Thermistor signal simulation device and method for nuclear power plant core instrumentation systems

Abstract

The application discloses a kind of thermistor signal simulation device and method for nuclear power plant reactor core measuring system, device includes controller, programmable logic device, digital-analog conversion unit, operational amplifier and analog switch;Theoretical voltage value of output is obtained by controller through the current value and thermistor value of four-wire thermocouple measurement channel collected;Programmable logic device generates voltage signal according to theoretical voltage value output signal Digital-analog conversion unit, and generates n-way output voltage by downstream n-way operational amplifier, to simulate four-wire thermistor signal;N-way output voltage signal end is connected with a way analog switch respectively;N-way analog switch is all opened and closed by programmable logic device, and is tested as thermistor simulation signal.The application utilizes digital processing and control technology, can output high-precision resistance signal and simultaneously provide multiple analog signals, so that the thermistor measurement function test of reactor core measuring system is more convenient and accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear power plant core measurement, in particular to a thermistor signal simulation device and method for a nuclear power plant core measurement system. BACKGROUND

[0002] In order to monitor the nuclear power plant, the core cooling monitoring system using the core measurement system collects and processes signals from the core temperature and core water level probe, provides a direct current power supply for the water level probe, and sends the processed information to the control room display through hardwiring or network.

[0003] In order to confirm the function and performance of the core cooling monitoring system equipment and ensure that it can realize the core cooling monitoring function, the core cooling monitoring system needs to be tested. Among them, the Pt100 thermistor simulation signal is provided for the core cooling monitoring system equipment, and the thermistor simulation signal is required to have the characteristics of high precision and high reliability.

[0004] The wiring method of the four-wire thermistor is to connect two wires at both ends of the root of the thermistor, of which two wires provide a constant current for the thermistor to convert the resistance signal into a voltage signal, and the voltage value is measured through the other two wires. This lead method can completely eliminate the resistance influence of the lead.

[0005] Currently, when providing a thermistor simulation signal, a resistance or an instrument is generally used to temporarily build a test environment for testing. When using a resistance or an instrument to simulate a thermistor signal, the temperature value required for testing needs to be converted into a resistance value by looking up a table first, and then the resistance or the output resistance value of the instrument needs to be changed. However, the core cooling monitoring system has 24 thermistor channels, and it needs to modify the wiring and set the resistance value many times to complete a test, which brings inconvenience to the test and it is difficult to ensure the precision and reliability. Therefore, a thermistor signal simulation device and method are needed to solve the problem of complicated test steps and low precision of the existing thermistor simulation technology. SUMMARY

[0006] In order to solve the problem of complicated test steps and low precision caused by the existing thermistor simulation technology, the present application provides a thermistor signal simulation device and method for a nuclear power plant core measurement system. The present application uses digital processing and control technology to output high-precision resistance signals and provide multiple analog signals at the same time, making the thermistor measurement function test of the core measurement system more convenient and accurate.

[0007] The present application is implemented by the following technical solutions:

[0008] The thermistor signal simulation device for a nuclear power plant core measurement system comprises a controller, a programmable logic device, a digital-to-analog conversion unit, an operational amplifier, and an analog switch.

[0009] The controller automatically obtains corresponding thermal resistance values according to the temperature value to be measured, and calculates the output theoretical voltage value through the current value and the thermal resistance value of the four-wire thermal couple measurement channel collected.

[0010] The programmable logic device controls the digital-to-analog conversion unit to generate a voltage signal according to the theoretical voltage value output signal, and generates n output voltages through the n operational amplifiers downstream to simulate the four-wire thermal resistance signal.

[0011] The n output voltage signal ends are respectively connected to one analog switch; the n analog switches are all controlled to open and close by the programmable logic device, so as to control the output voltage signal to be input to the reactor core measurement system as a thermal resistance simulation signal for testing.

[0012] As a preferred embodiment, the device of the application further comprises a current measurement unit and an analog-to-digital conversion unit.

[0013] The current measurement unit is used to collect the current value of the four-wire thermal couple measurement channel, and the collected current value is sent to the controller after being converted by the analog-to-digital conversion unit.

[0014] As a preferred embodiment, the device of the application further comprises a human-computer interaction interface.

[0015] The human-computer interaction interface and the thermal resistance signal simulation device are designed integrally.

[0016] Alternatively, the human-computer interaction interface can be designed independently of the thermal resistance signal simulation device.

[0017] As a preferred embodiment, the human-computer interaction interface of the application provides human-computer interaction for setting the temperature value to be measured.

