All optical-fiber current sensor based on magnetic fluid and multi-mode interference and detection method

Abstract

The invention discloses an all optical-fiber current sensor based on magnetic fluid and a multi-mode interference structure. The all optical-fiber current sensor comprises a signal detection unit and a sensing unit. The signal detection unit comprises an SLD light source, a 50:50 optical fiber beam splitter, an adjustable optical fiber attenuator, a photoelectric balance detector, a data collection card, a computer, a power-on coil and a programmable power source. The sensing unit comprises a multi-mode coreless optical fiber arranged in a quartz capillary tube, the portion between the quartz capillary tube and the multi-mode coreless optical fiber is filled with magnetic fluid, the two ends of the multi-mode coreless optical fiber are respectively connected with single-mode input and output optical fibers in a welding mode, and the two ends of the quartz capillary tube are sealed by optical solidification glue. According to the all optical-fiber current sensor based on magnetic fluid and the multi-mode interference structure, the sensitivity of the magnetic field generated by the magnetic fluid to the currents and the multi-mode interference theory are used, the change relation between light intensity and currents is directly detected and output to achieve the purpose of detecting currents, and the defect that the polarized light detection method adopted by a traditional all optical-fiber current sensor is not stable is overcome.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to an all-fiber current sensor based on magnetic fluid and multimode interference. Background technique [0002] With the continuous improvement of the grid voltage level and capacity in the power system, higher requirements are placed on the current transformer. The traditional electromagnetic current transformer has gradually exposed serious defects, mainly including: (1) When the system is short-circuited and the current increases abnormally, the core of the transformer is seriously saturated, the measurement dynamic range is limited, and the transient performance deteriorates. The secondary current cannot correctly reflect the primary current, causing the relay protection to refuse to operate or malfunction; (2) The transient signal and harmonic measurement capabilities are poor, and its linearity and dynamic characteristics cannot meet the requirements of fast fault respons...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the disadvantages of existing all-fiber current sensors that are susceptible to birefringence and Sagnac effects, the present invention provides a novel all-fiber current sensor based on magnetic fluid and multi-mode interference, which utilizes the sensitivity of magnetic fluid to the magnetic field generated by current And multi-mode interference theory, combined with the dual optical path heterodyne detection method, overcomes the instability defect of the traditional all-fiber current sensor using polarized light detection method

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