CN102222558B - Optical current mutual inductor and optoelectronic information processor thereof - Google Patents

Abstract

The invention relates to the improvement of the optical current transformer. The basic optical path is fixed in the inner cavity of the ring conductor (1) through which the measured current passes, and the input self-focusing lens (6), polarizer (7), and sensor head are input according to the order of light passing. (2), analyzer (9) and output self-focusing lens (10), optical fiber (8) (11) is supported to low-voltage side through insulation, connects photoelectric information processor, and photoelectric information processor includes light source (29), can control current source (40), photoelectric converter (27), AC-DC separator (41), the AC signal output by the AC-DC separator is the output signal of the current transformer, and the DC signal is input to the feedback processor (42), and the feedback The processor is connected to the input terminal of the controllable current source, controls the light intensity of the light source according to the feedback information, overcomes the influence of factors such as temperature, and improves the measurement accuracy of the optical current transformer. The photoelectric information processor can be used in various sensing forms of optical current transformers to improve the measurement accuracy.

Description

Optical current transformer and its photoelectric information processor

technical field

The invention relates to the improvement of the optical current transformer used in the current measurement and control of the high-voltage line of the power system, in particular to the improvement of the optical current transformer with magneto-optic material as the main sensing device.

Background technique

The current transformer is an important equipment for power system measurement and protection control. After long-term development, the accuracy of the electromagnetic current transformer in measuring the steady-state current can reach a few ten thousandths, or even higher; but in the case of a short-circuit fault, the electromagnetic current transformer Severe magnetic saturation occurs in the relay, which leads to the distortion of the secondary output current waveform and cannot describe the transition process of the short-circuit current. This is one of the main reasons for the relay protection to malfunction and refuse to operate. In the future, the monitoring and control of the power system will move towards a full-time process, from local to global. Maloperation and refusal of relay protection will bring catastrophic accidents to the power system. Therefore, people are building a security defense system for the power system. The traditional electromagnetic current transformer cannot reflect the dynamic process of the power grid, and a new type of current transformer is urgently needed. Therefore, the optical current transformer based on the Faraday magneto-optical effect has been paid attention to, especially the bulk optical current transformer. On May 16, 2007, the Chinese Patent Office published an invention patent specification with the application number 200510117694.8 titled "Optical Current Transformer and Its Method for Measuring Current". Its technical scheme is: the sensing head is a straight magneto-optical material, the input optical fiber, the input self-focusing lens, the polarizer, the optical sensing head, the polarizer, the parallel output self-focusing lens, the optical fiber and the vertical The output self-focusing lens and optical fiber constitute the basic optical path. The current to be measured passes through the ring conductor, and establishes a parallel magnetic field in its cavity. There is at least one basic optical path in the magnetic field, and its sensing head is parallel to the magnetic field lines. When there are multiple optical paths, each sensing head has the same length and is equidistant from the axis of the ring conductor. The output optical fiber of each optical path is connected to two photoelectric converters on the low-voltage side, and outputs parallel voltage signals and vertical voltage signals to calculate the measured current. The polarized light in the sensor head of the invention passes through directly, which overcomes the optical path defect of the "optical current transformer" type optical current transformer, and will not be unstable due to the denaturation of the reflective surface. The transformer can run stably for a long time and has high measurement accuracy; however, the invention still has shortcomings, which are manifested in: the basic optical path and the vertical polarization optical path, once the vertical self-focusing lens is not perpendicular to the main axis, or the vertical self-focusing If there is a difference in performance between the lens and the parallel self-focusing lens, the accuracy of the output result will be affected. Although temperature correction can be performed when there are multiple optical paths, the effect of temperature correction is very small. When the temperature and the stress of the sensor head change, the measurement value will still have a large error. The basic optical path is susceptible to environmental pollution during the process and operation, which will also affect the measurement accuracy. To sum up, the measurement accuracy of the optical current transformer is not high enough.

Contents of the invention

The technical problem to be solved by the present invention is to provide an optical current transformer to further improve the measurement accuracy of the optical current transformer.

In order to solve the above technical problems, the optical current transformer provided by the present invention: comprises an insulator, a conductor for the measured current to pass through, an optical sensing head, a polarizer, a polarizer, and an optical lens; The conductor is a ring conductor that forms a magnetic field parallel to the magnetic force lines in its inner cavity when the current passes through; the optical sensor head is a straight magneto-optical material whose length is much smaller than the length of the ring conductor in the axial direction. The two end faces of the head are planes perpendicular to the length direction; the optical sensor head and its related components constituting the basic optical path are fixed in the cavity of the ring conductor with an insulating object, and the optical sensor head is parallel to the axis of the ring conductor, and Located in the middle of the cavity along the axial direction, in the region of parallel magnetic lines of force; the input optical fiber and output optical fiber pass through the middle hole of the insulator to the low-voltage side;

There is at least one basic optical path in the inner cavity of the ring conductor for the current to be measured. The optical sensor head and its related optical elements are arranged along a straight line to form the basic optical path. These elements are arranged in the order of light passing: input optical fiber, input self Focusing lens, polarizer, optical sensor head, analyzer, output self-focusing lens, output fiber; the polarization plane of the analyzer relative to the polarizer rotates 40 degrees to 50 degrees around the axis of the sensor head, the above basic optical path Installed and sealed in a metal shell with good thermal conductivity; the input optical fiber and the output optical fiber are led out of the metal shell, and a photoelectric information processor is installed on the low-voltage side. The photoelectric information processor includes a photoelectric converter, an AC/DC separator, a feedback processor, Control the current source and light source, the information is transmitted in the above order, the AC-DC separator outputs two kinds of electrical signals, AC and DC, in which the AC signal is the output signal of the optical current transformer; the DC signal is input to the feedback processor, and the feedback processor’s The output is connected to the input of a controllable current source.

The AC-DC separator includes a DC-blocking amplifier and a photoelectric subtractor. The DC-blocking amplifier receives the voltage signal from the photoelectric converter, passes through the DC-blocking and passes through the AC voltage and then amplifies it and then outputs it to the outside, that is, the output of the optical current transformer. , and output to the photoelectric subtractor inwardly, and the photoelectric subtractor also receives the voltage signal transmitted from the photoelectric converter, and subtracts the two to obtain a DC voltage signal; the feedback processor includes a photoelectric amplifier, a photoelectric CPU and a reference The voltage source, the reference voltage source is connected to the photoelectric CPU, the reference voltage source is the built-in voltage source of the photoelectric CPU, the photoelectric amplifier receives the DC voltage signal output from the photoelectric subtractor, amplifies the voltage signal, and outputs it to the photoelectric CPU, photoelectric CPU According to the DC voltage signal, analyze and calculate, and output digital signal instructions; the controllable current source includes a light source, an adjustable reference voltage source and a digital potentiometer, the adjustable reference voltage source supplies power to the light source, and the digital potentiometer receives the output of the photoelectric CPU The digital signal command converts it into a voltage signal and outputs it to the adjustable reference voltage source. The adjustable reference voltage source changes the output voltage according to the voltage signal from the digital potentiometer, and then changes the current intensity input to the light source, that is, Changed the intensity of the light emitted by the light source.

