Time filter

Source Type

Wei J.-L.,Henan Electric Power Research Institute | Xu H.,Jiaozuo Power Supply Company | Wang J.-F.,Xi'an Jiaotong University | Zhang G.-J.,Xi'an Jiaotong University
Proceedings of the IEEE International Conference on Properties and Applications of Dielectric Materials | Year: 2012

To quantificationally apply the results of polarization and depolarization currents (PDC) measurement for condition evaluation of oil-paper insulation in power transformer, the differential time-domain spectroscopy (DTDS) theory and the extraction technique of sensitive characteristic parameters are introduced. A set of oil-immersed paper samples are thermally acceleratedly aged at high temperature (∼150°C) in laboratory based on the developed platform for oil-paper insulation thermal aging and dielectric response test. Under different temperatures (30, 40, 50, 60, 70°C) and different aging degrees, PDC tests are performed on one of the samples by real-time tracking during the whole aging period. And at each aging stage, the aided tests, such as moisture content dissolved in oil and degree of polymerization (DP) of cellulose paper are measured. The test and analysis results show that aging condition has evident effect on DTDS curves. With sample aging, the DTDS curve shifts upwards. The extracted characteristic parameter, polarization response time t1 of the interfacial polarization between oil and pressboard, is regular and sensitive to aging condition changing. The influence mechanisms of aging on the time domain dielectric properties are analyzed. The empirical formula representing the relation among temperature, aging condition, and dielectric response in time domain is developed by means of 3-D surface fitting technique, to preliminarily investigate the application method of time-domain dielectric test. © 2012 IEEE.

Tang M.,Xi'an Jiaotong University | Lei M.,Xi'an Jiaotong University | Bai F.,Xi'an Jiaotong University | Wei J.,Henan Electric Power Research Institute | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2014

In order to obtain more specific information of insulation states of oil-paper insulation system from time-domain data, we proposed a novel method for parameter identification of extended Debye model for oil-paper insulation system. In the method, the depolarization current spectrum of polarization and depolarization current (PDC) in experiments was obtained by the fast Fourier transform (FFT). Then combining the vector fitting method (VFM) and nonlinear fitting algorithm (FNA), we derived the distribution of the poles and residues of the obtained spectrum, and calculated the branch parameters of extended Debye models. The PDC and frequency domain spectrum (FDS) measurements were performed on some oil-impregnated pressboard samples, which were in various aging states and under different temperatures. The corresponding extended Debye models to the samples were obtained from the PDC measurement, based on which curves of tanδ varying with frequency were figured out and then compared with those from FDS measurements. The tanδ obtained from PDC agrees well with that from FDS under low frequencies, which verifies the proposed method. With further analysis, it is suggested that, for oil-paper insulation system, FDS measurement should be conducted in high frequency range but replaced by PDC measurement in low frequency range, for saving time, i. e. the combination of FDS and PDC methods could help to improve the efficiency of measurement of on-site oil-paper equipment.

Cai W.,Wuhan University | Le J.,Wuhan University | Jin C.,Wuhan University | Liu K.-P.,Wuhan University | Li S.-X.,Jiaozuo Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

This paper proposes a substation anti-mal-operation system for the operation staff positioning based on the real-time signboard visual identifying technology. In this system, real video of the signboard of current space for identification is captured by a portable video capture device. And then it can distinguish that the operation staffs go into the wrong space whether or not refering to the operation order. This paper gives the operational principles and the design of each component of the whole system. The theories and realization of signboard border detecting method by using Hough transformation and signboard character splitting method by using projection method are also introduced in detail. The correctness, effectiveness and engineering applicability are verified through the results of the lab tests and trial operations at last.

Changzhou G.,Jiaozuo Power Supply Company | Jie L.,Jiaozuo Power Supply Company | Xiaoping C.,North China Electrical Power University | Ying G.,North China Electrical Power University
Lecture Notes in Electrical Engineering | Year: 2012

In this article, through selecting and calculating of one city's index of industrialization and urbanization from 1990 to 2005, we established multiple linear regression model by industrialization and urbanization index as a parameter based on classical linear regression model. Then test the model by historical data of power consumption from 2006 to 2008. The test error shows that the model of the city power load forecasting result is quite satisfactory, so we use it to predict electrical load in 2011-2015. The result can provide reference for the planning of the Grid. © 2012 Springer-Verlag GmbH.

Chen Y.,Zhengzhou University | Lu S.-H.,Jiaozuo Power Supply Company | Yang L.-X.,Zhengzhou University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

As trees growth simulation algorithm(TGSA) has the disadvantage of bad convergence stability and it is difficult to find the global optimal solution in solving large scale reactive power optimization problem, a new reactive power optimization algorithm called chaotic trees growth simulation algorithm(CTGSA) is presented by using the characters that chaos optimization algorithm is sensitive to initial value and has ergodicity. An operator called chaos immigrant is introduced to the process of TGSA to improve the quality of feasible solutions in the growing point collection and keep the diversity of feasible solutions, by which the new algorithm has better convergence stability and optimization precision. When the algorithm is used for IEEE 30-bus system, the results show that the algorithm has strongly global optimization ability and convergence stability.

Yang L.-X.,Zhengzhou University | Zhang L.,Zhengzhou University | Zhang S.-Q.,Jiaozuo Power Supply Company | Lu S.-H.,Jiaozuo Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

In order to research the investment benefit of the rural power network, the data envelopment analysis (DEA) is applied in this paper. In this method, the input and output indices are set from the viewpoint of input-output and the utilization efficiency of these power networks which are calculated and evaluated by DEA. And following results are obtained, including the investment benefit of the rural power network, the disparity between realism and optimal conditions of inefficient network, the redundant statistics of input factors. Evaluating the existing network and the planning network in a collection of identical elements, it can quantify the impact of the network planning on improving the investment benefit. The method can help the decision-makers to establish or modify network planning so as to improve the efficiency of allocating resource. Calculation and analysis results of actual case show that the proposed method is scientific and rational.

Loading Jiaozuo Power Supply Company collaborators
Loading Jiaozuo Power Supply Company collaborators