Single optical path dual-channel optical current sensor device and self-compensation test method

Abstract

This invention discloses a single-path dual-channel optical current sensor device and a self-compensation testing method. The method and device can achieve four-AD sampling and bidirectional demodulation of the same current sensor optical path, and automatically compensate for temperature-induced errors. The method includes an optical path unit, a circuit unit, and a data processing unit. The optical path uses a coupler to split the light source into two beams. Utilizing the symmetry of the sensing optical path, dual-channel demodulation is achieved, and an isolator is used to achieve unidirectional light output, avoiding bidirectional light interference with the light source and signal power. Each channel uses dual-AD differential demodulation, and a beam splitter ensures that the differential signals are of equal magnitude. Coupler 2 is used to monitor the light source power. The circuit unit includes a light source driver, temperature control and drive closed-loop control, a signal filtering and amplification unit, and a DSP or microcontroller for AD acquisition and signal processing. The data processing unit includes a current signal demodulation algorithm and a self-compensation method.

Description

Technical Field

[0001] This invention relates to the field of power equipment, and in particular to a single-path dual-channel optical current sensor device and a self-compensation testing method. Background Technology

[0002] Currently, power systems are gradually becoming intelligent and digital, with various intelligent sensing and detection devices emerging in large numbers. As a key piece of equipment in the power system, current transformers are used to measure current magnitude, providing essential information for power metering, control, and protection. They must also adapt to technological needs, developing towards miniaturization and intelligence, leading to the continuous invention of current sensors based on different principles. Currently, fiber optic current transformers, with their advantages of simple insulation, small size, safety and reliability, digitalization, intelligence, and integrated metering, measurement, and protection, are already being used in large quantities in intelligent substations, representing the future direction of current transformer development.

[0003] However, due to the complex manufacturing process and high cost of fiber optic current transformers, they are more commonly used in high-voltage fields and have not been widely adopted in low-voltage distribution networks. Therefore, it is necessary to design a current sensor with lower cost and flexible installation, while also achieving dual AD dualization configuration. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and provide a single-path dual-channel optical current sensor device and a self-compensation testing method. This device achieves the function of outputting two independent sampling and protection data channels from a single sensor, and also realizes temperature self-compensation. This invention has the advantages of low cost, high integration, and high level of intelligence.

[0005] The technical solution of this invention is:

[0006] A single-path dual-channel optical current sensor device includes a light source, an isolator 1, a coupler 1, a collimator 1, a Faraday magneto-optical material, a collimator 2, a coupler 2, a detector 3, an isolator 2, and a detector 1.

[0007] Coupler 1 and coupler 2 each have two input ports and two output ports. The light emitted from the light source passes through isolator 1, enters from port 1 of coupler 1, is split evenly, and is emitted from ports 3 and 4 of coupler 1. The light emitted from port 4 of coupler 1 enters collimator 1 in the forward direction, then passes through the Faraday magneto-optical material and enters collimator 2, then enters coupler 2 again. After passing through coupler 2, the light is split into two parts. One part of the light enters detector 3 through port 2 of coupler 2, and the other part of the light is dissipated because isolator 2 is a unidirectional input device. The light emitted from port 3 of coupler 1 passes through isolator 2, enters in the reverse direction from port 1 of coupler 2, and passes through collimator 2, Faraday magneto-optical material, collimator 1, coupler 1 in sequence, and finally enters detector 1.

[0008] A polarization beam splitter 1 is provided between the collimator 1 and the Faraday magneto-optical material. The light emitted from the collimator 1 is split into two parts, transmitted light and reflected light, by the polarization beam splitter 1. The transmitted light enters the Faraday magneto-optical material, and the reflected light enters the beam splitter 1 and is split into transmitted light and reflected light by the beam splitter 1. The transmitted light is not used, and the reflected light enters the detector 2 through the collimator 4.

[0009] A polarization beam splitter 2 is provided between the Faraday magneto-optical material and the collimator 2. The light emitted from the Faraday magneto-optical material is split into two parts, transmitted light and reflected light, by the polarization beam splitter 2. The transmitted light enters the collimator 2, and the reflected light enters the beam splitter 2. The beam splitter 2 splits the transmitted light and reflected light into transmitted light and reflected light. The transmitted light is not used, and the reflected light enters the detector 4 through the collimator 3.

[0010] Coupler 1, coupler 2, polarization beam splitter 1, polarization beam splitter 2, beam splitter 1, and beam splitter 2 are all devices with a beam splitting ratio of 50:50.

