Optimization of Voltage Dip Suppression Effect by Resistor Insertion in Startup of Low-frequency Induction Furnace

2014 ◽  
Vol 134 (10) ◽  
pp. 866-874
Author(s):  
Yoshiaki Yoshida
Keyword(s):  
Induction Furnace ◽  
Low Frequency ◽  
Suppression Effect ◽  
Voltage Dip

scholarly journals On the Desulphurization of Crude Fe-Ni in the 8t Low Frequency Induction Furnace

1967 ◽  
Vol 53 (7) ◽  
pp. 810-812
Author(s):  
Hiroshi YASUDA ◽  
Takao YAMAMOTO ◽  
Ryoichi OKADA ◽  
Yutaka KABUTOYA
Keyword(s):  
Induction Furnace ◽  
Low Frequency

Influence of Series Compensation Degrees on Secondary Arc Current Characteristics under the Different Series Compensation Mode

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Yadi XIE ◽  
Baina HE ◽  
Lemiao WANG ◽  
Renzhuo JIANG ◽  
Yazhe MAO ◽  
...  
Keyword(s):  
Transmission Lines ◽  
Circuit Breaker ◽  
Low Frequency ◽  
High Amplitude ◽  
Long Distance ◽  
Series Compensation ◽  
Large Capacity ◽  
Suppression Effect ◽  
Arc Current ◽  
Compensation Device

AbstractThe high compensation degree series compensation has a broad development prospects in long distance and large-capacity UHV transmission lines. But it is generating secondary arc current contains low frequency components with high amplitude when the single-phase grounding fault occurs in the series compensated transmission line, which is not conducive to rapid arc extinguishing. To solve this problem, this paper based on the mechanism of generating secondary arc by series compensation transmission lines, and using ATP – EMTP electromagnetic transient program to establish the simulation model of UHV series compensation device. And the suppression effects of small resistance short connection fault series compensation and linkage bypass series compensation measures on secondary arc current and recovery voltage under different series compensation layout mode are studied respectively. The results show that the attenuation speed of the secondary arc current is related to the series compensation arrangement modes and the time when the series compensation device is short connected or bypassed. Series compensation device short connected or bypassed before circuit breaker tripping which can accelerate the arc extinction speed, and the suppression effect is better when the series compensated double platform segmentation layout is distributed on both sides of the line. The results can be used as a reference for the engineering design of UHV with large capacity and long distance and high compensation series compensation transmission lines.

Additional Damping Control of a Hybrid Multi-infeed DC System with a Wind Farm

2020 ◽  
Vol 13 ◽  
Author(s):  
Congshan Li ◽  
Yan Fang ◽  
Ping He ◽  
Yikai Li ◽  
Tingyu Sheng
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Wind Farm ◽  
Simulation Analysis ◽  
Oscillation Mode ◽  
Low Frequency ◽  
Simulation Software ◽  
Suppression Effect ◽  
Damping Controllers ◽  
Damping Controller

Background: In a hybrid multi-infeed direct current (HMIDC) system, the interaction between the AC and DC systems will have an influence on the damping characteristics of the system, while a doubly-fed induction generator (DFIG) -based wind turbine connected to the grid complicates the coupling between AC and DC. Objective: Based on the basic principles of wind power generation and low-frequency oscillation (LFO), a DFIG -based wind turbine is respectively connected to the LCC-HVDC side and VSC-HVSC side of an HMIDC system to study the influence of the oscillation mode on a hybrid system with different wind power access locations, and two kinds of additional DC damping controllers are designed to suppress the LFO. Comparing the effects of different additional DC damping controllers on the suppression of the LFO in the system. Methods: First, the total least squares- estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) is used to obtain the system’s oscillation mode. Second, the transfer function is determined by the Butterworth bandpass filter. Third, the LCC-HVDC and VSC-HVDC additional damping controllers are designed based on the H2/H∞ hybrid control theory. Results: The designed additional DC damping controller has a good suppression effect on LFO in the HMIDC system and can meet the system damping deficit. The effect of the LCC-HVDC additional damping controller is better than that of VSC-HVDC. Conclusion: Through a simulation analysis on PSCAD/EMTDC simulation software, the effectiveness of the designed additional DC damping controller is verified.

