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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1950-1958页

作者： Tong Qian Qianlong Wei Zeyuan Yu Wenhu Tang qing-hua wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

This paper aims to develop an approach to investigating the effect of a particular parameter on the output accuracy of transformer thermal models,*** analysis,which can not only reveal the most sensitive parameter of a thermal model but also improve model output *** the first time,the nonlinear time constant(NTC)of transformer oil is proposed to reshape three practical top-oil temperature models based on an expression of nonlinear thermal conductance:the modified IEEE clause 7 model,Swift’s model,and Susa’s ***,the multi-parametric sensitivity analysis(MPSA)is undertaken to reveal the effect of each parameter on the model output *** onsite data validation,the results show that the accuracy performance of the proposed NTC thermal models are improved significantly by considering the nonlinear effect of oil time ***,the derived sensitivity performances can clearly reveal the most dominant parameter of the model,so as to simplify the model parameter identification process by reducing the number of insensitive ***,the heat-run test data is used as a reference to validate parameters optimized through a genetic algorithm(GA),which demonstrates that the proposed NTC IEEE model has not only one sensitive parameter but also superior accuracy performance.

关键词： Constant genetic algorithm multi-parametric sensitivity analysis nonlinear oil time transformer thermal model

Probabilistic Optimal Power Flow Considering the Dependence of Multiple Wind Farms Using Pair Diffusive Kernel Copula

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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1641-1654页

作者： Tianyao Ji Yantai Lin Yuzi Jiang Mengshi Li qing-hua wu the School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

As wind farms are commonly installed in areas with abundant wind resources,spatial dependence of wind speed among nearby wind farms should be considered when modeling a power system with large-scale wind *** this paper,a novel bivariate non-parametric copula,and a bivariate diffusive kernel(BDK)copula are proposed to formulate the dependence between random *** copula is then applied to higher dimension using the pair-copula method and is named as pair diffusive kernel(PDK)copula,offering flexibility to formulate the complicated dependent structure of multiple random ***,a quasi-Monte Carlo method is elaborated in the sampling procedure based on the combination of the Sobol sequence and the Rosen-blatt transformation of the PDK copula,to generate correlated wind speed *** proposed method is applied to solve probabilistic optimal power flow(POPF)*** effectiveness of the BDK copula is validated in copula ***,three different data sets are used in various goodness-of-fit tests to verify the superior performance of the PDK copula,which facilitates in formulating the dependence structure of wind speeds at different wind ***,samples obtained from the PDK copula are used to solve POPF problems,which are modeled on three modified IEEE 57-bus power *** to the Gaussian,T,and parametric-pair copulas,the results obtained from the PDK copula are superior in formulating the complicated dependence,thus solving POPF problems.

关键词： Bivariate diffusive kernel copula correlated wind speeds pair diffusive kernel copula probabilistic optimal power flow quasi-Monte Carlo Rosenblatt transformation

Stability Analysis of DC-DC Converters with Energy Balance Control

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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1765-1773页

作者： Lei Wang Yang Liu Yongliang Guo qing-hua wu Guangfu Tang School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China State Grid Smart Grid Research Institute Co. Ltd.Beijing 102209China

With variation of parameters,DC-DC converters may change from a stable state to an unstable state,which severely degrades the performances of the converter *** this article,by establishing the state-space average model,the stability and bifurcation of a boost and a buck-boost converter with energy balance control(EBC)is studied,*** the stability boundary and stable parameter domains are accurately *** obtained stability region provides a parameter regulating range for converter ***,compared with the one-cycle control(OCC)method,the EBC possesses an extended stable parameter domain,while avoiding unstable behaviors such as Hopf bifurcation,Quasi-periodic Oscillation even chaos,*** theoretic analysis is well validated through simulation and experiment.

