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Wang H.,Wuhan University | Hu Z.,Wuhan University | Zhang Y.,Guangxi Electric Power Research Institute | Li C.,Wuhan University | And 2 more authors.
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2014

This paper introduces a combination forecasting model which is based on ensemble empirical mode decomposition and least squares support vector machines(LSSVM) into forecasting short-term wind speed, in the view of excavating the nonstationarity and nonlinearity of wind series. Firstly, wind series are decomposed into a group of relatively stable subsequence by ensemble empirical mode decomposition to reduce mutual influences among diverse trend information. Secondly, build forecasting models respectively for each subsequence adopting least squares support vector machines. Adaptive disturbance particle swarm optimization and model learning feedback mechanism is used to jointly optimize the dimension of the learning sample input and the hyper parameters of LSSVM forecasting model to lower the predicting risk. Finally, the predicting results of each subsequence are superposed to obtain wind speed forecasting results. The case study shows that the proposed combination forecasting model is able to excavate wind series features effectively and has relatively high predicting accuracy.

Song G.-B.,Xi'an Jiaotong University | Cai X.-L.,Xi'an Jiaotong University | Gao S.-P.,Xi'an Jiaotong University | Suonan J.-L.,Xi'an Jiaotong University | Yang Z.-L.,Xinxiang Power Supply Company
Gaodianya Jishu/High Voltage Engineering | Year: 2011

The natural frequency signal of DC lines is more obvious than that of AC lines. Combining the system structure, it is found that the natural frequency of VSC-HVDC is related with line length. Theoretically, the natural frequency differential is zero for external fault and it is a huge value for the internal fault. Accordingly, a new pilot protection principle and its primary criterion for HVDC transmission line are proposed based on current spectrum analysis at both ends. For the dead zone at the midpoint of the line, a secondary criterion is proposed. At the same time, the system of VSC-HVDC is built in PSCAD and various faults are simulated. In the protection principle, only current information of both converters are used and synchronization is not needed for the transmission of natural frequency. The simulation results show that the protection principle can identify the faults reliably and rapidly in different conditions, and is not affected by the fault resistance.

Du G.,Kaifeng Power Supply Company | Liu X.,Kaifeng Power Supply Company | Su G.-F.,Xinxiang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

Due to the large amount of branches and high grounding resistance of distribution grid, the single-phase-to-earth fault location has not been solved effectively. The single-phase-to-earth fault location technology is proposed by combining FTU and "S" signal injection method. Firstly, the zero-sequence voltage and zero-sequence current are measured by using line FTU so that the fault area is located. Then the "S" signal is injected, and the signal can be measured by electromagnetic induction theory so as to find the exact location of grounding fault. To avoid the influence of distributed capacitance to "S" injection signal, the calculation method of length of FTU isolation area is intensively studied. Moreover, the on-line location is possible by using this method. The correctness and feasibility of this technology have been fully proved by site experiments.

Shi Y.,Henan Normal University | Wang M.,Henan Normal University | Shen M.,Xinxiang Power Supply Company
Journal of Petroleum Science and Engineering | Year: 2016

Measurement of oil-water flow parameters is of great importance in petroleum industry. Due to its complicated flow structure, it is still a challenging problem. This paper presents the use of a multi-electrode conductance sensor and a dual-plane electrical resistance tomography (ERT) sensor to measure phase fraction and velocity in a horizontal oil-water flow. A series of experiments is carried out on a two-phase flow loop using mineral white oil and tap water. Taking advantage of different conductivity values of two fluids, the estimation of phase fraction is obtained by conductance measurements. By correlating voltage fluctuation signals measured from upstream and downstream sensor, the velocity of oil-water flow is evaluated. The phase fraction and velocity measured from two techniques are compared. Experimental results show that the multi-electrode conductance sensor is more suitable to estimate phase fraction of oil-water mixture. For the velocity measurement, cross correlation velocity obtained with multi-electrode conductance sensor is more closer to the mixture velocity of oil-water mixture. © 2016 Elsevier B.V.

