Detection Algorithm For Rural Power Distribution Network Harmonic And Inter-harmonic

Electricity is currently the safest, most environmental protection and the most convenient secondary energy, and has played an increasingly important role in the aspect of accelerating social progress, promoting the development of science and technology and improving people’s living standards. Rural power distribution network is the main part of power system, the stability and security of it directly affects agricultural production and even the entire national economic interests.With the progress of social economy, various kinds of high and new technology into the life of people gradually, the subsequent is various kinds of large equipment into the rural power distribution network. For example, some large number of non-linear and shock loads put into widespread use in the rural power distribution network, makes many power quality problems of power grid. For example, give the rural power distribution network harmonic pollution a serious impact, its emergence is the first safe operation of power will bring difficulties, and the second will bring about the loss of the national economy, so the harmonic pollution detection and effective governance become a research direction of many scholars. On the integer harmonics question many scholars have studied, non-integer harmonics which are mingled with the integer harmonics have been a great difficulty in the harmonic detection and handling problems. So treat rural power distribution network harmonics and inter-harmonics should pay equal attention, they threaten to the rural power distribution network is huge.The premise of governance rural power distribution network harmonics and inter-harmonics is to accurately estimate its parameters, the paper mainly from some algorithm such as Fourier analysis, wavelet analysis and modern spectral estimation analyzing rural power distribution network harmonics and inter-harmonics parameter estimation. Fourier transform is the most basic harmonic and inter-harmonic analysis, and spectrum leakage and fence effect has been the problems when The Fourier transform of signal is not synchronous sampling, and when it is applied, the frequency resolution is inversely proportional to the length of the sampling data. Windowed and interpolation Fourier transform can solve this problem, this paper lists several windowed Fourier transform, and comparative simulation analysis are conducted. From the simulation results can be concluded that there are pros and cons of each window function, there are conflicting on the analysis of the precision and computation, etc. Wavelet transform overcomes the drawback of Fourier transform in the frequency domain localization completely and totally without localized in time domain,, can pick up the signal when the frequency information is also used for harmonic analysis in recent years. But by using wavelet packet decomposition and reconstruction for the signal, there is no big change in the signal, wavelet analysis is compared with Fourier harmonic signal processing, there is no advantage, meditation and spectrum aliasing more serious, analysis precision is not high.On the above research between harmonic and inter-harmonic algorithm shortcoming, paper applies modern spectral estimation algorithm for photovoltaic demonstration plants to field test harmonic and harmonic detection signal. Using modern spectral estimation PM-MUSIC spectral estimation can overcome the Fourier spectrum leakage and other problems, it can accurately highlighted the signal of each harmonic and inter-harmonic frequency estimation. According to the measured data, the Fourier transform and PM-MUSIC spectrum estimation of harmonics and harmonic spectrum distribution were analyzed, it can be concluded that the PM-MUSIC spectrum estimation algorithm can more clearly highlight spectrum situation step by step, is advantageous to the rural power distribution network harmonics power quality harmonic real-time monitoring and analysis, and don’t need synchronous sampling, confirming the modern spectral estimation algorithm is applied to the power grid harmonic and an effective means to detect harmonics.