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Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC-DC voltage
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作者 金福宝 周远翔 +2 位作者 梁斌 周仲柳 张灵 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第5期14-22,共9页
Due to the complexity of the valve side winding voltage of the converter transformer,the insulation characteristics of the oil-impregnated pressboard(OIP)of the converter transformer are different from those of the tr... Due to the complexity of the valve side winding voltage of the converter transformer,the insulation characteristics of the oil-impregnated pressboard(OIP)of the converter transformer are different from those of the traditional AC transformer.The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC-DC voltage is seriously inadequate.Therefore,this paper investigates the characteristics of OIP creepage discharge under combined AC-DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70℃to 110℃.The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature.The times of low amplitude discharge(LAD)decrease and amplitude of LAD increases.Simultaneously,the times of high amplitude discharge(HAD)gradually in crease at each stage of creepage discharge with higher temperature.The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging.The residual charge carriers are more easily dissipated after discharging.The'hump'region of LAD moves to the direction of higher discharge magnitude.The interval time between two continuous discharges is shortened obviously.The concentration of HAD accelerates the development of OIP insulation creepage discharge.The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage. 展开更多
关键词 oil-impregnated PRESSBOARD INSULATION combined AC-DC VOLTAGE inception VOLTAGE CREEPAGE discharge temperature flashover VOLTAGE
Phase–amplitude model for doubly fed induction generators 预览
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作者 Hua HUANG Ping JU +3 位作者 Xueping PAN Yuqing JIN Xiaoming YUAN Yuan GAO 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第2期369-379,共11页
The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power sys... The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power system dynamics. However, most existing practical models of the DFIG are based on rectangular coordinates,in which frequency variation is neglected. In this paper, a phase-amplitude(P-A) model is proposed for a DFIG based on phase and amplitude of the internal voltage. The model structure is much like that of the synchronous generator, and the rotor voltage can manipulate both the amplitude and the phase of the internal voltage.Comparisons have been made between the new P-A model of the DFIG and the synchronous generator model,as well as the asynchronous motor model.The contributions of the new P-A model of the DFIG are discussed and it is demonstrated that the proposed model has better ability in describing power system dynamic phenomena such as voltage dynamics and structural dynamics. Simulation results and a field test validate these contributions. 展开更多
关键词 DOUBLY fed induction generator(DFIG) MODEL Internal VOLTAGE VOLTAGE DYNAMICS Frequency DYNAMICS
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Improved virtual synchronous control for grid-connected VSCs under grid voltage unbalanced conditions 预览
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作者 Lei SHANG Jiabing HU +1 位作者 Xiaoming YUAN Yunhui HUANG 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第1期174-185,共12页
