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Liu Y.,Shanghai JiaoTong University | Sheng G.,Shanghai JiaoTong University | Sun X.,Liaocheng Electrical Power Company | Gao S.,Shandong EHV Power Transmission Company | Jiang X.,Shanghai JiaoTong University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

The relationship between the transmission line length and the operating states of transmission line, including the conductor temperature, equivalent icing thickness and wind speed, is analyzed based on the equation of state in transmission line. The corresponding method to calculate the transmission line length is also proposed by considering the operating states of transmission line. Correctness of this method is verified by the conductor tension and conductor temperature practical running data from Northeast China. Finally, the conversion equation is established according to relationship between the transmission line length and the operating states of transmission line, and then the actual distance to fault position is converted into the horizontal distance. © 2012 State Grid Electric Power Research Institute Press. Source


He Z.M.,Shanghai University of Engineering Science | Liu Y.D.,Shanghai JiaoTong University | Shen W.,Shanghai JiaoTong University | Sun X.R.,Liaocheng Electrical Power Company | And 3 more authors.
Applied Mechanics and Materials | Year: 2014

In order to improve the economy of operation of transformer, this study presents a strategy to ensure the safety of power transformer for the situation of overload operation of parallel transformer. According to the variation of actual transformer operation, the authors divide the daily load curve into two typical time periods. In the high load operation period, except the constraint of minimum power loss for the economic operation, the factor for hot-spot temperature rise of the transformer should also be considered, so that an economic operation mode and parallel switching time could be obtained. This strategy estimates the hot spot temperature by the finite difference method, and obtains the optimal switching time through binary searching, according to the environment temperature and load curve. The analysis of the example of the operation of two sets of three winding transformers in parallel with different capacity shows that the method of optimization of the operation could reduce the loss. In the meantime, it could ensure the operation safety of the transformer, and prolong the service life of transformer. © (2014) Trans Tech Publications, Switzerland. Source


Zhang F.,Shandong University | Liang J.,Shandong University | Li J.,Liaocheng Electrical Power Company | Gao H.,Binzhou Electrical Power Corporation | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

A novel single ended fault location algorithm based on the initial reverse polarity traveling wave (RPTW) detection is proposed. Research shows that the RPTW has less influencing factors, which ensures the high detection reliability, moreover, the time when the RPTW arrives has a certain relationship with fault location, has a piecewise linear characteristic. According to the characteristics of RPTW and combining the initial traveling wave, the fault section and the primary fault location can be determined as soon as the initial RPTW can be identified. After that the exact fault point will be located using other fault information contained in the single ended traveling waves. Only the initial traveling wave and initial PRTW have been used in the present algorithm, which will guarantee the detection accuracy. Simulation results show that the proposed algorithm can effectively locate the fault point, and obviously improve the single ended fault location's reliability and accuracy. © 2013 State Grid Electric Power Research Institute Press. Source


Liu Y.,Shanghai JiaoTong University | Sheng G.,Shanghai JiaoTong University | Sun Y.,Liaocheng Electrical Power Company | Liang J.,Xian Electrical Engineering Co. | Jiang X.,Shanghai JiaoTong University
Dianwang Jishu/Power System Technology | Year: 2012

On the basis of analyzing characteristic of fault current in overhead transmission line, a method to comprehensively judge the fault zone by utilizing deviation degree among zero-sequence components of the fault current measured at different detecting points and the energy of the first traveling wave of the fault current is proposed. Corresponding relationships among the measured traveling wave of the fault current and its reflected and refracted waves obtained by fault detector installed at different positions are analyzed, and the number of detecting points needed by the distributed fault location system for single-phase ground fault and the installation positions of detectors are put forward. Finally, according to the fault zone corresponding fault location equation is chosen to determine the position of fault point. Simulation results show that by use of the proposed fault location method a more accurate result of fault location can be attained. Source


Liu Y.,Shanghai JiaoTong University | Sheng G.,Shanghai JiaoTong University | Shen X.,Shanghai JiaoTong University | Jiang X.,Shanghai JiaoTong University | And 3 more authors.
Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012 | Year: 2012

This paper delineates a novel analytical and computational approach to fault location for power transmission grids. The distributed fault location methodology involves three locators installed along the line. The fault section methodology is proposed using the deviation between the fault currents at different detection points and the energy of the first traveling wave head of fault current. The required positions of locators are analyzed according to the relationship between the detected traveling wave and its reflected and refracted waves. The location equation is established by the fault section. PSCAD Simulation experiment indicates that this distributed fault location method has good application value. © 2012 IEEE. Source

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