JP2010068665A - Optical voltage measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photovoltage measuring device which divides voltage without receiving the influence of environmental characteristics, such as, temperature and humidity, and measures a main circuit voltage at high accuracy. <P>SOLUTION: The photovoltage measuring device includes a main circuit conductor 1; a dielectric 2 which supports the main circuit conductor 1 in an insulated state and is fixed to a ground member 3; an embedded electrode 6 buried in the dielectric 2; and an electro-optic element 20 for measuring a voltage of the main circuit conductor 1 connected to the embedded electrode 6. A voltage resulting from voltage division at the capacitance ratio between a capacitance between the main circuit conductor 1 and the embedded electrode 6 and the capacitance between the buried electrode 6, and the ground member 3 is applied to the electro-optic element 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical voltage measurement device capable of improving the measurement accuracy of a main circuit voltage of a switchgear used in a power generation substation or the like.

  In a high-voltage switchgear of several kV or more, the main circuit voltage is measured by capacitance division or resistance division. As this type of measuring apparatus, a cone-shaped insulating spacer used in a gas-insulated switchgear as shown in FIG. 3 is known (for example, see Patent Document 1).

  As shown in FIG. 3, the main circuit conductor 1 is supported by a cone-shaped insulating spacer 2 and insulated from a tank 3 having a cylindrical ground potential. The insulating spacer 2 includes a first dielectric 4 formed by casting an epoxy resin, and a second dielectric 5 having a lower resistivity than that and provided in a layered manner on the surface. An annular embedded electrode 6 is embedded in the first dielectric 4 on the tank 3 side. An annular embedded metal 7 is provided at both ends of the outer peripheral end portion and is airtightly fixed to the end of the tank 3.

  A secondary side capacitor 8 is connected to the embedded electrode 6 and is grounded through the embedded metal 7. A detection impedance 9 is connected to the secondary capacitor 8 in parallel. A primary-side capacitance 10 and a primary-side volume resistance 11 due to the second dielectric 5 are formed between the main circuit conductor 1 and the embedded electrode 6.

  Thereby, the voltage divided by the primary side capacitance 10 and the secondary side capacitor 8 including the detection impedance 9 can be measured. The second dielectric 5 is provided for improving the time constant. When the frequency is high, the voltage is divided by the primary side volume resistance 11, and the main circuit voltage can be accurately measured.

On the other hand, a voltage measurement using an electro-optic element (Pockels effect element) is known (see, for example, Patent Document 2). However, the voltage that can be applied to the electro-optic element is about 1 kV or less, and a voltage divider must be used to measure a high voltage. For this reason, a high-precision voltage divider is required. However, when the dielectric strength is taken into consideration, the voltage divider becomes large and the gas insulated switchgear itself becomes large.
Japanese Unexamined Patent Publication No. 2000-232719 (4th page, FIG. 1) JP 2000-258465 A (third page, FIG. 1)

  The main circuit voltage measurement of the above-described conventional high voltage switchgear has the following problems. If an electro-optic element is to be used, a dedicated voltage divider is required, and the gas insulated switchgear becomes large. Therefore, when a voltage dividing circuit is made using the insulating spacer 2 and the main circuit voltage is measured, the primary side capacitance 10 and the primary side volume resistance 11 of the primary side voltage dividing circuit are in the tank 3, and The secondary side capacitor 8 and the detection impedance 9 of the secondary voltage dividing circuit are in the air outside the tank 3. In the tank 3, there is a temperature rise due to the energization current, and there is a change in temperature outside the tank 3, and it is difficult to make the temperature characteristics of the voltage dividing circuits on the primary side and the secondary side the same. Further, although the humidity is low in the tank 3, it is affected by the humidity outside the tank 3.

  For this reason, a voltage dividing circuit that can have the same environmental characteristics such as temperature and humidity by using the insulating spacer 2 that is an insulating structure of the gas insulated switchgear is used to measure the main circuit voltage with high accuracy. Was desired. Further, when an electro-optic element is used, it has been desired to connect the electro-optic element so that the impedance on the secondary side does not change greatly and a stable voltage dividing ratio can be obtained.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical voltage measuring device that measures a main circuit voltage with high accuracy without being affected by environmental characteristics.

