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Harmonic influence analysis of unified power flow controller based on modular multilevel converter

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Journal of Modern power Systems and Clean Energy 2016年第1期4卷 10-18页

作者： Yubo YUAN Peng LI Xiangping KONG Jiankun LIU Qun LI Ye WANG state grid Jiangsu electric power Company research Institute Nanjing 211103JiangsuChina

The unified power flow controller(UPFC)based on modular multilevel converter(MMC) is the most creative flexible ac transmission system(FACTS) device. In theory, the output voltage of the series MMC in MMCUPFC can be regulated from 0 to the rated value. However,there would be relatively large harmonics in the output voltage if the voltage modulation ratio is small. In order to analyze the influence of MMC-UPFC on the harmonics of the power grid, the theoretical calculation method and spectra of the output voltage harmonics of MMC are presented. Subsequently, the calculation formulas of the harmonics in the power grid with UPFC are proposed. Based on it, the influence of UPFC on the grid voltage harmonics is evaluated, when MMC-UPFC is operated with different submodular numbers and voltage modular ratios. Eventually, the proposed analysis method is validated using digital simulation. The study results would provide guideline for the design and operation of MMC-UPFC project.

关键词： Unified power flow controller(UPFC) Modular multilevel converter(MMC) Harmonic features Voltage modulation ratio Submodular number

Simulation analysis on policy interaction effects between emission trading and renewable energy subsidy

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Journal of Modern power Systems and Clean Energy 2013年第2期1卷 195-201页

作者： Jie HUANG Feng XUE Xiaofang SONG NARI Group Corporation(state grid electric power research Institute) Nanjing 210003China

Greenhouse gas emission regulation and renewable energy promotion policies have been implemented in many *** these two kinds of regulation policies have complex interactions between each other,and can either enhance or reduce the overall emission reduction *** not well tuned,these regulation policies may deviate from their original intention and lead to unnecessary social ***,the policy effectiveness,cost effectiveness,and dynamic efficiency of different policy mixtures between emission trading and renewable energy subsidy are studied based on a novel dynamic simulation platform of power economy and power *** results show that these two kinds of regulation policy can coexist,but a good coordination between the emission trading and the renewable energy subsidy can achieve better emission reduction outcomes.

关键词： Dynamic simulation Energy conservation Emission reduction Emission trading Renewable energy Policy effectiveness

Wind speed equalization-based incoming wind classification by aggregating DFIGs

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Journal of Modern power Systems and Clean Energy 2013年第1期1卷 42-48页

作者： Zhaojun MENG Feng XUE Xueming LI Group Corporation(state grid electric power research Institute) Nanjing 210003JiangsuChina

With the development of wind energy,it is necessary to develop equivalent models to represent dynamic behaviors of wind farms in power *** equivalent wind method is investigated for the aggregation of doubly-fed induction generator wind *** detailed procedures for the calculation of equivalent wind are *** necessity of classifying incoming winds is *** improve the performances of the method,incoming winds are classified according to mean wind speeds and positive/negative semi-variances of wind speeds,and a group of turbines with similar incoming winds are aggregated *** effectiveness of the method is verified through simulations in MATLAB/Simulink.

关键词： DFIG power curve Equivalent wind Aggregated wind turbine

Audible Noise Performance of High Voltage AC Conductor Bundles at an Altitude of 226lm

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CSEE Journal of power and Energy Systems 2023年第6期9卷 2447-2455页

作者： Wangling He Baoquan Wan Shilong Huang Yunpeng Liu Jiangong Zhang Xiao Han North China electric power University Baoding 071000China China electric power research Institute(state Key Laboratory of power grid Environmental Protection) Wuhan 430074China