Adaptive robust sliding mode simultaneous control of spacecraft attitude and micro-vibration based on magnetically suspended control and sensitive gyro

2020 ◽  
Vol 234 (15) ◽  
pp. 2197-2210
Author(s):  
Yuan Ren ◽  
Xiaocen Chen ◽  
Yuanwen Cai ◽  
Weijie Wang ◽  
Qiang Liu
Keyword(s):  
Physical Simulation ◽  
Vibration Suppression ◽  
Sliding Mode ◽  
Frequency Control ◽  
Low Frequency ◽  
Magnetic Suspension ◽  
Spacecraft Attitude ◽  
Suppression Effect ◽  
Simultaneous Control ◽  
Micro Vibration

This paper puts forward realizing the synchronous control of spacecraft attitude and micro-vibration by taking advantage of magnetic suspension rotor deflection of magnetically suspended control and sensitive gyro. A disturbance-observer is designed to estimate the complex micro vibration which is hard to measure, and an adaptive robust sliding mode controller is designed as an integrated controller and its stability is proven by Lyapunov stability criterion. The band-pass filters are introduced to separate low frequency and high frequency control signals and takes them as input commands of gyro frame and magnetic suspension rotor, respectively. The semi-physical simulation results testify that the proposed method has good vibration suppression effect as well as improves the attitude convergence rate.

scholarly journals The Influence of Carbon Dioxide on Brain Activity and Metabolism in Conscious Humans

2010 ◽  
Vol 31 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Feng Xu ◽  
Jinsoo Uh ◽  
Matthew R Brier ◽  
John Hart ◽  
Uma S Yezhuvath ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Neural Activity ◽  
Resting State ◽  
Brain Activity ◽  
Low Frequency ◽  
Relative Increase ◽  
Cerebrovascular Reserve ◽  
Suppression Effect ◽  
End Tidal ◽  
Scalp Electroencephalogram

A better understanding of carbon dioxide (CO2) effect on brain activity may have a profound impact on clinical studies using CO2 manipulation to assess cerebrovascular reserve and on the use of hypercapnia as a means to calibrate functional magnetic resonance imaging (fMRI) signal. This study investigates how an increase in blood CO2, via inhalation of 5% CO2, may alter brain activity in humans. Dynamic measurement of brain metabolism revealed that mild hypercapnia resulted in a suppression of cerebral metabolic rate of oxygen ( CMRO 2) by 13.4%±2.3% ( N=14) and, furthermore, the CMRO 2 change was proportional to the subject's end-tidal CO2 (Et-CO2) change. When using functional connectivity MRI (fcMRI) to assess the changes in resting-state neural activity, it was found that hypercapnia resulted in a reduction in all fcMRI indices assessed including cluster volume, cross-correlation coefficient, and amplitude of the fcMRI signal in the default-mode network (DMN). The extent of the reduction was more pronounced than similar indices obtained in visual-evoked fMRI, suggesting a selective suppression effect on resting-state neural activity. Scalp electroencephalogram (EEG) studies comparing hypercapnia with normocapnia conditions showed a relative increase in low frequency power in the EEG spectra, suggesting that the brain is entering a low arousal state on CO2 inhalation.

Potentials evoked by stimulation of the hippocampus: Low frequency suppression effect

1975 ◽  
Vol 15 (5) ◽  
pp. 551-559 ◽  
Author(s):  
Frances Newberry ◽  
Ronald Racine ◽  
G.K. Smith
Keyword(s):  
Low Frequency ◽  
Suppression Effect ◽  
Stimulation Of

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

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