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2020 10th International Conference on power, Energy and Electrical Engineering, CPEEE 2020

作者： Li, Jiaming Qiao, Ying Liu, Guojing Lu, Zongxiang State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing100084 China Economic Institute of Technology State Grid Jiangsu Electric Power Company Nanjing210005 China

Battery energy storage system (BESS) is one of the important solutions to improve the accommodation of large-scale grid connected photovoltaic (PV) generation and increase its operation economy. However, the strong intra-day volatility and severe curtailment of PV power sets a high demand of BESS charge-rate that is a key factor in operation models but ignored in current planning researches. This paper proposes a BESS capacity configuration model for PV generation systems which takes BESS's ability to (dis)charge exceeds its rated power into account. The best charge-rate and power & energy capacity of BESS are optimized by particle swarm optimization (PSO) algorithm. Through an analysis of the annual output statistics of PV power station in the northwest of China, the results show that when considering the high charge-rate of BESS, the optimal BESS capacity configuration rises and comprehensive income of the PV-BESS system will increase. © 2020 The Authors, published by EDP Sciences.

关键词： Battery storage

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Breakdown phenomena caused by electrical tree degradation in high density polyethylene under high frequency voltage

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Gaodianya Jishu/High Voltage Engineering 2007年第12期33卷 14-18页

作者： Zhou, Yuan-Xiang Xing, Xiao-Liang Nie, Qiong Wang, Yun-Shan Wang, Ning-Hua Liang, Xi-Dong Guan, Zhi-Cheng State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

The shape change of electrical tree propagating in ice-water quenched high-density polyethylene (HDPE) film under AC voltage of different frequency ranging from 50 Hz to 90 kHz as well as the breakdown phenomena caused by the treeing degradation under high frequency condition were studied. The electrical treeing aging experiment is carried out at room temperature. The shape change of electrical tree and the arcing process during the experiment is observed via a digital micro-observing system. It is found that the arcing process can be obviously observed under a high frequency voltage compared with that under low frequency voltage. It is also found that under different frequency voltages the electrical tree initiation shape is different. Most of the electrical trees are branch-shape tree under lower frequency voltage. When the frequency is higher than 5 kHz, trunk-shape tree and bosk-like tree appears. Once the frequency is higher than 50 kHz, breakdown tree can be found out. It is shown that the tree shape conversion is influenced by the frequency. The electrical tree usually has a simple shape and rarely changes under low frequency voltage in one hour or more. However, under a high frequency voltage, the electrical tree shape changes more frequently and has a large probability to breakdown. The influence of frequency on material polarization process, fatigue and thermo effect is considered as the main causes of the experiment results. The more serious destruction caused by high frequency electrical treeing degradation can well explain the reason of insulation premature inactivation in mid-frequency or high-frequency electrical equipment.

关键词：聚乙烯树老化电树形态转换击穿频率

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Analysis of foundation grounding system buried in a horizontal multilayer soil by means of the fictitious conductivity concept

Analysis of foundation grounding system buried in a horizont...

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作者： Zou, J. Lee, J.B. Chang, S.H. Zhang, B. He, J.L. Ji, Y.F. State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China Electrical Environment and Transmission Group Korea Electrotechnology Research Institute Changwon 641600 Korea Republic of

The theoretical model for the analysis of grounding system encased in the foundation region in a horizontal multilayer soil is presented. By means of fictitious conductivity concept, the effects of foundation are replaced by a set of equivalent current sources. The analysis of grounding system can be carried out by combining the moment method with additional equivalent current sources. The main advantage of the proposed approach is that it can be linked with the existing codes easily. The results are compared with those found in the literature and obtained by other popular software. © 2007 IEEE.

关键词： Electric grounding

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Influences of temperature on Space Charge in Gas-to-Liquid Oil-Impregnated Paper

Influences of temperature on Space Charge in Gas-to-Liquid O...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Yuanxiang Zhou Xin Huang Ling Zhang Yunxiao Zhang Zhongliu Zhou Chenyuan Teng China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

Gas-to-liquid (GTL) transformer oil has been on trial in converter transformers. However, its influence on the space charge characteristic is not clear. This work aims at exploring space charge characteristics of GTL oil at different temperatures as well as comparing with commercial naphthenic oil (KI50X). Space charge distribution during the polarization and the dissipation process in the GTL oil-impregnated paper at different temperature was measured by the pulse electroacoustic method (PEA), which were contrasted with those of the KI50X oil-impregnated paper. Results illustrated that high temperature accelerated the injection and migration of charge carriers in the oil-impregnated paper. And the polarity of the accumulated charge in the vicinity of anode changed from positive to negative with the increase of temperature. It was perceived that oil-paper conductivity and carrier mobility grew with the increase of temperature, resulting in the easier migration of injected charge to another electrode. Furthermore, the space charge dissipation rate in the GTL oil-impregnated paper is lower than that in the naphthenic oil-impregnated paper at the same temperature. Thus, a longer time interval of tests or switch operation in the factory test and operation process may need if GTL oil is used rather than naphthenic oil.

关键词： Oils Space charge power transformer insulation Oil insulation Electric fields Distortion Temperature measurement

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Steady-state Operation Area of VSC-HVDC Converter Station Connecting Renewable Energy Cluster by Isolated Network 10

Steady-state Operation Area of VSC-HVDC Converter Station Co...

