electric field strength mesurement apparatus using FBG(fiber Bragg grating) and piezoelectric element

Abstract

The present invention relates to an electric field strength measuring device using a piezoelectric element and an optical fiber grating, comprising: a piezoelectric element that expands and contracts along the direction of an applied electric field; first and second fixing parts that are fixed and spaced apart from each other along the longitudinal direction of the piezoelectric element; a sensing optical fiber that is extended and fixed to the first and second fixing parts such that the grating is formed spaced apart from each other along the longitudinal direction of the optical fiber, and the optical fiber grating part formed with the grating is deformed in response to the expansion and contraction of the piezoelectric element; a light source unit that emits light; an optical circulator that outputs light emitted from the light source unit and input through an input terminal to an output terminal connected to the sensing optical fiber, and outputs reaction light incident in reverse from the sensing optical fiber to a detection terminal; a light detection unit that detects light output from the detection terminal of the optical circulator; and a calculation unit that controls the operation of the light source unit and measures the electric field strength of the area where the optical fiber grating part is installed from a signal received from the light detection unit. According to this electric field strength measuring device utilizing a piezoelectric element and an optical fiber grating, the use of the optical fiber grating and the piezoelectric element provides the advantage of being able to precisely measure electric field strength without being affected by electromagnetic interference.

Description

Technology Field

[0001] The present invention relates to an electric field strength measuring device using a piezoelectric element and an optical fiber grating, and more specifically, to an electric field strength measuring device using a piezoelectric element and an optical fiber grating capable of measuring the electric field strength through a sensing optical fiber having an optical fiber grating formed thereon. This project (result) is the result of research conducted under the Phase 3 Leading University for Industry-Academic Cooperation (LINC 3.0) program, which was funded by the Ministry of Education and the National Research Foundation of Korea. Background Technology

[0002] Casualties caused by lightning strikes during outdoor activities in thunderstorms are increasing every year. The annual average number of deaths from lightning accidents reaches approximately 24,000 worldwide, about 20 in Korea, and about 4,000 in China. In November 2018, the Korea Occupational Safety and Health Agency published technical guidelines on the installation of thunderstorm warning systems to classify the probability of lightning occurrence into several stages based on the magnitude of the electromagnetic field detected by warning devices used to forecast the risk of lightning.

[0003] Current lightning warning devices rely on detecting electromagnetic waves generated during a lightning strike, so there is a need for a lightning warning device that alerts users to a lightning strike before it occurs, allowing for advance evacuation.

[0004] Meanwhile, the power generated by power generation facilities reaches hundreds of megawatts and is transmitted in several stages; to reduce losses in transmission lines, it is transmitted at high voltages of 110 kV or higher, and the current magnitude exceeds several kA. Furthermore, very strong electromagnetic interference (EMI) occurs near power lines carrying high voltage and high current.

[0005] Meanwhile, a device for measuring electric field strength is disclosed in Korean published patent No. 10-2001-0063010. However, the method using electrical signals has the disadvantage that it can be affected by electromagnetic interference because the sensed signal is electrically output. The problem to be solved

[0006] The present invention was devised to improve upon the aforementioned problems, and aims to provide an electric field strength measuring device using a piezoelectric element and an optical fiber grating that can easily measure the electric field strength through the optical fiber grating. means of solving the problem

[0007] To achieve the above objective, an electric field strength measuring device using a piezoelectric element and an optical fiber grating according to the present invention comprises: a piezoelectric element that extends along the direction of an applied electric field; first and second fixing parts that are fixed and spaced apart from each other along the longitudinal direction of the piezoelectric element; a sensing optical fiber that is extended and fixed to the first and second fixing parts such that the grating is formed spaced apart from each other along the longitudinal direction of the optical fiber, and the optical fiber grating part in which the grating is formed is deformed in response to the extension of the piezoelectric element; a light source part that emits light; an optical circulator that outputs light emitted from the light source part and input through an input end to an output end connected to the sensing optical fiber, and outputs reaction light incident in reverse from the sensing optical fiber to a detection end; a light detection part that detects light output from the detection end of the optical circulator; and a calculation part that controls the operation of the light source part and measures the electric field strength of the area where the optical fiber grating part is installed from a signal received from the light detection part.

[0008] According to one aspect of the present invention, the sensing optical fiber is formed to have an etched portion along the longitudinal direction such that the optical fiber grating portion in which the grating is formed leaves only a part of the cladding, and the sensing optical fiber can be constructed such that the etched portion maintains a separated state with respect to the piezoelectric element.

