CN112881771A - High-precision high-voltage transformer acquisition system based on phase detection - Google Patents
High-precision high-voltage transformer acquisition system based on phase detection Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
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Abstract
The invention provides a high-precision high-voltage transformer acquisition system based on phase detection, which is characterized in that through arranging an analog switch circuit and selecting an analog switch switching mode to cut off peak pulses, compared with the existing peak filtering mode, the high-precision high-voltage transformer acquisition system can filter off the peak pulses superposed on direct current, thereby providing the detection precision of the system; the band-pass filter filters a direct current component in the voltage signal output by the analog switch circuit and outputs the filtered alternating current signal to a first digital input end of the processor, and the processor obtains the alternating current component according to the digital signal; the low-pass filter extracts the direct current component in the voltage signal output by the analog switch circuit and inputs the direct current component to the second digital input end of the processor, the processor obtains the direct current component according to the digital signal, and divides the alternating current component by the direct current component, so that the influence of the direct current component on the acquisition system can be eliminated, and the measurement precision of the system is improved.
Description
Technical Field
The invention relates to the technical field of voltage transformer detection, in particular to a high-precision high-voltage transformer acquisition system based on phase detection.
Background
The electronic current transformer is widely applied to the transformer substation due to the characteristics of no need of an iron core, good insulating property and simple structure. Electronic current transformers can be divided into three categories: an Optical Current Transformer (OCT), an air-core coil current transformer (air-core OCT), and an iron-core coil current transformer (low power consumption current transformer LPTA). The hollow-core OCT is also called an active electronic current transformer, and performs sampling transmission on a high-voltage side by a primary converter, the sampled electrical signal is converted into an optical signal by an electro-optical converter, the optical signal is modulated by a square wave signal and then input into an optical fiber, the high-voltage side signal is transmitted to a low-voltage side by the optical fiber, the optical fiber is only used as a medium for transmitting to the low-voltage side, and then performs photoelectric conversion on the low-voltage side by a photodiode, converts a photocurrent into a voltage signal, and performs signal processing and displays the voltage signal on a display. After the high-voltage side optical signal is modulated by square waves, the output current signal of the photodiode is doped with spike pulses and direct current signals, the amplitude of which is far greater than that of useful signals, and if the spike pulses are not processed, the spike pulses can be widened by a post-stage amplifying circuit, so that the detection precision is directly influenced; without processing the dc signal, it is difficult to extract the useful signal, and the detection accuracy is also directly affected. The existing methods adopt a method for directly filtering spike pulses and direct current signals, and if the direct current signals are directly filtered and only the alternating current signals are processed, the stability of a high-voltage transformer acquisition system and even the accuracy of a detection result are affected. Therefore, in order to solve the problems, the invention provides a high-precision high-voltage transformer acquisition system based on phase detection, and a novel scheme is adopted to filter spike pulses and direct current signals, so that the detection precision and stability of the system are improved.
Disclosure of Invention
In view of the above, the invention provides a high-precision high-voltage transformer acquisition system based on phase detection, and a novel scheme is adopted to filter spike pulses and direct-current signals, so that the detection precision and stability of the system are improved.
The technical scheme of the invention is realized as follows: the invention provides a high-precision high-voltage transformer acquisition system based on phase detection, which comprises an electronic current transformer, a high-voltage side signal processing circuit, an optical fiber, a low-voltage side signal processing circuit and a processor, wherein the low-voltage side signal processing circuit comprises: the device comprises a photoelectric conversion module, an analog switch circuit, a band-pass filter, a low-pass filter, an automatic gain control circuit and a first A/D converter;
the electronic current transformer collects a current signal on a bus and inputs the current signal to a high-voltage side signal processing circuit, the high-voltage side signal processing circuit processes, electro-optic converts and modulates the input current signal into an optical signal, the optical signal is input to one end of an optical fiber, the optical signal is converted into a voltage signal at the other end of the optical fiber through a photoelectric conversion module, the voltage signal is output to an analog switch circuit, the analog switch circuit compares the input voltage signal with a preset voltage amplitude value, when the input voltage signal amplitude value is larger than the preset voltage value, a spike pulse signal is cut through a change-over switch, and the cut voltage signal is respectively input to a band-pass filter and a low-pass filter;
the band-pass filter filters a direct current component in a voltage signal output by the analog switch circuit, the filtered voltage signal is output to the automatic gain control circuit to be amplified, the amplified signal is sent to the first A/D converter to be subjected to analog-to-digital conversion, a converted digital signal is input to a first digital input end of the processor, and the processor obtains an alternating current component according to the digital signal;
the low-pass filter extracts a direct-current component in a voltage signal output by the analog switch circuit, inputs the direct-current component into the first A/D converter for analog-to-digital conversion, inputs a converted digital signal into the second digital input end of the processor, and the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component to eliminate the influence of the direct-current component on an acquisition system.
