A water level error correction system and method for steam generators

Abstract

This invention discloses a water level error correction system and method for steam generators, belonging to the field of industrial measurement and control. The system includes a differential pressure sensor with a Wheatstone bridge as its core, a precision resistor connected in series in its power supply circuit, and a multi-channel signal acquisition and processing unit. The method simultaneously acquires the output voltages of the two channels of the bridge and the voltage of the precision resistor, first calculating the sensor chip temperature; then constructing two characteristic quantities—voltage and voltage difference—and intelligently judging the system operating condition based on their changes; finally, adaptively calling a pre-stored compensation model according to the operating condition, calculating the system static pressure, and performing comprehensive dynamic correction of the original differential pressure for static pressure error and temperature drift, thereby calculating the accurate water level. This invention eliminates the need for additional sensors, achieving real-time compensation for the inherent error of the differential pressure sensor under all operating conditions solely through innovative signal fusion and adaptive algorithms, significantly improving the accuracy and stability of water level measurement, while also being low in cost and simple in structure.

Description

Technical Field

[0001] This invention belongs to the field of industrial measurement and control technology, specifically relating to a water level error correction system and method for steam generators. Background Technology

[0002] A steam generator is a key thermal equipment that uses energy sources such as fuel combustion or electricity to heat water and produce steam or saturated steam. The steam it generates is widely used in continuous industrial production processes in chemical, pharmaceutical, textile, food processing, and civilian explosives (such as emulsion explosives), providing the necessary thermal energy and working fluid for processes such as reaction, sterilization, humidification, and power drive. The safe, efficient, and stable operation of the steam generator directly affects the continuity of the production system, product quality, and overall energy consumption level.

[0003] Traditional steam generators primarily use fossil fuels (such as coal, natural gas, and oil) as their energy source. They are complex in structure, bulky, and generate emissions from combustion products. In recent years, with the global energy structure transformation and the increasing demand for industrial automation and cleaner energy, electric steam generators have rapidly emerged and are widely used. Electric steam generators employ electrothermal conversion methods such as resistance or electromagnetic induction, offering numerous advantages including compact structure, small size, rapid start-up, agile response, heat generation upon power connection, zero emissions, clean and environmentally friendly operation, precise control, and ease of automation. Therefore, electric steam generators are gradually replacing traditional fuel-based equipment in small-to-medium scale steam consumption scenarios, cleanrooms, experimental platforms, and industrial processes with stringent requirements for control response speed.

[0004] However, electric steam generators also face unique technical challenges during operation, with the accurate measurement of their internal water level being particularly prominent. Water level is a core parameter for the safe operation of a steam generator; excessively high water levels can lead to water carryover in the steam, affecting subsequent processes and equipment safety; excessively low water levels may cause dry burning, overheating damage to heating elements, or even explosion risks. Due to their compact structure and drastic operating conditions (especially frequent start-stops and rapid power adjustments), electric steam generators experience rapid dynamic fluctuations in internal pressure (static pressure), posing a severe challenge to existing water level measurement systems. Currently widely used non-invasive water level measurement methods primarily measure the water pressure difference ΔP in the steam generator's pressure channel and convert it to water level height by combining it with the medium density. This type of technology can be found in Chinese patent CN202410701177.8. The accuracy of this method essentially depends on the accuracy of the differential pressure transmitter's output signal. Ordinary differential pressure sensors have two inherent errors in actual operation: (1) Static pressure error: The zero-point output of the sensor shifts nonlinearly as the static pressure of the system increases, and this shift fluctuates during the dynamic change of static pressure; (2) Temperature drift: The sensor sensitivity and zero point are affected by the ambient and medium temperature, resulting in output drift that changes with temperature. Under the typical operating conditions of frequent start-stop and rapid power response of electric steam generators, the static pressure and differential pressure of the system are often in a state of drastic change, which causes serious distortion of the output signal of conventional differential pressure transmitters, and in turn causes large fluctuations and jumps in water level indication, which not only seriously interferes with the stability of the automatic control system, but also creates hidden dangers for operation safety.

