Dynamic compensation method for harmonic current of power grid based on wavelet transformation

Abstract

The invention provides a dynamic compensation method for harmonic current of a power grid based on wavelet transformation. The method comprises the steps of: performing wavelet transformation analysison a sampled power grid current, decomposing power grid current data by adopting a Matllat algorithm, and separating a wavelet coefficient of a fundamental current in the power grid current; selecting three wavelet coefficients with the phase difference of 120 degrees from the wavelet coefficients of the fundamental current, and operating the three wavelet coefficients by utilizing the sine wavephase characteristics to obtain a fundamental current compensation coefficient; reconstructing the wavelet coefficient of the fundamental current, calculating the fundamental current in the power gridcurrent, and compensating the fundamental current by adopting the fundamental current compensation coefficient to obtain a high-precision real-time fundamental current; and subtracting the fundamental wave current from the power grid current to obtain a high-precision harmonic current in the power grid. The dynamic compensation method solves the defect of a poor dynamic performance when the real-time detection of the harmonic current is performed by adopting the wavelet transform, can effectively improve the real-time detection precision of the harmonic current of the wavelet transform powergrid and can improve the dynamic response performance of the harmonic current.

Description

technical field [0001] The invention belongs to the technical field of electric power systems, and in particular relates to a dynamic compensation method for power grid harmonic current based on wavelet transform. [0002] technical background [0003] With the development of society and economy, more and more power electronic devices are applied to the power system. The large application of these nonlinear loads makes the harmonic current in the power grid increase greatly, causing serious harmonic pollution to the power grid. Greatly reduces the power quality. The harmonic current in the power grid brings great harm to the safety and economical operation of the power system. On the one hand, the harmonic current in the power system brings harm to the production and transmission of electric energy, and also affects the normal operation of electronic equipment; on the other hand, the harmonic current also causes a great waste of electric energy and brings environmental pollu...

AI Technical Summary

Problems solved by technology

If the grid current is stable, the periodic expansion of the grid current data can achieve better results, but when the grid current changes, the periodic expansion of the grid current data will cause errors in harmonic current detection and reduce the dynamic detection accuracy , the harmonic detection has a one-period hysteresis

Therefore, in view of the disadvantage of poor dynamic performance of wavelet transform harmonic detection, it is necessary to improve the real-time harmonic detection of wavelet transform to improve its real-time detection accuracy

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