Method for analyzing harmonics of power system by adopting Hilbert-Huang transform (HHT)

Abstract

The invention discloses a method for analyzing harmonics of a power system by adopting Hilbert-Huang transform (HHT), and belongs to the technical field of power quality analysis of power systems. According to the technical scheme, the capable of obtaining integral mode function components of an original signal by adopting HHT comprises the following steps of: obtaining each mode function component of the original signal of a power signal by adopting HHT, judging whether mode mixing exists or not, separating the mode-mixed part of the original signal of the power signal from the original signal, sequentially performing Fourier transform and filtration on an analysis signal, performing HHT on the filtered signal to obtain each mode function component of the analysis signal, and integrating mode function components without mode mixing and each mode function component of the analysis signal to obtain the integral mode function components of the original signal. The method is applied to an electric power sector.

Description

technical field [0001] The invention adopts a power system harmonic analysis method of HHT, and belongs to the technical field of power system power quality analysis. Background technique [0002] In 1998, Huang et al. proposed a new time series signal analysis method - HHT (Hilbert-Huang Transform), which is a major breakthrough in the analysis of linear and steady-state spectrum based on Fourier transform. It is an analysis method for nonlinear and non-stationary signals. [0003] HHT consists of two processes: first, the signal is decomposed into finite intrinsic mode function (IMF) components by empirical mode decomposition (EMD), and then the IMF is subjected to Hilbert transform to obtain the instantaneous frequency and instantaneous Amplitude; EMD is the core process of HHT, because only the Hilbert transform is performed on the IMF after EMD, and the instantaneous frequency and instantaneous amplitude obtained have physical meaning. [0004] EMD has the problem of ...

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Problems solved by technology

[0004] EMD has the problem of modal mixing in practical applications. When the frequency of the two component components in the signal is within 2 times the frequency, EMD cannot decompose it; DEERING R and KAISER J F published "The use of A masking signal to improve empirical mode decomposition" proposed the masking signal EMD method, but the selection of two parameters to construct the masking signal is difficult, which affects the further promotion of the method; SENROY N and SURYANARAYANAN S published "Two techniques to enhance The frequency heterodyne EMD method was proposed in "empirical mode decomposition for power quality applications". However, due to the error and boundary effects of EMD decomposition, pseudo-mode components will be generated in the low frequency band. After frequency heterodyne, these pseudo-mode components will be reversed to high The frequency components are mixed together with the real high frequency components and it is difficult to distinguish; therefore, on the basis of existing methods, it is a hot and difficult point in the current research to use HHT to accurately analyze the harmonics of the power system.

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