WO2013060194A1

WO2013060194A1 - All-optical high-voltage voltage transformer

Info

Publication number: WO2013060194A1
Application number: PCT/CN2012/080854
Authority: WO
Inventors: 张朝阳; 雷林绪; 荆平; 温海燕; 陈祥训; 王成昊
Original assignee: 中国电力科学研究院; 国家电网公司
Priority date: 2011-10-26
Filing date: 2012-08-31
Publication date: 2013-05-02
Also published as: CN102426279B; CN102426279A

Abstract

Provided is an all-optical high-voltage voltage transformer, comprising a high voltage induction apparatus, a shielding insulating apparatus, a sensing head and a photoelectric unit, the high voltage induction apparatus, the shielding insulation apparatus, the sensing head being located at a high voltage side and the photoelectric unit being located at a low voltage side. Light emitted from a light source (10) passes an optical path portion and is divided into two beams of orthogonal linearly polarized light and transmitted to the sensing head through a polarization maintaining fiber (1). Under the effect of an electric field, the sensing head enables the two beams of linearly polarized light to generate a phase difference; and vibration directions of the two beams of linearly polarized lights are respectively rotated by 90 degrees, so that mode exchange of the two beams of light is implemented. The two beams of linearly polarized light returned from the sensing head are transmitted back to the optical path portion for interference through the polarization maintaining fiber (1); and then a circuit portion detects an interference light intensity signal and carries out signal processing; and then, a digital signal is formed and is output.

Description

All-optical high voltage voltage transformer

The invention belongs to the field of voltage transformers, and in particular relates to an all-optical high voltage voltage transformer structure. Background technique

With the development of science and technology, more and more power systems need to be in a high-voltage or ultra-high voltage environment. If the voltage signal is artificially measured, it is very unsafe, so the voltage transformer plays a very important role in the power system. It is one of the basic test equipments that are indispensable for power system monitoring. Usually, the primary side of the voltage transformer is connected to the primary system (for example: high-voltage line), the secondary side is connected to the measuring instrument, and the relay protection device is used. At present, voltage transformers are mainly electromagnetic and non-electromagnetic (such as: electronic, photoelectric), the most widely used is the traditional electromagnetic induction voltage transformer, in some ultra-high voltage fields also used capacitor voltage divider voltage Transformer. With the increase in power demand, the demand for power quality continues to increase, and the power system is developing toward ultra-high voltage and large capacity. This kind of traditional voltage transformer has increasingly exposed its shortcomings in the safe operation of power systems, improving the accuracy of energy measurement and improving the automation of power systems: for example, it is difficult to insulate under high voltage and ultra high voltage, and the insulation structure is complex; The transformer connected to the power grid is equivalent to a nonlinear inductive load. Under certain conditions, it may have ferromagnetic resonance with the system capacitance, and there is ferromagnetic saturation and ferromagnetic resonance, which leads to waveform distortion and large linear error. The transformer is filled with oil, and there is a potential danger of explosion; it is bulky and has amazing quality.

In the prior art, some optical voltage transformers are also disclosed, which have good insulation performance compared with the conventional electromagnetic voltage transformers, although the signal has optical signal transmission; the iron core is not affected by electromagnetic interference, and there is no iron. Hysteresis caused by magnetic resonance, magnetic saturation and large inductance; measuring frequency bandwidth, large dynamic range, and the advantages of closed-loop control without open circuit leading to high voltage. However, due to its structural defects, there are still many problems: For example, the isolation on the high and low voltage sides increases the length of the optical path, introduces optical path noise and interference; since there is no effective insulation of the high and low voltage side structures, if directly exposed to air Medium or insulation treatment is not appropriate, not only has safety hazards, but also measurement structure deviation due to external interference; In addition, the structure of the photoelectric unit can be made more compact and the operation is more convenient. Summary of the invention

In order to overcome the above-mentioned drawbacks of the prior art, the object of the present invention is to provide an all-optical high-voltage voltage transformer capable of achieving high isolation on the high and low voltage sides, high safety, strong anti-interference ability, simple structure and convenient operation.

