Reflecting type full-optical fiber current sensor

Abstract

The invention discloses a reflective all-optical fiber current sensor, which is characterized in that a sagnac interference system which consists of a polarization maintaining optical fiber coupler adopts two 1 / 4 wave plates and a Faraday rotator as the phase bias of light waves and adopts a single polarization maintaining optical cable as a transmission line and the reflective end surface of an optical fiber sensing ring to commonly form the reflective sensing system. An interference optical circuit further adopts a polarization multiplexer, one port thereof is welded by 90 degrees, and two polarizers are additionally added at the port of the polarization maintaining optical fiber coupler, thereby eliminating the polarization noise of a plurality of devices during the polarization transformation and the transmission. The reflective all-optical fiber current sensor with the optical circuit structure has stable light wave phase bias. Interference signals have very high signal-to-noise ratio. The circuit processed by electric signals is greatly simplified. Therefore, the phase delay generated by the circuit which is processed by the electric signals is very small. The angular difference of an actual electronic current transformer which is composed by the reflective all-optical fiber current sensor can achieve the national 0.1 level standard.

Description

technical field [0001] The invention relates to a current sensor, in particular to a reflective all-optical fiber current sensor used for measuring large current and carrying out relay protection in high-voltage lines. Background technique [0002] In order to reduce the transmission loss in long-distance power transmission, increasing the transmission voltage is an effective way. At present, current transformers composed of silicon steel sheets and enamelled copper wires are used for current measurement and relay protection in high-voltage lines. As the line voltage continues to increase, this current transformer encounters great difficulties in insulation. The quartz material used to make optical fibers is itself a good insulator. Therefore, the current transformer made of optical fiber can theoretically be used at any high voltage, and is an ideal substitute for the currently used current transformer. [0003] When the current flows in the conductor, a magnetic field w...

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Problems solved by technology

However, since the 1 / 4 wave plate and the induction fiber coil are by no means ideal polarized light components, there is still a small amount of residual polarized light in the X direction when the polarized light in the X direction is converted into the polarized light in the Y direction and returned, and the polarized light in the Y direction is also converted When polarizing light in the X direction, there will still be a small amount of residual polarized light in the Y direction. When these two parts of the residual polarized light are transmitted back through the fiber polarizer for interference, certain polarization noise will be generated, which will affect the measurement accuracy of the transformer.

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