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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yunxiao Zhang Yuanxiang Zhou Ling Zhang Chenyuan Teng Zhongliu Zhou Meng Huang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

Electrical tree is one of the major issues for insulation failure in high-voltage direct current (HVDC) cable. In this paper, electrical tree initiation and growth characteristics of silicone rubber (SIR) are studied by optical tree observation system under DC and AC voltage with varied temperature. Moreover, tree channels are pictured and analyzed by 3D fluorescence imaging technology. Results show that the average tree initiation voltage, whether DC or AC, decreases exponentially with increasing temperature. However, the initiation voltage under positive DC voltages is much higher than that under AC voltages. AC tree growth pattern could be roughly divided into two modes: bush-like growing pattern and pine-like growing pattern, while DC trees stop growing after voltage stabilizes. 3D fluorescence tests show that DC tree branches are sparser and the channels are thinner. Based on the trap theory, mechanism of DC electrical tree in SIR is clarified. It is believed that different charge transport dynamics are the main reason for the differences in electrical tree behavior under DC and AC voltages.

关键词： Three-dimensional displays Temperature Shape HVDC transmission Conferences Fluorescence Space charge

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Coordinated Wholesale and Retail Market Mechanism for Providing Demand-side Flexibility

Coordinated Wholesale and Retail Market Mechanism for Provid...

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2019 IEEE Sustainable power and Energy Conference, iSPEC 2019

作者： Luo, Gang He, Yujun Zhao, Chen Zhang, Xuan Lin, Shaohua Zhao, Yue Guangdong Power Grid Co. Ltd Dispatch and Control Center Guangzhou China Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (纸本)9781728149301

With the trend of electricity market deregulation for recent decades, the consumers at demand-side are progressively encouraged to trade the power in competitive market environment. Conventionally, only large-scale consumers participate directly in the wholesale market that adopts spot energy pricing. Most small-scale consumers are involved in the retail market that offers non-varying tariff predefined by retailers or utility companies. In this work, we investigate a framework of coordinated wholesale and retail market structure that enables consumers in the retail market to reflect the spot price and improve the power system flexibility for the high penetration of renewables. Then, market behaviors of demand-side participants with the proposed market mechanism and some related business models are discussed. The following participation modes for consumers could be opted including: direct trade, trade agented by retailers or organized in virtual power plant (VPP). For a pool-based trade at demand-side, a bi-level market clearing mechanism at transmission and distribution levels is explained. This mechanism seeks to optimize the global demand profile for hosting renewables while solving the operating constraint of loads and local networks. This study can offer constructive advises to promote further development of China's electricity market. © 2019 IEEE.

关键词： power markets

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A convex hull based intertemporal loadability set approximation method

A convex hull based intertemporal loadability set approximat...

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2020 Tsinghua - HUST-IET Electrical Engineering Academic Forum

作者： Xinfei Yan Haiwang Zhong Zhenfei Tan Junfeng Yang Dept. Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China Power Dispatch & Control Center State Grid Corp. of China Beijing China

ISBN: (纸本)9781839533914

The uncertainty of renewable energy sources has aroused the interests in depicting the ability of power systems to accommodate the variations. Loadability set is one of the typical methods to characterize the feasible sets of power systems with uncertainties. The existing literature on loadability set do not incorporate intertemporal constraints, while for some cases like security check, intertemporal constraints are necessary and important. This paper firstly adapts loadability set to security check, enabling it to depict the capability of power systems to accommodate load variations. Singular value decomposition (SVD) and progressive vertex enumeration (PVE) are introduced to lighten the computational burden caused by multiple periods. The computational time can be traded off with the precision of approximation to the loadability set. Case studies verify that the loadability set can be approximated with proper precision.

关键词： Loadability feasible set convex hull security check loading capacity safety check convex hull power systems Approximation method

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Green roadmap choice for coupled system of power and urban heating: quick win or long-term strategy?

Green roadmap choice for coupled system of power and urban h...

