CN112863713A - Primary loop gas humidity measuring circuit for high-temperature gas cooled reactor - Google Patents
Primary loop gas humidity measuring circuit for high-temperature gas cooled reactor Download PDFInfo
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Abstract
The invention discloses a primary loop gas humidity measuring circuit for a high-temperature gas cooled reactor, which comprises a sensor unit, a primary sampling circuit and a secondary signal conversion circuit which are sequentially connected; the sensor unit is arranged in a helium sampling chamber of a primary loop of the high-temperature gas cooled reactor, the primary sampling circuit carries out sensor excitation and signal acquisition on the sensor unit, an equal dew point curve of an output voltage signal of the sensor unit is obtained under a standard humidity test environment, and a low-humidity and high-humidity range humidity calculation transfer function is calculated through the equal dew point curve; the secondary signal conversion circuit utilizes a humidity calculation transfer mathematical model, and realizes temperature correction of a humidity measured value through linear conversion and the correlation between humidity and temperature; and is connected to a remote reactor protection system via a second shielded cable. The invention adopts a pure hardware mode, does not comprise a programmable device and a digital processor in the circuit, does not need software programming and V & V verification, and has better implementation effect.
Description
Technical Field
The invention relates to the technical field of primary loop gas humidity measurement for a high-temperature gas cooled reactor, in particular to a primary loop gas humidity measurement circuit for the high-temperature gas cooled reactor.
Background
The high-temperature gas cooled reactor belongs to a fourth generation advanced reactor with inherent safety, and China is in the leading position in the field of research and engineering construction of the reactor type. Helium is adopted by the high-temperature gas cooled reactor as a primary loop coolant, the humidity of the helium needs to be measured in real time when the reactor is in service, and a humidity measurement signal is converted into a 4-20 mA current signal meeting an industrial instrument interface and is transmitted to a reactor protection system.
When the high-temperature gas cooled reactor normally operates, the moisture content in the helium gas of the primary loop is very low and is lower than minus 40 ℃ dp, and when liquid water or water vapor enters the primary loop system due to a pipeline break accident or other serious accidents, the humidity of the helium gas of the primary loop is rapidly increased to a humidity alarm value or a protection fixed value, and a humidity overrun alarm or reactor protection shutdown is triggered. The measuring range of the helium humidity measuring circuit covers a low humidity measuring range and a high humidity measuring range. Meteorological and other industrial environment humidity measuring circuit or humidity measuring device are only used for certain single humidity range humidity to measure, and humidity meter on the current market adopts singlechip or microcontroller as humidity sampling data processing unit, adopts software programming mode to calculate the humidity value and prestore the parameter through the memory and revise the humidity measurement result. The humidity instrument applied to the loop humidity measurement of the high-temperature gas cooled reactor belongs to a safety-level instrument, all the humidity instruments in the market do not perform V & V certification of software, industrial-level humidity measurement equipment manufacturers consider commercial confidentiality and research and development cost, embedded software, a temperature correction algorithm and codes of the humidity measurement instrument are non-open sources for users or nuclear power plant owners, and users cannot perform instrument software certification and safety-level certification.
Disclosure of Invention
The invention aims to solve the technical problems that the humidity value of primary loop gas for the conventional high-temperature gas-cooled reactor nuclear power station is calculated by adopting a software programming mode and the humidity measurement result is corrected by pre-storing parameters in a memory, so that the third-party verification time and identification cost of software are wasted, and the defect that the requirement of a safety-level instrument for a nuclear power plant is not met exists. The invention aims to provide a primary loop gas humidity measuring circuit for a high-temperature gas-cooled reactor, which is suitable for measuring the gas humidity of a primary loop for a high-temperature gas-cooled reactor nuclear power station, covers a low-humidity measuring range and a high-humidity measuring range, and realizes the sampling and conversion of temperature and humidity sensor signals by adopting a full hardware mode; and provides a temperature deviation correction method aiming at the temperature deviation existing in the humidity sensor during the use process.
