Fieldbus pressure transmitter calibration system and method

Abstract

The application discloses a field bus pressure transmitter calibration system and method in the technical field of pressure transmitter, which comprises a control host computer, a resistance acquisition module, a current calculation module, an error acquisition module and a resistance substitution module connected with the control host computer, the error acquisition module comprises a first pressure conversion unit and a second pressure conversion unit; the resistance acquisition module is used for acquiring the resistance value of the internal sensor after deformation under the action of external pressure; the current calculation module is used for acquiring the current according to the resistance value; the error acquisition module is used for obtaining the error by subtracting the local external pressure displayed by the first pressure conversion unit from the remote external pressure displayed by the system bus and the second pressure conversion unit; and the resistance substitution module is used for substituting the resistance value of the internal sensor after deformation by the resistance set when the error exceeds the maximum allowable error range of the pressure transmitter, so as to provide the zero point reference, the intermediate value reference and the full scale reference for the pressure transmitter to realize the calibration of the identification program of the pressure transmitter. The application can solve the technical problem of the decline of the measurement accuracy of the bus pressure transmitter caused by the vibration, impact and electromagnetic interference and other factors generated by the equipment operation.

Description

Technical Field

[0001] This invention relates to the field of pressure transmitter technology, and more particularly to a fieldbus pressure transmitter calibration system and method. Background Technology

[0002] Currently, fieldbus pressure transmitters are widely used in the production and operation of thermal power plants. The main function of the fieldbus pressure transmitter is to convert pressure parameters in power production, such as differential pressure, absolute pressure, and gauge pressure, into fieldbus digital signals and transmit them to the control master station. This provides early warning, data analysis, and control for safe power production, and the fieldbus pressure transmitter provides technical assurance for the safe operation of thermal power plants.

[0003] However, the operation of equipment in thermal power plants currently generates vibrations, shocks, and electromagnetic interference, which can lead to a decrease in the measurement accuracy of bus pressure transmitters and affect their signal transmission. Therefore, it is necessary to calibrate the pressure transmitters. However, existing calibration methods all require removing the bus pressure transmitters from the complex operating environment of thermal power plants. Frequent disassembly and installation can affect the service life of the pressure transmitters, and the disassembly and installation process also poses potential risks and safety issues. In summary, in order to ensure the accuracy and reliability of bus pressure transmitters, this paper proposes a field bus pressure transmitter calibration system and method, providing technical support for the safe and stable operation of the equipment. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fieldbus pressure transmitter calibration system and method that can solve the technical problem of decreased measurement accuracy of the fieldbus pressure transmitter caused by factors such as vibration, shock and electromagnetic interference generated during equipment operation.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a fieldbus pressure transmitter calibration system, including a control host and a resistance acquisition module, a current calculation module, an error acquisition module and a resistance substitution module connected to the control host by signal. The error acquisition module includes a first pressure conversion unit and a second pressure conversion unit. The resistance acquisition module is used to acquire the resistance value of the pressure transmitter after the internal sensor deforms under external pressure. The current calculation module is used to obtain the current based on the resistance value; The error acquisition module is used to obtain the error by subtracting the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit. The resistor substitution module is used to replace the deformation resistance value generated by the internal sensor with a resistor set when the error exceeds the maximum permissible error range of the pressure transmitter, so as to provide the pressure transmitter with a zero-point reference, an intermediate value reference and a full-scale reference to achieve calibration of the pressure transmitter identification program.

[0006] Furthermore, it also includes a signal processing module, an A / D conversion module, and a data acquisition module; The signal processing module is used to filter and amplify the output signal of the sensor. The A / D conversion module is used to convert the output signal after filtering and amplification into a digital signal. The data acquisition module is used to acquire the digital signal and transmit the digital signal to the current calculation module.

[0007] Furthermore, it also includes a temperature compensation module for adding corresponding compensation resistors to compensate for temperature-induced errors based on the real-time temperature measured by the temperature-sensitive element.

[0008] Secondly, the present invention provides a calibration method for the fieldbus pressure transmitter calibration system described in any of the above claims, executed by the control host, comprising: Obtain the resistance value of the pressure transmitter after the internal sensor deforms under external pressure; The current is obtained based on the resistance value; The error is obtained by subtracting the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit. When the error exceeds the maximum permissible error range of the pressure transmitter, a resistance set is used to replace the internal sensor to generate the deformed resistance value, providing the pressure transmitter with a zero-point reference, intermediate value reference, and full-scale reference to calibrate the pressure transmitter identification program.

[0009] Furthermore, with a set calibration time as the unit cycle, the resistance value after deformation is generated at least once in each unit cycle by replacing the internal sensor with a resistance set, so as to provide the zero-point reference, intermediate value reference and full-scale reference for the pressure transmitter to realize the calibration of the pressure transmitter identification program.

