JPS63256865A - Optical detector for phase voltage - Google Patents

Abstract

PURPOSE:To decrease the number of components by using three optical voltage sensors, splitting light from one light source into two by a polarization beam splitter and supplying them to sensors, and multiplexing modulated light signals optically by beam splitters of adjacent sensors and obtaining a differential light signal. CONSTITUTION:The light from the light source 6 is made incident on an optical voltage sensor S1 through an optical fiber 1 and split into P and S polarized light beams by the polarization beam splitter 10, and one light beam is made into a light signal modulated according to a voltage by a Pockels effect element 4 and a polarization beam splitter 11. This light signal is sent to the polarization beam splitter 11 and a 2nd adjacent sensor S2 and Pockels effect element by an optical fiber 1' and multiplexed, and the other polarized light beam is incident on a 3rd sensor S3 without being modulated and multiplexed by the polarization beam splitter 11; and voltages Eu, Ev, and Ew generated at the respective sensors S1-S3 are processed to obtain phase voltages.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phase-to-phase voltage detection device for power transmission and distribution lines using an optical voltage sensor.

[Prior Art] Voltage can be measured using an electro-optical element using an optical voltage sensor as shown in FIG.

A polarizer 2.1/
A four-wavelength plate 3, a Pockels effect element 4, and an analyzer 5 are arranged. When a voltage is applied to the Pockels effect element 5, the output light from the light source becomes linearly polarized light by the polarizer 2, and becomes circularly polarized light by the next 1/4 wavelength plate.

When this circularly polarized light passes through the Pockels effect element 4, it becomes elliptically polarized light due to the applied electric field, and the ellipticity is proportional to the applied electric field strength. The analyzer 5 passes only polarized light in a specific direction,
When elliptically polarized light passes through it, a light output with an intensity proportional to the ellipticity, that is, to the applied electric field, is obtained.

An example of the Pockels effect element is BSO (bismuth oxide crystal).

A configuration for detecting phase-to-phase voltage of a three-phase power transmission/distribution line using such a photovoltage sensor has, for example, a configuration as shown in FIG. 2.

In the figure, Eu, Ev, and Ew indicate the ground voltage of each phase of the three-phase transmission wiring conductor, and S++82. S3 is a voltage set corresponding to the U, V, and W phases using a Pockels effect element as shown in FIG. 3 above. If the voltage is high, a voltage transformer (not shown) is used to step down the voltage, and the sensor 311 S2.
S3 is connected to, for example, one Eta terminal of a Pockels effect element, and the other terminal is grounded.

6 is a light source such as an LED (light emitting diode), and each light source 6 is connected to an optical fiber 7, and the rear end of the optical fiber 7 enters the polarizer 2 of the photoelectric sensor sl, S2+S3 ( Figure 3). The light leaving the analyzer 5 is guided by an optical fiber 1' to a light receiver 8, for example a PD (photodiode), shown in FIG. 2. Receiver 8
The output changed into an electrical quantity is subtracted by three differential amplifiers 9 to generate an interphase voltage proportional to N Vuv + Vvw + Vwu.

[Problems to be Solved by the Invention] With the above configuration, phase-to-phase voltage can be measured, but three differential amplifiers and three light sources are required.
There are many parts in the device configuration, and differential amplifiers in particular must have sufficiently uniform characteristics, which generally leads to a problem of low reliability.

[Structure of the Invention The present invention was made for the purpose of solving the above problems,
In short, three photoelectric voltage sensors are used, the light from one light source is divided into two stages by a polarizing beam splitter and applied to each photoelectric voltage sensor, and the optical signal modulated by each photoelectric voltage sensor is transmitted. The beam splitters of the adjacent photoelectric voltage sensors combine the lights, extract them as differential optical signals, and detect the phase-to-phase voltage from the ground-to-ground voltage.

The present invention will be explained below with reference to Examples. The same parts as in FIGS. 2 and 3 are indicated by the same reference numerals. A first photoelectric voltage sensor S1 is arranged with respect to the light sources, and the light emitted from the light sources enters the sensor S+ through the optical fiber 1. In the photoelectric voltage sensor S+, a polarizing beam splitter 10 is used as a polarizer on the light incident side. This polarizing beam splitter I
O, the light is divided into two polarized lights (P and S polarized lights). One becomes an optical signal modulated by the Pockels effect element 4 and the polarizing beam splitter 11 according to the voltage.

This optical signal is split by the polarizing beam splitter IO of the voltage sensor S+ at the analyzer (in this case, the polarizing beam splitter 11) of the second adjacent photoelectric voltage sensor S2 via the optical fiber 1', without being modulated. , the light incident on the second voltage sensor S2 is combined with the optical signal modulated by the Pockels effect element 4 and the polarizing beam splitter 11, and the Ev detected by the voltage sensor S2 and the Eu detected by 81 are Ev -Eu=Vuy is calculated using light.

Note that the Pockels effect element 4 of each photoelectric voltage sensor Sll S21 S3 is provided with Eu
+EV and EW are applied as they are or as a partial pressure.