The invention is realized by the following technical scheme:
a primary loop gas humidity measuring circuit for a high temperature gas cooled reactor comprises: the signal output of the primary sampling circuit is connected with the sensor unit, the signal output of the primary sampling circuit is connected with the signal output of the secondary signal conversion circuit through a signal cable with a shielding layer, and the signal cable meets the use requirement of a safety level instrument;
the sensor unit is arranged in a helium sampling chamber of a primary loop of the high-temperature gas cooled reactor and is in direct contact with helium, the sensor unit is connected to the input end of a primary sampling circuit, an output voltage signal of the primary sampling circuit is connected with a secondary signal conversion circuit through a first shielded cable, the primary sampling circuit carries out sensor excitation and signal acquisition on the sensor unit, an equal dew point curve of the output voltage signal of the sensor unit (namely a humidity sensor and a temperature sensor) is obtained in a standard humidity testing environment, and a low-humidity and high-humidity range humidity calculation transfer function is calculated through the equal dew point curve; the secondary signal conversion circuit utilizes the humidity calculation transfer mathematical model to realize temperature correction of a humidity measured value through linear conversion and the correlation between the humidity and the temperature; and outputting a current signal after correction, and connecting the current signal with a remote reactor protection system through a second shielded cable.
The working principle is as follows: the method is based on the defect that the requirement of a safety-level instrument for a nuclear power plant is not met. The invention designs a primary loop gas humidity measuring circuit for a high-temperature gas cooled reactor, wherein a primary sampling circuit and a secondary signal conversion circuit both adopt a hardware circuit mode, a digital chip and software programming are not adopted, and the problems of software code open source and V & V certification are solved. Specifically, the present invention comprises: the sensor unit is arranged in a loop helium gas humidity measurement sampling chamber and comprises a humidity sensor and a temperature sensor; the primary sampling circuit is used for exciting the sensor unit and acquiring signals, the primary sampling circuit is used for obtaining equal dew point curves of output voltage signals of the humidity sensor and the temperature sensor in a standard humidity testing environment, and the equal dew point curves are used for calculating humidity calculation transfer functions in low humidity and high humidity ranges; the secondary signal conversion circuit finishes signal linear conversion and temperature correction of a humidity calculation mathematical model, the secondary signal conversion circuit is divided into a linear amplification module, a humidity measurement range selection module, a V/I conversion module and a power supply module, when the humidity calculation and temperature correction mathematical model is realized on a hardware circuit, the linear amplification module is divided into a low-humidity amplification channel and a high-humidity amplification channel, each amplification channel is composed of two stages of amplification circuits, and the two stages of amplification modes are adopted to facilitate circuit debugging and precision parameter adjustment.
The humidity measuring circuit and the temperature correcting method for the high-temperature gas cooled reactor are realized in a pure hardware mode, a programmable device and a digital processor are not included in the circuit, software programming and V & V verification are not needed, the identification period and the research and development cost of the safety-level humidity measuring instrument for the nuclear power plant are shortened, and the implementation effect is good.
Further, the sensor unit includes a humidity sensing element and a temperature sensing element;
the humidity sensing element is a humidity sensor and adopts a capacitance type humidity sensor or a resistance type humidity sensor; the temperature sensing element is a temperature sensor, and the type of the temperature sensor is Pt 100. The humidity sensor and the temperature sensor are simultaneously arranged in the filter cover with the protection function; as close as possible.
The capacitance type humidity sensor adopts oscillation excitation and carries out a signal acquisition mode through F/V conversion, or adopts a sensor excitation and signal acquisition integrated circuit chip.
Further, in order to reduce distributed capacitance and lead resistance, the humidity sensor and the temperature sensor are directly connected with the primary sampling circuit through leads which are as short as possible, and the leads are connected with a circuit board of the primary sampling circuit in a soldering mode.
Further, the primary sampling circuit excites the humidity sensor and the temperature sensor, converts the capacitance value or the resistance value of the humidity sensor into a voltage signal, and converts the resistance value of the temperature sensor into a voltage signal;
the excitation mode of the capacitance type humidity sensor comprises the following steps: adopting a mode of exciting an oscillating circuit and adding F/V or C/V conversion; adopting a capacitance value or resistance value measurement integrated chip to directly convert the capacitance value or the resistance value of the humidity sensor into a voltage signal;
the resistance type temperature sensor is excited by adopting a constant current source to output constant current to the sensor and collecting the voltage at two ends of the sensor.
The connection of the front-end sensor unit should be as close as possible to the primary sampling circuit board to reduce the distributed capacitance and lead resistance of the sensor leads.
