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13th International Conference on Development in power System Protection 2016 (DPSP)

作者： Jiang Ni Bin Wang Xinzhou Dong State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. To solve this problem, the typical HIF arc flash based on Mayr's arc model is first built, and the typical fault waveforms of HIF in wind farm are presented. Then the characteristics of high impedance faults are analysed to distinguish the occurrence of HIF from other harmonic interference. After that, the performance of the traditional harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is presented to prevent harmonic interference influence in wind farms.

关键词： distribution system Wind farm high impedance faults harmonic algorithm

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Active voltage balancing control for multi HV-IGBTs in series connection

Active voltage balancing control for multi HV-IGBTs in serie...

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IEEE Energy Conversion Congress and Exposition

作者： Shiqi Ji Fred Wang Leon Tolbert Ting Lu Zhengming Zhao Hualong Yu Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN USA State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781509007387

The series connection of insulated gate bipolar transistors (IGBTs) allows the operation at voltage levels higher than the rated voltage of one IGBT. However, the technology has not been widely applied due to transient voltage unbalance. Asynchronous gate drive signals, which cause series-connected IGBTs not to turn-on and turn-off at the same time, result in serious unbalanced voltage sharing. This paper presents an active voltage balancing control for multi series connected HV-IGBTs including the active voltage balancing control (AVBC) circuit integrated in the gate driver and the control for multi series connected IGBTs. The effectiveness of the control has been experimentally validated in a 10 kV dc-link voltage converter using four 4.5 kV HV-IGBTs in series connection.

关键词： active voltage balancing control multi HV-IGBTs series connection

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A dynamic multi-level temporal and spatial coordination method for orderly power utilization based on customer load curtailment cost characteristics

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Dianwang Jishu/power System Technology 2016年第2期40卷 425-432页

作者： Yan, Qingguo Tong, Xing Zhang, Ning Chen, Xiao Yi, Yongxian State Grid Jiangsu Electric Power Company NanjingJiangsu Province210024 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Jiangsu Electric Power Company Research Institute NanjingJiangsu Province210019 China State Grid Key Laboratory of Electric Power Metrology NanjingJiangsu Province211103 China

When there is power supply shortage or emergency event in power system, orderly power utilization needs to be applied to cut down electricity demand to maintain power supply for important electricity consumers. Current orderly power utilization fails to consider curtailment costs for different regions and customers, and ignores temporal continuity and production regularity of customer, leading to inefficient load curtailment scheduling. This paper proposes a dynamic multi-level temporal and spatial coordinated shortage allocation method considering customer load curtailment costs for orderly power utilization. Load curtailment cost function is established from individual customer level up to provincial electrical grid level. An optimization model is proposed to strategically rearrange customer load profiles across multiple periods. Case studies show that the method efficiently coordinates power shortage in temporal and spatial scale, and significantly brings down economic cost due to curtailment allocation. This model could help promote customer satisfaction level in orderly power utilization. © 2016, power System Technology Press. All right reserved.

关键词： Electric power utilization

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Iron loss evaluation and comparison in application of reduced common mode voltage PWM methods 7

Iron loss evaluation and comparison in application of reduce...

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7th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2015

作者： Liu, Fang Lu, Ting Zhao, Zhengming Gu, Qing Yuan, Liqiang Li, Kai State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781467371506

The application of reduced common mode voltage pulse width modulation methods bring much high order harmonics to the variable speed drive system, which causes considerable iron loss inside the electric motor. In this paper, an improved iron loss model considering those high order harmonics is proposed. Iron loss coefficients are obtained based on experimental data by utilizing multiple linear regression and harmonics analysis method. Comparisons of the iron losses between various PWM methods are made for both experimental results and calculated results. It is found that by utilizing RCMV PWM methods, the iron loss of the induction motor becomes larger. The differential values of iron losses between RCMV PWM and CPWM decrease with the increase of the modulation ratio as a result of the reduction of zero space vectors' action time. © 2015 IEEE.

关键词： Pulse width modulation

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A Comprehensive Consensus-based Distributed control Strategy for Grid-connected PV-VSG

A Comprehensive Consensus-based Distributed Control Strategy...

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第35届中国控制会议

作者： Shengwei Mei Tianwen Zheng Laijun Chen Chun Lai Li Yang Si Yan Guo Qinghai Key Lab of Efficient Utilization of Clean Energy (New Energy Photovoltaic Industry Research Center Qinghai University) State Key Lab of Control and Simulation of Power Systems and Generation Equipment (Dept.of Electrical EngineeringTsinghua University) Qinghai Electrical Power Research Institute Qinghai Electric Power Corporation

ISBN: (纸本)9781509009107

This paper presents the concept and control strategy of PV-VSG,which integrates photovoltaic(PV) and virtual synchronous generator(VSG) together without battery energy storage system(BESS).First,the PV-VSG topology and the operation stability regions are clearly analyzed to ensure PV-VSG operate in the secure ***,to control multiple PV-VSGs operating well in grid-connected mode,a novel distributed control strategy based on consensus algorithm is *** consensus-based distributed control strategy can not only makes a group of PV-VSGs converge and operate at the preset ratio of available power,but also regulates the total active power flow on the public connection point(PCC) to keep the same as the referenced *** correctness and effectiveness of the proposed control strategy are verified with the provided simulation results.

