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Wensi C.,North China University of Water Conservancy and Electric Power | Chuanjin H.,Zhengzhou University | Guozhi Z.,Henan Transmission and Transformation Construction Corporation
Sensors and Transducers | Year: 2013

To realize high-accuracy measurement parameter of transient disturbance signal, Aiming at the transient disturbance signal is nonlinear, irregular and mutation characteristics, the local mean decomposition (LMD) algorithm is applied to the transient disturbance detection in power system for the first time. Transient disturbance signal is adaptively decomposed into a number of Product Function (PF for short) by the algorithm, and the PF is made of the envelope signal and pure Frequency Modulation signal. The amplitude and PF frequency respectively obtained by the envelope signal and pure Frequency Modulation signal. Further combination, we can get the original signal of time frequency distribution curves. The amplitude and frequency curve, not only can accurately locate the disturbance moments, but also can detect the voltage fluctuation amplitude of typical transient disturbance signal, such as voltage swell, and voltage sag, The simulation waveform was influenced by "end effect" smaller. Simulation results show that LMD Algorithm is effective, and has better locate accuracy and computing speed than the HHT algorithm. © 2013 IFSA.


Cao W.,North China University of Water Conservancy and Electric Power | Tan L.,North China University of Water Conservancy and Electric Power | Zhang G.,Henan Transmission and Transformation Construction Corporation | Qiu D.,North China University of Water Conservancy and Electric Power
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

The composing of high-frequency trapper is briefly introduced and an algorithm based on correlation method is presented for testing its blocking frequency characteristics, which performs directly the cross-correlation computation for two measured signals to effectively separate part of noise components. A set of practical formulas is summarized for calculating the impedance and resistance components of trapper. The effectiveness of the proposed algorithm is verified by Matlab simulation. A DSP-based trapper test system is designed, including the power supply, microprocessor, RAM, control logic and so on. Its main program includes the modules of initialization, keyboard scanning, data processing and result display. The K-type wideband tune trapper with typical parameters is tested and the results are compared with the calculated results, which demonstrate the high accuracy, high speed and excellent anti-noise performance of the designed test system.


Wensi C.,North China University of Water Conservancy and Electric Power | Chuanjin H.,Zhengzhou University | Guozhi Z.,Henan Transmission and Transformation Construction Corporation
Information Technology Journal | Year: 2013

To realize high-Accuracy measurement parameter of voltage flicker, Focusing on the amplitude modulation wave and inter-harmonics fluctuation problem in voltage flicker based on conventional algorithm, the Local Mean Decomposition (LMD) algorithm is adopted to analyze voltage flicker parameter identification in power system for the first time. LMD algorithm principles were briefly introduced, signal adaptively is decomposed into a number of single-component FM-AM function (Product Function, PF) by LMD. For mixed voltage flicker signal, the fundamental component that modulated by the low frequency modulated waves and inter-harmonic components are separated based on LMD after the first decomposition. Amplitude modulation function of fundamental component contains time-varying amplitude modulated wave, Amplitude and frequency information can be obtained by its LMD. Amplitude modulation function of inter-harmonic components corresponding to the amplitude, frequency can be obtained by pure frequency modulation function. The paper selects typical voltage flicker signal, Comparison of the simulation results by LMD algorithm and HHT algorithm, simulation results show that Because the LMD algorithms get a PF by dividing by the envelope function and the number of "Screening" is relatively less, the end effect is small. The flicker parameter in the steady state basically does not change based on LMD. Simulation results prove LMD superiority, the method is simple, rapid and high accuracy. The results show the feasibility and accuracy of LMD algorithm. © 2013 Asian Network for Scientific Information.


Zhang G.-Z.,Henan Transmission and Transformation Construction Corporation | Guo L.,Henan Transmission and Transformation Construction Corporation | Cai W.,Henan Transmission and Transformation Construction Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

For the purpose of improving the filtering efficiency and reducing the labour intensity in Nanyang UHV substation project, auto filtering system which can control the electric-magnetic valves is developed. The system can do different and single oil tank filtering process according to the oil-levels monitored and programmed software. Also, it can control the valves directly. The system is composed of the monitoring and control unit, sub-controller, vacuum oil filter, tanks, sensors and oil pipes. The process control units utilize the S7-200 series PLC of SIEMENS AG. The principle of the system constitution, design of the system software and configuration of the human-machine interface are introduced. In Nanyang UHV substation project, the system works stably and reliably. It's praised by the staff in the station.

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