The model of the adjustable reference voltage source in the photoelectric information processor is MAX8880, the model of the light source is HFBR1414, the model of the digital potentiometer is X9110, the first pin of the adjustable reference voltage source in the controllable current source A capacitor C1 is connected in series with the second pin, a resistor R1 is connected in series between the first pin and the fifth pin of the adjustable reference voltage source, and a capacitor is connected in series between the third pin of the adjustable reference voltage source and the ground wire C2, resistor R2 connected in series between the 3rd pin of the adjustable reference voltage source and the 2nd pin of the light source, the 3rd pin of the adjustable reference voltage source is connected to the 3rd pin of the digital potentiometer, the adjustable reference voltage The 3rd pin of the source is connected to the 17th pin of the digital potentiometer, the positive input terminal of the operational amplifier U3 is connected to the 1st pin of the digital potentiometer, and the negative input terminal of the operational amplifier U3 is connected to the 7th tube of the digital potentiometer The output terminal of the operational amplifier U3 is connected to the 7th pin of the digital potentiometer, the positive input terminal of the operational amplifier U4 is connected to the 19th pin of the digital potentiometer, and the negative input terminal of the operational amplifier U4 is connected to the digital potentiometer. The 11th pin is connected, and the output terminal of operational amplifier U4 is connected with the 11th pin of digital potentiometer; The 61st pin and the 62nd pin of the photoelectric CPU in the described feedback processor are respectively connected with the 9th pin of digital potentiometer The pins are connected to the 14th pin, the reference voltage source is the built-in voltage source in the photoelectric CPU, the operational amplifier U6 and the resistors R3, R4, Rf together form a photoelectric amplifier, and the output of the photoelectric amplifier is connected to the 18th pin of the photoelectric CPU; The input terminal P51 in the AC-DC separator is connected with the output terminal of the photoelectric converter, the operational amplifier U51 forms a DC blocking amplifier with the capacitor C51, the resistor R51, and the resistor R52, and one end of the capacitor C51 is connected with the input terminal P51, and the operational amplifier U52 Resistor R53, resistor R54, and resistor R55 form a photoelectric subtractor. The input end of the photoelectric subtractor, that is, the other end of the resistor R53 and the resistor R54, is respectively connected to the output terminal of the DC blocking amplifier and the input terminal P51 of the AC-DC separator. The output terminal P52 is connected to the input terminal P5 of the feedback processor, and the output terminal P53 is the output terminal of the optical current transformer.

The metal shell is cylindrical, and the inside is a through hole, the aperture matches the outer diameter of the cylindrical sensor head, polarizer, and polarizer. There is a section of conical surface at the outer end of each segment thread, the central hole and the conical surface have the same center line, and there are two conical end caps, the outer part of which is a conical surface matching the metal shell, and the middle part of the end cap is the same as the conical surface. The outer conical surface has a tapered hole with the same center line, and the tapered hole matches the shape of the polarizer and analyzer;

The sensor head is installed in the middle of the inner hole, and a ring-shaped elastic washer is placed on each side. The outer edge of the elastic washer is respectively installed with a polarizer and an analyzer. The polarization directions of the two are relatively rotated by 40 to 50 degrees. Fix the above components with fixing rings with external threads respectively, and install the end caps into the conical surfaces at both ends of the metal shell respectively. The conical surfaces are bonded with quick-drying glue. The self-focusing lenses are respectively installed in the tapered holes of the two end caps, the input self-focusing lens and the output self-focusing lens protrude from the thin end of the end cap, the tapered surface is bonded with quick-drying glue, and the outermost end of the tapered hole is sealed Sealed with glue, the outermost ends protrude from the input optical fiber and the output optical fiber respectively.

The metal shell is cylindrical, with a through hole inside, and the aperture matches the outer diameter of the cylindrical sensing head, polarizer, and polarizer. There is a section of thread at both ends of the hole, and the metal shell Each of the two end sections has at least three screw holes uniformly distributed along the circumference in the same cross section and radiating outward from the center of the metal shell. There are adjusting and fixing screws sunk into the screw holes in the screw holes, and there are two end covers. The end cap is a cylinder whose outer diameter is slightly smaller than the inner diameter of the end of the metal shell, and its center is a round hole matching the outer diameter of the cylindrical input self-focusing lens and output self-focusing lens; the sensor head is installed in the middle of the inner hole , a ring-shaped elastic washer is placed on each side, and the outer sides of the elastic washer are respectively loaded into the polarizer and the analyzer, and the polarization directions of the two are rotated by 40 to 50 degrees relative to each other, and the outer sides of the two sides are respectively used with external threads. The fixing ring fixes the above components, the input self-focusing lens and the output self-focusing lens are respectively installed in the center hole of the end cover, and glued with quick-drying glue, and the end covers are respectively installed in the round holes at both ends of the metal shell, and fixed with the adjustment It is fixed by screws, the outermost end of the round hole is sealed with sealant, and the outermost end protrudes from the input optical fiber and the output optical fiber.

The above-mentioned photoelectric information processor can be used as an independent device, in addition to being used in the optical current transformer, it can also be used in various types of optical current transformers to improve measurement accuracy.

Compared with prior art, the beneficial effects of the present invention are as follows:

1. The photoelectric information processor is used on the low-voltage side, which not only replaces the function of the vertical optical path, but also eliminates the change in the measurement accuracy of the optical current transformer caused by temperature and stress due to the closed-loop negative feedback structure. The closed-loop negative feedback structure overcomes the The shortcomings of the error accumulation of each element in the open-loop structure of the prior art further improve the measurement accuracy.

2. Since the vertical optical path is canceled in the basic optical path, the problem of affecting the measurement accuracy caused by the existence of the vertical optical path in the prior art is overcome, thereby improving the measurement accuracy.

3. The basic optical path is sealed with a metal shell, which can prevent pollution during the process and operation, and also improves the accuracy of the optical current transformer.

4. The interface through which light passes in the basic optical path is not bonded with optical glue, and the positions of the components are relatively fixed, and there is no contact between the components, which prevents the components from contacting each other and causing scratches on the incident surface, thus improving the optical current. The operation stability and measurement accuracy of the transformer.

5. Since the end of the metal shell and the end cover, the self-focusing lens and the central hole of the end cover adopt a conical structure, the basic optical path is easy to achieve alignment, and the assembly of the basic optical path can be realized without a special optical platform, which is convenient for production.