[0009] In addition, the first and second extension portions, which extend outward from the etched portion and are coupled to the first and second fixed portions, can be constructed such that the stretching deformation of the piezoelectric element caused by the applied electric field is concentrated at the etched portion to increase measurement sensitivity.

[0010] Alternatively, the first and second extension portions, which extend to both sides beyond the etched portion and are coupled to the first and second fixing portions, may be constructed to be coupled to the first and second fixing portions in a tensioned state while separated from the piezoelectric element. Effects of the invention

[0011] According to the electric field strength measuring device using a piezoelectric element and an optical fiber grating according to the present invention, by using an optical fiber grating and a piezoelectric element, it provides the advantage of being able to precisely measure the electric field strength without being affected by electromagnetic interference. Brief explanation of the drawing

[0012] FIG. 1 is a drawing showing an electric field strength measuring device using a piezoelectric element and an optical fiber grating according to the present invention, and FIG. 2 is an enlarged view of the optical fiber grating coupling structure of FIG. 1, and Figure 3 is a graph showing an example of light received through a photodetector in response to the first grating of Figure 1. Specific details for implementing the invention

[0013] Hereinafter, an electric field strength measuring device using a piezoelectric element and an optical fiber grating according to a preferred embodiment of the present invention will be described in more detail with reference to the attached drawings.

[0014] FIG. 1 is a drawing showing an electric field strength measuring device using a piezoelectric element and an optical fiber grating according to the present invention, and FIG. 2 is an enlarged drawing showing the optical fiber grating coupling structure of FIG. 1.

[0015] Referring to FIGS. 1 and 2, an electric field strength measuring device using a piezoelectric element and an optical fiber grating according to the present invention comprises a light source (110), an optical circulator (120), a sensing optical fiber (140), a piezoelectric element (150), first and second fixing parts (161)(162), a light detection part (170), and a calculation part (180).

[0016] The light source (110) is applied as a light source unit and is controlled by the output unit (180) to emit light.

[0017] The optical circulator (120) outputs light emitted from the light source (110) and input through the input terminal (120a) to the output terminal (120b) connected to the sensing optical fiber (140), and outputs reaction light incident in reverse from the sensing optical fiber (140) to the detection terminal (120c).

[0018] The sensing optical fiber (140) has gratings (142) formed at equal intervals along the longitudinal direction of the optical fiber, and the optical fiber grating portion (143) in which the gratings (142) are formed is fixedly coupled through the first and second fixing portions (161) (162) described later along the longitudinal direction of the piezoelectric element (150) so as to deform in response to the stretching of the piezoelectric element (150).

[0019] One end of the sensing optical fiber (140) is connected to the output end of the optical circulator (120).

[0020] The piezoelectric element (150) is applied in a rod shape that is stretched along the direction of the applied electric field and has an appropriate length along the longitudinal direction. The piezoelectric element (150) may be applied in a cross-sectional shape orthogonal to the longitudinal direction, such as a square shape or a circular shape, and may have various shapes.

[0021] The piezoelectric element (150) can be installed to extend along a direction parallel to the direction of the electric field to be measured.

[0022] Meanwhile, an example of a coupling structure is described with reference to FIG. 2 to increase measurement sensitivity by concentrating the stretching deformation of the piezoelectric element (150) corresponding to the strength of the applied electric field of the piezoelectric element (150) on the optical fiber grating portion (143).

[0023] Referring to FIG. 2, the sensing optical fiber (140) is extended to have a core (140a) and a clad (140b) surrounding the core (140a), and the optical fiber grating portion (143) in which gratings (142) are formed is formed to have an etched portion (144) that is etched along the longitudinal direction so as to leave only a part of the clad (140b).

[0024] Additionally, the sensing optical fiber (140) is configured so that the etched portion (144) remains separated from the piezoelectric element (150). The first and second extended portions (141a) and (141b), which extend outward from the etched portion (144) of the sensing optical fiber (140) and are coupled to the first and second fixed portions (161) and (162), are bonded to the piezoelectric element (150) with a bonding material (136) so that the stretching deformation caused by the applied armature of the piezoelectric element (150) is concentrated on the etched portion (144), thereby increasing the measurement sensitivity.

[0025] That is, the stretching force generated along the entire length of the piezoelectric element (150) by the strength of the applied electric field is concentrated in the etched portion (144), which is separated from the bonding material (136) and has a smaller outer diameter than the portion of the sensing optical fiber (140) bonded by the bonding material (136), so that the rate of change in the spacing between the gratings (142) can be increased even with a minute change in the electric field.

[0026] Here, the bonding material (136) can be epoxy.

