A DC current transformer calibrator with a master-slave structure

Abstract

The present invention discloses a DC current transformer calibrator with a master-slave structure, which is characterized by comprising a DC current transformer calibrator host and a DC current transformer calibrator slave. The DC current transformer calibrator host includes a first power supply module, a first signal access module, a first synchronization module, a first control and processing module, a first wireless communication module and a first upper computer, which are respectively connected to the first power supply module. The DC current transformer calibrator slave includes a second power supply module, a second signal access module, a second synchronization module, a second control and processing module and a second wireless communication module, which are respectively connected to the second power supply module. The advantage is that it consists of two parts, namely the DC current transformer calibrator host and the DC current transformer calibrator slave. When the distance between the on-site standard DC current transformer and the DC current transformer to be tested is relatively far, the master-slave can be used in cooperation. After data interaction between the master and the slave through wireless, the current calibration error is displayed on the host.

Description

Technical Field

[0001] The present invention relates to a DC current transformer calibrator, and more particularly to a DC current transformer calibrator with a master-slave structure. Background Art

[0002] With the development of DC power transmission, especially flexible DC power transmission, DC current transformers are increasingly widely used. The need for DC current transformer calibration has become increasingly urgent. Especially after the localization and in-situ operation and maintenance management of DC current transformers, more and more manufacturers and grid provincial companies need to conduct tests on DC current transformers. As an important device for DC current transformer tests, DC current transformer calibrators have also been widely used. At present, there are various DC current transformer calibrators on the market, with both integral structures and split structures, but they are all used as a whole system and cannot be used separately, which has limitations at the test site. When the distance between the standard DC current transformer and the DC current transformer under test is relatively far, it is very inconvenient to use. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a DC current transformer calibrator with a master-slave structure that is less restricted by the test distance, which can directly test the performance of the DC current transformer under test that is relatively close to the standard DC current transformer on the host, and can also conveniently and quickly test the performance of the DC current transformer under test when the distance between the standard DC current transformer and the DC current transformer under test is relatively far.

[0004] The technical solution adopted by the present invention to solve the above technical problems is as follows: A DC current transformer calibrator with a master-slave structure includes a DC current transformer calibrator host and a DC current transformer calibrator slave. The DC current transformer calibrator host includes a first power supply module, a first signal access module, a first synchronization module, a first control and processing module, a first wireless communication module, and a first upper computer, which are respectively connected to the first power supply module. The DC current transformer calibrator slave includes a second power supply module, a second signal access module, a second synchronization module, a second control and processing module, and a second wireless communication module, which are respectively connected to the second power supply module. The first signal access module includes a first voltage division module, a shunt module, a second voltage division module, a first switching module, a first amplification module, a first differential amplification module, a second amplification module, a second differential amplification module, and a first AD conversion module. The first AD conversion module is provided with a first input terminal, a second input terminal, a third input terminal, and a fourth input terminal. The first voltage division module is used to receive the standard voltage signal output by the external standard DC voltage transformer, and then convert the received standard voltage signal into a first small voltage signal through voltage division and send it to the first input terminal of the first switching module. The shunt module is used to receive the standard current signal output by the external standard DC current transformer and convert it into a second small voltage signal and send it to the second input terminal of the first switching module. The second voltage division module is used to convert the voltage signal to be tested input externally into a third small voltage signal through voltage division and send it to the third input terminal of the first switching module. The first upper computer sends voltage detection instructions and current detection instructions to the first switching module through the first control and processing module. The first switching module connects the first input terminal according to the voltage detection instruction and sends the first small voltage signal to the input terminal of the first amplification module through the first output terminal, and at the same time connects the third input terminal and sends the third small voltage signal to the input terminal of the second amplification module through the second output terminal. The first switching module connects the second input terminal according to the current detection instruction and sends the received second small voltage signal to the input terminal of the first amplification module through the first output terminal, and at the same time connects the third input terminal and sends the received third small voltage signal to the input terminal of the second amplification module through the second output terminal. The positive output terminal of the first amplification module is connected to the positive input terminal of the first differential amplification module, and the negative output terminal of the first amplification module and the negative input terminal of the first differential amplification module are both grounded. The positive output terminal of the first differential amplification module is connected to the first input terminal of the first AD conversion module, and the negative output terminal of the first differential amplification module is connected to the second input terminal of the first AD conversion module. The positive output terminal of the second amplification module is connected to the positive input terminal of the second differential amplification module, and the negative output terminal of the second amplification module and the negative input terminal of the second differential amplification module are both grounded.The positive output terminal of the second differential amplification module is connected to the third input terminal of the first AD conversion module, and the negative output terminal of the second differential amplification module is connected to the fourth input terminal of the first AD conversion module. The first AD conversion module is connected to the first control and processing module through an SPI bus. The first control and processing module processes the received data to obtain the standard voltage effective value corresponding to the received first small voltage signal, the standard current effective value corresponding to the received second small voltage signal, and the first signal under test effective value corresponding to the received third small voltage signal;