6. Since the vertical optical path is canceled in the basic optical path, the metal shell can be directly inserted into the through hole in the center of the cylindrical insulating object, which simplifies the production process.

graphic description

Figure 1 Schematic diagram of the structure of the optical current transformer,

The structural schematic diagram of the photoelectric information processor of Fig. 2,

Figure 3. Circuit schematic diagram of a controllable current source,

Figure 4. Circuit schematic diagram of the feedback processor,

The schematic circuit diagram of the AC-DC separator in Fig. 5,

Fig. 6 is a schematic structural view of the metal shell 1,

Fig. 7 is a schematic structural view of the metal shell 2,

Fig. 8 Structural schematic diagram of the optical current transformer sensing part of the solenoid type single optical path,

Fig. 9 Schematic diagram of the structure of the solenoid optical current transformer installed on site,

Figure 10 Ω busbar type two optical path optical current transformer sensing part B-B sectional view,

Figure 11 A-A cross-sectional view of the sensing part of the optical current transformer with two optical paths of the Ω busbar type,

Figure 12 Schematic diagram of the structure of the Ω-bus optical current transformer installed on site.

1-1 solenoid, 1-2 ring bus, 2 sensing head, 3 insulating object, 4 through hole, 5 longitudinal groove, 6 input self-focusing lens, 7 polarizer, 8 input optical fiber, 9 analyzer, 10 output self-focusing lens, 11 output optical fiber, 12 metal shell, 13 end groove, 14 epoxy resin barrel, 15 flat flange, 16 groove, 17 epoxy resin rod, 18 manifold, 19 shell, 20 gland , 21 insulator, 22 base box, 23 photoelectric information processor, 24 clamping belt, 25 insulating sleeve, 26 conductive rod, 27 photoelectric converter, 29 light source, 30 cylinder, 31 flat plate, 32 adjusting fixing screw, 33 insulating block , 34 splint, 35 pressure plate, 36 support plate, 37 insulating pad, 38 shell cover, 39 insulating sheet, 40 controllable current source, 41 AC-DC separator, 42 feedback processor, 43 photoelectric amplifier, 44 photoelectric CPU, 45 reference Voltage source, 46 DC blocking amplifier, 47 photoelectric subtractor, 48 adjustable reference voltage source, 49 digital potentiometer, 50 elastic washer, 51 fixing ring, 52 end cap.

detailed description

Specific embodiment one: the photoelectric information processor of the optical current transformer, see Fig. 2, Fig. 3, Fig. 4, Fig. 5.

The photoelectric information processor 23 includes a photoelectric converter 27, an AC/DC separator 41, a feedback processor 42, a controllable current source 40, and a light source 29. The information is transmitted in the above order, and the photoelectric converter 27 receives the optical current transmitted by the output optical fiber. The light intensity signal of the transformer is converted into a voltage signal and output to the AC-DC separator 41, and the AC-DC separator 41 outputs two kinds of electrical signals, AC and DC, wherein the AC signal is the output signal of the optical current transformer, and its DC signal input To the feedback processor 42, the DC signal carries the change information of the output light intensity of the optical sensor head when the temperature and stress change, and is processed by the feedback processor 42, and the processing information is transmitted to the controllable current source 40; the feedback processor 42 The output of the controllable current source 40 is connected to the input end of the controllable current source 40, and the current intensity provided to the light source 29 is adjusted according to the processing information, thereby changing the luminous intensity of the light source 29, that is, adjusting the input light input to the basic optical path through the input optical fiber 8 Strength; according to the principle of negative feedback, the output error of the optical current transformer caused by temperature and stress changes is overcome, and the measurement accuracy of the optical current transformer is improved.

The AC-DC separator 41 includes a DC-blocking amplifier 46 and a photoelectric subtractor 47. The DC-blocking amplifier 46 receives the voltage signal from the photoelectric converter 27, and through the DC-blocking, the AC voltage is amplified and then output to the outside, that is, the optical The output of the current transformer is output to the photoelectric subtractor 47 inwardly, and the photoelectric subtractor 47 also receives the voltage signal transmitted from the photoelectric converter 27, and the two are subtracted to obtain a DC voltage signal; the feedback processor 42 comprises photoelectric amplifier 43, photoelectric CPU44 and reference voltage source 45, and reference voltage source 45 is connected on the photoelectric CPU44, and reference voltage source 45 is the built-in voltage source of photoelectric CPU44, is used for providing reference voltage when photoelectric CPU carries out analog/digital conversion signal, the photoelectric amplifier 43 receives the DC voltage signal output from the photoelectric subtractor 47, amplifies the voltage signal, and outputs it to the photoelectric CPU44, and the photoelectric CPU44 performs analysis and calculation according to the DC voltage signal to obtain the change of the linear birefringence δ, and then Calculate the proportional coefficient of the optical current transformer as the temperature changes, then calculate the digital adjustment instruction, and output the digital adjustment instruction; the controllable current source 40 includes a light source 29, an adjustable reference voltage source 48 and a digital potentiometer 49, The adjustable reference voltage source 48 supplies power to the light source 29, and the digital potentiometer 49 receives the digital adjustment command output by the photoelectric CPU44 and converts it into a voltage signal, and outputs it to the adjustable reference voltage source 48. The transmitted voltage signal changes the output voltage, and further changes the intensity of the current input to the light source 29 , thus changing the intensity of light emitted by the light source 29 .

The model of the adjustable reference voltage source 48 in the photoelectric information processor 23 is MAX8880, the model of the light source 29 is HFBR1414, the model of the digital potentiometer 49 is X9110, the adjustable reference voltage source in the controllable current source 40 A capacitor C1 is connected in series between the first pin and the second pin of 48, a resistor R1 is connected in series between the first pin and the fifth pin of the adjustable reference voltage source 48, and the third pin of the adjustable reference voltage source 48 A capacitor C2 is connected in series with the ground wire, a resistor R2 is connected in series between the third pin of the adjustable reference voltage source 48 and the second pin of the light source 29, and the third pin of the adjustable reference voltage source 48 is connected to a digital potential The 3rd pin of device 49, the 3rd pin of adjustable reference voltage source 48 is connected to the 17th pin of digital potentiometer 49, the positive input terminal of operational amplifier U3 is connected with the 1st pin of digital potentiometer 49, The negative input terminal of the operational amplifier U3 is connected with the 7th pin of the digital potentiometer 49, the output terminal of the operational amplifier U3 is connected with the 7th pin of the digital potentiometer 49, and the positive input terminal of the operational amplifier U4 is connected with the digital potentiometer 49. The 19th pin is connected, and the negative input terminal of operational amplifier U4 is connected with the 11th pin of digital potentiometer 49, and the output end of operational amplifier U4 is connected with the 11th pin of digital potentiometer 49; Described in the feedback processor 42 The 61st pin and the 62nd pin of the photoelectric CPU44 are connected with the 9th pin and the 14th pin of the digital potentiometer 49 respectively, and the reference voltage source 45 is a built-in voltage source in the photoelectric CPU44, which is used to simulate in the photoelectric CPU44 Reference voltage signal is provided during digital conversion, operational amplifier U6 and resistance R3, R4, Rf form photoelectric amplifier 43 jointly, the output of photoelectric amplifier 43 is connected to the 18th pin of photoelectric CPU44; The terminal P51 is connected with the output terminal of the photoelectric converter, the operational amplifier U51, the capacitor C51, the resistor R51 and the resistor R52 form a DC blocking amplifier 46, one end of the capacitor C51 is connected with the input terminal P51, the operational amplifier U52 is connected with the resistor R53, the resistor R54, the resistor R55 constitutes the photoelectric subtractor 47, the input end of the photoelectric subtractor 47, namely the other end of the resistor R53 and the resistor R54, is connected with the output terminal of the DC blocking amplifier 46 and the input terminal P51 of the AC-DC separator 41 respectively, and the output terminal P52 is connected with the feedback processing The input terminal P5 of the device 42 is connected, and the output terminal P53 is the output terminal of the optical current transformer.

