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Transient stability enhancement of DC-connected DFIG and its converter system using fault protective device

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Journal of Modern Power Systems and Clean Energy 2017年第6期5卷 887-896页

作者： shaomin yan Aimin ZHANG Hang ZHANG Jianhua WANG Bin CAI School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina School of Engineering Qufu Normal UniversityRizhaoChina School of Electronic and Information Engineering Xi’an Jiaotong UniversityXi’anChina

Transient stability of doubly-fed induction generators(DFIGs)is a major concern in both AC and DC grids,and DFIGs must stay connected for a time during grid faults according to the power grid *** this purpose,this work proposes an overcurrent and overvoltage protective device(OCV-PD)to ensure that DCbased DFIG system can stay connected and operate well during the *** with a series dynamic braking resistor(SDBR),two aspects are ***,a twolevel control strategy and DC inductor circuit are used to ensure that the OCV-PD can limit the current impulse to protect DFIG system during an overcurrent ***,the OCV-PD can protect system from overvoltage fault which a SDBR cannot *** results verify itsvalidity and feasibility,finding that for overcurrent protection the OCV-PD outperforms a SDBR with an average decreased index of 3.29%,and for overvoltage protection it achieves an average index of 1.02%.

关键词： Transient stability Doubly-fed induction generator(DFIG) Overcurrent and overvoltage protective device(OCV-PD) DC grid Series dynamic braking resistor(SDBR)

维普期刊数据库

Optimized and coordinated model predictive control scheme for DFIGs with DC-based converter system

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 620-630页

作者： shaomin yan Aimin ZHANG Hang ZHANG Jianhua WANG Bin CAI School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina School of Electronic and Information Engineering Xi’an Jiaotong UniversityXi’anChina School of Engineering Qufu Normal UniversityRizhaoChina

This paper proposes an optimized and coordinated model predictive control(MPC) scheme for doublyfed induction generators(DFIGs) with DC-based converter system to improve the efficiency and dynamic performance in DC grids. In this configuration, the stator and rotor of the DFIG are connected to the DC bus via voltage source converters, namely, a rotor side converter(RSC) and a stator side converter(SSC). Optimized trajectories for rotorflux and stator current are proposed to minimize Joule losses of the DFIG, which is particularly advantageous at low and moderate torque. The coordinated MPC scheme is applied to overcome the weaknesses of the field-oriented control technique in the rotor flux-oriented frame, which makes the rotor flux stable and the stator current track its reference closely and quickly. Lastly, simulations and experiments are carried out to validate the feasibility of the control scheme and to analyze the steady-state and dynamic performance of the DFIG.

关键词： Coordinated model predictive control(MPC)scheme Doubly-fed induction generator(DFIG) DC-based converter system Optimized trajectories Rotor side converter(RSC) Stator side converter(SSC)

维普期刊数据库

不同含盐量的石灰粉煤灰固化石油污染土抗剪性能试验研究

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山东交通学院学报 2024年第2期32卷 33-41页

作者：郝中华牛皖豫安培磊闫少敏天津市交通科学研究院天津300300

为研究石油污染土的剪切特性,以不同含盐量的固化石油污染滨海盐渍土为研究对象,对石灰、粉煤灰稳定碎石固化石油污染土进行力学强度性能试验与微观分析。研究结果表明:随含盐量的增大,石灰粉煤灰固化石油污染土(简称污染土)的黏聚力和... 详细信息

为研究石油污染土的剪切特性,以不同含盐量的固化石油污染滨海盐渍土为研究对象,对石灰、粉煤灰稳定碎石固化石油污染土进行力学强度性能试验与微观分析。研究结果表明:随含盐量的增大,石灰粉煤灰固化石油污染土(简称污染土)的黏聚力和内摩擦角均先增大后减小;含盐量相同,污染土的黏聚力和内摩擦角均随石灰、粉煤灰质量分数的增大而先增大后减小,随石油质量分数的增大而减小;含盐量为1%,石油、粉煤灰、石灰质量分数分别为4%、20%、10%时,污染土的黏聚力和内摩擦角最大;污染土的应力-应变曲线在不同石灰、粉煤灰、石油质量分数下均先增大后减小并趋于稳定;不同含盐量下,污染土的微观结构特征和宏观土样抗剪强度参数的变化规律一致。

