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4th International Symposium on Insulation and Discharge Computation for power equipment, IDCOMPU 2023

作者： Zhang, Zhen Zhou, Yuanxiang Chen, Jianning Li, Yuhang Dai, Yasong The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi830047 China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819974009

The temperature distribution of submarine cables is an important parameter reflecting its operation status. The acquisition of temperature distribution trends for submarine cables under varying seawater flow rates holds important engineering significance. In this paper, the geometric model is constructed using a 220 kV three-core AC armored submarine cable laid on the seabed. The simulation model of AC three-core submarine cable temperature field is proposed based on the coupling of electro-thermal-flow multi-physics field. Finally, the study investigates how the steady-state temperature distribution of submarine cables varies with different seawater flow velocities. The results show that the temperature is radially distributed at the seawater velocity of 0m/s, and the temperatures of different phase conductors are different by the relative position, which are 89.9 °C, 89.6 °C and 89.08 °C, respectively. As the seawater flow velocity increases, the heat taken away from the cable surface by convection increases. When the seawater flow velocity is 1 × 10−6m/s, 0.0001 m/s, 0.001 m/s, 0.001 m/s and 0.001 m/s, the maximum conductor temperatures are 69.5 °C, 44.6 °C, 38.5 °C, 33.6 °C and 32.7 °C, and the ampacity is 871.7 A, 1216 A, 1382.8 A, 1590.7 A and 1640.9 A, respectively. The simulation results can provide reference for submarine cable transmission engineering design. © 2024, Beijing Paike Culture Commu. Co., Ltd.

关键词： Temperature distribution

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Pilot study for the treatment of sodium and fluoridecontaminated groundwater by using high-pressure membrane systems

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Frontiers of Environmental Science & Engineering 2015年第1期9卷 155-163页

作者： Xiaomao WANG Hongwei YANG Zhenyu LI Shaoxia YANG Yuefeng XIE State Key Joint Laboratory of Environmental Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China National Engineering Laboratory for Biomass Power Generation Equipment School of Renewable Energy North China Electric Power University Beijing 102206 China Environmental Engineering Programs The Pennsylvania State University Middletown PA 17057 USA

High-pressure membrane process is one of the cost-effective technologies for the treatment of groundwater containing excessive dissolved solids. This paper reports a pilot study in treating a typical groundwater in Huaibei Plain containing excessive sodium, sulfate and fluoride ions. Three membrane systems were set up and two brands of reverse osmosis （RO）, four low-pressure RO （LPRO） and one tight nanofiltration （NF） membranes were tested under this pilot study. An apparent recovery rate at about 75% was adopted. Cartridge filtration, in combination with dosing antiscalent, was not sufficient to reduce the fouling potential of the raw water. All RO and LPRO systems （except for the two severely affected by membrane fouling） demonstrated similar rejection ratios of the conductivity @98.5%）, sodium （-98.5%） and fluoride （-99%）. Membrane fouling substantially reduced the rejection performance of the fouled membranes. The tight NF membrane also had a good rejection on conductivity （95%）, sodium （94%） and fluoride （95%）. All membranes rejected sulfate ion almost completely （more than 99%）. The electricity consumptions for the RO, LPRO and NF systems were 1.74, 1.10 and 0.72 kWh·m3 treated water, respectively. The estimated treatment costs by using typical RO, LPRO and tight NF membrane systems were 1.21, 0.98 and 0.96 CNY·m 3 finished water, respectively. A treatment process consisting of either LPRO or tight NF facilities following multi-media filtration was suggested.

关键词： reverse osmosis (RO) nanofiltration (NF),water quality standards sodium fluoride cost estimation

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Evaluation of information value for solar power plants in market environment 4

Evaluation of information value for solar power plants in ma...

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4th IEEE Conference on Energy Internet and Energy System Integration, EI2 2020

作者： Wang, Bohong Guo, Qinglai Yang, Tianyu Sun, Hongbin Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Department of Electrical Engineering Beijing100084 China

ISBN: (纸本)9781728196060

Uncertainty is not negligible in power systems, it affects the generation, transmission and utilization of electricity. Especially in electricity markets, the randomness and variability of generation or load will cause notable forecast errors and lead to economic losses of market participants. Due to the data explosion in recent few years, data have gradually become valuable information that can be mined, analyzed, and applied. Meanwhile, the utility that more abundant and accurate information could eliminate uncertainty is emerging. In this paper, solar power plants (SPPs) are selected as the object, the general mechanism in electricity markets is briefly introduced and the corresponding market optimization model is constructed. With the optimization model analytically solved, the impact of uncertainty is analyzed and the expressions of information value are derived. Besides, uniform, normal, logistic, and Laplace distribution are used in the evaluation of information value and compared. Finally, the case study is conducted to verify the theoretical results of information value and illustrate its significance. © 2020 IEEE.

