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Effect of Different Arresters on Switching Overvoltages in UHV Transmission Lines

Tsinghua Science and Technology 2010年第3期15卷 325-328页

作者：杨鹏程陈水明何金良 State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

The amplitude of switching overvoltages is a key factor for designing the insulation of UHV equipment. The effect of different arresters needs to be studied, since installing arresters is an important way to suppress switching overvoltages in UHV transmission lines. Switching overvoltages on the 1000 kV Huainan-Huxi double-circuit transmission line were simulated for different operating modes and different arrester designs using the electromagnetic transient program PSCAD/EMTDC. With parallel resistors, the switching overvoltages are less than 1.70 p.u. （1.0 p.u.=1100×√ 2 /√3 kV）. If the arrestors are better, the switching overvoltages can be reduced even lower to 1.55 p.u. Without parallel resistors, the arresters can reduce three-phase energizing overvoltages to 1.70 p.u, while the single-phase reclosing overvoltages still exceed the limit. The results show that the parallel resistors cannot be eliminated if the arresters are only installed at each end of the transmission line. Also, better quality arresters significantly lower the switching overvoltages.

关键词： UHV double-circuit transmission line switching overvoltages arresters

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Demand analysis of the information sharing among multi-bays through the process networks in intelligent distribution substation

Demand analysis of the information sharing among multi-bays ...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： YueLin Yang Bin Wang BoYing Wen XinZhou Dong TingTing Wu Kun Liu College Of Information and Electrical Engineering CHINA Agricultural University Beijing 100083 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China School of Electrical Engineering & Renewable Energy China Three Gorges University Yichang 443000 China

Multi-bay information sharing has very important significances for the the enhancing of the relay characteristics and improving of the system control methods. With the summary of distribution substation busbar protection, small current grounding fault line selection, non-communication double-circuit line protection, reactive power and voltage control, low frequency load shedding control programmes, It analyse the needs of the information sharing among multiple bays and the application of integrated protection.

关键词： Circuit faults Substations Process control control systems Reliability Automation

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Evaluation of cascading failure in power system based on the operational reliability theory

Evaluation of cascading failure in power system based on the...

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2010 IEEE 11th International Conference on Probabilistic Methods Applied to power systems, PMAPS 2010

作者： Zou, Xin Cheng, Lin Sun, Yuanzhang Department of Electrical Engineering State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781424457236

According to the characteristics of the cascading failures in power grid, a lot of assessment methods based on the probability theory have been proposed in recent years. However, most of them ignore the influence of the changing operating conditions on the power system planning and operation. This paper assesses the risk of the cascading failure in the power system based on the operational reliability theory which considering the variation of operating states and environment of the power system. The operational reliability of the power system is calculated based on Markov Process which describes the transient probability of states. The key conception of this theory is that the failure rate and the probability of components are changing along with the life of the equipment, the operating states and the environment conditions. A new evaluation procedure is brought up to calculate the operational reliability indices which can provide the specific information of the cascading failure. The evaluating results of the test system confirm that this approach is applicable to analyze the cascading failures in real power system. ©2010 IEEE.

关键词： Reliability theory

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Cascaded battery energy storage system based on dual active bridges and a common dc bus

Cascaded battery energy storage system based on dual active ...

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2010 9th International power and Energy Conference, IPEC 2010

作者： Jin, Yiding Song, Qiang Liu, Wenhua Sun, Weixin State Key Lab. of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781424473991

Along with the increasing system capacity, large-scaled energy storage systems are supposed to be connected into 10kV or higher networks. Urban network has strict criterions on power quality of the power electronic devices connected. Moreover, the occupancy and noise of industrial frequency transformers also become restraints to the promotion of urban network energy storage. For that reason, this paper proposes a battery energy storage system based on cascaded dc-ac converter, dual active bridges, and a common dc bus. High frequency transformers are used to replace the industrial frequency transformer for insulation, and battery groups are connected to the common dc bus with respective dc-dc interfaces. This multilevel converter system is easy to modularize, easy to extend, and allows different kinds of batteries to work together. The main circuit and proper control system are designed, with the soft-switching condition and current control issues of the dual active bridge analyzed in detail. The simulation results from EMTDC model verify the operation principles and corresponding control strategies. ©2010 IEEE.

关键词： Electric inverters

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Analysis on shielding failure of large lightning current of transmision lines 30

Analysis on shielding failure of large lightning current of ...

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30th International Conference on Lightning Protection, ICLP 2010

作者： Wang, Shaoan Wang, Zhiyong Zeng, Rong Yu, Zhanqing Geng, Yinan Li, Zhizhao State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Guangzhou Power Supply Bureau China Southern Power Grid Co. LTD Guangzhou510620 China

ISBN: (纸本)9788890551901

Shielding failure of lightning is the key problem for safe operation of transmission lines. Using Electro-geometry Method to simulate the process of shielding failure, large currents hit a conducting wire hardly, however actually they did sometimes. So, Leader Progression Method is used to analyze the relationship between amplitude of lightning current and other parameters, such as wires position, ground tilt angle and so on. © 2010 University of Cagliari.