Zhang Q.-Y.,Xinxiang Power Supply Company | Yue J.-F.,Taiyuan University of Technology
Conference Proceedings - 2012 IEEE 7th International Power Electronics and Motion Control Conference - ECCE Asia, IPEMC 2012 | Year: 2012

In order to improve the power quality and solve the problem of the low load capacity of 10kV distribution network, the paper analyzed the advantages of using 20 kV voltage grade in distribution network and described the present technical characteristics of distribution network in Zhengzhou. Meanwhile, a complete methodology of comprehensive evaluation of the voltage level sequence is introduced based on AHP. When the method is applied in Zhengzhou new district, through technical-economy comparison of the two voltage levels sequence based on the load density, obtained the conclusion of boosting medium voltage level and put forward the rationalization proposal and basis for the rational scheming of the voltage level in Zhengzhou New district and similar areas. © 2012 IEEE.

Wang Y.,Changsha University | Wang Y.,Xinxiang Power Supply Company | Zeng X.,Changsha University | Li R.,Changsha University | Liu Q.,Changsha University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

In view of the incapability of the traditional traveling wave fault location method for transmission lines of meeting the requirement on high precision location of the distribution network that is complex and profusely branching in structure, a new traveling wave fault location method based on multiple time information is proposed. The incidence matrix and distance matrix are built to judge the selection of fault. Based on the model for the location binary tree, the algorithm only uses time information and the structure of the distribution network to delete the ineffective arrival time of traveling wave and realize accurate fault location. EMTP simulation results show that the method has fairly high fault location precision and can meet the requirements of power network operation. © 2012 State Grid Electric Power Research Institute Press.

Li R.,Changsha University | Zeng X.,Changsha University | Li Z.,Changsha University | Wang Y.,Changsha University | Wang Y.,Xinxiang Power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

IEEE 1588 synchronous clock realized with TCP/IP is used for communication networks timing in substations. The path time-delay error of synchronous message is caused by the communication network transmission congestion. The precision error of IEEE 1588 clock synchronization is analyzed, and the correction methods of path time-delay error of synchronous message are proposed with the diffserv-based packets scheduling model. The bandwidth adjustment factor, pressing degrees mechanism and the time-delay of the synchronous message is determined through setting of network node service message priority. Then the correction methods of oscillation frequency of clock generator are presented. The IEEE 1588 synchronization clock error is thus corrected. Finally, the high precision network clock hardware platform is built. Experiment results show that the clock has the synchronization precision of nanosecond, and it can satisfy the time synchronization precision requirement of smart substations of IEC 61850 Std. © 2012 State Grid Electric Power Research Institute Press.

Zhang Y.M.,Henan mechanical and Electrical Engineering College | Ma X.,Xinxiang Power Supply Company
Applied Mechanics and Materials | Year: 2014

Through the research of the network flow measurement theory, we designed and implemented F-Monitor which is a network traffic monitoring system based on Linux platform. We use it protect the safety of the campus network. In this paper, we discuss the overall system architecture model, and elaborate the design and implementation of the system composed of packet capture module, data packet analysis module, the database module. In packet capture aspects, by the use of Linux platform in the system independent data packet capture library, based on the multi-mode traffic collection mechanism, we realize the data flow acquisition. In the data packet analysis, we based on the data flow analysis method to realize the data packet analysis. The module supports a variety of flow analysis, including TCP/IP, P2P, NetFlow and sFlow. In this paper, we describe the system database structure. © (2014) Trans Tech Publications, Switzerland.

Qin J.,Xinxiang Power Supply Company | Wang Z.,Xinxiang Power Supply Company
2012 2nd International Conference on Consumer Electronics, Communications and Networks, CECNet 2012 - Proceedings | Year: 2012

The cause and damage of earth potential interference are analyzed and studied in this paper, especially influence by nonuniform distribution of earth potential in power plant and transformer station, such as interference by impulse voltage caused by lightning current and big power frequency current, arc interference caused by earth short circuit in transformer station. On the basis of research on cause, approach and modus of interference, technology measures are proposed © 2012 IEEE.

Ke Z.,Xinxiang Power Supply Company
Applied Mechanics and Materials | Year: 2013

The smart grid is an ideal solution of the future electricity system, and scheduling aspects of the smart grid, the nerve center of the most intelligent can best embody the intelligent characteristic, this article summarizes the development of smart grid technologies, energy-saving scheduling, and the smart grid ofsignificance analysis to explore the implementation of energy-saving dispatch to the power industry, an energy efficient scheduling model and highlight the superiority of the energy-saving scheduling in order to ensure the smooth implementation of energy-saving scheduling. © (2013) Trans Tech Publications, Switzerland.

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