The all-optical high-voltage voltage transformer of the present invention is realized by the following technical solutions: An all-optical high-voltage voltage transformer comprising a sensing unit on a high voltage side and a photovoltaic unit on a low voltage side, wherein the sensing unit and the photoelectric unit are connected by a polarization maintaining fiber, and is characterized in that:

The sensing unit includes a high voltage sensing device, a shielding insulating device and a sensing head, and the high voltage sensing device senses a high voltage potential from a high voltage line and forms a stable electric field in the shielding insulating device, and the sensing head is placed in the electric field;

The photoelectric unit includes an optical path portion and a circuit portion disposed in the secondary chassis;

The light emitted from the light source is divided into two orthogonal linearly polarized lights through the optical path and transmitted to the sensing head through the polarization maintaining fiber; the sensing head passes the two linearly polarized light through the sensing head under the action of the electric field After the phase difference is generated, after the two linearly polarized lights pass through the sensing head again, the total phase difference is 2^, and the vibration directions of the two linearly polarized lights are respectively rotated by 90° to realize the mode interchange; The two linearly polarized lights returned by the sensing head are transmitted back to the optical path portion through the polarization maintaining fiber for interference, and then the circuit portion detects the interference light intensity signal and performs signal processing to form a digital signal output.

Wherein, the high-voltage induction device comprises a metal guiding rod and a pressure equalizing ball, and the metal guiding rod induces a high-voltage potential from the high-voltage line, and extends a lower portion of the metal guiding rod carrying the high-voltage potential into the shielding insulating device, wherein the metal guiding rod The lower end is provided with a pressure equalizing ball.

Wherein, the shielding insulation device comprises a sealed cylindrical shielding device, and the shielding device is internally filled with SF ₆ gas for insulation.

Wherein, the sensing head comprises a collimating lens, a Faraday rotator and an electro-optic crystal, and two opposite faces of the Faraday rotator are respectively bonded to a light incident surface of the collimating lens and the electro-optical crystal, on the electro-optic crystal, and The other surface opposite to the light incident surface is plated with a reflective film, and the upper and lower end faces of the electro-optic crystal are respectively mounted with electrodes.

Wherein, the polarization maintaining fiber and the sensing head are made of an insulating material, and the sensing head is placed on one side of the metal guiding rod. Wherein, each time the two orthogonal linearly polarized lights pass through the Faraday rotator, their polarization directions are rotated by 45°. Wherein, two orthogonal linearly polarized lights obtained by the optical path portion in the secondary chassis are respectively transmitted along the X-axis and the Y-axis of the polarization-maintaining fiber, and after 45° Faraday rotator, the polarization directions of the two beams are all in the same direction. After being rotated by 45°, it is incident on the electro-optic crystal. The electro-optical crystal generates a linear electro-optical effect under the action of the electric field, causing a phase difference between the two linearly polarized lights. When the two beams are reflected by the reflective film disposed on the end face of the electro-optic crystal, the two beams are After passing through the electro-optic crystal, the phase difference is doubled, that is, the total phase difference is 2 φ, and after passing through the Faraday rotator, the polarization directions of the two beams are rotated by 45° on the basis of the previous rotation, that is, the two beams are rotated respectively. 90°; At this time, the linearly polarized light originally transmitted along the X-axis of the polarization-maintaining fiber is transmitted along the paraxial axis of the polarization-maintaining fiber, and the linearly polarized light originally transmitted along the axis of the polarization-maintaining fiber becomes the X-axis along the polarization-maintaining fiber. Transmission, that is, the exchange of two light modes is realized.

π I

φ = η _η γ, Α]

Wherein, the phase difference generated by the two linearly polarized lights, wherein Ζ is the length of the electro-optic crystal in the direction of light propagation, is the thickness of the electro-optic crystal in the direction of the applied electric field, "is the refractive index of the electro-optic crystal, ^ is an electro-optic crystal of The electro-optic coefficient is the voltage applied to the electro-optic crystal.

Wherein, the optical path portion comprises a light source, a coupler I, a Y-waveguide modulator and a coupler II, and light emitted from the light source is coupled to the Y-waveguide modulator through the coupler I, and is divided into Y-waveguide modulators. Two orthogonal linearly polarized lights, which are coupled by the coupler II and enter the polarization-maintaining fiber and transmitted to the sensing head; after passing through the sensing head, the two beams carrying the information of the voltage to be measured are further along the polarization maintaining The fiber returns, coupled by the coupler II, and interferes at the Y-waveguide modulator. After the interference, the interfering light intensity signal is coupled via the coupler I, and then enters the circuit portion for signal processing.