[0010] Furthermore, it also includes: when the value of at least one of the local external pressure and the remote external pressure is greater than the maximum measurement range of the pressure transmitter or less than the minimum measurement range of the pressure transmitter, calibrating the zero value and full scale value of the pressure transmitter by means of a 2-point calibration method.

[0011] Furthermore, it also includes: stopping self-calibration when the error between the local external pressure and the remote external pressure does not exceed the maximum permissible error range of the pressure transmitter.

[0012] Furthermore, it also includes: after calibration, comparing the local external pressure and the remote external pressure again. If the error between the local external pressure and the remote external pressure exceeds the maximum allowable error range again, multiple calibrations can be performed until the error is within the allowable error range after calibration.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: By adding a standard resistance set to a conventional pressure transmitter and introducing digital twin self-calibration technology, the standard resistance value calculated from the displayed value of the fieldbus pressure transmitter is equal to the resistance value obtained by the deformation of the sensor's sensitive element during pressure measurement. This resistance set replaces the resistance value generated by the internal sensor after deformation, providing zero-point, intermediate-value, and full-scale references for the pressure transmitter to calibrate its identification program. This eliminates the need to disassemble the pressure transmitter, enabling online inspection and calibration and improving measurement accuracy. Attached Figure Description

[0014] Figure 1 This is a flowchart of a fieldbus pressure transmitter calibration system provided in Embodiment 1 of the present invention.

[0015] Figure 2 is a flowchart of a fieldbus pressure transmitter calibration method provided in Embodiment 2 of the present invention.

[0016] Figure 3 is a schematic diagram of the interpolation principle in a fieldbus pressure transmitter calibration method provided in Embodiment 2 of the present invention. Detailed Implementation

[0017] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0018] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0019] To facilitate understanding, the components and proper nouns mentioned below will be explained: Pressure transmitter: The core component is the pressure sensor. Its working principle is based on the strain effect in physics. When external pressure is applied to the sensor, the sensor's sensitive element will deform, thereby changing its resistance value. This change in resistance value is proportional to the external pressure. By measuring the change in resistance value, the magnitude of the external pressure can be indirectly measured. Digital twin self-calibration technology: The standard resistance value calculated from the displayed value of the fieldbus pressure transmitter is equal to the resistance value obtained by the deformation of the sensor's sensitive element during pressure measurement. This is the theoretical core of self-calibration technology. Digital twin is a universally applicable theoretical and technical system that can be applied in many fields, including product design, product manufacturing, medical analysis, and engineering construction. Interpolation principle: as shown in the appendix Figure 3 As shown, this involves selecting points on a nonlinear curve and connecting adjacent points with line segments. This transforms the curve into a piecewise linear curve composed of many line segments. The more points selected, the closer the piecewise linear curve becomes to the original curve. By selecting effective points, the original nonlinear curve can be converted into a piecewise linear curve. The system bus serves as a bridge for communication between the bus pressure transmitter and external devices. Through the system bus, the transmitter can exchange data and send control commands with other devices. The communication protocol is crucial to ensuring the correct operation of the bus interface. It specifies the data transmission format, rate, and verification method. Common bus interfaces include I2C, SPI, and UART, while the communication protocol is customized according to the specific device and application requirements. Example 1:

[0020] Figure 1 This is a structural block diagram of the fieldbus pressure transmitter calibration system in Embodiment 1 of the present invention. The present invention provides a fieldbus pressure transmitter calibration system, including a control host and a resistance acquisition module, a current calculation module, an error acquisition module and a resistance substitution module connected to the control host. The error acquisition module includes a first pressure conversion unit and a second pressure conversion unit. The resistance acquisition module is used to acquire the resistance value of the pressure transmitter after the internal sensor deforms under external pressure. The current calculation module is used to obtain the current based on the resistance value. The current calculation module is a mature existing technology, which is a module that converts the resistance value into the current. The error acquisition module is used to obtain the error by subtracting the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit. The first pressure conversion unit and the second pressure conversion unit are both existing mature technologies. In this embodiment, their function is to convert the current value into the corresponding external pressure and display it at two different locations, remote and local. The resistor substitution module is used to replace the deformation resistance value generated by the internal sensor with a resistor set when the error exceeds the maximum permissible error range of the pressure transmitter, so as to provide the pressure transmitter with a zero-point reference, an intermediate value reference and a full-scale reference to achieve calibration of the pressure transmitter identification program.

