Improved harmonic detection method for double-feed wind power generation system

Abstract

The invention discloses an improved harmonic detection method for a double-feed wind power generation system, and the method comprises the steps: sampling current signals, comprising harmonic waves, in the double-feed wind power system at different wind speeds and under wind conditions; 2), continuously adjusting the threshold parameters of wavelet denoising according to the fractal dimensions ofa harmonic wave signal, and removing noise in a segmented manner through wavelet transformation; 3), enabling the denoised signal to pass through a high-pass digital filter based on a Chebyshev type I, carrying out the EMD decomposition of the harmonic through an improved EMD method, carrying out the Hilbert transformation of each IMF component, and detecting the harmonic component at each order in a harmonic signal of a wind power plant. The method provided by the invention is used for the harmonic analysis of the double-feed wind power generation system, can achieve the accurate detection ofthe harmonic component at each order in the harmonic signal of the wind power plant, also can achieve the reflection of a moment of the abrupt change of the harmonic signal, and enables the decomposition result of the harmonic signal to be more accurate.

Description

technical field [0001] The invention belongs to the field of harmonic detection, in particular to an improved harmonic detection method of a double-fed wind power generation system. Background technique [0002] With its unique advantages, wind power technology is developing at an unprecedented speed. However, doubly-fed wind turbines use high-power AC-DC-AC converters and operate under changing wind speeds, which will generate a large number of harmonic currents, which seriously threaten the safe, stable and economical operation of the power system. Therefore, the wind turbines in the wind power system It is important to detect harmonic currents injected into the common connection point. [0003] Since the harmonic signal obtained from the wind farm is a non-stationary, nonlinear signal and contains a lot of noise signals, it cannot be directly used for harmonic detection. In order to improve the detection accuracy, the signal needs to be denoised. Signal denoising is one...

AI Technical Summary

Problems solved by technology

These methods have their own advantages and disadvantages, and the scope of use is also limited.

For the harmonics with the characteristics of randomness and non-stationarity in the wind power generation system, the traditional harmonic detection methods have different degrees of limitations in the analysis, and the harmonic detection method based on Hilbert-Huang transform The detection of stable signals is very suitable for the detection of current signals containing harmonics in wind power systems, but there are still some defects in envelope fitting and modal mixing, which need further improvement

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