[0018] The human-computer interaction interface can also be used for data display and fault alarm.

[0019] As a preferred embodiment, when the human-computer interaction interface of the application is designed independently of the thermal resistance signal simulation device, the human-computer interaction interface can adopt an industrial computer.

[0020] The industrial computer and the controller are connected in communication through RS232, and the industrial computer and the reactor core measurement system are connected in communication through RS485.

[0021] As a preferred embodiment, the industrial computer of the application can obtain the actual measurement value of the four-wire thermal resistance of the reactor core measurement system, and perform error calculation with the set temperature value to be measured, and display the theoretical value, the measurement value and the error.

[0022] As a preferred embodiment, the human-computer interaction interface of the application can display and alarm the interface disconnection or the output error of the constant current source exceeding the range.

[0023] As a preferred embodiment, the programmable logic device of the present application adopts FPGA.

[0024] As a preferred embodiment, the present application takes n as less than or equal to 24.

[0025] In another aspect, the present application provides a thermistor signal simulation method for a nuclear power plant core measurement system, which comprises:

[0026] According to the temperature value to be measured, the corresponding thermistor value is obtained by automatic table lookup, and the output theoretical voltage value is calculated through the current value and the thermistor value collected from the four-wire thermocouple measurement channel;

[0027] The digital-to-analog conversion unit is controlled by the programmable logic device to generate a voltage signal, and the n-way operational amplifier downstream follows to generate n-way output voltage to simulate the four-wire thermistor signal;

[0028] The n-way output voltage signal end is respectively connected with one analog switch, and the n-way analog switch is controlled by the programmable logic device to realize input of the corresponding output voltage signal to the core measurement system as a thermistor simulation signal for testing.

[0029] The present application has the following advantages and beneficial effects:

[0030] The thermistor signal simulation device provided by the present application sends the measured current value and the alarm signal to the man-machine interface display by collecting the current value of the four-wire thermistor measurement channel to be measured to monitor whether the current value error exceeds the range or a wire break occurs. The temperature or thermistor value to be simulated can be set on the man-machine interface, when the set value is the temperature value, the controller automatically looks up the corresponding thermistor value, and according to the set temperature value, the corresponding resistance value is obtained by table lookup, and the output voltage value is calculated through the current value and the theoretical resistance value. The controller output signal is converted into a voltage value by DAC and output to the four-wire thermistor acquisition channel to simulate the thermistor signal.

[0031] The present application can realize 24-way parallel thermistor simulation signal output, and the output voltage after operational amplification is 20mV-38mV, and the output voltage precision is better than 0.1%.

[0032] The present application is particularly suitable for core cooling monitoring systems, provides thermistor simulation signals for core cooling monitoring systems, and has been supplied to Fujian Fuqing Nuclear Power Plant Units 5 and 6, Karachi Nuclear Power Plant Units 2 and 3 in Pakistan, and Fujian Zhangzhou Nuclear Power Plant Units 1 and 2, and will be supplied to Hainan Changjiang Nuclear Power Plant Units 3 and 4. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0034] Figure 1 It is a schematic diagram of the device of the embodiment of the application. DETAILED DESCRIPTION

[0035] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments and drawings, and the illustrative embodiments of the present application and the description thereof are only used to explain the present application and do not constitute limitations on the present application.

[0036] Embodiment 1

[0037] The existing method for providing a Pt100 thermal resistance analog signal for a reactor core cooling monitoring system needs to modify the wiring multiple times to complete a test, which is inconvenient for testing and is difficult to guarantee the accuracy and reliability. Based on this, the embodiment provides a thermal resistance signal simulation device for a reactor core measurement system of a nuclear power plant.

[0038] Specifically Figure 1 As shown in the figure, the thermal resistance signal simulation device of the embodiment of the application comprises a controller, a programmable logic device, a digital-to-analog conversion unit, an operational amplifier, an analog switch, a current measurement unit and an analog-to-digital conversion unit.

[0039] The output end of the controller is in communication connection with the input end of the programmable logic device, the output end of the programmable logic device is connected with the input end of the digital-to-analog conversion unit, the output end of the digital-to-analog conversion unit is in communication connection with the input end of the n-way operational amplifier, and the output end of the n-way operational amplifier is connected with the reactor core cooling monitoring system through an analog switch, so as to simulate the voltage value generated by the n-way four-wire thermal resistance. In the embodiment of the application, 24-way four-wire thermal resistance channels of the reactor core cooling monitoring system can be tested at the same time, that is, n=24; or according to actual needs, multiple analog signals can be output to realize the test of multiple four-wire thermal resistance channels, that is, n is less than 24.

