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Basic reason for the accumulation of charge on the surface of polymer dielectrics

Science China Materials 2022年第10期65卷 2884-2888页

作者： Tianyu Wang Xiaofen Li Boya Zhang Dayu Li Jianbo Liu Guixin Zhang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityShaanxi 710049China

Due to their outstanding electrical insulation performance,low energy loss and high reliability,polymer dielectrics are widely used in flexible electronics,capacitors and large-scale power transmission equipment[1–5].However,polymer dielectrics accumulate large amounts of charge on their surface during use,which causes local electric field distortion and induces flashover,explosion,and equipment damage[6–9].Although researchers have attempted to develop methods to reduce the accumulation of surface charge through material modification,such as plasma treatment[10],direct fluorination[11],and coating[7,9,12],each of these methods has drawbacks;thus,the bottleneck has yet to be overcome.

关键词：电荷量第一性原理计算聚合物表面电介质电场畸变深能级缺陷电荷测量电荷特性

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Distribution system fault location method using reclosure-generating traveling waves

Distribution system fault location method using reclosure-ge...

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2020 IEEE power and Energy Society General Meeting, PESGM 2020

作者： Dong, Xinzhou Wang, Haozong Xin, Zeyu Shi, Shenxing Wang, Bin Tsinghua University State Key Lab. of Control and Simulation of Power System and Generation Equipment Dept. of Electrical Engineering Beijing China

ISBN: (纸本)9781728155081

Fault location in distribution systems includes 2 subtasks: fault distance estimation and fault section identification. This paper presents a fault location method based on reclosure-generating traveling waves and system topology. Firstly, the reclosure-generating traveling waves under normal and fault conditions are analyzed to find the traveling wave reflected by fault point, through which the fault distance could be estimated. Secondly, we propose a fault section identification method by comparing real measured traveling waves with simulated traveling waves with different potential fault points. Noticing that only time information of traveling waves rather than their magnitude is necessary, instead of using electromagnetic transient simulation, we also present a simplified simulation algorithm that only focuses on the arrival time of traveling waves based on priority queue. Experiments demonstrate that the proposed method can locate fault points in high accuracy with low computational burden. © 2020 IEEE.

关键词： Location

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Research on Low Voltage Ride through and Reactive power Support of Hydrogen Production power Supply

Research on Low Voltage Ride through and Reactive Power Supp...

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Smart power & Internet Energy systems (SPIES), International Conference on

作者： Mingqi Zhang Ruitong Liu Kui Wang Kai Sun Qinglai Guo Yongdong Li Dept. of Electrical Energineering State Key Lab. of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Grid Liaoning Electric Power Co. LTD. Electric Power Research Institute Shenyang China

Hydrogen energy, a type of green secondary energy, has attracted much attention in recent years. The production of hydrogen by water electrolysis is less harmful to the environment and makes it possible to obtain hydrogen with a high degree of purity. But it requires a lot of electricity and is expensive. Installed capacity and the share of electricity generation from new energy sources have increased recently. The "double high" trend in the power system is becoming apparent. The combination of new energy power generation and hydrogen production by water electrolysis can not only promote the absorption of new energy power generation, but also reduce the cost of hydrogen production. The conventional thyristor power supply system for hydrogen production has low power factor and poor harmonic performance, which cannot meet the requirements of the new power system. Hydrogen production power supply based on fully controlled devices is gradually becoming mainstream. In this paper, the low voltage ride through capability and the reactive power support function for the power grid of hydrogen production power supply based on fully controlled devices are verified by simulation. For both symmetrical and asymmetrical faults, the hydrogen production power supply can ride through the fault.

关键词： Performance evaluation Reactive power power supplies Hydrogen Production Voltage power grids

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Capacitor Voltage Balancing Strategy Based on Zero-Sequence Voltage Injection for Half-Wave Commutated Modular Multilevel Converter

Capacitor Voltage Balancing Strategy Based on Zero-Sequence ...