This paper presents an improved virtual synchronous control(VSynC) for the grid-connected voltage source converter(VSC) so as to continuously operate under the grid voltage with steady unbalance.The improved VSynC int... This paper presents an improved virtual synchronous control(VSynC) for the grid-connected voltage source converter(VSC) so as to continuously operate under the grid voltage with steady unbalance.The improved VSynC introduces the negative sequence power controls on basis of conventional VSynC.The improved VSynC is capable of regulating the negative sequence internal voltage to reduce the negative-sequence injected currents and oscillated powers of the VSC aroused by the negative-sequence grid voltage.Three alternative local control objectives for the VSC itself under steady state unbalanced grid conditions and their corresponding power references are deduced and computed.Simulated and experimental results are presented to validate the correctness and effectiveness of the proposed improved VSynC to enhance the continuous operation performance of VSynC-based VSCs during grid voltage steady-state unbalance. 展开更多
关键词 Grid VOLTAGE UNBALANCE VIRTUAL SYNCHRONOUS control(VSynC) GRID-CONNECTED VOLTAGE source converter(VSC)
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Influence of test procedure on dielectric breakdown strength of alumina
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作者 Bjoern MIELLER 《先进陶瓷(英文版)》 CSCD 2019年第2期247-255,共9页
Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the ac... Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization. 展开更多
关键词 DIELECTRIC STRENGTH DIELECTRIC BREAKDOWN withstand VOLTAGE test high AC VOLTAGE testing
Design and analysis of a NMOS triggered LIGBT structure for electrostatic discharge protection 预览
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作者 Li Tian Jianbing Cheng +2 位作者 Cairong Zhang Li Shen Lei Wang 《半导体学报:英文版》 EI CAS CSCD 2019年第5期47-50,共4页
A novel NMOS triggered LIGBT(NTLIGBT) structure is proposed for electrostatic discharge(ESD) protection in this paper. The structure utilizes internal NMOS to trigger SCR-like structure in LIGBT. The trigger voltage i... A novel NMOS triggered LIGBT(NTLIGBT) structure is proposed for electrostatic discharge(ESD) protection in this paper. The structure utilizes internal NMOS to trigger SCR-like structure in LIGBT. The trigger voltage is significantly reduced because the embedded NMOS causes N+-drain/P-body junction being apt to avalanche breakdown. At the same time, the new parasitic PNP transistor including the newly added P+-region as a collector forms another path to bleed ESD current and then the conductivity modulation in the LIGBT is weakened. As a result, the holding voltage is increased. So, the proposed NTLIGBT structure has a narrow ESD design window. The simulation results show an improvement of 71.5% in trigger voltage and over 50% in holding voltage comparing with the conventional LIGBT structure. 展开更多
关键词 ESD NMOS triggered LIGBT(NTLIGBT) TRIGGER VOLTAGE holding VOLTAGE ESD design window
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Effect of UV radiation aging on creepage discharge characteristics of high temperature vulcanized silicon rubber at high altitude
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作者 金福宝 周远翔 +3 位作者 梁斌 梁曦东 周仲柳 张灵 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第5期23-33,共11页
