Postdoctoral Workstation of Yunnan Power Grid Corporation

Kunming, China

Postdoctoral Workstation of Yunnan Power Grid Corporation

Kunming, China
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Li X.,Xi'an Jiaotong University | Deng Y.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Jiang X.,Xian XD Electrical Research Institute Co. | Zhao H.,Northwestern Polytechnical University | And 3 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2017

Recently, fluoroketone and fluoronitrile gases attract great attention as potential SF6 substitutes. We studied the insulation performances of the mixtures of C4F7N and C5F10O with CO2. First, the Antoine constants were fitted by the reported liquefaction temperature data of C4F7N and C5F10O. The saturated vapor pressure characteristics of C4F7N-CO2 and C5F10O-CO2 mixtures were analyzed. Secondly, by combining the Antoine equation and the basic law of vapor liquid equilibrium, the application conditions at limits of environment temperature were discussed. Finally, the critical electric field strengths were determined from the experimental data in literatures, and the insulation performances and potentials of C4F7N-CO2 and C5F10O-CO2 mixtures were discussed. It is found that the electrical strengths of the C4F7N-CO2 mixture under the limits of three environment temperatures (-5℃, -15℃, and -25℃) are all much higher than those of the C5F10O-CO2 mixture, and the proper choice of mixed ratio and pressure for C4F7N-CO2 can provide relatively high electrical strength, low GWP, and liquefaction temperature. Taking the environment temperature limit of -25℃ for example, the electrical strength of the 5%C4F7N-95%CO2 mixture at 0.65 MPa can approximate pure SF6 gas at 0.5 MPa. In addition, the GWPs of C4F7N-CO2 mixtures are below 850 when C4F7N concentration is less than 20%. © 2017, High Voltage Engineering Editorial Department of CEPRI. All right reserved.

Man L.,Shanghai JiaoTong University | Deng Y.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Xiao D.,Shanghai JiaoTong University
Gaodianya Jishu/High Voltage Engineering | Year: 2017

To find a friendly alternative gas with low global warming potential (GWP) for SF6, we investigated insulating properties of c-C4F8/N2 and c-C4F8/CO2 mixtures.Meanwhile, experiments in a sphere-plate electrode were done in different gap distance, pressures, and gas ratio of c-C4F8/N2and c-C4F8/CO2 mixture gas under frequency AC voltage, compared with SF6, c-C4F8, N2 and CO2 in the same conditions. And the decomposition products were detected after breakdown. Experimental results show that the breakdown voltage of mixtures increases as the gas pressure/gap length/ratio of c-C4F8 increases; there is a synergistic effect between c-C4F8 and N2/CO2; In slightly nonuniform field, insulation performances of 30% c-C4F8/N2 and c-C4F8/CO2 mixed gas are equal to 75% and 79% of pure SF6 in 0.1 MPa; the synergistic effect coefficients of c-C4F8/N2 and c-C4F8/CO2 in 5%~30% mixing ratio are between 0.20~0.79 and 0.15 ~0.65, respectively. From the insulating properties, liquefaction temperature standpoint and environment, c-C4F8/N2 and c-C4F8/CO2 gas mixture may be used as an alternative for SF6 gas in electrical equipment. © 2017, High Voltage Engineering Editorial Department of CEPRI. All right reserved.

Yang F.,Chongqing University of Technology | Gao B.,Chongqing University of Technology | Chen M.,Chongqing University of Technology | Wei L.,Postdoctoral Workstation of Yunnan Power Grid Corporation | And 2 more authors.
International Journal of Applied Electromagnetics and Mechanics | Year: 2015

The operation environment of electric power cables undergoes more and more natural damages, such as earthquake, flood which would result in the change of unit capacitance and inductance of power cables, as well as the reactive power. In this paper, a method of ''distributed model'' based on Poynting vector and space-stepping finite difference frequency domain (FDFD) is proposed to calculate the reactive power of power cables. Comparing with the method of ''lumped model'', it can calculate the reactive power of power cables without computing the unit capacitance and inductance which are difficult to get, especially when the cable trench is fill with ponding, sludge and collapse. Calculation of the reactive power has been carried out in consideration of eccentric and water infiltration cases, and results indicate that ponding environment will lead to a substantial increase of capacitive reactive power. Capacitive reactive power increase with cable eccentricity degree; when cables suffer both water ingress and a 2.5 mm eccentricity degree, the increased capacitive reactive power will reach 51.98%. © 2015 - IOS Press and the authors. All rights reserved.

Zhang W.-B.,Kunming University of Science and Technology | Zhang W.-B.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Chen J.-L.,Kunming University of Science and Technology | Suo C.-G.,Kunming University of Science and Technology | Gui W.-S.,Kunming University of Science and Technology
Proceedings of 2012 3rd International Asia Conference on Industrial Engineering and Management Innovation, IEMI 2012 | Year: 2013

Least square support vector machine (LS-SVM) is widely used in the regression analysis, but the prediction accuracy greatly depends on the parameters selection. In this paper, Simple Genetic Algorithm is applied to optimize the LS-SVM parameters; correspondingly, the prediction accuracy is improved. Sensors are always sensitive to several parameters, and this phenomenon is called cross-sensitivity which restricts the application of sensors in engineering. In order to reduce cross-sensitivity, the model of multi-sensor system measurement is established in this paper. For solving the nonlinear problems in the model, LS-SVM is used to establish the inverse model. It proves that the method has a high forecasting precision. It is beneficial to the application of sensors. © 2013 Springer-Verlag Berlin Heidelberg.

