Accurate Power Sharing in Proportion for Parallel Connected Inverters by Reconstructing Inverter Output Impedance

Shengli Huang,Jianguo Luo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents parallel-connected inverters to achieve accurate proportional power sharing. Due to line impedance mismatch, reactive power cannot be distributed proportionally when using the conventional P-ω and Q-E droop. In order to realize reactive proportional power sharing, the ratio of the droop coefficients should be inversely proportional to their power-sharing ratios. Meanwhile, the ratio of the line impedance should be inversely proportional to the desired power-sharing ratio, which is very difficult to be met in practice. In order to deal with this issue, a practical control strategy is presented. By measuring the PCC voltage and using the virtual impedance, the output impedance of individual inverters is reconstructed to counteract the line impedance effect. In order to guarantee system stability, a low pass filter is designed to suppress the bandwidth of the line compensation. Finally, the simulation and experimental results are given to verify the effectiveness of the proposed control strategy.

Multi-Function Distributed Generation with Active Power Filter and Reactive Power Compensator

Shengli Huang,Jianguo Luo 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

Accurate Power Sharing in Proportion for Parallel Connected Inverters by Reconstructing Inverter Output Impedance

Huang, Shengli,Luo, Jianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents parallel-connected inverters to achieve accurate proportional power sharing. Due to line impedance mismatch, reactive power cannot be distributed proportionally when using the conventional $P-{\omega}$ and $\mathcal{Q}-E$ droop. In order to realize reactive proportional power sharing, the ratio of the droop coefficients should be inversely proportional to their power-sharing ratios. Meanwhile, the ratio of the line impedance should be inversely proportional to the desired power-sharing ratio, which is very difficult to be met in practice. In order to deal with this issue, a practical control strategy is presented. By measuring the PCC voltage and using the virtual impedance, the output impedance of individual inverters is reconstructed to counteract the line impedance effect. In order to guarantee system stability, a low pass filter is designed to suppress the bandwidth of the line compensation. Finally, the simulation and experimental results are given to verify the effectiveness of the proposed control strategy.

Multi-Function Distributed Generation with Active Power Filter and Reactive Power Compensator

Huang, Shengli,Luo, Jianguo The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

Composition and diversity of ground-dwelling arthropods at Chiayi Agricultural long-term ecological research site in the Southern Taiwan

Sheng-Shan Lu,Shou-Horng Huang,Laleh Bordbar,I-Hsin Sung 국립중앙과학관 2019 Journal of Asia-Pacific Biodiversity Vol.12 No.4

In this study, the canola oil and alcohol were used as attractants in pitfall traps to help collect grounddwellingarthropods. Two small agricultural long-term ecological research fields at Chiayi AgriculturalExperimental Station were chosen to execute sampling activities. There were 14,509 individuals of 182species (including morphospecies) in 18 taxa in the collections. The most abundant taxon was Hymenoptera,followed by Coleoptera, Collembola, Diptera, Orthoptera, and Acari. Regardless to the differenceof the sampling fields, canola oil trap was significantly attractive to ants (Formicidae, Hymenoptera). Onthe other hand, the alcohol trap was more effective in attracting the Coleoptera. According to the diversityanalysis, the results indicated that the diversity indexes were affected by the main effect forattractant. In addition, the interactions between the farming operation and samplings and between theattractant and samplings were also factors to influence the diversity of ground-dwelling arthropods inthe long-term ecological research site of Chiayi Station.

SERVICE QUALITY EVALUATION OF INTERNATIONAL LOGISTICS COMPANY

Sheng Teng Huang,EmrahBulut,OkanDuru,ShigeruYoshida 인하대학교 정석물류통상연구원 2012 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.10 No.3

The national logistics policy report published by Ministry of Land, Infrastructure and Tourism in 2011 proposes to establish international logistics strategy teams in 10 different regions around Japan to satisfy the increasing demand for advance transportation infrastructure and stay competitive in Asia Pacific. The globalization of world economies creates many opportunities as well as challenges for international logistics companies to gain more business chances in this changing environment. The purpose of this paper is to improve service quality of international logistics companies and explores the quality function deployment in terms of quality evaluation method. The logistics service is particularly characterized by offering a series of transport solution and including other logistics activities. The major customers of the logistics services are the industrial clients. The customer satisfaction is key managerial mission since the competitiveness is a growing issue in this industry. The quality function deployment is one of the unique procedures to expose the requirements of customer and transform them into managerial tasks by cross correlation analysis between requirements and technical measures. The empirical study is performed to investigate service quality of the logistics industry by focusing on a group of leading logistics companies.

miR-19b enhances osteogenic differentiation of mesenchymal stem cells and promotes fracture healing through the WWP1/Smurf2-mediated KLF5/β-catenin signaling pathway

Huang Yan,Xu Yongqiang,Feng Siyin,He Pan,Sheng Bing,Ni Jiangdong 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

