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Weather type partition method considering sequential features in photovoltaic forecasting

The Journal of Engineering 2017年第13期2017卷 1259-1263页

作者： Hao Li Zongxiang Lu Ying Qiao Ningbo Wang Kun Ding State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing 100084 People's Republic of China Wind Power Technology Center Gansu Electric Power Corporation Lanzhou 730050 People's Republic of China

The prediction method based on the partition of weather types has been widely used in photovoltaic prediction. Here, the temporal characteristics of PV data is studied, the physical meaning of the sequential difference sequences is analysed, and a characteristic index system including sequential characteristics index is proposed. The weather types are partitioned based on self-organising map neural network algorithm. Case study shows that the partition method is helpful to improve the discrimination of weather types and to improve prediction accuracy.

关键词： load forecasting photovoltaic power systems prediction theory self-organising feature maps power engineering computing self-organising map neural network algorithm characteristic index system sequential difference sequence analysis PV data characteristics photovoltaic prediction method photovoltaic forecasting weather type partition method

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A usage-based transmission cost allocation scheme considering impacts of DERs

A usage-based transmission cost allocation scheme considerin...

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2016 Tsinghua University-IET Electrical Engineering Academic Forum

作者： Wang, J.X. Zhong, H.W. Xia, Q. State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781785614170

With the rapid development of distributed energy resources (DERs), it is of vital importance to develop a well-designed transmission cost allocation scheme to reflect the contributions of DERs to the power system. In this paper, a usage-based transmission cost allocation scheme is proposed considering the capability of DERs. Based on the different intentions of transmission capacity, the transmission costs can be classified into four fractions: operating, contingency, planning and invalid transmission costs. On operating conditions, the transmission costs are identified and allocated according to the actual usage of consumers at each node. On contingency conditions, the transmission cost allocation will be influenced by the behaviors of DERs since DERs can provide emergent power support to help alleviate transmission congestion. On planning conditions, the transmission costs are useful in the future. The residual costs, i.e., the invalid transmission costs, should not allocated by consumers because this fraction is caused by the over investment of transmission owners. The case studies based on the IEEE 30-bus system validates the effectiveness of the proposed scheme and model. © 2016, Institution of Engineering and Technology. All rights reserved.

关键词： Investments

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Blackout Risk Analysis and control of power system Integrated with Wind Farm 28

Blackout Risk Analysis and Control of Power System Integrate...

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第28届中国控制与决策会议

作者： Zhong Yuxin Zhang Xuemin Mei Shengwei Xia Deming Wang Shuai Shi Rui Dept.of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation EquipmentsTsinghua University Northeast Branch of State Grid Corporation of China State Power Economic Research Institute

ISBN: (纸本)9781467397155

With the increase of wind power penetration,the characteristics of the wind farm have brought a significant impact on the security of power *** is urgent to study how to reduce the risk of cascading failures while improving the environmental *** this paper,a cascading failure model containing wind farm is proposed,which considers wind power characteristics,such as the structure of wind farm,the randomness of power of wind farm,the virtual inertia control of wind turbine,and the disconnection response of wind turbine after short-circuit *** order to identify the key factors of blackout,decision tree is used to analyze results generated from this blackout *** control is adopted to decrease the probability or effect of critical attributes that can be found in decision *** blackout risk of IEEE 30 test system integrated with wind farm is *** key factors,such as disconnection of wind turbines from the grid and certain transmission lines,are identified by decision ***,the effectiveness of the virtual inertial control of wind turbine,reactive power compensation and line construction is verified by simulation.

