KR20060005199A - Optical potential transformer interleaved detector - Google Patents

Abstract

The present invention relates to a detector-embedded photovoltaic detector. In the related art, a separate component other than the sensor and the signal processor is used by applying an electric field to a Pockels element using a voltage divider, and thus, the ultra-light weight characteristic of the optical sensor is eliminated. However, there is a problem in that precision is lowered due to an electric field inequality generated when a voltage is applied. In view of the above problems, the present invention provides a light emitting device comprising: a first polarizer for polarizing and outputting only light vibrating in a vertical direction from laser incident light; 1/4 wavelength for generating circularly polarized light by separating light oscillating in the vertical direction from the first polarizer into vertical and horizontal coordinate components, and horizontally delaying the horizontal coordinate component by 90 degrees. Plate; According to the intensity of the applied electric field, Pockels outputs the elliptical polarization of the incident light from the quarter-wave plate by varying the optical refractive index of the incident light and the vertical refractive light component to generate a phase delay. An element; A first voltage detector installed opposite to a high voltage measurement object and configured to output a voltage proportional to the high voltage of the measurement object; A second voltage detector provided opposite to the ground potential of the measurement target of the high voltage and made of a metal plate for outputting a voltage proportional to the voltage of the ground potential; An electrode film coated on both ends of the Pockels element in a longitudinal direction and configured to apply voltages from the first and second voltage detectors to both ends of the Pockels element; It includes a lead wire made of an electrical conductor for transferring the voltages from the first and second voltage detectors to the electrode film. By using a voltage detector, a high amplification voltage is applied to the Pockels element to improve reliability of voltage measurement. In this case, the space occupied by the sensor can be reduced, thereby simplifying the installation.

Description

Detector-type optical voltage detector {OPTICAL POTENTIAL TRANSFORMER INTERLEAVED DETECTOR}

1 is an exemplary view showing a configuration of a conventional optical voltage detector.

2 is an exemplary view illustrating a driving principle of the photovoltage detector of FIG. 1.

3 is an exemplary view showing the configuration of a detector-insertable photovoltage detector according to an embodiment of the present invention.

4 is an exemplary view for explaining a driving principle of the detector-embedded photovoltage detector of FIG. 3.

** Description of the symbols for the main parts of the drawings **

31: first voltage detector 33: voltage transmission lead wire

34: coating electrode film

The present invention relates to a detector-embedded photovoltaic detector, and more particularly, to a detector-embedded photovoltaic detector which makes it possible to improve the measurement sensitivity in an optical voltage detector for detecting voltage using an optical element.

In conventional power equipment, a voltage detection transformer (PT) and a current transformer (CT) composed of iron cores and cores measure high voltages and large currents, but they are large in size and vulnerable to interference due to noise. .

In order to make up for these drawbacks, high voltage and high current measurements using laser light have attracted attention. The high voltage and high current measurement using laser light consists of an insulator, a non-contact method, and its small size makes installation simple and eliminates the influence of surrounding electromagnetic fields. In addition, since the high potential of the primary side is not output to the secondary side, reliability can be improved, and measurement can be performed in a wide frequency range ranging from direct current to several high frequencies.

Attempts have been made to apply new methods to optical elements, structures, and the like for voltage and current measurement sensors using laser light. Various types of optical devices are presented for the current measuring device, but the Pockels element must be used for the voltage measuring device. However, in order to measure voltage with the Pockels device itself, the output sensitivity of the device itself is greatly affected. Thus, new detection devices are needed to achieve higher output sensitivity.

1 is an exemplary view showing a configuration of a conventional optical instrument transformer, as shown in the first polarizer 11 for injecting light oscillating in the vertical direction from the input light to the quarter wave plate 12; A Pockels element (13) which outputs elliptical polarization by generating different phase delays according to the electric field of the light oscillating in the vertical direction; A voltage divider (20) for applying an electric field to the Pockels element (13); The second polarizer 14 filters and outputs only the light components vertically polarized from the output light of the Pockels element 13.

The electro-optic effect is a phenomenon in which the optical crystal is polarized by the change of the refractive index and the azimuth angle in the electric field. Photovoltaic transformers use Pockels elements with electro-optic effects. The Pockels device has an X-direction (fast axis) and a Y-direction (slow axis) as axes for forming a crystal.

