CN112034407A - Power frequency alternating current voltage self-calibration unit and system - Google Patents
Power frequency alternating current voltage self-calibration unit and system Download PDFInfo
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Abstract
The application provides a power frequency alternating voltage self calibration unit and system, power frequency alternating voltage self calibration unit includes: the device comprises a voltage input module, a signal conditioning module and an AD conversion processing module; the voltage input module comprises a control switch, a first voltage reference and power frequency alternating current line input; a normally closed contact of the control switch is connected with the input of the power frequency alternating current circuit, a normally open contact of the control switch is connected with a first voltage reference, and a movable contact of the control switch is connected with the signal conditioning module; the signal conditioning module comprises a resistance voltage division circuit and anti-aliasing RC filtering, and is connected with the AD conversion processing module; the AD conversion processing module comprises a multi-path selection switch, a programmable gain amplifier, an analog-to-digital converter, a digital filter and a gain offset calibration register which are connected in sequence; the multi-path selection switch is connected with the signal conditioning module; the AD conversion processing module further comprises a second voltage reference connected with the analog-to-digital converter. The calibration precision of this application is high.
Description
Technical Field
The application relates to the technical field of voltage calibration, in particular to a power frequency alternating current voltage self-calibration unit and system.
Background
With the development of science and technology, electric energy is an indispensable resource for people. An electric power system is a carrier for transporting electric energy, and the quality of the electric energy in the electric power system needs to be detected in order to ensure the safety and stability of power utilization. In an electric power system, a voltage monitor is used for continuously measuring a power grid signal and storing, counting and analyzing voltage quality data, and is one of necessary means for monitoring and checking the voltage quality of the electric power system.
However, in the long-term operation process of the voltage monitor, the operation reliability and the measurement precision of the device are reduced due to aging, failure and interference of components, and the smooth and effective operation of the voltage quality monitoring work is further influenced. It is therefore an essential part to calibrate the voltage monitor regularly. In the prior art, the voltage monitor is generally calibrated once in three years, and is calibrated on site by workers.
However, the inventor analyzes that the installation environment of the voltage monitor is complex, the installation amount is large, the installation places are scattered, the difficulty of calibrating the precision of the voltage monitor by workers to the site is large, the calibration precision and efficiency are low, and the cost of manpower and material resources for manual calibration is high. Along with the development of an electric power system, the application range and the measurement precision of the voltage monitor are continuously improved, the calibration of the voltage monitor also has the requirements of more accuracy and low cost, and the prior art obviously does not meet the requirements.
Disclosure of Invention
The application provides a power frequency alternating current voltage self calibration unit and system to solve the problem that prior art calibration accuracy is low.
In order to solve the technical problem, the embodiment of the application discloses the following technical scheme:
in a first aspect, the present application provides a power frequency ac voltage self-calibration unit, including:
the device comprises a voltage input module, a signal conditioning module and an AD conversion processing module;
the voltage input module comprises a control switch, a first voltage reference and power frequency alternating current line input; the normally closed contact of the control switch is connected with the input of the power frequency alternating current circuit, the normally open contact of the control switch is connected with the first voltage reference, and the movable contact of the control switch is connected with the signal conditioning module and used for transmitting voltage to the signal conditioning module;
the signal conditioning module comprises a resistance voltage division circuit and anti-aliasing RC filtering, and is connected with the AD conversion processing module, and is used for conditioning the received voltage and sending the conditioned voltage to the AD conversion processing module;
the AD conversion processing module comprises a multi-path selection switch, a programmable gain amplifier, an analog-to-digital converter, a digital filter and a gain offset calibration register which are connected in sequence; the multi-path selection switch is connected with the signal conditioning module; the AD conversion processing module further comprises a second voltage reference connected with the analog-to-digital converter.
Optionally, the control switch is controlled by an external CPU;
when the power frequency alternating current voltage remote self-calibration unit works normally, the control switch is positioned on the normally closed contact, and the input of the power frequency alternating current line provides voltage; when the power frequency alternating current voltage remote self-calibration unit carries out remote self-calibration, the control switch is switched to a normally open contact, and voltage is provided by the first voltage reference.
