CN108872681B - An Optical Current Transformer Based on Strip Radial Polarization Grating - Google Patents

Abstract

The invention relates to an optical current transformer based on a strip-shaped radial polarization grating, comprising a magnetic collecting ring, a light source, a first magnetic conducting plate, a second magnetic conducting plate, a CCD image sensor, a polarizer, a magneto-optical film and a strip-shaped radial polarization grating; the magnetic collecting ring is arranged on the outside of the bus bar; the magnetic collecting ring is provided with an opening, and the opening is provided with a first magnetic conducting plate and a second magnetic conducting plate in parallel; the first magnetic conducting plate A light source is arranged on the upper side of the plate; a CCD image sensor is arranged on the lower side of the second magnetic conductive plate; a polarizer, a magneto-optical device are arranged between the first magnetic conductive plate and the second magnetic conductive plate from top to bottom in sequence. Thin film and radial polarization grating; the first magnetic conductive plate and the second magnetic conductive plate are provided with through holes for the light path to pass through. The detection of the optical current transformer of the present invention is independent of optical power, has linear measurement and has a large measurement range.

Description

An Optical Current Transformer Based on Strip Radial Polarization Grating

technical field

The invention belongs to the technical field of electric power system current measurement, and in particular relates to an optical current transformer realized based on a strip-shaped radial polarization grating.

Background technique

Optical current transformers use optical sensing technology, which has the advantages of good insulation performance, strong anti-interference ability, no transient magnetic saturation, and digitalization, which meets the development needs of smart grids. The basic principle of the optical current transformer is based on the Faraday magneto-optical effect, that is, when linearly polarized light passes through the magneto-optical material under the action of an external magnetic field parallel to its propagation direction, its polarization plane will rotate, and the angle of rotation is proportional to the magnitude of the current. . Existing detection modes cannot directly and linearly measure the rotation angle, but use the polarized light intensity demodulation mode for indirect measurement. This measurement method has the following problems (1) Optical power correlation. The fluctuation of light source, transmission loss, fiber aging, angle error of polarizer and analyzer, photoelectric conversion and analog-to-digital conversion error and other factors directly affect the measurement results. (2) Nonlinear measurement. The Faraday magneto-optical rotation angle needs to be controlled within a small angle (less than 1 degree) to achieve approximate linearity, resulting in a small dynamic measurement range. (3) The problem of temperature drift. The temperature drift of light sources, optical devices, photoelectric conversion devices and electronic devices directly affects the magnitude of the outgoing light intensity, resulting in measurement errors.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide an optical current transformer based on a strip-shaped radial polarization grating, which realizes the detection mode independent of optical power, linear measurement and large measurement range.

To achieve the above object, the present invention adopts the following technical solutions:

An optical current transformer based on a strip-shaped radial polarization grating is characterized in that it includes a magnetic collecting ring, a light source, a first magnetic conductive plate, a second magnetic conductive plate, an optical path, a CCD image sensor, a polarizer, a magnetic Optical film and strip-shaped radial polarization grating; the magnetic collecting ring is arranged on the outside of the bus bar; the magnetic collecting ring is provided with an opening, and the opening is provided with a first magnetic conducting plate and a second magnetic conducting plate in parallel; A light source is arranged on the upper side of a magnetic conductive plate; a CCD image sensor is arranged on the lower side of the second magnetic conductive plate; polarizers are arranged between the first magnetic conductive plate and the second magnetic conductive plate from top to bottom. , a magneto-optical film and a strip-shaped radial polarization grating; the first and second magnetic conductive plates are provided with through holes for the passage of light paths.

Further, the light source and the CCD image sensor are arranged symmetrically with the opening centerline as the axis;

Further, the following steps are included:

Step S1: the busbar is energized, and the magnetic collecting ring forms a uniform magnetic field between the first magnetic conductive plate and the second magnetic conductive plate;

Step S2: the laser light emitted by the light source obtains linearly polarized light through a polarizer;

Step S3: the linearly polarized light passes through the magneto-optical film, and the plane of polarization rotates, enters the strip-shaped radial polarization grating to form a strip-shaped light spot and is input to the CCD image sensor;

Step S3: when the external magnetic field changes, the strip light spot is displaced synchronously, and the original intensity distribution is maintained;

Step S4: The CCD image sensor analyzes and processes the light intensity image to obtain the position of the maximum or minimum light intensity, calculates the displacement of the light spot, and obtains the current value to be measured.