[0021] It also includes a signal processing module, an A / D conversion module, and a data acquisition module, among which: The signal processing module is used to filter and amplify the output signal of the sensor. The A / D conversion module is used to convert the output signal after filtering and amplification into a digital signal. The data acquisition module is used to acquire the digital signal and transmit the digital signal to the current calculation module.

[0022] It also includes a temperature compensation module for adding corresponding compensation resistors to compensate for temperature-induced errors based on the real-time temperature measured by the temperature-sensitive element. To reduce temperature-induced errors, this embodiment proposes a method of adding a hardware temperature compensation resistor to the pressure transmitter. The principle is to add a temperature-sensitive element (such as a thermocouple or thermistor) inside the transmitter to measure the ambient temperature, and then add a corresponding compensation resistor based on the measured real-time temperature to compensate for the temperature-induced error, ultimately eliminating the error. Temperature compensation technology can greatly improve the accuracy and stability of pressure transmitters. When using pressure transmitters, a transmitter with an appropriate temperature compensation range and accuracy should be selected according to actual needs to ensure the system's performance and stability. Example 2:

[0023] Figure 2 This is a flowchart of the fieldbus pressure transmitter calibration method according to Embodiment 2 of the present invention. This flowchart only illustrates the logical sequence of the method described in this embodiment. Provided there are no conflicts, different methods may be used in other possible embodiments of the present invention. Figure 1 Complete the steps shown or described in the order indicated.

[0024] The fieldbus pressure transmitter calibration method provided in this embodiment can be applied to a terminal and can be executed by a fieldbus pressure transmitter calibration device. This device can be implemented in software and / or hardware and can be integrated into the terminal, such as any smartphone, tablet, or computer device with communication capabilities. See also... Figure 1 This embodiment is based on digital twin self-calibration technology. The method disclosed in this embodiment can be executed by the control host of the fieldbus pressure transmitter calibration system disclosed in Embodiment 1, and specifically includes the following steps: Step 1: Obtain the resistance value of the internal sensor of the pressure transmitter after deformation under external pressure; Regarding the resistance set determined by the resistance change range of the sensitive element, it can be understood that the resistance value of the resistance set is determined by the resistance change range when the sensor probe is deformed. Step 2: Obtain the current based on the resistance value; Step 3: The difference between the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit is processed to obtain the error. Step 4: When the error exceeds the maximum permissible error range of the pressure transmitter, the maximum permissible error range can be selected to be greater than 1 / 2 of the maximum permissible error. The resistance value after deformation is generated by replacing the internal sensor with a resistance set, so as to provide the zero point reference, intermediate value reference and full scale reference for the pressure transmitter to realize the calibration of the pressure transmitter identification program. The resistance value of the resistor set is controlled by the control host. In this embodiment, the maximum resistance range of the transmitter, 10Ω, is defined as the upper limit of measurement. At this time, 10Ω is converted into 20mA current in the current calculation module. The 20mA current is then output as a pressure value through the first pressure conversion unit and the second pressure conversion unit, providing a full-scale reference for the pressure transmitter. In this embodiment, the minimum resistance range of the transmitter, 0Ω, is defined as the lower limit of measurement. At this time, 0Ω is converted into 4mA current in the internal current calculation module. The 4mA current is then output as a pressure value through the first pressure conversion unit and the second pressure conversion unit, providing a zero-scale reference for the pressure transmitter. The resistance value range of the transmitter (0-10Ω) is defined as the intermediate resistance value. The intermediate resistance value is input into the current calculation module and converted into a corresponding current. The corresponding current is output as a pressure value through the first pressure conversion unit and the second pressure conversion unit, providing an intermediate value reference for the pressure transmitter. The resistance value variation range of the resistor set in this embodiment is 0-10Ω, and the corresponding resistance-current relationship is shown in Table 1. 4mA 5.6 mA 7.2 mA 8.8 mA 10.4 mA 12mA 13.6 mA 15.2 mA 16.8 mA 18.4 mA 20mA Table 1 Pressure transmitter malfunctions or errors exceeding the range are usually caused by the recognition program within the pressure transmitter losing its conversion correspondence, resulting in an imbalance in circuit characteristics. In this embodiment, a resistor set is used to replace the internal sensor to generate the deformed resistance value, thereby correcting the correspondence between resistance and current.

[0025] Typically, the experimental calibration of pressure transmitters only requires two points: calibration of the zero-point pressure and full-scale pressure. After calibration, the identification program will automatically perform proportional calculations based on a linear law. When the pressure value of at least one of the local external pressure and the remote external pressure is greater than the maximum measurement range of the pressure transmitter or less than the minimum measurement range of the pressure transmitter, the zero value and full scale value of the pressure transmitter are calibrated by the 2-point calibration method.