Optionally, the resistance voltage-dividing circuit includes a first resistance and a second resistance;
one end of the first resistor is connected with the movable contact of the control switch, and the other end of the first resistor is connected with one end of the second resistor; the other end of the second resistor is grounded;
the anti-aliasing RC filter comprises a third resistor, a fourth resistor and a filter capacitor;
one end of the third resistor is connected with the other end of the first resistor, and the other end of the third resistor is respectively connected with the filter capacitor and the multi-path selection switch; one end of the fourth resistor is connected with the second resistor, and the other end of the fourth resistor is respectively connected with the other end of the filter capacitor and the multi-way selection switch.
Optionally, the multi-path selection switch is respectively connected to two ends of the filter capacitor, and is configured to respectively transmit an ac voltage signal and a dc voltage signal to the programmable gain amplifier;
the programmable gain amplifier is used for converting an alternating current signal into a direct current signal and respectively transmitting the alternating current signal and the direct current signal to the analog-to-digital converter;
the analog-to-digital converter is used for converting the analog voltage signal into digital data and inputting the digital data into the digital filter.
In a second aspect, the present application provides a single-phase power frequency ac voltage self-calibration system, including: the power frequency alternating current voltage self-calibration unit and the CPU control module are arranged in the circuit;
the CPU control module is connected with the gain offset calibration register, is used for receiving signals transmitted by the gain offset calibration register, and is used for controlling the control switch.
Optionally, the CPU control module includes:
the device comprises a CPU core control module, a wired communication module, a remote wireless communication module, a temperature measurement chip and a storage chip;
the wired communication module, the remote wireless communication module, the temperature measuring chip and the storage chip are respectively connected with the CPU core control module in a bidirectional way; and the wired communication module and the remote wireless communication module respectively perform data interaction with a master station.
In a third aspect, the present application provides a self-calibration system for three-phase power frequency ac voltage, including: four power frequency alternating current voltage self-calibration units and a CPU control module;
and the gain offset calibration registers of the power frequency alternating voltage remote self-calibration units are respectively connected with the CPU control module, and the analog-to-digital converters of the power frequency alternating voltage remote self-calibration units are mutually connected.
Optionally, the normally open contacts of the control switches of the power frequency alternating-current voltage self-calibration units are connected with each other, and share one first voltage reference; and each power frequency alternating current voltage self-calibration unit shares one second voltage reference.
Compared with the prior art, the beneficial effect of this application is:
the application provides a power frequency alternating voltage self calibration unit and system, and the self calibration unit includes: the device comprises a voltage input module, a signal conditioning module and an AD conversion processing module; the voltage input module comprises a control switch, a first voltage reference and power frequency alternating current line input; the normally closed contact of the control switch is connected with the input of the power frequency alternating current circuit, the normally open contact of the control switch is connected with a first voltage reference, and the movable contact of the control switch is connected with the signal conditioning module and used for transmitting voltage to the signal conditioning module; the signal conditioning module comprises a resistance voltage division circuit and anti-aliasing RC filtering, is connected with the AD conversion processing module, is used for conditioning the received voltage and sending the conditioned voltage to the AD conversion processing module; the AD conversion processing module comprises a multi-path selection switch, a programmable gain amplifier, an analog-to-digital converter, a digital filter and a gain offset calibration register which are connected in sequence; the multi-path selection switch is connected with the signal conditioning module; the AD conversion processing module further comprises a second voltage reference connected with the analog-to-digital converter. The self-calibration system also includes a CPU control module. The method and the device can perform self-calibration on the measurement errors generated in all the links of power frequency alternating current signal acquisition and processing, ensure the precision of long-time power frequency alternating current signal measurement, perform hardware self-check on all the links of power frequency alternating current signal acquisition and processing, and ensure the reliability of long-time power frequency alternating current signal measurement. The method and the device can avoid the condition that workers carry out calibration on site, save the cost of manpower and material resources, and improve the calibration efficiency and the reliability of system operation.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.
Fig. 1 is an overall schematic diagram of a power frequency ac voltage self-calibration unit and system provided in an embodiment of the present application;
FIG. 2 is a schematic diagram of a multi-way selector switch in an embodiment of the present application;
FIG. 3 is an overall schematic diagram of a single-phase power-frequency alternating-current voltage self-calibration system according to an embodiment of the present disclosure;
fig. 4 is an overall schematic diagram of a three-phase power frequency alternating-current voltage self-calibration system provided in the embodiment of the present application.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, an overall schematic diagram of a power frequency alternating-current voltage self-calibration unit provided in the embodiment of the present application is shown. As shown in fig. 1, the unit includes: the device comprises a voltage input module, a signal conditioning module and an AD conversion processing module.