关键词： power markets

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Cause Identification of Single-line-to-ground Fault in Distribution System

Cause Identification of Single-line-to-ground Fault in Distr...

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2021 International Conference on power System Technology, powerCON 2021

作者： Liu, Kun Ren, Xuan Wang, Bin Power Dispatch Control Center of Guangdong Power Grid Co. Ltd Key Lab for Protective Relaying Real Time Digital Simulation of Guangdong Power Grid Co. Ltd. Guangzhou China Tsinghua University Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electric Engineering Beijing China

ISBN: (纸本)9781665407373

Cause identification of single-line-to-ground fault in the distribution system is of great significance to the electric workers for fault isolation and rapid maintenance. The key of fault cause identification is to accurately and quickly distinguish human electric shock faults from non-biological faults. In this paper, human electric shock faults and non-biological faults are modeled and fault characteristics are analyzed. Based on the differences between shape and rotation characteristic of the volt-ampere characteristic curves, a fault cause identification method which can distinguish human electric shock faults from non-biological faults is proposed. simulations show the effectiveness of the method. © 2021 IEEE.

关键词： Electric grounding

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The Optimal Design of the Second-Order Generalized Integrator Phase-Locked Loop Under power Voltage Distortion Conditions 5

The Optimal Design of the Second-Order Generalized Integrato...

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5th IEEE Conference on Energy Internet and Energy System Integration, EI2 2021

作者： Zhang, Xin Gong, Lijiao Wang, Bin Si, Jindong College of Mechanical and Electrical Engineering Shihezi University Shihezi China Shihezi China State Key Laboratory of Safety Control and Simulation of Power Systems and Power Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781665434256

Phase-locked loop (PLL) based on traditional second-order generalized integrator (SOGI) cannot obtain the voltage, frequency and phase information accurately when there are multiple harmonic interference and DC offset in grid voltage. To solve this problem, this paper proposes an improved PLL that can suppress harmonic and eliminate DC component to extract the synchronous signal accurately. First of all, based on the derivation of distorted grid voltage expression, the problem offluctuation in extracting synchronous signal from three-phase unbalanced voltage with harmonic by traditional PLL is analyzed. Then, the design of improved PLL is proposed, which is composed of an improved second-order generalized integrator and a frequency correction component which can suppress harmonics and eliminate disturbances under the condition of grid voltage distortion, and has self-adaptability in large frequency offset. Determine the control parameters to ensure that the proposed PLL structure has a better rejection to harmonic distortion than previous approaches, and realize accurate tracking of grid fundamental frequency synchronization information. Finally, the behavior of the proposed system is verified with MATLAB/Simulink simulation and Hardware-in-Loop Experimental Platform which prove the proposed PLL can realize the synchronous tracking performance of grid frequency and phase quickly and accurately in the non-ideal grid environment, and the results are consistent with the theoretical analysis. © 2021 IEEE

关键词： Phase locked loops

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Nonlinear E-field simulation of HVDC Converter Transformer Busing and Its Structure Optimization With RBF Neural Network and NSGA-II Algorithm 13

Nonlinear E-field Simulation of HVDC Converter Transformer B...

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13th International Conference on power and Energy systems, ICPES 2023

作者： He, Yongsheng Zhang, Shiling Lu, Zongxiang Wang, Pengbo State Grid Chongqing Electric Power Company Chongqing Electric Power Research Institute Chongqing China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Haidian China Transmission Equipment and System Security and New Technology Dept Name of State Key Laboratory of Power Chongqing China

ISBN: (纸本)9798350345063

Static DC and PR are typical operation conditions of HVDC converter transformer bushing outlet device, moreover, the electrical parameters of RIP, transformer oil and OIP have the nonlinear relationship with E-field stress and temperature. Under the temperature gradient, the electrical parameters will modify the static DC and PR E-field distribution of the composite insulation. In order to simulate static DC and PR electric field of the composite insulation structure, this paper established the full model of the converter transformer outlet. Then, the structure parameters of converter transformer outlet have been optimized using combined RBF neural network and NSGA-II algorithm. Moreover, electric field verification calculation has been carried out under AC and PR conditions. The results show that under uniform temperature condition, E-field strength is larger than that under iso-thermal condition. The overshoot coefficient of the bushing end and barrier reach 65% and 45%, respectively. The study can provide reference for the design of outlet structure of the converter transformer. © 2023 IEEE.

关键词： DC transformers

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Application and Practice of Digital Twin Technology in Monitoring Status of power equipment in Converter Valve Hall

Application and Practice of Digital Twin Technology in Monit...