[0005] To improve accuracy, existing technologies mainly employ two approaches: one is to use low hydrostatic error sensors with special packaging processes such as "silicon-on-silicon" stacking, but this is costly and offers limited accuracy improvement; the other is to add an independent hydrostatic sensor to the system for dual-sensor compensation, which can improve accuracy but significantly increases system complexity and overall cost. Neither of these solutions is widely applicable in cost-sensitive and demanding electric steam generator applications.

[0006] Therefore, achieving accurate measurement of differential pressure from differential pressure sensors without significantly increasing hardware costs and system complexity has become a key technical bottleneck for improving the reliability of water level measurement in electric steam generators and ensuring their safe and efficient operation. In view of this, this invention is proposed. Summary of the Invention

[0007] In view of the above-mentioned problems in the prior art, the present invention proposes a water level error correction system and method for steam generators, aiming to solve at least one of the above problems.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0009] A water level error correction system for a steam generator, comprising:

[0010] A differential pressure sensor is installed on the pressure-inlet pipe of the steam generator to sense the differential pressure caused by changes in the water level inside the steam generator. The differential pressure sensor uses a Wheatstone bridge as its core sensing unit.

[0011] Low-temperature drift precision resistor R o The low-temperature drift precision resistor R o It is connected in series in the power supply circuit of the Wheatstone bridge;

[0012] The signal acquisition module is used to acquire multiple electrical signals related to the differential pressure sensor in real time, and it includes at least:

[0013] The first voltage detection module is used to detect the voltage V1(t) between the positive output terminal OUT+ of the Wheatstone bridge and the negative input terminal IN- of the power supply.

[0014] The second voltage detection module is used to detect the voltage V2(t) between the negative output terminal OUT- of the Wheatstone bridge and the negative input terminal IN- of the power supply.

[0015] The third voltage detection module is used to detect the low-temperature drift precision resistor R. o The voltage V3(t) across the terminals at time t;

[0016] The signal processing unit processes the acquired multiple electrical signals, intelligently identifies the operating conditions of the steam generator, and obtains the error-corrected true differential pressure value DP based on these conditions. c (t), thus obtaining the water level after error correction.

[0017] A method for correcting water level errors in a steam generator, comprising the following steps:

[0018] Step S1: After the steam generator is put into operation, the signal acquisition module is used to synchronously acquire multiple electrical signals related to the differential pressure sensor in real time.

[0019] Step S2: Based on the digital signal of the electrical signal obtained in step S1, calculate the real-time temperature T(t) of the sensor chip at the current moment;

[0020] Step S3: Process the multiple electrical signals obtained in step S1 to obtain the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) associated with the voltages V1(t), V2(t), and V3(t);

[0021] Step S4: Based on the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) calculated in step S3, perform multi-condition fusion judgment to identify the current operating condition of the water level error correction system; if it is an abnormal operating condition, directly activate the preset safety processing procedure, end the subsequent calculation, and wait for the system to return to normal; if it is a steady-state operating condition or a dynamic operating condition, proceed to the next step to perform accurate compensation calculation.

[0022] Step S5: Based on the operating condition flags output in step S4, adaptively retrieve the set of compensation coefficients and calculation models that precisely match the corresponding operating conditions from the memory storage, perform accurate calculation of static pressure and differential pressure at the differential pressure sensor, and finally calculate the water level after error correction.

[0023] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0024] 1. This invention innovatively achieves direct and accurate inversion of the sensor chip temperature by acquiring multiple raw voltage signals from the Wheatstone bridge of the differential pressure sensor. It cleverly constructs two characteristic quantities—voltage and voltage difference—to decouple the core information containing static pressure and differential pressure. Through intelligent operating condition judgment based on massive full-condition calibration data, the system can adaptively call the optimal compensation model to perform real-time and dynamic comprehensive correction of static pressure error and temperature drift. This method fundamentally overcomes the industry problem of output distortion and large fluctuations in water level readings caused by traditional differential pressure sensors during dynamic processes such as steam generator start-up and shutdown, and rapid load changes, ensuring measurement accuracy and stability throughout the entire process from cold start-up, stable operation to transient conditions.