Wherein, the circuit part comprises:

a photodetector for detecting an interference light intensity signal emitted by the optical path portion, and converting the signal into an analog voltage signal, and sending the signal to an analog to digital converter;

The analog-to-digital converter converts the analog voltage signal into a discrete digital signal and sends it to the digital signal processing unit; the digital-to-analog converter converts the digital staircase wave generated by the digital signal processing unit into an analog staircase wave;

a driving circuit that drives an Y-waveguide modulator that simulates a step wave applied to the optical path portion;

The digital signal processing unit is configured to perform data demodulation on the digital signal, and generate a step wave step height by an integral control algorithm, and accumulate to form a digital staircase wave, and send it to a digital-to-analog converter to convert into an analog step wave, and drive the circuit The Y-waveguide modulator applied to the optical path portion implements closed-loop control; the digital signal processing unit is further configured to generate a modulated square wave, which is converted into an analog square wave by a square wave driving circuit, and then superimposed with the analog staircase wave And then applied to the Y-waveguide of the optical path portion; the digital signal processing unit is further configured to smooth-filter the digital signal to form a digital signal output.

The digital signal processing unit includes a digital signal processor (hereinafter referred to as DSP) and a field programmable gate array (hereinafter referred to as FPGA).

The beneficial effects of the invention are -

1. The transformer of the invention adopts an optical component as a sensing head on the high voltage side, and the photoelectric unit is placed on the low voltage side in the secondary chassis, and the signal is transmitted through the polarization maintaining optical fiber in the middle, so that the insulation structure is greatly simplified, and the high and low voltage are realized. The complete isolation of the side has the advantages of high safety, small size, light weight, etc., and is easy to realize network and digitization; and there is no iron core in the transformer, and there are no problems such as magnetic saturation and ferromagnetic resonance.

2. The shielding device of the invention adopts SF ₆ gas as the insulating medium, and does not cause fire, explosion and the like; the sensing head and the polarization maintaining optical fiber are both made of insulating material and small in size, so that the insulating structure is greatly simplified, and the realization is high, Complete isolation on the low pressure side for high safety.

3. The sensing head of the invention is mainly formed by integrating a Faraday rotator and an electro-optic crystal, which is small in size and light in weight, and is convenient for field use. In addition, by using a reflective film on one side of the electro-optic crystal, the reflective film is utilized. Reflective light The optical rotation effect of the road and the Faraday rotator achieves the reciprocity of the optical path in the transformer, which makes the optical path have higher anti-interference ability. 4. The photoelectric unit of the invention has the advantages of wide frequency response, large dynamic range, fast response speed, digital output, high measurement accuracy and the like. DRAWINGS

1 is a schematic structural view of an all-optical high voltage voltage transformer of the present invention;

2 is a schematic structural view of a sensing head;

Figure 3 is a schematic view showing the structure of the optical path portion;

Figure 4 is a schematic diagram showing the structure of the circuit portion;

In the figure, 1-polarization fiber, 2-metal guide, 3-pressure ball, 4-shield, 5-Faraday rotator, 6-electro-optic crystal, 7-reflection film, 8-electrode, 9-second Chassis, 10-source, 11-coupler I, 12-Y waveguide modulator, 13-coupler II, 14-photodetector, 15-analog converter, 16-digital signal processing unit, 17-digital to analog converter , 18-drive circuit, 19-high voltage line, 20-sensor head, 21-collimator lens, 22-square wave drive circuit. detailed description

The all-optical high-voltage transformer of the present invention will be further described in detail below with reference to the accompanying drawings.

The all-optical high-voltage voltage transformer of the present invention is mainly composed of three parts: a sensing unit located on the high voltage side, a photoelectric unit located on the low voltage side, and a polarization maintaining optical fiber connecting the sensing unit and the photoelectric unit.

As shown in FIG. 1, the sensing unit includes a high voltage sensing device, a shielding insulating device, and a sensing head.