Furthermore, the primary sampling circuit is matched with the secondary signal conversion circuit to cover the humidity measurement in a low humidity range and a high humidity range; wherein the low humidity range is-20 ℃ dp to +10 ℃ dp, and the high humidity range is 10 ℃ dp to +40 ℃ dp.
Further, under the standard humidity measurement environment, a humidity sensor signal and a temperature sensor signal output by the primary sampling circuit are tested, dew point lines such as a humidity sensor are obtained by utilizing test data, and a humidity calculation mathematical model is established.
Further, the secondary signal conversion circuit realizes the division of the humidity measurement range and the hardware circuit realization of the temperature compensation model. The secondary signal conversion circuit comprises a linear amplification module, a humidity measurement range selection module, a V/I conversion module and a power supply module which are connected in sequence;
the linear amplification module is used for realizing the linear transformation of the humidity sensor signal and the temperature compensation of different humidity measurement ranges; the linear amplification module comprises a low-humidity measurement linear amplification channel and a high-humidity measurement linear amplification channel;
the measurement range selection module is used for carrying out logic judgment according to the voltage value of the humidity sensor output by the primary sampling circuit and selecting the output value of the low-humidity measurement linear amplification channel or the high-humidity measurement linear amplification channel as the output value of proportional amplification and linear temperature compensation;
the V/I conversion module is used for converting the voltage value output by the proportional amplification and linear temperature compensation model into a current value in a range of 4-20 mA, and the current value is transmitted to a far-end reactor protection system through a safety-level second shielding cable, and the current-voltage conversion can be realized through a current loop or a conversion chip;
the power supply module converts an external input 24VDC voltage into a voltage value required by the operation of the primary sampling circuit and the secondary signal conversion circuit to supply power to the primary sampling circuit and the secondary signal conversion circuit.
Further, the linear temperature compensation model is used for measuring the humidity and the (K) of the helium gas in the primary loop in the low-humidity and high-humidity measurement rangesoT + Vm) is approximately linearly related, the resistance of the Pt100 temperature sensor is linearly related to the temperature, the temperature sensor output signal Vt is substituted for T, and the functional relation of the linear temperature compensation model (i.e., the low humidity and high humidity range humidity calculation transfer function is calculated by the equal Dew point curve) can be obtained as dw ═ a (k)m*Vt+Vm)+b；
Wherein Dew is the gas humidity Dew point value; ko、kmIs a temperature coefficient; t is a gas temperature value; vt is a temperature sensor signal; vm is the humidity sensor signal; a. b is a linear transfer function correction coefficient.
In the helium humidity measurement range, if the same temperature compensation coefficient and correction coefficient are adopted, the humidity measurement precision is lower. The helium humidity measurement range is divided into a low humidity range (-20 ℃ dp to +10 ℃ dp) and a high humidity range (10 ℃ dp to +40 ℃ dp) by analyzing isodew points at different temperatures, and different temperature coefficients and transfer function correction coefficients are adopted in the two humidity measurement ranges.
Furthermore, in order to facilitate the adjustment and debugging of circuit parameters of the linear amplification channel of the secondary signal conversion circuit, the linear amplification channel is a first-stage amplification channel and a second-stage amplification channel in a hardware structure; specifically, the linear temperature compensation model includes a first stage amplification and a second stage amplification, wherein:
the first stage amplification transfer function is:
Vo1＝mo1*Vm+n01vt; vm is the value of the humidity sensor of the primary sampling circuit; vt is the temperature sensor value of the primary sampling circuit; m iso1、n01Is a coefficient;
the transfer function of the second stage amplification is:
Vo2＝mo2*Vo1+n02；Vo1an output value for the first stage amplification;
in the low-humidity measurement range and the high-humidity measurement range, the proportionality coefficient mo1、n01、mo2、n02Are different values.
Further, according to the output signal value of the humidity sensor of the primary sampling circuit, the humidity measurement range selection module selects the output voltage value of the low-humidity amplification channel or the high-humidity amplification channel, when the voltage value of the humidity sensor is smaller than a certain voltage value Vd, the output of the low-humidity linear amplification channel is selected as the input voltage value of the V/I conversion module, when the voltage value of the humidity sensor is larger than Vd + H, wherein H is a return difference value, the output of the high-humidity linear amplification channel is selected as the input voltage value of the V/I conversion module, and when the voltage value of the humidity sensor is larger than or equal to the voltage value Vd and smaller than or equal to Vd + H, the currently selected amplification channel is kept unchanged.
