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Yao C.,Chongqing University of Technology | Long Y.,Chongqing University of Technology | Wu H.,Chongqing University of Technology | Mi Y.,Chongqing University of Technology | And 4 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation

Among the traditional lightning current monitoring systems, it is hard to ensure measuring lightning currents directly, expediently, accurately and safely at the same time. So aiming at solving the problem of measuring the lightning current on the overhead transmission lines, it is necessary to create a novel lightning current monitoring system based on the differential-integral loop which has been widely applied in the pulse power measurement technique to achieve non-contact measurement of the lightning current on the lines under the consideration of the field conditions of lines. In this paper, the method of acquiring the lightning current waveforms and the design of the novel monitoring system are introduced. In the laboratory, the results of the experiments by using the high impulse current generator to simulate the lightning currents show that: for the certain measured distance, through adjusting the sensor parameters and choosing reasonable electromagnetic shielding measures, the lightning current monitoring system can collect the data of the high impulse current accurately and completely, and the monitoring system has the advantages of safety, high EMC performance and accuracy. At last, the field photos of this lightning current monitoring system are shown, and the field data proves that it can effectively meet the requirements of the monitoring system and be very convenient to popularize widely. © 1994-2012 IEEE. Source

Liu J.,Shanghai JiaoTong University | Liu J.,China Electric Power Research Institute | Liu D.,Shanghai JiaoTong University | Liu H.,Yunnan Power Grid Corporation | Mao P.,Jiangxi Electrical Power Company Extra high Voltage Sub company
IEEE Transactions on Smart Grid

The control center in smart grids requires the collaboration among different specialized groups to ensure the safety, reliability, greenness and efficiency of power system. However, each specialized group is interested in different aspects of the network model. In order to improve the teamwork and timeliness, the fundamental models should be managed in a unified way. This paper summarizes the requirements for data management of fundamental models, presents a concept of three-mode models, and designs the architecture of generic model access services. With the generic model access services, the differences of real-world model databases will be shielded, and the future virtual model can be managed as versions. The upper applications can obtain the fundamental model information through the data broker component and business model data through the business data organizing component. © 2011 IEEE. Source

Liu J.,Kunming University | Wang C.-B.,Hefei University of Technology | Liu L.,Yunnan Power Grid Corporation | Sun W.-H.,China Earthquake Administration
Space Weather

The Hilbert-Huang transform (HHT) is an adaptive data analysis method that can accommodate the variety of data generated by nonlinear and nonstationary processes in nature. In this paper, we focus on the small geomagnetically induced current (GIC) at the local substations in low-latitude power grid of China, responding to a moderate storm on 14-18 July 2012. The HHT is applied to analyze the neutral point currents (NPCs) of transformers measured at different substations, and the GIC indices converted from local geomagnetic field measurements. The original data are decomposed into intrinsic mode functions (IMFs) using the ensemble empirical mode decomposition. After removal of the quasi-diurnal components related with the solar quiet variation, the IMFs representing storm disturbances are transformed into Hilbert energy spectra. The results show that some transformers have more or less responses to the moderate storm in the form of Hilbert energy spectra with the frequency around 2-3mHz. A comparison on the amplitude changes of the spectra total energy of NPCs' perturbation during storm time intervals at different sites suggests that a shell type of three-phase single transformer group seems to be more vulnerable in the storm. Although the low-latitude power grids usually show very small GIC, these can be used to investigate the potential risk of space weather to the system. ©2016. American Geophysical Union. Source

Huang Z.,Yunnan Power Grid Corporation
Proceedings - 2015 6th International Conference on Intelligent Systems Design and Engineering Applications, ISDEA 2015

In recent years, SDN develops rapidly all around the world, known as a great renovation for the traditional network architecture. SDN principle advantages contain separation of hardware and software, separation of control and management, centralized management, open source, bringing low cost, high efficiency and flexible business. Power Grid has complicated application system, and data center is the most important, so introducing SDN can build a better IT infrastructure to supply application services. In order to drive network through application and enhance the convenience of application deployment and maintenance in datacenter, this paper presents a SDN group policy model with application centric. Firstly, a universal SDN based environment is developed, and the server physical location, security strategy and network address IP are decoupled by introducing and extending VXLAN technology. Secondly, combined with the grid application, a group policy control method is described in detail. The introduced SDN group policy control model will enhance the SDN centralized management and control functions, and simplify the network application deployment and maintenance. © 2015 IEEE. Source

Xu Y.-Q.,North China Electrical Power University | Liu W.-X.,North China Electrical Power University | Pan X.,Yunnan Power Grid Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

For the complex power grid with wind farms, forecasting the stability of power grid fast while considering the randomness of load and wind farms will benefit the safe operation of power systems as well as provide reference for grid scheduling. The online static voltage stability of power grid is estimated by multi-linear regression models (MLRM) based on off-line computation results. This is the specific process: Using Monte Carlo simulation to calculate true values of system's static voltage stability margin (SVSM) based on continuous power flow, and these true values will compose estimating sample space; when using MLRM method, the reactive power reserves of generator buses which influences voltage amplitude will become explaining variables and the voltage stability margin will become explained variables, then multivariate linear regression equation is established to compute the regression coefficients; forecasting the online SVSM finally. The test cases on improved IEEE 14-bus system and IEEE 118-bus system demonstrate the effectiveness of forecasting static voltage stability margin by MLRM method. Source

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