CN212321706U - Passive electronic current transformer - Google Patents
Passive electronic current transformer Download PDFInfo
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- CN212321706U CN212321706U CN202020973269.9U CN202020973269U CN212321706U CN 212321706 U CN212321706 U CN 212321706U CN 202020973269 U CN202020973269 U CN 202020973269U CN 212321706 U CN212321706 U CN 212321706U
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Abstract
The utility model relates to an electric power system measures the field, concretely relates to passive electronic current transformer's design. The method comprises the following steps: the optical fiber interference detector comprises a light source closed-loop feedback control loop, an integrated optical device, an optical fiber loop, a double-closed-loop control loop and a temperature compensation module, wherein the light source closed-loop feedback control loop outputs optical signals to the integrated optical element, the optical signals are transmitted to the optical fiber loop through a delay line and an 1/4 wave plate to generate interference, the interference signals are returned to a second detector, the second detector is connected with the double-closed-loop control loop and feeds the interference signals back to the integrated optical device through the double-closed-loop control loop, and the temperature compensation module is connected with the second detector. The utility model has the characteristics of insulation system is simple reliable, small, light in weight, linearity are good, the interference killing feature is strong.
Description
Technical Field
The utility model relates to an electric power system measures technical field, concretely relates to passive electronic current transformer.
Background
In a new generation of intelligent transformer substation, a transformer is an important device for monitoring the operation state of the transformer, and measurement, monitoring and protection control in the transformer substation depends on the transformer to obtain information such as current, voltage and the like required by measurement, metering and protection. With the improvement of voltage grade, the traditional electromagnetic mutual inductor has the defects of weak electrical insulation, heavy volume, small dynamic range, iron core saturation, ferromagnetic resonance overvoltage and the like. Because the electromagnetic current transformer is difficult to maintain certain precision and linearity in a large range, at least two or more groups of independent transformers are needed for measurement and protection. The output signals of the electromagnetic mutual inductor are transmitted in an analog quantity mode, different signals need to be transmitted by different signal cables, the number of cables is large, remote transmission is limited, and the electromagnetic mutual inductor is easy to be interfered by electromagnetic waves. Particularly, the iron core saturation phenomenon of the current transformer brings a lot of difficulties for relay protection to correctly identify faults.
Therefore, a new transformer is needed to meet the requirement of the new generation of intelligent transformer substation.
Disclosure of Invention
An object of the utility model is to solve the problem that traditional electromagnetic type current transformer exists, provide a passive electronic current transformer to reach higher security and reliability, realize big dynamic range accurate measurement.
The utility model provides a passive electronic current transformer, which comprises a light source closed loop feedback control loop, an integrated optical device, an optical fiber loop, a double closed loop control loop and a temperature compensation module;
the dual closed-loop control loop includes: the second detector, a preamplifier, an A/D converter, a main demodulator, an auxiliary demodulator, a main integrator, an auxiliary integrator, a modulation square wave generator, a step wave generator, a main D/A converter, an auxiliary D/A converter, an operational amplifier and a DR converter; the second detector is connected with an A/D converter through a preamplifier, the A/D converter is respectively connected with a main demodulator and an auxiliary demodulator, the main demodulator is connected with a main integrator, the auxiliary demodulator is connected with an auxiliary integrator, the auxiliary integrator is respectively connected with an auxiliary D/A converter and a DR converter, the main integrator is connected with a step wave generator, and the modulation square wave generator is respectively connected with the main integrator and the auxiliary integrator;
the light source closed-loop feedback control circuit outputs optical signals to the integrated optical device, the optical signals are transmitted to the optical fiber ring through the delay line and the 1/4 wave plates in sequence to generate interference, the interference signals are returned to the second detector, the second detector is connected with the double closed-loop control circuit and feeds the interference signals back to the integrated optical device through the double closed-loop control circuit, and the temperature compensation module is connected with the second detector.