关键词：石油污染土石灰粉煤灰固化土滨海盐渍土抗剪强度微观结构

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Uptake of Polycyclic Aromatic Hydrocarbons across Bacterial Membrane

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Advances in Microbiology 2020年第7期10卷 331-348页

作者： shaomin yan Guang Wu State Key Laboratory of Non-Food Biomass and Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Polycyclic aromatic hydrocarbons (PAHs) are important pollutants, whose biodegradation and bioremediation with microorganisms are the promising ways to clean environments and reduce their exposure to humans. Although the transportation of PAHs across bacterial membrane is the first step forwards their biodegradation, it receives less attention. In this mini-review, we explore which transport system for uptake of carbon sources can serve for uptake of PAHs in bacteria, and try to uncover some patterns in their transport mechanisms. Collectively, 1) the major carbohydrate transport system, PTS, is unlikely to take PAHs because PAHs lack a hydroxy group for phosphorylation but aromatic acids are good candidates;2) PAHs could probably go through H+ symporters, especially the low-molecular-weight PAHs, which are partially dissolvable in water;3) it is unlikely that PAHs can produce chemiosmotic ion gradients to go through uniporters;and 4) antiporters could serve as transporters to transport PAHs across bacterial membrane only after the metabolism of PAHs generates extra H+ inside cell. Accordingly, the basic mechanism for uptake of PAHs is whether they can donate H+ in order to generate an electrochemical proton gradient to go through symporters.

关键词： Bacteria Polycyclic Aromatic Hydrocarbon Transport Mechanisms

Prediction of Mutations in H7 Hemagglutinins from Influenza A Virus

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Journal of Biomedical Science and Engineering 2020年第8期13卷 175-186页

作者： shaomin yan Guang Wu National Engineering Research Center for Non-Food Biorefinery State Key Laboratory of Non-Food Biomass and Enzyme Technology Guangxi Biomass Engineering Technology Research Center Guangxi Key Laboratory of Bio-Refinery Nanning China

Influenza A viruses have led several pandemics and epidemics in human history. H7 subtype influenza mainly infects avian but also humans occasionally. Since the outbreak of H7N9 subtype influenza occurred in China in 2013, this virus is still circulating in domestic poultry and leading several waves of influenza. To prevent influenza, vaccination is an important strategy. However, influenza virus evolves constantly, but unpredictably. If we would have a one-to-one cause-mutation relationship, the mutation prediction would be possible. However, many external causes, which led to the mutations in the past, might not leave any trace due to the change in environments, whereas the current virus might not be subject to the historically external causes because of evolution. Furthermore, the protein should have the internal causes, which might be quite unclear and difficult to quantify, to engineer mutations. Indeed, various forces twist proteins into 3-demensional structures, whereas any perturbation could lead to a mutation. Of various internal causes for mutation, randomness in protein primary structure should play an important role in mutation. Over years, we have developed three methods to quantify the randomness within a protein primary structure;thus we build a relationship between cause, which is randomness in primary structure, and mutations, which are occurrence and non-occurrence of mutation. In this way, the cause-mutation relationship becomes the problem of classification, which can be solved using logistic regression and neural network. In this study, we apply this model to predict 1) the mutation positions in H7 hemagglutinins from influenza A virus and 2) the would-be-mutated amino-acids at predicted positions with the amino-acid mutating probability. The results show suitability and predictability in such modelling, and pave the way for further development.

