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Sun Y.,Shandong University | Li J.,Shandong University | Yin Z.,Beijing Electric Power Company
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

Quantifying the harmonic impacts of multiple harmonic sources is of great significance for the effective implementation of harmonic "rewards and punishment scheme". Based on the measured data, this paper proposed a new way to estimate the harmonic contributions of multiple harmonic feeders on the harmonic voltage of the point of common coupling (PCC) by using the M-estimation method and the partial least square regression method. Under harmonic frequencies, the mathematical model for the concentrated multiple harmonic sources system was constructed based on the Thevenin equivalent circuit. According to the relationships among all harmonic phasors, the "theory current" and "actual current" concepts were proposed, and their relationship was deeply analyzed. Furthermore, the harmonic impact index to estimate harmonic contribution of each harmonic feeder was proposed. Utilizing the above two currents, the harmonic impact was estimated based on M-estimation regression and partial least square regression method. The paper also analyzed the accuracy of M-estimation method and partial least square regression method. Results show that partial least square regression method has better performance, which is more suitable for practical application. © 2014 Chinese Society for Electrical Engineering. Source

Wang M.,North China Power Dispatch Center | Bao J.,North China Power Dispatch Center | Qi X.,Beijing Electric Power Company | Zhang Z.,North China Power Dispatch Center
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

Accurate power system parameters are the foundation to form a reliable power system model, which is essential for state estimation, power flow and contingency analysis, network losses analysis, stability analysis and protective relay setting calculation. Based on uniform transmission line equations and ∏-type equivalent circuit equations, and on the assumption that voltage phasors and current phasors at both ends of a transmission line are known, the methods to calculate transmission line distributed parameters and accurate ∏-type equivalent circuit parameters are given. Based on phasor measurement unit (PMU) measurements and statistical theory of normal distribution, an algorithm for on-line estimation of transmission line parameters is presented. Examples based on wide area measurement system (WAMS) in North China Power Grid show that the proposed methods are accurate and reliable. ©2010 State Grid Electric Power Research Institute Press. Source

Wu L.,North China Electrical Power University | Zhang J.,North China Electrical Power University | Liu R.,Beijing Electric Power Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

A reliability model of wind farm is proposed. The output of wind farm is considered to obey a joint probability distribution of available capacity and available wind energy. In this study, the wind farm is equivalent to a multi-state conventional unit by dispersing the output into several derating output levels. The model allows the simulation of wind farms containing either identical or different wind turbine types. The model can be easily used in the power system reliability assessment utilizing analytical or simulation methods to simplify the reliability assessment of power system containing large-scale wind farm. Finally, a case study is carried out on IEEE-RTS 79 test system to verify the effectiveness of the model. ©2012 State Grid Electric Power Research Institute Press. Source

Yu Y.,Tianjin University | Wang J.,Beijing Electric Power Company | Lv X.,Tianjin University
Science China Technological Sciences | Year: 2012

Concerning the integration of large-scale wind power, an integrated model of generation and transmission expansion planning is proposed based on the assessment of the value of steady state and dynamic security. In the assessment of security value, the unit commitment simulation based on the predicted hourly load and wind power output data in the planning horizon is used to evaluate the costs of preventive control, emergency control and social losses due to the uncertainty of load and wind power. The cost of preventive control consists of the fuel cost of power generation, the environmental cost and the load shedding cost. This not only provides a systematic method of security assessment of power system expansion planning schemes, but also broadens the perspective of power system planning from the technology and economic assessment to the measure of the whole social value. In the assessment process, the preventive control and emergency control of cascading failures are also presented, which provides a convincing tool for cascading failure analysis of planning schemes and makes the security assessment more comprehensive and reasonable. The proposed model and method have been demonstrated by the assessment of two power system planning schemes on the New England 10-genarator 39-bus System. The importance of considering the value of security and simulating hourly system operation for the planning horizon, in expansion planning of power system with integration of large-scale wind power, has been confirmed. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg. Source

Zhao Y.,North China Electrical Power University | Xue F.,North China Electrical Power University | Zhao X.,Beijing Electric Power Company | Guo T.,North China Electrical Power University | Li X.,North China Electrical Power University
Journal of Hazardous Materials | Year: 2013

A novel method has been developed to remove elemental mercury from simulated flue gas by a diperiodatonickelate (IV) solution. The influencing factors, such as diperiodatonickelate (IV) concentration, reaction temperature, solution pH, the initial Hg0 concentration, SO2 concentration and NO concentration were investigated at a bubbling reactor. In the presence of SO2 and NO, removal efficiency of 86.2% for elemental mercury was obtained. Meanwhile, 56.2% of NO and 98% of SO2 were simultaneously removed, under the optimal experimental conditions, in which diperiodatonickelate (IV) concentration was 6×10-3mol/L, reaction temperature was 50̊C, the initial Hg0 concentration was 20μg/m3 and pH was 8.5. Moreover, based on the research results of the hydrolyzing products of IO4-, and the analysis of the removal products of Hg0, the reaction mechanism of Hg0 removal was proposed. © 2013 . Source

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