[0005] The second signal access module includes a third voltage division module, a third amplification module, a third differential amplification module, and a second AD conversion module. The second AD conversion module is provided with a first input terminal and a second input terminal. The third voltage division module is used to convert the externally input signal under test voltage signal into a fourth small voltage signal through voltage division and send it to the input terminal of the third amplification module. The positive output terminal of the third amplification module is connected to the positive input terminal of the third differential amplification module, and the negative output terminal of the third amplification module and the negative input terminal of the third differential amplification module are both grounded. The positive output terminal of the third differential amplification module is connected to the first input terminal of the second AD conversion module, and the negative output terminal of the third differential amplification module is connected to the second input terminal of the second AD conversion module. The second AD conversion module is connected to the second control and processing module through an SPI bus. The second control and processing module processes the received data to obtain the second signal under test effective value corresponding to the fourth small voltage signal and sends it to the second wireless communication module. The second wireless communication module sends the second signal under test effective value to the first control and processing module through the first wireless communication module;

[0006] The first control and processing module compares the standard voltage effective value with the first signal under test effective value to obtain a first voltage comparison result when detecting the DC voltage transformer under test, compares the standard voltage effective value with the received second signal under test effective value to obtain a second voltage comparison result, compares the standard current effective value with the first signal under test effective value to obtain a first current comparison result when detecting the DC current transformer under test, compares the standard current effective value with the received second signal under test effective value to obtain a second current comparison result, and finally sends the obtained first voltage comparison result or first current comparison result or second voltage comparison result or second current comparison result to the first host computer. The first host computer stores the received data and displays the corresponding detection result. The first synchronization module is used to send a first synchronization signal to the first control and processing module, and the second synchronization module is used to send a second synchronization signal that is consistent with the first synchronization signal in time to the second control and processing module.

[0007] The structures of the first amplification module, the second amplification module, and the third amplification module are the same. The first amplification module includes a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a programmable gain amplifier of model PGA204. One end of the first resistor is grounded, and the other end of the first resistor, one end of the first capacitor, and the 4th pin of the programmable gain amplifier are connected. One end of the second resistor is connected to the first output end of the first switching module, and the other end of the second resistor, one end of the second capacitor, and the 5th pin of the programmable gain amplifier are connected. The 8th pin of the programmable gain amplifier, one end of the third capacitor, and the -15V voltage output end of the first power supply module are connected. The 13th pin of the programmable gain amplifier, one end of the fourth capacitor, and the +15V voltage output end of the first power supply module are connected. The 11th pin, the 12th pin of the programmable gain amplifier, and the positive input end of the first differential amplification module are connected. The other ends of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the 10th pin of the programmable gain amplifier, and the 14th pin of the programmable gain amplifier are all grounded.

[0008] The structures of the first differential amplification module, the second differential amplification module, and the third differential amplification module are the same. The first differential amplification module includes a fully differential amplifier of model OPA1632, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. One end of the third resistor is connected to the positive output terminal of the first amplification module, and the other end of the third resistor, the 8th pin of the fully differential amplifier, one end of the fifth resistor, and one end of the sixth capacitor are connected. One end of the fourth resistor is grounded, and the other end of the fourth resistor, the 1st pin of the fully differential amplifier, one end of the seventh capacitor, and one end of the eighth resistor are connected. The 3rd pin of the fully differential amplifier, one end of the fifth capacitor, and the +15V voltage output terminal of the first power supply module are connected. The 6th pin of the fully differential amplifier, one end of the eighth capacitor, and the -15V voltage output terminal of the first power supply module are connected. The other end of the sixth capacitor, the 5th pin of the fully differential amplifier, and one end of the sixth resistor are connected. The other end of the fifth resistor, the other end of the sixth resistor, one end of the ninth capacitor, and the second input terminal of the first AD conversion module are connected. The 4th pin of the fully differential amplifier, the other end of the seventh capacitor, and one end of the seventh resistor are connected. The other end of the seventh resistor, the other end of the eighth resistor, the other end of the ninth capacitor, and the first input terminal of the first AD conversion module are connected. The other ends of the fifth capacitor and the eighth capacitor are respectively grounded.