关键词： Hemagglutinin Influenza Mutation Neural Network Prediction Randomness

2-Dimensional HP Foldings of Dermaseptin-J2

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Engineering（科研） 2013年第10期5卷 78-84页

作者： shaomin yan Guang Wu State Key Laboratory of Non-Food Biomass Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Although the hydrophobic-polar (HP) model is a simple model to study protein folding, it is an approximation to the real-life case. Dermaseptin is a subfamily of frog skin active peptide family, which has various antimicrobial activities, and dermaseptin-J2 is a newly found peptide composed of 26 amino acids. In this study, the 2-dimensional HP model was used to analyze the foldings of dermaseptin-J2 and its nine mutants, which were converted to different HP sequences according to the normalized amino acid hydrophobicity index with respect to pH levels and the conversion of glycine as hydrophobic or polar, and each has 847,288,609,443 possible foldings. The results show that the foldings with minimal energy have different native states, which are chiral and can be numerically distinguished and ranked according to the normalized amino acid hydrophobicity index. The nine mutants of dermaseptin-J2 do not affect the minimal energy but affect their native states at pH 7. The results demonstrate that two pH levels and conversion of glycine as hydrophobic or polar affect the native state and minimal energy, suggesting these are two ways to modify dermaseptin-J2.

关键词： Dermaseptin Folding Configuration HP Model Hydrophobicity Index Minimal Energy Native State

Correlating Combined Features of Amino Acid and Protein with Crystallization Propensity of Proteins from <i>Mycobacterium tuberculosis</i>

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Journal of Biomedical Science and Engineering 2019年第9期12卷 427-442页

作者： shaomin yan Guang Wu National Engineering Research Center for Non-Food Biorefinery State Key Laboratory of Non-Food Biomass and Enzyme Technology Guangxi Key Laboratory of Bio-Refinery Guangxi Biomass Engineering Technology Research Center Guangxi Academy of Sciences Nanning China

Since a decade ago, both protein and amino acid features have been correlated with crystallization propensity of proteins in order to develop methods to predict whether a protein can be crystallized. In this continuing study, each of three features combining features of amino acid and protein, was correlated with the crystallization propensity of proteins from Mycobacterium tuberculosis using logistic and neural network models. The results showed that two combined features, amino acid distribution probability and future composition, had good predictions on whether a protein would be crystallized in comparison with the predictions obtained from each of 531 amino acid features. The results obtained from the third combined feature, amino acid pair predictability, demonstrated the trend of crystallization propensity in proteins from Mycobacterium tuberculosis.

关键词： Protein Feature Mycobacterium tuberculosis Protein Crystallization

Fitting of precipitation in 49 European capitals from 1901 to 1998 using random walk

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Natural Science 2011年第6期3卷 430-435页

作者： shaomin yan Guang Wu DreamSciTech Consulting Shenzhen Guangdong China

Mathematical modeling of precipitation is an important step to understand the precipitation patterns, and paves the way to possibly predict the precipitation. In this study, we attempt to use the random walk model to fit the annual precipitation in 49 European capitals from 1901 to 1998. At first, we used the simplest random walk model to fit the precipitation walk, which is the conversion of recorded precipitations into ±1 format, and then we used a more complex random walk model to fit the recorded precipi-tations. The results show that the random walk models can fit both precipitation walk and re-corded precipitation. Thus this study provides a model to describe the precipitation patterns during this period in these cities.

关键词： European Capital Fitting Precipitation Random Walk

Correlation of Combined Characters of Amino Acid and Whole Protein with Success Rate of Crystallization of <i>Lactobacillus</i>Proteins

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Journal of Biomedical Science and Engineering 2019年第4期12卷 245-256页

作者： shaomin yan Guang Wu State Key Laboratory of Non-food Biomass Enzyme Technology National Engineering Research Center for Non-Food Biorefinery Guangxi Key Laboratory of Biorefinery Guangxi Academy of Sciences Nanning China

Crystallization of proteins is a very delicate process, which is influenced by many known and unknown factors. Of tested factors, many factors are exclusively related to individual amino-acid characters such as molecular weight or protein characters such as protein length. It is considered necessary to test factors that combine both individual amino-acid characters and protein characters with respect to success rate of crystallization. In this study, two combined characters characterizing individual amino-acid character and protein character, amino acid distribution probability and future composition, were used to correlate the success rate of crystallization of proteins from Lactobacillus via modeling. The results obtained from logistic regression and neural network were compared against the results obtained from each of 533 individual amino-acid characters. This study demonstrated that the combined characters are involved in crystallization process and should be taken into account for predicting the success rate of crystallization process.

关键词： Amino Acid Character Distribution Probability Future Composition Lactobacillus Protein Crystallization