Gao B.,Chongqing University | Yang F.,Chongqing University | Chen M.,Chongqing University | Duan P.,Chongqing Electric Power Company | And 2 more authors.
Applied Computational Electromagnetics Society Journal | Year: 2015

An improved local Petrov-Galerkin method (MLPG) is proposed to solve the general electro-thermal problems in the paper, in which the method to determine the support domain is improved. Two electro-thermal problems are analyzed and solved with the method in the paper, the results indicate that the precision of the final solution is increased. In addition, the electrothermal field and ampacity of ±800kV ultra high voltage direct current (UHVDC) transmission line are calculated, great accuracy of the solution to the electro-thermal coupling problem is obtained. Results indicate that the maximum and minimum value of surface electric field intensity on each subconductor lies on the inner and outer surface, the ampacity of transmission line varies almost linearly with environment temperature inversely.

Liu S.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Wang J.,Huazhong University of Science and Technology | Wang D.,Yunnan Electric Power Research Institute
World Academy of Science, Engineering and Technology | Year: 2011

A case study of the generation scheduling optimization of the multi-hydroplants on the Yuan River Basin in China is reported in this paper. Concerning the uncertainty of the inflows, the long/mid-term generation scheduling (LMTGS) problem is solved by a stochastic model in which the inflows are considered as stochastic variables. For the short-term generation scheduling (STGS) problem, a constraint violation priority is defined in case not all constraints are satisfied. Provided the stage-wise separable condition and low dimensions, the hydroplant-based operational region schedules (HBORS) problem is solved by dynamic programming (DP). The coordination of LMTGS and STGS is presented as well. The feasibility and the effectiveness of the models and solution methods are verified by the numerical results.

Sun X.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Gao M.,Yunnan Electrical Dispatch Center | Liu D.,Hubei Engineering University | Hou X.,Chongqing Electric Power Research Institute | Yuan R.,Yunnan Electrical Dispatch Center
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

Prony method (PM) is unsuitable for processing the fault signals containing components with uncontinuous or abrupt changes. The adaptive PM (APM), by adaptively segmenting a signal, improves PM's performance, but it takes fixed step to search the subsegments' dividing points, so efficiency is low and execution time is long. This paper proposes a modified APM (MAPM) that introduces variable-step measure and greatly promotes the searching efficiency. Simulation results show that MAPM's signal fitting and parameters estimation are of high accuracy, and the signal interpolation and prolongation based on it are adaptive while the traditional methods are not. A real-life fault signal is analyzed and processed by MAPM, again showing its superior performance and establishing its basis for extensive use in electrical engineering. © 2010 Chin. Soc. for Elec. Eng.

Liu S.,Post Doctoral Workstation of Yunnan Power Grid Corporation | Liu S.,Huazhong University of Science and Technology | Li X.,Jilin Huaqiao Foreign Languages Institute
2010 International Conference on E-Product E-Service and E-Entertainment, ICEEE2010 | Year: 2010

The constrained hydroelectric unit commitment problem is turned into an unconstrained optimization problem by means of penalty function method, and to improve the diversity and search ability, the classical particle swarm optimization (PSO) approach is enhanced by incorporating a genetic crossover operator and a self-adaptive decreasing inertia weight. Then the enhanced PSO is used to solve the hydroelectric unit commitment problem, with the numerical results, the proposed method is verified to be feasible and effective. ©2010 IEEE.

Sun Y.,North China Electrical Power University | Tu Y.,North China Electrical Power University | Wang C.,North China Electrical Power University | Wang S.,North China Electrical Power University | And 3 more authors.
Proceedings of the IEEE International Conference on Properties and Applications of Dielectric Materials | Year: 2015

With the acceleration of urbanization and the rapid development of industry and agriculture, fog-haze occurs frequently in most parts of China, which is a serious threat to the safe operation of the power system. The effects of fog-haze on the insulators represent in two aspects: a) increasing contamination on the surface of insulators and b) increasing the leakage current and decreasing the flashover voltage of insulators due to the wet deposition. Therefore, in this paper, naturally polluted insulators under fog-haze were taken as test objects, and the contamination and AC pollution flashover characteristics of different kinds of insulators were studied. According to the test results, contamination on the insulator surface is increased significantly under fog-haze in a short time. Compared with porcelain and glass insulator, the composite insulator shows more serious contamination under fog-haze environment. Saturated moisture time of two-shed type porcelain insulator is the shortest and saturated moisture leakage current of that is the largest, while composite insulator has the longest saturated moisture time and the smallest saturated moisture leakage current. Composite insulator is with the largest flashover voltage gradient, which is followed by bell type porcelain insulator and deep under-rib type glass insulator, and that of two-shed type porcelain insulator is the smallest among these insulators. © 2015 IEEE.

Wang C.,North China Electrical Power University | Li T.,North China Electrical Power University | Peng Q.,Postdoctoral Workstation of Yunnan Power Grid Corporation | Tu Y.,North China Electrical Power University | And 2 more authors.
2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2014 | Year: 2014

Formation of contamination flashover arc in composite insulator is closely related to leakage current, which is affected by surface contamination and humidity. In this paper, a composite insulator in service over 6 years was taken as a sample, and leakage current tests were carried out in an artificial climate facility, which can provide experiment conditions with a series of humidity and contamination levels. Based on leakage current information collected from different flashover pattern, reasons of variation in leakage current waveforms were analyzed. The results indicate that, under high humidity conditions, the higher artificial contamination level leads to smaller leakage current phase shift between applied voltage and higher resistive current. The current waveform distortion is considered to be mainly related to harmonic components resulting from arc discharge. Hence, characteristics of leakage current waveforms can be exploited to evaluate surface discharge of the composite insulator. © 2014 IEEE.

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