检索结果-南通市图书馆

Equivalent Impedance Parameter Calculation of Three-phase Symmetrical Loads for Harmonic Source Location

在线全文

学校读者我要写书评

暂无评论

Journal of Modern power Systems and Clean Energy 2024年第1期12卷 251-260页

作者： Yi Zhang Bijie Liu Caihua Lin Zhenguo Shao Yuncong Xu the Department of electrical Engineering and Automation Fuzhou UniversityFuzhouChina State Grid Fujian electric power Research institute FuzhouChina

The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic ***,the existing calculation methods suffer from outliers caused by the zero-crossing of the *** outliers can result in inaccuracy and unreliability of harmonic source *** address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid *** correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring *** results show that the proposed method is not only simple and easy to implement but also highly accurate.

关键词： abc-αβtransformation equivalent impedance parameters of load harmonic source location nonlinear load power quality

Investigation on corrosion of yttrium-doped magnesium-based sacrificial anode in ground grid protection

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2010年第S1期28卷 389-392页

作者：冯拉俊闫爱军孟勇强侯娟玲 School of Materials Science and Engineering Xi'an University of Technology Shaanxi electric power Research institute North Western electric power design institute

In the simulated DC and AC discharge circuit in ground grid protection of substation,corrosion and potential of magnesium anode with yttrium addition were studied by potential measurement and scanning electron *** results showed that potential of anode increased with increasing current density in DC simulation,potential increase of anode with 0.1% yttrium addition was the smallest,and the affordable current density of the anode reached 1.85 A/cm2,which was two times that of the anode without yttrium *** AC simulation,addition of yttrium had less effect on its *** of magnesium alloy sacrificial anode without yttrium addition were the equiaxed grains of magnesium grains coated with β-Mg17Al12,while the anode with yttrium was α-Mg phase with dispersed β *** corroded magnesium anode with 0.1% yttrium addition showed the most uniform and the smallest pit on its surface.

关键词： yttrium magnesium anode ground grid rare earths

Galvanic Corrosion Behavior of Copper-Drawn Steel for Grounding Grids in the Acidic Red Soil Simulated Solution

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第11期33卷 1571-1582页

作者： Xiao-Lei Fan Yun-Xiang Chen Jun-Xi Zhang De-Yuan Lin Xuan-Xuan Liu Xiao-Jian Xia Shanghai Key Laboratory of Materials Protection and Advanced Materials in electric power Shanghai University of Electric PowerShanghai 200090China electric power Research institute of State Grid Fujian electric power Company Limited Fuzhou 350007China

The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated *** effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique *** steel is corroded as anode,while the corrosion of copper plate is protected as *** the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn *** the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red *** electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.

关键词： Cu-Fe galvanic couple Electrochemical test Scanning vibrating electrode technique(SVET)measurement Soil corrosion

Behavior of axially loaded tubular X-joints using bolted connection:mechanical model and validation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 880-889页

作者： Yong CHEN Ji-yang WANG Yong GUO Guo-hui SHEN Li-xian YANG Bin-nan SUN College of Civil Engineering and Architecture Zhejiang University Zhejiang electric power design institute

X-joints are one of the fundamental joint configurations used in a wide range of transmission tubular *** investigation of four tubular X-joints with bolted connection was conducted in this study,and it was found that the annular plate was the main yielding control member of such ***,the portion outside the effective width of the chord member still had a restriction effect on the annular plate,which led to reducing the yielding strength of the joint,while the gusset plate could help to improve the yield strength *** the current design code of steel structures,the contribution to the strength capacity of the gusset plate has not been taken into ***,based on some mechanical assumptions,a general mechanical model was *** the introduction of the gusset plate strength capacity factor,the yield capacity simplified calculation method of such X-joints was *** the analyses of such X-joints with various diameters and thicknesses,it was concluded that a simple mechanical model could predict test results very well and that the contribution of the gusset plate was also taken into account.

关键词： Steel tubular X-joint Bolted connection Annular plate Gusset plate Strength capacity

Numerical simulation of heat transfer and flow of cooling air in triangular wavy fin channels

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第7期21卷 2759-2765页

作者：倪明龙陈亚平董聪吴嘉峰 School of Energy and Environment Southeast University Jiangsu electric power design institute

Numerical computation models of air cooling heat transfer and flow behaviors in triangular wavy fin channels(TWFC) were established with structural parameters of fins *** air side properties of heat transfer coefficient and pressure drop are displayed with variable structural parameters of fins and inlet velocities of cooling *** the range of simulation,TWFC has the best comprehensive performance when inlet velocity vin=4-10 m/*** with those of straight fins,the simulation results reveal that the triangular wavy fin channels are of higher heat transfer performances especially with the fin structural parameters of fin-height Fh=9.0 mm,fin-pitch Fp=2.5-3.0 mm,fin-wavelength λ=14.0-17.5 mm and fin-wave-amplitude A=1.0-1.2 *** correlations of both heat transfer factor and friction factor are presented,and the deviations from the experimental measurements are within 20%.