[0040] The input end of the controller is connected with the output end of the analog-to-digital conversion unit, the input end of the analog-to-digital conversion unit is connected with the output end of the current measurement unit, and the input end of the current measurement unit is connected with the measurement channel of the four-wire thermal resistance, so as to collect the resistance value of the measurement channel of the four-wire thermal resistance to be measured.

[0041] The temperature range and corresponding theoretical thermal resistance value mapping table are built in the controller, and the controller automatically obtains the corresponding theoretical thermal resistance value according to the temperature to be measured by looking up the table.

[0042] The controller calculates the theoretical voltage value based on the theoretical thermal resistance value obtained by looking up and the current value of the four-wire thermal resistance measurement channel collected, and outputs the theoretical voltage value to the programmable logic device.

[0043] The programmable logic device can be, but is not limited to, FPGA, and the programmable logic device controls the digital-to-analog conversion unit to generate a 0-2.5V voltage signal according to the theoretical voltage value output signal, with a precision better than 0.1%, and 3 DACs are used to output 24 voltage signals at the same time, and a follower operational amplifier is used to make the output voltage range 20mV-38mV, which is output to the four-wire thermal resistance measurement channel to simulate the four-wire thermal resistance signal. Each output voltage signal is connected to a high-precision single analog switch, which is controlled by the programmable logic device to open and close, and the output voltage signal is stopped when the test is manually stopped or the line is disconnected.

[0044] The current measurement unit collects the current value of the four-wire thermal resistance measurement channel to be measured, and converts the current value through an analog-to-digital conversion device and feeds back to the controller for calculating the theoretical voltage value. In the embodiment of the present application, the current measurement unit can be connected to the controller through RS485 communication.

[0045] The working principle of the thermal resistance signal simulation device proposed in the embodiment of the present application is as follows:

[0046] The current value of the four-wire thermal resistance measurement channel to be measured is collected, and the temperature or thermal resistance value to be simulated is set. When the set value is a temperature value, the controller automatically looks up the table to obtain the corresponding thermal resistance value, and the output voltage value is calculated by the current value and the theoretical resistance value. The controller controls the programmable logic device to output a signal converted into a voltage value by DAC, and a follower operational amplifier is used to generate high output impedance to the four-wire thermal resistance test channel to simulate the thermal resistance signal. At the same time, the current value of the four-wire thermal resistance test channel is collected by the current collection unit, and the test results are calculated and monitored for errors.

[0047] The simulation device of the embodiment of the present application adopts digital technology, calculates the theoretical voltage value, and then controls the DAC by using a programmable device such as FPGA to make it output the required voltage value, and combines the follower operational amplifier to generate multiple parallel thermal resistance simulation signals, which is convenient for testing, has high precision, and is controllable.

[0048] The simulation device can realize 24-way parallel thermistor simulation signal output, and the output voltage is 20mV-38mV after being output by an operational amplifier, and the output voltage precision is better than 0.1%.

[0049] The working process of the thermistor signal simulation device is as follows:

[0050] According to the to-be-measured temperature value, the corresponding thermistor value is obtained by automatically looking up a table, and the theoretical voltage value of the output is calculated through the current value and the thermistor value of the four-wire thermocouple measurement channel collected;

[0051] The digital-to-analog conversion unit is controlled by the programmable logic device to generate a voltage signal, and the n-way operational amplifier downstream follows to generate n-way output voltage to simulate the four-wire thermistor signal;

[0052] The n-way output voltage signal end is connected with the n-way analog switch, and the n-way analog switch is controlled by the programmable logic device to realize input of the corresponding output voltage signal to the reactor core measurement system as a thermistor simulation signal for testing.

[0053] The signal simulation device further comprises a man-machine interface, which can be a device designed integrally with the signal simulation device, or a device independent of the signal simulation device, such as an industrial computer device.

[0054] The temperature value or the thermistor value to be simulated can be set through the man-machine interface, when the set value is the temperature value, the controller automatically looks up the corresponding theoretical thermistor value according to the set temperature value, and calculates the theoretical voltage value of the output according to the collected current value and the theoretical thermistor value.

[0055] The current measurement unit collects the current value output by the reactor core cooling monitoring system, converts the current value into a digital signal through the analog-to-digital conversion unit, and sends the digital signal to the controller for display on the man-machine interface, thereby realizing the current value monitoring function.

[0056] Embodiment 2

[0057] This embodiment illustrates the thermistor signal simulation device proposed in the above embodiment by taking an example.