[0009] The DC current transformer calibrator host also includes a first self-calibration module connected to the first power supply module. The first self-calibration module is used to send a first reference self-calibration signal to the fourth input terminal of the first switching module. The first upper computer sends a first self-calibration instruction and a second self-calibration instruction to the first switching module respectively through the first control processing module. The first switching module connects the fourth input terminal according to the first self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the first amplification module through the first output terminal. The first switching module connects the fourth input terminal according to the second self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the second amplification module through the second output terminal. The DC current transformer calibrator host has a built-in self-calibration system, and self-calibration is performed after the device is preheated, which can ensure that the DC current transformer calibrator host has good calibration accuracy in different environments.

[0010] The slave unit of the DC current transformer calibrator further includes a second host computer, a second self-calibration module, and a second switching module respectively connected to the second power supply module. The third voltage dividing module is used to send a fourth small voltage signal to the first input end of the second switching module. The second self-calibration module is used to send a second reference self-calibration signal to the second input end of the second switching module. The second host computer respectively sends a slave unit signal detection instruction and a third self-calibration instruction to the second switching module through the second control and processing module. The second switching module connects the first input end according to the slave unit signal detection instruction and sends the fourth small voltage signal to the input end of the third amplification module through the output end. The second switching module connects the second input end according to the third self-calibration instruction and sends the second reference self-calibration signal to the input end of the third amplification module through the output end. The slave unit of the DC current transformer calibrator is internally equipped with a self-calibration system. By switching between the signal detection and self-calibration working modes through the second switching module and performing self-calibration after the device is preheated, it can ensure that the slave unit of the DC current transformer calibrator has good calibration accuracy in different environments. The second host computer can also synchronously display the error detection results of the DC current transformer to be tested with the first host computer.

[0011] Compared with the prior art, the advantages of the present invention are as follows: It includes two parts, namely the main unit of the DC current transformer calibrator and the slave unit of the DC current transformer calibrator. The main unit of the DC current transformer calibrator and the slave unit of the DC current transformer calibrator use wireless communication. The main unit of the DC current transformer calibrator can simultaneously receive the signals output by the standard DC current transformer and the DC current transformer to be tested, and independently complete the accuracy calibration of the DC current transformer. The slave unit of the DC current transformer calibrator is a portable mobile device, and the second power supply module is powered by a battery. When the standard DC current transformer and the DC current transformer to be tested are far apart on-site, the master-slave units can be used in combination. The master unit receives the signal output by the standard DC current transformer, and the slave unit receives the output signal of the DC current transformer to be tested. After data interaction between the master and slave units through wireless, the current calibration error is displayed on the master unit. Among them, the first synchronization module and the second synchronization module have optical synchronization signal interfaces and electrical synchronization signal interfaces, and can receive and send synchronization signals conforming to the forms of PPS and IRIG-B codes, which are used to ensure the temporal consistency of the data received by the master and slave units. Each small voltage signal in the present invention refers to a voltage signal below 10V. The voltage signal to be tested input externally is generated by the signal detection circuit of a conventional DC voltage transformer to be tested or a DC current transformer to be tested.