Further, the first shielded cable adopts a K3-grade four-core shielded cable special for a nuclear power plant safety-level instrument, and the definition of 4 core wires of the four-core shielded cable is Vm, Vt, VCC and GND;
the second shielded cable adopts the dedicated K3 level two core shielded cable of nuclear power plant's safety level instrument, the definition of 2 heart yearns of two core shielded cables is 24V and 4 ~ 20mA electric current line.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the humidity measuring circuit provided by the invention adopts a measuring circuit realized by all hardware, and the circuit does not contain a digital programmable chip and corresponding measuring software, so that the third-party verification time and identification cost of the software are saved, and the requirement of a safety-level instrument for a nuclear power plant is met.
2. The temperature compensation model in the invention can respectively compensate the low-humidity section and the high-humidity measurement of the humidity sensor, the temperature offset characteristics of different humidity sensors are different, and the correction and compensation of the system error caused by the temperature offset are realized by selecting the precise resistor and finely adjusting the circuit resistance value.
3. The humidity measuring circuit covers a low humidity measuring range and a high humidity measuring range, equal dew point lines of the humidity sensor at different temperatures are obtained by testing output voltage values of the humidity sensor and the temperature sensor output by the primary sampling circuit, and the low humidity measuring range and the high humidity measuring range are respectively fitted by different linear transformation models.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a schematic diagram of a primary loop gas humidity measurement circuit for a high temperature gas cooled reactor according to the present invention.
Fig. 2 is a schematic diagram of a secondary signal conversion circuit according to the present invention.
Fig. 3 is a definition of the shielded cable (4-core) of the present invention.
Fig. 4 is a definition of the shielded cable (2-core) of the present invention.
FIG. 5 is an isometric line of the primary sampling circuit of the hygronom of the present invention.
Reference numbers and corresponding part names:
10-a sensor unit, 11-a primary sampling circuit, 12-a first shielding cable, 13-a secondary signal conversion circuit, 14-a second shielding cable, 20-a linear amplification module, 21-a humidity measurement range selection module, 22-a V/I conversion module and 23-a power supply module.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail so as not to obscure the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, it is to be understood that the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the scope of the present invention.
Example 1
As shown in fig. 1 to 5, a primary loop gas humidity measuring circuit for a high temperature gas cooled reactor according to the present invention includes: the safety level meter comprises a sensor unit 10, a primary sampling circuit 11 and a secondary signal conversion circuit 13, wherein the signal outputs of the primary sampling circuit 11 and the sensor unit 10, the primary sampling circuit 11 and the secondary signal conversion circuit 13 are connected through signal cables with shielding layers meeting the use requirements of a safety level meter;
the sensor unit 10 is arranged in a helium sampling chamber of a primary loop of the high-temperature gas cooled reactor and is in direct contact with helium, the sensor unit 10 is connected to the input end of a primary sampling circuit 11, an output voltage signal of the primary sampling circuit 11 is connected with a secondary signal conversion circuit 13 through a first shielding cable 12 (a four-core cable), the primary sampling circuit 11 is used for carrying out sensor excitation and signal acquisition on the sensor unit 10, an equal dew point curve of the output voltage signal of the sensor unit 10 (namely a humidity sensor and a temperature sensor) is obtained in a standard humidity testing environment, and a low-humidity and high-humidity range humidity calculation transfer function is calculated through the equal dew point curve; the secondary signal conversion circuit 13 uses the humidity calculation transfer mathematical model to realize temperature correction of the humidity measured value through linear conversion and the correlation between the humidity and the temperature; the corrected output current signal is connected to a remote reactor protection system via a second shielded cable 14 (two-core cable).
In this embodiment, the sensor unit 10 includes a humidity sensing element and a temperature sensing element;
the humidity sensing element is a humidity sensor and adopts a capacitance type humidity sensor or a resistance type humidity sensor; the temperature sensing element is a temperature sensor, and the type of the temperature sensor is Pt 100. The humidity sensor and the temperature sensor are simultaneously arranged in the filter cover with the protection function; as close as possible.
The capacitance type humidity sensor adopts oscillation excitation and carries out a signal acquisition mode through F/V conversion, or adopts a sensor excitation and signal acquisition integrated circuit chip.
