CN112580207A - Coaxial double-hemisphere voltage dividing device of optical voltage transformer and optimization method thereof - Google Patents

Coaxial double-hemisphere voltage dividing device of optical voltage transformer and optimization method thereof Download PDF

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CN112580207A
CN112580207A CN202011510228.7A CN202011510228A CN112580207A CN 112580207 A CN112580207 A CN 112580207A CN 202011510228 A CN202011510228 A CN 202011510228A CN 112580207 A CN112580207 A CN 112580207A
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hemisphere
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黄奕钒
徐启峰
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
    • G01R15/247—Details of the circuitry or construction of devices covered by G01R15/241 - G01R15/246
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Abstract

The invention relates to a coaxial double-hemisphere voltage division device of an optical voltage transformer, which comprises a high-voltage lead, a high-voltage electrode, a ground electrode, an insulating sleeve, a light source, a multimode optical fiber, a polarizer, an electro-optic crystal, a quarter-wave plate, a radial polarization analyzer, an image transmission optical fiber bundle, an image processing system and epoxy resin, wherein the high-voltage lead is connected with the high-voltage electrode; the voltage to be measured is connected to the high-voltage electrode through the high-voltage lead; the ground electrode is sleeved outside the high-voltage electrode and is coaxial with the high-voltage electrode; the ground electrode and the high-voltage electrode are both arranged in the insulating sleeve; an optical signal emitted by the light source is transmitted by the multimode optical fiber and sequentially passes through the polarizer, the electro-optic crystal, the quarter-wave plate and the radial analyzer; electro-optic phase delay generated by the electro-optic crystal is converted into synchronous rotation of emergent light spots by a radial analyzer, and light spot signals are transmitted to an image processing system by an image transmission optical fiber bundle; the interior of the insulative sleeve is cured with an epoxy resin. The invention prevents the electro-optic crystal from being influenced by electric field aggregation and stray electric fields, and improves the accuracy and reliability of the mutual inductor.

