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Series transformer based diode-bridge-type solid state fault current limiter

Amir HEIDARY,Hamid RADMANESH,Seyed Hamid FATHI,G. B. GHAREHPETIAN

《信息与电子工程前沿(英文)》 2015年 第16卷 第9期   页码 769-784 doi: 10.1631/FITEE.1400428

摘要: We propose a novel series transformer based diode-bridge-type solid state fault current limiter (SSFCL). To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch (insulated-gate bipolar transistor, IGBT) and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be controlled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor ( ) and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling (PCC) is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage (TRV) of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measurement results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.

关键词: Solid state fault current limiter (SSFCL)     Power quality     Voltage sag     Point of common coupling (PCC)     Isolation transformer    

Planning and analysis of the demonstration project of the MVDC distribution network in Zhuhai

Lu QU, Zhanqing YU, Qiang SONG, Zhichang YUAN, Biao ZHAO, Dawei YAO, Jianfu CHEN, Yao LIU, Rong ZENG

《能源前沿(英文)》 2019年 第13卷 第1期   页码 120-130 doi: 10.1007/s11708-018-0599-2

摘要: The DC distribution system is an important development direction of the distribution system, which can improve the reliability and the quality of the power supply, and support the new energy, the energy storage, the electric vehicles, and the flexible access of AC and DC loads to grid. To realize the demonstration application of the DC distribution technology, China’s first demonstration project of the medium voltage DC distribution network will be built in Zhuhai, Guangdong Province to support the construction of the city energy internet. First, this paper analyzes the demand of the DC distribution network project, and puts forward the construction content and construction target. Then, it designs and analyzes the electrical connection mode, system operation mode, and startup and shutdown mode of the DC distribution network, and proposes the overall project construction plan. Finally, it conducts the specific project design and analysis, which mainly include the selection of equipment such as inverters, DC transformers and DC circuit breakers, the design and analysis of the DC control and protection system, the design and analysis of the over-voltage protection and the configuration scheme of the lightning arrester, and analysis of the system transient characteristics. The design and analysis of the engineering program is a combination of China’s distribution network engineering practice and technical characteristics, which lays a solid foundation for the advancement of the DC power distribution technology in China, and has reference value and demonstration effect for the design and construction of other projects.

关键词: MVDC distribution network     DC solid state transformer     DC circuit breaker     modular multilevel converter    

Solid-state transformer-based new traction drive system and control

Jianghua FENG, Jing SHANG, Zhixue ZHANG, Huadong LIU, Zihao HUANG

《机械工程前沿(英文)》 2018年 第13卷 第3期   页码 411-426 doi: 10.1007/s11465-018-0467-0

摘要:

A new type of traction drive system consisting of solid-state traction transformer (SSTT), inverter unit, auxiliary inverter, traction motor and other key components is built in order to suit the demand of developing the next-generation electric traction system which will be efficient and lightweight, with high power density. For the purpose of reducing system volume and weight and improving efficiency and grid-side power quality, an efficient SSTT optimized topology combining high-voltage cascaded rectifiers with high-power high-frequency LLC resonant converter is proposed. On this basis, an integrated control strategy built upon synchronous rotating reference frame is presented to achieve unified control over fundamental active, reactive and harmonic components. The carrier-interleaving phase shift modulation strategy is proposed to improve the harmonic performance of cascaded rectifiers. In view of the secondary pulsating existing in a single-phase system, the mathematical model of secondary power transfer is built, and the mechanism of pulsating voltage resulting in beat frequency of LLC resonant converter is revealed, so as to design optimum matching of system parameters. Simulation and experimental results have verified that the traction system and control scheme mentioned in this paper are reasonable and superior and that they meet the future application requirements for rail transit.