[0026] The identification program is a mature technology of existing pressure transmitters. It has a calibration function that can correct the correspondence between resistance and current. This can be achieved by inputting resistance values ​​of different ranges, such as zero range, intermediate range and full scale.

[0027] If the linear relationship between resistance and current is not applicable throughout the pressure range, multi-point linear correction is performed. The program logic for multi-point linear correction uses the interpolation principle, which has been explained above. Self-calibration stops when the error between the local external pressure and the remote external pressure does not exceed the maximum permissible error range of the pressure transmitter.

[0028] In addition, after calibration, the local external pressure and the remote external pressure are compared again. If the error between the local external pressure and the remote external pressure exceeds the maximum allowable error range again, multiple calibrations can be performed until the error is within the allowable error range after calibration.

[0029] Step 5: Using the set calibration time as the unit cycle, at least once in each unit cycle, the resistance value after deformation is generated by replacing the internal sensor with a resistance set, so as to provide the zero-point reference, intermediate value reference and full-scale reference for the pressure transmitter to realize the calibration of the pressure transmitter identification program.

[0030] In addition, it includes: after calibration, comparing the local external pressure and the remote external pressure again. When the error between the local external pressure and the remote external pressure exceeds the maximum allowable error range again, multiple calibrations can be performed until the error is within the allowable error range after calibration.

[0031] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0032] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0033] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0034] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0035] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fieldbus pressure transmitter calibration system, characterized in that, It includes a control host and a resistance acquisition module, a current calculation module, an error acquisition module and a resistance substitution module that are signal-connected to the control host. The error acquisition module includes a first pressure conversion unit and a second pressure conversion unit. The resistance acquisition module is used to acquire the resistance value of the pressure transmitter after the internal sensor deforms under external pressure. The current calculation module is used to obtain the current based on the resistance value; The error acquisition module is used to obtain the error by subtracting the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit. The resistor substitution module is used to replace the deformation resistance value generated by the internal sensor with a resistor set when the error exceeds the maximum permissible error range of the pressure transmitter, so as to provide the pressure transmitter with a zero-point reference, an intermediate value reference and a full-scale reference to achieve calibration of the pressure transmitter identification program.

2. The fieldbus pressure transmitter calibration system according to claim 1, characterized in that, It also includes a signal processing module, an A / D conversion module, and a data acquisition module; The signal processing module is used to filter and amplify the output signal of the sensor. The A / D conversion module is used to convert the output signal after filtering and amplification into a digital signal. The data acquisition module is used to acquire the digital signal and transmit the digital signal to the current calculation module.

3. The fieldbus pressure transmitter calibration system according to claim 1, characterized in that, It also includes a temperature compensation module for adding corresponding compensation resistors to compensate for temperature-induced errors based on the real-time temperature measured by the temperature-sensitive element.

4. A fieldbus pressure transmitter calibration method, applied to the fieldbus pressure transmitter calibration system according to any one of claims 1-3, executed by the control host, characterized in that, include: Obtain the resistance value of the pressure transmitter after the internal sensor deforms under external pressure; The current is obtained based on the resistance value; The error is obtained by subtracting the local external pressure displayed by the first pressure conversion unit and the remote external pressure displayed by the system bus and the second pressure conversion unit. When the error exceeds the maximum permissible error range of the pressure transmitter, a resistance set is used to replace the internal sensor to generate the deformed resistance value, providing the pressure transmitter with a zero-point reference, intermediate value reference, and full-scale reference to calibrate the pressure transmitter identification program.

5. The fieldbus pressure transmitter calibration method according to claim 4, characterized in that, Using a set calibration time as the unit cycle, at least once per unit cycle, the resistance value after deformation is generated by replacing the internal sensor with a resistance set, providing the pressure transmitter with a zero-point reference, intermediate value reference, and full-scale reference to calibrate the pressure transmitter identification program.

6. The fieldbus pressure transmitter calibration method according to claim 4 or 5, characterized in that, Also includes: When the value of at least one of the local external pressure and the remote external pressure is greater than the maximum measurement range of the pressure transmitter or less than the minimum measurement range of the pressure transmitter, the zero value and full scale value of the pressure transmitter are calibrated by the 2-point calibration method.

7. The fieldbus pressure transmitter calibration method according to claim 4, characterized in that, Also includes: Self-calibration stops when the error between the local external pressure and the remote external pressure does not exceed the maximum permissible error range of the pressure transmitter.

8. The fieldbus pressure transmitter calibration method according to claim 4 or 5, characterized in that, Also includes: After calibration, the local external pressure and the remote external pressure are compared again. If the error between the local external pressure and the remote external pressure exceeds the maximum allowable error range again, multiple calibrations can be performed until the error is within the allowable error range after calibration.

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