The model of the adjustable reference voltage source 48 in the photoelectric information processor 23 is MAX8880, the model of the light source 29 is HFBR1414, the model of the digital potentiometer 49 is X9110, the adjustable reference voltage source in the controllable current source 40 A capacitor C1 is connected in series between the first pin and the second pin of 48, a resistor R1 is connected in series between the first pin and the fifth pin of the adjustable reference voltage source 48, and the third pin of the adjustable reference voltage source 48 A capacitor C2 is connected in series with the ground wire, a resistor R2 is connected in series between the third pin of the adjustable reference voltage source 48 and the second pin of the light source 29, and the third pin of the adjustable reference voltage source 48 is connected to a digital potential The 3rd pin of device 49, the 3rd pin of adjustable reference voltage source 48 is connected to the 17th pin of digital potentiometer 49, the positive input terminal of operational amplifier U3 is connected with the 1st pin of digital potentiometer 49, The negative input terminal of the operational amplifier U3 is connected with the 7th pin of the digital potentiometer 49, the output terminal of the operational amplifier U3 is connected with the 7th pin of the digital potentiometer 49, and the positive input terminal of the operational amplifier U4 is connected with the digital potentiometer 49. The 19th pin is connected, and the negative input terminal of operational amplifier U4 is connected with the 11th pin of digital potentiometer 49, and the output end of operational amplifier U4 is connected with the 11th pin of digital potentiometer 49; Described in the feedback processor 42 The 61st pin and the 62nd pin of the photoelectric CPU44 are connected with the 9th pin and the 14th pin of the digital potentiometer 49 respectively, and the reference voltage source 45 is a built-in voltage source in the photoelectric CPU44, which is used to simulate in the photoelectric CPU44 Reference voltage signal is provided during digital conversion, operational amplifier U6 and resistance R3, R4, Rf form photoelectric amplifier 43 jointly, the output of photoelectric amplifier 43 is connected to the 18th pin of photoelectric CPU44; The terminal P51 is connected with the output terminal of the photoelectric converter, the operational amplifier U51, the capacitor C51, the resistor R51 and the resistor R52 form a DC blocking amplifier 46, one end of the capacitor C51 is connected with the input terminal P51, the operational amplifier U52 is connected with the resistor R53, the resistor R54, the resistor R55 constitutes the photoelectric subtractor 47, the input end of the photoelectric subtractor 47, namely the other end of the resistor R53 and the resistor R54, is connected with the output terminal of the DC blocking amplifier 46 and the input terminal P51 of the AC-DC separator 41 respectively, and the output terminal P52 is connected with the feedback processing The input terminal P5 of the device 42 is connected, and the output terminal P53 is the output terminal of the optical current transformer.

The circuit of above-mentioned AC-DC separator 41, feedback processor 42, and controllable current source 41 is made into a circuit board, and the connection relationship between the three is: the terminal P52 in Fig. 5 is connected with the terminal P5 in Fig. The terminal P3 in FIG. 4 is connected to the terminal P1 in FIG. 3 , and the terminal P4 in FIG. 4 is connected to the terminal P2 in FIG. 3 .

The circuit board is installed in a case, and there are two power terminals on the case, the power terminals are connected with the power supply in the case (not shown in the accompanying drawings), and the output of the power supply is for the AC-DC splitter 41 and the feedback processor 42. The direct current used by the controllable current source 41. There are also two optical fiber flanges on the chassis, which are respectively connected to the light source 29 and the photoelectric converter 27, and are respectively connected to the input optical fiber 8 and the output optical fiber 11 of the optical current transformer during operation. There is also an output terminal on the chassis, which is connected with the output terminal P53 of the DC-blocking amplifier 46 . When working, it can be connected to a meter or a protection device, and the output is an AC voltage signal UAC.

Specific embodiment two: optical current transformer with solenoid type, see Fig. 1, Fig. 6, Fig. 7, Fig. 8.

Fig. 1 is a schematic diagram of a solenoid-type optical current transformer with a single optical path, an optical sensor head 2, that is, a straight strip of magneto-optical material, one end of which is connected to a polarizer 7, an input self-focusing lens 6 and an input optical fiber in sequence 8, the other end of which is sequentially connected to a polarizer 9, an output self-focusing lens 10 and an output optical fiber 11, and the above-mentioned components are arranged along a straight line. The centerlines of the components arranged along a straight line are on the same straight line, and the connection order of the above-mentioned components along the light is input optical fiber 8, input self-focusing lens 6, optical sensor head 2, analyzer 9, output self-focusing lens 10 and The output optical fiber 11 is named as the basic optical path for convenience of description.

The basic optical path is installed and sealed in the metal shell 12, as shown in Figure 6, the metal shell 12 is cylindrical, and the inside is a through hole, and the aperture is the same as the cylindrical sensor head 2, polarizer 7, and analyzer 9 The outer diameter of the round hole matches the outer diameter of the round hole. There is a section of thread near both ends (not shown in the figure), and the outer ends of the two sections of thread each have a section of conical surface. The central circular hole and the conical surface have the same centerline, and there are two The conical end cover 52 has a conical surface matching the metal shell 12 on the outside, and the middle part of the end cover 52 is a tapered hole with the same center line as the external conical surface. The shape of the device 9 matches; the sensor head 2 is installed in the middle of the inner hole, and a circular elastic washer 50 is placed on each side, and the outer edge of the elastic washer 50 is respectively loaded into the polarizer 7 and the polarizer 9, both The polarization direction of the metal shell is relatively rotated by 40 to 50 degrees, and the outer parts on both sides are respectively fixed by the fixing ring 51 with external thread. Adhesive bonding, the input self-focusing lens 6 and the output self-focusing lens 10 of a conical shape are respectively loaded into the tapered holes of the two end caps 52, and the input self-focusing lens 6 and the output self-focusing lens 10 extend out of the end cap 52 For the thin end, the tapered surface is bonded with quick-drying glue, the outermost end of the tapered hole of the metal shell is sealed with a sealant, and the outermost end protrudes from the input optical fiber 8 and the output optical fiber 11 respectively. The circular holes of the elastic washer 50 and the fixing ring 51 are large enough to ensure the smooth flow of the light path. The cone angles of the above two conical surfaces are relatively small.