关键词： Wind Farm Disconnection of Wind Turbines Virtual Inertial control Blackout Risk Decision Tree

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An Evolution Model with High Proportion of Renewable Energy 35

An Evolution Model with High Proportion of Renewable Energy

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第35届中国控制会议

作者： ZHANG Weiqi ZHANG Xinyan XIA Yukai HUANG Shaowei XIAO Jinyu LU Chang MEI Shengwei College of electrical engineering Xinjiang University State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept.of Electrical Engineering Tsinghua University) State Power Economic Research Institute

ISBN: (纸本)9781509009107

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 ***-scale renewable energy connected to the grid could lead to a the change of the morphological structure and the operation modes of energy *** current power grid evolution models did not consider the characteristics of renewable energy in the evolution *** expansion mechanism of the future transmission network with a high proportion of renewable energy is studied in this *** operation cost including renewable energy curtailment are optimized using the production simulations,where the stochastic and intermittent of wind and solar energy are *** the dual variable information is adopted to drive the grid *** 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： Renewable energy Network evolving model Transmission planning Production simulation

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Repeated Strike Process During Disconnector Operation in Ultra-High Voltage Gas-Insulated Switchgear

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Plasma Science and Technology 2016年第3期18卷 247-253页

作者：关永刚蔡元纪陈维江刘卫东李志兵岳功昌张俊民 State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China State Grid Corporation of China Beijing 100031China China Electric Power Research Institute Beijing 100192China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

Very fast transient over-voltage （VFTO）, induced by disconnector operations in gas- insulated switchgears, has become the limiting dielectric stress at ultra-high voltage levels. Much work has been done to investigate single-strike waveforms of VFTO. However, little study has been carried out investigating the repeated strike process, which would influence VFTO significantly. In this paper, we carried out 450 effective experiments in an ultra-high voltage test circuit, and conducted calculations through the Monte Carlo simulation method, to investigate the repeated strike process. Firstly, the mechanism of the repeated strike process is proposed, based on the ex- perimentai results. Afterwards, statistical breakdown characteristics of disconnectors are obtained and analyzed. Finally, simulations of the repeated strike process are conducted, which indicate that the dielectric strength recovery speed and polarity effect factor have a joint effect on VFTO. This study enhances the understanding of the nature of VFTO, and may help to optimize the disconnector designed to minimize VFTO.

关键词： disconnector （DS） repeated strike process discharge statistical breakdowncharacteristics ultra-high voltage （UHV） very fast transient over-voltage （VFTO）

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Measurement techniques on transient process of lightning striking overhead transmission lines

Measurement techniques on transient process of lightning str...

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CIGRE Session 46

作者： Xie, S.J. Li, J.M. Zhang, Y. Zeng, R. Zhuang, C.J. Wang, H. State Grid Sichuan Electric Power Research Institute State Grid Sichuan Electric Power Company China State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Tsinghua University China

Obtaining the lightning strike density along an overhead transmission line and identifying the lightning strike types are the key to evaluating the lightning protection performance and proposing reasonable protection schemes of transmission lines. In addition, the waveform characteristics of lightning invasion overvoltage are the basis to establish the standard on the insulation tests of power equipment. Measuring the transient process of lightning striking overhead transmission lines is the basis to carry out the work mentioned above. In this paper, a distributed measurement method of transient current on conductors caused by lightning strikes is proposed. The measuring units are installed on the field conductors of transmission lines every 30 km to obtain less-distorted transient current waveforms. In order to enable measuring units to work in field isolated environment, a power supply coil using Faraday electric-magnetic effect and a wireless communication module is designed and developed. By far, 4776 measuring units have been installed on 597 transmission lines of China's power grid. According to measured transient current waveforms, the lightning strike point can be located using the double-end or single-end travelling wave location method, and the lightning strike type can also be identified. Moreover, a novel measurement method of lightning transient voltage based on the integrated optical electric field sensor (IOEFS) is proposed. In this method, the transient voltage waveforms are inversed from space electric field waveforms measured by IOEFSs. A series of performance tests of IOEFS have been carried out. The test results indicate that the response speed can reach several nanoseconds, and the frequency response can cover 5Hz∼100MHz which is wide enough for the measurement of the lightning transient voltage. In order to test the field measurement effect, the measurement equipment is used to measure a transient voltage when a group of capacitor voltage trans

关键词： Frequency response

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High impedance fault detection on distribution systems with harmonic interference in wind farms 13

High impedance fault detection on distribution systems with ...

