Abstract: A general power quality measuring system based on virtual instrument (LabVIEW) has been developed. For two electric railway traction transformers of Zhengzhou-Xi’an High Speed Passenger Dedicated Line, which access to Zhengzhou, Henan Grid, some important power quality parameters have been measured and analyzed. Then, the analysis results are compared with the calculation results by Power System Harmonic Penetration Software (PSHP), which is developed by our group. It shows that real measured data of Harmonic Ratio and Three-phase Unbalanced Factor of electric railway traction substations is comparable well with the calculation results. Furthermore, Three-phase Current Unbalanced Factor accorded well with the theoretical value of the V/v-connected traction transformer, and Total Voltage Harmonic Distortion and Unbalanced Factor meet the requirements of relative national standard.
Abstract: In order to ensure the operating security of pressure containers, the P. R. China make a corresponding standard of producing, checking and accepting pressure containers, in which the weld stagger joint is an importance parameter to be measured. Because the zero scale is fixed, the existing mechanical stagger joint measuring scale has scoring error of scale, zero error, visual error and cumulative error, it is not convenient to read and easy to get wrong data, resulting in misjudgment and other defects. The existing capacitive displacement sensor based instrument with digital display for measuring welded joint angularity and stagger is the parameter detection after the weld completed, it cannot be used for detecting welded joint stagger joint before welding, so it is not convenient to adjust the weld and control the welding quality. To make up for the lack of existing measurement tools, we developed a capacitive displacement sensor based portable instrument with digital display for measuring weld stagger joint. This paper introduces its structures and principle. Through error analysis, calculation and experimental testing, the integrated error of the instrument is less than 0.03 mm, the measuring accuracy can meet the requirements prescribed by the GB150-1998 standard.
Abstract: Analyzing grey correlation grade method, a fault diagnosis method of improved grey correlation grade is presented for turbine generator unit. The method calculates weight according to test sample, and then calculates the weighted grey correlation grade. And for the characteristics of turbine generation unit, a fault diagnosis method based on improved grey correlation grade is presented. Simulation results show that the proposed method can successfully diagnose all fault of turbine generation unit, and fault isolation capability is much stronger than traditional grey relation.
Abstract: A robot with a laser range finder to its hand is presented for the inspection of manufactured parts. The transformation from the hand frame to the finder frame is transformed to an optimization problem by measuring a radii-known ball with unknown position information. Test results of real experiments on a motoman robot are reported and analyzed.
Abstract: Bearing, asynchronous deep groove ball bearings are widely used in induction motor field. Motor bearing failure probability is as high as 40% in asynchronous motor. It accounts for the largest proportion of failures in the motor. Therefore, people have been on studying motor bearing fault detection methods for further research. So far, people have studied a variety of modern detection methods.
Abstract: The Lower DOF parallel robot rely on strictly geometrical constraints of axis of pairs in and between limbs to obtain the reduced number of DOF .In practice ,these constraints will never been perfectly fulfilled due to the inevitability of errors, and hence produce series bad effects and problems. Using screw theory and set theory as mathematical tools, the DOF and constraint system of 3-CRR parallel robot, were systematically summarized and in-depth studied. Kinematics design of a limited DOF parallel robot, a 3-CRR pure translational parallel robot, is presented that takes into account the error. The errors presented in the paper consist of two kinds. The errors is defined as the position error of rotation center of the platform caused by errors in the kinematics constants, such as axis error The above research results provided an insight into the error of 3CRR parallel robot.
Abstract: The action of V/Hz limiter of generator excitation system and its influence on generator in isolated operation are analyzed with the generator in Youjiang hydro power station as an example which is in isolated operation with local load after the trip of main transformer of 500kV Baise substation in Guangxi power grid. It is pointed out that the action of V/Hz limiter is the reason that causes the long time operation of generator under low voltage and low frequency status. Suggestions on the functions of V/Hz limiter and how to avoid such low voltage and low frequency operation status are proposed.
Abstract: Wind-induced vibration of long span bridges mainly as flutter, buffeting and vortex induced vibration. Buffeting and vortex-induced vibration will not cause the devastating destruction of the bridge, while the chatter is the elastic system in the air of self-excited vibration, when the vibration system from the air flow in the absorption of energy and the energy is greater than the energy damping When consumed, they cause divergence of the self-excited aerodynamic flutter vibration. If the critical flutter wind speed is less than in the bridge office potential wind speed, the bridge flutter may occur caused devastating damage. According to modern control theory, a theoretical analysis is conducted on the active control of cable-stayed bridge flutter, it is established that the controlled equation of cable-stayed bridge controlled by a single active mass damper and the motion equation of a single AMD to determine the calculation method of the critical flutter velocity under the controlled status of the cable-stayed bridge. An example shows that a single ADM is a good means to prevent the flutter damage of long-span cable-stayed bridges.
Abstract: This paper presents numerical enhancements for optimal closed-loop ascent guidance through atmospheric. For 3-dimensional ascent formulation, optimal endo-atmospheric ascent trajectory is numerically obtained by the relaxation approach, and the exo-atmospheric ascent trajectory is generated by an analytical multiple-shooting method. A new root-finding method based on double dogleg method and More’s Levenberg-Marquardt method with Gaussian elimination is presented. The simulation results indicate that our new algorithm has remarkable computation and convergence performances.
Abstract: In allusion to the compensation of environmental magnetic field for using three-axis magnetic sensor, a twelve-position calibrating method without north is designed. The equations of three-axis bias, scale factor error and install alignment error are deduced in the proposed method which is totally based on the magnetic field of up direction. According to the effect of hard iron and soft iron is equaled to the variation of three-axis bias, scale factor error and install alignment error, comparison experiments are completed in natural conditions and in conditions that the effect of hard iron and soft iron is artificially imposed. The experiment shows that this method can solve the compensation of hard iron and soft iron interference effectively for the application of up direction tumbling test.