Modeling and Control Design of Dynamic Voltage Restorer in Microgrids Based on a Novel Composite Controller

Huang, Yonghong,Xu, Junjun,Sun, Yukun,Huang, Yuxiang The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.6

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zero-steady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

Modeling and Control Design of Dynamic Voltage Restorer in Microgrids Based on a Novel Composite Controller

Yonghong Huang,Junjun Xu,Yukun Sun,Yuxiang Huang 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.6

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zerosteady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

Experimental and numerical investigation on bearing mechanism and capacity of new concrete plug structures

Yonghong Weng,Shuling Huang,Tangjin Xu,Yuting Zhang 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.24 No.5

The stability and safety of concrete plug structure of diversion tunnel is crucial for the impoundment of upstream reservoir in hydropower projects. The ongoing Wudongde hydropower plant in China plans to adopt straight column plugs and curved column plugs to replace the traditional expanded wedge-shaped plugs. The performance of the proposed new plug structures under high water head is then a critical issue and attracts the attentions of engineers. This paper firstly studied the joint bearing mechanism of plug and surrounding rock mass and found that the quality and mechanical properties of the interfaces among plug concrete, shotcrete, and surrounding rock mass play a key role in the performance of plug structures. By performing geophysical and mechanical experiments, the contact state and the mechanical parameters of the interfaces were analyzed in detail and provide numerical analysis with rational input parameters. The safety evaluation is carried out through numerical calculation of plug stability under both construction and operation period. The results indicate that the allowable water head acting on columnar plugs is 3.1 to 7.4 times of the designed water head. So the stability of the new plug structure meets the design code requirement. Based on above findings, it is concluded that for the studied project, it is feasible to adopt columnar plugs to replace the traditional expanded wedge-shaped plugs. It is hoped that this study can provide reference for other projects with similar engineering background and problems.

Preparation of Silica Nanoparticles via Two-Step Process Utilizing Mixed Chlorosilane Residues

Su, Yonghong,Xu, Bugang,Cai, Jixiang,Chen, Liang,Huang, Bing The Korean Ceramic Society 2018 한국세라믹학회지 Vol.55 No.6

We propose an economic and facile method for the preparation of silica nanoparticles through a two-step process utilizing chlorosilane residues. Mixed chlorosilane residue was alcoholized with absolute ethanol as a first step to form tetraethoxysilane (TEOS). The TEOS was then utilized as a silicon source to synthesize silica nanoparticles in a sol-gel method. The alcoholysis process was designed and optimized utilizing the Taguchi experimental design method and the yield of TEOS was as high as 82.2% under optimal synthetic conditions. Similarly, the Taguchi method was also utilized to study the effects of synthesis factors on the particle size of silica nanoparticles. The results of statistical analysis indicate that the concentration of ammonia has a greater influence on particle size compared to the mass fractions of TEOS and polyethylene glycol (4.6% and 9.7%). The purity of the silica particles synthesized in our experiments is high, but the specific surface area and pore volume are small.

Mathematical Modeling and Control for A Single Winding Bearingless Flywheel Motor in Electric/Suspension Mode

Yuan Ye,Huang Yonghong,Xiang Qianwen,Sun Yukun 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

With the increase of the production of energy from renewable, it becomes important to look at techniques to store this energy. Therefore, a single winding bearingless flywheel motor (SWBFM) specially for flywheel energy storage system is introduced. For the control system of SWBFM, coupling between the torque and the suspension subsystems exists inevitably. It is necessary to build a reasonable radial force mathematical model to precisely control SWBFM. However, SWBFM has twelve independently controlled windings which leads to high-order matrix transformation and complex differential calculation in the process of mathematical modeling based on virtual displacement method. In this frame, a Maxwell tensor modeling method which is no need the detailed derivation and complex theoretical computation is present. Moreover, it possesses advantages of universality, accuracy, and directness. The fringing magnetic path is improved from straight and circular lines to elliptical line and the rationality of elliptical line is verified by virtual displacement theory according to electromagnetic torque characteristics. A correction function is taken to increase the model accuracy based on finite element analysis. Simulation and experimental results show that the control system of SWBFM with radial force mathematical model based on Maxwell tensor method is feasible and has high precision.