[0012] The present invention mainly aims at the error calibration of DC current transformers in intelligent substations, and can perform error calibration on DC voltage transformers and DC current transformers. It can also be extended to perform error calibration on electronic DC voltage transformers and electronic DC current transformers, as well as common functions such as automatically reading the readings of high-precision multimeters through interfaces. Through practical applications in actual scenarios, it has been proven that the master-slave separation structure of the present invention provides many conveniences for on-site testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the overall structural block diagram of Embodiment 1;

[0014] Figure 2 It is the overall structural block diagram of Embodiment 2;

[0015] Figure 3 It is the circuit structure diagram of the first amplification module in Embodiment 1;

[0016] Figure 4 It is the circuit structure diagram of the first differential amplification module in Embodiment 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] Embodiment 1: A DC current transformer calibrator with a master-slave structure, comprising a DC current transformer calibrator host and a DC current transformer calibrator slave. The DC current transformer calibrator host includes a first power supply module (not shown in the figure) and a first signal access module, a first synchronization module 11, a first control and processing module 12, a first wireless communication module 13, and a first upper computer 14, which are respectively connected to the first power supply module. The DC current transformer calibrator slave includes a second power supply module (not shown in the figure) and a second signal access module, a second synchronization module 21, a second control and processing module 22, and a second wireless communication module 23, which are respectively connected to the second power supply module. The first signal access module includes a first voltage division module 31, a shunt module 32, a second voltage division module 33, a first switching module 34, a first amplification module 35, a first differential amplification module 36, a second amplification module 37, a second differential amplification module 38, and a first AD conversion module 39. The first AD conversion module 39 is provided with a first input terminal, a second input terminal, a third input terminal, and a fourth input terminal. The first voltage division module 31 is used to receive the standard voltage signal output by the external standard DC voltage transformer, and then convert the received standard voltage signal into a first small voltage signal through voltage division and send it to the first input terminal of the first switching module 34. The shunt module 32 is used to receive the standard current signal output by the external standard DC current transformer and convert it into a second small voltage signal and send it to the second input terminal of the first switching module 34. The second voltage division module 33 is used to convert the voltage signal to be tested input externally into a third small voltage signal through voltage division and send it to the third input terminal of the first switching module 34. The first upper computer 14 sends voltage detection instructions and current detection instructions to the first switching module 34 through the first control and processing module 12. The first switching module 34 connects the first input terminal according to the voltage detection instruction and sends the received first small voltage signal to the input terminal of the first amplification module 35 through the first output terminal, and at the same time connects the third input terminal and sends the received third small voltage signal to the input terminal of the second amplification module 37 through the second output terminal. The first switching module 34 connects the second input terminal according to the current detection instruction and sends the received second small voltage signal to the input terminal of the first amplification module 35 through the first output terminal, and at the same time connects the third input terminal and sends the received third small voltage signal to the input terminal of the second amplification module 37 through the second output terminal. The positive output terminal of the first amplification module 35 is connected to the positive input terminal of the first differential amplification module 36, and the negative output terminal of the first amplification module 35 and the negative input terminal of the first differential amplification module 36 are both grounded. The positive output terminal of the first differential amplification module 36 is connected to the first input terminal of the first AD conversion module 39, and the negative output terminal of the first differential amplification module 36 is connected to the second input terminal of the first AD conversion module 39. The positive output terminal of the second amplification module 37 is connected to the positive input terminal of the second differential amplification module 38, and the negative output terminal of the second amplification module 37 and the negative input terminal of the second differential amplification module 38 are both grounded.The positive output terminal of the second differential amplification module 38 is connected to the third input terminal of the first AD conversion module 39, and the negative output terminal of the second differential amplification module 38 is connected to the fourth input terminal of the first AD conversion module 39. The first AD conversion module 39 is connected to the first control and processing module 12 through the SPI bus. The first control and processing module 12 processes the received data to obtain the effective value of the standard voltage corresponding to the received first small voltage signal, the effective value of the standard current corresponding to the received second small voltage signal, and the effective value of the first signal under test corresponding to the received third small voltage signal;

[0019] The second signal access module includes a third voltage division module 41, a third amplification module 42, a third differential amplification module 43, and a second AD conversion module 44. The second AD conversion module 44 is provided with a first input terminal and a second input terminal. The third voltage division module 41 is used to convert the externally input signal voltage under test into a fourth small voltage signal through voltage division and send it to the input terminal of the third amplification module 42. The positive output terminal of the third amplification module 42 is connected to the positive input terminal of the third differential amplification module 43, and the negative output terminal of the third amplification module 42 and the negative input terminal of the third differential amplification module 43 are both grounded. The positive output terminal of the third differential amplification module 43 is connected to the first input terminal of the second AD conversion module 44, and the negative output terminal of the third differential amplification module 43 is connected to the second input terminal of the second AD conversion module 44. The second AD conversion module 44 is connected to the second control and processing module 22 through the SPI bus. The second control and processing module 22 processes the received data to obtain the effective value of the second signal under test corresponding to the fourth small voltage signal and sends it to the second wireless communication module 23. The second wireless communication module 23 sends the effective value of the second signal under test to the first control and processing module 12 through the first wireless communication module 13;