  In order to achieve the above object, an optical voltage measuring device according to the present invention comprises a main circuit conductor, a dielectric that supports the main circuit conductor insulatively, is fixed to a ground member, and is embedded in the dielectric. An electro-optic element for measuring a voltage of the main circuit conductor connected to the embedded electrode, and the electro-optic element includes the main circuit conductor and the embedded electrode, and the embedded electrode; A voltage divided by a capacitance ratio formed between the ground members is applied.

  According to the present invention, the primary side capacitance and the secondary side capacitance are formed of the same insulating material, and the voltage divided by these capacitance ratios is connected to the electro-optic element. The capacitance ratio is not affected by environmental characteristics such as temperature and humidity, and the main circuit voltage can be measured with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an optical voltage measuring apparatus according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an insulating spacer that functions as a voltage divider according to Embodiment 1 of the present invention. In FIG. 1, the same components as those in the prior art are denoted by the same reference numerals.

  As shown in FIG. 1, a main circuit conductor 1 of a gas insulated switchgear is supported and fixed to a cone-shaped insulating spacer 2 and insulated from a cylindrical tank (grounding member) 3 having a ground potential. The insulating spacer 2 is composed of a first dielectric 4 formed by casting an epoxy resin. An annular embedded electrode 6 is embedded in the first dielectric 4 on the tank 3 side. An annular embedded metal 7 is provided at both ends of the outer peripheral end portion and is airtightly fixed to the end of the tank 3. The tank 3 is filled with an insulating gas.

  One end of an electro-optic element 20 using a single crystal such as BGO or BSO is connected to the embedded electrode 6, and the other end of the electro-optic element 20 is grounded. The electro-optic element 20 includes a light source driving device 21, a light source 22 such as a light emitting diode, an optical fiber 23, a light transmission collimator unit 24, a polarizer 25 that converts incident light into linearly polarized light, and 1 / that converts linearly polarized light into circularly polarized light. Measurement light (optical signal) for measuring voltage is incident through the four-wavelength plate 26.

  In the electro-optic element 20, the incident circularly polarized light is converted into elliptical light according to the magnitude of the electric field intensity and emitted. The measurement light passes through the analyzer 27 and only one polarization component is emitted. Then, it is guided to the optical fiber 29 by the light receiving collimator unit 28 and sent to the detector 30. In the detector 30, the measurement light is converted into an electric signal, and the measured voltage is calculated by the electronic circuit 31. The light transmitting collimator unit 24 to the light receiving collimator unit 28 are housed in a shield case 32 that removes the influence of the electric field.

  In the insulating spacer 2, a primary side capacitance 10 is formed between the main circuit conductor 1 and the embedded electrode 6, and a secondary side capacitance 33 is formed between the embedded electrode 6 and the tank 3. For this reason, the voltage divided by the primary side capacitance 10 and the combined capacitance of the capacitance of the electro-optic element 20 itself and the secondary side capacitance 33 is applied to the electro-optic element 20. .

  Here, the capacitance of the electro-optic element 20 is much smaller than the secondary side capacitance 33, and the voltage division ratio is substantially determined by the secondary side capacitance 33. This is because the electrode arrangement between the embedded electrode 6 and the tank 3 is a coaxial electrode arrangement even though the relative permittivity of the electro-optic element 20 is larger than that of the epoxy resin, and the opposing electrode area is larger than that of the electro-optic element 20. This is because the size will be much larger. With the insulating spacer 2 having a diameter of about 300 mm, the capacitance ratio between the electro-optic element 20 and the secondary-side capacitance 33 is 100 times or more.

  As a result, a voltage divided by the capacitance ratio between the primary side capacitance 10 and the secondary side capacitance 33 is applied to the electro-optic element 20, and the main circuit voltage can be measured. The primary side capacitance 10 and the secondary side capacitance 33 are formed of the same epoxy resin, and the change in the capacitance with the temperature change is the same. Further, since the inside of the tank 3 is kept constant at a predetermined low humidity, it is not affected by the humidity. That is, the primary side capacitance 10 and the secondary side capacitance 33 are exposed to the same environment. Although the floating capacitance in the insulating gas is added to the primary-side capacitance 10, it is not affected by environmental characteristics as described above.