The conical surface connected between the metal shell 12 and the end cap 52 may not be bonded, but threaded, specifically a 60-degree sealing tapered pipe thread.

The metal shell 12 can also adopt another method: the metal shell 12 is cylindrical, and the inside is a through hole, and the aperture matches the outer diameter of the cylindrical sensor head 2, polarizer 7, and analyzer 9 , each end of the round hole has a section of screw thread, and each end section of the metal shell 12 has at least three screw holes uniformly distributed along the circumferential direction in the same cross section and radiating outward from the center of the metal shell, and there are adjusting fixing screws in the screw holes 32. The fixing screw sinks into the screw hole, and there are two end caps 52. The end caps are cylinders whose outer diameter is slightly smaller than the inner diameter of the end of the metal shell 12, and whose center is the input self-focusing lens 6 and the output of the cylinder. A round hole with a matching outer diameter of the self-focusing lens 10; the sensor head 2 is installed in the middle of the inner hole, and a circular elastic washer 50 is respectively placed on both sides, and the outer edge of the elastic washer 50 is respectively loaded into the polarizer 7 and the analyzer. 9, the polarization directions of the two are relatively rotated by 40 degrees to 50 degrees, and the outer parts of both sides are respectively fixed by fixing rings 51 with external threads, and the input self-focusing lens 6 and the output self-focusing lens 10 are respectively installed in the end caps In the center hole of 52, use quick-drying glue to bond, and end cap 52 is respectively packed in the two ends circular holes of metal shell 12, is fixed with adjusting fixing screw 32, and the outermost end of circular hole is sealed with sealant, and finally The outer end protrudes from the input optical fiber 8 and the output optical fiber 11, and when the end cap 52 is short, three adjustment screws can be used. The adjusting fixing screw 32 can adopt a standard part, a slotted flat end set screw, a slotted conical end set screw or a hexagon socket flat end set screw.

The metal shell 12 of the above two structures can also be a cylinder with an opening at one end and a bottom at the other end. The end cap 52 is still reserved at the opening end, and a conical hole or a circular hole is opened at the center of the bottom of the cylinder at the other end, and the cones are respectively loaded. Cylindrical or cylindrical self-focusing lenses. When assembling, the components are sequentially loaded from the open end, fixed with the fixing ring 51, and then the end cover 52 is assembled.

The metal shell 12 can also be a square shell with an upper cover and an end cover at both ends. The shell is grooved, and its inner and lower part is a 90-degree through V-shaped groove. There is a vertical groove near one end. Square groove, the width of the square groove matches the square analyzer. There is a central hole in the middle of the end cover, which matches the outer diameters of the cylindrical input self-focusing lens and output self-focusing lens, and the upper cover and the end cover can be fixed on the housing by screws. When assembling, place the analyzer in a vertical square groove, put the sensor head in the V-shaped groove close to the analyzer, and put the square polarizer in the V-shaped groove close to the sensor head. At the other end, the bottoms of the above components are glued in the V-shaped groove and the square groove. The input self-focusing lens and the output self-focusing lens are placed in the center hole of the end cover, and the sides are glued in the center hole of the end cover. Fix the end cover to the end of the housing with screws, align the input self-focusing lens and the output self-focusing lens by fine-tuning the relative position of the end cover and the housing, and add an elastic cushion to the upper part of each component to fix the upper cover on the casing.

The above-mentioned metal shell (including the end cover and the upper cover) is made of copper and its alloys or aluminum and its aluminum alloys.

The end face of the optical sensor head is a plane perpendicular to the length direction. The polarizer, analyzer, and self-focusing lens are all in contact with each other. If they are arranged along a straight line, the light is normal incident on the interface and the light passing through is strong. The cross-section of the optical sensor head of the magneto-optic material is square, circular, rectangular, rhombus, ellipse or regular polygon. Magneto-optical materials can use magneto-optic crystals including garnet single crystal and spinel crystal, magneto-optic glass can also be used, each type can use various specific models, magneto-optic glass can use ZF series; garnet single crystal can be used Yttrium iron garnet single crystal series; spinel crystals can be CdCr ₂ S ₄ , CoCr ₂ S ₄ and so on. This example uses ZF-7 magneto-optical glass.

The solenoid 1-1 through which the measured current passes can, for example, be wound by a bus bar with a rectangular or circular or square or polygonal section, and its material can be copper, aluminum or steel, and its pitch is as small as possible, that is, the bus bar of the solenoid The arrangement is as dense as possible, and can be one layer, or two or more layers connected in parallel. In this example, a round copper wire is used to wind a layer. The two ends of the solenoid are ground flat and respectively welded to a copper flat flange 15, and the inner diameter of the flat flange 15 is equal to the outer diameter of the solenoid. Use cylindrical insulating object 3 to fix the basic light path including optical sensing head 2 in the solenoid 1-1, the material of insulating object can be epoxy resin, unsaturated resin, rubber or nylon, this example adopts nylon, The insulating object 3 is a cylinder matched with the inner cavity of the ring conductor, and there are through holes 4 parallel to the axis and at the same distance from the axis as the number of sensor heads, and there is a longitudinal groove 5 on the side of the cylindrical insulating object. The end face of the cylindrical insulating object starts from each through hole 4 to the longitudinal groove 5, and the metal shell with the basic optical path inside is respectively installed in the through hole 4, and the optical fiber is guided from the end groove 13 to the longitudinal groove 5, and outwards from one end. Leading out: using the elasticity of nylon, it can be well assembled into the solenoid, and keep the optical sensor head, especially the strip-shaped magneto-optical material, parallel to the axis of the solenoid. The length of the strip-shaped optical sensing head is much smaller than the length of the solenoid, located in the middle of the solenoid along the length direction, and completely located in the area of parallel magnetic force lines in the solenoid.

In order to prevent vibration and increase elasticity, an epoxy resin cylinder 14 can also be placed outside the insulating object 3 of nylon, and the gap between the cylinder and the nylon insulating block is filled with silicon rubber, and the epoxy resin cylinder is assembled in the solenoid, which can Tighten symmetrically with paper strips.