[0020] When detecting the DC voltage transformer under test, the first control and processing module 12 compares the effective value of the standard voltage with the effective value of the first signal under test to obtain the first voltage comparison result, compares the effective value of the standard voltage with the effective value of the second signal under test received to obtain the second voltage comparison result. When detecting the DC current transformer under test, it compares the effective value of the standard current with the effective value of the first signal under test to obtain the first current comparison result, compares the effective value of the standard current with the effective value of the second signal under test received to obtain the second current comparison result. Finally, it sends the obtained first voltage comparison result or first current comparison result or second voltage comparison result or second current comparison result to the first host computer 14. The first host computer 14 stores the received data and displays the corresponding detection results. The first synchronization module 11 is used to send the first synchronization signal to the first control and processing module 12, and the second synchronization module 21 is used to send the second synchronization signal that is consistent with the first synchronization signal in time to the second control and processing module 22;

[0021] The structures of the first amplification module 35, the second amplification module 37, and the third amplification module 42 are the same. The first amplification module 35 includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a programmable gain amplifier U1 of model PGA204. One end of the first resistor R1 is grounded, and the other end of the first resistor R1, one end of the first capacitor C1, and the 4th pin of the programmable gain amplifier U1 are connected. One end of the second resistor R2 is connected to the first output end of the first switching module 34, and the other end of the second resistor R2, one end of the second capacitor C2, and the 5th pin of the programmable gain amplifier U1 are connected. The 8th pin of the programmable gain amplifier U1, one end of the third capacitor C3, and the -15V voltage output end of the first power supply module are connected. The 13th pin of the programmable gain amplifier U1, one end of the fourth capacitor C4, and the +15V voltage output end of the first power supply module are connected. The 11th pin, the 12th pin of the programmable gain amplifier U1, and the positive input end of the first differential amplification module 36 are connected. The other ends of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, the 10th pin of the programmable gain amplifier U1, and the 14th pin of the programmable gain amplifier U1 are all grounded;

[0022] The structures of the first differential amplification module 36, the second differential amplification module 38, and the third differential amplification module 43 are the same. The first differential amplification module 36 includes a fully differential amplifier U2 of model OPA1632, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, and a ninth capacitor C9. One end of the third resistor R3 is connected to the positive output terminal of the first amplification module 35, and the other end of the third resistor R3, the 8th pin of the fully differential amplifier U2, one end of the fifth resistor R5, and one end of the sixth capacitor C6 are connected. One end of the fourth resistor R4 is grounded, and the other end of the fourth resistor R4, the 1st pin of the fully differential amplifier U2, one end of the seventh capacitor C7, and one end of the eighth resistor R8 are connected. The 3rd pin of the fully differential amplifier U2, one end of the fifth capacitor C5, and the +15V voltage output terminal of the first power supply module are connected. The 6th pin of the fully differential amplifier U2, one end of the eighth capacitor C8, and the -15V voltage output terminal of the first power supply module are connected. The other end of the sixth capacitor C6, the 5th pin of the fully differential amplifier U2, and one end of the sixth resistor R6 are connected. The other end of the fifth resistor R5, the other end of the sixth resistor R6, one end of the ninth capacitor C9, and the second input terminal of the first AD conversion module 39 are connected. The 4th pin of the fully differential amplifier U2, the other end of the seventh capacitor C7, and one end of the seventh resistor R7 are connected. The other end of the seventh resistor R7, the other end of the eighth resistor R8, the other end of the ninth capacitor C9, and the first input terminal of the first AD conversion module 39 are connected. The other ends of the fifth capacitor C5 and the eighth capacitor C8 are respectively grounded.

