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第三十四届中国控制会议

作者： LIU Bin LIU Feng MEI Shengwei State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

ISBN: (纸本)9781467374439

Wind power generation uncertainty has imposed great challenge on power systems' operation and should be considered when making an operation *** this paper,we focus on optimal power flow(OPF) problem in radial power networks while considering wind power generation *** cope with this uncertainty,the stochastic AC-constrained OPF(ACOPF) problem considering both continuous and discrete devices is formulated based on our previous *** second order cone relaxation is employed to relax the original mixed integer nonconvex nonlinear programming(MINNLP) problem to a mixed integer second order cone programming(MISOCP) problem which can be solved by commercial solvers with high computation *** modified IEEE 33 bus distribution system is studied in this paper which validate the effectiveness of the proposed model.

关键词： optimal power flow wind power stochastic optimization radial power networks uncertainty set

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Enhanced phosphate removal using zirconium hydroxide encapsulated in quaternized cellulose

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Journal of Environmental Sciences 2020年第3期32卷 102-112页

作者： Shuoxun Dong Qinghua Ji Yili Wang Huijuan Liu Jiuhui Qu Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China College of Environmental Science and Engineering Beijing Key Lab for Source Control Technology of Water PollutionBeijing Forestry UniversityBeijing 100083China

Zirconium-based materials are efficient adsorbent for aqueous phosphate ***,current zirconium-based materials still show unsatisfied performance on adsorption capacity and ***,we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose(QC-Zr) for the selective phosphate *** hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional(3D) cross-linked cellulose *** maximum P adsorption capacity of QC-Zr was 83.6 mg P/***,the QC-Zr shows high P adsorption performance in a wide pH range,generally due to the electrostatic effects of quaternized *** enhanced adsorption of P was also achieved in the presence of competing anions(including Cl^-,NO3^-,SO4^2-,SO4^4-) and humic acid(HA) even at a molar ratio up to 20 *** column adsorption capacity of QC-Zr reached 4000 bed volumes(BV) at EBCT=0.5 min as the P concentration decreased from 2.5 to 0.5 mg/*** study revealed that both-N^+(CH3)3 groups and zirconium hydroxide were involved in phosphate adsorption via electrostatic interactions between -N^+(CH3)3 and phosphate,and the formation of zirconium hydrogen phosphate(Zr(HPO4)x).The 31 P nuclear magnetic resonance(NMR) study implied that P surface-precipitated and inner-sphere complexed with zirconium hydroxide at a ratio of 3:1.

关键词： Adsorption Phosphate removal Zirconium hydroxide aerogel Quaternized cellulose

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Statistical characteristics of transient enclosure voltage in ultra-high-voltage gas-insulated switchgear

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Plasma Science and Technology 2017年第6期19卷 74-81页

作者： Yuanji CAI Yonggang GUAN Weidong LIU State Key Lab of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 People＇s Republic of China

Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary *** is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）*** this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike *** TEV waveforms during disconnector operations are recorded by a self-developed measurement system ***,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are *** transmission line theory is introduced to analyze the TEV and is validated by the experimental ***,the relationship between the TEV and the repeated strike process is *** proves that the pulse voltage of the TEV is proportional to the corresponding breakdown *** results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.

关键词： transient enclosure voltage (TEV) gas-insulated switchgear (GIS) ultra-high-voltage (UHV) repeated strike process disconnector

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Commutation Failure Mitigation Method Based on Improved Commutation Area in HVDC system 8

Commutation Failure Mitigation Method Based on Improved Comm...

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

作者： Wang, Haozong Dong, Xinzhou Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Commutation failure (CF) is one of the major concerns in high-voltage direct current (HVDC) transmission system. Of many methods to mitigate CF, advancing firing angle is preferred one since it can be easily implemented in current HVDC controllers without extra hardware modification. However, methods in previous works either lack for quantitative analysis or based on much strong hypothesis. In this paper, we propose a novel CF mitigation method based on improved commutation area. The salient feature of proposed strategy is that DC current is not considered as a constant under fault conditions. simulations on PSCAD/EMTDC software demonstrate the good performance of proposed method. © 2019 IEEE.

关键词： Electric commutation

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DC Bias Elimination and Soft Switching in Transient state of Dual-Active-Bridge DC-DC Converter 48

DC Bias Elimination and Soft Switching in Transient State of...

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48th Annual Conference of the IEEE Industrial Electronics Society, IECON 2022

作者： Wang, Zhe Li, Chi Liu, Jiye Zheng, Zedong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (数字)9781665480253

ISBN: (纸本)9781665480253

Dual active bridge is a promising isolated bidirectional DC/DC converter which has attracted more and more attention due to its advantages of zero-voltage switching, great voltage regulation ability, high power density, and fast dynamic response. However, the DC bias problem is seldom mentioned, which may lead to system instability and decreased efficiency. Besides, whether the converter can realize soft switching in the dynamic process is unclear. This paper proposed a novel phase-shift loading mode which can not only realize the DC bias elimination but also achieve zero voltage switching (ZVS) during a transient state. Finally, a 4.5 kW prototype is built and experimental results are provided to verify the conclusion. © 2022 IEEE.