In addition, the polarizing beam splitter 1 of the second voltage sensor S2
The other polarized light divided by 0 is not modulated,
The optical signal enters the third voltage sensor S3 and is modulated, and is combined with the optical signal modulated by the second voltage sensor S2 at the polarizing beam splitter (2). It will be done.

Further, the optical signal modulated by the third voltage sensor S3 is optically combined with the optical signal modulated by the first voltage sensor S1 by the polarization beam splitter 11 of the first voltage sensor S+, and Eu-Ew= The calculation resulting in Ewu is performed with light.

As described above, the present invention adopts a method in which the polarizing beam splitter of the voltage sensor is used not only as a polarizing analyzer but also for branching and combining, subtracting with light, and measuring the ground voltage.

Note that in order to perform subtraction with light, for example, in the case of subtraction between the output optical signal of Sl and the 82 output optical signal, if the output optical signal of Sl is an optical signal modulated on P-polarized light, then the S-polarized light is %S2. If you combine it with the modulated optical signal, it becomes the S2 polarizing beam splitter! The combined output optical signal from 1 is obtained by combining an output optical signal proportional to the intensity of the P-polarized light of SI and an output optical signal proportional to the intensity of S-polarized light of 82.

In this way, a phase-to-phase voltage is obtained in each of the three photoreceivers 8 in proportion to the phase-to-phase voltage, and if this output is amplified, (D
(Excluding C output) The phase-to-phase voltage VuV + VVWIVwu is the total
I can do it.

Needless to say, when the three-phase voltages are balanced, each optical sensor Sll S2 is
1. Needless to say, it is necessary to adjust the optical system of S3.

[Effects of the Invention] According to the present invention, without using a conventional differential amplifier,
Only one light source is required, the number of parts is reduced, and phase-to-phase voltage can be detected with high reliability.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the invention. FIG. 2 shows a conventional phase-to-phase voltage detection device. FIG. 3 is an explanatory diagram of the optical voltage sensor. 1.1'... Optical fiber, 4... Pockels effect element, 6... Light source, 8... Light receiver, 10.11...
Polarizing Beam Splitter 0 ・〉、〉 ・〉〉〉3 Proceedings Amendment (Method) July 1988/Ji Date 1, Incident Indication Relationship with Patent Application No. 91693 of 1988 Patent Applicant Residence Address: 5-15 Kitahama, Higashi-ku, Osaka City
Name (2+3) Sumitomo Electric Industries, Ltd. Representative: Tetsube Yogami 4, Agent address: 1-9-20 Nishinakajima, Yodoyo-ku, Osaka City
No. 5, Date of amendment order June 30, 1985 (shipment date) 6. In the specification subject to amendment Title of the invention and scope of claims column 7, Contents of amendment 1, Specification page 1, No. 3 In the title of the invention in line 1, "phase-to-phase voltage detection length jη" is corrected to "optical phase-to-phase voltage detection device." 2. The claims in Specification 8 are amended as shown in the attached sheet. Claims (1) Three optical voltage sensors are arranged to correspond to three-phase voltages, and the light from the light source is divided into two by the polarizing beam splitter of the first optical voltage sensor among the three sensors. Divided into polarized light,
Furthermore, one of the two polarized lights is divided into two polarized lights by the polarization beam splitter of the second Type 9 voltage sensor, one of which is input to a third optical voltage sensor, and modulated by the first optical voltage sensor. The received optical signal and the optical signal modulated by the second optical voltage sensor are optically synthesized by the beam splitter of the second optical voltage sensor, and the optical signal is modulated by the second optical voltage sensor. The optical signal and the optical signal modulated by the third optical voltage sensor are optically combined by the beam splitter of the third optical voltage sensor, and the optical signal modulated by the third optical voltage sensor and the optical signal modulated by the first optical voltage sensor are combined. Optical phase-to-phase voltage detection characterized in that an optical signal modulated by a photovoltage sensor is optically combined by a beam splitter of a first photovoltage sensor, and each combined optical output is output as an electrical signal via a light receiver. Device.

Claims (1)

[Claims] (1) Three optical voltage sensors correspond to three-phase voltages, and the light from the light source is divided into two polarized lights by the polarizing beam splitter of the first optical voltage sensor among the three sensors. ,
Further, one of the two polarized lights is split into two polarized lights by a polarization beam splitter of a second optical voltage sensor, one of which is input to a third optical voltage sensor, and modulated by the first optical voltage sensor. The received optical signal and the optical signal modulated by the second optical voltage sensor are optically combined by the beam splitter of the second optical voltage sensor, and the optical signal modulated by the second optical voltage sensor is generated. The optical signal modulated by the third optical voltage sensor is optically synthesized by the beam splitter of the third optical voltage sensor, and the optical signal modulated by the third optical voltage sensor and the first optical voltage are combined. A phase-to-phase voltage detection device characterized in that an optical signal modulated by a sensor is optically combined by a beam splitter of a first optical voltage sensor, and each combined optical output is outputted as an electrical signal via a light receiver.