Extra or ultra-high voltage transmission lines can exhibit strong corona discharge and generate severe audible noise(AN)at high altitudes,which has become a critical limiting factor for power lines ***,the AN data of bundle conductors at high altitudes are very rare,which cannot adequately support the power utilities to make reasonable conductor *** this paper,a sound pressure level(SPL)of 14 types of bundle conductors is investigated by using an ultra-high-voltage(UHV)corona cage(8 m×8 m×35 m)at an altitude of 2216 m,where the bundle numbers between 4 and 12 and the conductor types are used in 500 kV,750 kV or 1000 kV power transmission *** a large number of valuable AN data are obtained;the influences of bundle numbers and sub-conductor diameters on an acoustic power density level(LPWL)are analyzed;and an A-weighted LPWL calculation method is *** addition,by comparing the AN data obtained from the low-altitude area(altitude:23 m),the AN altitude correction factor is concluded,and the influences of conductor parameters and the surface electric field strength on correction factors are *** results obtained in this paper can provide important data for the construction of high-altitude AC power lines.

关键词： AC power lines audible noise corona discharge high altitude

Pathway Planning of Nuclear power Development Incorporating Assessment of Nuclear Event Risk

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Journal of Modern power Systems and Clean Energy 2024年第2期12卷 500-513页

作者： Xinxin Yang Yusheng Xue Bin Cai School of electrical Engineering Southeast UniversityNanjingChinaand they are also with State Grid Electric Power Research Institute(NARI Group Corporation)NanjingChina state Key Laboratory of Smart grid Protection and Operation Control NanjingChina state grid electric power research Institute(NARI Group Corporation) NanjingChina

The nuclear event risk(NER)is an important and disputed factor that should be reasonably considered when planning the pathway of nuclear power development(NPD)to assess the benefits and risks of developing nuclear power more *** paper aims to explore the impact of nuclear events on NPD pathway *** influence of nuclear events is quantified as a monetary risk component,and an optimization model that incorporates the NER in the objective function is *** optimize the pathway of NPD in the lowcarbon transition course of power supply structure evolution,a simulation model is built to deduce alternative NPD pathways and corresponding power supply evolution scenarios under the constraint of an exogenously assigned carbon emission pathway(CEP);moreover,a method is proposed to describe the CEP by superimposing the maximum carbon emission space and each carbon emission reduction(CER)component,and various CER components are clustered considering the emission reduction characteristics and resource endowments of different power generation technologies.A case study is conducted to explore the impact of NER and its risk valuation uncertainty on NPD pathway *** method presented in this paper allows the impact of nuclear events on NPD pathway planning to be quantified and improves the level of coordinated optimization of benefits and risks.

关键词： Low-carbon transition power supply structure evolution nuclear power development(NPD) quantitative analysis nuclear event risk evaluation

Self-sensing active magnetic bearing using real-time duty cycle

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Journal of Zhejiang University-Science C(Computers and Electronics) 2013年第8期14卷 600-611页

作者： Ming TANG Chang-sheng ZHU Jie YU state grid Sichuan electric power research Institute College of electrical Engineering Zhejiang University

In a self-sensing active magnetic bearing (AMB) system driven by pulse width modulation (PWM) switching power amplifiers, the rotor position information can be extracted from coil current and voltage signals by a specific signal demodulation process. In this study, to reduce the complexity of hardware, the coil voltage signal was not filtered but measured in the form of a duty cycle by the eCAP port of DSP (TMS320F28335). A mathematical model was established to provide the relationship between rotor position, current ripple, and duty cycle. Theoretical analysis of the amplitude-frequency characteristic of the coil current at the switching frequency was presented using Fourier series, Jacobi-Anger identity, and Bessel function. Experimental results showed that the time-varying duty cycle causes infinite side frequencies around the switching frequency. The side frequency interval depends on the varying frequency of the duty cycle. Rotor position can be calculated by measuring the duty cycle and demodulating the coil current ripple. With this self-sensing strategy, the rotor system supported by AMBs can steadily rotate at a speed of 3000 r/min.

关键词： Self-sensing Active magnetic bearing (AMB) Frequency spectrum characteristic

A novel fragile watermarking scheme for image tamper detection and recovery

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Chinese Optics Letters 2010年第7期8卷 661-665页

作者：朱少敏刘建明 China electric power research Institute state grid Information & Telecommunication Co. Ltd.