The high-voltage induction device includes a metal guide rod 2 and a pressure equalizing ball 3. The shield insulation device includes a sealed cylindrical shield device 4 and SF ₆ gas charged into the shield device for insulation. The metal guiding rod 2 induces a high voltage potential from the high voltage line 18, and the lower part of the metal guiding rod 1 carrying the high voltage potential is inserted into the shielding device 4. The lower end of the metal guiding rod is equipped with a pressure equalizing ball 3, and the shielding device is filled with SF ₆ gas for insulation. A stable electric field will be generated inside the enclosed space.

The sensing head is fixed on one side of the metal guiding rod 2 located inside the shielding device. As shown in FIG. 2, the sensing head is mainly composed of a collimating lens 21, a Faraday rotator 5 and an electro-optical crystal 6, and two of the Faraday rotator 5 The opposite faces are respectively bonded to the front end surface of the collimator lens 21 and the electro-optical crystal 6 (ie, the light incident surface), and the reflective film 7 is plated on the electroluminescent substrate on the rear end surface opposite to the front end surface, and the electro-optical crystal 6 is on the upper surface. The lower end faces are respectively provided with electrodes 8. The electrode 8 of the electro-optic crystal induces a potential in the electric field and adopts lateral modulation, that is, the direction of the electric field applied to the electro-optic crystal 6 is perpendicular to the direction of light propagation. The working principle of the sensing head is: two orthogonal linearly polarized lights obtained from the optical path portion of the secondary chassis 9 are respectively transmitted along the X-axis and the Y-axis of the polarization maintaining fiber, and after passing through the 45 ° Faraday rotator 5, The polarization directions of the two beams are all rotated through 45 degrees in the same direction. Then they are incident on the electro-optic crystal 6, which produces an electro-optical effect under the action of an external electric field, so that the two beams produce a certain phase. Poor ^. Where / is the length of the crystal in the direction of light propagation, which is the thickness of the crystal in the direction of the applied electric field, ". is the refractive index of the crystal, which is the electro-optic coefficient of the crystal, which is the voltage applied to the crystal. After being reflected by the reflective film 7, The two beams of light pass through the electro-optic crystal 6 again, and the phase difference is doubled, that is, the total phase difference is 2 ^. The two beams of light outgoing light crystal 6 pass through the Faraday rotator 5 again, according to the non-reciprocity of the Faraday effect, the two beams The direction of vibration is further rotated by 45 degrees in the previous direction of rotation, so that they each rotate by 90 degrees. At this time, the light originally propagating along the X-axis of the polarization-maintaining fiber becomes propagating along the Y-axis of the polarization-maintaining fiber, which is originally along the polarization-maintaining fiber. The light propagating in the Y-axis is propagated along the X-axis of the polarization-maintaining fiber, and the mode is interchanged. Then, the polarization-maintaining fiber 1 is transmitted back, and the optical path portion and the circuit portion of the secondary chassis 9 acquire the interference light of the two beams. Strong detection and signal processing. Due to the two beams of interference, the X-axis and Y-axis of the polarization-maintaining fiber are respectively passed during the optical path transmission, but only slightly different in time, so returning to photo-detection An optical-optical crystal carries only phase modulation information thereof.

The photovoltaic unit on the low voltage side includes an optical path portion and a circuit portion placed in the secondary chassis 9.

As shown in Fig. 3, the optical path portion is mainly composed of a light source 10, a coupler 1 11, a Y-waveguide modulator 12, and a coupler II 13. The working principle is as follows: The light emitted by the light source 10 passes through the coupler I 11 and enters the Y-waveguide modulator 12. The Y-waveguide modulator, also known as the integrated optical phase modulator, is a multifunctional device consisting of a Y-beam splitter and The two phase modulators are used, and the Y-waveguide modulator can make the mechanism of the optical path portion more compact, reduce the volume of the secondary chassis, and operate more conveniently. The light entering the Y-waveguide is split into two beams by the Y-beam splitter and modulated into two orthogonal linearly polarized lights by two phase modulators. The two bundles of linearly polarized light enter the polarization-maintaining fiber 1 through the coupler II 13 , transmitted to the sensor head along the two transmission modes of the polarization maintaining fiber 1. After passing through the sensing head, the two linearly polarized lights carrying the voltage information to be tested return along the original optical path, interference occurs at the Y-waveguide modulator 12, and then coupled into the photodetector 14 of the circuit portion by the coupler 11 and Signal processing is performed in the circuit section.

