CN116561981A - Robust data correction method for steady-state operation process of nuclear power unit two-loop system - Google Patents

Robust data correction method for steady-state operation process of nuclear power unit two-loop system Download PDF

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CN116561981A
CN116561981A CN202310390208.8A CN202310390208A CN116561981A CN 116561981 A CN116561981 A CN 116561981A CN 202310390208 A CN202310390208 A CN 202310390208A CN 116561981 A CN116561981 A CN 116561981A
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robust
steady
data correction
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nuclear power
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申宇
朱小良
邢天阳
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Southeast University
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Abstract

The invention relates to the technical field of data correction methods, in particular to a robust data correction method for a steady-state operation process of a two-loop system of a nuclear power unit. The method comprises the steps of obtaining flow measurement variable data of a steady-state time period in a two-loop system in the running process of a nuclear power unit; based on the robust estimation function and the flow variable data, a robust steady-state data correction model is established; based on the robust steady-state data correction model, the data of each flow measurement variable is corrected, including the measured flow variable data is corrected and the unmeasured flow variable data is estimated. The data correction method can still obtain accurate correction results when significant errors exist.

Description

Robust data correction method for steady-state operation process of nuclear power unit two-loop system
Technical Field
The invention relates to the technical field of data correction methods, in particular to a robust data correction method for a steady-state operation process of a two-loop system of a nuclear power unit.
Background
The nuclear power generation is used as a clean, efficient and reliable energy source, and plays an important role in energy conservation, emission reduction, energy supply quality improvement and the like. The secondary loop system of the nuclear power unit is an indispensable component of the nuclear power unit, so that the accuracy and the reliability of data in the secondary loop system of the nuclear power unit are ensured to have important significance
The data correction technology is a method for optimally adjusting measurement data and estimating unmeasured variables on the premise of minimizing adjustment quantity by using redundant information and constraint conditions of a system. One of the preconditions for this technique is that the measurement data contains only random errors subject to normal distribution. If the measured data contains significant errors, the significant errors may be shared among other data that should not contain significant errors, thereby resulting in a deterioration of the data correction effect. The hypothesis testing method based on the statistical principle can identify significant errors, but is faced with the problems of difficult positioning and inability to correct online data.
In order to solve the problem, the invention provides a new robust estimation function based on the robust estimation theory, and further constructs a new robust data correction model to improve the reliability of data. The robustness of the robust estimation function is evaluated by the influence function, which is less affected when the significant error is larger. On the premise of steady-state operation of a two-loop system of the nuclear power unit, the redundancy and robust data correction method of the system are utilized to correct measured data, unmeasured data are estimated, and the accuracy of the data can be improved. The method has a crucial significance for operation optimization and performance monitoring of the nuclear power unit.
Disclosure of Invention
The invention aims to solve the problems in the background art, and provides a robust data correction method for a steady-state operation process of a two-loop system of a nuclear power unit, so as to solve the technical defects that the data correction result is inaccurate and is easily influenced by significant errors in the prior art.
The technical scheme of the invention is that the robust data correction method for the steady-state operation process of the two-loop system of the nuclear power unit comprises the following specific steps:
s1, acquiring flow measurement variable data of a steady-state time period in a two-loop system in the running process of a nuclear power unit;
s2, establishing a robust steady-state data correction model based on the robust estimation function and the flow variable data;
s3, based on a robust steady-state data correction model, correcting the data of each flow measurement variable, including correcting the measured flow variable data and estimating the data of the unmeasured flow variable.
The robust estimation function is:
where ρ represents the robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, σ being the standard deviation of the measured variable, a and c being both parameters of the robust function.
The influence function is:
wherein IF represents a robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, σ being the standard deviation of the measured variable, a and c being both parameters of the robust function.
The robust data correction model is:
wherein the method comprises the steps ofρ is a robust estimation function represented by equation (1), m is the number of measurement variables,represents the coordinated value, x, of the ith measured variable i Representing the measured value, sigma, of the ith measured variable i Represents standard deviation of the ith measured variable, r i Representing the relative residual of the ith measured variable, a and c are still parameters of the robust function,/>For an m-dimensional measured variable vector, U is an n-dimensional unmeasured variable vector, n is the number of unmeasured variables, feq represents an equality constraint, and f represents an inequality constraint.
