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Annual IEEE Conference on Applied power Electronics Conference and Exposition (APEC)

作者： Na Zhi Hui Zhang Xi Xiao Faculty of Automation and Information Engineering Xi'an University of technology Xi'an Shannxi China State Key Lab of Control and Simulation of Power System and Generation Equipments Tsinghua Universty Beijing China

ISBN: (纸本)9781467395519

DC microgrids are becoming popular in distribution systems based on its higher reliability and system efficiency. DC bus signal (DBS) control as a common control strategy was widely used in dc microgrids, in which, control mode of each power electronic converter is triggered by monitoring the dc voltage variation to keep the power balance of the dc microgrid. Most of the dc microgrid stability analysis are linear and based on the impedance matching theory. But the dc microgrid will be a nonlinear system when the operation mode was automatically switched based on switching information. In this paper, the switched system theory was used to analyze the stability of dc microgrids under DBS control strategy. The stability conditions in each subsystem and switched system was present in this paper and simulation results verify the effectiveness of the proposed criterion.

关键词： Microgrids Voltage control Stability analysis Satellite broadcasting Switches power system stability

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Electrical tree initiation and propagation in silicone rubber under long-term AC aging

Electrical tree initiation and propagation in silicone rubbe...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yunxiao Zhang Yuanxiang Zhou Ling Zhang Ming Chen Xu Zhang Yanchao Sha State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing Beijing CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China North China Electric Power Research Institute Co Ltd Beijing Beijing CN North China Electric Power Research Institute Co Ltd. Beijing China

Electrical tree break-down is the major failure problem in cable accessories, however, mechanisms of the electrical tree initiation and propagation are still lack of deeply research, especially in silicone rubber (SIR) which is widely used as insulation material for cable accessories. Long-term aging (0- 1000 h) experiments under the different voltages were conducted to observe electrical tree initiation and propagation processes. In trees initiation stage, with increasing of applied voltage, electrical tree initiation probability becomes larger, while tree initiation time dramatically decreases. The experiment observations demonstrated four shapes of trees which are dominated. As applied voltage increasing, the numbers of electrical trees life-cycles increased and exponential relationship was found between tree length and magnitude of applied voltage. It is noted that charges, whose energy exceeding a certain critical value, destroy microstructure of dielectric accumulatively via injection and extraction, and cause electrical trees initiate when it accumulates to a visible extent.

关键词： Electrodes Aging power cables Electric fields Needles power cable insulation

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High impedance fault detection on distribution systems with harmonic interference in wind farms

High impedance fault detection on distribution systems with ...

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13th International Conference on Development in power system Protection 2016 (DPSP)

作者： Jiang Ni Bin Wang Xinzhou Dong State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. To solve this problem, the typical HIF arc flash based on Mayr's arc model is first built, and the typical fault waveforms of HIF in wind farm are presented. Then the characteristics of high impedance faults are analysed to distinguish the occurrence of HIF from other harmonic interference. After that, the performance of the traditional harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is presented to prevent harmonic interference influence in wind farms.

关键词： distribution system Wind farm high impedance faults harmonic algorithm

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AC-constrained Optimal power Flow Considering Wind power generation Uncertainty in Radial power Networks 34

AC-constrained Optimal Power Flow Considering Wind Power Gen...

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第三十四届中国控制会议

作者： LIU Bin LIU Feng MEI Shengwei State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

ISBN: (纸本)9781467374439

Wind power generation uncertainty has imposed great challenge on power systems' operation and should be considered when making an operation *** this paper,we focus on optimal power flow(OPF) problem in radial power networks while considering wind power generation *** cope with this uncertainty,the stochastic AC-constrained OPF(ACOPF) problem considering both continuous and discrete devices is formulated based on our previous *** second order cone relaxation is employed to relax the original mixed integer nonconvex nonlinear programming(MINNLP) problem to a mixed integer second order cone programming(MISOCP) problem which can be solved by commercial solvers with high computation *** modified IEEE 33 bus distribution system is studied in this paper which validate the effectiveness of the proposed model.

关键词： optimal power flow wind power stochastic optimization radial power networks uncertainty set

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Active voltage balancing control for multi HV-IGBTs in series connection

Active voltage balancing control for multi HV-IGBTs in serie...

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IEEE Energy Conversion Congress and Exposition

作者： Shiqi Ji Fred Wang Leon Tolbert Ting Lu Zhengming Zhao Hualong Yu Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN USA State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781509007387

The series connection of insulated gate bipolar transistors (IGBTs) allows the operation at voltage levels higher than the rated voltage of one IGBT. However, the technology has not been widely applied due to transient voltage unbalance. Asynchronous gate drive signals, which cause series-connected IGBTs not to turn-on and turn-off at the same time, result in serious unbalanced voltage sharing. This paper presents an active voltage balancing control for multi series connected HV-IGBTs including the active voltage balancing control (AVBC) circuit integrated in the gate driver and the control for multi series connected IGBTs. The effectiveness of the control has been experimentally validated in a 10 kV dc-link voltage converter using four 4.5 kV HV-IGBTs in series connection.