关键词: solid-state traction transformer     high-voltage cascaded rectifier     LLC resonant converter     synchronous rotating reference frame     carrier-interleaving phase shift control     secondary pulsating voltage     beat frequency    

Biological pretreatment of corn stover by solid state fermentation of

Jian ZHANG, Xin REN, Wenqun CHEN, Jie BAO

《化学科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 146-151 doi: 10.1007/s11705-012-1220-6

摘要: Biological pretreatment is a promising way to overcome the biorecalcitrance of cleaving the supermolecular structure of lignocellulose by lignin degrading enzymes from microorganisms. Solid state fermentation of corn stover with the white-rot fungus was carried out and the efficiency of this pretreatment was evaluated. The enzymatic hydrolysis yield reached a maximum when the corn stover was biologically pretreated for nine days, and the hydrolysis yield decreased sharply if the solid state fermentation was carried out for more than nine days. A possible explanation for this sharp decrease is that not only the lignin degrading enzymes (LiP and MnP) were secreted, but also other metabolites, which were toxic or fatal to the hydrolysis enzymes resulting in the lower hydrolysis yield were generated during the prolonged period of biopretreatment. These results are useful to help determine the optimal timing and to understand the lignin structure and degradation mechanism in biological pretreatment processes.

关键词: biological pretreatment     Phanerochaete chrysosporium     solid state fermentation     biorecalcitrance     hydrolysis yield    

一种汽油变频发电机组中的辅助直流电源设计

万健如,牛亮,刘建华,牟江峰,余小红

《中国工程科学》 2007年 第9卷 第4期   页码 31-34

摘要:

针对汽油变频发电机组中逆变器所需多组低压直流电源问题,设计了一种多路输出的开关辅助电源, 结构简单紧凑、输出电压纹波小、体积小、成本低;通过分析高频变压器的设计原理,设计了一台功率为15W 的四路直流输出的开关辅助电源;实验证明了该辅助电源的可行性。

关键词: 汽油变频发电机组     直流辅助电源     三端单片开关电源     高频变压器    

Solubility of CO in solid-state PET measured by pressure-decay method

CHEN Miaocan, ZHAO Ling, LIU Tao, WU Jiangwei, YUAN Weikang

《化学科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 214-219 doi: 10.1007/s11705-008-0040-1

摘要: The solubility of CO in solid-state PET was measured using a pressure-decay method. In order to calculate the solubility of CO in the amorphous region of PET, the crystallinity of solid state PET dissolved in CO at different pressures and temperatures was measured by differential scanning calorimetry (DSC). The solubility increases with increasing pressure and it follows a linear relationship and obeys Henry’s law when the pressure is below 8 MPa. The effect of temperature on solubility is weak and the solubilities at different temperatures are almost the same under low pressures. At higher pressure, the solubility decreases with an increase in temperature. The solubility of CO in the amorphous region of PET at 373.15 K, 398.15 K and 423.15 K was correlated with the Sanchez-Lacombe equation of state with a maximal correlation error of 6.69%.

关键词: Sanchez-Lacombe equation     solid-state PET     different     relationship     calorimetry    

Highly effective extraction of oil from soybean by pretreatment of solid-state fermentation with fungi

Xiaojuan NIU, Shuyi QIU, Yuangen WU, Jie YUAN, Yingying XU

《化学科学与工程前沿(英文)》 2011年 第5卷 第1期   页码 122-125 doi: 10.1007/s11705-010-0533-6

摘要: The solid-state prefermentation by (CICC 2377) and (CICC 40536) was employed to increase the oil extraction yield from soybean. The influence of incubation time on oil yield was investigated. The maximum oil yield extracted from the substrate prefermented by for 96 h was 23%, which increased by 47.4% compared with control (15.6%). In the same fermentation conditions, the maximum oil yield extracted from substrate prefermented by was 21.6%, which increased by 38.5% compared with control (15.6%). The quality of soybean oil was not changed obviously by the pretreatment of fermentation with fungi.

关键词: soybean     Aspergillus niger     Aspergillus flavus     solid-state fermentation     extraction of oil    

Promoting hydrogen industry with high-capacity Mg-based solid-state hydrogen storage materials and systems

《能源前沿(英文)》 2023年 第17卷 第3期   页码 320-323 doi: 10.1007/s11708-023-0889-1

摘要: Promoting hydrogen industry with high-capacity Mg-based solid-state hydrogen storage materials and systems

关键词: materials systems    

Study on microbial protein and the mechanism of solid-state fermentation with periodical dynamic changes

FU Xiaoguo, CHEN Hongzhang, LI Hongqiang, MA Runyu

《化学科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 113-117 doi: 10.1007/s11705-007-0021-9