关键词： triangular wavy fins heat transfer coefficients pressure drops plate-fin heat exchangers air cooling

Green heating:Theory and practice

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2015年第12期58卷 2003-2015页

作者： YANG YongPing LI PeiFeng GE ZhiHua TIAN Jia WANG NingLing SONG ZhiPing School of Energy power and Mechanical Engineering North China Electric Power University Beijing Municipal institute of City Planning & design

Energy conservation in heating systems has great influence on overall sustainable development strategy. Heating technology, especially combined heat and power(CHP, cogeneration), has been attracting increased interest and rapidly developing in recent years. However, the theoretical potential of heating from the perspective of thermodynamics has not been clearly illustrated. This paper presents a theoretical analysis of heating systems based on the 1st and 2nd laws of thermodynamics using the specific fuel consumption(SFC) analysis method, clarifies the theoretical potential limitation of heating systems and illustrates the process of reversible heating on the basis of the total energy system. A novel concept(green heating, GH) and a new indicator(green-heating index, GH Index) are scientifically defined to characterise different options for heating and to quantitatively evaluate their fuel consumption levels. Thereafter, the fuel consumptions of four typical space heating modes are compared and discussed to present the application of GH theory and validate the power of the proposed concept and index. Furthermore, two different CHP technologies are analyzed with an instantiation case, and a novel CHP system is recommended, which may scientifically support the development of heating technology and further improve the processes of energy-saving and CO2 reduction.

关键词： green heating combined heat and power space heating specific fuel consumption exergy thermodynamics

High Frequency Stability Constraints Based MMC Controller design Using NSGA-III Algorithm

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of power and Energy Systems 2023年第2期9卷 623-633页

作者： Ke Ji Weiming Chen Xueguang Wu Hui Pang Jingxuan Hu Shan Liu Fan Cheng Guangfu Tang China electric power Research institute Beijing 100192China Chen is with State Grid Fujian electric power Research institute Fuzhou 350007China State Grid Smart Grid Research institute Beijing 102211China

The occurrence of high frequency resonances(HFRs)has been frequently observed in several MMC-HVDC *** avoid these HFRs,the controller design of an MMC must satisfy two requirements:1)The controller should remain stable while in the high frequency range,and 2)MMC impedance should not possess a negative real part in the high frequency *** far,majority of the related studies on MMC controller design have been unable to address these requirements *** paper first describes the simplified high frequency MMC impedance model developed indigenously by the ***,the driving mechanism of two kinds of HFRs is revealed using the said developed model,including:1)MMC controller instability,and 2)Interaction instability between MMC and AC ***,the mathematical expressions outlining the controller stability constraint and positive damping constraint are ***,NSGA-III based multi-objective optimization algorithm is adopted,to identify the region most suitable for satisfying the proposed stability constraints under the MMC controller *** proposed controller design method is capable of effectively evading the HFRs triggered by the incompatible *** detailed time-domain simulations generated using PSCAD/EMTDC software validate the proposed designed method and endorse the improved results.

关键词： AC cable controller parameter optimization harmonic resonance MMC NSGA-III offshore wind power integration

Three-dimensional Numerical Study on Thermal Performance of a Super Large Natural Draft Cooling Tower of 220m Height

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2013年第3期22卷 234-241页

作者： JIN Tai ZHANG Li LUO Kun FAN Jianren State Key Laboratory of Clean Energy Utilization (Zhejiang University) Hunan electric power design institute

Based on the heat and mass transfer theory and the characteristics of general-purpose software FLUENT, a three-dimensional numerical simulation platform, composed of lots of user defined functions(UDF), has been developed to simulate the thermal performance of natural draft wet cooling towers(NDWCTs). After validation, this platform is used to analyse thermal performances of a 220m high super large cooling tower designed for inland nuclear plant under different operational conditions. Variations of outlet temperature of the cooling tower caused by changes of water flow rates, inlet water temperatures are investigated. Effects of optimization through non-uniform water distributions on outlet water temperature are discussed, and the influences on the flow field inside the cooling tower are analyzed in detail. It is found that the outlet water temperature will increase as the water flow rate increases, but the air flow rate will decrease. The outlet water temperature will decrease 0.095K and 0.205K, respectively, if two non-uniform water distribution approaches are applied.

关键词： Super Large Natural Draft Wet Cooling Tower Three-dimensional Numerical Simulation Thermal Performance Non-uniform Water Distribution

Data-driven Convexification for Frequency Nadir Constraint of Unit Commitment

在线全文

学校读者我要写书评

暂无评论

Journal of Modern power Systems and Clean Energy 2023年第5期11卷 1711-1717页

作者： Yukang Shen Wenchuan Wu Bin Wang Yue Yang Yi Lin State Key Laboratory of power Systems(Department of electrical Engineering) Tsinghua UniversityBeijing 100084China IEEE electric power Research institute Fujian Electric Power Ltd.CompanyFuzhou 350003China

The increasing penetration of the renewable energy sources brings new challenges to the frequency security of power systems. In order to guarantee the system frequency security, frequency constraints are incorporated into unit commitment(UC) models. Due to the non-convex form of the frequency nadir constraint which makes the frequency constrained UC(FCUC) intractable, this letter proposes a revised support vector machine(SVM) based system parameter separating plane method to convexify it. Based on this data-driven convexification method, we obtain a tractable FCUC model which is formulated as a mixed-integer quadratic programming(MIQP) problem. Case studies indicate that the proposed method can obtain less conservative solution than the existing methods with higher efficiency.

关键词： Unit commitment frequency constraint support vector machine(SVM) data-driven convexification