The voltage input module includes a control switch S1, a first voltage reference, and a power frequency ac line input. Wherein the control switch S1 is divided into a normally closed contact 12, a normally open contact 14 and a moving contact 11. And a normally closed contact 12 of the control switch is connected with a power frequency alternating current circuit VA and is used for inputting power frequency alternating current voltage into the whole power frequency alternating current voltage self-calibration unit. The normally open contact 14 is connected with the first voltage reference A and is used for inputting the voltage provided by the first voltage reference A into the whole power frequency alternating current voltage self-calibration unit. The moving contact 11 is connected with the signal conditioning module and used for transmitting voltage to the signal conditioning module. Specifically, in fig. 1, VA is a live wire, and VN is a zero wire.
The signal conditioning module comprises a resistance voltage division circuit and anti-aliasing RC filtering. The signal conditioning module is connected with the AD conversion processing module, and is used for conditioning the received voltage and sending the conditioned voltage to the AD conversion processing module.
The AD conversion processing module comprises a multi-channel selection switch, a programmable gain amplifier, an analog-to-digital converter, a digital filter and a gain offset calibration register which are sequentially connected, and the multi-channel selection switch is connected with the signal conditioning module. The AD conversion processing module further comprises a second voltage reference B connected to the analog-to-digital converter.
In one embodiment of the present invention, control switch S1 is controlled by an external CPU.
When the whole power frequency alternating current voltage remote self-calibration unit normally works, the default is the voltage input of an external power frequency alternating current line, the control switch S1 is positioned on the normally closed contact 12, and the voltage is provided by the input of the power frequency alternating current line; when the power frequency alternating voltage remote self-calibration unit carries out remote self-calibration, the CPU switches the control switch S1 to the normally open contact 14, and the voltage is provided by the first voltage reference A.
Specifically, the internal reference a is a precise band-gap voltage reference with high stability, low temperature drift and relatively low cost, and is one of the key components of voltage self-calibration. After the precision band-gap voltage reference operates for 10 years, namely 87600 hours, the long-term voltage drift value is not more than 0.025 percent (250ppm), and the temperature drift is not more than 6 ppm/DEG C. And the contact switching voltage of the control switch S1 is not lower than 500VAC, and the contact resistance is lower than 100m omega when the control switch is closed.
In one embodiment of the present invention, the resistive voltage divider circuit includes a first resistor R1 and a second resistor R2.
One end of the first resistor R1 is connected to the moving contact 11 of the control switch S1, and the other end of R1 is connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to ground.
The anti-aliasing RC filter includes a third resistor R3, a fourth resistor R4, and a filter capacitor C1.
One end of the third resistor R3 is connected with the other end of the first resistor R1, and the other end of the R3 is respectively connected with the filter capacitor C1 and the multi-way selection switch. One end of the fourth resistor R4 is connected with the second resistor R2, and the other end of R4 is respectively connected with the other end of the filter capacitor C1 and the multi-way selection switch.
It should be noted that, in the embodiment of the present invention, a resistance voltage division manner is adopted for the external power frequency ac voltage or the internal reference voltage input, instead of the conventional low-power voltage converter manner. The linearity of the resistor voltage division mode sampling is better, so that the problem of poor linearity of a low-power voltage converter is avoided, and the long-term temperature drift resistance deviation of the divider resistor calibrated through a direct-current voltage reference is facilitated. The voltage is divided by the resistors R1 and R2, the externally input power frequency alternating voltage with the effective value of 1-456V can be converted into an alternating signal within the range of +/-1.2V, wherein the resistor R1 represents a single high-precision resistor or the total resistor formed by connecting a plurality of resistors in series. The anti-aliasing filtering adopts first-order passive RC filtering.
In one embodiment of the present invention, the multi-way selector switch is respectively connected to two ends of the filter capacitor C1, and can receive the ac voltage signal and the dc voltage signal at the same time. And respectively transmitting the alternating voltage signal and the direct voltage signal to the programmable gain amplifier.
The programmable gain amplifier in the embodiment of the invention adopts a 1-128 times programmable gain amplifier PGA, which is used for converting an alternating current signal into a direct current signal and respectively transmitting the alternating current signal and the direct current signal to the analog-to-digital converter.