[0023] In the first embodiment, each voltage division module adopts a voltage division circuit with high input impedance composed of resistor voltage division and operational amplifier follower, which is used to perform a certain proportion of voltage division on the voltage signal output by the standard DC voltage transformer or the DC voltage transformer under test to obtain a corresponding small voltage signal. The shunt module adopts a current-to-small voltage circuit composed of a high-precision sampling resistor and an operational amplifier to convert the current signal output by the standard current transformer and output a small voltage signal proportional to it.

[0024] The first switching module adopts a switching circuit composed of a relay with low contact impedance and fast response as the core device, and performs line switching according to the received configuration instruction to connect and output the voltage signal to be processed.

[0025] AD conversion module: Adopts a wide-bandwidth and high-precision 24-bit ADC chip as the core device, and cooperates with auxiliary circuits such as an amplification module and a differential amplification module to form a high-precision analog-to-digital conversion circuit. Samples the received small voltage signal and converts it into a digital signal through the SPI bus and outputs it to the corresponding control and processing module.

[0026] The control processing module includes an FPGA module and an ARM module. The FPGA module uses a high-performance FPGA chip from Intel Corporation. The AD module controller, synchronization module controller, etc. are generated in the FPGA using a hardware description language. It is used to control the working states of each module and information interaction, preprocess the data of each module, and then perform data interaction with the ARM module through a parallel bus. The ARM module uses an ARM chip from STMicroelectronics, performs data interaction with the FPGA module through the parallel bus FSMC, and performs data interaction with the wireless communication module through a serial port. It performs arithmetic processing on the data according to the instructions from the host computer and outputs the arithmetic results to the host computer and the wireless communication module.

[0027] The synchronization module uses a high-sensitivity laser receiver from AVAGO to receive the optical synchronization signal, a high-power laser transmitter to output the optical synchronization signal, and an aviation socket to receive and send the point synchronization signal. The synchronization signal conforms to the PPS and IRIG-B code formats.

[0028] The wireless communication module can use the KYL-1020L low-power wireless data transmission module. The first host computer uses the Windows operating system and is used for human-computer interaction and data interaction with the ARM module.

[0029] Embodiment 2: The rest is the same as Embodiment 1, except that the DC current transformer calibrator host further includes a first self-calibration module 5 connected to the first power module. The first self-calibration module 5 is used to send a first reference self-calibration signal to the fourth input terminal of the first switching module 34. The first host computer 14 sends a first self-calibration instruction and a second self-calibration instruction to the first switching module 34 through the first control processing module 12. The first switching module 34 connects the fourth input terminal according to the first self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the first amplification module 35 through the first output terminal. The first switching module 34 connects the fourth input terminal according to the second self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the second amplification module 37 through the second output terminal.

[0030] The slave unit of the DC current transformer calibrator further includes a second host computer 61, a second self-calibration module 62, and a second switching module 63 that are respectively connected to the second power supply module. The third voltage dividing module 41 is used to send a fourth small voltage signal to the first input end of the second switching module 63. The second self-calibration module 62 is used to send a second reference self-calibration signal to the second input end of the second switching module 63. The second host computer 61 respectively sends a slave unit signal detection instruction and a third self-calibration instruction to the second switching module 63 through the second control processing module 22. The second switching module 63 connects the first input end according to the slave unit signal detection instruction and sends the fourth small voltage signal to the input end of the third amplification module 42 through the output end. The second switching module 63 connects the second input end according to the third self-calibration instruction and sends the second reference self-calibration signal to the input end of the third amplification module 42 through the output end.

[0031] In the second embodiment, the self-calibration module uses a reference circuit composed of a high-precision reference chip and a precision operational amplifier with a high input impedance as the core, and can receive an external reference signal and output the external reference signal and the internal reference signal to the corresponding switching module at the same time.