[0058] The core cooling monitoring system of the core measurement system has 24 four-wire resistance measurement channels, and the rated current value is 200 mu A.

[0059] The thermal resistance simulation device reads the current value output by the core cooling monitoring system, converts it into a digital signal through AD conversion, and sends it to the controller, which displays it on the human-computer interaction interface to realize current value monitoring function. If the interface is disconnected or the constant current source output error exceeds the range, an alarm will be sent on the human-computer interaction interface.

[0060] Through the human-computer interaction interface, set the measured temperature to 200 DEG C, the controller automatically looks up the table to get the theoretical thermal resistance value, and then calculates the corresponding voltage value of 38 mV with the monitored current value of 200 mu A. The FPGA outputs a signal to the DAC to generate a 0-2.5V signal, which is output to the core cooling monitoring system of the core measurement system through the following operational amplifier, with an accuracy of better than 0.1%.

[0061] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application, and the technical solutions disclosed by the present application can be realized by other ways. For example, the division of the modules is only a logical function division, and actual implementation can have another division way, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the communication connection between the modules can be indirect coupling or communication connection through some interfaces, devices or units, which can be electrical signals or other forms.

[0062] In addition, each functional module in each embodiment of the present application can be integrated in one processing unit, or each module can exist physically, or two or more modules can be integrated in one processing unit. The integrated unit can be realized in the form of hardware or software functional unit.

[0063] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in the part that contributes to the prior art, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions that cause a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

Claims

1. A thermistor signal simulation device for a nuclear power plant core measurement system, characterized by, The controller, the programmable logic device, the digital-to-analog conversion unit, the operational amplifier and the analog switch are included. The controller automatically obtains the corresponding thermal resistance value according to the measured temperature value, and calculates the output theoretical voltage value through the collected current value and thermal resistance value of the four-wire thermal couple measurement channel. The programmable logic device controls the digital-to-analog conversion unit to generate a voltage signal according to the theoretical voltage value output signal, and generates n-way output voltage through the downstream n-way operational amplifier to simulate the four-wire thermal resistance signal. The n-way output voltage signal terminals are respectively connected to one-way analog switch, and the n-way analog switch is controlled by the programmable logic device to control the input of the output voltage signal to the core measurement system as the thermal resistance simulation signal for testing.

2. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 1, characterized in that, The current measurement unit and the analog-to-digital conversion unit are further included. The current measurement unit is used to collect the current value of the four-wire thermal couple measurement channel, and the collected current value is converted by the analog-to-digital conversion unit and sent to the controller.

3. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 1, characterized in that, The human-computer interaction interface is further included. The human-computer interaction interface and the thermal resistance signal simulation device are designed integrally. Alternatively, the human-computer interaction interface can be designed independently of the thermal resistance signal simulation device.

4. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 3, characterized in that, The human-computer interaction interface provides human-computer interaction for setting the measured temperature value. The human-computer interaction interface can also be used for data display and fault alarm.

5. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 3, characterized in that, When the human-computer interaction interface is designed independently of the thermal resistance signal simulation device, the human-computer interaction interface can adopt an industrial computer. The industrial computer and the controller are connected by RS232 communication, and the industrial computer and the core measurement system are connected by RS485 communication.

6. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 5, characterized in that, The industrial computer can obtain the actual measurement value of the four-wire thermal resistance of the core measurement system, calculate the error with the set measured temperature value, and display the theoretical value, the measurement value and the error.

7. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to claim 3, characterized in that, The human-computer interaction interface can display and alarm the interface disconnection or the output error of the constant current source exceeding the range.

8. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to any one of claims 1 to 7, characterized in that The programmable logic device adopts FPGA.

9. A thermistor signal simulation device for a nuclear power plant core instrumentation system according to any one of claims 1 to 7, characterized in that, The value of n is less than or equal to 24.

10. A method for thermistor signal simulation for a nuclear power plant core measurement system, characterized by, The method comprises: According to the measured temperature value, the corresponding thermal resistance value is automatically obtained by looking up the table, and the output theoretical voltage value is calculated through the collected current value and thermal resistance value of the four-wire thermal couple measurement channel. The programmable logic device controls the digital-to-analog conversion unit to generate a voltage signal, and the downstream n-way operational amplifier follows to generate n-way output voltage to simulate the four-wire thermal resistance signal. The n-way output voltage signal terminals are respectively connected to one-way analog switch, and the n-way analog switch is controlled by the programmable logic device to control the input of the output voltage signal to the core measurement system as the thermal resistance simulation signal for testing.

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