Method for analyzing random error characteristic of optical fiber current transformer based on total variance

Abstract

Provided is a method for analyzing the random error characteristic of an optical fiber current transformer based on total variance. The method comprises the steps as follows: collecting a current signal of an optical fiber current transformer through serial output to get observation data; eliminating outliers from the observation data based on the Letts criterion, carrying out zero-mean, trend term and standardization processing on the data; testing the stability, periodicity and normality of the data after processing to get a stable, normal and zero-mean data sequence; working out the variance of the data sequence through a total variance approach; and finally, carrying out double logarithm curve fitting of the total variance (Sigma<Atol><2>) and the related time (Tau) based on the random error source variance sum-of-squares relation, namely, Sigma<Atol><2>=(R<2>*Tau<2>) / 2+(K<2>*Tau) / 3+B<2>*(2 / Pi)*In2+N<2> / Tau+3*Q<2> / Tao<2>, to extract five random error coefficients in the current information of the optical fiber current transformer. By using the method, the random error characteristic of an optical fiber current transformer can be analyzed more accurately, the defect of the traditional Allan variance method that the estimated value fluctuates greatly is solved effectively, and a guide can be provided for performance design and random error compensation of optical fiber current transformers.

Description

technical field [0001] The invention relates to the field of error analysis of current transformers, in particular to a method for analyzing random error characteristics of optical fiber current transformers based on total variance. Background technique [0002] Optical fiber current transformer is an important process layer equipment in smart substation, which provides current and voltage information for smart substation bay layer equipment, and realizes functions such as power system relay protection, electric energy metering, fault recording, and status monitoring. Optical fiber current transformers realize real-time measurement and monitoring of current signals, and provide input signals for power system relay protection, electric energy metering and other equipment. The random error of the fiber optic current transformer has an important impact on its performance accuracy, so higher requirements are put forward for the analysis of its random error characteristics. The ...

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Problems solved by technology

In view of the fact that there is a basic leakage phenomenon in the transfer function of Allan’s variance, the estimated value of the variance is insufficient to oscillate violently when the correlation time is close to half of the total measurement duration, and the confidence level is low, so it can only effectively analyze ideal time-varying and stationary signals, and cannot Accurately characterize the variance fluctuation of non-stationary signals in different frequency ranges

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