On the basis of the above technical solution, preferably, the low-voltage side signal processing circuit further includes a phase shift circuit;
the band-pass filter filters direct current components in the voltage signals output by the analog switch circuit, the filtered voltage signals are output to the phase shift circuit for phase compensation, and the voltage signals after phase compensation are input to the automatic gain control circuit for amplification.
On the basis of the above technical solution, preferably, the photoelectric conversion module includes a photodiode, an I/V conversion circuit, and an amplification circuit;
and converting the optical signal into a photocurrent signal at the other end of the optical fiber through a photodiode, converting the photocurrent signal into a voltage signal through an I/V conversion circuit, and amplifying the voltage signal through an amplifying circuit and outputting the voltage signal to an analog switch circuit.
Further preferably, the analog switch circuit comprises a single-pole double-throw switch, a reference voltage circuit, a voltage comparator and a voltage follower;
the voltage signal output by the amplifying circuit is respectively input to the inverting input end of the voltage comparator and the input end of the voltage follower, the non-inverting input end of the voltage comparator is electrically connected with the reference voltage circuit, the output end of the voltage follower is electrically connected with the normally open contact of the single-pole double-throw switch, the normally closed contact of the single-pole double-throw switch is grounded, and the output end of the voltage comparator is electrically connected with the control end of the single-pole double-throw switch.
Further preferably, the reference voltage circuit includes: a resistor R11, a resistor R12 and a 5V power supply;
the 5V power supply is electrically connected with one end of the resistor R11 and the non-inverting input end of the voltage comparator through a resistor R12, and the other end of the resistor R11 is grounded.
Further preferably, the single pole double throw switch comprises: a high-speed analog switch TS5a 3154;
the NC pin of the high-speed analog switch TS5A3154 is grounded, the NO pin is electrically connected with the output end of the voltage follower, and the IN pin of the high-speed analog switch TS5A3154 is electrically connected with the output end of the voltage comparator.
On the basis of the above technical solution, preferably, the high-voltage side signal processing circuit includes: the device comprises an integrating amplifier, a bias circuit, a second A/D converter, a driving circuit and an electro-optical conversion module;
the integrating amplifier integrates and amplifies current signals on a collecting bus of the electronic current transformer and outputs alternating current signals to the biasing circuit, the biasing circuit converts the alternating current signals into unipolar positive power supply signals and outputs the unipolar positive power supply signals to the second A/D converter for analog-to-digital conversion, and the output digital signals control the driving circuit to drive the electro-optical conversion module to convert the electric signals into optical signals and output the optical signals to one end of the optical fiber.
Further preferably, the integrator comprises resistors R13-R17, a capacitor C4, a capacitor C5 and an operational amplifier TLV 2333;
the electronic current transformer is electrically connected with the inverting input end of an operational amplifier TLV2333 through a resistor R17, the non-inverting input end of the operational amplifier TLV2333 is grounded through a resistor R13, a capacitor C5 is electrically connected with the inverting input end and the output end of the operational amplifier TLV2333 in parallel, a resistor R14 and a resistor R15 are connected in series and then connected between the inverting input end and the output end of the operational amplifier TLV2333 in parallel, one end of a resistor R16 is electrically connected with the middle connection point of the resistor R14 and the resistor R15, and the other end of the resistor R16 is grounded through a capacitor C4.
