Power Quality Analysis Based On Wavelet Transform

In late years, with the large scale growth of the society national dividend, the electricityrequest is getting higher and higher in the industrial production and the daily life, on the otherhand, as the nonlinear equipments including power electronic apparatus are applied, which haveworsened the power quality day by day. It should detect the power quality issues quickly andexactly, so it can control and treat the issues, whole it confirm the types of the issues, as that wetake them into analysis effectively.In this paper, it has introduced the definition about power quality, classifies power qualityphenomena, and explains the cause of power quality. According to the methods which areresearched by domestic and foreign researcher, it can discuss Fourier transform, short-timeFourier transform and wavelet transform, as so it would use this theoretical knowledge to makethe following research, the main research works and achievements are outlined as follow:1. As the harmonics problem of stead-state power quality in the power system, it useswavelet packet decomposition and reconstruction to analyze harmonics. Measuring theharmonics voltage, harmonics current, power RMS is used by the algorithm. Using the Db40wavelet function, it could analysis well. According to the analysis in MATLAB, it provesanalyze the harmonics well.2. Detecting and analyzing the non-steady signal is a focus of analysis of transient powerquality in the electrical power system. it use the wavelet transform modulus maxima ofsingularity, so the wavelet transform is applied to analyze the power quality transient, it canlocate the position of the signals of voltage swell, voltage sag, temporary interruption, voltageoscillatory, voltage impulse. At the end, according to the analysis in MATLAB, it can obtain thesignal parameters, such as beginning and ending time, duration and amplitude of the transient.Through the simulations and experimental measurement， it proves that the wavelettransform has good result in measurement and analysis of power quality in the electrical powersystem.