[0025] 2. The core advantage of this invention lies in its ingenious signal processing algorithm, rather than relying on expensive hardware. Hardware-wise, it only requires connecting an external low-temperature drift precision resistor in series in the power supply circuit of a general differential pressure sensor, and adding a corresponding voltage acquisition and processing channel. Compared to traditional high-precision solutions that use high-cost special low static pressure error sensors such as "silicon-on-silicon" sensors, or add an additional independent static pressure sensor, this invention achieves comparable or even better compensation effects at extremely low marginal hardware costs. The system structure is simple, highly reliable, and easy to promote and apply on a large scale in the cost-sensitive field of electric steam generators.

[0026] 3. The system employs a hardware comparator to quickly extract voltage changes, combined with efficient software algorithms for multi-threshold fusion judgment, enabling rapid and accurate identification of the system's steady-state, dynamic, or abnormal operating conditions. Based on this condition indicator, the system adaptively switches to the pre-stored optimal compensation model within milliseconds, achieving closed-loop intelligent control of "sensing-judgment-compensation." This hierarchical (temperature first, then pressure) progressive judgment logic and rapid anomaly response mechanism not only ensure timely compensation but also greatly enhance the autonomous decision-making capability and operational safety of the entire water level measurement system in the face of complex operating conditions. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the steam generator used in this invention;

[0029] Figure 2 This is a schematic diagram of the measurement principle of the water level error correction system of the present invention;

[0030] Figure 3 This is a schematic diagram of the comparative processing principle of the water level error correction system of the present invention;

[0031] The meanings of the reference numerals in the attached figures are as follows:

[0032] 1-Water inlet pipe, 2-Steam pipe, 3-Differential pressure sensor, 100-Steam generator, 200-Wheatstone bridge. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0034] like Figures 1 to 3 As shown, the present invention provides a water level error correction system for a steam generator, comprising:

[0035] A differential pressure sensor 3 is installed on the pressure-sensing pipe of the steam generator 100 to sense the pressure difference caused by changes in the water level within the steam generator 100. Specifically, the steam generator 100 has two pressure-sensing ports, corresponding to the steam space at the top and the water space at the bottom, respectively. The pressure-sensing port corresponding to the steam space is connected to a condensing container outside the steam generator 100 via a first pressure-sensing pipe, and the pressure-sensing port corresponding to the water space is connected to the condensing container via a second pressure-sensing pipe. The differential pressure sensor 3 is installed on the second pressure-sensing pipe, and the first and second pressure-sensing pipes together constitute the pressure-sensing pipe. The differential pressure sensor 3 uses a Wheatstone bridge 200 as its core sensing unit. Figure 2 As shown, the Wheatstone bridge 200 consists of four varistors, which are denoted as R1, R2, R3 and R4 respectively (the four varistors are integrated on a single-crystal silicon sensitive chip through MEMS technology). Among them, R1 and R3 are located in one pair of opposite arms of the bridge, and their resistance changes in the same direction (both increasing or decreasing). R2 and R4 are located in another pair of opposite arms of the bridge, and their resistance changes in the same direction but opposite to that of R1 and R3. Specifically, the Wheatstone bridge 200 uses a constant voltage power supply Vcc to provide a stable DC excitation voltage. The positive input terminal IN+ of the bridge is connected to the constant voltage power supply Vcc, and the negative input terminal IN- of the bridge is connected to the zero-voltage reference point GND (e.g., ground). The bridge has a positive output terminal OUT+ and a negative output terminal OUT-. The positive input terminal IN+ and the positive output terminal OUT+ are connected to form the first bridge arm, the positive output terminal OUT+ and the negative input terminal IN- are connected to form the second bridge arm, the negative output terminal OUT- and the negative input terminal IN- are connected to form the third bridge arm, and the positive input terminal IN+ and the negative output terminal OUT- are connected to form the fourth bridge arm. Four varistors R1, R2, R3 and R4 are connected to the first, second, third and fourth bridge arms respectively.