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13th International Conference on Development in power system Protection 2016, DPSP 2016

作者： Ni, Jiang Wang, Bin Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China

ISBN: (纸本)9781785618260

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： Electric utilities

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Voltage balance optimisation among subsystems of wind-photovoltaic-ES hybrid generating system

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The Journal of Engineering 2017年第13期2017卷 854-858页

作者： Han Wu Yan Li Zongxiang Lu Haiyan Tang State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 People's Republic of China North China Electric Power Research Institute Co. Ltd Beijing 100045 People's Republic of China State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems (China Electric Power Research Institute) Haidian District Beijing 100192 People's Republic of China

Wind-photovoltaic-energy storage (ES) hybrid generating system has numerous reactive power sources. It is crucially important for coordinated control of these reactive power sources. According to the test results, there are unbalanced control problem in subsystem voltage of the hybrid generating system. The problem caused reactive power circulation and loop current. A subsystem voltage balance optimisation strategy is proposed to solve the problem. The case study shows the efficiency of the proposed strategies.

关键词： electric potential wind power photovoltaic power systems reactive power electric power generation reactive power sources wind-photovoltaic-ES hybrid generating system subsystems voltage balance optimisation

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Electrical tree initiation and propagation in silicone rubber under long-term AC aging

Electrical tree initiation and propagation in silicone rubbe...

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2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016

作者： Zhang, Yunxiao Zhou, Yuanxiang Zhang, Ling Ming, Chen Zhang, Xu Yanchao, Sha State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China North China Electric Power Research Institute Co Ltd. Beijing100045 China

ISBN: (纸本)9781509046546

Electrical tree break-down is the major failure problem in cable accessories, however, mechanisms of the electrical tree initiation and propagation are still lack of deeply research, especially in silicone rubber (SIR) which is widely used as insulation material for cable accessories. Long-term aging (0- 1000 h) experiments under the different voltages were conducted to observe electrical tree initiation and propagation processes. In trees initiation stage, with increasing of applied voltage, electrical tree initiation probability becomes larger, while tree initiation time dramatically decreases. The experiment observations demonstrated four shapes of trees which are dominated. As applied voltage increasing, the numbers of electrical trees life-cycles increased and exponential relationship was found between tree length and magnitude of applied voltage. It is noted that charges, whose energy exceeding a certain critical value, destroy microstructure of dielectric accumulatively via injection and extraction, and cause electrical trees initiate when it accumulates to a visible extent. © 2016 IEEE.

关键词： Life cycle

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Stabilization and assessment of interaction dynamics for More Electric Aircraft

Stabilization and assessment of interaction dynamics for Mor...

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International Conference on power Electronics and Motion control (IPEMC)

作者： Xuan Zhang Lie Xu Yongdong Li Zedong Zheng Kui Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781509012114

This paper proposes a novel active stabilization method based on reshaping the output impedance of the source-side PWM rectifier for More Electric Aircraft (MEA) power system. A nonlinear compensation signal is injected into AC voltage command of PWM rectifier to adding a virtual resistor paralleled with DC bus capacitor. Thus, the instability caused by constant power loads (CPLs) can be neutralized. Compared to conventional active damping methods, the value of compensation signal can be expressed by the virtual resistor so that the physical mechanism of stability improvement can be clarified. Besides, all remote sensors providing load input voltages can be removed. Stability and sensitivity of the proposed active stabilization method are analyzed qualitatively. The interaction dynamics of passive devices, such as LC filters of CPLs and DC capacitors on source side are discussed. simulation results validate the effectiveness of the proposed method.

关键词： Damping Pulse width modulation Rectifiers power system stability Capacitors Stability analysis Mathematical model

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