Study On The Real-time Harmonic Detection In Power System Based On Wavelet Transform And FFT

Expanding the Power network and improving the degree of automation, the harmonic pollution has become the main factor of affecting system security and power quality that causing serious damage of power system. With the new theory and new technology development. the research of harmonic measurement also gradually improved, it is to solve the problem of harmonic suppression and provide reliable analysis data. It leads the development direction of harmonic detection to be highly efficient, accurate and real-time detecting harmonic component.This paper described in detail the harmonic generation, hazard and detection on the basis of standards, and then analyzes the current situation and existing problems of harmonic detection, in order to defined the research target and implementation effect. According to the characteristics of harmonic, wavelet transform and FFT for harmonic measurement were analyzed and summarized. Then the paper put forward the detecting method that based on Wavelet and FFT for harmonic in power system. Combined with the research of algorithm, it design the DSP and ARM processors working mode in the conditions of real-time and reliability, providing the hardware support of the detection effect.Through the establishment of the harmonic signal model, in MATLAB software environment the joint detection algorithm simulation and analysis are carried out. The results show that the Fourier transform can reflect the signal in the frequency domain information, and time-frequency localization characteristics of wavelet transform can extract the signal time frequency characteristics at the same time. It has very good ability to analyze the mutation and the discontinuous point detection in the signal. The combination of these two algorithms, FFT detects the signal of the steady-state harmonic components and extracts the frequency information of the signal. Separation of non steady state component from it, wavelet transform can not only determine the instant mutation moment, but also in the noise interference can distinguish its characteristics accurately. Visibly, the application of wavelet and FFT algorithm for power harmonic detection obtain a good effect. This combined algorithm can improve the detection accuracy and the real-time character, at the same time it makes the harmonic detection technology in developing further perfection.