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Study on cascaded SSSC small-step ( less than or equal 2 μs) modeling in RTDS

Gaodianya Jishu/High Voltage Engineering 2006年第10期32卷 72-75+90页

作者： Jiang, Xu Xiao, Xiangning Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

Static Synchronous Series Compensator (SSSC) is a sort of FACTS equipments based on the series Voltage Source Converter (VSC). The small-step ( less than or equal 2 μs) model of SSSC is built in RTDS in this paper. The main circuit structure of SSSC consists of cascaded H-bridge units and single-phase coupling transformer. Because of the simple and independent connection among three phases, it is easy to present the unbalanced compensation. The modulation strategy of SSSC which adopts staircase modulation can be got on-line;it uses equal area principle to calculate the trigger angels in this way. Constant impedance strategy is also applied, namely the output voltage of SSSC is proportional to the line current in amplitude and leads or lags the line current by π/2. Details for building cascaded multilevel SSSC model in RTDS are shown in this paper;in addition, there are also some tips about how to present the small-step simulation of VSC. Firstly, the VSC module must be arranged suitably on the allowable simulation scale. Secondly, the special transformer has to be used at the interface between large step model and small step one. Thirdly, in order to avoid the 'stiff' instance of the interface, the VSC breaker must substitute for the large step side breaker. Finally, the division module must be set properly in that the dividend may equal to zero. Moreover, the results including indices such as P, Q, current of line, modulation index and output voltage under different running conditions have proved that the model in RTDS is almost perfect by comparing with the results got in EMTDC/PSCAD4.02.

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Study on Xiluodu and Xiangjiaba UHVDC Earth Electrodes

Study on Xiluodu and Xiangjiaba UHVDC Earth Electrodes

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International Conference on power system Technology (powerCON)

作者： Mingde Cui Lianguang Liu Zhongming Sun Key Laboratory of Power System Protection andDynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China Beijing Wanglian HVDC Engineering Technology Company Limited Beijing China

Grounding characteristics of linear, star-type and toroidal electrodes are discussed in this paper. Based on the analysis of the performance of double-ring in uniform and horizontal two-layer soils, an electrode model of standard triple concentric rings buried with different depth is presented for plusmn800 kV Xiluodu and Xiangjiaba converter stations in the first period of Jinsha River DC projects. Considering the three sending converter stations in the projects close to each other relatively, an initial analysis of sharing electrodes has been made, including the operation mode of converter stations, choice of rated current and the design model of electrodes. Simulation results obtained from the electrode sites primarily selected for Xiluodu right-bank converter station show that the above model can satisfy the operation requirements with a better economical performance and sharing electrodes by multi-converter stations is also feasible. They may supply some reference to the practical projects.

关键词： Earth Electrodes Grounding Rivers Soil control systems Sun Hydroelectric power generation Geology Performance analysis

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Long-Term Electricity Purchase Allocation Strategy and Risk Evaluation in power Markets

Long-Term Electricity Purchase Allocation Strategy and Risk ...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Ming Zhou Gengyin Li Yixin Ni Key Laboratory of Power SystemProtection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong China

This paper presents an integrated framework for the optimal management of electric energy purchase allocation and risk evaluation for load service entities (LSEs). We propose the framework of power portfolio of combined physical forward contracts and spot markets, which suggests that the forward contracts should have different on-peak and off-peak prices in accord with retail prices distinguishing on-peak and off-peak at the early stage of marketing operation of China electricity industry. The numerical results give the LSEs reasonable profits and risk hedging. The presented framework gives one possible and effective method for the optimal power portfolio and risk management in incomplete power markets

关键词： power markets Forward contracts Risk management Portfolios power generation Educational programs Investments Pricing power system protection power system security

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Research on Restraining Low Frequency Oscillation with Flywheel Energy Storage system

Research on Restraining Low Frequency Oscillation with Flywh...

