scholarly journals RESEARCH ON SHORT-CIRCUIT IMPEDANCES OF NEW CONVERTER TRANSFORMER

2020 ◽  
Vol 38 (02) ◽  
Author(s):  
TRAN THANH NGOC
Keyword(s):  
Theoretical Analysis ◽  
Topological Structure ◽  
Short Circuit ◽  
Experimental Results ◽  
New Method ◽  
Mathematical Relationship ◽  
Hvdc System ◽  
Grid Side ◽  
Relationship Of ◽  
Circuit Impedance

The short-circuit impedance of converter transformers is one of the most important specifications in HVDC system. Compared with the traditional converter transformers, the new converter transformer has unique windings connection diagrams. Based on the topological structure of the new converter transformer, this paper proposes a new method to establish the mathematical relationship of short-circuit impedances and filters impedances under considering the valve side and grid side shortcircuit conditions. The analysis on short circuit at valve side and grid side shows that short-circuit impedances values are almost the same in both two conditions, so that the impedance of the new converter transformer is symmetrical. Finally, simulation and experimental results verify the correctness of the theoretical analysis.

Influence of Multiple Piezoelectric Effects on Piezoelectric Coefficient of Piezoelectric Ceramics

2011 ◽  
Vol 101-102 ◽  
pp. 922-925 ◽  
Author(s):  
Zhong Hua Zhang ◽  
Guang Ming Cheng ◽  
Jun Wu Kan ◽  
Ping Zeng ◽  
Jian Ming Wen
Keyword(s):  
Boundary Condition ◽  
Theoretical Analysis ◽  
Experimental Validation ◽  
Piezoelectric Coefficient ◽  
Short Circuit ◽  
Piezoelectric Ceramics ◽  
Open Circuit ◽  
Experimental Results ◽  
Experimental Result ◽  
Piezoelectric Effects

In this paper, theoretical analysis is performed on the influence of multiple piezoelectric effects on piezoelectric coefficients. And a kind of classical piezoelectric ceramics was adopted to conduct the experimental validation. The experimental results of short-circuit boundary condition are obtained by the methods that a capacitor whose capacitance is much larger than that of the stack is parallel with PZT-5. Influence results are obtained through comparing them with open-circuit piezoelectric coefficient. Experimental result shows that multiple piezoelectric effects make piezoelectric coefficient of PZT-5 be altered by 18%.

The Principle of Cepstrum and its Application in Quantitative Fault Diagnostics of Gears

1991 ◽  
Author(s):  
He Tang ◽  
Jian-Zhong Cha ◽  
Yuanhui Wang ◽  
Ce Zhang
Keyword(s):  
Theoretical Analysis ◽  
Noise Signal ◽  
Experimental Results ◽  
New Method ◽  
Fault Diagnostics ◽  
Gear Noise ◽  
Gear Mesh ◽  
Cepstrum Analysis

Abstract This paper has studied the principle of cepstrum and introduced a new method which can be used to quantitatively diagnose gear-wear through cepstrum analysis of gear noise. The amplitude value of the peak in cepstrum, which represents gear mesh-harmonics in spectrum, is independent of the intensity of gear noise signal. The value can indicate quantitatively the existence of gear-wear. In the paper, the further interpretation on physical meanings of other peaks in cepstrum has been done. Based on analysing the results of experiments with gearboxes, the thresholds of the gear wear by cepstrum diagnosis have been obtained. The theoretical analysis has agreed with the experimental results very well.

Microstructure Analysis of in-Plane Quasi-Isotropic Composites Reinforced by Multi-Direction and Multi-Layer Three Dimensional Fabric

2011 ◽  
Vol 415-417 ◽  
pp. 210-213
Author(s):  
Lan Ying Liu ◽  
Ya Nan Jiao
Keyword(s):  
Cross Section ◽  
Volume Content ◽  
Three Dimensional ◽  
Unit Cell ◽  
Experimental Results ◽  
The Other ◽  
Cell Models ◽  
Mathematical Relationship ◽  
Fiber Volume ◽  
Relationship Of

In this paper, a new multi-direction three-dimensional fabric, called in-plane quasi-isotropic fabric, including warps 0, wefts 90o, a set of bias yarns ±45o, and a vertical yarns Z fastening the other yarns together is designed. Unit cell models are established on the basis of the rule of yarn movement and on the basis of optimizing the yarn cross section on the method of braiding-solidify-cutting-polishing-viewing. Mathematical relationship of the parameters with geometry parameters is founded and the fiber volume content is calculated, the valid relationship is proved by experimental results.