Description

Coaxial double-hemisphere voltage dividing device of optical voltage transformer and optimization method thereof
Technical Field
The invention relates to the technical field of voltage measurement of power systems, in particular to a coaxial double-hemisphere voltage dividing device of an optical voltage transformer and an optimization method thereof.
Background
The optical voltage transformer overcomes the problems of ferromagnetic resonance, magnetic saturation and the like, has the advantages of small volume, light weight, safety, reliability and the like, and has good application prospect. The measurement principle of the existing optical voltage transformer is mainly based on the Pockels effect, namely, the electro-optic crystal is used for sensing an electric field to be measured so as to measure the voltage. The electro-optic crystal can be divided into lateral modulation and longitudinal modulation according to different measurement modes. In practical applications, the laterally modulated electro-optic crystal is highly susceptible to interference from external electric fields, including: electric field aggregation between electrodes causes electric field distribution distortion in the crystal, and stray electric fields introduced by interphase interference, insulator pollution, electrode shape and size and the like influence the electric field distribution in the crystal. The interference of an external electric field causes the sensitive additional phase delay of the electro-optical crystal, thereby introducing measurement errors and damaging the accuracy and reliability of the optical voltage transformer.
Disclosure of Invention
In view of the above, the present invention provides a coaxial dual-hemisphere voltage divider of an optical voltage transformer and an optimization method thereof, so that an electro-optical crystal disposed between electrodes is not affected by an electric field concentration and a stray electric field, and the accuracy and reliability of the transformer are improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a coaxial double-hemisphere voltage division device of an optical voltage transformer comprises a high-voltage lead, a high-voltage electrode, a ground electrode, an insulating sleeve, a light source, a multimode optical fiber, a polarizer, an electro-optic crystal, a quarter-wave plate, a radial analyzer, an image transmission optical fiber bundle, an image processing system and epoxy resin; the voltage to be measured is connected to the high-voltage electrode through the high-voltage lead; the ground electrode is sleeved outside the high-voltage electrode and is coaxial with the high-voltage electrode; the ground electrode and the high-voltage electrode are both arranged in the insulating sleeve; an optical signal emitted by the light source is transmitted by the multimode optical fiber and sequentially passes through the polarizer, the electro-optic crystal, the quarter-wave plate and the radial analyzer; electro-optic phase delay generated by the electro-optic crystal is converted into synchronous rotation of emergent light spots by a radial analyzer, and light spot signals are transmitted to an image processing system by an image transmission optical fiber bundle; the interior of the insulative sleeve is cured with an epoxy resin.
Furthermore, the shapes of the end parts of the high-voltage electrode and the ground electrode are both hemispheres, and the high-voltage electrode is arranged on the central axis of the ground electrode to form a coaxial double-hemisphere electrode structure.
An optimization method of a coaxial double-hemisphere voltage division device of an optical voltage transformer comprises the following steps:
step S1: constructing an electric field model of a coaxial double-hemisphere electrode structure;
step S2: presetting constraint conditions of electrode structure parameters;
step S3: calculating the electric field distribution of the coaxial double-hemisphere electrode structure under different constraint conditions, and establishing a mathematical model of measurement errors and electrode structure parameters introduced by an external electric field according to the calculation result;
step S4: and solving the mathematical model by adopting a group intelligent algorithm to obtain the structural parameters of the coaxial double-hemisphere electrodes when the measurement error is minimum, so as to obtain the optimal electric field distribution structure.
Further, the constraint conditions of the electrode structure parameters in step S2 are specifically:
Figure DEST_PATH_IMAGE002
(1)
wherein the content of the first and second substances,Dthe space between the electro-optical crystal and the high-voltage electrode;L 1is the side length of the electro-optic crystal;R 1is the radius of the high voltage electrode;R 2is the radius of the ground electrode;dis the thickness of the ground electrode;L 2is the length of the electrode.
Further, the mathematical model specifically includes:
Figure DEST_PATH_IMAGE004
(2)
wherein the content of the first and second substances,E A measurement errors introduced for external electric fields;f(. represents)E A AndD、L 1、R 1、R 2、dandL 2the functional relationship of (a).
Compared with the prior art, the invention has the following beneficial effects:
the invention prevents the electro-optic crystal arranged between the electrodes from being influenced by electric field aggregation and stray electric fields, and improves the accuracy and the reliability of the mutual inductor.
Drawings
FIG. 1 is a schematic view of the apparatus of the present invention;
FIG. 2 is a parametric illustration of a coaxial dual hemispherical electrode structure in accordance with an embodiment of the present invention;
FIG. 3 shows an electro-optic crystal according to an embodiment of the present inventionyzElectric field distribution of the cross section along each coordinate axis direction;
FIG. 4 is a flow chart of a method according to an embodiment of the present invention
In the figure: 1-high voltage wire, 2-high voltage electrode, 3-ground electrode, 4-insulating sleeve, 5-light source, 6-multimode fiber, 7-polarizer, 8-electro-optical crystal, 9-quarter wave plate, 10-radial analyzer, 11-image transmission fiber bundle, 12-image processing system, 13-epoxy resin, 14-side length of electro-optical crystal, 15-interval between electro-optical crystal and ground electrode, 16-radius of high voltage electrode, 17-radius of ground electrode, 18-thickness of ground electrode and 19-length of electrode.
Detailed Description
The invention is further explained below with reference to the drawings and the embodiments.