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IEEE General Meeting power& Energy Society

作者： Yisha Lin Ying Qiao Zongxiang Lu Jin Li State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Wind Power Technology Center State Grid Gansu Electric Power Company Lanzhou China

ISBN: (数字)9781728155081

ISBN: (纸本)9781728155098

Cleanliness of energy system requires both NO x reduction due to urgent air pollution control and CO 2 cutting due to long-term climate change pressure. In the urban heating sector, quick-win plans use to be popular that focus on the NO x reduction by replacing untreated scattered coal fired boilers to natural gas or combined heat and power generators (CHPs). Meanwhile, in the electrical sector, all these fossil fuel generators should be cut down in the long-term decarbonization process. There should be a need for coordination of short- and long-term targets, because two energy supply sectors are believed to work in a coupled way in the future. A three-layered collaborative planning model is proposed in this paper: the top layer focuses roadmap economic evaluation; the middle layer applies coupled production simulation aiming at verifying energy balance; and the bottom one checks real-time operational feasibility. Pathways are made from 2020 to 2040 based on Hebei, China. Results indicate that the pathway with quick win will have delayed construction of renewable power, resulting the slow process in emission control. The long-term strategy scheme greatly promotes the renewables for supply in both sectors, but the close operational link forces the decoupling, leading to rebound on emission and operation cost on decentralized heating for the long-term future. In conclusion, the tradeoff pathway, reducing CO 2 emission as much as possible with NO x emission controlled to acceptable level, is recommended with good performance on emission control and economy.

关键词： Cogeneration Process control Production Air pollution Generators Real-time systems Planning

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Optimization of Heterogeneous Resources Combination using Virtual power Plant based on Modern Portfolio Theory

Optimization of Heterogeneous Resources Combination using Vi...

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Sustainable power and Energy Conference (iSPEC)

作者： Qiuchen Yun Liting Tian Fang Zhang Lin Cheng School of Electrical Engineering Beijing Jiaotong University Beijing China Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

In recent years, with the development of smart grid technologies, wind turbines, photovoltaics and other renewable energy sources as well as demand-side loads have participated in grid dispatching, resulting in increased complexity of energy flows in the grid. Distributed energy resources (DERs) differ in many dimensions, such as technical attributes, operating modes, and business objectives, and its management authority also belongs to different entities, making it more difficult for grids to manage DERs. A management mode, virtual power plant (VPP), being enabled by information and communication technology, could effectively overcome the challenges with decentralized DERs and help realize the aggregation of DERs. In this paper, the interaction between customers and VPP is modeled, where VPP divides the owners of DERs into three categories according to the willingness and responsiveness of customers and balances budget costs and risks based on the modern portfolio theory. simulation with the CIGRE 20kV distribution network benchmark demonstrates that VPP could greatly meet the power consumption demand of multiple participants during operation. This paper also provides a basis for the selection of DERs aggregated by VPP. 1 1This paper is sponsored by the National key Research and Development Program (No.2017YFB0903300) and National Natural Science Foundation of China (No.51807107) 2 2This paper is sponsored by the Young Talents Support Project of the Chinese Society for Electrical Engineering (CSEE) titled “Research on key technologies for optimal operation and control of transportation energy systems”.

关键词： power demand Transportation Benchmark testing Wind turbines Smart grids Portfolios Optimization

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Analysis of Adaptive Re-closure in AC-DC Hybrid power System 8

Analysis of Adaptive Re-closure in AC-DC Hybrid Power System

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Xie, Min Zhang, Wei Liu, Ludeng Jia, Xin Wang, Bin Dong, Xinzhou Dispatching and Controlling Center of Anhui Electric Power Company State Grid Hefei China Tsinghua University Key Lab of Control and Simulation of Power Systems and Generation Equipment China

ISBN: (纸本)9781728117225

The beat frequency characteristic of the recovery voltage of fault phase in the case of single-phase grounding transient fault happening to line with the shunt reactors is analyzed. Besides, the paper analyzes the reason of no beat frequency phenomenon of transient fault happening to line without shunt reactor. The AC power networks with metallic grounding fault and arc grounding fault are analyzed by simulation. The recovery voltage of single-phase grounding fault in AC/DC hybrid power grid is studied by PSCAD. The new problems of the adaptive re-closure in AC-DC hybrid power system are discussed. Then the follow-up ideas to solve several existing problems are also presented. © 2019 IEEE.