[0027] In contrast, the first and second extension portions (141a) (141b), which extend outward from the etching portion (144) and are coupled to the first and second fixing portions (161) (162), can, of course, be constructed to be coupled to the first and second fixing portions (161) (162) in a tensioned state while separated from the piezoelectric element (150).

[0028] The first and second fixing parts (161) (162) are each fixed to the piezoelectric element (150) at a distance from each other along the longitudinal direction of the piezoelectric element (150).

[0029] The first and second fixing parts (161)(162) are parts that fix the sensing optical fiber (140) to the piezoelectric element (150). The first and second fixing parts (161)(162) each have a through hole through which the sensing optical fiber (140) passes, and can be constructed in a structure that fixes the sensing optical fiber (140) with an adhesive that closes the through hole so that the sensing optical fiber (140) inserted through the through hole is fixed to the through hole.

[0030] The light detection unit (170) detects light output from the detection unit (120c) of the light circulator (120).

[0031] The light detector (170) detects the reaction light reflected from the optical fiber grating portion (142).

[0032] The control unit (182) is configured to set supported functions, and the display unit (184) is controlled by the output unit (180) to display display information.

[0033] The output unit (180) controls the operation of the light source (110) and measures the strength of the electric field generated in the area where the optical fiber grating part (142) is installed from the signal received by the light detector unit (170) which is reflected from the optical fiber grating part (142).

[0034] That is, the output unit (180) calculates the electric field strength by moving the wavelength shift information of the light received from the optical fiber grating unit (142), and outputs the calculated electric field strength value through the display unit (184) applied as the output unit.

[0035] Here, in addition to the display unit, the output unit may also include a communication unit that transmits a current value to a destination address.

[0036] That is, as shown in FIG. 3, depending on the strength of the electric field, when the first strength is detected, the reaction light is detected at a wavelength labeled A, and when the second strength is detected, it is detected at a wavelength labeled A', and the wavelength of the reaction light is shifted by the stretching deformation of the piezoelectric element (150) according to the strength of the electric field.

[0037] Accordingly, the output unit (180) is configured to obtain the electric field strength value due to the wavelength shift of the reaction light through experiment, record it in a lookup table, and calculate the electric field strength using the wavelength shift information of the reaction light.

[0038] An electric field strength measuring device utilizing such piezoelectric elements and optical fiber gratings can precisely measure electric fields generated from thunderclouds. In particular, the proposed electric field strength measuring device is compact and has a structure that facilitates the integration of horizontal (Ex, Ey) and vertical electric fields generated by thunderclouds; therefore, it can be effectively utilized not only for measuring the electric fields of thunderclouds but also for measuring the DC electric fields of recently developed HVDC transmission and distribution systems. Furthermore, this device can be easily used for measuring electromagnetic waves.

[0039] The electric field strength measuring device using a piezoelectric element and an optical fiber grating described above offers the advantage of being able to precisely measure electric field strength without being affected by electromagnetic interference by utilizing the optical fiber grating and the piezoelectric element. Explanation of the symbols

[0040] 110: Light source 120: Optical circulator 140: Sensing optical fiber 150: Piezoelectric element 170: Photodetector 180: Output section

Claims

Claim 1 A piezoelectric element that expands and contracts along the direction of an applied electric field; first and second fixing parts that are fixed and spaced apart from each other along the longitudinal direction of the piezoelectric element; a sensing optical fiber that is extended and fixed to the first and second fixing parts, wherein a grating is formed spaced apart from each other along the longitudinal direction of the optical fiber, and the optical fiber grating portion in which the gratings are formed is deformed in response to the expansion and contraction of the piezoelectric element; a light source unit that emits light; an optical circulator that outputs light emitted from the light source unit and input through an input terminal to an output terminal connected to the sensing optical fiber, and outputs reaction light incident in reverse from the sensing optical fiber to a detection terminal; a light detection unit that detects light output from the detection terminal of the optical circulator; and a calculation unit that controls the operation of the light source unit and measures the strength of the electric field in the region where the optical fiber grating portion is installed from a signal received from the light detection unit; wherein the sensing optical fiber is etched along the longitudinal direction such that the optical fiber grating portion in which the gratings are formed is etched so as to leave only a part of the cladding. An electric field strength measuring device using a piezoelectric element and an optical fiber grating, characterized in that the sensing optical fiber is formed to have an etched portion, and the etched portion is maintained in a separated state from the piezoelectric element, and the first and second extension portions, which extend to both sides away from the etched portion and are coupled to the first and second fixing portions, are bonded to the piezoelectric element with a bonding material so that the stretching deformation of the piezoelectric element caused by an applied electric field is concentrated at the etched portion to increase measurement sensitivity, and the bonding material is epoxy. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete

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