Further, the integrated optical device includes: the device comprises a first polarization-maintaining optical fiber coupler, a Y waveguide chip and a second polarization-maintaining optical fiber coupler; the first polarization maintaining fiber coupler is connected with a light source closed-loop feedback control circuit, optical signals are transmitted to the Y waveguide chip through the first polarization maintaining fiber coupler, 90-degree counter-axis is realized on one arm between the second polarization maintaining fiber coupler and the Y waveguide chip, and light waves of two arms of the Y waveguide chip are transmitted to the delay coil through the second polarization maintaining fiber coupler.
Furthermore, the integrated optical device adopts a Y waveguide reflection optical path, a mode matching optical fiber is selected as a polarization maintaining optical fiber, and an HB spike optical fiber is adopted as an optical fiber ring, so that the circular birefringence of the optical fiber is improved, and the increase of the linear birefringence is inhibited.
Furthermore, the optical fiber ring comprises an annular framework and optical fibers wound outside the annular framework, flexible materials used for supporting the optical fibers are evenly coated on the periphery of the annular framework, the optical fibers can be immersed in the flexible materials, and the optical fibers are not attached to the annular framework.
Further, the light source closed-loop feedback control loop comprises an SLD light source, a Lyot depolarizer, a first coupler, a first detector, a processing circuit and a driving circuit, wherein light signals emitted by the SLD light source are transmitted to the first coupler through the Lyot depolarizer, the first coupler outputs signals transmitted to the first detector while outputting the light source, and the signals are fed back to the SLD light source through the processing circuit and the driving circuit to automatically adjust the central wavelength of the SLD light source.
The utility model has the advantages of it is following:
(1) the passive electronic current transformer has a relatively high measurement range and precision, and the problem of magnetic saturation of the traditional electromagnetic transformer is thoroughly solved by introducing a double closed-loop control circuit;
(2) the flexible material for supporting the optical fiber is uniformly coated on the periphery of the annular framework for winding the optical fiber, the optical fiber can be immersed in the flexible material, and the optical fiber is not attached to the annular framework. By adopting the process, the passive electronic current transformer can not be influenced by vibration, and the temperature characteristic is greatly improved;
(3) by introducing a light source closed-loop feedback control loop, the central wavelength of the SLD light source is automatically adjusted, the temperature drift of the central wavelength of the SLD light source is inhibited, and meanwhile, a temperature compensation module is added, so that the temperature characteristic of the passive electronic current transformer is greatly improved.
Drawings
FIG. 1 is a functional block diagram of a passive electronic current transformer according to the present embodiment;
FIG. 2 is a schematic diagram of the integrated optical device of the present embodiment;
FIG. 3 is a schematic diagram of a symmetrical "four-state" square wave modulation provided by the present embodiment;
fig. 4 is a schematic diagram of a flexible support winding technique for the sensing optical fiber provided in this embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, in the present embodiment, a passive electronic current transformer includes a light source closed-loop feedback control loop, an integrated optical device, a fiber loop, a double closed-loop control loop, and a temperature compensation module. The dual closed-loop control loop includes: the second detector, a preamplifier, an A/D converter, a main demodulator, an auxiliary demodulator, a main integrator, an auxiliary integrator, a modulation square wave generator, a step wave generator, a main D/A converter, an auxiliary D/A converter, an operational amplifier and a DR converter; the second detector is connected with the A/D converter through the preamplifier, the A/D converter is connected with the main demodulator and the auxiliary demodulator respectively, the main demodulator is connected with the main integrator, the auxiliary demodulator is connected with the auxiliary integrator, the auxiliary integrator is connected with the auxiliary D/A converter and the DR converter respectively, the main integrator is connected with the step wave generator, and the modulation square wave generator is connected with the main integrator and the auxiliary integrator respectively. The light source closed-loop feedback control circuit outputs optical signals to the integrated optical device, the optical signals are transmitted to the optical fiber ring through the delay line and the 1/4 wave plates in sequence to generate interference, the interference signals are returned to the second detector, the second detector is connected with the double closed-loop control circuit and feeds the interference signals back to the integrated optical device through the double closed-loop control circuit, and the temperature compensation module is connected with the second detector.