In this embodiment, the humidity sensor and the temperature sensor are both directly connected to the primary sampling circuit 11, and in order to reduce the distributed capacitance and the lead resistance, the humidity sensor and the temperature sensor are both directly connected to the primary sampling circuit 11 through a lead wire that is as short as possible, and the lead wire is connected to the circuit board of the primary sampling circuit 11 by soldering.
In this embodiment, the primary sampling circuit 11 excites the humidity sensor and the temperature sensor, converts a capacitance value or a resistance value of the humidity sensor into a voltage signal, and converts a resistance value of the temperature sensor into a voltage signal;
the humidity sensor can be excited by adopting an oscillation circuit or an integrated circuit chip, and the capacitance value or the resistance value of the humidity sensor is converted into a voltage value through C/V conversion or F/V conversion; adopting a current source to excite a temperature sensor, and collecting voltage values at two ends of a Pt100 resistor;
the connection of the front-end sensor unit 10 should be as close as possible to the primary sampling circuit board to reduce the distributed capacitance and lead resistance of the sensor leads.
In this embodiment, according to the output signal value of the humidity sensor of the primary sampling circuit 11, the humidity measurement range selection module 21 selects the output voltage value of the low-humidity amplification channel or the high-humidity amplification channel, selects the output of the low-humidity linear amplification channel as the input voltage value of the V/I conversion module 22 when the humidity sensor voltage value is smaller than a certain voltage value Vd, selects the output of the high-humidity linear amplification channel as the input voltage value of the V/I conversion module 22 when the humidity sensor voltage value is greater than Vd + H, where H is a return difference value, and keeps the currently selected amplification channel unchanged when the humidity sensor voltage value is greater than or equal to the voltage value Vd and less than or equal to Vd + H.
In the embodiment, the four-core cable is a K3-grade cable meeting the requirement of the connection of a safety-grade instrument of a nuclear power plant; the two-core cable is a K3-grade cable meeting the requirement of the connection of a safety-grade instrument of a nuclear power plant;
in this embodiment, the secondary signal conversion circuit 13 converts the humidity voltage signal and the temperature voltage signal output by the primary sampling circuit 11, and calculates a current value related to the helium humidity according to the linear conversion and temperature compensation model provided by the present invention. The detailed transformation model and transformation method are described in detail in example 2.
The working principle is as follows: the method is based on the defect that the requirement of a safety-level instrument for a nuclear power plant is not met. The invention designs a primary loop gas humidity measuring circuit for a high-temperature gas cooled reactor, wherein a primary sampling circuit 11 and a secondary signal conversion circuit 13 both adopt a hardware circuit mode, and do not adopt a digital chip and software programming, so that the problems of software code open source and V & V certification are solved. Specifically, the present invention comprises: the sensor unit 10 is arranged in a loop helium gas humidity measurement sampling chamber, and the sensor unit 10 comprises a humidity sensor and a temperature sensor; the primary sampling circuit 11 is used for exciting and collecting signals of the sensor unit 10, the primary sampling circuit 11 is used for obtaining equal dew point curves of output voltage signals of the humidity sensor and the temperature sensor in a standard humidity testing environment, and a low humidity and high humidity range humidity calculation transfer function is calculated through the equal dew point curves; the secondary signal conversion circuit 13 completes signal linear conversion and temperature correction of a humidity calculation mathematical model, the secondary signal conversion circuit 13 is divided into a linear amplification module 20, a humidity measurement range selection module 21, a V/I conversion module 22 and a power supply module 23, when the humidity calculation and temperature correction mathematical model is realized on a hardware circuit, the linear amplification module 20 is divided into a low-humidity amplification channel and a high-humidity amplification channel, each amplification channel is composed of two stages of amplification circuits, and the two stages of amplification modes are adopted to facilitate circuit debugging and precision parameter adjustment.
The humidity measuring circuit and the temperature correcting method for the high-temperature gas cooled reactor are realized in a pure hardware mode, a programmable device and a digital processor are not included in the circuit, software programming and V & V verification are not needed, the identification period and the research and development cost of the safety-level humidity measuring instrument for the nuclear power plant are shortened, and the implementation effect is good.