The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The ex... The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then decreases.But the aging time has little effect on the creepage discharge inception voltage.With the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is accelerated.In the short time of applying voltage to aging material,the magnitude of discharge in creases rapidly.According to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four stages.Compared with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear trend.The study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage. 展开更多
关键词 HIGH temperature vulcanized silicone rubber CREEPAGE discharge UV AGING INCEPTION VOLTAGE FLASHOVER VOLTAGE HIGH altitude characteristic parameters
浅谈ISO11898汽车CAN总线电压测试 预览
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作者 马齐成 李销 《汽车实用技术》 2019年第17期72-74,共3页
随着电子技术在汽车上的广泛应用,汽车电子化程度越来越高。从发动机控制到传动系控制,从行驶、制动、转向系控制到安全保证系统以及仪表报警系统渐渐形成了一个复杂的大系统。整车厂大多时候将车载的电子控制单元(ECU)设计和生产外包... 随着电子技术在汽车上的广泛应用,汽车电子化程度越来越高。从发动机控制到传动系控制,从行驶、制动、转向系控制到安全保证系统以及仪表报警系统渐渐形成了一个复杂的大系统。整车厂大多时候将车载的电子控制单元(ECU)设计和生产外包给零部件生产商,整车集成期间电气系统被连成多个ECU、多节点的有机整体,使得其功能及性能更加完善。目前CAN总线作为国际上应用最为广泛的现场总线之一,以其优良的可靠性和稳定性获得用户的肯定,也被广泛应用于ECU间的通信连接。随着系统复杂度日益增加,其网络通信质量的可靠性要求变得日益突出。为了确保can总线的通信质量,CAN总线电压测试就排在首位。ISO11898标准中描述的CAN总线物理层一致性测试原理较为抽象,厂商在制定测试、执行测试过程中往往会遇到不少困难,这里主要是解读ISO 11898标准有关CAN物理层CAN总线电压测试项目。 展开更多
关键词 ISO 11898 CAN 电压 测试
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电解槽连接铜排的维护保养对节能降耗的影响 预览
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作者 陈烨莉 《氯碱工业》 CAS 2019年第4期21-22,27共3页
研究了实验室状态下铜排连接强度对电压的影响。利用力矩扳手分别对铜排进行紧固,得到了50,150,200,250和300N·m时实测试验铜排电压降。实验室试验证明:使用合适的紧固力度对连接铜排的紧固螺栓进行重新锁紧,可以降低非生产性消耗... 研究了实验室状态下铜排连接强度对电压的影响。利用力矩扳手分别对铜排进行紧固,得到了50,150,200,250和300N·m时实测试验铜排电压降。实验室试验证明:使用合适的紧固力度对连接铜排的紧固螺栓进行重新锁紧,可以降低非生产性消耗。按每台槽运行电流14kA计,2台电解槽每年可节约电费262080元。 展开更多
关键词 电解 铜排 温度 连接面积 电压
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两阶段频率和电压协调校正方法
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作者 许鹏飞 宋墩文 +2 位作者 杨铖 汤伟 马世英 《电网技术》 EI CSCD 北大核心 2019年第7期2561-2567,共7页
该文提出了利用模型预测控制(modelpredictive control,MPC)进行频率和电压协调校正的方法,以应对大规模直流馈入受端系统频率和电压失稳交织问题。在故障下利用模型仿真预测频率电压响应,同时利用数值法和直接法进行轨迹灵敏度的计算,... 该文提出了利用模型预测控制(modelpredictive control,MPC)进行频率和电压协调校正的方法,以应对大规模直流馈入受端系统频率和电压失稳交织问题。在故障下利用模型仿真预测频率电压响应,同时利用数值法和直接法进行轨迹灵敏度的计算,基于轨迹灵敏度建立协调滚动优化模型,并将控制量反馈回电网,形成闭环控制。提出了两阶段频率和电压协调校正方法,在第一阶段投入辅助决策,在第二阶段利用基于MPC的协调校正,通过闭环控制增加控制量直至频率和电压恢复至稳定运行水平。利用实际系统仿真数据对所提方法进行了测试。结果表明,基于MPC的协调校正方法能够通过对灵敏控制集的切负荷控制使频率和电压协调恢复至稳定运行水平。两阶段校正方法利用辅助决策快速投入加快了恢复速度,利用基于MPC的闭环控制有效的使频率和电压恢复至稳定运行水平。 展开更多
关键词 频率 电压 协调校正 模型预测控制 辅助决策
Simulation of a high-performance enhancement-mode HFET with back-to-back graded AlGaN layers
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作者 Fu PENG Chao YANG +4 位作者 Siyu DENG Dongya OUYANG Bo ZHANG Jie WEI Xiaorong LUO 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第6期87-97,共11页
A novel three-dimensional hole gas(3 DHG) enhancement-mode(E-mode) heterostructure fielde?ect transistor(HFET) is proposed and investigated. It features back-to-back graded AlGaN(BGA) barrier layers consisting of a po... A novel three-dimensional hole gas(3 DHG) enhancement-mode(E-mode) heterostructure fielde?ect transistor(HFET) is proposed and investigated. It features back-to-back graded AlGaN(BGA) barrier layers consisting of a positive-graded AlGaN layer and a negative-graded AlGaN layer, which form polarization gradient and subsequently induce the three-dimensional electron gas(3 DEG) and 3 DHG in the positiveand negative-graded AlGaN layers, respectively. The source and drain are located at the same side of the metal-insulator-semiconductor(MIS) trench gate, and the source