[0036] Low-temperature drift precision resistor R o The low-temperature drift precision resistor R o In series in the power supply circuit of the Wheatstone bridge 200, specifically connected between the negative input terminal IN- and the zero-current reference point GND. In a preferred embodiment, the cryogenic drift precision resistor R o Installed on the outside of the pressure-sensing pipe or in another location unaffected by the temperature of the measured medium, it is not integrated onto the single-crystal silicon sensing chip where the Wheatstone Bridge 200 is located. Considering that the resistance value itself changes with temperature, even with low-temperature drift, the precision resistor R... oIts temperature coefficient is low; if integrated onto a chip, its resistance will still drift due to the chip's operating temperature, thus interfering with measurement accuracy. If R is insisted upon... o Integrating it onto a chip and achieving extremely low temperature drift requires a more complex and costly high-stability resistor process. Therefore, this embodiment will use R... o By placing it externally in a location far from temperature-sensitive areas, it can effectively suppress resistance changes caused by temperature and avoid the increased process difficulty and cost brought about by chip integration, thus ensuring accuracy while being more practical and economical.

[0037] The signal acquisition module is used to acquire multiple electrical signals related to the differential pressure sensor 3 in real time, and it includes at least:

[0038] The first voltage detection module is used to detect the voltage V1(t) between the positive output terminal OUT+ and the negative input terminal IN- of the Wheatstone bridge 200 (that is, the voltage across R2 at time t).

[0039] The second voltage detection module is used to detect the voltage V2(t) between the negative output terminal OUT- and the negative input terminal IN- of the Wheatstone bridge 200 (that is, the voltage across R3 at time t); it should be understood that the first voltage detection module can also detect the voltage across R1, in which case the second voltage detection module detects the voltage across R4.

[0040] The third voltage detection module is used to detect the low-temperature drift precision resistor R. o The voltage V3(t) across the terminals at time t.

[0041] The signal processing unit processes the acquired multiple electrical signals, intelligently identifies the operating conditions of the steam generator, and obtains the error-corrected true differential pressure value DP based on these conditions. c (t), thus obtaining the water level after error correction (the specific processing method will be introduced later, and will not be repeated here).

[0042] In a preferred embodiment, the signal processing unit includes an analog-to-digital conversion module, which comprises three independent A / D conversion circuits, namely... Figure 3The first, second, and third A / D conversion circuits shown correspond to the first, second, and third voltage detection modules, respectively, and are used to convert the corresponding electrical signals into digital signals. Furthermore, a comparator group is included, comprising a first, second, and third comparator, used to compare the digital signals of voltages V1(t), V2(t), and V3(t) at different times, and extract the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) within a predetermined time interval (the predetermined time interval is Δt, such as 1s, 5s, 10s, or other time intervals). Further, a memory storage device is included to store historically acquired voltage signals, pre-calibrated calculation models, etc., and facilitate retrieval by the comparator group and the MCU processor. It should be understood that an MCU processor is also included, used to receive the digital signals from the analog-to-digital conversion module and the voltage changes output by the comparator group, and to perform temperature calculation, static pressure estimation, differential pressure compensation, and water level calculation.

[0043] In some embodiments, a communication module may also be provided, which is connected to the MCU processor to feed back information such as temperature, static pressure, pressure difference and water level obtained by the MCU processor to remote servers, computers and other devices.

[0044] Based on the above-mentioned water level error correction system for steam generators, this invention also relates to a water level error correction method for steam generators. This method acquires multiple voltage signals and their changes related to the differential pressure sensor 3, performs fusion processing and operating condition judgment, and adaptively selects a compensation mode to achieve real-time dynamic correction of static pressure error and temperature drift. The method includes the following steps:

[0045] Step S1: Real-time data acquisition and preprocessing

[0046] After the steam generator 100 is put into operation, the signal acquisition module is used to synchronously acquire multiple electrical signals related to the differential pressure sensor 3 in real time. This includes acquiring three analog voltage signals V1(t), V2(t), and V3(t) through the first voltage detection module, the second voltage detection module, and the third voltage detection module, and then converting the voltage signals into digital signals using the analog-to-digital conversion module of the signal processing unit.