Example 2
As shown in fig. 1 to 5, the present embodiment is different from embodiment 1 in that fig. 2 is a schematic diagram of a secondary signal conversion circuit 13 according to the present invention; the secondary signal conversion circuit 13 divides the humidity measurement range and realizes the hardware circuit of the temperature compensation model. The secondary signal conversion circuit 13 comprises a linear amplification module 20, a humidity measurement range selection module 21, a V/I conversion module 22 and a power supply module 23 which are connected in sequence;
the linear amplification module 20 is configured to implement linear transformation of signals of the humidity sensor and temperature compensation (implemented by using a linear temperature compensation model) for different humidity measurement ranges; the linear amplification module 20 comprises a low humidity measurement linear amplification channel and a high humidity measurement linear amplification channel;
specifically, the linear temperature compensation model (i.e., the transfer function calculated by calculating the humidity in the low humidity and high humidity ranges from the equal Dew point curve) has a functional relationship of Dew ═ a (k)m*Vt+Vm)+b；
Wherein Dew is the gas humidity Dew point value; ko、kmIs a temperature coefficient; t is a gas temperature value; vt is a temperature sensor signal; vm is the humidity sensor signal; a. b is a linear transfer function correction coefficient.
In order to meet the requirements of measurement accuracy and the simplicity and convenience of circuit debugging, the linear amplification channel circuits in different humidity measurement ranges are divided into two stages of amplification: a first stage of amplification and a second stage of amplification.
The first stage amplification transfer function is:
Vo1＝mo1*Vm+n01vt; vm is the humidity sensor value of the primary sampling circuit 11; vt is the temperature sensor value of the primary sampling circuit 11;mo1、n01is a coefficient;
the transfer function of the second stage amplification is:
Vo2＝mo2*Vo1+n02；Vo1an output value for the first stage amplification;
in the low-humidity measurement range and the high-humidity measurement range, the proportionality coefficient mo1、n01、mo2、n02Are different values.
The measurement range selection module performs logic judgment according to the voltage value of the humidity sensor output by the primary sampling circuit 11, and selects the output value of the low-humidity measurement linear amplification channel or the high-humidity measurement linear amplification channel as the output value of proportional amplification and linear temperature compensation; the coefficients of the two-stage linear amplification of the low-humidity channel and the high-humidity channel are different.
The V/I conversion module 22 is used for converting the voltage value output by the proportional amplification and linear temperature compensation model into a current value in a range of 4-20 mA, and transmitting the current value to a remote reactor protection system through the safety-level second shielding cable 14, wherein the current-voltage conversion can be realized through a current loop or a conversion chip;
the power supply module 23 converts an external input 24VDC voltage into a voltage value required by the operation of the primary sampling circuit 11 and the secondary signal conversion circuit 13, and supplies power to the primary sampling circuit 11 and the secondary signal conversion circuit 13.
Example 3
As shown in fig. 1 to 5, the present embodiment is different from embodiment 1 in that, as shown in fig. 3 and 4, fig. 3 defines a shielded cable (4 cores) of the present invention, and fig. 4 defines a shielded cable (2 cores) of the present invention. Specifically, a core wire definition diagram of a 4-core cable in which the primary sampling circuit 11 is connected to the secondary signal conversion circuit 13 and a 2-core cable in which one end is connected to the secondary signal conversion circuit 13. The 4-core cable and the 2-core cable are K3-grade cables with shielding layers, which meet the requirements of safety-grade instruments of nuclear power plants. The definition of the cable corresponds to the number of wires on the cable core one to one.
The definition of the 4 core wires of the four-core shielded cable is Vm, Vt, VCC and GND;
the definition of the 2 core wires of the two-core shielded cable is 24V and 4-20 mA current wires.
Example 4
As shown in fig. 1 to 5, the present embodiment is different from embodiment 1 in that fig. 5 shows the dew point line of the humidity measuring primary sampling circuit of the present invention.
The primary sampling circuit 11 is matched with the secondary signal conversion circuit 13 to cover the humidity measurement in a low humidity range and a high humidity range; wherein the low humidity range is-20 ℃ dp to +10 ℃ dp, and the high humidity range is 10 ℃ dp to +40 ℃ dp.
Under the environment of standard humidity measurement, the humidity sensor signal and the temperature sensor signal output by the primary sampling circuit 11 are tested, dew point lines of the humidity sensor are obtained by using test data, and a humidity calculation mathematical model is established.