We propose a fragile watermarking scheme capable of image tamper wise dependency mechanism. Initially, the image is divided into detection and recovery with a block blocks with size improve image tamper localization precision. By combining image local properties of 2~2 in order to with human visual system, authentication data are acquired. By computing the class membership degree of each image block property, data are generated by applying k-mean clustering technique to cluster all image blocks. The recovery data are composed of average intensity obtained by truncating the two least significant bits （LSBs） of each pixel within each block. Finally, the logistic chaotic encrypted feature watermark consisting of 2-bit authentication data and 6-bit recovery data of image block is embedded into the two LSBs of each pixel within its corresponding mapping block. Experimental results show that the proposed algorithm does not only achieve superior tamper detection and locate tiny tampered positions in images accurately, it also recovers tampered regions effectively.

关键词： Authentication Cluster computing Clustering algorithms Image processing Pixels Recovery Watermarking

Intelligent Breakage Assessment of Composite Insulators on Overhead Transmission Lines by Ellipse Detection Based on IRHT

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CSEE Journal of power and Energy Systems 2023年第5期9卷 1942-1949页

作者： Zhikang Yuan Linxuan He Shaohe Wang Youping Tu Zhaojing Li Cong Wang Fan Li College of Electronic and Information Engineering Tongji UniversityShanghai 201804China the state Key Laboratory of Alternate electrical power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China state grid Zhejiang electric power research Institute Hangzhou 310014China state grid Jiangxi electric power research Institute Nanchang 330000China

With the development of unmanned aerial vehicle(UAV)technology,visible images are playing an important role in the maintenance of power *** achieve the shed breakage evaluation of composite insulators by UAV visible images,an intelligent fault assessment method is ***,the composite insulators in visible light images are identified by *** image preprocessing,the image is enhanced and the noise is ***,a canny operator is used to extract the edge of the *** Improved Randomized Hough Transform(IRHT)is used to detect the ellipses in the edge *** parameters of the detected ellipse,length of major axes and minor axes,center coordinates and deflection angle of major axes,are used to realize the segmentation of the composite ***,the number of pixel points in the ellipse and the distance between the points and the ellipse boundary are used to judge whether there are breakage or cracks on the *** area ratio of the breakage to the whole shed is calculated based on the number of pixel points inside the broken *** method can be realized without a large amount of training dataset of the specific fault type and provides a technical basis for the online fault assessment of a composite insulator on overhead transmission lines.

关键词： Breakage assessment composite insulator ellipse detection Improved Randomized Hough Transform(IRHT)

Low frequency oscillation characteristics of East China power grid after commissioning of Huai-Hu ultra-high voltage alternating current project

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Journal of Modern power Systems and Clean Energy 2015年第3期3卷 332-340页

作者： Chao WANG Yang LV Hongyang HUANG Jing ZHANG Jihong LI Yingyi LI Weizhen SUN Yong CHANG state grid Zhejiang electric power Company Hangzhou 310007China state grid Jilin electric power Company Changchun 130000China state grid Operation Company Beijing 100052China

The low frequency oscillation characteristics of East China power grid after commissioning of the first ultra-high voltage alternating current(UHVAC)project-the Huai-Hu UHVAC project are *** low frequency oscillation cases occurred in East China power grid in the past few years are reviewed and *** on the analysis of the different typical operation modes,the main low frequency oscillation modes in East China power grid in the early stages of development of ultra-high voltage(UHV)are summarized,and the impacts of the significant power grid maintenance on low frequency oscillation characteristics are ***,the oscillation mode of UHV generators to East China power grid is researched,and the importance of the power system stabilizator(PSS)is ***,the comparative analysis between the time domain and the frequency domain is carried out,and the influences of the governing system on low frequency oscillation characteristics are ***,both the focus and the direction of low frequency oscillation research are presented.

关键词： Ultra-high voltage(UHV) Low frequency oscillation Forced oscillation power system stabilizator(PSS) Governing system