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International Conference on power Electronics and Motion control (IPEMC)

作者： Nan Fu Bao Liu Yunfei Xu Sitong Zhu Kui Wang Yongdong Li Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd Changping Beijing China Electric Power Research Institute of State Grid Liaoning Electric Power Co. Ltd. Shenyang China

ISBN: (数字)9798350351330

ISBN: (纸本)9798350351347

Half-wave commutated modular multilevel converter (HWC-MMC) is suitable for high-voltage large-capacity AC-AC conversion, and an appropriate capacitor voltage balancing strategy is essential. This paper analyzes the condition of capacitor voltage balancing and proposes a capacitor voltage balancing strategy based on optimal zero-sequence voltage injection using the model predictive control. Finally, the simulation is carried out to verify the proposed strategy.

关键词： Multilevel converters Voltage fluctuations Capacitors High-voltage techniques power system harmonics power electronics Steady-state

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Stability Analysis and Braking system Design of Icebreaker Propulsion system Based on 3L-NPC Inverter

Stability Analysis and Braking System Design of Icebreaker P...

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Smart power & Internet Energy systems (SPIES), International Conference on

作者： Nianzhou Liu Nan Fu Pengfei Xie Wenfeng Long Kui Wang Yongdong Li Science and Technology on Ship Integrated Power System Technology Laboratory Wuhan Institute of Marine Electrical Propulsion Wuhan China State Key Lab of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

The icebreaker is important in the polar scientific investigation and resource exploration. There will be pulse and periodic load during the continuous icebreaking process, which may affect the propulsion system of the icebreaker. This paper mainly analyzes the effect of the impact load on the three-level neutral point clamped (3L-NPC) inverter with diode front-end, and demonstrates the relationship between the impact load and the feedback energy. Moreover, the choice of the resistance of the braking resistor is briefly discussed. The simulation results are given at last, which verify the rationality and correctness of the theoretical analysis.

关键词： Resistors Resistance simulation Energy Propulsion Inverters Stability analysis

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Investigation of The Anti-icing Performance of Superhydrophobic Silicone Rubber

Investigation of The Anti-icing Performance of Superhydropho...

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2022 IEEE International Conference on High Voltage Engineering and Applications, ICHVE 2022

作者： Liu, Shuming Liu, Shuqi Wang, Qian Zuo, Zhou Wang, Tingting Luo, Bing Liang, Xidong Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Beijing100084 China Csg Electric Power Research Institute Co. Ltd. Guangzhou510663 China The Natl. Eng. Res. Ctr. for Ultra High Voltage Eng. Technol. and Innov. Elec. Equipment Foundation China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407502

Composite insulators, as an important part of outdoor transmission lines, always suffer from various environmental stress, and the large-scale icing accretion problem is one of the dangerous threats. In this paper, superhydrophobic silicone rubber was prepared by surface coating method, and its anti-icing performance compared with pristine silicone rubber was investigated. The superhydrophobic surface can repel water droplets so that the droplets can be removed easily before freezing. For the sessile droplets, the freezing speed on the pristine silicone rubber is faster than the process on coated silicone rubber. After completing freezing, the deicing force on pristine silicone rubber is bigger than that on coated silicone rubber. In summary, the superhydrophobic silicone rubber showed more excellent performance in inhibiting ice accretion than the pristine silicone rubber, and it is a potential solution to the icing problem in the power system. © 2022 IEEE.

关键词： Electric power transmission

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Adaptive deblock for DC line fault in full bridge sub-module based MMC-HVDC system 15

Adaptive deblock for DC line fault in full bridge sub-module...

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15th International Conference on Developments in power system Protection, DPSP 2020

作者： Cai, Jing Dong, Xinzhou State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781713827894

Modular multilevel converter based high voltage direct current (MMC-HVDC) transmission technology has been widely applied in power systems, such as AC systems interconnection and renewable energy access, due to its superiorities. The long distance and complex operation environment lead to high probability of DC transmission line faults. Inevitable faults will interrupt normal power transmission and may cause severe accidents without appropriate faults handling scheme in both HVDC and AC/DC hybrid systems. MMC-HVDC utilizing submodules with fault clearing ability, such as Full-Bridge-Submodule (FBSM), can reduce fault current rapidly through blocking all submodules and attempt to resume power transmission by deblocking after waiting for deionization time. But the deblock operation is blind, which may aggravate outrage consequences with producing extra impacts on system and extending fault handling time in case of permanent faults. In order to realize ideal fault handling, which means submodules only deblock under temporary fault while cut off the fault line in case of permanent fault, an adaptive deblock strategy is proposed in FBSM based MMC-HVDC system mainly through distinguishing two fault states. A simulation model is established in PSCAD/EMTDC to verify feasibility and effectiveness of proposed scheme. Applicability to other submodules with fault clearing capability also been analysed. © 2020 IET Conference Publications.

