Analysis and Application of Repetitive Control Scheme for Three-Phase Active Power Filter with Frequency Adaptive Capability

Biaoguang Sun,Yunxiang Xie,Hui Ma,Li Cheng 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.3

Active power filter (APF) has been proved as a flexible solution for compensating the harmonic distortion caused by nonlinear loads in power distribution power systems. Digital repetitive control can achieve zero steady-state error tracking of any periodic signal while the sampling points within one repetitive cycle must be a known integer. However, the compensation performance of the APF would be degradation when the grid frequency varies. In this paper, an improved repetitive control scheme with frequency adaptive capability is presented to track any periodic signal with variable grid frequency, where the variable delay items caused by time-varying grid frequency are approximated with Pade approximants. Additionally, the stability criterion of proposed repetitive control scheme is given. A three-phase shunt APF experimental platform with proposed repetitive control scheme is built in our laboratory. Simulation and experimental results demonstrate the effectiveness of the proposed repetitive control scheme.

Learning Multiple-Gait Quadrupedal Locomotion via Hierarchical Reinforcement Learning

Lang Wei,Yunxiang Li,Yunfei Ai,Yuze Wu,Hao Xu,Wei Wang,Guoming Hu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.9

Over long periods of evolution, legged animals have developed the capability to use a variety of gaits to move efficiently and flexibly at different speeds. To enable quadruped robots to acquire this ability, this study proposes a two-stage training hierarchical framework that can have quadruped robots generate energy-efficient multiple-gait locomotion, consisting of a gait selection policy module and a react controller module. The parameters of both modules are optimized using reinforcement learning. The experimental results in the simulation demonstrate that the proposed method can generate energy-efficient multiple-gait quadrupedal locomotion compared to previous methods. To validate the robustness and effectiveness of the method, we constructed a closed-chain quadruped robot and deployed the controller trained by the method to the robot. The experimental results in the real world suggest that the controller can enable the robot to move stably and efficiently in different gaits. The main contribution of this paper is that the authors propose a novel hierarchical framework, which makes quadruped robots use an optimal gait at a specific speed and smoothly switch to another one after getting a different speed command. These behaviors are automatically produced through simulation training, eliminating the need for the tedious work of designing gaits and modulating controllers. Experimental results showcase that the proposed method has significant advantages compared to previous methods.

A Novel Image Completion Algorithm Based on Planar Features

( Mang Xiao ),( Yunxiang Liu ),( Li Xie ),( Qiaochuan Chen ),( Guangyao Li ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.8

A novel image completion method is proposed that uses the advantage of planar structural information to fill corrupted portions of an image. First, in estimating parameters of the projection plane, the image is divided into several planes, and their planar structural information is analyzed. Second, in calculating the a priori probability of patch and patch offset regularity, this information is converted into a constraint condition to guide the process of filling the hole. Experimental results show that the proposed algorithm is fast and effective, and ensures the structure continuity of the damaged region and smoothness of the texture.

Investigation of Metro Train-Induced Environmental Vibration Using a Coupled Sliced Finite Element-Infinite Element Model

Longxiang Ma,Yunxiang Yu,Hongyi Li,Hao Yang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.6

A coupled sliced finite element-infinite element model is developed to analyse the train-induced environmental vibration from metro tunnel by treating the tunnel-ground system as a longitudinal periodic structure. Based on the auxiliary periodic train-track coupling model, this model enables one to select any periodic spatial range of the tunnel-ground system to analyse the response of the longitudinally infinite spatial domain, which will significantly enhance the computational efficiency. Unlike the existing 2.5D models and periodic models accounting for the train-induced environmental vibration, the significant reduction of the degrees of freedom of system in this model does not require a wavenumber transformation, thus only the formation knowledges of system governing equation in the normal space domain rather than in the transformed domain are needed. By comparing the simulated results with the corresponding measured ones, the proposed model is well validated. The transmission features of the metro train-induced environmental vibration, together with the impact on the rail pad stiffness and train velocity on the metro train-induced environmental vibration are also detailed investigated using the proposed model, with some important issues that deserve but have failed to attract due attention clarified.