When an electric field is applied to the Pockels device, the components having the same refractive index change, causing a difference in the refractive index in each axial direction. The light passing through the Pockels device will vary in speed as it passes through the device as the refractive index changes. That is, Z-axis vibration component light passing through the X axis passes through the element faster than Y-axis vibration component light.

If t = 0㎱, the magnitude of the X-axis vibration light is 1, and the Y-axis vibration light is 1, and when t = 1㎱, the magnitude of the X-axis vibration light is 0.5; Suppose that a light with a magnitude of 0 and a Y-axis oscillation light takes 1 ms of passing time through the X axis and 2 ms of passing through the Y axis with a refractive index change caused by an arbitrary electric field when it is input to the Pockels element. . After 2 ms, the magnitude of the light output from the Pockels element becomes 0.5 magnitude of the X-axis vibration light and 0 magnitude of the Y-axis vibration light. Therefore, the photometer transformer utilizes a phenomenon in which phase delay occurs in comparison with a reference signal because the light passing through the device is proportional to the refractive index according to the change in the refractive index of the Pockels device.

FIG. 2 is an exemplary view illustrating a driving principle of the photovoltaic transformer of FIG. 1, and as shown therein, incident light A is input to the first polarizer 11 to provide a quarter wave plate 12 and Pockels. Via the element 13, a high voltage is applied around the photometer transformer and an electric field C is applied in parallel to the Pockels element 13, and the output of the photometer transformer passes the second polarizer 14. Explain the output.

The unpolarized input light 21 is incident on the first polarizer and only components 22 oscillating in the vertical direction are incident on the quarter-wave plate among the components traveling in the direction parallel to the electric field direction. The quarter wave plate delays the light vibrating in the X-axis direction by 90 ° when there is light vibrating in the X-axis among the light vibrating in the X-axis and the light vibrating in the Y-axis.

If the light propagating while vibrating on the Y axis proceeds in the form of a sine wave, the X-axis light delayed by 90 ° proceeds as a cosine wave. Therefore, the combination 23 of the two lights becomes circularly polarized light. The circularly polarized light 23 is incident on the Pockels device and the refractive indexes of the Pockels device's X and Y axes change according to the electric field applied to the Pockels device. This results in different phase delays for the X-axis oscillating light passing through each axis and the Y-axis oscillating light. The output light 24 passing through the Pockels element becomes elliptical polarization. The second polarizer filters only the vertically polarized light components 25 so that the voltage can be calculated with the applied electric field.

In the method using a voltage divider for applying an electric field to the Pockels device, as shown in FIG. 1, a voltage of a system is applied across the voltage divider 20 and a voltage divided by a predetermined ratio is applied to the Pockels device 13. to be. When the divided voltage is applied across the Pockels element, the magnitude of the electric field becomes E = V / d (V: voltage applied by dividing, d: length of the Pockels element) according to the length of the element.

 However, in the prior art as described above, the photometer transformer measures the voltage by the magnitude of the electric field applied across the Pockels element, so the sensitivity of the Pockels element, the magnitude of the electric field, and the uniformity of the electric field distribution are important. Therefore, while focusing on using a device having excellent sensitivity in the past, the Pockels device having such characteristics has a problem that can only be measured experimentally because it reacts temperature sensitive.

In addition, current products such as power equipment, where the ambient temperature is different from room temperature, but most of the photovoltaic transformers apply electric fields to the Pockels element using a voltage divider for use in an environment where temperature changes are severe. However, when the voltage divider is used, separate parts other than the sensor and the signal processor are used, and thus, the smallest and lightest characteristic of the optical sensor disappears, and the precision is degraded due to the electric field inequality generated when the voltage is applied.

Accordingly, the present invention has been made in view of the above-mentioned problems, and the detector-insertable photovoltaic transformer which can improve the accuracy of voltage measurement by applying an equal electric field to the Pockels element by coating an electrode film on both ends of the Pockels element. The purpose is to provide.