The length of the cylindrical insulating object is equal to the length of the outer edge of the flat flange 15 welded by the solenoid, and the flat flange is provided with a structural groove 16 corresponding to the slotting of the insulating object 3 to lead out the optical fiber. The outside of the flat flange is connected with a confluence plate 18 with a raised conductive rod 26 (that is, a flange with a protruding rod). The confluence plate is connected, and the other 4 holes are used for reinforcement, that is, the epoxy resin rod 17 whose length is equal to the distance between the inner surfaces of the two flat flanges is installed between the two flat flanges 15. There are screw holes on the two ends of the rod, and the screw holes Connect the rod to the flange.

The assembled optical current transformer has a base box 22 below, an insulator 21 in the middle, and a housing 19 on the top. The three can be connected by flanges (not shown in the figure), and the center of the insulator 21 has a longitudinal optical fiber bundle. Both ends extend beyond the two flanges of the insulator. The upper part of the housing is a horizontal cylinder. There are holes in the center of the two end covers for the conductive rod 26 of the confluence plate to pass through. At least one of the two end covers is a movable cover, which is fixed on the cylinder with screws so that the spiral tube etc. There is also a gland 20 outside the two end covers. The aperture of the gland at one end is greater than the diameter of the conductive rod 26 of the busbar, and an insulating sleeve 25 is housed. The inner diameter of the insulating sleeve cooperates with the conductive rod 26 of the busbar. The diameter is thick and thin, and the thin section is in the hole of the gland, and the thick section is in the hole of the end cover and the housing. The insulating sleeve insulates the manifold at this end from the housing, and limits the axial movement of the manifold. The other end is not equipped with an insulating sleeve, the gland hole is matched with the conductive rod, and the bus plate at this end is in close contact with the shell, so that the shell and the line under test are at the same potential. The lower part of the housing is a small section of vertical pipe, the lower end of which is a flange. The optical fiber drawn from the structure groove 16 is respectively connected with the optical fiber extending from the upper end of the insulator 21 at the bottom of the housing, and the optical fiber extending from the lower end of the insulator is connected with the optical fiber flange of the photoelectric information processor 23. The content of the photoelectric information processor 23 is completely related to the specific implementation. The method is the same as the first method and will not be repeated. The photoelectric information processor 23 can be placed in the base box 22, and can also be placed on the user's instrument panel. When in application, the optical current transformer is installed on the frame, and the corner hole on the base box is fixed on the platform of the frame with bolts; the optical current transformer is connected in series to the measured line through the conductive rod of the confluence plate.

Specific embodiment three: Ω hard bus type optical current transformer with two basic optical paths, see Fig. 10 , Fig. 11 and Fig. 12 .

The conductor for the measured current to pass is an Ω-shaped bus bar 1-2 made of a wide and flat hard bus bar. The shape of the object is a cylinder 30 on the outside, and a flat plate 31 passing through the busbar is fixed inside the cylinder 30 . The outer diameter of the cylinder 30 is equal to the inner diameter of the cylinder of the Ω-shaped busbar 1-2, and two basic optical paths are arranged symmetrically on one side of the plate 31 (or on both sides respectively). Each basic optical path is an input optical fiber 8, an input self-focusing lens 6, a polarizer 7, an optical sensor head 2, a polarizer 9, an output self-focusing lens 10, and an output optical fiber 11 arranged along a straight line. The basic optical path is installed and Sealed in the metal shell 12, the details are the same as the second embodiment, and will not be repeated. Metal shell 12 is fixed on the flat plate 31 with clamping band 24 during installation. When installing and fixing, it is necessary to ensure that the straight optical sensing heads are parallel to the axis of the cylinder 30, and the distance from the center line of the two optical sensing heads to the axis is equal, that is, the two optical sensing heads are parallel to Ω The axis of the generatrix and the distance to the axis are equal, so as to ensure that the two optical sensor heads are parallel to the magnetic field lines, and the magnetic field strengths at the two places are equal. The material of the two optical sensing heads is ZF-7 magneto-optical glass.

In the straight section of the opening of the Ω-shaped busbar 1-2, an insulating block 33 is arranged inside, and a clamping plate 34 is respectively arranged on the outside. A pressing plate 35 of insulating material is respectively arranged at both ends of the Ω-shaped bus 1-2, and one side of the pressing plate has a groove or a boss matching the Ω-shaped, and is oppositely embedded in the two ends of the Ω-shaped bus. The two pressing plates have corresponding holes to clamp the two pressing plates with bolts. The difference between the length of the insulating object 3 and the axial length of the Ω-shaped busbar is twice the depth or height of the groove or boss, and the pressing plate not only fixes the shape of the Ω-shaped busbar but also axially fixes the insulating object 3. There are square holes at the corresponding splints of the two clamping plates for the ends of the two clamping plates and the bolts to extend out of the clamping plates.

The above-mentioned Ω-shaped bus bar installed together with the basic optical path is installed in the shell cover 38, and the support plate 36 is below the shell cover 38, and the two are fixed with bolts. The support plate 36 is a square flat plate, and there is a circular tube in the lower part of the plate, and the lower part of the tube is a flange (not shown in the figure). Insulation pad 37, the straight section of the Ω-shaped bus bar is placed on two insulating pads, and the shell cover 38 is buckled on it. The opening of the shell cover has a flanging and is fixed on the support plate with bolts. The segment has an insulating sheet 39 above the insulating pad 37 to insulate the Ω-shaped bus bar on this side from the shell, and there is no insulating sheet above the straight segment on the other side, so that the shell is at the same potential as the conductor flowing the measured current. The straight section of the Ω-shaped bus bar extends out of the shell to both sides. The input optical fibers and output optical fibers of each optical path fixed in the insulating object 3 are assembled into optical fiber bundles, drawn from a hole of a pressure plate 35, and stretched to the lower part of the housing through the circular tube below the support plate 36.

In application, a base box 22 is installed on the frame, on which is an insulator 21 with a through-fiber bundle fixed by a flange, and the shell is fixed with a flange on the insulator, and the straight section of the Ω-shaped bus bar 1-2 exits in the shell connected in series to the high voltage line under test. Before the flanges at both ends of the insulator are connected, the optical fibers at the upper end are respectively connected with the optical fibers protruding from the lower part of the housing with optical fiber flanges, and the optical fibers at the lower end of the insulator are respectively connected with the photoelectric information processor 23 in the base box with optical fiber flanges , the specific structure of the photoelectric information processor 23 is the same as that of the first embodiment, and will not be repeated here.

The photoelectric information processor 23 can also not be contained in the base box when the scene needs, but the extension optical fiber is contained in the control room.