Under the condition that the dew point value of the measurement gas is kept unchanged, the humidity sensor voltage value Vm and the temperature sensor voltage value Vt output by the primary sampling circuit 11 under different gas temperatures are measured, and the correlation between Vm and Vt is drawn in a coordinate system. As can be seen from the equal dew point line, the gas humidity is related to the intercept of the equal dew point line, and the functional relationship between the gas humidity and the intercept is greatly different in the ranges of low humidity (-20 ℃ dp to +10 ℃ dp) and high humidity (10 ℃ dp to +40 ℃ dp). Different linear amplification transfer functions and temperature correction coefficients are used in the low humidity measurement range and the high humidity measurement range respectively.
Therefore, the temperature compensation model in the invention can respectively compensate the low-humidity section and the high-humidity measurement of the humidity sensor, the temperature offset characteristics of different humidity sensors are different, and the correction and compensation of the system error caused by the temperature offset are realized by selecting the precise resistor and finely adjusting the circuit resistance value. The humidity measuring circuit in the invention covers a low humidity measuring range and a high humidity measuring range, equal dew point lines of the humidity sensor at different temperatures are obtained by testing output voltage values of the humidity sensor and the temperature sensor output by the primary sampling circuit 11, and the low humidity measuring range and the high humidity measuring range are respectively fitted by different linear transformation models.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A primary loop gas humidity measuring circuit for a high temperature gas cooled reactor is characterized by comprising: the safety level meter comprises a sensor unit (10), a primary sampling circuit (11) and a secondary signal conversion circuit (13), wherein the primary sampling circuit (11) is connected with the sensor unit (10), the primary sampling circuit (11) is connected with the secondary signal conversion circuit (13), and the signal output of the secondary signal conversion circuit (13) is connected through a signal cable with a shielding layer, which meets the use requirement of a safety level meter;
the sensor unit (10) is arranged in a helium sampling chamber of a primary loop of the high-temperature gas cooled reactor, the sensor unit (10) is connected to the input end of a primary sampling circuit (11), an output voltage signal of the primary sampling circuit (11) is connected with a secondary signal conversion circuit (13) through a first shielding cable (12), the primary sampling circuit (11) carries out sensor excitation and signal acquisition on the sensor unit (10), an equal dew point curve of the output voltage signal of the sensor unit (10) is obtained in a standard humidity testing environment, and a low-humidity and high-humidity range humidity calculation transfer function is calculated through the equal dew point curve; the secondary signal conversion circuit (13) utilizes the humidity calculation transfer mathematical model to realize temperature correction of a humidity measured value through linear conversion and the correlation between humidity and temperature; the corrected output current signal is connected with a remote reactor protection system through a second shielded cable (14).
2. The primary loop gas humidity measuring circuit for the high temperature gas cooled reactor as claimed in claim 1, wherein the sensor unit (10) comprises a humidity sensing element and a temperature sensing element;
the humidity sensing element is a humidity sensor and adopts a capacitance type humidity sensor or a resistance type humidity sensor; the temperature sensing element is a temperature sensor, and the type of the temperature sensor is Pt 100.
3. The primary loop gas humidity measuring circuit for the high-temperature gas cooled reactor as claimed in claim 2, wherein the humidity sensor and the temperature sensor are both directly connected with the primary sampling circuit (11) through leads, and the leads are connected with a circuit board of the primary sampling circuit (11) in a soldering manner.
4. The primary loop gas humidity measuring circuit for the high temperature gas cooled reactor as claimed in claim 2, wherein the primary sampling circuit (11) activates the humidity sensor and the temperature sensor, converts a capacitance value or a resistance value of the humidity sensor into a voltage signal, and converts a resistance value of the temperature sensor into a voltage signal;
the excitation mode of the capacitance type humidity sensor comprises the following steps: adopting a mode of exciting an oscillating circuit and adding F/V or C/V conversion; adopting a capacitance value or resistance value measurement integrated chip to directly convert the capacitance value or the resistance value of the humidity sensor into a voltage signal;
the resistance type temperature sensor is excited by adopting a constant current source to output constant current to the sensor and collecting the voltage at two ends of the sensor.