The present invention for achieving the above object, and a first polarizer for polarizing and outputting only the light oscillating in the vertical direction from the laser incident light;

1/4 to generate circular polarized light by separating the light vibrating in the vertical direction from the first polarizer into vertical and horizontal coordinate components, and outputting the composite signal by phase-delaying the horizontal coordinate component by 90 degrees. A wave plate;

According to the intensity of the applied electric field, Pockels outputs the elliptical polarization of the incident light from the quarter-wave plate by varying the optical refractive index of the incident light and the vertical refractive light component to generate a phase delay. An element;

A first voltage detector installed opposite to a high voltage measurement object and configured to output a voltage proportional to the high voltage of the measurement object;

A second voltage detector provided opposite to the ground potential of the measurement target of the high voltage and made of a metal plate for outputting a voltage proportional to the voltage of the ground potential;

An electrode film coated on both ends of the Pockels element in a longitudinal direction and configured to apply voltages from the first and second voltage detectors to both ends of the Pockels element;

And a lead wire made of an electrical conductor for transferring the voltage from the first and second voltage detectors to the electrode film.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is an exemplary view showing a configuration of a detector-insertable photovoltage detector according to an exemplary embodiment of the present invention. As shown in FIG. 3, a first polarizer 11 for polarizing and outputting only light vibrating in the vertical direction from the incident light A is shown. Wow;

The light vibrating in the vertical direction from the first polarizer 11 is separated into a vertical coordinate component (Y component light) and a horizontal coordinate component (X component light), and the horizontal coordinate component (X component light) is 90 degrees. A phase-delayed plate (12) for generating and outputting circularly polarized light by synthesizing and outputting it to the vertical coordinate component (Y component light) again with phase delay;

According to the intensity of the applied electric field, Pockels outputs the elliptical polarization of the incident light from the quarter-wave plate by varying the optical refractive index of the incident light and the vertical refractive light component to generate a phase delay. An element 13;

A first voltage detection unit 31 provided opposite to a measurement target of high voltage (symbol 41 in FIG. 4) and made of a metal plate for outputting a voltage proportional to the high voltage of the measurement target;

A second voltage detector 32 provided opposite to the ground potential portion 42 of the measurement target 41 of the high voltage and made of a metal plate for outputting a voltage proportional to the voltage of the ground potential portion 42;

An electrode film 34 coated on both ends of the Pockels element 13 in the longitudinal direction and applying voltages from the first and second voltage detectors 31 and 32 to both ends of the Pockels element 13; )and;

And a lead wire 33 made of an electrical conductor for transferring the voltages from the first and second voltage detectors 31 and 32 to the electrode film 34. A voltage transfer lead wire 33 for transferring a voltage of the voltage detectors 31 and 32; The coating electrode film 34 transmits a voltage applied to the voltage transmission lead 33 to both ends of the Pockels element and applies an equal electric field to the Pockels element. When installing the detector-embedded type photovoltage detector according to the present invention inside a power device to be measured voltage, the photovoltage detector is a conductor of the power device to which the high voltage is applied and the enclosure of the power device grounded. When the first voltage detector 31 faces the conductor of the power device to be measured and the second voltage detector 32 faces the ground 42 of the power device to be measured in the direction of application of the electric field. do. The electric field of the power device to be measured voltage is applied to the optical voltage detector.

4 is an exemplary view illustrating a driving principle of the detector-insertable photometer transformer of FIG. 3.

The first voltage detector 31 is provided to face the conductor portion 41 of the voltage measurement target to which the high voltage is applied, and the second voltage detector 32 is a ground portion 42 such as an enclosure of the power device to be measured voltage. Install opposite.

The voltage transmission lead 33 connects the first and second voltage detectors 31 and 32 to the upper and lower coating electrode layers 34 of the Pockels element, respectively. The voltages of the first and second voltage detectors 31 and 32 are transferred to the coating electrode film 34 by the voltage transmission lead 33.

If the primary voltage is V and the distance between the primary conductor and the ground is d, the magnitude E of the electric field generated between the primary conductor and the ground on which the photovoltaic transformer is installed is expressed by Equation 1. At this time, the direction of the electric field is directed from the primary conductor to the ground.

When the first and second voltage detectors 31 and 32 are installed, the voltage V ₁ detected at both ends of the first and second voltage detectors 31 and 32 is represented by Equation 2 below.

Where d ₁ is the distance between the voltage detectors.

The voltage detected at both ends of the first and second voltage detectors 31 and 32 is applied between the electrode films 34 coated at both ends of the Pockels element 13 through the voltage transmission lead 33. At this time, the electric field E ₁ generated by the voltage applied from both ends of the first and second voltage detectors 31 and 32 across the Pockels element 13 is expressed by Equation 3 below.

