All-fiber current transformer open loop signal detection method and apparatus thereof

Abstract

The invention discloses an all-fiber current transformer open loop signal detection method which comprises the following steps: employing an asymmetric square wave with a period of 2t and an amplitude of Vpi / 2 as a modulation signal, carrying out phase modulation on an optical signal, wherein the t is a transit time of the all-fiber current transformer; after the optical signal after phase modulation is subjected to interference, converting the optical signal into an electric signal; subjecting the electric signal to a sampling treatment; in a period 2t, calculating difference between sampling sum of electric signal positive half cycle and sampling sum of electric signal negative half cycle, defining a difference result as S1, defining sampling sum of the electric signal as S2, dividing S1 by S2, and defining a divide resultant as an open loop signal detection result of the all-fiber current transformer. An embodiment of the invention also discloses an all-fiber current transformer open loop detection apparatus. Since the asymmetric square wave is employed as a modulation signal, in a demodulation process, factors related to light source power and circuit gain in an interference output result are eliminated through a specific algorithm, thus the open loop signal detection result is only related to Faraday phase shift, and accuracy of a measuring result is raised.

Description

technical field [0001] The invention relates to the technical field of optoelectronics, in particular to an open-loop signal detection method and device of an all-fiber-optic current transformer. Background technique [0002] The all-fiber current transformer is a new type of current sensing device based on the Faraday effect and using optical fibers as sensitive and conductive elements. The structure of the all-fiber-optic current transformer is as follows: figure 1 As shown, its working principle is as follows: the light emitted by the light source is polarized by the fiber polarizer after passing through the circulator and becomes linearly polarized light; the pigtail of the above optical polarizer and the pigtail of the phase modulator are welded at 45°, The polarization-maintaining fiber injected into the fiber polarizer at 45° is decomposed into two beams of linearly polarized light in orthogonal modes, which are transmitted along the X-axis and Y-axis of the polariza...

AI Technical Summary

Problems solved by technology

The fluctuation of light output power of the light source and the drift of the gain of the signal detection circuit will cause the transformation ratio error, thereby reducing the measurement accuracy of the all-fiber current transformer

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