Referring to fig. 1, the present invention provides a coaxial dual-hemisphere voltage divider of an optical voltage transformer, which includes a high voltage conducting wire, a high voltage electrode, a ground electrode, an insulating sleeve, a light source, a multimode fiber, a polarizer, an electro-optic crystal, a quarter-wave plate, a radial analyzer, an image transmission fiber bundle, an image processing system and epoxy resin; the voltage to be measured is connected to the high-voltage electrode through the high-voltage lead; the ground electrode is sleeved outside the high-voltage electrode and is coaxial with the high-voltage electrode; the ground electrode and the high-voltage electrode are both arranged in the insulating sleeve; an optical signal emitted by the light source is transmitted by the multimode optical fiber and sequentially passes through the polarizer, the electro-optic crystal, the quarter-wave plate and the radial analyzer; electro-optic phase delay generated by the electro-optic crystal is converted into synchronous rotation of emergent light spots by a radial analyzer, and light spot signals are transmitted to an image processing system by an image transmission optical fiber bundle; the interior of the insulative sleeve is cured with an epoxy resin.
Preferably, in this embodiment, the electro-optic crystal is placed between the electrodes, and adopts a lateral modulation mode, and is partially pressure-divided with the epoxy resin to meet the measurement requirement of high voltage. Compared with SF6 gas, the difference between the dielectric constants of the epoxy resin and the electro-optic crystal is smaller, which is beneficial to improving the electric field distribution in the crystal. The coaxial double-hemisphere electrode can eliminate the influence of electric field concentration and stray electric fields on the electro-optic crystal;
referring to fig. 4, preferably, in this embodiment, the coaxial dual-hemispherical electrode structure is optimized by a method combining finite element and Matlab software, and the electric field distribution of the electro-optic crystal is further improved, specifically:
step S1: constructing an electric field model of a coaxial double-hemisphere electrode structure;
step S2: presetting constraint conditions of electrode structure parameters:
Figure DEST_PATH_IMAGE006
(1)
wherein the content of the first and second substances,Dthe space between the electro-optical crystal and the high-voltage electrode;L 1is the side length of the electro-optic crystal;R 1is the radius of the high voltage electrode;R 2is the radius of the ground electrode;dis the thickness of the ground electrode;L 2is the length of the electrode;
step S3: calculating the electric field distribution of the coaxial double-hemisphere electrode structure under different constraint conditions, and establishing a mathematical model of measurement errors and electrode structure parameters introduced by an external electric field according to the calculation result;
the mathematical model is specifically as follows:
Figure 461468DEST_PATH_IMAGE004
(2)
wherein the content of the first and second substances,E A measurement errors introduced for external electric fields;f(. represents)E A AndD、L 1、R 1、R 2、dandL 2the functional relationship of (a);
step S4: solving the mathematical model by using a group intelligent algorithm to obtain a solving formula (2), and obtaining the structural parameters of the coaxial double-hemisphere electrodes when the measurement error is minimum, so as to obtain the optimal electric field distribution structure.
Example 1:
in this embodiment, referring to FIG. 1, the light-passing direction of the transverse modulation electro-optic crystal is alongyAnd the electro-optical crystal is subjected to an electric field to be measured along the z-axis direction. The electro-optic crystal also senses the edges due to the influence of external electric fields, including field concentrations and stray electric fieldsxShaft andythe axial electric field, which creates additional phase delay, introduces measurement error. This measurement error can be quantitatively calculated by a finite element electric field model.
According to FIG. 2, let the voltage class of the optical voltage transformer be 110kV, and the side length of the electro-optical crystal beL 1=10mm, the distance between the electro-optical crystal and the high-voltage electrode isD=50mm, radius of the high-voltage electrode isR 1=25mm, radius of the ground electrode isR 2=125mm, thickness of ground electroded=25mm, length of electrodeL 2=200 mm. An electric field model of a coaxial double-hemisphere structure is constructed through finite elements, and an electro-optic crystal is calculatedyzPlanar (i.e. the direction of the electric field to be measured) alongxA shaft,yShaft andzthe electric field distribution of the axis is shown in fig. 3. Wherein the edgexA shaft,yElectric field distribution in the axial direction is close to 0 alongzThe electric field distribution of the shaft is relatively uniform. According to the Pockels effect, for electro-optical crystal edgesxA shaft,yShaft andzintegrating the field intensity in the axial direction to obtainU x 、U y 、U z . WhereinU x AndU y i.e. the measurement error introduced by the external electric field,U z the voltage to be measured is obtained. The results of the calculations are shown in Table 1, toU z Is a standard voltage, thenU x AndU y the effect of (c) was below 0.053% and 0.019%, respectively, and was negligible. Therefore, the coaxial double-hemisphere electrode can eliminate the influence of electric field concentration and stray electric fields on the transverse modulation electro-optic crystal and improve the distribution of an interelectrode electric field.
TABLE 1 measurement error introduced by external electric field
zShaft xShaft yShaft
Voltage ofU/V 386.52 0.205 0.074
Error/(%) / 0.053 0.019
Example 2:
in this embodiment, a 110kV voltage class is taken as an example for further description, and Matlab and ANSYS Maxwell are adopted for combined optimization. Firstly, calculating measurement errors introduced by an external electric field under different electrode structures, and constructing a mathematical model of the errors by adopting a particle swarm-support vector machine hybrid algorithm, wherein the mathematical model is shown as a formula (2). To be provided withE A As an optimization target, the formula (2) is used as a fitness function, and the fitness function is solved by a particle swarm intelligent algorithm again to obtain the fitness functionE A The minimum structural parameters of the coaxial double-hemisphere electrode are as follows:
Figure DEST_PATH_IMAGE010
(3)
in addition, the measurement error under the structure is obtained by optimizingE A =0.0014%。
Substituting the structural parameters of formula (3) into the finite element electric field model, and calculating the edgexShaft andythe measurement error in the axial direction is shown in table 2. In comparison with table 1, the influence of the external electric field is further reduced. In addition, calculatexShaft andysum of axial errorsE A '= 0.0016%. Simulation results (E A ') And particle group optimization results (E A ) And consistently, the effectiveness of the embodiment is verified.
TABLE 2 optimization of measurement errors introduced by external electric field in rear electrode structure
zShaft xShaft yShaft
Voltage ofU/V 734.97 0.0031 0.0095
Error/(%) / 0.0004 0.0012
The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims (5)