Here, d ₂ is the length of the Pockels element 13.

Therefore, the magnitude of the electric field applied to both ends of the Pockels element 13 is determined from the electric field generated between the conductor portion 41 and the ground portion 42 and the first and second voltage detectors 31 and 32. The sum of the magnitudes of the electric fields generated by the voltage applied across the Pockels element 13 is expressed by Equation 4.

E is an electric field applied to both ends of the Pockels element 13 when the first and second voltage detectors 31 and 32 are not used, and E _total is the first and second voltage detectors 31 and 32. Is the electric field applied across the Pockels element (13). As a result of installing the electric field detectors, i.e., the first and second voltage detectors 31 and 32, inside the photovoltage detector, the Pockels voltage value (field) amplified by (1 + d ₁ / d ₂ ) without using a voltage divider is used. It can be applied to the element 13. At this time, d ₁ and d ₂ are the distance between the first and second voltage detectors 31 and 32 of two metal plates provided as voltage detectors and the length of the Pockels element 13. Comparing d ₁ and d ₂ gives d ₁ > d ₂ . Therefore, (1 + d ₁ / d ₂ ) always has a value greater than 1, so E _total has a value greater than E. In general, since d ₁ > 5 * d ₂ , if the first and second voltage detectors 31 and 32 are used, at least five times more electric fields can be applied to the Pockels element 13 than when not in use. Higher precision voltage measurement output can be obtained.

The coating electrode film 34 applies a voltage proportional to the measurement voltage of the voltage measurement target from the first and second voltage detectors 31 and 32 through the voltage transmission lead 33 to both ends of the Pockels element 13. . On the other hand, when the voltage transmission lead wire 33 is directly connected to the Pockels element 13 without the coating electrode film 34, the voltage is applied only to the corners of the Pockels element so that an inequality electric field is intensified. If the inequality is severe, the refractive index of the Pockels element, which is changed by the electric field according to the degree of inequality, also occurs within the element. Therefore, in order to make the state closer to the equal electric field, the electrode films 34 are coated on both end surfaces of the Pockels element. Since the coating electrode film 34 is installed, it is possible to make an electric field state closer to equality than when only the edge is applied. The coating electrode film 34 is formed with indium tin oxide (In ₂ O ₃ -SnO ₂ ) glass (so-called ITO glass) that can transmit light and has a conduction performance.

As described above in detail, the present invention improves the reliability of voltage measurement by applying a high electric field to the Pockels element using a voltage detector, and has an effect of simplifying the installation by reducing the space occupied by the sensor.

In addition, by coating an electrode film on both ends of the Pockels element, an equal electric field is applied to the element, thereby maintaining the refractive index of the Pockels element equal, thereby improving accuracy of voltage measurement.

Claims (3)

A first polarizer configured to polarize and output only light oscillating in the vertical direction from the laser incident light; 1/4 wavelength for generating circularly polarized light by separating light oscillating in the vertical direction from the first polarizer into vertical and horizontal coordinate components, and horizontally delaying the horizontal coordinate component by 90 degrees. Plate; According to the intensity of the applied electric field, Pockels outputs the elliptical polarization of the incident light from the quarter-wave plate by varying the optical refractive index of the incident light and the vertical refractive light component to generate a phase delay. An element; A first voltage detector installed opposite to a high voltage measurement object and configured to output a voltage proportional to the high voltage of the measurement object; A second voltage detector provided opposite to the ground potential of the measurement target of the high voltage and made of a metal plate for outputting a voltage proportional to the voltage of the ground potential; An electrode film coated on both ends of the Pockels element in a longitudinal direction and configured to apply voltages from the first and second voltage detectors to both ends of the Pockels element; And a lead wire made of an electrical conductor for transferring the voltages from the first and second voltage detectors to the electrode film. The detector-type photovoltage detector according to claim 1, wherein the photovoltage detector is installed in an electric field application direction between a conductor to which a high voltage of the voltage measuring target device is applied and a grounded enclosure of the target equipment. [Claim ₂ ] The photovoltaic detector of claim 1, wherein the coating electrode film is made of indium tin oxide (In ₂ O ₃ -SnO ₂ ) glass that transmits light and has a conducting performance.

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