Compared with the prior art, the high-precision high-voltage transformer acquisition system based on phase detection has the following beneficial effects:
(1) by improving the structure of the integrating amplifier, the problem of overflow of the digital integrator caused by input low-frequency components can be reduced, so that the integrating amplifier has higher inhibition capability on the low-frequency components;
(2) by arranging the analog switch circuit and selecting the analog switch switching mode to cut the spike pulse, compared with the existing spike filtering mode, the spike pulse superposed on the direct current can be filtered, and the system detection precision is further provided;
(3) the band-pass filter filters a direct current component in the voltage signal output by the analog switch circuit and outputs the filtered alternating current signal to a first digital input end of the processor, and the processor obtains the alternating current component according to the digital signal; the low-pass filter extracts a direct-current component in the voltage signal output by the analog switch circuit and inputs the direct-current component to the second digital input end of the processor, the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component, the influence of the direct-current component on the acquisition system can be eliminated, and the measurement precision of the system is improved;
(4) the phase shift circuit is arranged to perform phase compensation on the input signal, so that the phase difference caused by the links of differentiation, integration, filtering and the like is reduced, and the measurement precision of the system is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a structural diagram of a high-precision high-voltage transformer acquisition system based on phase detection according to the present invention;
FIG. 2 is a structural diagram of a low-voltage side signal processing circuit in a high-precision high-voltage transformer acquisition system based on phase detection according to the invention;
FIG. 3 is a circuit diagram of an analog switch circuit in the high-precision high-voltage transformer acquisition system based on phase detection according to the invention;
fig. 4 is a circuit diagram of an integrating amplifier in a high-precision high-voltage transformer acquisition system based on phase detection.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
As shown in fig. 1, the high-precision high-voltage transformer acquisition system based on phase detection of the present invention includes an electronic current transformer, a high-voltage side signal processing circuit, an optical fiber, a low-voltage side signal processing circuit, and a processor.
And the electronic current transformer is used for collecting the current on the bus. The electronic current transformer can be realized by adopting the prior art, and in the embodiment, a Rogowski coil is selected as the electronic current transformer.
And the high-voltage side signal processing circuit samples on the high-voltage side through the primary converter, processes, electro-optically converts and modulates the sampled signal to form an optical signal, and the modulated optical signal is transmitted to the low-voltage side signal processing circuit through an optical fiber and is further processed by the low-voltage side signal processing circuit. In this embodiment, the high-voltage side signal processing circuit includes: the device comprises an integrating amplifier, a bias circuit, a second A/D converter, a driving circuit and an electro-optical conversion module.
The integrating amplifier is used for measuring the measured current signal, because the output signal of the electronic current transformer and the measured current signal are in a differential relation, the integrating amplifier is required to be used. The existing integrator comprises an analog integrator and a digital integrator, and the analog integrator has the phenomena of integral drift, nonlinear error, high-frequency error, capacitance leakage and the like due to the fact that the analog integrator has too large amplification factor of a low-frequency signal, so that the accuracy of the integrator is deteriorated and the zero drift is too large; compared with an analog integrator, the digital integrator has the advantages of simple structure, small influence by temperature drift and time drift, stable performance, excellent phase characteristics, flexible structure, convenience in adjustment and the like, but the traditional digital integrator can infinitely amplify direct current components, continuously shifts along with the running time, and finally exceeds the numerical range which can be represented by a register to overflow. Therefore, in order to reduce the problem of overflow of the digital integrator caused by the input low-frequency component, in the embodiment, the conventional digital integrator is improved to have higher suppression capability on the low-frequency component. Preferably, as shown in fig. 4, the integrator comprises resistors R13-R17, a capacitor C4, a capacitor C5 and an operational amplifier TLV 2333; specifically, the electronic current transformer is electrically connected with the inverting input end of the operational amplifier TLV2333 through a resistor R17, the non-inverting input end of the operational amplifier TLV2333 is grounded through a resistor R13, a capacitor C5 is electrically connected in parallel with the inverting input end and the output end of the operational amplifier TLV2333, a resistor R14 and a resistor R15 are connected in series and then connected in parallel between the inverting input end and the output end of the operational amplifier TLV2333, one end of a resistor R16 is electrically connected with the middle connection point of the resistor R14 and the resistor R15, and the other end of the resistor R16 is grounded through a capacitor C4.