is in contact with the HfO2 gate insulator.First, the on-state current is significantly improved owing to the high-density 3 DEG in the positive-graded AlGaN. Next, the vertical conductive channel between the source and 3 DEG is blocked by the 3 DHG, thereby realizing the E-mode. The threshold voltage(Vth) can be modulated by a partial doping conductive channel.Subsequently, a high breakdown voltage(BV) is obtained, because the polarization junction formed by the polarization charges assists in depleting the drift region in the o?-state. Next, the BGA-HFET is smaller than the conventional HFET(Con-HFET) owing to the special location of the source. The BV of the proposed HFET sharply increases to 919 V from 39 V of the Con-HFET with the same gate-drain spacing, and the saturation drain current is increased by 103.5%. 展开更多
关键词 GRADED ALGAN 3DHG-3DEG large on-state current high voltage enhancement mode
Development of 0.5-V Josephson junction array devices for quantum voltage standards
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作者 王兰若 李劲劲 +2 位作者 曹文会 钟源 张钟华 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第6期453-457,共5页
The design, fabrication, and the characterization of a 0.5-V Josephson junction array device are presented for the quantum voltage standards in the National Institute of Metrology(NIM) of China. The device consists of... The design, fabrication, and the characterization of a 0.5-V Josephson junction array device are presented for the quantum voltage standards in the National Institute of Metrology(NIM) of China. The device consists of four junction arrays, each of which has 1200 3-stacked Nb/NbxSi1-x/Nb junctions and an on-chip superconducting microwave circuit which is mainly a power divider enabling each Josephson array being loaded with an equal amount of microwave power. A direct current(dc) quantum voltage of about 0.5 V with a ~1-mA current margin of the 1 st quantum voltage step is obtained.To further prove the quality of NIM device, a comparison between the NIM device with the National Institute of Standards and Technology(NIST) programmable Josephson voltage standard(PJVS) system device is conducted. The difference of the reproduced 0.5-V quantum voltage between the two devices is about 0.55 nV, which indicates good agreement between the two devices. With the homemade device, we have realized a precise and applicable 0.5-V applicable-level quantum voltage. 展开更多
关键词 JOSEPHSON VOLTAGE standards JOSEPHSON JUNCTION superconducting-normal metal–superconducting(SNS) JUNCTION QUANTUM device
氧化石墨烯修饰碳纤维正极改进海水电池电压 预览
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作者 田国东 孙立娟 孙虎元 《电源技术》 CAS 北大核心 2019年第5期832-835,共4页
海水电池工作电压较高,电压平台平稳。通过不同电压电泳沉积氧化石墨烯的方法修饰碳纤维表面,以其为海水电池的正极材料。用青岛海域海水作电解液,分别测试用该材料正极构成的半电池与全电池性能,对比修饰前后的性能变化。结果表明:修... 海水电池工作电压较高,电压平台平稳。通过不同电压电泳沉积氧化石墨烯的方法修饰碳纤维表面,以其为海水电池的正极材料。用青岛海域海水作电解液,分别测试用该材料正极构成的半电池与全电池性能,对比修饰前后的性能变化。结果表明:修饰后碳纤维正极开路电位正移;单个电极可通过的电流密度有所提升,可通过3mA以内的电流同时保证电池拥有正常工作的电压;修饰后碳纤维与AZ63镁合金组成电池,无负载时电池电压最高达1.56V,恒阻放电时工作电压最高1.40V,均比未修饰时有所提高,工作电压也更稳定。 展开更多
关键词 碳纤维 正极材料 石墨烯 海水电池 电压
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Achieving high efficiency and low voltage loss simultaneously for non-fullerene organic solar cells
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作者 Liwei Yang Yanyan Jia He Yan 《中国科学:化学英文版》 SCIE EI CAS CSCD 2019年第4期405-406,共2页