Claims

1. A DC current transformer calibrator with a master-slave structure, characterized in that It includes a main unit of a DC current transformer calibrator and a slave unit of a DC current transformer calibrator. The main unit of the DC current transformer calibrator includes a first power supply module, a first signal access module, a first synchronization module, a first control and processing module, a first wireless communication module, and a first host computer, which are respectively connected to the first power supply module. The slave unit of the DC current transformer calibrator includes a second power supply module, a second signal access module, a second synchronization module, a second control and processing module, and a second wireless communication module, which are respectively connected to the second power supply module. The first signal access module includes a first voltage division module, a shunt module, a second voltage division module, a first switching module, a first amplification module, a first differential amplification module, a second amplification module, a second differential amplification module, and a first AD conversion module. The first AD conversion module is provided with a first input terminal, a second input terminal, a third input terminal, and a fourth input terminal. The first voltage division module is used to receive the standard voltage signal output by an external standard DC voltage transformer, and then convert the received standard voltage signal into a first small voltage signal through voltage division and send it to the first input terminal of the first switching module. The shunt module is used to receive the standard current signal output by an external standard DC current transformer and convert it into a second small voltage signal and send it to the second input terminal of the first switching module. The second voltage division module is used to convert the voltage signal to be tested input externally into a third small voltage signal through voltage division and send it to the third input terminal of the first switching module. The first host computer sends voltage detection instructions and current detection instructions to the first switching module through the first control and processing module. The first switching module connects the first input terminal according to the voltage detection instruction and sends the first small voltage signal to the input terminal of the first amplification module through the first output terminal, and at the same time connects the third input terminal and sends the third small voltage signal to the input terminal of the second amplification module through the second output terminal. The first switching module connects the second input terminal according to the current detection instruction and sends the received second small voltage signal to the input terminal of the first amplification module through the first output terminal, and at the same time connects the third input terminal and sends the received third small voltage signal to the input terminal of the second amplification module through the second output terminal. The positive output terminal of the first amplification module is connected to the positive input terminal of the first differential amplification module. The negative output terminal of the first amplification module and the negative input terminal of the first differential amplification module are both grounded. The positive output terminal of the first differential amplification module is connected to the first input terminal of the first AD conversion module. The negative output terminal of the first differential amplification module is connected to the second input terminal of the first AD conversion module. The positive output terminal of the second amplification module is connected to the positive input terminal of the second differential amplification module. The negative output terminal of the second amplification module and the negative input terminal of the second differential amplification module are both grounded. The positive output terminal of the second differential amplification module is connected to the third input terminal of the first AD conversion module,The negative output terminal of the second differential amplification module is connected to the fourth input terminal of the first AD conversion module. The first AD conversion module is connected to the first control and processing module through an SPI bus. The first control and processing module processes the received data to obtain the standard voltage effective value corresponding to the received first small voltage signal, the standard current effective value corresponding to the received second small voltage signal, and the first detected signal effective value corresponding to the received third small voltage signal; The second signal access module described above includes a third voltage division module, a third amplification module, a third differential amplification module, and a second AD conversion module. The second AD conversion module is provided with a first input end and a second input end. The third voltage division module is used to convert the externally input voltage signal to be detected into a fourth small voltage signal through voltage division and send it to the input end of the third amplification module. The positive output end of the third amplification module is connected to the positive input end of the third differential amplification module. The negative output end of the third amplification module and the negative input end of the third differential amplification module are both grounded. The positive output end of the third differential amplification module is connected to the first input end of the second AD conversion module. The negative output end of the third differential amplification module is connected to the second input end of the second AD conversion module. The second AD conversion module is connected to the second control processing module through the SPI bus. The second control processing module processes the received data to obtain the effective value of the second signal to be detected corresponding to the fourth small voltage signal and sends it to the second wireless communication module. The second wireless communication module sends the effective value of the second signal to be detected to the first control processing module through the first wireless communication module; When detecting the DC voltage transformer under test, the first control processing module compares the standard voltage effective value with the effective value of the first signal to be detected to obtain a first voltage comparison result, compares the standard voltage effective value with the received effective value of the second signal to be detected to obtain a second voltage comparison result. When detecting the DC current transformer under test, it compares the standard current effective value with the effective value of the first signal to be detected to obtain a first current comparison result, compares the standard current effective value with the received effective value of the second signal to be detected to obtain a second current comparison result. Finally, it sends the obtained first voltage comparison result or first current comparison result or second voltage comparison result or second current comparison result to the first host computer. The first host computer stores the received data and displays the corresponding detection results. The first synchronization module is used to send a first synchronization signal to the first control processing module. The second synchronization module is used to send a second synchronization signal that is consistent with the first synchronization signal in time to the second control processing module. The first synchronization module and the second synchronization module have optical synchronization signal interfaces and electrical synchronization signal interfaces, and receive and send synchronization signals in the form of PPS and IRIG-B codes through the optical synchronization signal interfaces and the electrical synchronization signal interfaces to ensure the temporal consistency of the data received by the main unit and the slave unit of the DC transformer calibrator.

