The Design And Realization Of Power Harmonic Wave Monitoring And Management System

Along with the demand for automation and networking in State Grid improves,more and more devices related to power electronics and microelectronics are used in Grid widely.Because of these no-linear devices used widespread,the harm of harmonic in power system is increasing.In order to solve the harmonic problem in power system,the research in harmonic suppression has been the important breakthrough to avoid the Grid affected by harmonic.Owing to the harmonic detection technique plays the important role in harmonic suppression,more and more research about how to detect the harmonic information effective and real-timely in harmonic detection area has been carried out.By reading a lot of literatures,this paper firstly summarize the generation and harm of harmonic in power system and do some research in the present situation and shortcomings of harmonic detection in power system.Secondly,this paper outlines the relationship between the Fourier transform,the Wavelet transform and harmonic and analyses how the typical algorithms of the Fourier transform and the Wavelet transform applied in harmonic detection in depth.On the base of mainly discussing the shortcomings of the FFT(Fast Fourier Transform) in detecting the harmonic,this paper using the Mallat algorithm in the Wavelet transform combined with FFT to detect harmonic in power system.During the research process, the results of using Mallat algorithm to detect the harmonic in power system has the phenomenon of aliasing and the weakness of real-time.For overcoming the weaknesses of Mallat algorithm,a optimize algorithm which using FHT(Fast Hadamard Transform) to replace FFT in single-band reconstruction algorithm is proposed.Using Matlab software this optimize algorithm which not only solves the aliasing problem but also improves the real-time was verified.Lastly,in order to offer substantial data support for engineer to improve the efficiency of solving the problem of the harmonic in power system.This paper uses Matlab Builder For Java to combine the Matlat software which is good at computing and J2 EE framework which good at offering networking service based on Java so as to design and develop a monitoring and management system based on Web technology.This management system can monitor the power lines and show the details of the harmonic in power system.