关键词： active voltage balancing control multi HV-IGBTs series connection

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A dynamic multi-level temporal and spatial coordination method for orderly power utilization based on customer load curtailment cost characteristics

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Dianwang Jishu/power system Technology 2016年第2期40卷 425-432页

作者： Yan, Qingguo Tong, Xing Zhang, Ning Chen, Xiao Yi, Yongxian State Grid Jiangsu Electric Power Company NanjingJiangsu Province210024 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Jiangsu Electric Power Company Research Institute NanjingJiangsu Province210019 China State Grid Key Laboratory of Electric Power Metrology NanjingJiangsu Province211103 China

When there is power supply shortage or emergency event in power system, orderly power utilization needs to be applied to cut down electricity demand to maintain power supply for important electricity consumers. Current orderly power utilization fails to consider curtailment costs for different regions and customers, and ignores temporal continuity and production regularity of customer, leading to inefficient load curtailment scheduling. This paper proposes a dynamic multi-level temporal and spatial coordinated shortage allocation method considering customer load curtailment costs for orderly power utilization. Load curtailment cost function is established from individual customer level up to provincial electrical grid level. An optimization model is proposed to strategically rearrange customer load profiles across multiple periods. Case studies show that the method efficiently coordinates power shortage in temporal and spatial scale, and significantly brings down economic cost due to curtailment allocation. This model could help promote customer satisfaction level in orderly power utilization. © 2016, power system Technology Press. All right reserved.

关键词： Electric power utilization

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An evolution model with high proportion of renewable energy

An evolution model with high proportion of renewable energy

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Chinese control Conference (CCC)

作者： Weiqi Zhang Xinyan Zhang Yukai Xia Shaowei Huang Jinyu Xiao Chang Lu Shengwei Mei College of electrical engineering Xinjiang University Wulumuqi Xinjiang CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing Beijing CN State Power Economic Research Institute Beijing China

Compared with other conventional energy sources, renewable energy, which results in less pollution and has numerous resources, is a significant factor in addressing the current issues of the serious environmental pollution and the resource depletion. Large-scale renewable energy connected to the grid could lead to a the change of the morphological structure and the operation modes of energy transmission. While current power grid evolution models did not consider the characteristics of renewable energy in the evolution strategy. The expansion mechanism of the future transmission network with a high proportion of renewable energy is studied in this paper. The operation cost including renewable energy curtailment are optimized using the production simulations, where the stochastic and intermittent of wind and solar energy are modeled. And the dual variable information is adopted to drive the grid upgrading. The expansion strategies for power grid of Zhejiang province in China are analyzed to balance the construction cost and curtailment cost of renewable energy.

关键词： power grids Load modeling Renewable energy sources Wind power generation Economics Production

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Iron loss evaluation and comparison in application of reduced common mode voltage PWM methods 7

Iron loss evaluation and comparison in application of reduce...

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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Liu, Fang Lu, Ting Zhao, Zhengming Gu, Qing Yuan, Liqiang Li, Kai State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781467371506

The application of reduced common mode voltage pulse width modulation methods bring much high order harmonics to the variable speed drive system, which causes considerable iron loss inside the electric motor. In this paper, an improved iron loss model considering those high order harmonics is proposed. Iron loss coefficients are obtained based on experimental data by utilizing multiple linear regression and harmonics analysis method. Comparisons of the iron losses between various PWM methods are made for both experimental results and calculated results. It is found that by utilizing RCMV PWM methods, the iron loss of the induction motor becomes larger. The differential values of iron losses between RCMV PWM and CPWM decrease with the increase of the modulation ratio as a result of the reduction of zero space vectors' action time. © 2015 IEEE.

关键词： Pulse width modulation

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Design and validation of real-time dynamic spectrum management in OFDM-based HNPLC systems

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High Technology Letters 2015年第4期21卷 379-387页

作者：刘雯静 Guo Jingbo Yan Yanxin Zhang Tongfei State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University ROHM Semiconductor(Shanghai) Co. Ltd.Design Center

Time-varying frequency selective attenuation and colored noises are unfavorable characteristics of power line communication(PLC) channels of the low voltage *** overcome these disadvantages,a novel real-time dynamic spectrum management(DSM) algorithm in orthogonal frequency division multiplexing(OFDM)-based high-speed narrow-band power line communication(HNPLC) systems is proposed,and the corresponding FPGA circuit is designed and *** of the proposed DSM is validated with a large amount of network experiments under practical PLC *** the noise in each narrow subcarrier is approximately Gaussian,the proposed DSM adopts the BER/SER expression formulized via the AWGN channel to provide a handy and universal strategy for power *** real-time requirement is guaranteed by choosing subcarriers in group and employing the same modulation scheme within each *** measures are suitable for any modulation scheme no matter the system criterion is to maximize data rate or minimize power/*** design and hardware implementation of the proposed DSM are given with some flexible and efficient *** DSM circuit is carried out with Xilinx *** and practical experiments validate that the proposed real-time DSM significantly improves system performance.

关键词： real-time dynamic spectrum management high-speed narrowband power line com-munication （HNPLC） subcarrier grouping rate adaptive multi-carrier

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Feature extraction in machine degradation with variational mode decomposition

Feature extraction in machine degradation with variational m...

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Joint Conference on Society for Machinery Failure Prevention Technology Conference, MFPT 2015 and ISA's 61st International Instrumentation Symposium, IIS 2015 - Technology Evolution: Sensors to systems for Failure Prevention

作者： Liu, Chao Jiang, Dongxiang Yang, Wenguang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

The measured parameters change with the machine degradation, where the trends of the parameters can be applied in condition prediction. The deterioration of the parameters usually present characteristics in a monotonic or low-frequency way. As the measure signal are merged with instant signals, noise and measurement error in different frequency bands, model decomposition approaches are widely applied to separate the different bands for feature extraction. Among the model decomposition methods, Variational model decomposition is recently proposed by K. Dragomiretskiy and D. Zosso as a non-recursive model which can extract modes concurrently. This work will analyze its effectiveness in degradation feature extraction and application in condition prediction in prognosis. Firstly, variational model decomposition is analyzed, where the characteristics of variational model decomposition are compared with another mode decomposition method ensemble empirical mode decomposition. simulation data is applied to test the effectiveness of the mode decomposition methods. Secondly, field data with component degradation is collected, and the degradation feature extraction is applied with the three methods mentioned above.

关键词： Empirical mode decomposition

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