摘要: The effect of different extraction and purification conditions on the microbial protein obtained from solid-state fermentation (SSF) and the effect of periodical dynamic changes of air on protein have been studied. The mechanism of solid-state fermentation with periodical dynamic changes of air is also discussed. Compared with static solid-state fermentation, periodical dynamic changes of air afford a higher protein mass; from 1 g of the fermentation microbe, 5.3 mg of the intracellular protein (an increase of 34.63%) and 9.09 mg of the extracellular protein (an increase of 17.8%) were obtained on the sixth day of fermentation. The filter paper activity and carboxymethyl cellulose activity (FPA and CMCase) of the extracellular protein are 1.739 μmol/s and 109.592 μmol/s, respectively, which represent increases of 60.1% and 21.2% over the corresponding values for static solid-state fermentation. The FPA and CMCase of the intracellular protein are 0.245 μmol/s and 6.392 μmol/s, respectively, which represent decreases of 22.2% and 38.7% over the corresponding values for static solid-state fermentation. The enzyme activity of the microbial extracellular protein in solid-state fermentation with periodical dynamic changes of air on the fifth day is nearly equal to that on the sixth day without periodical dynamic changes of air, so the period of fermentation can be shortened. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) experiments suggest that pulsating air pressure stimulation leads to a decrease in the amount of protein component with molecule mass of about 80400Da, and an increase in the amount of protein component with molecule mass of about 28520Da.

Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

《化学科学与工程前沿(英文)》 2020年 第14卷 第2期   页码 159-187 doi: 10.1007/s11705-019-1885-1

摘要: Metal-containing zeolite catalysts have found a wide range of applications in heterogeneous catalysis. To understand the nature of metal active sites and the reaction mechanism over such catalysts is of great importance for the establishment of structure-activity relationship. The advanced solid-state NMR (SSNMR) spectroscopy is robust in the study of zeolites and zeolite-catalyzed reactions. In this review, we summarize recent developments and applications of SSNMR for exploring the structure and property of active sites in metal-containing zeolites. Moreover, detailed information on host-guest interactions in the relevant zeolite catalysis obtained by SSNMR is also discussed. Finally, we highlight the mechanistic understanding of catalytic reactions on metal-containing zeolites based on the observation of key surface species and active intermediates.

关键词: metal-containing zeolites     solid-state NMR     active site     host-guest interaction     reaction mechanism    

State-of-the-art applications of machine learning in the life cycle of solid waste management

《环境科学与工程前沿(英文)》 2023年 第17卷 第4期 doi: 10.1007/s11783-023-1644-x

摘要:

● State-of-the-art applications of machine learning (ML) in solid waste (SW) is presented.

关键词: Machine learning (ML)     Solid waste (SW)     Bibliometrics     SW management     Energy utilization     Life cycle    

A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

《能源前沿(英文)》 2023年 第17卷 第4期   页码 504-515 doi: 10.1007/s11708-022-0855-3

摘要: Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies. As a solid-solid phase change material, shape-memory alloys (SMAs) have the inherent advantages of leakage free, no encapsulation, negligible volume variation, as well as superior energy storage properties such as high thermal conductivity (compared with ice and paraffin) and volumetric energy density, making them excellent thermal energy storage materials. Considering these characteristics, the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle. The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2 °C at 9.85 s, which is reduced by 9.8 °C, and the energy storage efficiency of the device is 66%. The influence of initial temperature, elastocaloric materials, and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed. Since SMAs are both solid-state refrigerants and thermal energy storage materials, hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.

关键词: shape-memory alloy (SMA)     elastocaloric effect (eCE)     cooled seat     cold thermal energy storage    

Phase transition regulation and caloric effect

《能源前沿(英文)》 2023年 第17卷 第4期   页码 463-477 doi: 10.1007/s11708-023-0860-1

摘要: Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration. Numerous methods have been proposed to optimize the refrigeration properties of caloric materials, of which single field tuning as a relatively simple way has been systemically studied. However, single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects, like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis. Because of the shortcomings of the caloric effect driven by a single field, multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view. This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials, consisting of enlarging caloric effects, reducing hysteresis losses, adjusting transition temperatures, and widening transition temperature spans, which indicate that further progress can be made in the application of this method. Furthermore, research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms, calling for more attention on multicaloric effects. Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.