As shown in fig. 2, in the present embodiment, the integrated optical device includes: the device comprises a first polarization-maintaining optical fiber coupler, a Y waveguide chip and a second polarization-maintaining optical fiber coupler; the first polarization maintaining fiber coupler is connected with a light source closed-loop feedback control circuit, optical signals are transmitted to the Y waveguide chip through the first polarization maintaining fiber coupler, 90-degree counter-axis is realized on one arm between the second polarization maintaining fiber coupler and the Y waveguide chip, and light waves of two arms of the Y waveguide chip are transmitted to the delay coil through the second polarization maintaining fiber coupler.
In this embodiment, the integrated optical device adopts a Y-waveguide reflective optical path, selects a mode-matching optical fiber as a polarization-maintaining optical fiber, and adopts an HB spun optical fiber as an optical fiber ring to improve the circular birefringence of the optical fiber and suppress the increase of the linear birefringence.
In this embodiment, the working process of the passive electronic current transformer is specifically as follows:
the magneto-optical faraday effect based on optical fibers is that polarized light propagating in an optical fiber is rotated by a magnetic field. Angle of rotation
Proportional to the magnetic field strength H, the length L of the fiber loop in the magnetic field:
in the formula, V is the Verdet constant of the optical fiber material, and N is the number of turns of the sensing optical fiber ring. The closed magnetic field generated by the current-carrying conductor satisfies the ampere-loop law, i.e. the current intensity enclosed by the closed magnetic field
Thus:
the Jones matrix of the corresponding sensing fiber loop can also be expressed as:
the Jones matrix for the polarization maintaining fiber is:
in the formula, l is the length of the polarization maintaining fiber, Δ n is the refractive index difference of the fiber, j is an imaginary number unit, and k is an integer.
In forward propagation, the Jones matrix for the 1/4 wave plate is:
in reverse propagation, the Jones matrix for the 1/4 wave plate is:
setting the initial light vector as:
then the light wave passes through the 0 degree arm and returns to the front of the second polarization maintaining fiber coupler
Comprises the following steps:
obtaining by solution:
similarly, the light wave returns to the front of the second polarization maintaining fiber coupler again through the 90-degree arm
Comprises the following steps:
the final interference signal is expressed as:
the current intensity can be obtained by demodulating the phase signal in the above formula, wherein I0Are constants related to light intensity, photoelectric conversion efficiency, loss, and the like.
In this embodiment, a closed-loop demodulation scheme is adopted, and a good effect is achieved on the linearity of the whole measurement range, and a schematic block diagram is shown in fig. 1. The high-speed AD converter is utilized to convert the analog signal of the interference light intensity output by the modulator into digital signals which respectively enter the main demodulator and the auxiliary demodulator, and the demodulated signals enter the main integrator and the auxiliary integrator to complete the control algorithm of digital sampling, demodulation, digital integration and the like. The modulation square wave generator generates a square wave of +/-pi/2, namely a phase offset of +/-pi/2 is introduced to promote the mutual inductor to work at the corner of a cosine response curve to obtain the maximum sensitivity, namely a transfer function is changed into
Wherein, PinIs a constant that, depending on the particular optical path,
is the phase shift induced through the fiber loop.
The output signal of the main integrator forms step waves through a step wave generator, namely, a digital signal of interference light intensity is used as a control signal to control the step wave generator, the step height of the step waves is changed, after the step waves generated by the step wave generator and the modulation square waves generated by the modulation square wave generator are added, the synthesized digital signal is converted into an analog signal through a main DA converter, and the analog signal is applied to a Y waveguide chip in an integrated optical device through operational amplifier to form a first closed loop, so that the phase zero setting is realized. The output signal of the secondary integrator forms a second closed loop through the DR converter and the operational amplifier, and the modulation wave reset is realized. Therefore, an open-loop cosine curve output by the second detector is converted into linear response, the measurement range and the measurement precision of the passive electronic current transformer are greatly improved, and the problem of magnetic saturation of the traditional electromagnetic transformer is thoroughly solved.