1. A coaxial double-hemisphere voltage division device of an optical voltage transformer is characterized by comprising a high-voltage lead, a high-voltage electrode, a ground electrode, an insulating sleeve, a light source, a multimode fiber, a polarizer, an electro-optic crystal, a quarter-wave plate, a radial analyzer, an image transmission fiber bundle, an image processing system and epoxy resin; the voltage to be measured is connected to the high-voltage electrode through the high-voltage lead; the ground electrode is sleeved outside the high-voltage electrode and is coaxial with the high-voltage electrode; the ground electrode and the high-voltage electrode are both arranged in the insulating sleeve; an optical signal emitted by the light source is transmitted by the multimode optical fiber and sequentially passes through the polarizer, the electro-optic crystal, the quarter-wave plate and the radial analyzer; electro-optic phase delay generated by the electro-optic crystal is converted into synchronous rotation of emergent light spots by a radial analyzer, and light spot signals are transmitted to an image processing system by an image transmission optical fiber bundle; the interior of the insulative sleeve is cured with an epoxy resin.
2. The coaxial double-hemisphere voltage dividing device of the optical voltage transformer as claimed in claim 1, wherein the end portions of the high voltage electrode and the ground electrode are both shaped as hemispheres, and the high voltage electrode is mounted on a central axis of the ground electrode to form a coaxial double-hemisphere electrode structure.
3. An optimization method of a coaxial double-hemisphere voltage division device of an optical voltage transformer is characterized by comprising the following steps:
step S1: constructing an electric field model of a coaxial double-hemisphere electrode structure;
step S2: presetting constraint conditions of electrode structure parameters;
step S3: calculating the electric field distribution of the coaxial double-hemisphere electrode structure under different constraint conditions, and establishing a mathematical model of measurement errors and electrode structure parameters introduced by an external electric field according to the calculation result;
step S4: and solving the mathematical model by adopting a group intelligent algorithm to obtain the structural parameters of the coaxial double-hemisphere electrodes when the measurement error is minimum, so as to obtain the optimal electric field distribution structure.
4. The method according to claim 3, wherein the constraints of the electrode structure parameters of step S2 are specifically:
Figure 308265DEST_PATH_IMAGE001
(1)
wherein the content of the first and second substances,Dthe space between the electro-optical crystal and the high-voltage electrode;L 1is the side length of the electro-optic crystal;R 1is the radius of the high voltage electrode;R 2is the radius of the ground electrode;dis the thickness of the ground electrode;L 2is the length of the electrode.
5. The method according to claim 3, wherein the mathematical model is specifically:
Figure 884740DEST_PATH_IMAGE002
(2)
wherein the content of the first and second substances,E A measurement errors introduced for external electric fields;f(. represents)E A AndD、L 1、R 1、R 2、dandL 2the functional relationship of (a).
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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN115166332A (en) * 2022-07-28 2022-10-11 福州大学 Method and system for regulating and controlling half-wave voltage of electro-optic crystal based on centrosymmetric electrode
CN115166332B (en) * 2022-07-28 2024-05-31 福州大学 Method and system for regulating half-wave voltage of electro-optic crystal based on central symmetrical electrode

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Publication number Priority date Publication date Assignee Title
CN115166332A (en) * 2022-07-28 2022-10-11 福州大学 Method and system for regulating and controlling half-wave voltage of electro-optic crystal based on centrosymmetric electrode
CN115166332B (en) * 2022-07-28 2024-05-31 福州大学 Method and system for regulating half-wave voltage of electro-optic crystal based on central symmetrical electrode

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