Bone marrow mesenchymal stem cell (BMSC)-derived exosomes have been found to enhance fracture healing. In addition, microRNAs contributing to the healing of various bone fractures have attracted widespread attention in recent years, but knowledge of the mechanisms by which they act is still very limited. In this study, we clarified the function of altered microRNA-19b (miR-19b) expression in BMSCs in fracture healing. We modulated miR-19b expression via mimics/inhibitors in BMSCs and via agomirs in mice to explore the effects of these changes on osteogenic factors, bone cell mineralization and the healing status of modeled fractures. Through gain- and loss-of function assays, the binding affinity between miR-19b and WWP1/Smurf2 was identified and characterized to explain the underlying mechanism involving the KLF5/β-catenin signaling pathway. miR-19b promoted the differentiation of human BMSCs into osteoblasts by targeting WWP1 and Smurf2. Overexpression of WWP1 or Smurf2 degraded the target protein KLF5 in BMSCs through ubiquitination to inhibit fracture healing. KLF5 knockdown delayed fracture healing by modulating the Wnt/β-catenin signaling pathway. Furthermore, miR-19b enhanced fracture healing via the KLF5/β-catenin signaling pathway by targeting WWP1 or Smurf2. Moreover, miR-19b was found to be enriched in BMSC-derived exosomes, and treatment with exosomes promoted fracture healing in vivo. Collectively, these results indicate that mesenchymal stem cell-derived exosomal miR-19b represses the expression of WWP1 or Smurf2 and elevates KLF5 expression through the Wnt/β-catenin signaling pathway, thereby facilitating fracture healing.

Performance Improvement of Offline Phase for Indoor Positioning Systems Using Asus Xtion and Smartphone Sensors

Sheng-Cheng Yeh,Yih-Shyh Chiou,Huan Chang,Wang-Hsin Hsu,Shiau-Huang Liu,Fuan Tsai 한국통신학회 2016 Journal of communications and networks Vol.18 No.5

Providing a customer with tailored location-based ser-vices (LBSs) is a fundamental problem. For location-estimationtechniques with radio-based measurements, LBS applications arewidely available for mobile devices (MDs), such as smartphones,enabling users to run multi-task applications. LBS information notonly enables obtaining the current location of an MD but also pro-vides real-time push-pull communication service. For indoor envi-ronments, localization technologies based on radio frequency (RF)pattern-matching approaches are accurate and commonly used. However, to survey radio information for pattern-matching ap-proaches, a considerable amount of time and work is spent in in-door environments. Consequently, in order to reduce the system-deployment cost and computing complexity, this article proposesan indoor positioning approach, which involves using Asus Xtionto facilitate capturing RF signals during an offline site survey. Thedepth information obtained using Asus Xtion is utilized to estimatethe locations and predict the received signal strength (RF informa-tion) at uncertain locations. The proposed approach effectively re-duces not only the time and work costs but also the computing com-plexity involved in determining the orientation and RF during theonline positioning phase by estimating the user’s location by usinga smartphone. The experimental results demonstrated that morethan 78% of time was saved, and the number of samples acquiredusing the proposed method during the offline phase was twice asmuch as that acquired using the conventional method. For the on-line phase, the location estimates have error distances of less than2.67 m. Therefore, the proposed approach is beneficial for use invarious LBS applications.

Preparation and Characterization of Proton Conductive Phosphosilicate Membranes Based on Inorganic-Organic Hybrid Materials

Sheng-Jian Huang,Hoi-Kwan Lee,Won-Ho Kang* 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.2

A series of proton conductive inorganic-organic hybrid membranes doped with phosphoric acid (H3PO4 ) and/or triethylphosphate (PO(OEt)3) have been prepared by sol-gel process with 3-glycidoxypropyltrimethoxy- silane (GPTMS), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0´103 S/cm with composition of 50TEOS- 0GPTMS-20APTES-50H3PO4 was obtained at 120 ºC under 50% relative humidity. Thermal stability of membrane was significantly enhanced by the presence of SiO2 framework up to 250 ºC. XRD revealed that the gels are amorphous. IR spectra showed a good complexation of H3PO4 in the matrix. The conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in concentration of defected site in hybrid matrix. The effect of PO(OEt)3, humidifying time, and heat-treatment were also investigated. PO(OEt)3 had no improvement on conductivity and conductivity increased with humidifying time, however, decreased with heating temperature.

The microstructure evolution and mechanical properties of ammonium polyphosphate/ aluminium hydroxide/ mica during thermal reaction

Sheng HU,Fei Chen,Jun-Guo Li,Qiang Shen,Zhi-Xiong Huang,Lian-Meng Zhang 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.8

The phase and microstructure evolution of ammonium polyphosphate/ aluminium hydroxide/ mica compounds (AAM) duringthermal reaction are investigated. At 300 oC, AAM residues exhibit porous structure due to gas evolution from the thermaldecomposition of ammonium polyphosphate (APP) and aluminium hydroxide, but mica does not react with them, and theflexural strength of specimens can reach 11.56 MPa. The thermal decomposition products of APP react with AlOOH toNH4AlP2O7, which can improve the flexural strength during 300 ~ 400 oC. The reactivity of mica is increased by eliminatinghydroxyl at temperature up to 600 oC, and the flexural strength of AAM residues is improved furtherly by the chemicallyinteractions between active mica and phosphates during 600 ~ 1000 oC. And specifically at 1000 oC, the AAM residues exhibitrelatively high flexural strength, which can reach 26.85 MPa and reactions between mica and KAlP2O7 could generateKAlSi3O8 and 3Al2O3·2SiO2. AAM with high flexural strength from low to high temperatures is expected to be a kind ofexcellent inorganic additive of ceramifiable polymer with wide temperature range for using.