  According to the optical voltage measuring apparatus of the first embodiment, the embedded electrode 6 is embedded in the first dielectric 4 made of epoxy resin, and the voltage applied to the electro-optic element 20 is formed of the same epoxy resin. Since the primary side capacitance 10 and the secondary side capacitance 33 are divided, the capacitance ratio is not affected by environmental characteristics such as temperature and humidity, and the main circuit voltage is measured with high accuracy. Can do.

  Next, an optical voltage measuring apparatus according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of a post spacer that functions as a voltage divider according to the second embodiment of the present invention. The difference between the second embodiment and the first embodiment is an insulator that functions as a voltage divider. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the main circuit conductor 1 connected by the coupling 35 is supported and fixed by a post spacer 36 formed of a first dielectric 4 made of epoxy resin. In the first dielectric 4, a main circuit side embedded metal 37 is embedded on the coupling 35 side, and a cylindrical ground side embedded metal 38 is embedded on the tank 3 side and fixed to the tank 3. Further, a cylindrical embedded electrode 39 for dividing the main circuit voltage is embedded in the substantially central portion of the ground-side embedded metal 38. An electro-optic element is connected to the embedded electrode 39.

  As a result, a primary side capacitance 40 is formed between the main circuit side embedded metal 37 and the embedded electrode 39, and a secondary side capacitance 41 is formed between the embedded electrode 39 and the ground side embedded metal 38. The voltage is divided. A coaxial electrode is disposed between the buried electrode 39 and the ground side buried metal 38, and the secondary side capacitance 41 is larger than the primary side capacitance 40. These capacitances 40 and 41 are formed of the first dielectric 4 that is the same insulating material and are used in the same environment, and therefore are not affected by the environmental characteristics.

  According to the optical voltage measurement apparatus of the second embodiment, the same effect as that of the first embodiment can be obtained.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above embodiment, the first dielectric 4 is described using a general epoxy resin. However, if an inorganic material such as silica is filled, temperature characteristics can be relaxed. In addition, the relative permittivity can be easily adjusted by the mixing ratio, and the capacitance selection range can be increased. Furthermore, other insulating materials applied to electric devices such as polycarbonate resin, polyester resin, and phenol resin can be used.

  Moreover, when it is used in the controlled electric room etc. and the creeping leakage current due to fouling wetness can be ignored, it can be applied even in the air. That is, when the primary side capacitances 10 and 40 and the secondary side capacitances 33 and 41 are formed of the same insulating material, used in the same environment, and have excellent creeping dielectric strength, the main circuit The voltage can be measured with high accuracy.

Sectional drawing of the insulating spacer which functions as a voltage divider concerning Example 1 of the present invention. Sectional drawing of the post spacer which functions as a voltage divider concerning Example 2 of the present invention. Sectional drawing of the insulation spacer which functions as a conventional voltage divider.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main circuit conductor 2 Insulating spacer 3 Tank 4 1st dielectric material 5 2nd dielectric material 6 and 39 Embedded electrode 7, 37, 38 Embedded metal 8 Secondary side capacitor 9 Detection impedance 10, 40 Primary side capacitance 11 Primary-side volume resistance 20 Electro-optical element 21 Light source driving device 22 Light source 23, 29 Optical fiber 24 Transmitting collimator unit 25 Polarizer 26 1/4 wavelength plate 27 Analyzer 28 Light receiving collimator unit 30 Detector 31 Electronic circuit 32 Shield case 33, 41 Secondary capacitance 35 Coupling 36 Post spacer

Claims (4)

A main circuit conductor;
Insulating and supporting the main circuit conductor, and a dielectric fixed to the ground member;
Embedded electrodes embedded in the dielectric,
An electro-optic element for measuring a voltage of the main circuit conductor connected to the embedded electrode,
The electro-optic element is applied with a voltage divided by a capacitance ratio formed between the main circuit conductor and the embedded electrode and between the embedded electrode and the ground member. Voltage measuring device.   The photovoltage measuring device according to claim 1, wherein capacitances formed between the main circuit conductor and the embedded electrode and between the embedded electrode and the ground member are exposed to the same environment. .   The photovoltage measuring device according to claim 1, wherein the embedded electrode and the ground member are arranged in a coaxial electrode.   The photovoltage measuring device according to any one of claims 1 to 3, wherein the dielectric is an epoxy resin.

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