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Power Balance for Voltage-controlled PV Generator without Robust Voltage Source
Wang Zhenxiong,Zhuo Fang,Lv Nian,Yi Hao,Wu Jiaqi,Yan Hui,Ma Zekun 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Voltage control mode is preferable because of better bus voltage support and low reliance on communication. However, that is difficult to implement on photovoltaic inverter without robust voltage source. Meanwhile, photovoltaic arrays have some power management ability that usually neglected due to the use of MPPT, which in fact damages balanced power flow and a robust and stable grid. As a result, control of dc and ac side of photovoltaic inverter is usually separated and broken, where the dc side is usually supposed as an ideal voltage source and the corresponding relationships are neglected. This paper proposes a control scheme called photovoltaic generator for photovoltaic microgrid without robust voltage source, which imitates the principle of power conversion from mature synchronous generator theory. The scheme focuses on the active participation of solar energy in power management and voltage support. The effectiveness is verified in simulation and experiment.
Energy Management of Household Microgrid with Multiple Energy Resources for Rural Area
Hui Yan,Nian Lv,Fang Zhuo,Hao Yi,Zhenxiong Wang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The rural villages situated in the loess plateau of China often face with intermittency or even no electricity supply due to inconvenient geometrical location and enormous initial investment. However, renewable resources like solar energy are rich in such area, where microgrid with multiple energy resources is efficient for dealing with the power shortage. This paper proposes a scheme about hybrid household microgrid with multiple resources suitable for both islanded and grid-connected situations. The microgrid integrates photovoltaic, batteries and gasoline generator in source side and constructs AC and DC buses for different load requirements. The possible operation modes are analyzed and energy management strategies are proposed correspondingly. Finally, the microgrid platform has been established in laboratory. Several cases have been tested in experiment and energy management strategies in both islanded and grid-connected situations show good performance. Experimental results verify effectivity of this microgrid scheme and validation of proposed energy management strategies.
Yan-chao Wang,Jin-miao Lu,Hui-zi Jin,Ai-niu Ma,Jin-yang Zhang,Nian Gong,Qi Xiao,Bin Zhu,Ying-fang Lv,Na Yu,Wei-dong Zhang,Yong-xiang Wang 한국영양학회 2014 Nutrition Research and Practice Vol.8 No.2
BACKGROUND: Groundwater is believed to possess many beneficial effects due to its natural source of various minerals. In this study, we examined the effects of natural Jeju groundwater S1 (SamdasooTM), S2 and S3 pumped up from different locations of Jeju Island, Korea, along with local tap water, on body weight gain, serum lipids and lipoproteins, and liver histopathology in high-fat diet-induced hyperlipidemic rats. MATERIALS/METHODS: Rats were randomly and equally divided into 6 groups. Different water samples were supplied to the hyperlipidemic rats as their daily drinking water and the widely-used anti-hyperlipidemic drug simvastatin was used as a positive control. Body weight, serum lipids and lipoproteins were measured weekly. Liver weight, liver index and liver histopathology were examined after the execution of the rats. RESULTS: After drinking Jeju groundwaters for two months, S2 but not S3 significantly reduced weight growth and serum triglycerides levels and increased high density lipoprotein-C (HDL-C) without affecting total cholesterol or LDL-C. S1 and particularly S2 significantly reduced the severity of liver hypertrophy and steatosis. All Groundwaters had much higher contents of vanadium (S3>S2>S1>>tap water) whereas S1 and S2 but not S3 markedly blocked autoxidation of ferrous ions. CONCLUSION: Jeju Groundwater S1 and particularly S2 exhibit protective effects against hyperlipidemia and fatty liver and hypothesize that the beneficial effect of Jeju Groundwaters may be contributed from blockade of autoxidation of ferrous ions rather than their high contents of vanadium.
Factors for Postoperative Gallstone Occurrence in Patients with Gastric Cancer: a Meta-analysis
Chen, Xiang-Jun,Li, Nian,Huang, Ying-De,Ren, Shuang,Liu, Fang,Chen, Lian,Wang, Yong,Chen, Min Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.2
Objective: To evaluate risk factors for gallstones after gastrectomy. Methods: To identify documents published from 1990 to 2011 the Pubmed, Cochrane Library, Springer Link, CBM and WanFang databases were searched and a meta-analysis was performed with RevMan 5.2 software for odds ratios and 95%CIs. Results: Fifteen studies were selected for the meta-analysis. The pooled ORs [95%CIs] were 0.56 [0.43, 0.73], (P<0.0001) for digestive tract reconstruction, 0.80 [0.54, 1.17], (P=0.25) for pylorus preservation, 0.33[0.15, 0.75], (P=0.008) for resection scope of stomach, 0.33 [0.15, 0.75], (P=0.008) for lymphadenectomy, and 0.13 [0.05, 0.33], (P<0.0001) for vagotomy. Conclusions: Digestive tract physical reconstruction and vagus nerve preservation can reduce the morbidity of gallstones after gastrectomy. Total gastrectomy can add to the morbidity of galltones as does increasing the degree of lymph node dissection. There was no significant difference in gallstones with or without pylorus preservation.