Chopper Controller Based DC Voltage Control Strategy for Cascaded Multilevel STATCOM

Xiong, Lian-Song,Zhuo, Fang The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.2

The superiority of CMI (Cascaded Multilevel Inverter) is unparalleled in high power and high voltage STATCOM (Static Synchronous Compensator). However, the parameters and operating conditions of each individual power unit composing the cascaded STATCOM differ from unit to unit, causing unit voltage disequilibrium on the DC side. This phenomenon seriously impairs the operation performance of STATCOM, and thus maintaining the DC voltage balance and stability becomes critical for cascaded STATCOM. This paper analyzes the case of voltage disequilibrium, combines the operation characteristics of the cascaded STATCOM, and proposes a new DC voltage control scheme with the advantages of good control performance and stability. This hierarchical control method uses software to achieve the total active power control and also uses chopper controllers to enable that the imbalance power can flow among the capacitors in order to keep DC capacitor voltages balance. The operating principle of the chopper controllers is analyzed and the implementation is presented. The major advantages of the proposed control strategy are that the number of PI regulators has been decreased remarkably and accordingly the blindness of system design and debugging also reduces obviously. The simulation reveals that the proposed control scheme can achieve the satisfactory control goals.

Chopper Controller Based DC Voltage Control Strategy for Cascaded Multilevel STATCOM

Lian-Song Xiong,Fang Zhuo 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.2

The superiority of CMI (Cascaded Multilevel Inverter) is unparalleled in high power and high voltage STATCOM (Static Synchronous Compensator). However, the parameters and operating conditions of each individual power unit composing the cascaded STATCOM differ from unit to unit, causing unit voltage disequilibrium on the DC side. This phenomenon seriously impairs the operation performance of STATCOM, and thus maintaining the DC voltage balance and stability becomes critical for cascaded STATCOM. This paper analyzes the case of voltage disequilibrium, combines the operation characteristics of the cascaded STATCOM, and proposes a new DC voltage control scheme with the advantages of good control performance and stability. This hierarchical control method uses software to achieve the total active power control and also uses chopper controllers to enable that the imbalance power can flow among the capacitors in order to keep DC capacitor voltages balance. The operating principle of the chopper controllers is analyzed and the implementation is presented. The major advantages of the proposed control strategy are that the number of PI regulators has been decreased remarkably and accordingly the blindness of system design and debugging also reduces obviously. The simulation reveals that the proposed control scheme can achieve the satisfactory control goals.

Structural Damage Identification Based on Improved Fruit Fly Optimization Algorithm

Chunbao Xiong,Sida Lian 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.3

To locate the damage of the structure efficiently and judge the damage degree, this paper proposes an improved fruit fly optimization algorithm (IFOA). Aiming at the problem of poor convergence of the standard fruit fly optimization algorithm in the face of complex structure damage identification, the IFOA introduces the concept of collaborative search of two subpopulations. The IFOA divides the entire population into positive subgroups and negative subgroups based on the individual taste concentration results. Among them, the positive subgroup uses the improved dynamic adaptive search step size to perform a fine search locally to improve its local search ability. Negative subgroups continue to use the standard fruit fly optimization algorithm for optimization, taking advantage of the powerful global search capabilities of the standard fruit fly optimization algorithm. It enables the algorithm to balance global and local search capabilities, prevents the algorithm from falling into local optimum, and speeds up the convergence speed and accuracy of the algorithm. Simulation results show that IFOA can effectively identify the damage location and damage degree of the structure, and it still performs well when facing the complex steel truss damage identification.

Detection and Location of Steel Structure Trestle Surface Cracks Based on Consumer-grade Camera System

Chunbao Xiong,Sida Lian,Wen Chen 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.3

