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Sun Q.,Hunan University | Yao J.,Hunan University | Zhao J.,Hunan Electric Power Company | Jin M.,Hunan University | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

An accurate short-term bus load forecasting is the basis of realizing energy saving, consumption reducing and meticulous management of dispatching. The integrated forecasting method presented was based on the selection of optimal similar days, using improved clustering analysis algorithm to obtain characteristic curves and sets of historical per-unit curves with similar shape. Identifying bad data and making adjustments by constructing vertical and horizontal eigenvectors reflecting the properties of the sample points. In order to obtain a set of curves whose load level is similar to the target date, the effects of daily characteristics factors on the load level was calculated, and fuzzy object function is weighted over each factor importance degree. Establishing discriminant function of all sets with similar shape, and target date was classified. Taking the intersection of load level set and curve shape set as the result of similar day selection. Sample with minimum date interval to target date was selected as virtual predict object, and then the weight of each algorithm in integrated forecasting was calculated. Case study shows that the proposed method can be effective in improving the quality of raw data, as well as the bus load forecasting accuracy. © 2013 Chinese Society for Electrical Engineering.

Peng J.-C.,Hunan University | He Y.-Q.,Hunan University | Zhou Z.-M.,Hunan Electric Power Company | Jiang H.,Hunan University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

A fast evaluating method on distribution system reliability is proposed, aiming at the distribution system with the main supply and an alternative supply. In this method, the distribution system is divided into main and branch networks. At first, the up-stream reliability indices of each point in branch networks are determined by up-stream delivering of each comoponent's reliability indices. Each branch network is replaced by an equivalent component in the main network. Then the failure-mode-effect-analysis (FMEA) method is employed to calculate the reliability indices of each point in the main-network, and the down-stream reliability indices of each point in the branch-network. Then the down-stream reliability indices of each point is determined by down-stream merging of reliability indices of the up-stream-network. Synthesizing the up-and down-stream reliability indices yielded the reliability indices of each point in branch-neworks. The proposed method takes into account the difference in operation time of breakers and section switches. It is not only as accurate as the FMEA method, but faster than the existing algorithms. Simulation results have verified the effectiveness of the proposed novel algorithm. © 2010 Chin. Soc. for Elec. Eng.

Lu Z.,Huazhong University of Science and Technology | Zhao M.,Huazhong University of Science and Technology | Xie P.,Hunan Electric Power Company | Wu L.,Huazhong University of Science and Technology | And 3 more authors.
Journal of Lightwave Technology | Year: 2012

In the last few years, much attention has been paid to the researches of metallic helical metamaterials due to their giant circular dichroism for transmitted lights. However, so far as we know, there is little work concerning the study of their reflection properties, which are also significant questions for the helical metamaterials. In this work, we study the reflection properties of the helical metamaterials by using the Finite-Difference Time-Domain (FDTD) method. The circular dichroism and the reflected polarization states of left-handed single-, double-, triple-, and quadruple-helical structures are investigated, respectively. It's found that both the single-and the double-helical structures perform giant circular dichroism, and their reflected polarization states are related to the handedness of helical structure; while triple-and quadruple-helical structures exhibit no circular dichroism at all, and their reflected polarization states are irrelevant to the handedness of helical structure. © 2012 IEEE.

Wang Z.,Nanchang Institute of Technology | Su H.,Hunan Electric Power Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

In order to improve the adaptability and reliability for evaluation of the investment value of power plant carbon capture systems, a decision-making mathematical model for carbon-capture system optimal investment timing is proposed based on the real option theory by referring to the real option characteristics of venture capital investment for carbon capture systems. By taking into account the irreversibility and delay ability of investment decisions, and the uncertainties of carbon price and carbon mitigation cost, the investment critical value and the optimal investment strategy for power plant carbon capture systems are obtained. The results of numerical example reveal that the model can make a rational assessment for the opportunity cost of venture capital investment, and the potential value of the project can be exploited as much as possible. Compared with the traditional net present value assessment method, the proposed model can overcome the defects of the net present value method, and effectively guide the timing of carbon capture system risk investment, rather than make the simple decision on immediate investment or nondevelopment. The model has provided a quantitatively analytic mathematical tool for the investment carbon capture system in a power plant that can be used as scientific reference for decision-makers. © 2014 State Grid Electric Power Research Institute Press

Li C.,Huazhong University of Science and Technology | Li H.,Zhongnan University of Economics and Law | Kou P.,Hunan Electric Power Company
Neurocomputing | Year: 2014

Heuristic optimization has shown its superiority in handling identification problem of complicated system, for methods based on heuristic optimization do not have special requirements on model structures of the target system. In this paper, a piecewise function based gravitational search algorithm (PFGSA) is proposed and applied in parameter identification of automatic voltage regulator (AVR) system. In the proposed algorithm, a piecewise function is designed as the gravitational constant function to replace the traditional exponential equation. The piecewise function provides more rational gravitational constant to control the convergence of algorithm, and thus excellent searching ability is likely to be achieved. Moreover a new weighted objective function is proposed in the identification frame. Comparative experimental studies are conducted to test the searching ability of PFGSA and to verify the performance of proposed identification strategy, while genetic algorithm, particle swarm optimization and GSA are employed for comparison. The experimental results show that PFGSA performs the best on term of accuracy and stability in the parameter identification of AVR system, and the proposed identification strategy is effective. © 2013 Elsevier B.V.

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