Conventional organic solar cells are based on fullerene acceptors,which caused several drawbacks including poor absorption in visible and near IR regions,limited tunability of energy levels,and most importantly,large ... Conventional organic solar cells are based on fullerene acceptors,which caused several drawbacks including poor absorption in visible and near IR regions,limited tunability of energy levels,and most importantly,large voltage loss from the optical bandgap of the cell to the open circuit voltage of the solar cell[1].During the past few years,nonfullerene OSCs have emerged as a promising alternative to fullerene devices,as their optical and electronic properties can be readily tuned.Furthermore,it has been demonstrated in numerous cases that non-fullerene OSCs[2]can achieve small voltage loss of about 0.55 V,which is much improved compared to that of conventional devices.Achieving such a small voltage loss is of paramount importance to OSCs,as it indicates the maximum achievable efficiency of OSCs can be increased to nearly 20%. 展开更多
关键词 high EFFICIENCY low VOLTAGE LOSS SOLAR CELLS
基于数据包络分析的电压矢量控制方法 预览
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作者 陈军 《科学技术与工程》 北大核心 2019年第18期222-227,共6页
为了解决常用电压矢量控制方法需进行大量函数运算,在实际应用中较难实现,并且在实际应用中需分析电压矢量变化对电流控制的影响,需降低计算量,因此通过数据包络分析研究电压矢量控制问题。依据电压矢量控制电路图分析了电压矢量控制过... 为了解决常用电压矢量控制方法需进行大量函数运算,在实际应用中较难实现,并且在实际应用中需分析电压矢量变化对电流控制的影响,需降低计算量,因此通过数据包络分析研究电压矢量控制问题。依据电压矢量控制电路图分析了电压矢量控制过程,获取电压矢量控制的过程中需遵循的三个规则。通过最近三矢量法对参考矢量进行合成,获取不同区域中各电压矢量的作用时间,采用数据包络分析法对电压矢量进行控制时,需满足电压矢量作用时间约束。数据包络分析在各采样周期内,依据电压矢量控制规则与作用时间,将不同决策单元的输入权重与输出权重当成变量,从最有利于决策单元的角度对不同决策单元的有效性进行评估,获取电压矢量评估结果,选择最优电压矢量当成下一个周期的施加矢量,实现电压矢量控制。结果表明:所提方法在波形抖动方面的控制明显更稳定;在发生突变的情况下,所提方法可快速响应;电流畸变率一直处于最低水平。可见所提方法电压矢量控制优势显著,性能强。 展开更多
关键词 数据包络分析 电压 矢量控制 方法
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硅酸钠浓度对Ti3Al基合金微弧氧化层生长及其摩擦磨损性能的影响 预览
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作者 贾文婷 王文波 +4 位作者 田林海 王晓云 常勇强 张伟樯 聂勇 《表面技术》 EI CAS CSCD 北大核心 2019年第7期104-111,共8页
目的研究硅酸钠溶液浓度对Ti3Al基合金表面制备微弧氧化膜层结构的影响,以提高Ti3Al基合金微弧氧化膜层的摩擦磨损性能。方法采用恒流模式微弧氧化电源,分别在6、8、10g/L的Na2SiO3电解液中,对Ti3Al基合金试样进行微弧氧化处理,用扫描... 目的研究硅酸钠溶液浓度对Ti3Al基合金表面制备微弧氧化膜层结构的影响,以提高Ti3Al基合金微弧氧化膜层的摩擦磨损性能。方法采用恒流模式微弧氧化电源,分别在6、8、10g/L的Na2SiO3电解液中,对Ti3Al基合金试样进行微弧氧化处理,用扫描电子显微镜(SEM)、能谱仪(EDS)、ImageJ软件、X射线衍射仪(XRD)及显微硬度仪,分析微弧氧化膜层的表面形貌和截面形貌、元素分布、厚度、相组成以及表面硬度。用CFT-I型磨损试验机研究不同微弧氧化膜层的摩擦磨损性能。结果随着Na2SiO3浓度的增加,微弧氧化的工作电压与起弧电压均逐渐减小。微弧氧化层表面呈多孔状,存在熔融物堆积导致的环状凸起。随着Na2SiO3浓度的增加,氧化层表面微孔直径减小,膜层逐渐增厚。微弧氧化膜层主要Al2O3、SiO2、TiO2、Nb2O5以及Al2SiO5相组成,微弧氧化处理明显降低了Ti3Al基合金的摩擦系数和磨损率。电解液Na2SiO3质量浓度为10g/L时,微弧氧化膜层的平均摩擦系数为0.49,磨损率仅为2.1×10^-7mm^3/(N·mm),主要表现为微切削磨损与轻微的粘着磨损。结论随着硅酸钠浓度的增加,有利于提高微弧氧化膜层的形成速率,缩短反应时间。微弧氧化处理能够显著改善Ti3Al基合金的耐磨性。 展开更多
关键词 TI3AL基合金 微弧氧化 摩擦磨损 微弧氧化层 硅酸钠 电压
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WAMS中电压和无功连续数据的三维可视化显示方法 预览
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作者 董清 刘超 李龙发 《电力科学与工程》 2019年第5期12-18,共7页
电网广域测量系统的高速连续采样数据的直观显示技术,对于实时监视电网的安全稳定性具有重要意义。通过将一个采样点的电压相量幅值数据映射成绘制圆弧的半径,将该采样点的无功数据映射成绘制圆弧长度的弧心角,一个采样点的电压和无功... 电网广域测量系统的高速连续采样数据的直观显示技术,对于实时监视电网的安全稳定性具有重要意义。通过将一个采样点的电压相量幅值数据映射成绘制圆弧的半径,将该采样点的无功数据映射成绘制圆弧长度的弧心角,一个采样点的电压和无功数据被绘制成一段弧线,连续采样的电压和无功数据将被绘制成三维曲面,提出了一种电网中电压和无功连续数据的三维可视化绘图新方法。通过对比电动机的电压和无功数据的不同绘图方法的显示效果,以及以电网中短路故障和低频振荡扰动的仿真数据为例,验证了该方法具有以下特点:可将电压和无功的连续采样数据绘制成具有一定形状的图形,使电动机的电压失稳状态显示更直观;结合电网的结构图,使电网中故障点定位和低频扰动源定位实现了可视化直观显示。该方法对于电网中故障和扰动的快速连续直观显示,具有一定价值。 展开更多
关键词 电网 广域测量系统 电压 无功 可视化 电动机稳定性 短路故障定位 低频振源定位
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Research on Online Monitoring Methods on SF6 Circuit Breakers
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作者 CHENG Tingting GAO Wensheng ZHAO Yuming 《高压电器》 CAS CSCD 北大核心 2019年第3期1-7,14共8页