Because the steel structure trestle has been in service under heavy load for a long time, the steel structure trestle is prone to cracks around the welds or bolt holes, which can lead to structural collapse in severe cases. Aiming at the characteristics of stable and high-quality images obtained by the unmanned consumer-grade camera monitoring system, this paper proposed structure health monitoring (SHM) system which is based on consumer-grade camera. The SHM system can identify crack damage and locate steadily in long term, which provides the technical support of practical application in intelligent SHM system. The method first performed edge detection on the trestle structure, followed by pixel-level semantic segmentation and crack localization. Canny edge detection algorithm was used to identify trestle structures in the camera image. The panorama trestle structure was divided into areas of suitable size, and the camera focused on each divided area one by one. Then the improved DeepLab V3+ model was trained by constructing global and local datasets. Then the improved DeepLab V3+ model was used to perform pixel-level semantic segmentation on the trestle images of the divided regions. Finally, based on the Speeded Up Robust Features and combined with the image, a panorama crack location output method was proposed. The system was used to test a section of a trestle in a coal mining industrial park, and the system showed that the method could efficiently and accurately identify and locate the crack damage.

Effect of Contact Pressure on Reciprocating Wear Behavior of PEEK, PTFE, and UHMWPE

Liu Lian,Duan Haitao,Jia Dan,Tu Jiesong,Zhan Shengpeng,Li Yinhua,Luo Xiaoshuang,Zhan Wen,Xiong Wei,Li Jian 한국고분자학회 2020 폴리머 Vol.44 No.6

Engineering plastics are macromolecular compounds composed of covalently bonded macromolecules, which have been widely used in sliding wear-resistance materials in isolation bearings. In this study, an MFT-5000 reciprocating friction testing machine was used to compare the friction and wear performance of polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), and ultra-high molecular weight polyethylene (UHMWPE) under heavy load conditions in dry friction condition. The results show that load has a significant effect on the friction coefficient, wear rate, and wear mechanism of three materials. The instant friction coefficient of PTFE fluctuates under high load, the wear rate clearly increases with the increase in load. Therefore, the application under high load conditions is limited. The wear rate of UHMWPE is the least affected by the load among the three materials. Even when the load exceeds the yield strength, the wear resistance is still good. The friction coefficient of PEEK decreases with the increase in load but maintains a high value that restricts its application in sliding friction pair materials to some degree.

Dietary Vitamin E Influences the Levels of Nitric Oxide and Cytokines in Broiler Chickens

Xu, Jian-Xiong,Chen, Xiao-Lian,Wang, Jing,Wang, Tian Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.10

The study investigated the effects of dietary Vitamin E (VE) on nitric oxide (NO) metabolism, immune function and analyzed the correlation between NO free radical and cytokines (IL-2 and IL-6) in broilers. One hundred and fifty 2-week-old broilers were randomly divided into three groups. Control group and lower VE ($VE^-$) group were provided with a basic diet supplemented with 12.55 mg/kg VE and 2.55 mg/kg VE for 30 days, respectively. Higher VE ($VE^{-}-VE^+$) group was supplemented with 2.55 mg/kg VE in the first 15 days and then 32.55 mg/kg VE in the next 15 days. Five broilers in each group were then sacrificed on the 5th, 10th, 15th, 20th, 25th and 30th days, respectively, and the content of NO free radical, superoxide dismutase (SOD), glutathione peroxidase (GSHPx), malondialdehyde (MDA) and cytokines, IL-2 and IL-6, were measured. The results showed that lower VE could decrease growth performance of broilers while higher VE could increase growth performance and eliminate differences resulted from feeding lower VE dietary in early stages (p<0.05). Compared with the control group, lower VE could increase significantly NO and MDA concentration, and increase IL-2 concentration in serum (p<0.05). Higher VE could significantly increase activities of SOD and glutathione GSH-Px (p<0.05). IL-2 is positively correlated with NO in heart (p<0.05) and IL-6 is negatively correlated with NO in liver (p<0.05) and heart (p<0.01). These results indicate that dietary VE could regulate antioxidant capacity and NO metabolism of broilers and higher VE-supplemented diet could directly decrease production of IL-2.

Preparation and characterization of epoxidized microbial oil

Xinde Chen,Dan Yang,Lian Xiong,Bo Wang,Xuefang Chen,Can Wang,Hairong Zhang,Haijun Guo 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.3

The potential of microbial oil derived from yeasts through fermentation using crops biomass for the formation of plasticizers was investigated. Plasticizers were formed via epoxidation reaction. Five factors of the orthogonal experiment (reaction temperature, time, weight ratio of H2O2/MO, H2SO4/MO, and HCOOH/MO) have been used for optimization of parameters. To further enhance the iodine value of microbial oil and increase the epoxy value of the epoxide, an amount of soybean oil was added. The products were characterized by FTIR, 13C-NMR and 1H-NMR. Under the optimum condition, the epoxy value and the iodine value of epoxide product were 6.21% and 1.8 g I2/100 g with a yield of 91.86% at an oil conversion of 98.43%. This study successfully demonstrated the conversion of crops biomass into value-added chemicals using simple and conventional chemical reactions.