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International Conference on power system Technology (powerCON)

作者： Yun Zhong Jiancheng Zhang Gengyin Li Zhiyuan Chen School of Information Engineering University of Nanchang Baoding Jiangxi China Department of Electrical power Engineering North China Electric Power University Baoding Hebei China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China Baoding Zhongli Power Science and Technology Development Company Limited Baoding Hebei China

Low frequency oscillations in the interconnected power systems are observed all around the world. Besides conventional PSS to suppress Low frequency oscillation, there are other modern FACTS devices to damp oscillation, among which flywheel energy storage system (FESS) is a comparative valid way. The theory on restraining low frequency oscillation used by flywheel energy storage system is described through transfer function diagram and complex torque coefficient. A numerical model of flywheel energy storage asynchronous motor controlled by VVVF inverter is derived from its mathematical model in alpha-beta coordinate system. Then the total model eigenvalue is analyzed. Based on analysis, attach control strategy using two parallel independent parts for active power control and reactive power control is designed in FESS to restrain low frequency oscillation. The calculation result shows that flywheel energy storage system is an effective way to restrain low frequency oscillation and enhance power system dynamic performance.

关键词： Frequency Flywheels Energy storage power system interconnection Transfer functions Torque Numerical models Inverters Mathematical model power system modeling

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Researches on high order harmonics interference and filters at DC side of UHVDC transmission system

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Gaodianya Jishu/High Voltage Engineering 2006年第12期32卷 174-177页

作者： Zheng, Jin Wen, Jun Shi, Yan Han, Minxiao Yan, Jinchun Beijing Wanglian HVDC Engineering Technology Co. Ltd. Beijing 100088 China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

The communication of power line carrier (PLC) in the frequency of 20-500 kHz in the ultra-high voltage direct current (UHVDC) transmission line with ±800 V rated voltage and the radio communication range from 500 kHz-20 MHz near the converter substation and along the ultra-high voltage direct current transmission line are interfered strongly by high order harmonics from converters and direct current transmission line and neutral line of ultra-high voltage direct current transmission system. It's a virtual way to reduce power line carrier interference (PLCI) and radio interference (RI) to install PLC/RI filters at the terminals of the polar line and neutral line at the direct current side of converter substation. The power line carrier interference and radio interference from the ultrahigh voltage direct current transmission system with two series of 12 pulse converters in a pole line are produced by the chopping of valve voltage of converters and the discharging of electric corona and insulators. The limitation values for power line carrier interference and radio interference from the converter substation of ultra-high voltage direct current transmission system are analyzed in the paper. After calculating the total power line carrier interference and radio interference at the terminal of the direct current pole line and neutral line in the circumstance of PLC/RI filter schemes with a harmonic analysis program, a economical and practical PLC/RI filter scheme for limiting power line carrier interference and radio interference at the direct current side of ultra-high voltage direct current converter substation is produced.

关键词： Communication Filters Harmonics power Line Carrier (PLC) Radio Interference (RI) UHVDC transmission

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power system Transient Stability Simulation Using the Precise Time-Integration Method

Power System Transient Stability Simulation Using the Precis...

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International Conference on power system Technology (powerCON)

作者： Xianrong Chang Yubin Wang Lifeng Hu School of Electrical Engineering North China Electric Power University Baoding Hebei China Power Supply Bureau of Shijiazhong Hebei China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education(North China Electric Power University) and School of Electrical Engineering North China Electric Power University Baoding 071003 Hebei Province P. R. China. e-mail: HLF873@***

Based on the precise time-integration method and the models of power system, a fast and simple simulation method for power system transient stability is discussed in this paper. This method has its advantages such as the numerical stability and programming simplicity. The techniques of factorization and sparse matrix are used in this method. The computer simulations on a real-life system prove the effectiveness of this method.