关键词： Grid-friendly photovoltaic virtual synchronous generator consensus-based distributed control power dispatch

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An evolution model with high proportion of renewable energy

An evolution model with high proportion of renewable energy

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Chinese control Conference (CCC)

作者： Weiqi Zhang Xinyan Zhang Yukai Xia Shaowei Huang Jinyu Xiao Chang Lu Shengwei Mei College of electrical engineering Xinjiang University Wulumuqi Xinjiang CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing Beijing CN State Power Economic Research Institute Beijing China

Compared with other conventional energy sources, renewable energy, which results in less pollution and has numerous resources, is a significant factor in addressing the current issues of the serious environmental pollution and the resource depletion. Large-scale renewable energy connected to the grid could lead to a the change of the morphological structure and the operation modes of energy transmission. While current power grid evolution models did not consider the characteristics of renewable energy in the evolution strategy. The expansion mechanism of the future transmission network with a high proportion of renewable energy is studied in this paper. The operation cost including renewable energy curtailment are optimized using the production simulations, where the stochastic and intermittent of wind and solar energy are modeled. And the dual variable information is adopted to drive the grid upgrading. The expansion strategies for power grid of Zhejiang province in China are analyzed to balance the construction cost and curtailment cost of renewable energy.

关键词： power grids Load modeling Renewable energy sources Wind power generation Economics Production

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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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Comprehensive power-supply planning for active distribution system considering cooling,heating and power load balance

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Journal of Modern power systems and Clean Energy 2015年第4期3卷 485-493页

作者： Xinwei SHEN Yingduo HAN Shouzhen ZHU Jinghong ZHENG Qingsheng LI Jing NONG State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Grid Planning&Research Center Guizhou Power Grid CooporationCSGGuiyang 550002China

An active distribution system power-supply planning model considering cooling,heating and power load balance is proposed in this paper.A regional energy service company is assumed to be in charge of the investment and operation for the system in the *** expansion of substations,building up distributed combined cooling,heating and power(CCHP),gas heating boiler(GHB)and air conditioner(AC)are included as investment planning *** terms of operation,the load scenarios are divided into heating,cooling and transition ***,the extreme load scene is included to assure the power supply reliability of the *** results demonstrate the effectiveness of the proposed model and illustrate the economic benefits of applying distributed CCHP in regional power supply on investment and operation.

关键词： Active distribution system Combined cooling heating and power(CCHP) power-supply planning Load balance

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Adaptive Sliding Mode control of Flexible Load Driven by Motors considering the damping

Adaptive Sliding Mode Control of Flexible Load Driven by Mot...

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International Conference on Electrical Machines and systems

作者： Youshuang Ding Xi Xiao State Key Lab of Security Control and Simulation of Power Systems and Large Scale Generation Equipment Department of Electrical Engineering Tsinghua University China

ISBN: (纸本)9781467388634

This paper presents an adaptive sliding mode controller for the system of flexible load driven by motors with the damping and friction considered. The controller comprised the sliding mode controller and the Kalman estimator. Firstly, the parameter uncertainties and disturbance are modeled with a bounded variable and then an integral sliding surface is designed. Then, to relax the requirement for the bound of uncertainties, a Kalman state estimator is proposed to estimate the bound of uncertainties and the unmeasurable states. With the proposed control structure, the vibration caused by the flexibility can be suppressed and besides, the controller is robust to a wide range of parameter uncertainty and disturbance. The performance of the control strategy is verified via simulation and experimental results.

关键词： Flexible joint flexible manipulator sliding mode adaptive Kalman filter

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Finite element analysis on damping characteristics for vibro-impact of integral shroud blade

Finite element analysis on damping characteristics for vibro...

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Joint Conference on Society for Machinery Failure Prevention Technology Conference, MFPT 2015 and ISA's 61st International Instrumentation Symposium, IIS 2015 - Technology Evolution: Sensors to systems for Failure Prevention

作者： Wang, Nan-Fei Jiang, Dong-Xiang Chen, Jing-Ming State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

By using theoretical and experimental methods, dynamic characteristics of turbine blades with integral shrouds are studied, and the mechanism of vibro-impact and the effective factors of integrally shrouded blades are mainly presented. By means of finite element calculation, the dynamic frequencies and vibration mode shapes of single shrouded blade are explored under different rotating speeds. The three-dimensional entity unit integral dynamics equation of blades with vibro-impact are established by using nonlinear damping model in this paper. With the help of 3D software Solidworks, the solid model of blade is built. With the aid of FEA software ANSYS, the dynamics and static characteristics of single blade are obtained. Meanwhile, by building the model to set different shroud clearance and exciting force amplitude, the relationships between displacement of blade tip and influence of such as blade shroud clearance and exciting force amplitude are demonstrated. The results of the analysis indicate that the collision structural is an ideal damping structure. As the clearance between blade shrouds is smaller, the damping effect is better. Moreover, results show that blades adopting collision damping mechanism can achieve good damping effect when the blades are subjected to greater exciting force.

关键词： Finite element method

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