Detection method for power grid harmonic signal

Abstract

The invention discloses a detection method for a power grid harmonic signal. The detection method comprises the steps of S00, extracting a harmonic signal from a power grid and taking the harmonic signal as an input signal; S10, performing wavelet transform on the input signal; S20, determining a wavelet threshold function, and solving the optimal wavelet threshold; S30, de-noising the input signal after wavelet transform according to the optimal wavelet threshold; and S40, performing EMD harmonic frequency analysis on the denoised signal. According to the detection method for the power grid harmonic signal, EMD harmonic detection is used as a foundation, wavelet self-adaptive threshold denoising is added before detection, the denoised signal can be approximate to a true signal to the greatest extent, so that an improved EMD harmonic detection method is obtained, and the EMD harmonic analysis accuracy can be remarkably improved.

Description

technical field [0001] The invention relates to the technical field of power grid security, in particular to a detection method for a harmonic signal of a power grid. Background technique [0002] Due to the rapid development of new energy access technologies, the access of a large number of nonlinear loads (such as frequency converters, inverters, etc.) has brought huge harmonic pollution to the power grid. A large number of harmonics reduce the power supply and distribution efficiency of the system, increase the loss of electrical equipment, affect the life of the equipment, and may cause the power grid protection system to refuse to operate, malfunction, etc., causing hidden dangers to the user's electricity safety, with serious consequences . [0003] In order to eliminate the influence of harmonics, it is necessary to accurately detect each harmonic component in the signal. At present, researchers at home and abroad have proposed a variety of harmonic detection method...

AI Technical Summary

Problems solved by technology

The denoising method using a hard threshold reduces the influence of noise, but due to the discontinuity of the threshold function, oscillation may occur when the signal is reconstructed, resulting in signal distortion; while the existing method using a combination of soft and hard thresholds, although its continuity It has improved compared with the previous ones, but due to the complexity of the threshold calculation, the calculation takes a long time, the result is difficult to converge, and the quality of the threshold result is unknown

Images