关键词： power system transients power system stability power system simulation power system modeling power system reliability Numerical stability power system protection power system dynamics power system security power system analysis computing

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Novel decentralized approach through optimal resource allocation for congestion management

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2006年第22期26卷 46-53页

作者： Liu, Kai Zhao, Da-Pu Hou, Yun-He Bi, Tian-Shu Ni, Yi-Xin Wu, Felix Department of Electrical and Electronic Engineering University of Hong Kong Hong Kong Hong Kong Department of Electric Engineering Tsinghua University Beijing 100084 China Key Power System Lab. Shenzhen Research Institute Shenzhen 518055 China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The available capacities of possible congested transmission lines are considered as commonly shared resources for bilateral and multilateral transactions in the market. Each transaction maximizes its profit using limited capacity of transmission line allocated by the ISO. Through the proposed decentralized optimization algorithms, the ISO searches the optimal allocation of the capacities of congested transmission lines to the individual transactions and finally the same market efficiency (social welfare) as centralized optimization is achieved. This decentralized approach is more suitable for power market environment since it does not require private and sensitive information submission from individual transactions to the ISO and the resource allocation decision is always feasible during iterations. The mathematical model, calculation procedure and relevant proof are presented. The computer test results from the IEEE 30 bus system show clearly the effectiveness of the approach and its consistency with the centralized optimization.

关键词： Resource allocation

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Research on DC bias due to magnetic storm and DC transmission

Research on DC bias due to magnetic storm and DC transmissio...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Shi, Weiping Liu, Lianguang Wang, Qian Liu, Zongqi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing 102206

ISBN: (纸本)0780391144

This paper focuses on the research on the DC bias due to magnetic storm and HVDC. In the paper, we introduce the DC bias problem of Jiangsu Yang-Huai transmit electric system and Southern power Grids, discuss the harmful effect of the transformer DC bias and the significance of research, and analyze the compensation, weakening and elimination of transformer bias current. Finally, the problems that should be paid attention to and some corresponding suggestions are proposed. © 2005 IEEE.

关键词： HVDC power transmission

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Parallel operation of hybrid active power filter with passive power filter or capacitors

Parallel operation of hybrid active power filter with passiv...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Xu, Yonghai Xiao, Xiangning Liu, Hao Wang, Hong Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China

ISBN: (纸本)0780391144

Harmonic pollution and reactive power compensation are the important power quality problems. This paper proposes a combined power filter system consisting of the parallel operation of a hybrid active power filter (HAPF) and the passive power filters or capacitors. The HAPF is formed by a single tuned LC filter per phase and a small-rated three-phase active filter, which are directly connected in series. The characteristics of the combined system and the harmonic current detection method using the combination of load current and the mains current are analyzed and simulated. The simulation results show that good filter performance can be obtained by the combined system. Experimental results from a 100kVA/380V hardware prototype parallel operation with capacitors are presented to conform the validity and effectiveness of the combined system. © 2005 IEEE.

关键词： Active filters

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Multiobjective optimization scheduling based on fuzzy genetic algorithm in cascaded hydroelectric stations

Multiobjective optimization scheduling based on fuzzy geneti...

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2005 IEEE/PES Transmission and Distribution Conference and Exhibition: Asia and Pacific

作者： Hu, Guoqiang He, Renmu Ma, Rui Wang, Peng Yang, Huachun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China

ISBN: (纸本)0780391144

The multi-objective fuzzy optimal method based on the fuzzified optimal solutions of single objectives need not list all non-inferior solution sets, which can optimize directly objectives in value area of variables. This method can reflect the interrelation between individual objective optimal solutions and multi-objective optimal solution. On the basis of fundamental principle of multi-objective fuzzy optimization and genetic algorithm, combing with the concept of objective relative subject degree, this paper presents a multi-objective optimization approach for the hydroelectric power system with contradictory objectives. The proposal method considers the satisfied degree of various characters and contradictory objectives and seeks an appropriate optimized solution to make each objective optimal as possible considering each objective comprehensively. The simulation results of example show that the fuzzy genetic algorithm is an effective method for multi-objective optimization problem in the cascaded hydroelectric plants. © 2005 IEEE.

关键词： Hydroelectric power plants

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