[0011] The detectors 1, 2, 3, and 4 are respectively connected to the signal amplification and filtering module and the AD sampling conversion circuit. The signal amplification and filtering module is used to filter and amplify the sensing signals of detectors 1, 2, 3, and 4, and then the AD sampling conversion circuit collects the signals and sends the signals to the data processing unit for control and demodulation.

[0012] After the detector 5 acquires the signal through an AD sampling conversion circuit, it sends the signal to the data processing unit. The data processing unit averages the data acquired by the AD sampling conversion circuit to obtain the cumulative average value. The cumulative average value is used as a signal to adjust the power fluctuation of the light source or the light source failure. The magnitude of the fluctuation of the cumulative average value is used to control the magnitude of the light source drive current.

[0013] A self-compensation test method for a single-path dual-channel optical current sensor device includes:

[0014] The apparatus according to claim 2 or 3 obtains signal representation I from detectors 1 and 2, or detectors 3 and 4;

[0015] Based on the phase change and signal representation I after light passes through a Faraday magneto-optical material, the signal representation I after deformation is obtained;

[0016] Considering temperature characteristics and dual optical paths, based on the signal representation I after deformation, the signal representations of the two detectors are obtained as I1 and I2, respectively.

[0017] Considering the actual splitting ratio, we obtain I2';

[0018] According to I2', the current output is

[0019] The current output includes DC quantities related to temperature and AC quantities independent of temperature; therefore, the DC quantity C... DC =Mean(C), AC quantity C AC =C-Mean(C);

[0020] The final output is C out = (1+K·C) DC C AC K is based on the direct current C DC The correction coefficients obtained from the fitting.

[0021] The I = I0 / 2[1±sin(2θ)],

[0022] Where θ = VBd, V is the Wilder constant, B is the magnetic field strength generated by the current to be measured, d is the length of the magneto-optical material, and I0 is the light intensity after passing through the polarization beam splitter.

[0023] The phase of the light changes to θ = φ + VBd after passing through the Faraday magneto-optical material, where φ is the deflection angle caused by the material's natural optical rotation properties.

[0024] The deformed signal I is represented as: I = I0 / 2{1±sin2(φ+VBd)}.

[0025] The I1=I0 / 2{1+sin2[(φd+Δφ·φTd)+(VBd+ΔV·ΔTBd]};

[0026] I2=I0 / 2{1-sin2[(φd+Δφ·φTd)+(VBd+ΔV·ΔTBd]}.

[0027] The Among them, I 1DC For I1 DC flow, I 2DC The I2 DC flow rate is obtained by averaging the complete cycle data of I1 and I2.

[0028] C DC =Mean(C)=φd+Δφ·ΔTd;

[0029] C AC =C-Mean(C)=VBd+ΔV·ΔTBd.

[0030] The single-path dual-channel optical current sensor device and self-compensation test method are based on a single-path Faraday magneto-optical sensing material. The optical path is bidirectionally sensed, and the bidirectional sensing information is sampled by independent dual AD converters. The sampled values ​​are demodulated independently, realizing the output of two independent sampling current protection data from a single set of sensors. The entire device mainly consists of an optical path, a circuit, and a data processing unit.

[0031] The device employs bidirectional dual-channel differential demodulation, with both channels sharing a single light source. The beam is split by fiber coupler 1. To ensure the return of the input light from the opposite direction, an isolator is added to reduce interference and stabilize the output of the light source and signal light. The bidirectional optical signal is split into two differential signals, a direct-through signal and a reflected signal, by a polarization beam splitter. The direct-through portion enters the detector via the coupler, while the reflected portion enters the detector via the beam splitter. Both the coupler and the beam splitter have a near 50:50 splitting ratio to ensure equal differential signal magnitudes. A detector 5 is added to port 4 of coupler 2 to monitor optical power for closed-loop control of the light source power and to serve as an alarm signal for light source failure.

[0032] The circuit includes a light source driving, cooling, and optical power closed-loop control module, a signal amplification and filtering module, and five independent AD sampling and conversion circuits. The light source driving and cooling module drives the light source to emit light and controls its temperature, while simultaneously using a closed-loop control system to stabilize the light source power.

[0033] The signal amplification and filtering circuit is used for detector signal noise control; of the 5-channel AD sampling module, one channel is used to detect the light source power and control the light source drive, while the other 4 channels sample dual-channel differential sensing signals, demodulating two independent current signals respectively. The demodulated data can be used as a dual AD sampling current output, and the sum and average of the two demodulated data can also be used as a single signal output to reduce noise. AD sampling is performed simultaneously at the same time through timing control.