The resistor R17, the operational amplifier TLV2333, and the capacitor C5 form a typical analog integrator, and in this embodiment, a digital filter is designed by using a conventional analog integrator.
In the bias circuit, since the output voltage of the integrating amplifier is an ac signal, and the input of the second a/D converter at the rear stage is required to be a unipolar positive power supply signal, in this embodiment, the bias circuit is configured to perform dc bias on the ac signal. Can be implemented by using the prior art, and will not be described in detail herein.
And a second A/D converter for converting the input analog signal into a digital signal and transmitting the digital signal to the driving circuit. The second a/D converter can be implemented using known techniques and will not be described again here.
And the driving circuit receives the digital signal output by the second A/D converter and generates a driving signal for driving the electro-optical conversion module to work. Can be implemented by using the prior art, and will not be described in detail herein.
The optical fiber, which is a medium for transmission only to the low voltage side. Preferably, multimode optical fibers may be used. The high-voltage side signal processing circuit processes, electro-optically converts and modulates the input current signal into an optical signal, the optical signal is input to one end of the optical fiber, and the optical signal is collected and processed at the other end of the optical fiber through the low-voltage side signal processing circuit.
And the low-voltage side signal processing circuit is used for collecting optical signals, processing and displaying the optical signals.
The working principle of the embodiment is as follows: the high-voltage side signal processing circuit samples on the high-voltage side through a primary converter, an integrating amplifier converts a differential relation between an output signal of an electronic current transformer and a measured current signal into an original signal, a biasing circuit converts an alternating current signal output by the integrating amplifier into a unipolar positive power supply signal, the unipolar positive power supply signal is converted by a second A/D converter and then input into a driving circuit, the driving circuit generates a driving signal for driving an electro-optical conversion module to work, the electro-optical conversion module converts an electric signal into an optical signal and inputs the optical signal to one end of an optical fiber, and the other end of the optical fiber is collected and processed by a low-voltage side signal processing circuit.
The beneficial effect of this embodiment does: by improving the structure of the integrating amplifier, the problem of overflow of the digital integrator caused by input low-frequency components can be reduced, so that the integrating amplifier has higher inhibition capability on the low-frequency components.
Example 2
On the basis of embodiment 1, this embodiment provides a specific structure of a low-voltage side signal processing circuit and a method for eliminating spikes and dc components, specifically, as shown in fig. 2, the low-voltage side signal processing circuit includes: the device comprises a photoelectric conversion module, an analog switch circuit, a band-pass filter, a low-pass filter, a phase-shifting circuit, an automatic gain control circuit and a first A/D converter.
And the photoelectric conversion module is used for collecting optical signals and carrying out photoelectric conversion and amplification processing on the optical signals. In this embodiment, the photoelectric conversion module includes a photodiode, an I/V conversion circuit, and an amplification circuit. And the other end of the optical fiber converts an optical signal into a photocurrent signal through a photodiode, the photocurrent signal is a square wave current signal with direct current bias and spike pulse, the square wave current signal is converted into a voltage signal through an I/V conversion circuit, and the voltage signal is amplified through an amplifying circuit and output to an analog switch circuit.