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2020 10th International Conference on power, Energy and Electrical Engineering, CPEEE 2020

作者： Xian, Wenyuan Ding, Ran Qiao, Ying Lu, Zongxiang Li, Shangqiang Lin, Hong School of Electrical Engineering Xinjiang University Urumqi830047 China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China State Grid Jibei Electric Power Company Xicheng District Beijing100053 China

When the large-scale renewable power island is connected to VSC-HVDC transmission system, we should figure out the steady-state operation area of VSC-HVDC converter station. Based on the equivalent model of renewable energy island, the constraints of VSC-HVDC converter station are analyzed, and a fast method for calculating steady-state operation area of converter station is presented in this paper. The influence of equivalent line impedance of renewable energy island, transformer ratio of converter station and voltage setting value of grid-connected point on steady-state operation area of converter station is analyzed. And the three-dimensional view of the steady-state operation area of the converter station under different grid-connected voltage is depicted. © 2020 The Authors, published by EDP Sciences.

关键词： HVDC power transmission

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Distribution line automation system based on non-communication protection in the case of symmetrical fault

Distribution line automation system based on non-communicati...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Yin, Diqing Liu, Kun Dong, Xinzhou Shi, Shenxing Xu, Gang Wang, Kai North City Branch of Shanghai Power Company Shanghai 200072 China Status Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Distribution line non-communication protection (DNCP) can quickly and selectively isolate unsymmetrical fault, but the performance of this distribution line automation system is not satisfying in the case of symmetrical fault. This paper proposes a scheme which can quickly isolate symmetrical fault and block the operation of BPS: DNCP which is closed to the source can operate instantaneously, that can avoid overheating damage of electrical equipment;when the magnitude of voltage falls, BPS will detect the magnitude of negtive voltage two cycles ago to make a decision, that can avoid the process of connecting to permanent fault and tripping again for the ring main unit. EMTP simulation results show the effectiveness of the scheme. © 2011 IEEE.

关键词： Automation

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Research on reliability of Ad hoc network communication in UAVs formations 6

Research on reliability of Ad hoc network communication in U...

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6th IEEE International Symposium on Electromagnetic Compatibility, ISEMC 2019

作者： Li, Yanchu Li, Shufang Ding, Qingqing Wang, Chao School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Dept. of Electrical Engineering Beijing China

ISBN: (纸本)9781728144160

As an important performance index of the UAV Ad hoc network, network reliability is a great significance for the performance evaluation of the UAV network system, and provides a direction for the selection of the UAVs formations. In this paper, based on the 3D Gauss Markov moving model, we modeled the motion mode of the UAV group. By using the Weibull distribution to sample the failure of the fleet, and through the correlation matrix which characterizes the connectivity state of network nodes in the time domain, we studied and compare the reliability of the self-organizing network of the UAV group with different formations. It provides a basis for selecting the formations of the UAVs for different network requirements. © 2019 IEEE.

关键词： Reliability

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Probabilistic evaluation of renewable energy curtailment under forward electricity market 10

Probabilistic evaluation of renewable energy curtailment und...

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2020 10th International Conference on power, Energy and Electrical Engineering, CPEEE 2020

作者： Jiang, Jiheng Qiao, Ying Lu, Zongxiang Ran, Liang Ma, Ming Li, Jin Wang, Feng State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing100084 China State Grid Gansu Provincial Electric Power Company Lanzhou730000 China Key Laboratory of Wind Power Integration Operation and Control of Gansu Province Lanzhou730070 China

Forward electricity market has emerged as a pivotal section for the electricity transaction to keep stakeholders away from price risk and electricity shortage. But the forward contract of conventional unit partially limits the unit output before operation, leading to the curtailed generation share of renewable energy source (RES). Modeling and assessing this impact is of great significance for system planning and market supervision. The central thesis of this paper is to find out the impact of forward market on RES curtailment. A probabilistic evaluation model for RES accommodation is proposed, taking the curtailment rate as a main evaluation index. We mainly research financial contract and physical contract, modeling the impact of them on thermal unit minimum load capacity and power load in evaluation model. The simulation is conducted in a simplified system, which reveals the change of RES curtailment with renege penalty, contract price and execution generation curve. © 2020 The Authors, published by EDP Sciences.

关键词： power markets

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Phase Segmentation of Ni/YSZ Anode for Solid Oxide Fuel Cells by Deep Learning

Phase Segmentation of Ni/YSZ Anode for Solid Oxide Fuel Cell...

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243rd ECS Meeting

作者： Wang, Y. Matsui, Y. Hosomizo, A. Kishimoto, M. Han, M. Iwai, H. Department of Mechanical Engineering and Science Kyoto University Nishikyo-ku Kyoto615-8540 Japan State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Energy and Power Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781607685395

A deep learning network is implemented for the phase segmentation of Ni/YSZ anode of solid oxide fuel cells (SOFCs), as manual segmentation of focused ion beam-scanning electron microscopy (FIB-SEM) images is time-consuming. Segmentation is performed on two samples with different volume ratios of Ni to YSZ. The mean intersection over union (mIoU) reaches 0.9363, indicating good agreement between the predicted images and the manually segmented images. Furthermore, the impact of image augmentation on segmentation accuracy is investigated, and it is found that augmentation is necessary when the number of images in the training set is small or the training and testing sets come from different samples. Furthermore, mixing a sixth of manually segmented images from a new sample into the training set can significantly improve the accuracy of automated segmentation for the new sample. This strategy reduces the number of images requiring manual segmentation and improves processing efficiency. © The Electrochemical Society.

关键词： Solid oxide fuel cells (SOFC)

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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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