[0034] The data processing unit is used to control and demodulate the acquired signals, including a demodulation algorithm and a self-compensating temperature method. The bidirectional differential signals are sampled by an AD converter, and the sampled data is demodulated differentially. The current and error terms are demodulated separately, and the device temperature is self-compensated by the error terms to correct the demodulated current signal.

[0035] In summary, this application includes at least the following beneficial technical effects:

[0036] (1) It solves the problem of high cost of existing fiber optic current transformers and meets the needs of intelligent distribution network (self-diagnosis, ability to detect more signals and statuses, etc.), digitalization, and dual configuration applications;

[0037] (2) It realizes the function of outputting two independent sampling and protection data from a single sensor, and achieves temperature self-compensation. This invention has the advantages of low cost, high integration, and high level of intelligence. Attached Figure Description

[0038] Figure 1 - Schematic diagram of a single-path dual-channel optical current sensor device;

[0039] Figure 2 - Circuit principle of single-path dual-channel optical current sensor device. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0041] This application discloses a single-path dual-channel optical current sensor device and a self-compensation testing method, such as... Figure 1 As shown, the device includes an optical path, a circuit, and a data processing section.

[0042] The optical path mainly includes components such as a light source, isolator / coupler, detector, collimator, polarization beamsplitter, and detector. Specifically, it includes a light source, isolator 1, detector 1, coupler 1, collimator 1, polarization beamsplitter 1, Faraday magneto-optical material, polarization beamsplitter 2, collimator 2, coupler 2, isolator 2, detector 3, detector 5, beamsplitter 2, collimator 3, detector 4, beamsplitter 1, collimator 4, and detector 2. The schematic diagram is shown below. Figure 1 As shown.

[0043] Its working principle is as follows: Under the action of the driving cooling circuit, the light emitted by the light source passes through isolator 1 and enters from port 1 of coupler 1. After being split evenly, it is emitted from ports 3 and 4 of coupler 1. The light emitted from port 4 enters collimator 1 in the forward direction and is evenly split into transmission and reflection parts by polarization beam splitter 1. The reflected light dissipates and is not utilized. The transmission light enters the magneto-optical material and reaches polarization beam splitter 2. At this time, the light is again evenly split into transmission and reflection parts. Half of the light is transmitted into collimator 2 and then into coupler 2. After passing through coupler 2, the light is also evenly split into two parts. Half of the light enters detector 3 through port 2 of coupler 2, and the other half of the light returns through port 1 of coupler 2. However, since isolator 2 is a unidirectional input device, this part of the light will be dissipated and will not return to detector 1. The light reflected by polarization beam splitter 2 enters beam splitter 2 and is... Beam splitter 2 evenly splits the transmitted light into transmitted and reflected light. The transmitted light is not utilized, and the reflected light enters detector 4 through collimator 3. The coupler, polarization beam splitter, and beam splitter in the optical path are all devices with a splitting ratio of 50:50. Therefore, after removing the optical path doping loss, the light power entering detectors 3 and 4 is 1 / 16 of the light emitted by the light source, which is basically equal. In addition, since the polarization axes of polarization beam splitter 1 and polarization beam splitter 2 are 45° apart, according to Malus's law, the light signals entering detectors 3 and 4 are differential signals, which can be expressed as I=I0 / 2[1±sin(2θ)], θ=VBd, V is the Verdet constant, B is the magnetic field strength, d is the length of the Faraday magneto-optical material, I0 is the light before entering the Faraday magneto-optical material, and I is the light output from the Faraday magneto-optical material after interference by the polarization beam splitter.

[0044] Similarly, the light emitted from port 3 of coupler 1 is reversed through coupler 2 into the sensing optical path and eventually enters detectors 1 and 2, also with I = I0 / 2[1±sin(2θ)]. Due to the presence of isolator 1, the returned light does not affect the light source. The returned light passes through an extra coupler, so the light entering detectors 1 and 2 is 1 / 32 of the light emitted by the light source.

[0045] By configuring the optical path as described above, it is possible to measure two beams of light using only a single common component of the Faraday magneto-optical material. Compared to a completely redundant optical path with identical components, this design simplifies the optical path structure and saves on the number of components required.