As shown in fig. 3, in consideration of the influence of the long-term stability of the transformer on the long-term slow drift of the optical device, in this embodiment, symmetric "four-state" square wave modulation is adopted, the variable quantity of the modulation efficiency is obtained by demodulating 4 symmetric operating points, and then the automatic tracking and feedback correction of the modulation efficiency is realized by controlling the operating points of the main D/a converter and the auxiliary D/a converter, so that the long-term stability of the system is greatly improved.
As shown in fig. 1, in consideration of the influence of the temperature on the central wavelength of the light source, in the present embodiment, a closed-loop feedback control loop for the light source is used to suppress the temperature drift of the central wavelength of the SLD light source. The light source closed-loop feedback control loop comprises an SLD light source, a Lyot depolarizer, a first coupler, a first detector, a processing circuit and a driving circuit, wherein light signals emitted by the SLD light source are transmitted to the first coupler through the Lyot depolarizer, the first coupler outputs the light source and simultaneously transmits signals to the first detector, the light sources are fed back to the SLD light source through the processing circuit and the driving circuit, and the central wavelength of the SLD light source is automatically adjusted. The SLD light source sends out the optical signal and turns into the unpolarized light through Lyot depolarizer, export to the Y waveguide light path through the first coupler, the first detector couples to first coupler, collect the optical signal center wavelength data exported, and form the feedback signal through processing circuit and drive circuit, control SLD light source temperature automatic regulation light source center wavelength.
In the embodiment, the temperature compensation module is added, namely the temperature coefficient of the passive electronic current transformer is calculated by testing the specific difference or angular difference data of the passive electronic current transformer at different temperatures, the test data is fitted into the temperature model of the passive electronic current transformer by using the least square method, and the temperature model is written into the electrical unit software of the passive electronic current transformer, so that the temperature compensation of the passive electronic current transformer is realized. The specific principle is as follows:
the output I (T, I) of the passive electronic current transformer can be expressed as:
I(T,i)＝K(T)f(i)
where T is the ambient temperature, i is the primary current value, K (T) is the temperature coefficient, and can be expressed as:
in the formula, epsilon (T) is a specific difference test result of the passive electronic current transformer at different temperatures.
The temperature coefficient of the passive electronic current transformer can be calculated by testing the specific difference data of the passive electronic current transformer at different temperatures, so that a temperature model of the passive electronic current transformer is established, and then the temperature compensation of the passive electronic current transformer is realized by a software method. Similarly, the method is also suitable for temperature compensation of the angular difference data. In the temperature modeling test process, the accuracy and the temperature data of the transformer are recorded every 10 minutes, and after the test is completed, the test data are fitted into a temperature model of the passive electronic current transformer by using a least square method. And the temperature model is written into the electrical unit software of the passive electronic current transformer, so that the temperature compensation of the passive electronic current transformer can be realized.
In this embodiment, a flexible supporting and winding technology for the sensing optical fiber is designed, as shown in fig. 4. The optical fiber ring comprises an annular framework and optical fibers 3 wound outside the annular framework 1, flexible materials 2 used for supporting the optical fibers 3 are evenly coated on the periphery of the annular framework 1, the optical fibers 3 can be immersed in the flexible materials, and the optical fibers 3 are not attached to the annular framework 1. A layer of flexible material is uniformly coated on the periphery of the winding framework to support the optical fiber, the flexible supporting material is gel or other low-elasticity materials, and the sensing optical fiber is equivalently immersed in the flexible material and is not tightly combined with the winding framework. The electronic current transformer adopting the process can be basically free from the influence of vibration, and meanwhile, the temperature characteristic is greatly improved.
The above description of the present invention does not limit the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the scope of the claims of the present invention.
