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Gao F.L.,Kaifeng Power Supply Company | Fang Y.W.,China Communications Construction Company Ltd.
Applied Mechanics and Materials | Year: 2014

According to the case that mass concrete in solid sections of lower pylon column of Jiashao Bridge was easy to crack in construction because of the bigger section size, larger content of cementitious material and lower water binder ratio, the temperature and thermal stresses distribution of mass concrete was simulated and temperature control scheme was adjusted constantly based on the results of field temperature monitoring. Through taking some temperature control measures such as applying circulating cooling water and prolonging the time appropriately, thermal insulation and moisture retention curing, extending the form removal time and controlling the quality of concrete, harmful cracks did not appear in solid sections of lower pylon column of Jiashao Bridge and anticipated temperature control requirements were achieved. © (2014) Trans Tech Publications, Switzerland. Source

Yun W.,Zhongyuan University of Technology | Ying X.,Zhongyuan University of Technology | Sheng Z.,Zhongyuan University of Technology | Ming X.,Zhongyuan University of Technology | Xue H.,Kaifeng Power Supply Company
Advanced Materials Research | Year: 2012

A MPPT (Maximum Power Point Tracking) control method of PV (Photovoltaic) generation system is proposed based on the shortcoming of the existing MPPT algorithms. The method applies CVT (Constant Voltage Tracking) algorithm to adjust the working point of PV array near the MPP (Maximum Power Point) for fast tracking when working point is far from MPP, and uses adapting duty cycle perturb method to optimize the steady state characteristic of MPP for effectively eliminate the output power oscillation under the setting precision. Its model is established and simulated with Matlab/Simulink. The CVT, duty cycle method and proposed methods are simulated respectively and simulation results show that, the proposed method tracks the MPP exactly and quickly and improves the energy conversion efficiency of PV generation system by eliminate the output power oscillation around MPP. Its fast response speed improves the static and dynamic performance of photovoltaic power system. Source

Zhao J.-J.,Henan University | Hu W.-W.,Henan University | Gu X.-G.,Henan University | Yang P.,Kaifeng Power Supply Company
2011 3rd International Workshop on Intelligent Systems and Applications, ISA 2011 - Proceedings | Year: 2011

In this paper, An algorithm which uses an improved threshold algorithm in the de-noising of electricity signals and then extracted the fault feature by db10 wavelet, is proposed because of the features in the fault of high voltage electric power measurement system. Experiment results show that it is more efficient to de-noising by the improved threshold algorithm in wavelet analysis. The method in the diagnosis of fault of electric power measurement is very practical valuable. © 2011 IEEE. Source

Xu M.,Zhengzhou University | Yang Y.,Zhengzhou University | Zhang M.-Z.,Zhengzhou University | Bai C.-T.,Kaifeng Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

An interpolated FFT algorithm based on the trinomial cosine exact Blackman window is proposed. This paper first discusses the frequency response of the exact Blackman window, then derives the formulas of interpolated FFT algorithm based on the exact Blackman window in detail. The cubic spline function is used to calculate correction factors for frequency and complex amplitude. Simulation results demonstrate that by using the cubic spline function, the amplitude error is less than 0.1%, the frequency error is less than 0.01 Hz, and the phase error is less than 5%. The new interpolated FFT algorithm proposed in this paper can effectively enhance the measuring accuracy of power system harmonics. It has a good real-time performance with less calculations compared with other interpolated FFT algorithms based on quadrinomial cosine window. Source

Wang S.-H.,Henan Electric Power Company | Peng X.-Y.,Kaifeng Power Supply Company | Han X.,Henan Electric Power Company | Lu S.-H.,Kaifeng Power Supply Company | Song J.-J.,Xiuwu County Electrical Power Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

To meet the new requirement of direct-current power supply system in the <>, some problems arised in large-scale DC power system retrofit are analyzed and solved. In regard to the problem of polarity reversed when changing the circuit breaker of alternating current to the circuit breaker of direct current in DC power supply system, through the understanding of configuration of direct current's circuit breaker and arc extinction theory, acceptable connection method is found. For the problem of switch from looply connected to divergently connected power supply in DC power supply system's load network, three load network transformation proposals are put forward with advantages and disadvantages analysis. In DC power supply system, aiming at the problem of range coordination and model selection using parameters, also using practical tested figures on site, referencable advice is given to circuit breaker's capacity configuration. Source

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