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Liu J.,Shanghai JiaoTong University | Liu J.,China Electric Power Research Institute | Li X.,Dongfang Electronics | Liu D.,Shanghai JiaoTong University | And 2 more authors.
IEEE Transactions on Smart Grid | Year: 2011

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.

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

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 | Year: 2016

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.

Feng Z.,China Three Gorges University | Lu L.,China Three Gorges University | Feng J.,Yunnan Power Grid Corporation
2011 International Conference on Electrical and Control Engineering, ICECE 2011 - Proceedings | Year: 2011

In order to improve the lightning withstand level of transmission lines, to reduce line lightning trip-out rate and the accident rate, to improve power supply reliability, grounding resistance in grounding grid of transmission line tower should be effectively ameliorated. As to the transmission line tower grounding grid in the plateau mountainous with thin soil, dry soil and complex geological conditions, the grounding electrode landfill layer is shallow and grounding resistance is significantly higher. Improvement of grounding grid and application of special resistance reducing material can reduce the the grounding resistance effectively. This technology has been applied to an actual construction reformation of transmission line tower grounding grid. The comparison of the test results verifies that grounding resistance can be effectively reduced by using a combination of above methods in complex geological environment. © 2011 IEEE.

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 | Year: 2013

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.

Li Z.,Yunnan Power Grid Co.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

The entire voltage loss caused by the outlet line failure is studied for the chain-structured afflux station of small hydros. To prevent it, the impact of the asynchronous paralleling on grid and devices should be avoided, as well as the reclosing with lines, transformers, and even shutdown generator, which is off-loaded but still connected with grid. The concept of "reclosing after separation" is put forward, which separates the hydros first and re-closes then the lines. The solutions are given, such as the reclosing separation, the high-frequency separation, etc. and their adaptability to different operating modes, fault points, fault lines, fault types is analyzed. The possibility of maintaining the voltage of afflux station during its outlet line failure is discussed and the optimal solution is given: separate all stations except one with the best speed governor to maintain the station voltage and realize the fast automatic grid recovery.

Chen L.,Huazhong University of Science and Technology | Tang Y.J.,Huazhong University of Science and Technology | Song M.,Yunnan Power Grid Corporation | Shi J.,Huazhong University of Science and Technology | Ren L.,Huazhong University of Science and Technology
Physica C: Superconductivity and its Applications | Year: 2013

Since the introduction of superconducting fault current limiter (SFCL) into electrical distribution system may be a good choice with economy and practicability, the parameter design and current-limiting characteristics of a 10 kV voltage compensation type active SFCL are studied in this paper. Firstly, the SFCL's circuit structure and operation principle are presented. Then, taking a practical 10 kV distribution system as its application object, the SFCL's basic parameters are designed to meet the system requirements. Further, using MATLAB, the detailed current-limiting performances of the 10 kV active SFCL are simulated under different fault conditions. The simulation results show that the active SFCL can deal well with the faults, and the parameter design's suitability can be testified. At the end, in view of the engineering feasibility of the 10 kV active SFCL, some preliminary discussions are carried out. © 2013 Elsevier B.V. All rights reserved.

Yu H.,Yunnan Power Grid Corporation | Wei J.,Yunnan Power Grid Corporation | Wang D.,Yunnan Power Grid Corporation
International Journal of Advancements in Computing Technology | Year: 2012

The X-ray influence for SF 6 gas of the electrical equipment is wanted to know in charged and no electrical charges, which can convenient for the X-ray digital radiography (DR) technology is applied to the visual detection electrical facility in the non-disassembly. Thus, in this paper, it is proposed the influence research on X-ray irradiation for the SF6 gas of the electrical equipment by the highest X-ray energy. The X-ray machine of the portable high frequency industry is used to irradiate the SF6 gas of the Gas Insulate Switchgear (GIS) power equipment in charged and no electrical charges. The experimental results indicate that X-ray has no influence for the SF 6 gas of the electrical facility in charged or no electrical charges. At the same time, X-ray has no influence for the initial voltage of the partial discharge on the electrical equipment. Thus, the research of this paper can provide the theory basis for the electrical equipment application area of the X-ray digital radiography technology.

Hu Z.,Wuhan University | Li H.,Yunnan Power Grid Corporation | Wen X.,Wuhan University | Zhang C.,Wuhan University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2012

An online monitoring method of transmission conductor wave and wind gallop is proposed based on DGPS (Differential Global Positioning System), which obtains the spatial location information of transmission conductors in real time by DGPS technology and sends it to the server on ground by wireless transmission technology. The monitoring program of server converts the spatial location information into the spatial position information in Cartesian coordinates system, the error of which is processed by the artificial neural network. The reproduction program of server reproduces the tracks of conductor wave and wind gallop according to the real-time spatial location information. Results of site test for a 500 kV transmission line show the wave and wind gallop of transmission conductor are monitored in real time with the accuracy of centimeter class.

Pan X.,Yunnan Power Grid Corporation | Zhou M.,North China Electrical Power University | Kong X.,North China Electrical Power University | Wu Y.,North China Electrical Power University | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

There are always some different correlations between wind farms in a power grid. This paper uses inverse Nataf transformation to generate correlated wind speed samples to get the correlating wind farms' generations. Considering the uncertainty of wind speed, the actual production of each wind power plant is considered as a negative Weibull random distribution load and characterized by its historical time series data. The spatial correlations of wind power plants are properly modeled through stationary variance-covariance matrices. Wind farms are included in modified IEEE 30-bus and IEEE 118-bus systems. Monte Carlo simulation is adopted to quantitatively analyze how the indicators of optimal power flow results volatilities as a result of an increasing correlation among wind farms. © 2013 State Grid Electric Power Research Institute Press.

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