Study on Truth of Fire-heat Symptoms and Adverse Reaction of Panax ginseng

Dong-Hwi Kim(김동휘),Xiong Jun(熊俊),Lian Xue Zhang(張連學),Yong Hua Xu(許永貨),Young Chang Kim(김영창),Kyong Hwan Bang(방경환),Jang Uk Kim(김장욱),Seon Woo Cha(차선우),In Bok Chang(장인복),Lin Li(林勵) 한국약용작물학회 2015 한국약용작물학회 학술대회논문집 Vol.2015 No.1

The relationship between the variants in the 5'-untranslated regions of equine chorionic gonadotropin genes and serum equine chorionic gonadotropin levels

ShuQin Liu,Song Lian,YunZhou Yang,ChunZheng Fu,HongYing Ma,ZhiYao Xiong,Yao Ling,ChunJiang Zhao 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.12

Objective: An experiment was conducted to study the association between the single nucleotide polymorphisms (SNPs) in 5'-untranslated regions (5'-UTR) of equine chorionic gonadotropin (eCG) genes and the serum eCG levels. Methods: SNPs in 5'-UTR of eCG genes were screened across 10 horse breeds, including 7 Chinese indigenous breeds and 3 imported breeds using iPLEX chemistry, and the association between the serum eCG levels of 174 pregnant Da’an mares and their serum eCG levels (determined with ELISA) was analyzed. Results: Four SNPs were identified in the 5'-UTR of the eCGα gene, and one of them was unique in the indigenous breeds. There were 2 SNPs detected at the 5’ end of the eCGβ subunit gene, and one of them was only found in the Chinese breeds. The SNP g.39948246T>C at the 5'-UTR of eCGα was associated significantly with eCG levels of 75-day pregnant mare serum (p<0.05) in Da’an mares. Prediction analysis on binding sites of transcription factors showed that the g.39948246T>C mutation causes appearance of the specific binding site of hepatocyte nuclear factor 3 forkhead homolog 2 (HFH-2), which is a transcriptional repressor belonging to the forkhead protein family of transcription factors. Conclusion: The SNP g.39948246T>C at the 5'-UTR of eCGα is associated with eCG levels of 75-day pregnant mare serum (p<0.05).

Phase II Clinical Study on the GEMOX Regimen as Second-line Therapy for Advanced Ovarian Cancer

Yuan, Shao-Fei,Zhang, Lian-Ping,Zhu, Lin-Jia,Chen, Wen-Jun,Zheng, Wei-E,Xiong, Jian-Ping Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6

Aim: To investigate the effectiveness and adverse effects of gemcitabine by fixed-dose rate infusion plus oxaliplatin (GEMOX regimen) as second-line therapy for advanced ovarian cancer. Methods: 64 patients with advanced ovarian cancer were divided into an experimental group (44 cases) and a control group (20 cases). The experimental group was treated with continuous intravenous infusion of gemcitabine at 1000 $mg/m^2$ with a fixed-dose rate of 10 $mg/m^2/min$, on days 1 and 8 and oxaliplatin at 100 $mg/m^2$ on day 1, IVGTT, repeated every 3 weeks. The control group was treated with intravenous infusion of gemcitabine at 1000 $mg/m^2$ within 30 min on days 1 and and oxaliplatin at 100 $mg/m^2$ on day 1, IVGTT, again repeated every 3 weeks. CT scans or MRI were used for review every 1-2 cycles. Results: The effective rate in the experimental group was significantly high than control group (43.2% vs 35.0%; P < 0.05), with no obvious difference of hematologic or non-hematologic toxicity between the two groups (P > 0.05). Conclusion: GEMOX regimen is very effective to treat advanced ovarian cancer, with low toxicity, good tolerance and improved life quality in patients.