The analog-to-digital converter adopts a sigma-delta type analog-to-digital converter with 24 bits and more for converting an analog voltage signal into digital data and inputting the digital data to the digital filter.
The second voltage reference B also adopts a precise band-gap voltage reference with high stability, low temperature drift and relatively low cost.
Fig. 2 is a schematic diagram of a multi-way selector switch according to an embodiment of the present invention.
The multi-path selection switch can respectively select and input the signal conditioning output voltage, the zero-volt voltage and the internal direct current self-checking voltage to the PGA and the sigma-delta type analog-digital converter. Specifically, the input and output of the PGA are short-circuited to obtain a zero-volt voltage for calibrating the zero-drift offset. When the multi-path selection register MUXn [1:0] is 00, the signal conditioning output voltage is used as input; when MUXn [1:0] is 01, zero volt voltage is used as input, the bias voltage of the AD conversion and processing circuit can be calibrated, and the bias adjustment value is stored in a gain bias calibration register and a storage chip; when MUXn [1:0] is 10, the internal direct current self-checking voltage and PGA are in the same phase as input; when MUXn [1:0] is equal to 11, the internal DC self-test voltage is inverted with respect to PGA as input. The AD conversion and processing circuit is self-checked by detecting whether the internal fixed direct-current voltage is correct or not.
Factors affecting the voltage measurement accuracy of the long-term alternating current signal include: long-term drift and temperature drift of voltage reference output voltage, long-term resistance drift and temperature drift of divider resistor, gain error and temperature drift of PGA, integral nonlinear error of sigma-delta type analog-to-digital converter, and offset error and offset temperature drift. In the embodiment of the invention, because a precise band gap voltage reference with high stability, low temperature drift and relatively low cost is adopted, the long-term drift and temperature drift influence of the voltage reference can be ignored, and the error influence on the measurement precision can also be ignored when the typical value of the full-scale input range integral nonlinear error of the sigma-delta type analog-to-digital converter is 7.5 ppm. In the long-term operation of the system, the proportional coefficient change caused by the resistance drift and the temperature drift of the divider resistor has large influence on the voltage measurement precision, and the voltage is calibrated in real time by switching to the voltage reference input through the switch during the remote self-calibration. The gain error of the PGA and the proportional error caused by the precision of the divider resistor are input into a high-precision rated alternating current voltage source for calibration through a production stage; the PGA gain temperature drift is slightly influenced by the external voltage reference, and the PGA gain temperature drift is compensated through the real-time temperature value of the temperature measuring chip according to the stored temperature curve. Calibration of the input offset error and offset temperature drift of a sigma-delta type analog-to-digital converter is achieved by setting the input to zero volts during a production phase and a remote self-calibration phase.
The embodiment of the invention also provides a single-phase power frequency alternating current voltage self-calibration system, and as shown in fig. 3, the single-phase power frequency alternating current voltage self-calibration system provided by the embodiment of the invention is an overall schematic diagram. The self-calibration system includes: the power frequency alternating current voltage self-calibration unit and the CPU control module.
The CPU control module is connected to the gain offset calibration register, and is configured to receive the signal transmitted by the gain offset calibration register and control the whole control switch S1.
In one embodiment of the invention, the CPU control module comprises: the device comprises a CPU core control module, a wired communication module, a remote wireless communication module, a temperature measurement chip and a storage chip.
The wired communication module comprises Ethernet and RS-485, and the remote wireless communication module comprises GPRS. The wired communication module, the remote wireless communication module, the temperature measurement chip and the storage chip are respectively in two-way connection with the CPU core control module, the storage chip is used for storing system calibration coefficients, and the temperature measurement chip is used for system temperature compensation.
The wired communication module and the remote wireless communication module are respectively in data interaction with a master station, and the master station conducts remote self-calibration on the system through remote wireless communication of GPRS, 4G modules and the like, and wired communication of Ethernet, RS-485 and the like.
In one embodiment of the invention, the process of calibrating the single-phase power frequency alternating voltage self-calibration system in the production stage is as follows:
in the production stage, firstly, the input of an analog-to-digital converter is set to be zero volt, and input offset calibration is carried out; then calibrating PGA gain error and divider resistance proportional error by external input high-precision power frequency rated AC voltage source, and calibrating the calibration coefficient a1Recording in a memory chip; then the CPU controls the switch of S1 to switch to the internal voltage reference A, the PGA gain is set to 64 or 128, and the average value Savg of the multiple sampling at the moment is obtained1And recording the real-time temperature value of the temperature measurement chip and other related parameters into the memory chip.