关键词： DC-DC converter energy balance control average model slow-scale stability

Many-objective Optimization Method Based on Dimension Reduction for Operation of Large-scale Cooling Energy Systems

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CSEE Journal of Power and Energy Systems 2023年第3期9卷 884-895页

作者： Peng Zhu Lixiao Wang Cuiqing wu Jinyu Yu Zhigang Li Jiehui Zheng qing-hua wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

Large-scale cooling energy system has developed well in the past ***,its optimization is still a problem to be tackled due to the nonlinearity and large scale of existing *** the scale of problems without oversimplifying the actual system model is a big challenge *** paper proposes a dimension reduction-based many-objective optimization(DRMO)method to solve an accurate nonlinear model of a practical large-scale cooling energy *** the first stage,many-objective and many-variable of the large system are pre-processed to reduce the overall scale of the optimization *** relationships between many objectives are analyzed to find a few representative *** control variables are extracted to reduce the dimension of variables and the number of equality *** the second stage,the manyobjective group search optimization(GSO)method is used to solve the low-dimensional nonlinear model,and a Pareto-front is *** the final stage,candidate solutions along the Paretofront are graded on many-objective levels of system *** candidate solution with the highest average utility value is selected as the best running *** are carried out on a 619-node-614-branch cooling system,and results show the ability of the proposed method in solving large-scale system operation problems.

关键词： Dimension reduction group search optimization large-scale cooling energy system many-objective optimization

Transient Stability Analysis of Large-scale Power Systems:A Survey

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CSEE Journal of Power and Energy Systems 2023年第4期9卷 1284-1300页

作者： qing-hua wu Yuqing Lin Chao Hong Yinsheng Su Tianhao Wen Yang Liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China the Power Dispatching and Control Center China Southern Power GridGuangzhou 510530China

Transient stability analysis is a key problem in power system operation and *** paper aims at giving a comprehensive review on the modeling ideas and analysis methods for transient stability of large-scale power *** model construction,the general modeling of traditional power systems and special modeling for renewable generations and high-voltage direct-current transmissions are *** transient stability analysis,Lyapunov based methods and non-Lyapunov based methods are thoroughly *** Lya-punov based methods,we focus on the energy function method,the sum-of-squares based method and decentralized stability analysis ***,in non-Lyapunov based methods,the time-domain simulation,extended equal-area criterion and data-driven based methods are *** basic working principles,features and recent research progresses of all the above-mentioned methods are described in *** particular,their performances on several aspects,such as computational speed,conservativeness of stability region estimation or stability margin calculation,and adaptability to various types of system models,are ***,a brief discussion of potential directions for future research on transient stability analysis of large-scale power systems is *** Terms-connective stability,large-scale system analysis,Lyapunov functions,power systems,transient stability analysis.

关键词： connective stability large-scale system analysis Lyapunov functions power systems transient stability analysis

Generation maintenance scheduling based on multiple objectives and their relationship analysis

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Journal of Zhejiang University-Science C(Computers and Electronics) 2014年第11期15卷 1035-1047页

作者： Jun-peng ZHAN Chuang-xin GUO qing-hua wu Lu-liang ZHANG Hong-jun FU College of Electrical Engineering Zhejiang University Department of Electrical Engineering and Electronics University of Liverpool Liverpool L69 3GJ UK School of Electric Power Engineering South China University of Technology Power Dispatch and Control Center Henan Electric Power Company

In a market environment of power systems, each producer pursues its maximal profit while the independent system operator is in charge of the system reliability and the minimization of the total generation cost when generating the generation maintenance scheduling(GMS). Thus, the GMS is inherently a multi-objective optimization problem as its objectives usually conflict with each other. This paper proposes a multi-objective GMS model in a market environment which includes three types of objectives, i.e., each producer's profit, the system reliability, and the total generation cost. The GMS model has been solved by the group search optimizer with multiple producers(GSOMP) on two test systems. The simulation results show that the model is well solved by the GSOMP with a set of evenly distributed Pareto-optimal solutions obtained. The simulation results also illustrate that one producer's profit conflicts with another one's, that the total generation cost does not conflict with the profit of the producer possessing the cheapest units while the total generation cost conflicts with the other producers' profits, and that the reliability objective conflicts with the other objectives.