[0047] Step S2: Temperature calculation of differential pressure sensor 3 chip

[0048] Based on the digital signal of the voltage signal V3(t) obtained in step S1, the temperature calibration model pre-stored in memory is invoked to calculate the real-time temperature T(t) of the sensor's sensitive chip at the current moment:

[0049] ;

[0050] Where f() represents the temperature fitting function;

[0051] In an exemplary embodiment, the temperature calibration model used to calculate the real-time temperature T(t) can be expressed as:

[0052] ;

[0053] Wherein, coefficients a0, a1, and a2 are constants determined through full-temperature-range calibration before leaving the factory. (It should be noted that this temperature calibration model is a parameter model obtained by fitting actual test and calibration data before leaving the factory. It is an empirical formula that does not consider strict physical dimensions. Its specific form can be adjusted according to the characteristics of the selected sensor, the calibration accuracy requirements, and the fitting effect. The above quadratic polynomial expression is only an example and not the only implementation method. The coefficients can also form a set of coefficients, and different combinations of coefficients are used for different situations. The static pressure calculation model in the following text is similar and will not be repeated.)

[0054] It should be noted that due to the low temperature drift of the precision resistor R o It is connected in series in the power supply circuit of the Wheatstone bridge 200. The Wheatstone bridge 200 can be equivalent to an equivalent resistance R whose resistance varies with temperature. L Due to the low temperature drift of the precision resistor R o Installed on the outside of the pressure-sensing pipeline or in another location unaffected by the temperature of the measured medium, its resistance remains essentially constant regardless of the high-temperature medium in the steam generator. Because the voltage provided by the constant-voltage power supply Vcc is stable, when the equivalent resistance R... L When the resistance value changes with the temperature of the detected medium, i.e., the real-time temperature T(t), V3(t) will change accordingly. Therefore, by obtaining and fitting V3(t), the real-time temperature T(t) of the medium detected by the differential pressure sensor 3 can be accurately obtained.

[0055] Step S3: Calculation of voltage change rate

[0056] The comparator group compares the digitized voltage signal at the current time t with the previous time (specifically, time t-Δt, which differs from time t by a predetermined time interval Δt), and extracts the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) within the predetermined time interval; the mathematical expression is:

[0057] ΔV1(t) = V1(t) - V1(t - Δt);

[0058] ΔV2(t) = V2(t) - V2(t - Δt);

[0059] ΔV3(t)=V3(t)-V3(t - Δt);

[0060] Since the voltage change amounts ΔV1(t), ΔV2(t), and ΔV3(t) reflect the voltage changes within a predetermined time interval Δt, therefore, in essence, they also represent the corresponding voltage change rates;

[0061] Step S4, Intelligent Identification and Judgment of Operating Conditions

[0062] Based on the voltage change amounts ΔV1(t), ΔV2(t), and ΔV3(t) calculated in step S3, call the threshold parameters pre - stored in the memory to perform multi - condition fusion judgment to identify the current operating condition of the system; the threshold parameters include: the threshold Hp for judging pressure - related dynamics, the threshold Ht for judging abnormal temperature states, and the global threshold Ha for identifying abnormal pressure signals. The judgment logic is as follows:

[0063] First, judge the temperature state. If |ΔV3(t)| < Ht, then determine that the temperature state is normal; otherwise, determine that the temperature state is abnormal and directly mark it as an abnormal operating condition;

[0064] Next, when the temperature state is normal, judge the pressure operating condition based on ΔV1(t) and ΔV2(t). Specifically, if both |ΔV1(t)| < Hp and |ΔV2(t)| < Hp and this state has lasted for more than the preset stable duration T_st (e.g., 30 seconds), then determine it as a steady - state operating condition; if |ΔV1(t)| ≥ Hp or |ΔV2(t)| ≥ Hp, and |ΔV1(t)| < Ha and |ΔV2(t)| < Ha, then determine it as a dynamic operating condition; among them, the dynamic operating condition may also include sub - operating conditions such as the startup phase, load - rising operating condition, load - falling operating condition, etc.; if |ΔV1(t)| ≥ Ha or |ΔV2(t)| ≥ Ha, then determine it as an abnormal operating condition;

[0065] Next, based on the determined operating condition, output a digital flag for representing the current operating condition (steady - state operating condition, dynamic operating condition, abnormal operating condition, etc.); if it is an abnormal operating condition, directly enable the preset safety handling procedures, including but not limited to triggering an audible and visual alarm, locking the water level output to a safe value or the previous valid value, recording the abnormal event log, ending the subsequent calculation, and waiting for the system to return to normal; if it is a steady - state operating condition or a dynamic operating condition, enter the next step for precise compensation calculation;

[0066] Step S5, Static Pressure and Differential Pressure Calculation and Error Correction