Further, the linearly polarized light passing through the magneto-optical film generates a Faraday magneto-rotation angle under the action of a magnetic field, and its magnitude is proportional to the current to be measured, and the strip-shaped radial polarization grating converts the linearly polarized light passing through the magneto-optical film into light. Strong distribution image. The linearly polarized light that is consistent with a certain vibration transmission direction on the strip radially polarized grating can pass through the grating, while the linearly polarized light perpendicular to the vibration transmission direction cannot pass through the grating. The transmitted light intensity in the area decreases from the maximum to the minimum, forming a strip-shaped light spot with a fixed shape. The CCD image sensor is used to locate the light spot image passing through the grating to obtain the Faraday magneto-rotation angle and the current value to be measured.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention has no correlation with optical power, and the measurement result is more accurate.

2. The present invention realizes linear measurement and has a larger measurement range.

Description of drawings

Fig. 1 is the principle diagram of the present invention;

2 is a schematic diagram of a strip-shaped radial polarization grating in an embodiment of the present invention;

In the figure: 1-bus bar, 2-magnetic collecting ring, 3-light source, 4-first magnetic conductive plate, 5-second magnetic conductive plate, 6-optical path, 7-CCD image sensor, 8-polarizer, 9 - Magneto-optic thin film, 10-stripe radial polarization grating.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Referring to FIG. 1 , the present invention provides an optical current transformer based on a strip-shaped radial polarization grating, which is characterized in that it includes a magnetic collecting ring 2 , a light source 3 , a first magnetic conducting plate 4 , and a second magnetic conducting plate 5 . , optical path 6, CCD image sensor 7, polarizer 8, magneto-optical film 9 and radial polarization grating 10; the magnetic collecting ring 2 is arranged on the outside of the bus bar 1; the magnetic collecting ring 2 is provided with an opening, the The opening is provided with a first magnetic conducting plate 4 and a second magnetic conducting plate 5 in parallel; a light source 3 is arranged on the upper side of the first magnetic conducting plate 4; a CCD image sensor 7 is arranged on the lower side of the second magnetic conducting plate 5; A polarizer 8, a magneto-optical film 9 and a radially polarizing grating 10 are sequentially arranged between the first magnetic conducting plate 4 and the second magnetic conducting plate 5 from top to bottom; The second magnetic conducting plate 5 is provided with a through hole for the light path 6 to pass through.

In an embodiment of the present invention, the bus bar 1 conducts current, and the magnetic collecting ring 2 forms a uniform magnetic field between the first magnetic conducting plate 4 and the second magnetic conducting plate 5 . The laser light emitted from the light source 3 passes through the polarizer 8 to obtain linearly polarized light. The linearly polarized light passes through the magneto-optical film 9, the polarization plane rotates, and enters the strip-shaped radial polarization grating 10 to form a strip-shaped light spot. The strip-shaped radial polarization grating structure is shown in FIG. 2 . When the applied magnetic field changes, the strip light spot is displaced synchronously and maintains the original intensity distribution. The position of the maximum or minimum light intensity is obtained by analyzing and processing the light intensity image by the CCD image sensor 7, the displacement of the light spot is calculated, and the current value to be measured is obtained. This measurement method realizes the linear measurement of current and is independent of optical power.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (2)

1. The utility model provides an optical current transformer based on bar radial polarization grating realizes which characterized in that: the device comprises a magnetic collecting ring, a light source, a first magnetic conduction plate, a second magnetic conduction plate, a CCD image sensor, a polarizer, a magneto-optical film and a strip-shaped radial polarization grating; the magnetic collecting ring is arranged on the outer side of the bus; the magnetic collecting ring is provided with an opening, and a first magnetic conduction plate and a second magnetic conduction plate are arranged in parallel in the opening; a light source is arranged on the upper side of the first magnetic conduction plate; a CCD image sensor is arranged on the lower side of the second magnetic conduction plate; the light source and the CCD image sensor are symmetrically arranged by taking the opening center line as an axis.

2. The working method of the optical current transformer based on the strip-shaped radial polarization grating implementation is characterized by comprising the following steps of:

step S1, current is supplied to the bus, and the magnetism collecting ring forms a uniform magnetic field between the first magnetic conduction plate and the second magnetic conduction plate;

step S2, the laser emitted by the light source passes through a polarizer to obtain linearly polarized light;

step S3, linearly polarized light passes through the magneto-optical film, the polarization plane rotates, enters the strip-shaped radial polarization grating to form strip-shaped light spots and is input to the CCD image sensor;

step S4, when the external magnetic field changes, the strip-shaped light spots synchronously shift and keep the original intensity distribution;

and step S5, analyzing and processing the light intensity image by the CCD image sensor to obtain the position of the maximum or minimum light intensity, and calculating the light spot displacement to obtain the current value to be measured.

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