Dissertation > Industrial Technology > Electrotechnical > Transmission and distribution engineering, power network and power system > Power system automation > Distant measurement and remote control

Power quality monitoring system

Author LiLanFang
Tutor LiuKaiPei
School Wuhan University
Course Power Electronics and Power Drives
Keywords Power Quality Fourier Transform Short-time Fourier transform Wavelet Transform Wavelet Denoising Fast Fourier Transform Mallat algorithm Online Monitoring
Type Master's thesis
Year 2004
Downloads 496
Quotes 7
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In recent years, increasing power quality problems caused by the power sector and the user's attention. In order to take reasonable measures to improve power quality , power quality must first establish monitoring and analysis system, to correctly detect power quality , evaluation and classification. This paper summarizes the existing power quality analysis method is proposed based on wavelet transform and Fourier transform method of combining power quality analysis . This paper systematically introduces the power quality phenomena and their theoretical basis , a variety of power quality disturbances classification , definition, characteristics and causes were elaborated and briefly introduced China's power quality standards. Secondly, the Fourier transform, short-time Fourier transform and wavelet transform these three basic principles and methods of analysis in the field of power quality application status did explore and compare and analyze the characteristics of the various methods and their application conditions. Furthermore , through the large number of typical signal simulation analysis establishes the power quality analysis algorithms, and the superiority of this method is verified . The actual power quality signal may contain hypermutation part and the noise part . Adaptive wavelet transform them of power quality disturbance signal de-noising a traditional low-pass filter can not match advantage . In this paper, wavelet denoising method of signal pre-processing, to obtain good results . Based on the singularity of the signal detection theory , the use of high-frequency coefficients of wavelet decomposition whether the modulus maxima as the distinction between steady and unsteady phenomena criterion . Using fast Fourier transform method for harmonics , flicker and pure sine wave phenomena such as steady-state analysis. A fast algorithm using wavelet transform - Mallat algorithm to determine the duration of the unsteady disturbance and disturbance waveform , thereby distinguish between the various non-stationary disturbances . Finally, from the power quality monitoring perspective , based on wavelet transform and Fourier transform power quality analysis methods designed to TMS320VC33 as the core hardware monitoring system , using C language programming power quality analysis algorithms.

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