关键词： Shielding

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Protection of microgrid

Protection of microgrid

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10th IET International Conference on Developments in power System Protection, DPSP 2010

作者： Shi, Shenxing Jiang, Bo Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Syst. and Generation Equipments Tsinghua University Beijing China Areva TandD Stafford United Kingdom

ISBN: (纸本)9781849192125

The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without the need of communication, uses current traveling waves to identify faulted feeder, and the bus bar voltages to determine a event caused by fault or switch operation. In the protection scheme, current traveling waves are measured by current transducers in N line and phase lines, and wavelet multi-resolution analysis is used to decompose traveling wave signals. The initial traveling waves are compared in magnitude and polarity with each other to determine the faulted feeder. The protection is independent of microgrid operation connected with the main power grid or in island.

关键词： Electric power system protection

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Ferro-resonance over-voltage and power frequency over-voltage on the neutrals of 220kV power transformer and corresponding protection strategy

Ferro-resonance over-voltage and power frequency over-voltag...

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作者： Yu, Hua-Peng Chen, Shui-Ming Yu, Hong-Qiao Yang, Peng-Cheng Yin, Hua Wu, Gaolin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Chongqing Electric Power Research Institute Chongqing 401123 China

ISBN: (纸本)9781457700668

In order to limit short-circuit current and satisfy the need of relay setting, only part of the 220kV power transformer is grounded, so on the neutrals of ungrounded transformers will appear the over-voltage. Currently the value of over-voltage on transformer neutral point and the corresponding protection strategy is based on theoretical formula, this article use the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220kV power grid, the result shows that the power frequency transient over-voltage on the neutrals may reach 178kV, If the single-phase grounding fault occurs in ungrounded power system, the power frequency over-voltage on the neutrals will be more serious and rise to 138.6kV. Non-full phase operation may cause serious ferro-resonance over-voltage on the neutrals of no-load transformer, which may last for seconds and may rise to 723.7kV, causing serious threat to the transformer neutrals and line-side equipment. The article also studies the gap parameter which should be taken on the neutrals of 220kV transformers at the end. © 2010 Chinese Soc for Elec Eng.

关键词： power transformers

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Nanosecond-pulse dielectric barrier discharge using magnetic compression solid-state pulsed power

Nanosecond-pulse dielectric barrier discharge using magnetic...

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IEEE International power Modulator and High Voltage Conference

作者： Shao, Tao Yu, Yang Zhang, Cheng Niu, Zheng Zhang, Dongdong Wang, Jue Sun, Yaohong Yan, Ping Zhou, Yuanxiang Institute of Electrical Engineering Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Electrical Engineering Department Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424471294

Dielectric barrier discharge excitated by unipolar pulsed power is a promising approach for producing non-thermal plasma at atmospheric pressure. A magnetic compression solid-state pulse power generator is used to produce dielectric barrier discharge (DBD). The generator is capable of providing repetitive pulses with the voltage of up to 30 kV and duration of 70 ns at a 300 resistive load. This paper illustrates electrical characteristic and luminous emissions of DBD excitated by repetitive unipolar nanosecond-pulses in atmospheric air. Different from common DBD excitated by high-voltage AC sources, discharge current of DBD in the experimental investigation can be on an order of tens of amperes. When the DBD is created using two liquid electrodes, the luminous emissions from the obverse and flank sides of liquid electrodes show that no filament is observed and the discharge is homogeneous and diffuse in the whole discharge regime. © 2010 IEEE.

关键词： Dielectric barrier discharge

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Dynamic emergency control in digital distribution substation with MW PV power

Dynamic emergency control in digital distribution substation...

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2010 5th International Conference on Critical Infrastructure, CRIS 2010

作者： Wang, Bin Huang, Tianxiao Dong, Xinzhou Jiang, Bo Bo, Z.Q. Dept. of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China AREVA T and D UK Ltd. Stafford STl7 4LX United Kingdom

ISBN: (纸本)9781424480814

MW level photovoltaic generation has enough power to support the partial loads in the island operations. But the challenge is how to balance the power supply and load while the power grid is blackout, and the power supply changes to PV power. In response to this question, the anti-islanding strategy is replaced by balancing the PV output and the load shedding in paper to achieve the available maximum power balance in distribution substation. It is achieved by collecting all feeders currents (power supply and feeder outputs), which is realized in the digital substation based on IEC61850. The system scheme and the dynamic emergency control strategy to inverters in PV controller are introduced in paper. The work of the paper is valued to the research on the novel dynamic control scheme in distribution system with DGs. © 2010 IEEE.

关键词： Electric power transmission networks

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simulation of lightning strike in 2-D and 3-D with fractal theory and its application

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2010年第22期30卷 127-134页

作者： Xu, Wei Chen, Shui-Ming He, Jin-Liang State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Lighting causes great damage to power systems due to the stochastic nature of lightning discharges and the vulnerability of lightning leaders to various environments in the process of inception and propagation. In this work, the growth of diffusion limited aggregation (DLA) was adopted for reproducing branches and tortuosity of lightning channels in both 2-D and 3-D simulations. By comparing the fractal dimensions of natural lightning discharges and simulation results on various discharge settings, we discovered that a fractal coefficient η = 2 can deliver a credible model of lightning strikes. We further proved the consistency between simulation results and observations conducted in Japan during 2005 and 2006 winter seasons on lightning strikes to a windmill and its lightning-protection tower. But the credibility of the result needs to be verified by further experimental data, when the model extended from 2-D to 3-D. Moreover, striking probability and the shielding effect in the actual condition were analyzed with the proposed simulation model. © 2010 Chin. Soc. for Elec. Eng.

关键词： Fractal dimension

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