When the current passes through, the ring conductor forming a magnetic field parallel to the magnetic force line in its inner cavity can also be a flexible Ω-shaped bus bar wound by a multi-layer thin busbar, whether the rigid or flexible busbar loops, it can also be U-shaped , square zigzag, triangular zigzag, and polygonal zigzag.

When working, one of the two optical paths is running, and the other is used as a backup; the two can also be used at the same time, and the output results are averaged, thereby improving the measurement accuracy of the optical current transformer.

The shape of the insulating object 3 that fixes the basic optical path and the outer metal shell in the inner cavity of the ring conductor can also be the following: 1. The outside of the insulating object 3 is a cylinder, and the inside is a cross-shaped plate;

2. The main body of the insulating object 3 is a flat plate, and the two ends of the flat plate are short cylinders;

3. The main body of the insulating object 3 is a flat plate, and the two sides of the plate are long arc-shaped plates, and its cross-section is I-shaped;

4. The middle part of the insulating object is a flat plate, and there is a circular plate perpendicular to the flat plate at both ends;

5. The insulating object is three plates arranged in a Y shape;

6. The insulating object is formed by pouring in the ring conductor cavity;

The metal shell 12 is fixed on the flat plate with a clamping band; the outer diameters of the cylinders, cylinders, arc-shaped plates, and circular plates in the above-mentioned various forms are all matched with the inner cavity diameter of the ring conductor; the material of the insulating object is Any of epoxy resin, unsaturated resin, rubber, and nylon.

The basic principle of the optical current transformer is briefly described below:

The input light intensity to the basic optical path is J _i , and the magnetic field generated by the current Under the action of , the polarization plane of the linearly polarized light after passing through the magneto-optical glass is deflected by the Faraday rotation angle The light intensity after passing through the analyzer is J _o1 :

In the formula, δ is the linear birefringence of Faraday magneto-optic glass. The influence of temperature, stress and other factors on the optical current transformer is reflected in the linear birefringence δ of Faraday magneto-optic glass. δ changes with temperature, stress and other factors and change;

——Faraday rotation angle, reflecting the measured AC current i.

When the output light of the basic optical path is output to the photoelectric converter, the voltage signal U _O output by the photoelectric converter is:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; DC</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; AC</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; J</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; J</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; sin</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; J</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&delta;</span>}}{\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ]</span>$

Wherein, K is the voltage light intensity response ratio of photoelectric converter, is a constant; V is the Verdet constant of magneto-optical glass; _i is the input light intensity.

When the temperature does not change, the linear birefringence δ is a constant, and the voltage signal U _O output by the photoelectric converter includes a DC voltage signal U _DC and an AC voltage signal U _AC , and the AC voltage signal U _AC is proportional to the measured AC current i, the ratio Coefficients are constants.

When the temperature changes, the linear birefringence δ is a variable, and the voltage signal U _O output by the photoelectric converter includes a slowly changing DC voltage signal U _DC and an AC voltage signal U _AC , and the AC voltage signal U _AC is proportional to the measured AC current i The coefficient K _w is the proportional relationship of variables, that is, i=K _w U _AC , and the proportional coefficient K _w of this change cannot be obtained in advance due to the randomness of temperature changes. Therefore, the practical application of optical current mutual inductance in power systems When the transformer is used, the ambient temperature is changing. If the measured current value is output directly according to the AC voltage signal U _AC and a fixed proportional coefficient, it is obviously inaccurate. At this time, the measurement accuracy of the optical current transformer is not high.

For this reason, the present invention provides a kind of negative feedback optical current transformer, and its basic theoretical method is: the linear birefringence δ that changes with temperature is included in both the AC voltage signal U _AC and the DC voltage signal U _DC , because the temperature changes very slowly, so in a very short time, the voltage signal U _O output by the photoelectric converter can be separated into AC voltage signal U _AC and DC voltage signal U _DC , and the DC voltage signal U _DC contains linear Birefringence δ, the change of linear birefringence δ can be known through the measured DC voltage signal U _DC , so that the proportional coefficient K _w that changes with temperature changes can be obtained in real time, and then by adjusting the input light intensity J _i of the basic optical path, so that The proportionality coefficient _Kw remains unchanged when the temperature changes, thereby eliminating the influence of temperature on the optical current transformer, thereby improving the measurement accuracy of the optical current transformer.

Claims (6)