In the analog switch circuit, after the high-voltage side optical signal is modulated by the square wave, the peak pulse and the direct current signal with the amplitude far larger than that of the useful signal are mixed in the output current signal of the photodiode, so that the peak pulse and the direct current signal mixed in the useful signal need to be filtered. The common way of filtering the spike pulse is four, the first one is to select a schottky diode with soft recovery characteristic or adopt a method of connecting an inductor in series in front of a rectifier tube; secondly, an RC absorption loop is connected to the secondary side; thirdly, a plurality of rectifier diodes are connected in parallel; fourthly, the layout and routing of the elements are reasonable. In this embodiment, the frequency of the spike and the square wave is 200kHz, and the spike is superimposed on the direct current, and the spike cannot be completely filtered by the existing spike filtering method. Therefore, in order to solve the above technical problem, in this embodiment, an analog switch clipping manner is adopted to filter the spike pulse, and an analog switch circuit is provided to filter the spike pulse doped with the useful signal. In this embodiment, the analog switch circuit includes a single-pole double-throw switch, a reference voltage circuit, a voltage comparator and a voltage follower; the voltage signal output by the amplifying circuit is respectively input to the inverting input end of the voltage comparator and the input end of the voltage follower, the non-inverting input end of the voltage comparator is electrically connected with the reference voltage circuit, the output end of the voltage follower is electrically connected with the normally open contact of the single-pole double-throw switch, the normally closed contact of the single-pole double-throw switch is grounded, and the output end of the voltage comparator is electrically connected with the control end of the single-pole double-throw switch. The voltage signal with the spike pulse is output to a normally open contact of the single-pole double-throw switch through the voltage follower, the reference voltage circuit provides threshold voltage for an inverting input end of the voltage comparator, the voltage signal with the spike pulse is compared with the threshold voltage of the voltage comparator, when the amplitude of the voltage signal with the spike pulse is larger than the threshold voltage, the voltage comparator outputs 0, and the single-pole double-throw switch selects the state of outputting the normally closed contact as output, namely the output is 0; when the amplitude of the voltage signal with the spike pulse is smaller than the threshold voltage, the voltage comparator outputs 1, and the single-pole double-throw switch selects and outputs the state of a normally open contact as output, namely the output signal of the amplifying circuit is used as output.
Preferably, as shown in fig. 3, the reference voltage circuit includes: a resistor R11, a resistor R12 and a 5V power supply; the 5V power supply is electrically connected with one end of the resistor R11 and the non-inverting input end of the voltage comparator through a resistor R12, and the other end of the resistor R11 is grounded.
Preferably, as shown in fig. 3, the single pole double throw switch includes: a high-speed analog switch TS5a 3154; the NC pin of the high-speed analog switch TS5A3154 is grounded, the NO pin is electrically connected with the output end of the voltage follower, and the IN pin of the high-speed analog switch TS5A3154 is electrically connected with the output end of the voltage comparator. When the amplitude of the voltage signal with the spike pulse output by the amplifying circuit is larger than the threshold voltage of the voltage comparator, the voltage comparator outputs 0, and the single-pole double-throw switch selects the state of the normally closed contact as output, namely the output is 0; when the amplitude of the voltage signal with the spike pulse is smaller than the threshold voltage, the voltage comparator outputs 1, and the single-pole double-throw switch selects and outputs the state of a normally open contact as output, namely the output signal of the amplifying circuit is used as output.
The voltage signal processed by the analog switch circuit filters spike pulse signals, but has direct current components, and the traditional method adopts a filter to directly filter the direct current components. If the direct current signal is directly filtered, and only the alternating current signal is collected and processed, the result after relevant demodulation is directly related to light intensity, circuit gain, light path loss and the like, so that the stability of the signal detection system is not good enough, and even the accuracy of the detection result is affected. Therefore, in order to solve the above problem, the present embodiment provides a band-pass filter and a low-pass filter, which cooperate with each other to eliminate the influence of the dc component on the system stability. Specifically, an output voltage signal of the analog switch circuit is respectively input to an input end of a band-pass filter and an input end of a low-pass filter, the band-pass filter filters a direct current component in the output voltage signal of the analog switch circuit and outputs the filtered voltage signal to an automatic gain control circuit for amplification, the amplified signal is sent to a first A/D converter for analog-to-digital conversion and inputs a converted digital signal to a first digital input end of a processor, and the processor obtains an alternating current component according to the digital signal; the low-pass filter extracts a direct-current component in a voltage signal output by the analog switch circuit, inputs the direct-current component into the first A/D converter for analog-to-digital conversion, inputs a converted digital signal into the second digital input end of the processor, and the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component to eliminate the influence of the direct-current component on an acquisition system.
Preferably, the band-pass filter can be a band-pass filter formed by combining a two-order butterworth low-pass filter and a two-order butterworth high-pass filter, the lower limit cut-off frequency of the band-pass filter is preferably 2kHz, and the upper limit cut-off frequency of the band-pass filter is preferably 2 MHz; the low-pass filter may be a two-step butterworth low-pass filter, preferably with a cut-off frequency of 100 Hz.
In the signal processing process, the phase shift circuit generates a phase difference due to the existence of differentiation, integration, filtering and other links, so that the phase shift circuit is arranged for phase compensation to reduce the error of the system.