关键词： Zero voltage switching

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Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

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Journal of Modern Power Systems and Clean Energy 2018年第1期6卷 61-72页

作者： Tianwen ZHENG Laijun CHEN Yan GUO Shengwei MEI State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Qinghai Key Lab of Efficient Utilization of Clean Energy New Energy Photovoltaic Industry Research Center Qinghai University

Virtual synchronous generator(VSG)is gridfriendly for integrating distributed generations(DGs)since it can emulate the operation mechanism of traditional synchronous generator(SG).However,the traditional VSG control strategy,which is mainly suitable for balanced voltage conditions,may lead to power oscillations,current unbalance and even overcurrent under unbalanced voltage *** overcome this difficulty,a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is *** on the basic VSG control algorithm,the control strategy integrates two novel control modules,which are current reference generator(CRG)and power reference generator(PRG).The proposed control strategy can flexibly meet different operation demands,which includes current balancing,constant active or reactive *** the injected currents are kept within safety values for a better utilization of the VSG power ***,the experimental platform is *** results demonstrate the validness and effectiveness of the proposed control strategy.

关键词： Virtual synchronous generator Unbalanced control Current reference generator Power reference generator Voltage sags

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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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Design and validation of real-time dynamic spectrum management in OFDM-based HNPLC systems

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High Technology Letters 2015年第4期21卷 379-387页

作者：刘雯静 Guo Jingbo Yan Yanxin Zhang Tongfei State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University ROHM Semiconductor(Shanghai) Co. Ltd.Design Center

Time-varying frequency selective attenuation and colored noises are unfavorable characteristics of power line communication(PLC) channels of the low voltage *** overcome these disadvantages,a novel real-time dynamic spectrum management(DSM) algorithm in orthogonal frequency division multiplexing(OFDM)-based high-speed narrow-band power line communication(HNPLC) systems is proposed,and the corresponding FPGA circuit is designed and *** of the proposed DSM is validated with a large amount of network experiments under practical PLC *** the noise in each narrow subcarrier is approximately Gaussian,the proposed DSM adopts the BER/SER expression formulized via the AWGN channel to provide a handy and universal strategy for power *** real-time requirement is guaranteed by choosing subcarriers in group and employing the same modulation scheme within each *** measures are suitable for any modulation scheme no matter the system criterion is to maximize data rate or minimize power/*** design and hardware implementation of the proposed DSM are given with some flexible and efficient *** DSM circuit is carried out with Xilinx *** and practical experiments validate that the proposed real-time DSM significantly improves system performance.

关键词： real-time dynamic spectrum management high-speed narrowband power line com-munication (HNPLC) subcarrier grouping rate adaptive multi-carrier

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One representative water supply system in China with nitrosamine concern: Challenges and treatment strategies

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Journal of Environmental Sciences 2020年第2期32卷 12-20页

作者： Yu Qiu Er Bei Yufang Wang Jun Wang Xiaojian Zhang Chao Chen State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Beijing Key Lab for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Research Institute for Environmental Innovation(Suzhou) TsinghuaSuzhou 215163China

Four sampling campaigns were conducted in two years to understand the fluctuation of N-Nitrosamines(NAs) and their precursors in one drinking water treatment plant(DWTP) in East China in different *** water supply system has been facing several nitrosamine challenges related with source water, including the switch of water source,high concentration of ammonium, formed NAs and NA formation potential(FP) in source ***, the use of ozonation in the DWTP and chloramination in networks will increase the NDMA concentration in tap *** address these challenges, the biopretreatment was applied in this DWTP to decrease the concentration of ammonium and *** following biological activated carbon(BAC) will neutralize the nitrosamine increase brought by *** use of free chlorine in disinfection process will also decrease the NDMA formation compared with *** results will benefit other cities in China and other countries with similar impacted water sources.

关键词： Drinking water treatment plant Formation potential Networks N-Nitrosamines Precursor

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Phosphate removal by a La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel:Enhanced surface charge density and Donnan membrane effect

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Journal of Environmental Sciences 2022年第3期34卷 26-39页

作者： Yanqing Zhou Yili Wang Shuoxun Dong Haotian Hao Junyi Li Chenyang Liu Xiaolin Li Yao Tong College of Environmental Science and Engineering Beijing Key Lab for Source Control Technology of Water PollutionBeijing Forestry UniversityBeijing 100083China Center for Water and Ecology State Key Joint Laboratory of Environment Simulation and Pollution ControlSchool of EnvironmentTsinghua UniversityBeijing 100083China State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

Cationic hydrogels have received great attention to control eutrophication and recycle *** this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a potential adsorbent for enhanced phosphate removal from aqueous ***(OH)_(3)@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g,and reached equilibrium within 2 ***(OH)_(3)@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions(including SO_(4)^(2-),Cl^(-),NO_(3)^(-),HCO_(3)^(-),SiO_(4)^(4-) and HA).The adsorption-desorption experiment indicated that La(OH)_(3)@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent,and 73.3%adsorption capacity remained after five ***,La(OH)_(3)@MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%.Actually,MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57%within 24 h,indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate ***,the bifunctional structure of La(OH)_(3)@MMCH enabled it to capture phosphate through electrostatic attraction and ligand *** the results prove that La(OH)_(3)@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.

关键词： Cationic hydrogel La(0H)_(3) Phosphate adsorption Enhanced Donnan membrane effect

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