Analysis and Application of Repetitive Control Scheme for Three-Phase Active Power Filter with Frequency Adaptive Capability

Sun, Biaoguang,Xie, Yunxiang,Ma, Hui,Cheng, Li The Korean Institute of Electrical Engineers 2016 Journal of Electrical Engineering & Technology Vol.11 No.3

Active power filter (APF) has been proved as a flexible solution for compensating the harmonic distortion caused by nonlinear loads in power distribution power systems. Digital repetitive control can achieve zero steady-state error tracking of any periodic signal while the sampling points within one repetitive cycle must be a known integer. However, the compensation performance of the APF would be degradation when the grid frequency varies. In this paper, an improved repetitive control scheme with frequency adaptive capability is presented to track any periodic signal with variable grid frequency, where the variable delay items caused by time-varying grid frequency are approximated with Pade approximants. Additionally, the stability criterion of proposed repetitive control scheme is given. A three-phase shunt APF experimental platform with proposed repetitive control scheme is built in our laboratory. Simulation and experimental results demonstrate the effectiveness of the proposed repetitive control scheme.

Carbon Source Affects Synthesis, Structures, and Activities of Mycelial Polysaccharides from Medicinal Fungus Inonotus obliquus

( Huihui He ),( Yingying Li ),( Mingyue Fang ),( Tiantian Li ),( Yunxiang Liang ),( Yuxia Mei ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.6

The effects of various carbon sources on mycelial growth and polysaccharide synthesis of the medicinal fungus Inonotus obliquus in liquid fermentation were investigated. After 12-d fermentation, mycelial biomass, polysaccharide yield, and polysaccharide content were significantly higher in Glc+Lac group (glucose and lactose used as combined carbon source) than in other groups. Crude polysaccharides (CIOPs) and the derivative neutral polysaccharides (NIOPs) were obtained from mycelia fermented using Glc, fructose (Fru), Lac, or Glc+Lac as carbon source. Molecular weights of four NIOPs (termed as NIOPG, NIOPF, NIOPL, and NIOPGL) were respectively 780.90, 1105.00, 25.32, and 10.28 kDa. Monosaccharide composition analyses revealed that NIOPs were composed of Glc, Man, and Gal at different molar ratios. The NIOPs were classified as α-type heteropolysaccharides with 1→2, 1→3, 1→4, 1→6 linkages in differing proportions. In in vitro cell proliferation assays, viability of RAW264.7 macrophages was more strongly enhanced by NIOPL or NIOPGL than by NIOPG or NIOPF, and proliferation of HeLa or S180 tumor cells was more strongly inhibited by NIOPG or NIOPGL than by NIOPF or NIOPL, indicating that immune-enhancing and antitumor activities of NIOPs were substantially affected by carbon source. qRT-PCR analysis revealed that expression levels of phosphoglucose isomerase (PGI) and UDP-Glc 4-epimerase (UGE), two key genes involved in polysaccharide synthesis, varied depending on carbon source. Our findings, taken together, clearly demonstrate that carbon source plays an essential role in determining structure and activities of I. obliquus polysaccharides by regulating expression of key genes in polysaccharide biosynthetic pathway.

Three-dimensional dynamics of vortex-induced vibration of a pipe with internal flow in the subcritical and supercritical regimes

Jinlong Duan,Ke Chen,Yunxiang You,Renfeng Wang,Jinlong Li 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity v. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity v in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of v. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while v is beyond the critical value. Besides, the responses corresponding to different couples of m1 and m2 are obviously distinct from each other.