[0067] This step is executed only when step S4 determines the operating condition to be either steady-state or dynamic. Based on the operating condition flag output in step S4, the MCU processor adaptively retrieves the set of compensation coefficients and calculation model precisely matched to the corresponding operating condition from memory to perform accurate calculations of static pressure and differential pressure; specifically, this includes:

[0068] S51. Calculation of voltage combination quantities:

[0069] Calculate two key characteristic voltage quantities as the basis for subsequent static pressure and differential pressure calculations:

[0070] ;

[0071] ;

[0072] in, This represents the algebraic sum of the voltages of the two output branches of the Wheatstone bridge 200. This voltage sum signal contains the main information about the static pressure applied to the sensor, and its amplitude is also affected by the chip temperature. This represents the algebraic difference between the voltages of the two output branches of the Wheatstone bridge. This voltage difference directly corresponds to the original differential pressure sensed by the sensor, but it is also affected by the cross-effects of hydrostatic pressure (hydrostatic error) and chip temperature (temperature drift). By constructing these two combined signals, the sensor's original output is decoupled into characteristic quantities that are more directly related to hydrostatic pressure and differential pressure, respectively, laying the foundation for subsequent independent and targeted error compensation.

[0073] S52, Compensation Model and Coefficient Call

[0074] The system memory stores multiple sets of compensation coefficients calibrated for different operating conditions. For example, the operating conditions include steady-state operating conditions, startup operating conditions, load increase operating conditions, load decrease operating conditions, etc., and each operating condition corresponds to an independent set of compensation coefficients. The MCU processor automatically selects and calls the set of coefficients that best matches the current operating condition according to the current operating condition flag output in step S4 for subsequent calculations.

[0075] S53, Static Pressure (SP) Calculation

[0076] Based on voltage and signal Using the real-time temperature T(t) of the sensor chip obtained in step S2, the static pressure calibration model pre-stored in memory and matched to the current operating conditions is called to calculate the current system static pressure SP(t) acting on the differential pressure sensor 3. The static pressure calibration model has the following independent variable: The multivariate function of T(t) is determined through full-condition calibration experiments before leaving the factory, and its specific form is selected according to the optimization of the operating conditions.

[0077] For any given operating condition indicator k, the general formula for its calculation is:

[0078] ;

[0079] Where SP(t) represents the system static pressure at time t, f sp () represents the static pressure calculation function, and the superscript (k) represents the working condition k (e.g., steady state, dynamic state, etc.).

[0080] Example of the correspondence between operating conditions and static pressure calibration models:

[0081] Under steady-state conditions, a high-precision polynomial model is employed, with coefficients obtained through long-term steady-state calibration to ensure optimal accuracy in a stable state.

[0082] ,

[0083] in, These are a specific set of coefficients calibrated under steady-state conditions;

[0084] For dynamic operating conditions (such as startup or load changes), the calculation formula may need to include more terms to describe the nonlinear and coupling effects in the rapidly changing process, for example:

[0085]

[0086] in, These are another set of specific coefficients obtained under dynamic operating conditions;

[0087] The memory storage independently stores a set of coefficients and corresponding calculation formula structure information for each working condition. During calculation, the corresponding coefficients and calculation process are called according to the working condition flag k.

[0088] S54. Calculation and Comprehensive Error Correction of Pressure Difference (DP) for Adaptive Operating Conditions:

[0089] The differential pressure (DP) and the differential pressure sensor 3 are the voltage difference. The real-time temperature T(t) and static pressure SP(t) are related. Therefore, this step combines another set of coefficients corresponding to the current operating condition k (used to calculate the pressure difference) to perform comprehensive error compensation and calculate a high-precision true pressure difference value DP. c (t), whose general formula is:

[0090] ;

[0091] Among them, DP c (t) represents the actual pressure difference value. This represents the differential pressure calculation and comprehensive error correction function corresponding to operating condition k. This function aims to compensate for the influence of temperature drift and static pressure error on the original differential pressure signal. Its specific form and coefficients are also determined by calibration experiments for each operating condition.