关键词： Renewable energy resources

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A power Conversion system For Large-Scale Reversible SOFC Energy Storage system

A Power Conversion System For Large-Scale Reversible SOFC En...

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IEEE Electronic power Grid (eGrid)

作者： Hongsheng Chong Kai Sun Huan Chen State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781665449809

As the penetration rate of renewable energy in the utility grid increases, large-scale energy storage system (ESS) will become an essential infrastructure in the grid. Reversible solid oxide fuel cell (RSOFC) technology is a promising solution for large-scale ESS. However, the wide voltage range and low power of single RSOFC stack electrical characteristics have complicated the interface converter design. It is necessary to connect multiple stacks through a power conversion system to integrate the power because a single stack of RSOFC is small. This paper proposes a power conversion system for large-scale RSOFC ESS. The system consists of a cascaded H-bridge (CHB) converter and multiple multiport converters, and they are connected to a common dc bus. Because of the electrical characteristics of RSOFC, a two-stage CLLC based multiport converter topology is employed to achieve high voltage gain and operate at a wide voltage range. The control strategy of the proposed power conversion system is presented. simulation tests verify the feasibility and effectiveness of the proposed conversion system

关键词： Renewable energy sources Conferences Fuel cells High-voltage techniques Electric variables Solids Topology

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The Correlation Mechanism that Micro-Structure Parameters of ZnO Varistor to the Macroscopic Electrical Characteristics

The Correlation Mechanism that Micro-Structure Parameters of...

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International Conference on Electrical Materials and power equipment (ICEMPE)

作者： Pengfei Meng Jingke Guo Long Zhao Wenhao Lu Zheng Liu Shan Li Kai Zhou Jun Hu College of Electrical Engineering Sichuan University Chengdu China State Grid Linyi power supply company STATE GRID Corporatio of China Linyi China High Voltage Technology Department Extra High Voltage Power Transmission Company of CSG Guangzhou China State Key Laboratory of Intense Pulsed Radiatio Simulation and Effect Northwest Institute of Nuclear Technology Xi’an China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

As the core part of metal oxide arresters, ZnO varistor plays an important part in suppressing the overvoltage of power systems. With the development of UHV technology, the residual voltage and energy capacity of ZnO varistors have put forward higher requirements. The research is carried out from the perspective of material calculation, studied the correlation mechanism between micro-structure parameters and various macroscopic electrical characteristics of ZnO varistor based on Voronoi network. And the microstructure parameters such as grain size and size inhomogeneity were calculated and studied. The study simplified the optimization problem with multiple variates and objectives, into the one with two categories of variates and two categories of objectives. And then proposed specific strategies. The research provides important theoretical basis for improving the performance of ZnO varistors, and witch is of great significance for the design and manufacture of high-performance lightning arresters.

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Backup Solution for Traveling Wave Differential Protection Under Synchronization Failure

Backup Solution for Traveling Wave Differential Protection U...

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

作者： Haozong Wang Qihuan Dong Wenzhong Li Binshu Chen Xinzhou Dong Pengfei Lv Zhihuai Shu Kun Liu Zebing Shi State Key Lab. of Power System and Generation Equipment Tsinghua University Beijing China State Grid Corporation of China Beijing China Dispatching and Controlling Center Guangdong Power Grid Co. Ltd Guangzhou China China Southern Power Grid Co. Ltd Guangzhou China

Traveling wave differential protection (TWDP) has shown advantages over traditional current differential protection in terms of sensitivity, rapidity and immunity to distributed capacitive current. However, existing TWDP schemes depends heavily on data synchronization through either GPS or communication, of which the potential failure should be considered. This paper discusses the backup solutions for TWDP in condition of synchronization failure. Firstly, the influence of synchronization error to TWDP is analyzed. The results indicate that such error would lead to mal-operation under external faults. Secondly, a backup algorithm is proposed to handle the synchronization failure issus. Extensive simulation experiments based on the PSCAD/EMTDC software show that the proposed method could avoid mal-operation under external faults while maintain sensitivity to internal faults even if synchronization error is large.

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