Effects of Bacillus subtilis KN-42 on Growth Performance, Diarrhea and Faecal Bacterial Flora of Weaned Piglets

Hu, Yuanliang,Dun, Yaohao,Li, Shenao,Zhao, Shumiao,Peng, Nan,Liang, Yunxiang Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.8

This research focused on the effects of different doses of Bacillus subtilis KN-42 on the growth performance, diarrhea incidence, faecal bacterial flora, and the relative number of Lactobacillus and Escherichia coli in faeces of weaned piglets to determine whether the strain can serve as a candidate antimicrobial growth promoter. A total of 360 piglets (initial body weight $7.14{\pm}0.63$ kg) weaned at $26{\pm}2$ days of age were randomly allotted to 5 treatment groups (4 pens per treatment with 18 pigs per pen) for a 28-day trial. Dietary treatments were basal diet without any antimicrobial (negative control; NC), basal diet supplemented with 120 mg/kg feed of neomycin sulfate (positive control; PC) and basal diet supplemented with $2{\times}10^9$ (L), $4{\times}10^9$ (M) and $20{\times}10^9$ (H) CFU/kg feed of B. subtilis KN-42. During the overall period, average daily gain and feed efficiency of piglets were higher in groups PC, M, and H than those in group NC (p<0.05), and all probiotics and antibiotics groups had a lower diarrhea index than group NC (p<0.05). The 16S rDNA gene-based methods were used to analyze faecal bacterial flora on day 28 of experiment. The result of denaturing gradient gel electrophoresis analysis showed that supplementation of B. subtilis KN-42 to the diet changed the bacterial communities, with a higher bacterial diversity and band number in group M than in the other four groups. Real-time polymerase chain reaction analysis showed that the relative number of Lactobacillus were higher in groups PC and H than in group NC (p<0.05), and the supplemented B. subtilis KN-42 to the diet also reduced the relative number of E. coli (p<0.05). These results suggest that dietary addition of B. subtilis KN-42 can improve the growth performance and gastrointestinal health of piglets.

Precise Modeling and Adaptive Feed-Forward Decoupling of Unified Power Quality Conditioners

Yingpin Wang,Rubangakene Thomas Obwoya,Zhibo Li,Gongjie Li,Yi Qu,Zeyu Shi,Feng Zhang,Yunxiang Xie 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

The unified power quality conditioner (UPQC) is an effective custom power device that is used at the point of common coupling to protect loads from voltage and current-related PQ issues. Currently, most researchers have studied series unit and parallel unit models and an idealized transformer model. However, the interactions of the series and parallel converters in AC-link are difficult to analyze. This study utilizes an equivalent transformer model to accomplish an electric connection of series and parallel converters in the AC-link and to establishes a precise unified mathematical model of the UPQC. The strong coupling interactions of series and parallel units are analyzed, and they show a remarkable dependence on the excitation impedance of transformers. Afterward, a feed-forward decoupling method based on a unified model that contains the uncertainty components of the load impedance is applied. Thus, this study presents an adaptive method to estimate load impedance. Furthermore, simulation and experimental results verify the accuracy of the proposed modeling and decoupling algorithm.

Three-dimensional dynamics of vortex-induced vibration of a pipe with internal flow in the subcritical and supercritical regimes

Duan, Jinlong,Chen, Ke,You, Yunxiang,Wang, Renfeng,Li, Jinlong The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.6

The Three-dimensional (3-D) dynamical behaviors of a fluid-conveying pipe subjected to vortex-induced vibration are investigated with different internal flow velocity ${\nu}$. The values of the internal flow velocity are considered in both subcritical and supercritical regimes. During the study, the 3-D nonlinear equations are discretized by the Galerkin method and solved by a fourth-order Runge-Kutta method. The results indicate that for a constant internal flow velocity ${\nu}$ in the subcritical regime, the peak Cross-flow (CF) amplitude increases firstly and then decrease accompanied by amplitude jumps with the increase of the external reduced velocity. While two response bands are observed in the In-line (IL) direction. For the dynamics in the lock-in condition, 3-D periodic, quasi-periodic and chaotic vibrations are observed. A variety of CF and IL responses can be detected for different modes with the increase of ${\nu}$. For the cases studied in the supercritical regime, the dynamics shows a great diversity with that in the subcritical regime. Various dynamical responses, which include 3-D periodic, quasi-periodic as well as chaotic motions, are found while both CF and IL responses are coupled while ${\nu}$ is beyond the critical value. Besides, the responses corresponding to different couples of ${\mu}_1$ and ${\mu}_2$ are obviously distinct from each other.