As shown in FIG. 4, the circuit portion is mainly composed of a photoelectric converter 14, an analog-to-digital converter 15, a digital signal processing unit 16, a digital-to-analog converter 17, and a corresponding driving circuit 18. The signal processing process is: the photodetector 14 detects the interference light intensity signal carrying the voltage information to be tested from the optical path portion, and converts the signal into a voltage signal, and then transmits the signal to the analog-to-digital converter 15 to convert the voltage signal into discrete signals. The digital signal is sent to a digital signal processing unit 16, which is implemented by a DSP and an FPGA. The FPGA demodulates the discrete digital signal, integrates the demodulation result, generates the stepped step height, and then accumulates to form a digital staircase wave, which is sent to the digital-to-analog converter 17 to be converted into an analog staircase wave, and is driven by the driving circuit 18. The Y-waveguide modulator 12 applied to the optical path portion realizes closed-loop control; the FPGA also generates a modulated square wave, which is converted into an analog square wave by the square wave drive circuit 22, and superimposes the analog square wave with the analog staircase wave, and applies it to The Y-waveguide modulator 12; in addition, the DSP smoothes the demodulated data of the FPGA, and the digital signal is output by the FPGA. After that, you can use the existing The measuring device indirectly measures the voltage information to be measured, that is, the electric field size, by measuring the output digital signals of the two beams. The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to be limiting, and various modifications and changes can be made thereto without departing from the scope of the present invention. It is intended to be within the scope of the claims of the appended claims.

Claims

Rights request

An all-optical high-voltage voltage transformer comprising a sensing unit on a high voltage side and a photovoltaic unit on a low voltage side, wherein the sensing unit and the photoelectric unit are connected by a polarization maintaining fiber (1), and the characteristics thereof Lie in:

The photovoltaic unit includes an optical path portion and a circuit portion disposed in the secondary chassis (9);

The light emitted from the light source is divided into two orthogonal linearly polarized lights through the optical path and transmitted to the sensing head through the polarization maintaining fiber; the sensing head passes the two linearly polarized light through the sensing head under the action of the electric field After the phase difference is generated, after the two linearly polarized lights pass through the sensing head again, the total phase difference is 2 p, and the vibration directions of the two linearly polarized lights are respectively rotated by 90° to realize the mode interchange; The two linearly polarized lights returned by the sensing head are transmitted back to the optical path portion through the polarization maintaining fiber for interference, and then the circuit portion detects the interference light intensity signal and performs signal processing to form a digital signal output.

2. The all-optical high voltage voltage transformer according to claim 1, wherein: said high voltage sensing device comprises a metal guiding rod (2) and a pressure equalizing ball (3), said metal guiding rod inducing a high voltage potential from the high voltage line The lower part of the metal guiding rod (2) carrying the high voltage potential extends into the shielding insulation device, and the lower end of the metal guiding rod is provided with a pressure equalizing ball (3).

3. An all-optical high voltage voltage transformer according to claim 1 or 2, characterized in that the shielding insulation comprises a sealed cylindrical shielding device (4), the shielding device (4) being internally filled with 8? ₆ gas is insulated.

4. The all-optical high voltage voltage transformer according to claim 1, wherein: said sensing head comprises a collimating lens (21), a Faraday rotator (5) and an electro-optic crystal (6), said Faraday rotator The opposite faces of the mirror (5) are respectively bonded to the light incident faces of the collimating lens (21) and the electro-optical crystal (6), and the reflective film is coated on the other surface of the electro-optic crystal opposite to the light incident surface (7). The upper and lower end faces of the electro-optic crystal (6) are respectively provided with electrodes (8).

The all-optical high-voltage voltage transformer according to claim 4, wherein: the polarization maintaining fiber and the sensing head are made of an insulating material, and the sensing head is placed on one of the metal guiding rods (2) side.

