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Su H.,Xiangtan Power Supply Bureau | Li R.,Guangxi University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In order to solve the problem that the multi-objective transmission network planning under smart grid condition, under smart grid infrastructure, the investment cost of the planning schemes was applied to weight economic performance, the outage loss of customers was applied to measure the reliability of the schemes, available transfer capability of the network was applied to evaluate the flexibility of the schemes, the method of using the system expansion factor was applied to quantify the adaptability of the schemes, and the lowest limit value of the line betweenness was applied to assess the invulnerability of the scheme. On this basis, a multi-objective transmission network planning model based on cosine prioritizing theory was established. The entropy theory was introduced to determine the weight coefficients of indices and the value of weight could avoid to be judged by subjectivity. In the high-dimensional space, by comparing the cosine value between directed line segment in each scheme and ideal directed line segment in ideal scheme, the optimum scheme was obtained, so that it gives effective guidance for the future smart grid planning and construction. Analysis of an example verified the validity and feasibility of the method. © 2012 Chin. Soc. for Elec. Eng. Source


Xu H.-J.,Nanchang Institute of Technology | Wang Z.-Y.,Nanchang Institute of Technology | Su H.-Y.,Xiangtan Power Supply Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

In order to solve the problem of randomness and fuzziness in power transformer fault diagnosis, a new fault diagnosis method for power transformer based on feedback cloud entropy model is proposed. After the statistic analysis of the collected fault examples of chromatographic data for transformer oil, which is put into Bayesian feedback backward cloud generator as cloud drop, the transformer fault diagnosis standard normal cloud model is built based on parameter values of fault characteristic gases cloud model. The model integrates cloud correlation coefficient and information entropy theory, reduces the dependence on the single standard normal cloud model and digs more information of the dissolved gases in transformer oil, and improves the accuracy of transformer fault diagnosis. By increasing training samples and correction cloud model parameter, the effectiveness of the model can be further enhanced. The results of example show that the model has higher accuracy, and has well theoretical value and application prospects. Source


Xia F.,Nanchang Institute of Technology | Fan L.,Nanchang Institute of Technology | Su H.-Y.,Xiangtan Power Supply Bureau | Li R.-Q.,Guangxi University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

Aiming at the characteristics of the integration evaluation of power quality, the weights of indexes in power quality synthetic evaluation are obtained by integrating the analytic hierarchy process method, the entropy method and the mean square difference method. Given a full consideration to the fuzziness and randomness of the boundary value of power quality classification levels, combining the characteristic of uncertain reasoning of the cloud model and the advantage of qualitative and quantitative analysis of the matter element analysis theory, a comprehensive power quality evaluation model is proposed based on cloud matter element analysis theory. By establishing the standard cloud matter element model of power quality comprehensive evaluation and calculating the association degree between the matter element to be evaluated and standard cloud matter element model, the coefficient of credible degree is defined, which allows the model not only obtains the level of power quality but also provides the credibility information of the evaluation result. The superiority and effectiveness of the model is demonstrated by results of actual numerical example. Source


Su H.-Y.,Xiangtan Power Supply Bureau | Li R.-Q.,Guangxi University | Tang L.-Q.,Guangxi University | Wang W.-Z.,Guangxi University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

The index system fitting for integrated assessment for electrified railway power quality is analyzed, according to the electrified railway traction load's characteristics of nonlinearity, asymmetry, and random time-varying, etc. Using the standard pattern sequence of electrified railway power quality level limits, power quality standard samples are constructed. A new method for determining the weight coefficient is proposed, which takes the minimum of square sum of standard samples evaluation error as the objective function and the characteristics of the weight information as constraints. Grey target theory is introduced into the comprehensive assessment of power quality, and the electrified railway power quality level is obtained by constructing power quality standard mode, applying gray target transformation, establishing gray correlation with difference information space, and calculating grey bull's-eye coefficient and grey bull's-eye degree. Practical examples show that the method can obtain comprehensive assessment of power quality for electrified railway objectively and rationally, demonstrating the model is effective and superior. Source


Wang Z.-Y.,Nanchang Institute of Technology | Fan L.,Nanchang Institute of Technology | Su H.-Y.,Xiangtan Power Supply Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

According to the interval number concept of assessment standard of power quality, a new synthetic power quality evaluation model based on interval number theory is proposed. Based on the original indexes weight range, the subjective weighting is obtained using the linear goal programming model, and the objective weighting is obtained using the improved scatter degree, then the comprehensive weighting could be determined based on addition principle. On this basis, a multiple objective decision-making ideal interval method is introduced to calculate the distance between indexes data of the sample and ideal interval. The approach degree between the sample data and power quality standard mode is defined by using the normalized reciprocal of the distance, thus the comprehensive evaluation of power quality is achieved. This method not only can perform comprehensive assessment, but also can evaluate power quality difference more precisely within the same power quality grade. The feasibility and validity of the proposed model are demonstrated with the results of the practical example. Source

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