In one embodiment of the invention, the flow of the single-phase power frequency alternating-current voltage self-calibration system in the remote self-calibration process is as follows:
when a product runs for a period of time on site and a remote self-calibration command is executed, firstly, the input of an analog-to-digital converter is set to be zero volt, and input offset calibration is carried out; then the switch is switched to the internal voltage reference A by the CPU control S1, the PGA gain is set to 64 or 128, and the average Savg of the multiple sampling at this time is calculated2Recording the data into a memory chip; then, the temperature measurement chip carries out real-time temperature value compensation on the PGA gain temperature drift according to the stored temperature curve; finally according to Savg1And Savg2The variation of the specific coefficient, the temperature compensation, and the calibration coefficient a when the external input is the voltage of the power frequency AC line1And completing remote self-calibration and recording related parameters. When Savg appears1And Savg2When the deviation from the column coefficient is large, e.g. Savg2Relative Savg1If the deviation exceeds 3%, the hardware is judged to be abnormal, and the system feeds back the hardware abnormal alarm information to the host.
The embodiment of the invention also provides a three-phase power frequency alternating current voltage self-calibration system, and as shown in fig. 4, the system is an overall schematic diagram of the three-phase power frequency alternating current voltage self-calibration system provided by the embodiment of the invention. The system comprises: four power frequency alternating current voltage self-calibration units and a CPU control module.
The gain offset calibration registers of the power frequency alternating voltage remote self-calibration units are respectively connected with the CPU control module, and the analog-to-digital converters of the power frequency alternating voltage remote self-calibration units are mutually connected.
Specifically, the embodiment of the invention applies the A-phase voltage input signal processing circuit to the B-phase voltage and the C-phase voltage to obtain the three-phase power frequency alternating current voltage self-calibration system, and the A-phase voltage, the B-phase voltage, the C-phase voltage and the UX voltage are respectively converted into digital signals after being subjected to respective channel signal conditioning, AD conversion and processing and then are output to the CPU control module.
In one embodiment of the invention, the normally open contacts 14 of the control switches S1 of the power frequency ac voltage self-calibration units are connected to each other, and share a first voltage reference a; and each power frequency alternating current voltage self-calibration unit commonly uses a second voltage reference B.
In the embodiment of the invention, the UX voltage can be zero sequence voltage, and can also be other voltage signals such as voltage reference, temperature sensor output and the like.
Since the above embodiments are all described by referring to and combining with other embodiments, the same portions are provided between different embodiments, and the same and similar portions between the various embodiments in this specification may be referred to each other. And will not be described in detail herein.
In summary, compared with the prior art, the method has the following beneficial effects:
according to the embodiment of the application, the measurement errors generated in all the links of power frequency alternating current signal acquisition and processing can be self-calibrated, the precision of long-time power frequency alternating current signal measurement is guaranteed, meanwhile, hardware self-checking is carried out in all the links of power frequency alternating current signal acquisition and processing, and the reliability of long-time power frequency alternating current signal measurement is guaranteed. The method and the device can avoid the condition that workers carry out calibration on site, save the cost of manpower and material resources, and improve the calibration efficiency and the reliability of system operation.
It is noted that, in this specification, relational terms such as "first" and "second," and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such circuit structure, article, or apparatus. The term "comprising" a defined element does not, without further limitation, exclude the presence of other like elements in a circuit structure, article, or device that comprises the element.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims. The above-described embodiments of the present application do not limit the scope of the present application.
Claims (8)
1. A power frequency alternating current voltage self-calibration unit, comprising:
the device comprises a voltage input module, a signal conditioning module and an AD conversion processing module;
the voltage input module comprises a control switch, a first voltage reference and power frequency alternating current line input; the normally closed contact of the control switch is connected with the input of the power frequency alternating current circuit, the normally open contact of the control switch is connected with the first voltage reference, and the movable contact of the control switch is connected with the signal conditioning module and used for transmitting voltage to the signal conditioning module;
the signal conditioning module comprises a resistance voltage division circuit and anti-aliasing RC filtering, and is connected with the AD conversion processing module, and is used for conditioning the received voltage and sending the conditioned voltage to the AD conversion processing module;
the AD conversion processing module comprises a multi-path selection switch, a programmable gain amplifier, an analog-to-digital converter, a digital filter and a gain offset calibration register which are connected in sequence; the multi-path selection switch is connected with the signal conditioning module; the AD conversion processing module further comprises a second voltage reference connected with the analog-to-digital converter.