1. An optical current transformer, comprising an insulating support (21), a conductor, an optical sensing head, a polarizer, a polarizer, and an optical lens for the passage of the measured current; said conductor for the passage of the measured current It is a ring conductor that forms a magnetic field parallel to the magnetic force lines in its inner cavity when the current passes through; the said optical sensor head (2) is a straight magneto-optical material, and its length is much smaller than the length of the ring conductor axis direction. The two end faces of the head are planes perpendicular to the length direction; the optical sensor head together with the related elements constituting the basic optical path are fixed in the cavity of the ring conductor with an insulating object (3), and the optical sensor head is parallel to the ring conductor axis, and is located in the middle of the cavity along the axial direction, in the region of parallel magnetic lines of force; the input optical fiber (8) and output optical fiber (11) pass through the middle hole of the insulating support (21) to the low-voltage side; its features are: There is at least one basic optical path in the inner cavity of the ring conductor for the current to be measured. The optical sensing head and its related optical elements are arranged along a straight line to form the basic optical path. These elements are arranged in the order of light passing: input optical fiber (8) , input self-focusing lens (6), polarizer (7), optical sensing head (2), analyzer (9), output self-focusing lens (10), output optical fiber (11); analyzer (9 ) relative to the polarization plane of the polarizer (7) rotates 40 to 50 degrees around the axis of the sensor head, and the above-mentioned basic optical path is installed and sealed in a metal shell (12) with good thermal conductivity; device (23), the photoelectric information processor (23) includes a photoelectric converter (27), an AC-DC separator (41), a feedback processor (42), a controllable current source (40) and a light source (29), and the information is according to The above sequence transfers, the AC-DC separator (41) outputs two kinds of electrical signals, AC and DC, wherein the AC signal is the output signal of the optical current transformer; its DC signal is input to the feedback processor (42), and the feedback processor (42) The output of is connected to the input of a controllable current source (40). 2. The optical current transformer according to claim 1, characterized in that: the AC-DC separator (41) includes a DC blocking amplifier (46) and a photoelectric subtractor (47), and the DC blocking amplifier (46) receives the photoelectric The voltage signal sent by the converter (27) is output outwards after being amplified by the AC voltage through DC blocking, that is, the output of the optical current transformer, and is output to the photoelectric subtractor (47) inwardly at the same time, and the photoelectric subtractor ( 47) also receive the voltage signal that transmits from photoelectric converter (27), carry out subtraction operation to both, obtain DC voltage signal; Described feedback processor (42) comprises photoelectric amplifier (43), photoelectric CPU (44) and Reference voltage source (45), reference voltage source (45) is connected on the photoelectric CPU (44), and reference voltage source (45) is the built-in voltage source of photoelectric CPU (44), and photoelectric amplifier (43) receives from photoelectric subtractor ( 47) the DC voltage signal output, the voltage signal is amplified, and output to the photoelectric CPU (44), the photoelectric CPU (44) performs analysis and calculation according to the DC voltage signal, and outputs a digital signal instruction; the controllable current source ( 40) comprising a light source (29), an adjustable reference voltage source (48) and a digital potentiometer (49), the adjustable reference voltage source (48) supplies power to the light source (29), and the digital potentiometer (49) receives the photoelectric CPU (44 ) output digital signal command is converted into a voltage signal, output to the adjustable reference voltage source (48), the adjustable reference voltage source (48) changes the output voltage according to the voltage signal sent by the digital potentiometer (49), and then Changing the current intensity input to the light source (29) also changes the light intensity emitted by the light source (29). 3. According to the described optical current transformer of claim 1, it is characterized in that: the metal shell (12) is cylindrical, and the inside is a through hole, and the aperture is the same as that of the cylindrical sensing head (2), starting The outer diameters of the polarizer (7) and the polarizer (9) match each other. There is a section of thread near both ends of the circular hole, and a section of conical surface at the outer end of the two sections of thread. The central circular hole and the conical surface have the same center line. , there are also two conical end caps (52), the outside of which is a conical surface matched with the metal shell (12), and the middle part of the end cap (52) is a tapered hole with the same center line as the external conical surface, The tapered holes match the shapes of the polarizer (7) and the analyzer (9); The sensor head (2) is installed in the middle of the inner hole, and a circular elastic washer (50) is placed on each side, and the outer edge of the elastic washer (50) is respectively installed into the polarizer (7) and the polarizer (9) , the polarization directions of the two are relatively rotated by 40° to 50°, and the outer parts on both sides are respectively fixed by fixing rings (51) with external threads, and the end caps (52) are respectively installed into the conical In-plane, the conical surface is bonded with quick-drying glue, and the conical input self-focusing lens (6) and output self-focusing lens (10) are respectively loaded into the tapered holes of the two end caps (52). The focusing lens (6) and the output self-focusing lens (10) stretch out from the thin end of the end cap (52). Out of the input fiber (8) and output fiber (11). 4. According to the described optical current transformer of claim 1, it is characterized in that: the metal shell (12) is cylindrical, and the inside is a through hole, and the aperture is the same as that of the cylindrical sensing head (2), starting The outer diameters of the polarizer (7) and the polarizer (9) match each other, there is a section of thread at both ends of the round hole, and there are at least three through holes uniformly distributed along the circumferential direction in the same cross section of the metal shell (12). There are screw holes radiating outward from the center of the metal shell. There are adjusting fixing screws (32) sunk into the screw holes in the screw holes, and two end caps (52). The inner diameter of the portion is slightly smaller cylinder, and its center is a circular hole matched with the cylindrical input self-focusing lens (6) and the output self-focusing lens (10) outer diameter; The sensor head (2) is installed in the middle of the inner hole, and a circular elastic washer (50) is placed on each side, and the outer edge of the elastic washer (50) is respectively installed into the polarizer (7) and the polarizer (9) , the polarization directions of the two are relatively rotated by 40 to 50 degrees, and the outer parts of both sides are respectively fixed by fixing rings (51) with external threads, and the input self-focusing lens (6) and the output self-focusing lens (10) are respectively Put it into the center hole of the end cover (52), stick it with quick-drying glue, put the end cover (52) into the round holes at both ends of the metal shell (12), and fix it with the adjusting fixing screw (32). The outermost end of the circular hole is sealed with a sealant, and the outermost end protrudes from the input optical fiber (8) and the output optical fiber (11). 5. The optical current transformer according to claim 1, characterized in that: said ring conductor is a curved surface made of a solenoid (1-1) or a wide flat busbar, which is divided into cylindrical Ω-shaped busbars (1-2); the two ends of said solenoid (1-1) are ground flat and respectively welded with a flat flange (15), and a part of the holes of the two flat flanges are used for fixing the reinforcement rod (17), and the reinforcement The length of the rod is equal to the inner distance of the two flat flanges, the material is epoxy resin, screw holes are arranged at both ends, and the other part of the flat flange (15) is connected with a confluence plate (18) with a raised conductive rod (26); The wire tube is connected in parallel in one or more layers. The material of the solenoid is any one of copper, aluminum or steel. The cross-section of the wire of the solenoid is any of circular, rectangular, square, and oval. The said Ω-shaped busbar (1-2) is a rigid Ω-shaped busbar made by bending a hard busbar or a flexible Ω-shaped busbar formed by winding a cylindrical insulating object with multi-layer sheets, and the cylindrical part of the rigid Ω-shaped busbar It is semi-cylindrical to close to the cylinder, and the opening is insulated and fixed. The cylindrical part of the flexible Ω-shaped busbar has insulating clips; The slot or boss where the Ω-shaped busbar matches, the bolt clamps the two pressure plates and the insulating object in the Ω-shaped busbar is fixed between the two pressure plates. The material of the Ω-shaped busbar is any one of copper, aluminum and steel. 6. The optical current transformer according to claim 1, characterized in that: the shape of the insulating object that fixes the optical sensor head and its related elements forming the basic optical path in the said annular conductor cavity is as follows Any of A, B, C, D, F, G, H: A. The insulating object (3) is a cylinder that matches the inner cavity of the ring conductor, and there are through holes (4) in the same number as the sensor heads that are parallel to the axis and have the same distance from the axis. On the side of the cylindrical insulating object, there are A longitudinal groove (5), opening grooves (13) respectively from each through hole (4) to the longitudinal groove (5) on the end face of the cylindrical insulating object, and the metal shell (12) of the basic optical path is loaded into the through hole (4) respectively ), the optical fiber is guided from the end slot (13) to the longitudinal slot (5), and is drawn out from one end; B, the outside of the insulating object (3) is a cylinder (30), and its inside is at least one longitudinal flat plate (31); C, the outside of the insulating object (3) is a cylinder, and the inside is a cross-shaped plate; D, the main body of the insulating object (3) is a flat plate, and the two ends of the flat plate are cylinders of short sections; F. The middle part of the insulating object is a flat plate, and there is a circular plate perpendicular to the flat plate at each end; G. The insulating object is three plates arranged in a Y shape; H. The insulating object is formed by pouring in the ring conductor cavity; When B, C, D, F or G mode is used, the basic optical path is enclosed in the metal shell and fixed on the plate; The outer diameters of cylinders, cylinders, and circular plates in the above-mentioned various shapes are matched with the inner diameter of the ring conductor; The material of the insulating object is any one of epoxy resin, unsaturated resin, rubber and nylon.