关键词： Generation maintenance scheduling Market environment Multi-objective optimization

Procyanidin B2 protects against diet-induced obesity and non-alcoholic fatty liver disease via the modulation of the gut microbiota in rabbits

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World Journal of Gastroenterology 2019年第8期25卷 955-966页

作者： Ya-Wei Xing Guang-Tao Lei qing-hua wu Yu Jiang Man-Xiang huang Department of Gastroenterology The Second Xiangya HospitalCentral South UniversityChangsha 410011Hunan ProvinceChina Department of Cardiovascular Medicine The Second Affiliated Hospital of Nanchang UniversityNanchang 330006Jiangxi ProvinceChina

BACKGROUND Procyanidins have beneficial effects on metabolic syndrome and antimicrobial activity,but the mechanisms underlying these effects are *** To investigate the effects of procyanidin B2(PB2)on non-alcoholic fatty liver disease and to explore the possible *** Thirty male New Zealand white rabbits were randomized into three *** of them were fed either a high-fat-cholesterol diet(HCD)or chow ***-fed rabbits were treated with vehicle or PB2 daily for 12 *** weight and food intake were evaluated once a *** biomarkers,such as total cholesterols,triglycerides,and aspartate transaminase,were *** rabbits were sacrificed and histological parameters of liver were assessed by hematoxylin and eosin-stained ***,several lipogenic genes and gut microbiota(by 16S rRNA sequencing)were investigated to explore the possible *** The HCD group had higher body weight,liver index,serum lipid profile,insulin resistance,serum glucose,and hepatic steatosis compared to the CHOW ***2 treatment prevented HCD-induced increases in body weight and hypertriglyceridemia in association with triglyceride accumulation in the ***2 also ameliorated low-grade inflammation,which was reflected by serum lipopolysaccharides and improved insulin *** rabbit liver,PB2 prevented the upregulation of steroid response element binding protein 1c and fatty acid synthase and the downregulation of carnitine palmitoyltransferase,compared to the HCD ***,HCD led to a decrease of Bacteroidetes in gut ***2 significantly improved the proportions of Bacteroidetes at the phylum level and Akkermansia at the genus *** Our results indicate the possible mechanism of PB2 to improve HCD-induced features of metabolic syndrome and provide a new dietary supplement.

关键词： Procyanidin Rabbit Non-alcoholic fatty liver disease Gut microbiota 16S rRNA

Control and Stability of Large-scale Power System with Highly Distributed Renewable Energy Generation:Viewpoints from Six Aspects

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CSEE Journal of Power and Energy Systems 2023年第1期9卷 8-14页

作者： qing-hua wu Anjan Bose Chanan Singh Joe H.Chow Gang Mu Yuanzhang Sun Zhaoxi Liu Zhigang Li Yang Liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China School of Electrical Engineering&Computer Science Washington State UniversityPullmanWA 99164USA Department of Electrical and Computer Engineering Texas A&M UniversityCollege StationTX 77843USA Department of Electrical Computer and Systems EngineeringRensselaer Polytechnic Institute(RPI)TroyNYUSA Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin 132012China School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China

Power systems are moving toward a low-carbon or carbon-neutral future where high penetration of renewables is *** conventional fossil-fueled synchronous generators in the transmission network being replaced by renewable energy generation which is highly distributed across the entire grid,new challenges are emerging to the control and stability of large-scale power *** analysis and control methods are needed for power systems to cope with the ongoing *** the CSEE JPES forum,six leading experts were invited to deliver keynote speeches,and the participating researchers and professionals had extensive exchanges and discussions on the control and stability of power ***,potential changes and challenges of power systems with high penetration of renewable energy generation were introduced and explained,and advanced control methods were proposed and analyzed for the transient stability enhancement of power grids.