关键词： Electric power transmission networks

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Polymeric insulating materials characteristics for high-voltage applications

Nature Reviews Electrical Engineering

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Nature Reviews Electrical Engineering 2024年 516-528页

作者： Tian-Yu Wang Gui-Xin Zhang Zhi-Min Dang Jie Mao Boya Zhang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Department of Chemical and Biomolecular Engineering University of California Los Angeles CA USA School of Chemistry and Chemical Engineering State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering Ningxia University Yinchuan China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University Xi’an China

Large-scale power system transmission and transformation equipment operates in high-voltage environments, placing notable requirements on the insulation strength of polymers used in core insulation frameworks. Increasing the polymer insulation performance in high-voltage environments is crucial for protecting large-capacity and integrated power equipment and ensuring the safe and stable operation of electrical devices. Here, we discuss the phenomena and the underlying mechanisms of bulk breakdown and surface flashover that lead to insulation failure in polymers and present relative strategies to increasing the performance of the insulating materials. We analyse the challenges faced by polymeric insulating materials in various extreme environments and the strategies to address them. Finally, we identify key challenges and highlight future directions and opportunities for the development of reliable polymeric insulating materials.

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A Novel Method of power Swing Blocking in Impedance Relay 8

A Novel Method of Power Swing Blocking in Impedance Relay

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Wang, Hao Kang, Xiaoning Dong, Xinzhou Xi'an Jiaotong University Shaanxi Key Laboratory of Smart Grid Xi'an China Tsinghua University State Key Laboratory of Control and Simulation Power System and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Distance protection is widely applied in High/Ultra- High Voltage AC transmission system. Impedance relay, the core element of distance protection, may operate incorrectly under power swing, so a power swing blocking unit is needed in distance protection. In this paper, the phase difference between the measurement voltage and compensation voltage under power swing and line fault is analyzed. Based on the analysis, a power swing blocking strategy using the change rate of phase difference between measurement voltage and compensation voltage is proposed. simulation results in PSCAD/EMTDC indicate that the proposed strategy can block the impedance relay reliably under power swing and unblock the impedance relay after detecting the fault under power swing. © 2019 IEEE.

关键词： Electric power system protection

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Space Charge Characteristics of Oil-paper under AC/DC Composite Voltage

Space Charge Characteristics of Oil-paper under AC/DC Compos...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yuanxiang Zhou Xin Huang Ling Zhang Yunxiao Zhang Zhongliu Zhou Chenyuan Teng Lei Xue Meng Huang The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Haidian Beijing China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power Universiy Beijing China

ISBN: (纸本)9781728195728;9781728195735

Oil-paper insulation bears AC/DC composite voltage in converter transformers. However, the AC/DC space charge behavior is still not clear, which will result in electric field distortion, material aging and even insulation failure. In this work, the space charge distribution of oil-paper under the AC/DC composite voltage with the AC/DC ratio of 1:1, 1:3, 1:5, and 1:7, is studied by pulse electroacoustic (PEA) method, respectively. It was found that as DC component increases, the accumulated charge near the electrode decreases, while the interior charge increases. It suggests that DC stress mainly influences the amount and the depth of space charge accumulation. AC component has a relatively significant impact on the injection and extraction behavior of space charge near the electrode. Furthermore, AC/DC composite voltage enhances the migration of space charge compared with that under DC voltage. This research contributes to the further understanding of the space charge characteristics of oil-paper under AC/DC composite voltage, which will benefit the safe and stable operation of converter transformers.

关键词： Electrodes Conferences Space charge Oil insulation Aging Distortion Dielectrics

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Steady-state model of multi-port electric energy router and power flow analysis method of AC/DC hybrid system considering control strategies

Steady-state model of multi-port electric energy router and ...

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作者： Shen, Yu Zhu, Fengju Zhang, Chunpeng Cai, Weiqian Yuan, Liqiang Li, Kai Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

This study proposes a steady-state model of multi-port electric energy router (EER) and a power flow analysis method for AC/DC hybrid system considering control strategies. Firstly, a circuit topology model of EER is put forward, including AC and DC port equivalent parts. Secondly, considering external control characteristics of EER, the control strategies including PQ mode, V/f mode, and droop mode are established, which is suitable for system analysis. Then, using the extended sub-network model, an AC/DC power flow model containing multi-port EER is established. In terms of the power flow algorithm for AC/DC hybrid system, AC/DC network admittance matrix and the extended AC/DC network modification equations are applied to solve the problem. Two examples are designed and show that EER can be used for flexible power regulation and voltage improvement. Besides, power flow analysis method of AC/DC hybrid system is demonstrated to be effective. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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