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Zhang Y.,South China University of Technology | Shi H.,South China University of Technology | Zhai W.,South China University of Technology | He C.,Zhongshan Power Supply Bureau
Dianwang Jishu/Power System Technology

Using gray comprehensive relationship, the strong relation factors correlated with line loss are extracted, then a network line loss prediction model based on portfolio of GM (1, 1) and GM (1, N) is built. The variation of network loss rate is influenced by multi factors, thus the modeling parameters are optimally selected by following manner: through multi gray comprehensive relationship analysis the network loss data is preprocessed, then the weight-varying of judgment matrix is performed by analytic hierarchy process (AHP), finally the modeling parameters of GM (1, N) are optimally selected according to the comprehensive relationship of weighted combination. In combinatorial optimization firstly the GM (1, 1) model is used to pre-evaluate values of modeling parameters; then these values are substituted into GM (1, N) model to carry out accurate prediction of line loss rate. Results of calculation example show that for being naturally developed power network, the prediction performance of the proposed combinatorial model is stable and the prediction results are accurate. The proposed combinatorial model is suitable to medium-and long-term line loss rate prediction. Source

Zhang Y.,South China University of Technology | Liu H.,South China University of Technology | Jiang J.,South China University of Technology | Liang J.,Zhongshan Power Supply Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems

The location and supply area of 110 kV substations are the crux of the coordinated planning between the main system and distribution network. A concept of the coordinated factor and the coordinated planning model is presented, with emphasis on the global balance of system operation. First, the basic properties of substation are analyzed, based on which the properties of operation rate and correlation degree are used to construct the load weight coefficient. Then a bound circle is adopted to delineate the optimization area. With the load weight coefficient as the weight, the locations of substations are optimized using the improved weighted Steiner minimum spanning tree theory. Finally the capability and supply region of the substations can be determined. Actual examples show that the proposed coordinated planning is obviously better than those by traditional models. © 2010 state Grid Electric Power Research Institute Press. Source

A new method for live line measurement of zero-sequence parameters for transmission line containing T-connection line with mutual inductance is proposed. The principle and mathematical model of the proposed method are presented in detail, and the operation mode of transmission line with mutual inductance during live line measurement is given. There are two key techniques in the proposed method, i.e., to acquire the zero-sequence current to be measured and to use Global Positioning System (GPS) as the synchronous signal for the measurement carried out at different place simultaneously. In this paper, the composition of live line measuring device and digital simulation results are given. Finally, the live line measurement process of two 110 kV transmission line containing T-connection lines with mutual inductance, which belong to Zhongshan power network in Guangdong province, China, by the proposed method are described, the live line measurement results are given and compared with the measured results by interference method and the value from empirical estimation. Results from both simulation and on-site live line measurement show that the proposed live line measurement method is feasible, and its measurement accuracy can satisfactorily meet the requirements of engineering measurement. Source

Zhang Y.,Guangdong Key Laboratory of Clean Energy Technology | Xu T.,Guangdong Key Laboratory of Clean Energy Technology | Xu L.,Guangdong Key Laboratory of Clean Energy Technology | Liang J.,Zhongshan Power Supply Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems

To solve the multi-objective coordinated problem of transmission networks planning, an optimal planning model is presented, in which the multi-objective function consists of the minimum investment cost, minimum operation and maintenance cost, minimum flexibility expected expense and minimum social welfare expense. The flexibility expected expense of adapting to the uncertain future is taken into account in the optimal model and is presented from the uncertain scenarios of load growth and power networks emergency. By analyzing the constraint degrees between evaluation factors of each objective function by use of the analytic hierarchy process (AHP), the judgment matrix is built to set each objective function's weight in the mathematical model. The application of the model is validated by network expansion planning on an 18-bus system. © 2010 State Grid Electric Power Research Institute Press. Source

Zhang C.,Zhongshan Power Supply Bureau | Liu X.,Hunan University | He X.,Hunan University | Li C.,Hunan University
Asia-Pacific Power and Energy Engineering Conference, APPEEC

Due to the uncertainties of new energy generation and load, and the increased penetration of new energy, the impact of these uncertain factors on microgrid will increase. In this paper, a coordinated economic operation approach for output optimization of multi-microgrids connected to distribution network is proposed. In the proposed approach, the different coordination dispatching strategies are proposed during peak period, flat period and valley period of a day with different power supply and demand. The economic output optimization model, in which the interactive coordination of multi-microgrid is taken into account, is established. The method is to make full use of complementarities among different microgrids or among different microgrid sources, and remove the uncertainties of intermittent microgrid source's output. Case study shows that the proposed operation approach not only can decrease the dependence on energy storage device, but also reduce the operation cost of microgrid. © 2014 IEEE. Source

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