[0092] For steady-state conditions, the actual pressure difference DP c The formula for calculating (t) is shown below as an example:

[0093] ;

[0094] in, It is the differential pressure correction factor under steady-state operating conditions;

[0095] For dynamic operating conditions, the actual differential pressure value DP c The formula for calculating (t) is shown below as an example:

[0096]

[0097] in, It is the differential pressure correction factor under dynamic operating conditions.

[0098] S55, Calculation of Actual Water Level in Steam Generator

[0099] The actual water level h(t) of the steam generator is calculated using the following formula:

[0100]

[0101] in, The density of water in the pressure-sensing pipe is represented by a table lookup method, which is based on the real-time measured chip temperature T(t) and the calculated static pressure SP(t). The steam density inside the steam generator 100 is saturated steam density. The density of the feedwater in the feedwater descending channel of the steam generator 100 is given by the fact that obtaining these two densities requires the acquisition and calculation of corresponding parameters in the water inlet pipe 1, steam pipe 2, and steam generator 100, which is existing technology and will not be described in detail here; g is the acceleration due to gravity; H is the height difference between the two pressure tapping ports on the body of the steam generator 100; L is the vertical height from the corresponding pressure tapping port in the water space to the top steam outlet.

[0102] In addition, the pre-calibration of the computational model has been completed before the system leaves the factory, and the calibration method is exemplified as follows (it should be understood that this is only a partial test):

[0103] Under certain temperature conditions, the output data of differential pressure sensor 3 under different differential pressure conditions are summarized in Table 1; and the output data of differential pressure sensor 3 under different static pressure conditions are summarized in Table 2.

[0104] Table 1. Differential pressure sensor output data under different differential pressure conditions

[0105]

[0106] Table 2 Sensor output data at different static pressures

[0107]

[0108] Note: V 10 V 20 The output values ​​of V1 and V2 are given when the input differential pressure and static pressure are both 0. In Tables 1 and 2, these are represented as (V1 + V2) - (V...). 10 +V 20 This expresses the change in (V1+V2) of the differential pressure sensor when it is subjected to different static pressures.

[0109] By using the principle test data shown in Tables 1 and 2, and employing a similar method to collect a complete calibration dataset across the entire temperature range, static pressure range, and differential pressure range for multivariate nonlinear regression analysis, the specific mathematical forms of the static pressure calculation function and the actual differential pressure calculation function under each working condition, as well as their optimal coefficient set, can be determined. These function models and coefficients constitute the core compensation knowledge base of the system, which is pre-set and permanently stored in the memory.

[0110] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A water level error correction system for a steam generator, characterized in that, It includes: A differential pressure sensor (3) is installed on the pressure-sensing pipe of the steam generator (100) to sense the differential pressure caused by the change in water level inside the steam generator (100). The differential pressure sensor (3) uses a Wheatstone bridge (200) as its core sensing unit. The Wheatstone bridge (200) uses a constant voltage power supply Vcc to provide a stable DC excitation voltage. The positive input terminal IN+ of the power supply of the bridge is connected to the constant voltage power supply Vcc, and the negative input terminal IN- of the power supply of the bridge is connected to the zero reference point GND. The bridge has a positive output terminal OUT+ and a negative output terminal OUT-. The positive input terminal IN+ and the positive output terminal OUT+ of the bridge are connected. The first bridge arm is formed by connecting the positive output terminal OUT+ of the bridge and the negative input terminal IN- of the power supply. The second bridge arm is formed by connecting the negative output terminal OUT- of the bridge and the negative input terminal IN- of the power supply. The third bridge arm is formed by connecting the positive input terminal IN+ of the power supply and the negative output terminal OUT- of the bridge. The fourth bridge arm is formed by connecting the positive input terminal IN+ of the power supply and the negative output terminal OUT- of the bridge. The Wheatstone bridge (200) is composed of four varistors, which are denoted as R1, R2, R3 and R4 respectively, and are connected to the first, second, third and fourth bridge arms respectively. R1 and R3 are located in one pair of opposite bridge arms of the bridge, and their resistance changes in the same direction. R2 and R4 are located in another pair of opposite bridge arms of the bridge, and their resistance changes in the same direction but opposite to that of R1 and R3. Low-temperature drift precision resistor R o The low-temperature drift precision resistor R o The cryogenic precision resistor R is connected in series in the power supply circuit of the Wheatstone bridge (200) and between the negative input terminal IN- and the zero-current reference point GND. o Installed on the outside of the pressure tapping pipe or in other installation locations not directly affected by the temperature of the measured medium; The signal acquisition module is used to acquire multiple electrical signals related to the differential pressure sensor (3) in real time, and includes at least: a first voltage detection module for detecting the voltage V1(t) between the positive output terminal OUT+ and the negative input terminal IN- of the Wheatstone bridge (200); a second voltage detection module for detecting the voltage V2(t) between the negative output terminal OUT- and the negative input terminal IN- of the Wheatstone bridge (200); and a third voltage detection module for detecting the low-temperature drift precision resistor R. o The voltage V3(t) across the terminals at time t; The signal processing unit processes the acquired multiple electrical signals, intelligently identifies the operating conditions of the steam generator, and obtains the error-corrected true differential pressure value DP based on these conditions. c (t), thus obtaining the water level after error correction.

