Current alarm signal processing method for improved mathematical morphology filter

Abstract

The invention discloses a current alarm signal processing method for an improved mathematical morphology filter. Pulse and noise interferences are removed by a mathematical morphology method and various frequency spectrum interferences of harmonic waves and the like are removed by a wavelet method, so that a better effect of inhibiting the interferences is obtained and a more pure fundamental wave current is obtained for processing a power alarm signal. The current alarm signal processing method comprises the following steps of: a first step of obtaining current waveform data by utilizing a current transformer and a data acquisition hardware circuit; a second step of carrying out alternate hybrid filtering processing on the current signal by the mathematical morphology method through adopting a cosine structural element so as to filter out the pulse and noise interferences; and a third step of carrying out multi-scale wavelet decomposition on the current signal by adopting a biorthogonal wavelet with a linear phase, selectively reserving low-frequency and high-amplitude wavelet coefficients by setting a threshold value and finally, carrying out signal reconstruction by utilizing the reserved wavelet coefficients so as to remove various frequency spectrum interferences of the harmonic waves and the like and obtain a fundamental wave power signal.

Description

Technical field [0001] The invention relates to a method in the field of power system signal processing, in particular to a current alarm signal processing method with improved mathematical morphology filters, which can be used in the fields of power system current signal measurement, monitoring alarms, and relay protection. Background technique [0002] The current waveform in the normal operation of the power system is a sine wave, the frequency is the fundamental wave (50Hz in China), and the effective value is near the rated value. When the power system fails, the current of the power system will change abnormally. For example, the effective value of the current during a fault will be seriously too large or too small, and there will be many abnormal signals such as harmonics, pulses and noise in the waveform. In order to ensure that an accurate judgment can be made and an alarm message can be issued when the current exceeds the limit, the power alarm system needs to remove t...

AI Technical Summary

Problems solved by technology

[0007] By comparing the two methods of mathematical morphology and wavelet analysis, it can be found that the mathematical morphology method is difficult to select the appropriate structural elements when analyzing a variety of different interference components, thus affecting the filtering effect; although wavelet analysis has better frequency resolution ability, It is better to filter out harmonics, but for pulse interference signals, it will be used as a signal mutation point to strengthen retention, that is, the effect of filtering out pulse interference is not good

Images