The all-optical high-voltage voltage transformer according to claim 4, characterized in that: each time the two orthogonal linearly polarized lights pass through the Faraday rotator (5), their polarization directions are rotated by 45°.

7. The all-optical high voltage voltage transformer of claim 4, wherein: the two orthogonal linearly polarized lights obtained by the optical path portion of the secondary chassis (9) are respectively along the X-axis of the polarization maintaining fiber Y-axis transmission, after 45° Faraday rotator (5), the polarization directions of the two beams are rotated 45° in the same direction and then incident on the electro-optic crystal (6). The electro-optic crystal produces a linear electro-optic effect under the electric field, so that The beam-polarized light produces a phase difference. When the two beams are reflected by the reflective film (7) disposed on the end face of the electro-optic crystal, the two beams pass through the electro-optic crystal, and the phase difference is doubled, that is, the total phase difference is 2^, and then Passing through the Faraday rotator (5), the polarization directions of the two beams are further rotated by 45° on the basis of the previous rotation, that is, the two beams are each rotated by 90°; at this time, initially transmitted along the X-axis of the polarization-maintaining fiber. The linearly polarized light is transmitted along the Y-axis of the polarization-maintaining fiber, and the linearly polarized light originally transmitted along the Y-axis of the polarization-maintaining fiber is transmitted along the X-axis of the polarization-maintaining fiber, that is, the interchange of the two optical modes is realized.

8. The all-optical high voltage voltage transformer of claim 1 or 7, wherein:

π I 3

φ = η ₍₎ γ, Χ]

The phase difference ^d produced by the two linearly polarized lights, wherein ⁷ is the length of the electro-optic crystal in the direction of light propagation, and is the thickness of the electro-optic crystal in the direction of the applied electric field, "is the refractive index of the electro-optic crystal, and is the electro-optic coefficient of the electro-optic crystal. , is the voltage applied to the electro-optic crystal.

9. The all-optical high voltage voltage transformer according to claim 1, wherein: said optical path portion comprises a light source (10), a coupler I (11), a Y-waveguide modulator (12) and a coupler II (13) The light emitted from the light source (10) is coupled to the Y-waveguide modulator (12) via the coupler I (11), and is split into two orthogonal linearly polarized lights in the Y-waveguide modulator. After being coupled by coupler II (13), the light enters the polarization maintaining fiber (1) and is transmitted to the sensing head. After passing through the sensing head, the two beams carrying the voltage information to be tested are returned along the polarization maintaining fiber, and passed through the coupler. II ( 13 ) Coupling, interference occurs at the Y-waveguide modulator (12), and the interfering interference light intensity signal is coupled via the coupler I (11), and then enters the circuit portion for signal processing.

The all-optical high-voltage voltage transformer according to claim 1 or 9, wherein: said circuit portion comprises a photodetector (14) for detecting an interference light intensity signal emitted from the optical path portion, and the signal is Converted to an analog voltage signal, sent to an analog to digital converter (15);

An analog-to-digital converter (15) converts the analog voltage signal into a discrete digital signal and sends it to the digital signal processing unit

(15);

a digital-to-analog converter (17) that converts a digital staircase wave generated by the digital signal processing unit into an analog staircase wave; a driving circuit (18) that drives a Y-waveguide modulator (12) that applies an analog staircase wave to the optical path portion; and a digital signal The processing unit (16) is configured to perform data demodulation on the digital signal, and after the integral processing, generate the step wave step height, and accumulate to form a digital staircase wave, and send it to the digital-to-analog converter (17) to convert into an analog staircase wave. The Y-waveguide modulator (12) is applied to the optical path portion through the driving circuit (18) to implement closed-loop control; the digital signal processing unit (16) is further configured to generate a modulated square wave, and the modulated square wave passes through the square wave driving circuit. (22) converting into an analog square wave, superimposing with the analog staircase wave, and then applying to the Y-waveguide modulator (12) of the optical path portion; the digital signal processing unit (16) is also used for smoothing the digital signal After that, a digital signal output is formed.

11. The all-optical high voltage voltage transformer of claim 10, wherein: said digital signal processing unit

(16) Includes digital signal processor (DSP) and field programmable gate array (FPGA).