Because the output range of the photodiode is large, in order to meet the voltage requirement of the input pin of the first a/D converter, the automatic gain control circuit is provided in this embodiment to realize the function of converting photocurrent in a large range.
The first A/D converter receives analog signals output by the automatic gain control circuit and the low-pass filter, converts the analog signals into digital signals, outputs the digital signals of the description to the processor, obtains direct-current components according to the digital signals, divides the direct-current components by the alternating-current components, and eliminates the influence of the direct-current components on the acquisition system.
The working principle of the embodiment is as follows: converting an optical signal into a photocurrent signal through a photodiode at the other end of the optical fiber, wherein the photocurrent signal is a square wave current signal with direct current bias and spike pulse, the square wave current signal is converted into a voltage signal through an I/V conversion circuit, the voltage signal is amplified through an amplifying circuit and output to the inverting input end of a voltage comparator and the input end of a voltage follower, a reference voltage circuit provides a threshold voltage for the non-inverting input end of the voltage comparator, when the amplitude of the voltage signal with the spike pulse output by the amplifying circuit is greater than the threshold voltage of the voltage comparator, the voltage comparator outputs 0, and the single-pole double-throw switch selects the state of the normally closed contact as output, namely the output is 0; when the amplitude of the voltage signal with the spike pulse is smaller than the threshold voltage, the voltage comparator outputs 1, the single-pole double-throw switch selects the state of the output normally open contact as output, namely, the output signal of the amplifying circuit is used as output, the spike pulse is cut through a switch switching mode, the voltage signal after the spike pulse is filtered is respectively output to the input end of the band-pass filter and the input end of the low-pass filter, the band-pass filter filters a direct current component in the output voltage signal of the analog switch circuit, the filtered voltage signal is output to the automatic gain control circuit for amplification after phase compensation of the phase shift circuit, the amplified signal is sent to the first A/D converter for analog-to-digital conversion, the converted digital signal is input to the first digital input end of the processor, and the processor obtains an alternating current component according to the digital signal; the low-pass filter extracts a direct-current component in a voltage signal output by the analog switch circuit, inputs the direct-current component into the first A/D converter for analog-to-digital conversion, inputs a converted digital signal into the second digital input end of the processor, and the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component to eliminate the influence of the direct-current component on an acquisition system.
The beneficial effect of this embodiment does: by arranging the analog switch circuit and selecting the analog switch switching mode to cut the spike pulse, compared with the existing spike filtering mode, the spike pulse superposed on the direct current can be filtered, and the system detection precision is further provided;
the band-pass filter filters a direct current component in the voltage signal output by the analog switch circuit and outputs the filtered alternating current signal to a first digital input end of the processor, and the processor obtains the alternating current component according to the digital signal; the low-pass filter extracts a direct-current component in the voltage signal output by the analog switch circuit and inputs the direct-current component to the second digital input end of the processor, the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component, the influence of the direct-current component on the acquisition system can be eliminated, and the measurement precision of the system is improved;
the phase shift circuit is arranged to perform phase compensation on the input signal, so that the phase difference caused by the links of differentiation, integration, filtering and the like is reduced, and the measurement precision of the system is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. High accuracy high voltage transformer collection system based on phase detection, it includes electronic current transformer, high pressure side signal processing circuit, optic fibre, low pressure side signal processing circuit and treater, its characterized in that: the low-voltage side signal processing circuit includes: the device comprises a photoelectric conversion module, an analog switch circuit, a band-pass filter, a low-pass filter, an automatic gain control circuit and a first A/D converter;
the electronic current transformer collects current signals on a bus and inputs the current signals into a high-voltage side signal processing circuit, the high-voltage side signal processing circuit processes, electro-optic converts and modulates the input current signals into optical signals, the optical signals are input to one end of an optical fiber, the optical signals are converted into voltage signals at the other end of the optical fiber through a photoelectric conversion module, the voltage signals are output to an analog switch circuit, the analog switch circuit compares the input voltage signals with a preset voltage amplitude value, when the input voltage signal amplitude value is larger than the preset voltage value, spike pulse signals are cut through a change-over switch, and the cut voltage signals are respectively input to a band-pass filter and a low-pass filter;
the band-pass filter filters a direct current component in a voltage signal output by the analog switch circuit, the filtered voltage signal is output to the automatic gain control circuit to be amplified, the amplified signal is sent to the first A/D converter to be subjected to analog-to-digital conversion, the converted digital signal is input to the first digital input end of the processor, and the processor obtains an alternating current component according to the digital signal;
the low-pass filter extracts a direct-current component in a voltage signal output by the analog switch circuit, inputs the direct-current component into the first A/D converter for analog-to-digital conversion, inputs a converted digital signal into the second digital input end of the processor, and the processor obtains the direct-current component according to the digital signal and divides the alternating-current component by the direct-current component to eliminate the influence of the direct-current component on the acquisition system.
2. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 1, wherein: the low-voltage side signal processing circuit also comprises a phase-shifting circuit;
the band-pass filter filters direct-current components in voltage signals output by the analog switch circuit, the filtered voltage signals are output to the phase-shifting circuit for phase compensation, and the voltage signals after phase compensation are input to the automatic gain control circuit for amplification.
3. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 1, wherein: the photoelectric conversion module comprises a photodiode, an I/V conversion circuit and an amplifying circuit;
and converting the optical signal into a photocurrent signal at the other end of the optical fiber through a photodiode, converting the photocurrent signal into a voltage signal through an I/V conversion circuit, and amplifying the voltage signal through an amplifying circuit and outputting the voltage signal to an analog switch circuit.
4. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 3, wherein: the analog switch circuit comprises a single-pole double-throw switch, a reference voltage circuit, a voltage comparator and a voltage follower;
the voltage signal output by the amplifying circuit is respectively input to the inverting input end of the voltage comparator and the input end of the voltage follower, the non-inverting input end of the voltage comparator is electrically connected with the reference voltage circuit, the output end of the voltage follower is electrically connected with the normally open contact of the single-pole double-throw switch, the normally closed contact of the single-pole double-throw switch is grounded, and the output end of the voltage comparator is electrically connected with the control end of the single-pole double-throw switch.
5. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 4, wherein: the reference voltage circuit includes: a resistor R11, a resistor R12 and a 5V power supply;
the 5V power supply is electrically connected with one end of the resistor R11 and the non-inverting input end of the voltage comparator through the resistor R12, and the other end of the resistor R11 is grounded.
6. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 4, wherein: the single pole double throw switch includes: a high-speed analog switch TS5a 3154;
the NC pin of the high-speed analog switch TS5A3154 is grounded, the NO pin is electrically connected with the output end of the voltage follower, and the IN pin of the high-speed analog switch TS5A3154 is electrically connected with the output end of the voltage comparator.
7. The phase detection-based high-precision high-voltage transformer acquisition system according to claim 1, wherein: the high-voltage side signal processing circuit includes: the device comprises an integrating amplifier, a bias circuit, a second A/D converter, a driving circuit and an electro-optical conversion module;
the integral amplifier integrates and amplifies current signals on a collecting bus of the electronic current transformer and outputs alternating current signals to the biasing circuit, the biasing circuit converts the alternating current signals into unipolar positive power supply signals and outputs the unipolar positive power supply signals to the second A/D converter for analog-to-digital conversion, and the output digital signals control the driving circuit to drive the electro-optical conversion module to convert the electric signals into optical signals and output the optical signals to one end of the optical fiber.
8. The phase detection-based high precision high voltage transformer acquisition system according to claim 7, wherein: the integrator comprises resistors R13-R17, a capacitor C4, a capacitor C5 and an operational amplifier TLV 2333;
the electronic current transformer is electrically connected with the inverting input end of an operational amplifier TLV2333 through a resistor R17, the non-inverting input end of the operational amplifier TLV2333 is grounded through a resistor R13, a capacitor C5 is electrically connected with the inverting input end and the output end of the operational amplifier TLV2333 in parallel, a resistor R14 and a resistor R15 are connected in series and then connected between the inverting input end and the output end of the operational amplifier TLV2333 in parallel, one end of a resistor R16 is electrically connected with the middle connection point of the resistor R14 and the resistor R15, and the other end of the resistor R16 is grounded through a capacitor C4.
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