关键词： Distributed energy resources high converter penetration power system control renewable energy generation stability control transient stability

Peripheral leukocyte count and risk of bleeding in patients with non-valvular atrial fibrillation taking dabigatran: a real-world study

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Chinese Medical Journal 2019年第18期132卷 2150-2156页

作者： Wei Zhou Tao Wang Ling-Juan Zhu Ming-hua Wen Li-hua Hu Xiao huang Chun-Jiao You Ju-Xiang Li Yan-qing wu qing-hua wu Hui-Hui Bao Xiao-Shu Cheng Center for Prevention and Treatment of Cardiovascular Diseases The Second Affiliated Hospital of Nanchang University Nanchang Jiangxi 330006 China Department of Cardiovascular Medicine The Second Affiliated Hospital of Nanchang University Nanchang Jiangxi 330006 China

Background: The association between peripheral leukocyte count and bleeding events in nonvalvular atrial fibrillation (NVAF) patients treated with dabigatran remains unclear. This study aimed to explore the association between leukocyte count and bleeding events after excluding other confounders in NVAF patients taking dabigatran. Methods: A total of 851 NVAF patients treated with dabigatran (110 mg bid) were recruited from 12 centers in China from February 2015 to December 2017. Follow-up was completed by May 2018. The exposure and outcome variables were leukocyte count measured at baseline and the number of bleeding events within the subsequent 6 months. Multivariate Cox proportional hazards models were constructed to analyze independent associations, and a Cox proportional hazards regression with cubic spline functions and smooth curve fitting (penalized spline method) was used to address nonlinearity between leukocyte count and bleeding. The inflection point was calculated using a recursive algorithm, and then a two-piecewise Cox proportional hazards model for both sides of the inflection point was constructed. Results: During 6-month follow-up, 87 participants occurred bleeding events. For every 1×10^9/L increase in leukocyte count, the risk of bleeding increased by 11%(hazard ratio [HR]: 1.11, 95% confidence interval [CI]: 0.99–1.25). The smooth curve showed nonlinear relationship between leukocyte count and bleeding events. The inflection point of the leukocyte count was 6.75×10^9/L. For leukocyte counts < 6.75×10^9/L, the HR (95% CI) was 0.88 (0.69–1.13), and for leukocyte counts ≥ 6.75×10^9/L, the HR (95% CI) was 1.28 (1.09–1.51). Conclusion: This study found a J-shaped association between baseline leukocyte count and risk of bleeding in NVAF patients treated with dabigatran.

关键词： Peripheral leukocyte count Bleeding Nonvalvular atrial fibrillation Threshold effect

Ventilatory effect of normal frequency jet ventilation in non-intubated anesthesia in the treatment of the palmar hyperhidrosis

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Journal of Hainan Medical University 2019年第7期25卷 25-29页

作者： Shu-Rong Li qing-hua wu Chun-Lan Lin Yao-hua Yu Department of Anesthesiology Fisrt Hospital of PutianPutian351100Fujian ProvinceChina

Objective: To evaluate the ventilatory effect of normal frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the palmar hyperhidrosis (PH). Methods: 62 patients with PH undergoing video-assisted thoracoscopic sympathectomy, aged 18~35 years, ASA I-II, were randomized into two groups: intubated group (group T) and normal-frequency jet ventilation group (group J). After induction tracheal tubes were inserted in Group T and Wei nasal airway were inserted in group J. The heart rate(HR),saturation pulse oxygen (SPO2), mean artery pressure (MAP) and end-tidal carbon dioxide partial pressure (PETCO2) were recorded at following time points: before induction (T0),1 min after induction (T1), 1 min after tube insertion/ intubation (T2), when trocars were inserted and carbon dioxide was inflated (T3), during lung recruitment maneuver and the chest closure (T4), the moment of extubation (T5), 15 min after extubation (T6). Blood samples were taken from left radial artery for blood gas analysis to monitor carbon dioxide partial pressure, arterial oxygen partial pressure, PH ,the BE at T0, T4, *** duration of anesthesia, awaking time ,the dosage of the propofol and the remifentanil, the intraoperative and postoperative adverse events were recorded. Results: Compared with group T, the HR and MAP were more stable in group J. The awaking time in the group J were significantly shorter than those in group T (P<0.05), the dosage of the remifentanil in group J was significantly less than that in group T (P<0.05), The incidences of throat discomfort, nausea and vomiting were lower than those in group T (P<0.05). Conclusion: Normal-frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the (PH)is feasible, which can reduce stress response and make hemodynamics stable without the complications of tracheal intubation.

关键词： Non-intubation Supraglottic Normal-frequency jet ventilation Wei jet nasal airway Thoracic sympathectomy