2. The DC current transformer calibrator with a master-slave structure according to claim 1, characterized in that The structures of the first amplification module, the second amplification module, and the third amplification module are the same. The first amplification module includes a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a programmable gain amplifier of model PGA204. One end of the first resistor is grounded, and the other end of the first resistor, one end of the first capacitor, and the 4th pin of the programmable gain amplifier are connected. One end of the second resistor is connected to the first output end of the first switching module, and the other end of the second resistor, one end of the second capacitor, and the 5th pin of the programmable gain amplifier are connected. The 8th pin of the programmable gain amplifier, one end of the third capacitor, and the -15V voltage output end of the first power supply module are connected. The 13th pin of the programmable gain amplifier, one end of the fourth capacitor, and the +15V voltage output end of the first power supply module are connected. The 11th pin, the 12th pin of the programmable gain amplifier, and the positive input end of the first differential amplification module are connected. The other ends of the first capacitor, the second capacitor, the third capacitor, the fourth capacitor, the 10th pin of the programmable gain amplifier, and the 14th pin of the programmable gain amplifier are all grounded.

3. The DC current transformer calibrator with a master-slave structure according to claim 1, characterized in that The structures of the first differential amplification module, the second differential amplification module, and the third differential amplification module are the same. The first differential amplification module includes a fully differential amplifier of model OPA1632, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, and a ninth capacitor. One end of the third resistor is connected to the positive output terminal of the first amplification module. The other end of the third resistor, the 8th pin of the fully differential amplifier, one end of the fifth resistor, and one end of the sixth capacitor are connected. One end of the fourth resistor is grounded. The other end of the fourth resistor, the 1st pin of the fully differential amplifier, one end of the seventh capacitor, and one end of the eighth resistor are connected. The 3rd pin of the fully differential amplifier, one end of the fifth capacitor, and the +15V voltage output terminal of the first power supply module are connected. The 6th pin of the fully differential amplifier, one end of the eighth capacitor, and the -15V voltage output terminal of the first power supply module are connected. The other end of the sixth capacitor, the 5th pin of the fully differential amplifier, and one end of the sixth resistor are connected. The other end of the fifth resistor, the other end of the sixth resistor, one end of the ninth capacitor, and the second input terminal of the first AD conversion module are connected. The 4th pin of the fully differential amplifier, the other end of the seventh capacitor, and one end of the seventh resistor are connected. The other end of the seventh resistor, the other end of the eighth resistor, the other end of the ninth capacitor, and the first input terminal of the first AD conversion module are connected. The other ends of the fifth capacitor and the eighth capacitor are respectively grounded.

4. The DC current transformer calibrator with a master-slave structure according to claim 1, characterized in that The DC current transformer calibrator host further includes a first self-calibration module connected to the first power supply module. The first self-calibration module is used to send a first reference self-calibration signal to the fourth input terminal of the first switching module. The first upper computer sends a first self-calibration instruction and a second self-calibration instruction to the first switching module respectively through the first control processing module. The first switching module connects the fourth input terminal according to the first self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the first amplification module through the first output terminal. The first switching module connects the fourth input terminal according to the second self-calibration instruction and sends the first reference self-calibration signal to the input terminal of the second amplification module through the second output terminal.

5. A DC current transformer calibrator with a master-slave structure according to claim 1, characterized in that The slave DC current transformer calibrator further includes a second host computer, a second self-calibration module, and a second switching module respectively connected to the second power supply module. The third voltage division module is configured to send a fourth small voltage signal to a first input end of the second switching module. The second self-calibration module is configured to send a second reference self-calibration signal to a second input end of the second switching module. The second host computer respectively sends a slave signal detection instruction and a third self-calibration instruction to the second switching module through the second control and processing module. The second switching module connects the first input end according to the slave signal detection instruction and sends the fourth small voltage signal to an input end of the third amplification module through the output end. The second switching module connects the second input end according to the third self-calibration instruction and sends the second reference self-calibration signal to the input end of the third amplification module through the output end.

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