2. The water level error correction system for a steam generator as described in claim 1, characterized in that, The signal processing unit includes an analog-to-digital conversion module, a comparator group, a memory storage unit, and an MCU processor. The analog-to-digital conversion module includes a first A / D conversion circuit, a second A / D conversion circuit, and a third A / D conversion circuit, which correspond to the first voltage detection module, the second voltage detection module, and the third voltage detection module, respectively, and are used to convert the corresponding electrical signals into digital signals. The comparator group includes a first, second, and third comparator, which are used to compare the digital signals of voltages V1(t), V2(t), and V3(t) at different times, respectively, and extract the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) within a predetermined time interval. The memory storage unit stores historically acquired voltage signals and pre-calibrated calculation models, facilitating retrieval by the comparator group and the MCU processor. The MCU processor receives the digital signals from the analog-to-digital conversion module and the voltage changes output by the comparator group, and performs temperature calculation, static pressure estimation, differential pressure compensation, and water level calculation.

3. A method for correcting water level errors in a steam generator, implemented using the water level error correction system described in claim 2, characterized in that... The water level error correction method includes the following steps: Step S1: After the steam generator (100) is put into operation, the signal acquisition module is used to synchronously acquire multiple electrical signals related to the differential pressure sensor (3) in real time. Step S2: Based on the digital signal of the electrical signal obtained in step S1, calculate the real-time temperature T(t) of the sensor chip at the current moment; Step S3: Process the multiple electrical signals obtained in step S1 to obtain the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) associated with the voltages V1(t), V2(t), and V3(t); Step S4: Based on the voltage changes ΔV1(t), ΔV2(t), and ΔV3(t) calculated in step S3, perform multi-condition fusion judgment to identify the current operating condition of the water level error correction system; if it is an abnormal operating condition, directly activate the preset safety processing procedure, end the subsequent calculation, and wait for the system to return to normal; if it is a steady-state operating condition or a dynamic operating condition, proceed to the next step to perform accurate compensation calculation. Step S5: Based on the working condition flags output in step S4, adaptively call the set of compensation coefficients and calculation models that are precisely matched with the corresponding working condition from the memory storage, perform accurate calculation of static pressure and differential pressure at the differential pressure sensor (3), and finally calculate the water level after error correction.

4. The method for correcting water level errors in a steam generator as described in claim 3, characterized in that, Step S5 includes: S51. Calculate two key characteristic voltage quantities as the basis for subsequent static pressure and differential pressure calculations: ； ； in, This represents the algebraic sum of the voltages in the two output branches of the Wheatstone bridge (200); This represents the algebraic difference between the voltages of the two output branches of the Wheatstone bridge (200); S52. Based on the current operating condition flag output in step S4, the MCU processor automatically selects and calls the set of coefficients that best matches the operating condition for subsequent calculations. S53, based on Using the real-time temperature T(t) of the sensor chip obtained in step S2, the static pressure calibration model that matches the current working condition is pre-stored in the memory storage to calculate the current static pressure SP(t) acting on the differential pressure sensor (3). S54, based on Calculate the current real differential pressure value DP of the differential pressure sensor (3) based on the real-time temperature T(t) and static pressure SP(t). c (t); S55, Based on the actual differential pressure value DP c (t) Obtain the true water level h(t) of the steam generator.

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