2. The self-calibration unit according to claim 1,
the control switch is controlled by an external CPU;
when the power frequency alternating current voltage remote self-calibration unit works normally, the control switch is positioned on the normally closed contact, and the input of the power frequency alternating current line provides voltage; when the power frequency alternating current voltage remote self-calibration unit carries out remote self-calibration, the control switch is switched to a normally open contact, and voltage is provided by the first voltage reference.
3. The self-calibration unit according to claim 1,
the resistance voltage division circuit comprises a first resistor and a second resistor;
one end of the first resistor is connected with the movable contact of the control switch, and the other end of the first resistor is connected with one end of the second resistor; the other end of the second resistor is grounded;
the anti-aliasing RC filter comprises a third resistor, a fourth resistor and a filter capacitor;
one end of the third resistor is connected with the other end of the first resistor, and the other end of the third resistor is respectively connected with the filter capacitor and the multi-path selection switch; one end of the fourth resistor is connected with the second resistor, and the other end of the fourth resistor is respectively connected with the other end of the filter capacitor and the multi-way selection switch.
4. The self-calibration unit according to claim 1,
the multi-path selection switch is respectively connected with two ends of the filter capacitor and is used for respectively transmitting an alternating current voltage signal and a direct current voltage signal to the programmable gain amplifier;
the programmable gain amplifier is used for converting an alternating current signal into a direct current signal and respectively transmitting the alternating current signal and the direct current signal to the analog-to-digital converter;
the analog-to-digital converter is used for converting the analog voltage signal into digital data and inputting the digital data into the digital filter.
5. A single-phase power frequency alternating voltage self-calibration system is characterized by comprising: the power frequency alternating current voltage self-calibration unit as claimed in any one of claims 1 to 4 and a CPU control module;
the CPU control module is connected with the gain offset calibration register, is used for receiving signals transmitted by the gain offset calibration register, and is used for controlling the control switch.
6. The self-calibration system of claim 5, wherein the CPU control module comprises:
the device comprises a CPU core control module, a wired communication module, a remote wireless communication module, a temperature measurement chip and a storage chip;
the wired communication module, the remote wireless communication module, the temperature measuring chip and the storage chip are respectively connected with the CPU core control module in a bidirectional way; and the wired communication module and the remote wireless communication module respectively perform data interaction with a master station.
7. A three-phase power frequency alternating voltage self-calibration system is characterized by comprising: four power frequency alternating current voltage self-calibration units according to any one of claims 1 to 4 and a CPU control module;
and the gain offset calibration registers of the power frequency alternating voltage remote self-calibration units are respectively connected with the CPU control module, and the analog-to-digital converters of the power frequency alternating voltage remote self-calibration units are mutually connected.
8. The self-calibration system of claim 7, wherein the normally open contacts of the control switches of the power frequency ac voltage self-calibration units are connected to each other, and share one first voltage reference; and each power frequency alternating current voltage self-calibration unit shares one second voltage reference.
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| CN112924915A (en) * | 2021-01-27 | 2021-06-08 | 云南电网有限责任公司电力科学研究院 | Mutual calibration system and method for voltage monitor |
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| US20140077980A1 (en) * | 2011-05-20 | 2014-03-20 | Abb Technology Ag | Arrangement for reading out an analogue voltage signal with self-calibration |
| CN105738848A (en) * | 2014-12-08 | 2016-07-06 | 华润矽威科技（上海）有限公司 | Self-calibration circuit and self-calibration method |
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| CN106597090A (en) * | 2017-01-23 | 2017-04-26 | 江苏中乂电气有限公司 | Electric energy data collection system based on wireless network transmission and working method thereof |
| CN113311373A (en) * | 2021-06-24 | 2021-08-27 | 广东电网有限责任公司 | Calibration method and calibration device for direct-current voltage transformer calibrator |
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| CN112924915A (en) * | 2021-01-27 | 2021-06-08 | 云南电网有限责任公司电力科学研究院 | Mutual calibration system and method for voltage monitor |
| CN112924915B (en) * | 2021-01-27 | 2023-11-21 | 云南电网有限责任公司电力科学研究院 | Mutual calibration system and method for voltage monitors |
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