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A Three-Terminal Hybrid HVDC System Based on LCC and Hybrid MMC with DC Fault Clearance Capability
Wei Han,Ruizhang Yang,Wang Xiang,Chao Liu,Weidong Ma,Jinyu Wen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
In this paper, a three-terminal hybrid HVDC system based on LCC and hybrid MMC is proposed, which has the ability of DC fault clearance. The system combines the merits of hybrid HVDC system and multi-terminal HVDC system, which is able to deliver bulk renewable power to multiple receiving power grids at a relatively lower cost. By utilizing hybrid MMC as the inverters, the system has the capability to ride through DC faults. The topology and the operating characteristics of the system are introduced in detail. The design of the hybrid MMC is analyzed. The control strategy and the DC fault ride through strategy are proposed. Finally, the model of three-terminal HVDC system is built in PSCAD / EMTDC. The simulation verifies the effectiveness of the control strategy and the DC fault ride through strategy. The results indicate that this kind of HVDC system has a good application prospect in bulk power transmission to the multiple remote receiving regional power grids and the DC fault ride through ability proposed for the system operates well.
Active current-limiting control to handle DC line fault of overhead DC grid
MENG Zhou,WANG Xiang,WENPING Zuo,WEIXING Lin,JINYU Wen,RUIZHANG Yang,BINYE Ni,XIAOJUN Lu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
To handle with the DC line faults in a DC grid, this paper proposed an active current-limiting controller for hybrid MMC. With this active current-limiting control strategy, the requirement of interruption current of DCCB will be significantly decreased, and the investment of DC grid will be reduced obviously. Firstly, the control architecture of active current-limiting controller is disclosed. To avoid the overvoltage of submodule capacitors during DC fault, a dynamic limiter for the reference value of the DC current controller is proposed. To decrease the peak of fault current, the feedforward controller of DC voltage is put forward. The decoupling controllability of the AC/DC voltage of hybrid MMC is disclosed. The currentlimiting mechanism of the active current-limiting controller is analysis. Then, the validity of the active current-limiting control strategy is verified by RTDS.
Effect of capacitor position on radiation patterns of ground radiation antenna
Rui Zhang,Yang Liu,Hyeongdong Kim IET 2015 Electronics letters Vol.51 No.23
<P>The radiation-pattern variations of a ground radiation antenna are investigated. The series capacitor connected in the antenna radiation loop is successively placed in two different positions while the radiation patterns are respectively observed. The simulation and experimental results indicate that the radiation patterns are significantly changed in accordance with the capacitor's position. This study can be applied to implementing a radiation-pattern-reconfigurable GPS antenna.</P>
PIFA using series-resonant feed structure for wide-band operations
Rui Zhang,Yang Liu,Hyeonghun Kim,Hyeongdong Kim IET 2015 Electronics letters Vol.51 No.8
<P>A newly designed two-dimensional planar inverted-F antenna (PIFA) that achieves a substantially enhanced dual-band impedance bandwidth is presented. It employs a proposed series-resonant feed structure, which consists of two series resonators. The enhanced dual-band impedance bandwidth is realised based on the appropriate increase of the impedance levels of the two series resonators. This increase is sufficient to cover wide use in mobile handsets of 698-960 MHz for the low band and 1710-2690 MHz for the high band with a VSWR <; 3.</P>
Rui Zhang,Chengyu Yang,Hetao Hou,Karlel Cornejo,Cheng Chen 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.2
Hybrid simulation (HS) has attracted community attention in recent years as an efficient and effective experimental technique for structural performance evaluation in size-limited laboratories. Traditional hybrid simulations usually take deterministic properties for their numerical substructures therefore could not account for inherent uncertainties within the engineering structures to provide probabilistic performance assessment. Reliable structural performance evaluation, therefore, calls for stochastic hybrid simulation (SHS) to explicitly account for substructure uncertainties. The experimental design of SHS is explored in this study to account for uncertainties within analytical substructures. Both computational simulation and laboratory experiments are conducted to evaluate the pseudo-random Sobol sequence for the experimental design of SHS. Metamodeling through polynomial chaos expansion (PCE) is established from a computational simulation of a nonlinear singledegree-of-freedom (SDOF) structure to evaluate the influence of nonlinear behavior and ground motions uncertainties. A series of hybrid simulations are further conducted in the laboratory to validate the findings from computational analysis. It is shown that the Sobol sequence provides a good starting point for the experimental design of stochastic hybrid simulation. However, nonlinear structural behavior involving stiffness and strength degradation could significantly increase the number of hybrid simulations to acquire accurate statistical estimation for the structural response of interests. Compared with the statistical moments calculated directly from hybrid simulations in the laboratory, the meta-model through PCE gives more accurate estimation, therefore, providing a more effective way for uncertainty quantification.
Cytoprotective Activity of Carpinus tschonoskii againstH2O2 Induced Oxidative Stress
Rui Zhang,Kyoung Ah Kang,Mei Jing Piao,Jae Woo Park,Taekyun Shin,Byoung-Sam Yoo,Young Taek Yang,Jin Won Hyun 한국생약학회 2007 Natural Product Sciences Vol.13 No.2
have studied the cytoprotective effect on H2O2 induced oxidative stress from leaves of Carpinustschonoskii. The methanol extract of Carpinus tschonoski was found to scavenge intracellular reactive oxygenspecies (ROS) using flow cytometry and confocal microscope. This extract prevented lipid peroxidation and thusreduced cell death of Chinese hamster lung fibroblast (V79-4) induced by H2O2 treatment. The extract increasedcatalase activity and phosphorylation of extracellular signal regulated kinase (ERK). Taken together, the resultssuggest that Carpinus tschonoskii protects V79-4 cells against oxidative damage by H2O2 through scavengingROS.Keywordsoxidative stress, reactive oxygen species, Chinese hamster lung fibroblast, Carpinus tschonoskii