Claims (5)
1. A passive electronic current transformer is characterized by comprising a light source closed-loop feedback control loop, an integrated optical device, an optical fiber loop, a double closed-loop control loop and a temperature compensation module;
the dual closed-loop control loop includes: the second detector, a preamplifier, an A/D converter, a main demodulator, an auxiliary demodulator, a main integrator, an auxiliary integrator, a modulation square wave generator, a step wave generator, a main D/A converter, an auxiliary D/A converter, an operational amplifier and a DR converter; the second detector is connected with an A/D converter through a preamplifier, the A/D converter is respectively connected with a main demodulator and an auxiliary demodulator, the main demodulator is connected with a main integrator, the auxiliary demodulator is connected with an auxiliary integrator, the auxiliary integrator is respectively connected with an auxiliary D/A converter and a DR converter, the main integrator is connected with a step wave generator, and the modulation square wave generator is respectively connected with the main integrator and the auxiliary integrator;
the light source closed-loop feedback control circuit outputs optical signals to the integrated optical device, the optical signals are transmitted to the optical fiber ring through the delay line and the 1/4 wave plates in sequence to generate interference, the interference signals are returned to the second detector, the second detector is connected with the double closed-loop control circuit and feeds the interference signals back to the integrated optical device through the double closed-loop control circuit, and the temperature compensation module is connected with the second detector.
2. The passive electronic current transformer of claim 1, wherein the integrating optics comprise: the device comprises a first polarization-maintaining optical fiber coupler, a Y waveguide chip and a second polarization-maintaining optical fiber coupler; the first polarization maintaining fiber coupler is connected with a light source closed loop feedback control circuit, optical signals are transmitted into the Y waveguide chip through the first polarization maintaining fiber coupler, 90-degree counter shafts are realized on one arm between the second polarization maintaining fiber coupler and the Y waveguide chip, and light waves of two arms of the Y waveguide chip are transmitted into the delay coil through the second polarization maintaining fiber coupler.
3. The passive electronic current transformer according to claim 1 or 2, wherein the integrated optical device employs a Y-waveguide reflective optical path, a mode-matching optical fiber is selected as the polarization maintaining optical fiber, and an HB spun optical fiber is used as the optical fiber ring.
4. The passive electronic current transformer of claim 3, wherein the optical fiber ring comprises a ring-shaped framework and optical fibers wound outside the ring-shaped framework, and a flexible material for supporting the optical fibers is uniformly coated on the periphery of the ring-shaped framework, the optical fibers can be immersed in the flexible material, and the optical fibers are not attached to the ring-shaped framework.
5. The passive electronic current transformer of claim 1, 2 or 4, wherein the light source closed-loop feedback control loop comprises an SLD light source, a Lyot depolarizer, a first coupler, a first detector, a processing circuit and a driving circuit, the SLD light source emits a light signal, the light signal is transmitted to the first coupler through the Lyot depolarizer, the first coupler outputs a simultaneous transmission signal of the light source to the first detector, and the light signal is fed back to the SLD light source through the processing circuit and the driving circuit, so that the center wavelength of the SLD light source is automatically adjusted.
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| CN202020973269.9U CN212321706U (en) | 2020-06-01 | 2020-06-01 | Passive electronic current transformer |
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| CN202020973269.9U CN212321706U (en) | 2020-06-01 | 2020-06-01 | Passive electronic current transformer |
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Effective date of registration: 20231207 Address after: 510700 3 / F, 4 / F, 5 / F, building J1 and 3 / F, building J3, No. 11, Kexiang Road, Huangpu District, Guangzhou City, Guangdong Province Patentee after: Southern Power Grid Energy Storage Co.,Ltd. Western Maintenance and Testing Branch Address before: 562400 No.1 Beijing Road, Jushan street, Xingyi City, Qianxinan Buyi and Miao Autonomous Prefecture, Guizhou Province Patentee before: China Southern power grid peak load regulation and frequency modulation power generation Co.,Ltd. Western maintenance test branch Patentee before: TIANSHENGQIAO HYDROPOWER GENERATION Co.,Ltd. Patentee before: NR ENGINEERING Co.,Ltd. |
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