5. The primary loop gas humidity measurement circuit for the high-temperature gas cooled reactor as recited in claim 2, wherein the secondary signal conversion circuit (13) comprises a linear amplification module (20), a humidity measurement range selection module (21), a V/I conversion module (22) and a power supply module (23) which are connected in sequence;
the linear amplification module (20) is used for realizing linear transformation of humidity sensor signals and temperature compensation of different humidity measurement ranges; the linear amplification module (20) comprises a low-humidity measurement linear amplification channel and a high-humidity measurement linear amplification channel;
the measurement range selection module (21) performs logic judgment according to the voltage value of the humidity sensor output by the primary sampling circuit (11), and selects the output value of the low-humidity measurement linear amplification channel or the high-humidity measurement linear amplification channel as the output value of proportional amplification and linear temperature compensation;
the V/I conversion module (22) is used for converting the voltage value output by the proportional amplification and linear temperature compensation model into a current value in a range of 4-20 mA, and transmitting the current value to a remote reactor protection system through a safety-level second shielding cable;
the power supply module (23) converts an external input 24VDC voltage into a voltage value required by the operation of the primary sampling circuit (11) and the secondary signal conversion circuit (13) so as to supply power to the primary sampling circuit and the secondary signal conversion circuit.
6. The primary loop gas humidity measurement circuit for a high temperature gas cooled reactor as set forth in claim 5, wherein the linear temperature compensation model has a functional relationship of Dew ═ a (k ═ a)mVt + Vm) + b; wherein Dew is the gas humidity Dew point value; k is a radical ofmIs the temperature coefficient; vt is a temperature sensor signal; vm is the humidity sensor signal; a. b is a linear transfer function correction coefficient.
7. The primary loop gas humidity measurement circuit for the high temperature gas cooled reactor as claimed in claim 6, wherein the linear temperature compensation model comprises a first stage amplification and a second stage amplification, wherein:
the first stage amplification transfer function is:
Vo1＝mo1*Vm+n01vt; vm is the humidity sensor value of the primary sampling circuit (11); vt is a temperature sensor value of the primary sampling circuit (11); m iso1、n01Is a coefficient;
the transfer function of the second stage amplification is:
Vo2＝mo2*Vo1+n02；Vo1an output value for the first stage amplification;
in the low-humidity measurement range and the high-humidity measurement range, the proportionality coefficient mo1、n01、mo2、n02Are different values.
8. The primary loop gas humidity measuring circuit for high temperature gas cooled reactor as claimed in claim 5, wherein the humidity measuring range selecting module (21) selects the output voltage value of the low humidity amplifying channel or the high humidity amplifying channel according to the humidity sensor output signal value of the primary sampling circuit (11), when the humidity sensor voltage value is less than a certain voltage value Vd, the output of the low humidity linear amplifying channel is selected as the input voltage value of the V/I conversion module, when the humidity sensor voltage value is greater than Vd + H, where H is the return difference value, the output of the high humidity linear amplifying channel is selected as the input voltage value of the V/I conversion module, and when the humidity sensor voltage value is greater than or equal to the voltage value Vd and less than or equal to Vd + H, the currently selected amplifying channel is kept unchanged.
9. The primary loop gas humidity measuring circuit for the high-temperature gas cooled reactor according to claim 1, wherein the primary sampling circuit (11) and the secondary signal conversion circuit (13) are matched to cover humidity measurement in a low humidity range and a high humidity range; wherein the low humidity range is-20 ℃ dp to +10 ℃ dp, and the high humidity range is 10 ℃ dp to +40 ℃ dp.
10. The primary loop gas humidity measurement circuit for the high-temperature gas cooled reactor as claimed in claim 1, wherein the first shielded cable (12) is a K3 grade four-core shielded cable dedicated to nuclear power plant safety level instruments, and the definition of 4 cores of the four-core shielded cable (12) is Vm, Vt, VCC and GND;
the second shielded cable (14) adopts a K3-grade two-core shielded cable special for a safety-level instrument of a nuclear power plant, and the definition of 2 core wires of the two-core shielded cable (14) is 24V and 4-20 mA current wires.
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Cited By (1)
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| CN113465763A (en) * | 2021-07-15 | 2021-10-01 | 中国电子科技集团公司第四十九研究所 | Temperature and humidity sensor and temperature and humidity measuring method |
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| CN112863713B (en) | 2022-02-11 |
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