復(fù)雜電力諧波分析方法研究
[Abstract]:Due to the progress of high-power semiconductor devices and their good control ability, more and more nonlinear devices based on power electronics technology have been widely used. However, the harmonic and interharmonic injected into the system also cause many serious problems. Therefore, harmonic management is urgent. High precision harmonic analysis is the precondition of harmonic control. Fast Fourier transform (FFT) is the most effective and fast method for harmonic analysis. However, FFT needs synchronous sampling, and there are the effects of aliasing, truncation and fence effect, which will affect the accuracy of parameter estimation, especially when the interharmonic analysis is done. In addition, the resolution of FFT is also very low, how to break through the resolution limit of FFT will be an important problem in interharmonic analysis. In this paper, the above problems are expanded, and how to improve the accuracy and reliability of parameter estimation is discussed in detail. The main results are as follows: (1) an energy center of gravity method considering spectrum leakage is proposed. In order to reduce the error caused by spectral interference in the energy barycenter method, the iterative process is introduced to modify the amplitude of the spectrum in the process of the energy center of gravity method. The initial value of the iteration can be obtained by the energy center of gravity method. The iterative process is to subtract the values of the positive and negative frequency spectrum leakage from the results of the FFT, and then repeat the energy center of gravity method. The termination of the iterative process depends on the iterative error defined in the time domain. Simulation results show that the proposed algorithm has good estimation accuracy for weak signals, low iteration times and low computational cost, so it is a practical method. (2) A harmonic parameter estimation method based on information theory and MUSIC algorithm is proposed. Firstly, the information theory (AIC criterion, MDL criterion) and canonical correlation technique are used to estimate the sinusoidal fraction. Through simulation analysis and comparison, this paper uses MDL criterion to estimate sinusoidal fraction in subsequent simulation. After estimating the sinusoidal fraction correctly, this chapter proposes to use the MUSIC algorithm in spatial spectrum estimation for harmonic estimation. By comparing the same complex power signal with Burg algorithm, the MUSIC algorithm can estimate harmonics more accurately. (3) A ESPRIT harmonic analysis method with high accuracy for sinusoidal fraction estimation is proposed. In this method, the frequency fraction of the signal is estimated by the RD curve, and then the frequency, amplitude and phase are estimated by the ESPRIT algorithm. Simulation results show that the harmonic estimation method based on this method not only has high accuracy and high resolution in short data, but also has good robustness.
【學(xué)位授予單位】:中國礦業(yè)大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2014
【分類號】:TM935
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