[0046] The circuit section includes a unique light source driver module, a cooling module, a power closed-loop control module, a signal amplification and filtering module, and a 5-channel independent AD sampling and conversion circuit. The principle is as follows: Figure 2 As shown. The light source driving module controls the light intensity emitted by the light source by adjusting the current. The cooling module is used to cool the light source driving module, ensuring the temperature of the light source chip is stable, and making the power and wavelength fluctuations of the emitted light source more stable. The power closed-loop control module is used to provide feedback on the power of the light source, adjust the light source driving module according to the feedback results, and monitor whether the light source has a fault. Its function is implemented by detector 5. The signal of detector 5 is the light signal after the light source passes through isolator 1, coupler 1, isolator 2, and coupler 2. It reflects the light source's light power and stability. The signal is collected by AD5. The data processing unit averages the data collected by the AD sampling conversion circuit to obtain the cumulative average value. The cumulative average value is used as the signal to adjust the light source power fluctuation or light source fault. According to the proportional relationship between the light source power and the driving current, the magnitude of the cumulative average value fluctuation is used to control the light source driving current and keep the light source output light power constant.

[0047] The sensor signals from dual-channel detectors 1, 2, 3, and 4 are filtered and amplified before being acquired by AD1, AD2, AD3, and AD4 respectively. The acquisition clocks are controlled to be synchronized to ensure that the demodulation currents are in the same phase.

[0048] The acquired signals are controlled and demodulated by a data processing unit, which is composed of a microcontroller or DSP. The data from AD1 and AD2 are demodulated independently from the data from AD3 and AD4.

[0049] Self-compensation testing methods include:

[0050] According to Lawyer Ma's Law, the arrival at detectors 1 and 2 can be represented as:

[0051] I=I0 / 2[1±sin(2θ)] (1)

[0052] θ = VBd, where V is the Verdet constant, B is the magnetic field strength generated by the current to be measured, d is the length of the Faraday magneto-optical material, and I0 is the light intensity after passing through the polarization beam splitter. However, in practical applications, the Verdet constant of the Faraday magneto-optical material used for sensing exhibits temperature dependence. Reports indicate that the Verdet constant varies significantly, and the ambient temperature of the sensor head cannot be directly measured. It needs to be indirectly measured in the demodulation scheme to compensate for errors caused by the temperature of the current sensor.

[0053] Since light exhibits optical rotation when passing through any material, albeit at different angles, the phase of light changes after passing through a Faraday magneto-optical material.

[0054] θ=φ+VBd (2)

[0055] (2) In the formula, φ is the deflection angle caused by the natural optical rotation properties of the material. With formula (2), then, formula (1) becomes:

[0056] I=I0 / 2{1±sin2(φ+VBd)} (3)

[0057] Considering the temperature characteristics and the dual optical path, equation (3) becomes:

[0058] I1=I0 / 2{1+sin2[(φd+Δφ·ΔTd)+(VBd+ΔV·ΔTBd]} (4)

[0059] I2=I0 / 2{1-sin2[(φd+Δφ·ΔTd)+(VBd+ΔV·ΔTBd]} (5)

[0060] Wherein, ΔT is the temperature change, which is determined based on the temperature change of the environment; ΔV is the change of Wilder's constant with temperature.

[0061] Considering that the actual splitting ratio will not be 50:50, let

[0062]

[0063] Among them, I 1DC For the direct current in equation (4), I 2DC The DC flow rate of equation (5) can be obtained by averaging the complete cycle data of the signals in equations (4) and (5).

[0064] The current output can then be obtained from the following formula.

[0065]

[0066] When α is small in engineering, it can be represented by sin(α)≈α.

[0067] C=[(φd+Δφ·ΔTd)+(VBd+ΔV·ΔTBd)] (8)

[0068] Equation (8) includes DC quantities related to temperature and AC quantities independent of temperature, therefore the DC quantity C DC =Mean(C)=φd+Δφ·ΔTd (9)

[0070] Exchange volume C AC =C-Mean(C)=VBd+ΔV·ΔTBd (10)

[0072] The temperature curve is obtained by demodulating equation (9) to compensate for equation (10), thus eliminating the influence of temperature.

[0073] The final output is

[0074] C out = (1+K·C) DC C AC (11)

[0075] K is a correction coefficient obtained by fitting the DC temperature change (i.e., Equation 9).

[0076] This invention addresses the high cost of existing fiber optic current transformers and proposes a single-path dual-channel optical current sensor device and a self-compensation testing method. The method and device enable dual sampling and demodulation of the same sensing optical path, and can perform error self-compensation. The solution of this invention has the advantages of simple structure, low cost, and high level of intelligence.