To promote the accuracy and application of arcing time measurement for SF6 circuit breaker in substation,five measurement methods are investigated by two cases experimentally. First,the test results of the five method... To promote the accuracy and application of arcing time measurement for SF6 circuit breaker in substation,five measurement methods are investigated by two cases experimentally. First,the test results of the five methods for a circuit breaker in different stages of wear and a circuit breaker with a component failure were presented. Then,the time error is analyzed by simulation.Finally,the advantage and disadvantage of these methods are discussed. 展开更多
关键词 CIRCUIT BREAKER high VOLTAGE CIRCUIT BREAKER ARCING time arc DURATION online monitoring WAVELET analysis
微源并网逆变器改进下垂控制策略研究 预览
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作者 韩彦东 李亚民 崔鑫斌 《河南科技》 2019年第7期41-43,共3页
针对微网中敏感负荷对频率和电压幅值要求较高这一情况,笔者提出了一种下垂系数随反正切函数变化的下垂控制策略。把反正切函数的两种特性应用于微源的下垂控制,第一个特性可以保证微源输出频率和电压始终维持在设定的范围之内,第二个... 针对微网中敏感负荷对频率和电压幅值要求较高这一情况,笔者提出了一种下垂系数随反正切函数变化的下垂控制策略。把反正切函数的两种特性应用于微源的下垂控制,第一个特性可以保证微源输出频率和电压始终维持在设定的范围之内,第二个特性可以保证微源在输出参考功率附近有较快的动态响应。最后将改进后的下垂控制策略与改进前的下垂控制策略相比较,比较结果证明了该策略的可行性和优越性。 展开更多
关键词 下垂控制 反正切函数 电压 频率
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分布式光伏发电系统对配电网电压的影响分析 预览
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作者 屈克庆 葛海锋 孔玮 《上海电力学院学报》 CAS 2019年第3期201-204,共4页
分布式光伏发电系统的接入将改变配电网的拓扑结构,给配电网带来一系列的影响。分析了分布式光伏发电系统的接入对配电网的电压、网络损耗以及保护的影响。通过在PSCAD/EMDTC软件中搭建的典型模型,研究与验证了单个分布式光伏发电系统... 分布式光伏发电系统的接入将改变配电网的拓扑结构,给配电网带来一系列的影响。分析了分布式光伏发电系统的接入对配电网的电压、网络损耗以及保护的影响。通过在PSCAD/EMDTC软件中搭建的典型模型,研究与验证了单个分布式光伏发电系统接入链式配电网对电压的影响机理。 展开更多
关键词 分布式光伏发电系统 配电网 电压 网络损耗
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A high over-potential binder-free electrode constructed of Prussian blue and MnO2 for high performance aqueous supercapacitors
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作者 Gaowei Zhang Hua Yao +4 位作者 Feng Zhang Zitao Gao Qiujun Li Yangyi Yang Xihong Lu 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第5期1061-1069,共9页
Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular... Extending the potential window of aqueous supercapacitors (SCs) up to 2.0 V is still a great challenge.Based on their good dynamic structural reversibility and open framework structure,the coordination superamolecular networks (CSNs) exhibit rapid charge/discharge ability and excellent cycle stability.As a typical coordination superamolecular network (CSN),Prussian blue (denoted as CSN-PB),which self-assembled by the CN-ligand and iron ions is firstly in-situ grown on carbon cloth,followed by electro-deposition of MnO2 to form CSN-PB/MnO2 composite electrode.Benefiting from synergistic effect of the constituent components,as well as the open framework structure of CSN-PB,this composite electrode reaches a high potential window of 1.4 V (vs.Ag/AgCl) and delivers a good specific capacitance of 315.3 F·g^-1 in aqueous electrolyte.An aqueous asymmetric device,constructed with CSN-PB/MnO2 composite as cathode and activated carbon as anode,can work in a stable potential window of 2.4 V,exhibits a high energy density of 46.13 Wh·kg^-1 and excellent cycling stability with 85.5% capacitance retention after 20,000 cycles.This work provides a new concept of high dynamic structural reversibility from CSNs to increase the cell voltage of asymmetric SCs for further boosting energy density. 展开更多
关键词 coordination superamolecular networks Prussian blue HIGH operating voltage binder-free ELECTRODE AQUEOUS SUPERCAPACITORS
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