关键词: phase transition regulation     caloric effect     solid state refrigeration    

Covalent triazine framework with efficient photocatalytic activity in aqueous and solid media

Cyrine Ayed, Wei Huang, Kai A. I. Zhang

《化学科学与工程前沿(英文)》 2020年 第14卷 第3期   页码 397-404 doi: 10.1007/s11705-019-1884-2

摘要: Covalent triazine frameworks (CTFs) have been recently employed for visible light-driven photocatalysis due to their unique optical and electronic properties. However, the usually highly hydrophobic nature of CTFs, which originates from their overall aromatic backbone, leads to limitations of CTFs for applications in aqueous media. In this study, we aim to extend the range of the application media of CTFs and design hybrid material of a CTF and mesoporous silica (SBA-15) for efficient photocatalysis in aqueous medium. A thiophene-containing CTF was directly synthesized in mesopores of SBA-15. Due to the high surface area and the added hydrophilic properties by silica, the hybrid material demonstrated excellent adsorption of organic molecules in water. This leads not only to high photocatalytic performance of the hybrid material for the degradation of organic dyes in water, but also for efficient photocatalysis in solvent-free and solid state. Furthermore, the reusability, stability and easy recovery of the hybrid material offers promising metal-free heterogeneous photocatalyst for broader applications in different reaction media.

关键词: photocatalysis     covalent triazine framework     aqueous medium     SBA-15     solid state    

一种低电流纹波的低压大电流DC-DC变换器的研究

王萍,孙栩,宋良瑜

《中国工程科学》 2005年 第7卷 第4期   页码 59-63

摘要:

通过n个倍流整流结构交错并联方式用以进一步减小纹波电流。给出了电路的开关信号波形和仿真模型,并使用Pspice仿真软件对该模型进行仿真,取得满意效果。最后通过实验验证。这种结构特别适用于通信设备、计算机、宇航等领域的电源。

关键词: 低压大电流DC-DC变换器     倍流整流     交错并联    

标题 作者 时间 类型 操作

Series transformer based diode-bridge-type solid state fault current limiter

Amir HEIDARY,Hamid RADMANESH,Seyed Hamid FATHI,G. B. GHAREHPETIAN

期刊论文

Planning and analysis of the demonstration project of the MVDC distribution network in Zhuhai

Lu QU, Zhanqing YU, Qiang SONG, Zhichang YUAN, Biao ZHAO, Dawei YAO, Jianfu CHEN, Yao LIU, Rong ZENG

期刊论文

Solid-state transformer-based new traction drive system and control

Jianghua FENG, Jing SHANG, Zhixue ZHANG, Huadong LIU, Zihao HUANG

期刊论文

Biological pretreatment of corn stover by solid state fermentation of

Jian ZHANG, Xin REN, Wenqun CHEN, Jie BAO

期刊论文

一种汽油变频发电机组中的辅助直流电源设计

万健如,牛亮,刘建华,牟江峰,余小红

期刊论文

Solubility of CO in solid-state PET measured by pressure-decay method

CHEN Miaocan, ZHAO Ling, LIU Tao, WU Jiangwei, YUAN Weikang

期刊论文

Highly effective extraction of oil from soybean by pretreatment of solid-state fermentation with fungi

Xiaojuan NIU, Shuyi QIU, Yuangen WU, Jie YUAN, Yingying XU

期刊论文

Promoting hydrogen industry with high-capacity Mg-based solid-state hydrogen storage materials and systems

期刊论文

Study on microbial protein and the mechanism of solid-state fermentation with periodical dynamic changes

FU Xiaoguo, CHEN Hongzhang, LI Hongqiang, MA Runyu

期刊论文

Solid-state NMR for metal-containing zeolites: From active sites to reaction mechanism

Xingling Zhao, Jun Xu, Feng Deng

期刊论文

State-of-the-art applications of machine learning in the life cycle of solid waste management

期刊论文

A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

期刊论文

Phase transition regulation and caloric effect

期刊论文

Covalent triazine framework with efficient photocatalytic activity in aqueous and solid media

Cyrine Ayed, Wei Huang, Kai A. I. Zhang

期刊论文

一种低电流纹波的低压大电流DC-DC变换器的研究

王萍,孙栩,宋良瑜

期刊论文