Optimal design of micro-nano displacement driving mechanism for obtaining mechanical properties of micro structure

Biao Wang,Yan Huang,Yonghong Wang,Peizheng Yan,Qiaosheng Pan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

The mechanical structures of micro-electro-mechanical systems (MEMS) are composed of different types of microstructures, and their mechanical properties are very important for the realisation and reliability of the system performance. One of the key problems in measuring the mechanical properties is the design and implementation of micro-nano displacement driving mechanisms. This paper describes a mechanism that adopts a two-level loading strategy, fast approach, and precise bending displacement loading structures, and has a theoretical analysis and optimal design based on optimal targets of resistance and displacement. The results show that the relative error is 6.98 % for the fast-approaching structure experiment and its optimal simulation and 4.26 % for the precise bending displacement loading structure (PBLS) experiment and its optimal simulation. The optimised micro-nano displacement loading mechanism can achieve optimal output performance under existing constraints.

Conserved co-functional network between maize and Arabidopsis aid in the identification of seed defective genes in maize

Xiangbo Zhang,Yang Cui,Juxuan Wang,Yonghong Huang,Yongwen Qi 한국유전학회 2021 Genes & Genomics Vol.43 No.5

Background The biological pathways related to Arabidopsis seed development have been well studied and functional genes involved in it have been discovered. However, functional studies about maize seed development were more limited compared to Arabidopsis. Objective Therefore, transferring knowledge from Arabidopsis into maize would facilitate functional studies about maize seed development. Method In this study, public transcriptome data of the two species related to seed development were obtained. Co-expression network in each species was compared by integrating orthology information. Results This conserved co-functional network contained 4510 maize and 4808 Arabidopsis genes, respectively. Most of these genes were expressed in throughout embryo, early or later endosperm/seed. These conserved co-functional genes were signifcantly enriched for members of PPR protein family, which was consistent with that PPR proteins play an important role in maize seed development. Spatial-temporally co-functional genes were discovered in the seed coat and embryo. Furthermore, 66 well-studied genes involved in Arabidopsis seed development were co-functional with 319 maize genes and one maize gene (GRMZM2G036050) was further confrmed using an EMS-induced seed defective mutant by bulked segregating RNA sequencing (BSR) analysis. Conclusions Altogether, these results showed the potential of this approach to support functional studies in maize seed development by transferring knowledge from Arabidopsis.

Paranasal Sinus Invasion in Nasopharyngeal Carcinoma after Intensity-Modulated Radiotherapy

Caineng Cao,Feng Jiang,Qifeng Jin,Ting Jin,Shuang Huang,Qiaoying Hu,Yuanyuan Chen,Yongfeng Piao,Yonghong Hua,Xinglai Feng,Xiaozhong Chen 대한암학회 2019 Cancer Research and Treatment Vol.51 No.1

Purpose The aim of this study is to evaluate the prognostic significance of paranasal sinus invasion for nasopharyngeal carcinoma (NPC) and its suitable position in the T classification. Materials and Methods The magnetic resonance imaging (MRI) scans of 695 patients with previously untreated, biopsy-proven, non-metastatic NPC that was treated with intensity-modulated radiotherapy (IMRT) were reviewed retrospectively. Results The incidence of paranasal sinus invasion was 39.4% (274 of 695 patients). Multivariate analysis showed that paranasal sinus invasion was an independent negative prognostic factor for local failure-free survival (LFFS) (p < 0.05). According to the eighth American Joint Committee on Cancer (AJCC) staging system, 275 patients were classified as T3 classification. Of these, 78 patients (28.4%) developed paranasal sinus invasion (T3b) and 197 (71.6%) didn’t (T3a). The estimated 5-year LFFS and overall survival (OS) rates for the patients with T3b and T3a classification were 88.6% versus 95.0% (p=0.047), and 84.5% versus 93.3% (p=0.183), respectively. The estimated 5-year LFFS and OS rates for the patients with T4 classification were 89.5% and 83.2%, which were similar with the outcomes of patients with T3b classification. Conclusion MRI-determined paranasal sinus invasion is an independent prognostic factor of NPC treated by IMRT. Paranasal sinus invasion is recommended to classify as T4 classification in the 8th AJCC staging system for NPC.

Studies on Tissue Culture and Cryopreservation Germplasm of Papaya

JI Wu Zeng,Gan Jun Yi,Qiu Ming Zhang,Bi Rong Zhou,Yuan li Wu,Yonghong Hong Huang 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-