[0077] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0078] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A single-path dual-channel optical current sensor device, characterized in that: It includes a light source, isolator 1, coupler 1, collimator 1, Faraday magneto-optical material, collimator 2, coupler 2, detector 3, isolator 2, and detector 1; Coupler 1 and coupler 2 each have 2 input ports and 2 output ports; The light emitted from the light source passes through isolator 1, enters from port 1 of coupler 1, is split evenly, and is emitted from ports 3 and 4 of coupler 1. The light emitted from port 4 of coupler 1 enters collimator 1 in the forward direction, then passes through Faraday magneto-optical material and enters collimator 2, and then enters coupler 2. After entering coupler 2, the light is split into two parts. One part of the light enters detector 3 through port 2 of coupler 2, and the other part of the light is dissipated because isolator 2 is a unidirectional input device. The light emitted from port 3 of coupler 1 passes through isolator 2, enters in reverse from port 1 of coupler 2, and passes sequentially through collimator 2, Faraday magneto-optical material, collimator 1, coupler 1, and finally enters detector 1; The detectors 1, 2, 3, and 4 are respectively connected to the signal amplification and filtering module and the AD sampling conversion circuit. The signal amplification and filtering module is used to filter and amplify the sensing signals of detectors 1, 2, 3, and 4, and then the AD sampling conversion circuit collects the signals and sends the signals to the data processing unit for control and demodulation. After the detector 5 acquires the signal through an AD sampling conversion circuit, it sends the signal to the data processing unit. The data processing unit averages the data acquired by the AD sampling conversion circuit to obtain the cumulative average value. The cumulative average value is used as a signal to adjust the power fluctuation of the light source or the light source failure. The magnitude of the fluctuation of the cumulative average value is used to control the magnitude of the light source drive current.

2. The single-path dual-channel optical current sensor device according to claim 1, characterized in that: A polarization beam splitter 1 is provided between the collimator 1 and the Faraday magneto-optical material. The light emitted from the collimator 1 is split into two parts, transmitted light and reflected light, by the polarization beam splitter 1. The transmitted light enters the Faraday magneto-optical material, and the reflected light enters the beam splitter 1 and is split into transmitted light and reflected light by the beam splitter 1. The transmitted light is not used, and the reflected light enters the detector 2 through the collimator 4.

3. A single-path dual-channel optical current sensor device according to claim 1 or 2, characterized in that: A polarization beam splitter 2 is provided between the Faraday magneto-optical material and the collimator 2. The light emitted from the Faraday magneto-optical material is split into two parts, transmitted light and reflected light, by the polarization beam splitter 2. The transmitted light enters the collimator 2, and the reflected light enters the beam splitter 2. The beam splitter 2 splits the transmitted light and reflected light into transmitted light and reflected light. The transmitted light is not used, and the reflected light enters the detector 4 through the collimator 3.

4. The single-path dual-channel optical current sensor device according to claim 3, characterized in that: Coupler 1, coupler 2, polarization beam splitter 1, polarization beam splitter 2, beam splitter 1, and beam splitter 2 are all devices with a beam splitting ratio of 50:

50.

5. A self-compensation test method for a single-path dual-channel optical current sensor device, characterized in that: include The apparatus according to claim 2 or 3 obtains signal representation I from detectors 1 and 2, or detectors 3 and 4; Based on the phase change and signal representation I after light passes through a Faraday magneto-optical material, the signal representation I after deformation is obtained; Considering temperature characteristics and dual optical paths, based on the signal representation I after deformation, the signal representations of the two detectors are obtained as I1 and I2, respectively. Considering the actual splitting ratio, we obtain I2. ’ ; According to I2 ’ Current output is ; The current output includes DC quantities related to temperature and AC quantities independent of temperature; therefore, the DC quantity... ; The final output is K is based on the direct current C DC The correction coefficients obtained from the fitting.

6. The self-compensation test method for a single-path dual-channel optical current sensor device according to claim 5, characterized in that: The , in, , For Wilder's constant, denoted as , where is the magnetic field strength, generated by the current to be measured; d is the length of the magneto-optical material; and I0 is the light intensity after passing through the polarization beam splitter.

7. The self-compensation test method for a single-path dual-channel optical current sensor device according to claim 6, characterized in that: The phase of the light changes after passing through the Faraday magneto-optical material. , The deflection angle caused by the material's natural optical rotation properties; The deformed signal I is represented as: .

8. The self-compensation test method for a single-path dual-channel optical current sensor device according to claim 7, characterized in that: The ； 。 9. The self-compensation test method for a single-path dual-channel optical current sensor device according to claim 6, characterized in that: The , among which, I 1DC for Direct current, I 2DC for Direct flow, through The average of the complete cycle data is obtained; ； 。

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