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2023 International Conference on Intelligent Communication and Computer Engineering, ICICCE 2023

作者： Yongsheng, He Baojia, Deng Zongxiang, Lu Shiling, Zhang Liangjun, Dai State Grid Chongqing Electric Power Company Electric Power Research Institute China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Deptartment of Electrical Engineering Tsinghua University China

ISBN: (纸本)9798350395617

The internal power equipment of ultrahigh voltage converter valve hall is numerous and complex in structure, involving the various information elements such as the temperature and vibration. Moreover, the gas inside ultra-high voltage converter bushing is SF6 gas. Under the current over-load condition of the converter bushing, SF6 gas will decompose. This article focuses on the SF6 gas equipment inside the ultrahigh pressure converter valve hall as the research object, and analyzes specific types and content of SF6 gas decomposition products. In order to effectively detect gas content in the digital twin model of the converter transformer bushing, the new portable SF6 gas chromatograph, laser detection technology and device for HF gas, and partial discharge detection technology research using the acoustic electric coupling method are carried out, providing the effective means for onsite detection of hidden faults in operating equipment. Research has shown the digital twin technology can effectively detect the absorption spectra of gases such as O2, H20, CO, CO2, CF4, SO2, H2S, SOF2, and SO2F2. On the other hand, through digital twin partial discharge detection technology, it is effectively found that the SO2 inside the UHV converter sleeve is 29μL/L, H2S is 4μL/L, CO is 36μL/L, HF=0, detected SO2 and H2S components, determined as the insulation heating defect. The research results of paper provide theoretical and data support for operation status monitoring of SF6 gas insulated power equipment inside the ultra-high voltage converter valve hall. © 2023 IEEE.

关键词： Sulfur hexafluoride

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A Two-level Energy Storage System for Wind Energy systems

A Two-level Energy Storage System for Wind Energy Systems

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2011 International Conference on Energy and Environment(ICEE 2011)

作者： Xi Xiao Hu Yi Qing Kang Jinfeng Nie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University

Wind power outputs fluctuate with the changing of wind speed. The use of energy storage equipment is considered a reasonable solution to suppress wind power fluctuations. An energy storage mode may have its disadvantages over the others, for example, capacity limits, dynamic response, higher prices or shorter lifetime. Moreover, wind power fluctuations are present at different frequencies, to demand the energy storage to offer power support in different time ranges. To improve the performance, in this paper, a combined energy storage mode is discussed to meet the short-term and longterm energy storage requirement for wind power. Short-term energy storage is designed to meet the fast-changing power, using such as super capacitors. Long-term energy is designed to meet the large-scale capacity requirement using Li-ion battery or Vanadium Redox Battery(VRB). By analyzing the actual data of wind power outputs, the capacities of the two kinds of energy storage means are given as an example of the method.

关键词： wind power energy storage capacity designing

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A Two-level Energy Storage System for Wind Energy systems

A Two-level Energy Storage System for Wind Energy Systems

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2011 International Conference of Environmental Science and Engineering（ICESE 2011）

作者： Xi Xiao Hu Yi Qing Kang Jinfeng Nie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University

Wind power outputs fluctuate with the changing of wind speed. The use of energy storage equipment is considered a reasonable solution to suppress wind power fluctuations. An energy storage mode may have its disadvantages over the others, for example, capacity limits, dynamic response, higher prices or shorter lifetime. Moreover, wind power fluctuations are present at different frequencies, to demand the energy storage to offer power support in different time ranges. To improve the performance, in this paper, a combined energy storage mode is discussed to meet the shortterm and long-term energy storage requirement for wind power. Short-term energy storage is designed to meet the fast-changing power, using such as super capacitors. Long-term energy is designed to meet the large-scale capacity requirement using Li-ion battery or Vanadium Redox Battery(VRB). By analyzing the actual data of wind power outputs, the capacities of the two kinds of energy storage means are given as an example of the method.

关键词： Wind power energy storage capacity designing

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Research on shielding failure of UHVDC based on leader progression model

Research on shielding failure of UHVDC based on leader progr...

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2012 31st International Conference on Lightning Protection, ICLP 2012

作者： Geng, Yinan Zhuang, Chijie Institute of Nuclear and New Energy Technology Tsinghua University Beijing China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781467318976

Shielding failure is one of key problems of UHV transmission lines. Considering the high operating voltage and high tower of UHV transmission lines, the inception criterion of upward leader is proposed in this paper. The process of shielding failure is simulated by the method based on leader progression model and shielding failure rate is calculated. This method is verified by comparing the calculation results with the operated data of UHV transmission lines in Japan. The shielding failure characteristics of UHVDC transmission lines in China under different terrain conditions are researched. © 2012 IEEE.

关键词： Electric lines

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