of particular importance for F₂ seed, a method has been developed by which individual seeds can be analysed non-destructively. This system entails drilling a small hole in the seed, away from the embryonic axis. The small quantity of powder produced by this process can be used for the chemical analysis but does not prevent the seed from being grown to produce progeny. Reducing the sample size had no significant effect upon the compositional analysis of the fatty acids.     

State and Prospects of Diesel Engine Fault Diagnosis Technique

As a kind of complex power machinery, diesel engine is being paid more and more attention to its condition monitoring and fault diagnosis technology. In the fault diagnosis field of diesel engine, the technique of signal process, character abstraction and identification method have formed a system, but there is a certain distance away from practical. This paper analyzes the common faults and influencing factor of diesel engine. The principle, characteristic and disadvantage of modern fault diagnosis technology, such as various time-frequency methods based on vibration signal, speed fluctuation method, iron content and spectrometry, grey system theoretical diagnosis method, artificial neural network and expert system fault diagnosis method, were reviewed. The difficulties and the development direction of diesel engine fault diagnosis were put forward in the end.     

The Fault Calculation of the Transposed and Untransposed Transmission Lines

This paper presents a method which can accurately calculate the fault voltages and currents of the transposed and untransposed transmission lines.It can be applied to the simulation of protection relay analysis and fault location and so on.The principle of method is clear,the computational precision is high and usage is simple.     

Research on differential protection for micro-grid usingfailure message with direction information

Considering traditional current protection cannot satisfy the micro-grid, a system protection solution for the micro-grid is proposed. In this solution, the failure message with direction information can be exchanged among the adjacent protection units, so the fault coverage can be determined and the fault can be quickly cleared. By analyzing the movement of the protection in three kinds of fault conditions in the micro-grid that contains three branches and two micro-power based on inverter, the method has been proved that the fault can be quickly cleared and the protection has the same protection strategies for both islanded and grid-connected operation.     

CALCULATING APPROACH FOR SOLVING LARGE-SCALE POWER SYSTE WITH TOPOLOGY AND PARAMETER GHANGES

A straightforward and unified approach for solving the large-scale, faulted power systems is presented in this paper. In contrast .with conventional algorithms, the various changes of topology and impedance of the systems and its boundary conditions of fault can be handled flexibility and effectively in one-step procedure by proposed method, and it is convenient to choose the computational procedure more resonable according to the situation of power systems. One of the noteworthy features of the proposed method is the natural manner to handle mutual effects, and it is easy to design programs. The calculating technique for easy-to-program is given in this paper. It shows that effectiveness of calculating large-scale faulte power systems with topology and impedance changes by the modified current sources.     

Design and Realization on Remote Condition Monitoring System for Feeding Oil Pump

In view of the actuality of the feeding oil pum monitoring,the network technology,the database technology and the Dot Net remote technology are integrated nimbly to construct the remote condition monitoring system for feeding oil pump,which has many functions such as the real-time data monitoring and alarm,real-time monitor data storage remote monitoring,network data sharing,fault analysis,and so on.The whole construction design of the system and the realization of its sub function are given.The worker's intensity of labor,the maintenance cost and the accident occurrence rate of the feeding oil pum were dramatically reduced when the system was applied to the oil storeroom successfully.     

Fault Detection Techniques for Feeder Automation

Fault detection of the distribution systems is one of the key techniques for feeder automation. At all times, it is still very difficult for the exact detection of single phase to ground fault. First of all, the distinguishing rules of the faulted phase are presented when ground fault occurs in distribution systems. This paper analyzes the fault detection technique for single phase to ground in system with floating neutral point. Based on faulted phase's current, a method realizing ground fault protection is proposed and the algorithm model of action criterion is given out. The simulation results show that the method will be with very good selectivity to ground fault, and it can be used preferably in feeder automation. The detection method for short circuit fault is also introduced simply.     

A STUDY ON THE IMAGE RECONSTRUCTION AIGORITHM FOR ELECTRICAL IMPEDANCE CT

A new image reconstruction method fur electrical impedance CT is derived rigorously. The Jacobi Matrix is made sparse by analysing each narrow region which is detrmined by equipotential lines seperately. Both storage and computation can be deduced. The method is realized by using first order square FEM and some computer model is reconstructed. The relaxed version of Hildreth's method for interval convex programing is applied, which can hold the sparsity of the Jacobi Matrix and overcome the ill-condition of the matrix.     

An improved dynamic model of transformer hotspot temperature based on top oil temperature

The winding hot spot temperature of the oil immersed power transformer is an important parameter. It has a great influence on the transformer insulation aging and a close relationship with the transformer top oil temperature. The changes of non linear thermal resistance, open circuit impedance, and oil viscosity and winding losses with temperature are also taken into account. An improved model added on the transformer top oil temperature to calculate transformer winding hot spot temperature by using the viscosity and loss correction factors is proposed. Model parameters are estimated by Levenberg Marquardt method. In the end, by comparing with the measured data tested under different conditions, the model shows good consistency under underload (90%), rated load (100%) and overload (110%) conditions respectively, and describes the temperature variation more accurately in the dynamic loading profiles.     

应用主动传感器GreenSeeker估测大豆籽粒产量

主动遥感技术可以方便、快捷、无损伤性地监测大豆生长。以黄淮海地区圣丰种业2011年和2012年大豆育种品系和重组自交家系(NJRIKY)共1272个家系为材料,分组设置试验,分别采用随机区组、重复内分组以及格子设计,重复3次,使用主动传感器GreenSeeker监测苗期、开花期、结荚期和鼓粒期冠层反射光谱,获得冠层归一化植被指数(NDVI),搜索大豆冠层NDVI与产量的共变化规律,建立产量估算模型。结果表明,大豆冠层NDVI随生育期的推进呈"低—高—低"变化趋势;基于单一生育期冠层NDVI建立的产量估测模型大多为简单线性回归,鼓粒期效果最好;基于多生育期冠层NDVI建立的产量估测模型中,由育种家系试验建立的大豆产量最佳估测模型(y=e6.9-4.1x1+4.3x2+1.4x3)的决定系数(R2)可达到0.66;用此模型对NJRIKY估产,与实际产量的符合度可达0.59。所建模型具有一定的预测效果,在规模化育种中可用于育种中期无重复试验的产量预测和初步选择。     

Analysis on the method of selecting nodes on the erosion diagnosisof grounding grid

The number of underdetermined equation, which is limited by the grounding down lines, reduces the grounding grid corrosion diagnostic precision. Based on the grounding grid fault diagnosis method and sensitivity analysis, the value of slip resistance change on the impact of the port resistance in several cases, such as small span, large span and edge, center and symmetrical cross line of the grounding grid, is analyzed. A new method which is used to select the node pairs to calculate the corrosion situation of grounding grid is presented. Based on this method, the simulation analysis and field test has been done. The experimental results show that this method could improve the accuracy and efficiency of grounding grid fault diagnosis.     

高梁体细胞无性系变异的筛选与利用

选用幼穗、幼胚、茎尖等五种外植体进行组培,结果表明,幼穗和幼胚的分化率最高,最适宜选用进行高粱体细胞克隆变异利用研究。对9个高粱品系的166个R2代株系进行了观察分析,除两个品系外,其余7个均有变异株系出现,其中晋粱5号的变异频率高达26%,9个品系的平均变异频率为11.24%。筛选到多个高粱骨干恢复系的无性系变异材料,并且以优良变异系R111为父本育成了优良杂交种一个,已通过审定,定名为晋杂18号。