NON-DIVERGING DARK-HOLLOW BEAM GENERATION WITH A PIGTAILED LASER DIODE

2008 ◽  
Vol 17 (03) ◽  
pp. 305-314
Author(s):  
M. BRUNEL ◽  
D. MGHARAZ ◽  
S. COETMELLEC ◽  
A. BOULEZHAR
Keyword(s):  
Theoretical Analysis ◽  
Laser Diode ◽  
Single Mode ◽  
Experimental Results ◽  
New Method ◽  
Circular Aperture ◽  
Hollow Beam ◽  
Beam Generation ◽  
Hollow Beams

A new method to generate non-diverging dark-hollow beams at the output of a single-mode pigtailed laser diode is presented. It consists of positioning a circular aperture at the output of the fiber. The dark-hollow beam generated exhibits an angle of divergence as low as 0.28 degrees. The beam can then be collimated by a lens to observe a non-diverging dark-hollow beam which conserves its structure over more than 20 cm. Experimental results are well-predicted by the theoretical analysis that we have developed.

A New Image Encryption Algorithm of Input-Output Feedback Based on Multi-Chaotic System

2010 ◽  
Vol 40-41 ◽  
pp. 924-929
Author(s):  
Yong Yi Mao ◽  
Zi Chao Deng
Keyword(s):  
Theoretical Analysis ◽  
Image Encryption ◽  
Chaotic System ◽  
Output Feedback ◽  
Logistic Map ◽  
Experimental Results ◽  
New Method ◽  
Encryption Algorithm ◽  
Input Output ◽  
Image Encryption Algorithm

In this paper, a new method is proposed for image encryption by using Transformed Logistic map and Cat map. First, the Transformed logistic map is used to generating two coordinate sequences, and then the primary image's pixels shuffled by the two coordinate sequences. After shuffling, the key stream is produced by the Cat map to encrypt the shuffled image. Theoretical analysis and experimental results indicate that the proposed algorithm has a perfect encryption effect and can resist common attacks

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

A new method for monitoring the redox potential of fuel salt based on the deposition of 95Nb on Hastelloy C276

2021 ◽  
Vol 109 (5) ◽  
pp. 357-365
Author(s):  
Zhiqiang Cheng ◽  
Zhongqi Zhao ◽  
Junxia Geng ◽  
Xiaohe Wang ◽  
Jifeng Hu ◽  
...  
Keyword(s):  
Redox Potential ◽  
Molten Salt ◽  
Specific Activity ◽  
Chemical Reduction ◽  
Quantitative Approach ◽  
Experimental Results ◽  
New Method ◽  
Molten Salt Reactor ◽  
Fuel Salt ◽  
Well Correlation

Abstract To develop the application of 95Nb as an indicator of redox potential for fuel salt in molten salt reactor (MSR), the specific activity of 95Nb in FLiBe salt and its deposition of 95Nb on Hastelloy C276 have been studied. Experimental results indicated that the amount of 95Nb deposited on Hastelloy C276 resulted from its chemical reduction exhibited a positive correlation with the decrease of 95Nb activity in FLiBe salt and the relative deposition coefficient of 95Nb to 103Ru appeared a well correlation with 95Nb activity in FLiBe salt. Both correlations implied that the measurement of 95Nb activity deposited on Hastelloy C276 specimen might provide a quantitative approach for monitoring the redox potential of fuel salt in MSR.

scholarly journals Coordinated Control of RSC and GSC for DFIG System under Harmonically Distorted Grid Considering Inter-Harmonics

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 28 ◽  
Author(s):  
Bo Pang ◽  
Hui Dai ◽  
Feng Li ◽  
Heng Nian
Keyword(s):  
Theoretical Analysis ◽  
Control Strategy ◽  
Coordinated Control ◽  
Delay Compensation ◽  
Pass Filter ◽  
Grid Connection ◽  
Distorted Grid ◽  
Negative Impacts ◽  
Doubly Fed ◽  
Grid Side

For improving the performance of a doubly fed induction generator (DFIG) system under a harmonically distorted grid, this paper proposes a coordinated control strategy which is effective for grid inter-harmonics as well as grid integer harmonics. In order to suppress the negative impacts caused by grid harmonics, including inter-harmonics, this paper introduces an additional harmonics suppression controller, which contains a Chebyshev high-pass filter and a modified lead element considering the delay compensation. The proposed controller is employed in the rotor side converter (RSC) and grid side converter (GSC). Based on the proposed harmonics suppression controller, a coordinated control strategy between RSC and GSC is developed, in which the control targets, including the sinusoidal output current, constant power, or steady generator torque, can be achieved for DFIG, while GSC is responsible for maintaining the sinusoidal total current to guarantee the power quality of the grid connection. The effectiveness of the proposed method is verified by the theoretical analysis, and the experimental results derived using a 1 kW DFIG system validate the correctness of the theoretical analysis.

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