The robust data correction model performs steady-state operation identification before performing data correction processing on the flow measurement variable;
the steady state operation identification comprises the following specific steps:
wherein SSC is sample standard deviation, N is time window width, t is current sample time, y i As a measurement of the condensate flow i at the moment,and θ is a threshold value, which is the average value of the flow rate of the condensate within the width of the time window.
Preferably, θ is 0.01 in the steady state operation identification determination of the power station.
Before data correction processing, constraint conditions of robust data correction are determined, and the method specifically comprises the following steps:
based on a specific heat exchanger as a unit and the law of conservation of mass, determining a linear constraint equation representing conservation of mass according to the principle that inflow is positive and outflow is negative;
inequality constraints are determined from upper and lower limit constraints of the measured variables.
And evaluating the robustness of the robust estimation function according to the influence function.
Compared with the prior art, the invention has the following beneficial technical effects:
according to the method provided by the invention, in the steady-state operation process of the nuclear power unit two-loop system, the data of each measured variable are obtained, and a robust data correction model is built based on the robust estimation function and the measured flow variable data. The data of each measured variable is then processed based on the robust data correction model, thereby reducing the effects of random errors and significant errors during operation. The robust data correction model provides accurate correction results even if significant errors exist.
Drawings
Fig. 1 is a schematic flow chart of a robust data correction method in a steady-state operation process of a two-loop system of a nuclear power unit in an embodiment of the invention.
FIG. 2 is a comparison of a robust estimation function and a weighted least squares Kong Mingfang robust estimation function in an embodiment of the present invention.
FIG. 3 is a comparison of the influence function with the weighted least squares and hole-free influence function in an embodiment of the present invention.
Fig. 4 is a schematic diagram of a robust data correction process according to an embodiment of the present invention.
FIG. 5 is a comparison of the result of robust data correction and the result of least squares data correction for the measured flow variable number 8 in an embodiment of the present invention.
FIG. 6 is a comparison of the result of robust data correction for the measured flow variable number 19 with the result of least squares data correction in an embodiment of the present invention.
FIG. 7 is a comparison of the total relative error amount of the robust data correction and the total relative error amount of the least squares data correction when significant errors are included in the embodiment of the present invention.
FIG. 8 is a graph showing uncertainty contrast before and after robust data correction for all measured variables when the measured flow variable number 8 contains significant errors in an embodiment of the present invention.
FIG. 9 is a graph showing uncertainty contrast before and after robust data correction for all measured variables when the measured flow variable No. 19 contains significant errors in an embodiment of the present invention.
Detailed Description
Example 1
The invention provides a robust data correction method for a steady-state operation process of a two-loop system of a nuclear power unit, which is shown in fig. 1, and comprises the following specific steps:
and acquiring flow measurement variable data of a steady-state time period in a two-loop system in the running process of the nuclear power unit.
The operation process of the nuclear power unit can be divided into a steady-state process and an unsteady-state process, under the condition of steady-state operation, the fluctuation amplitude of the thermal parameters of the unit is smaller, and at the moment, the sampling information can reflect the operation characteristics of the equipment under the current boundary condition in a targeted manner. The flow variable data of the unit has lower accuracy and higher uncertainty relative to the temperature and pressure variable data. Therefore, the invention designs a robust data correction method for the steady-state operation process of the two-loop system of the nuclear power unit, which is used for carrying out data correction on the flow measurement. The purpose of data correction is to correct the data of the measured variable, estimate the numerical value of the unmeasured variable and improve the data quality.
A robust data correction model is established based on a robust estimation function of the flow measurement variable data.
The robust estimation function proposed by the invention is:
where ρ represents the robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, σ being the standard deviation of the measured variable, a and c being both parameters of the robust function.
The influence function of the robust estimation function is:
wherein IF represents a robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, σ being the standard deviation of the measured variable, a and c being both parameters of the robust function.
The robust data correction model is:
wherein ρ is a robust estimation function represented by equation (1), m is the number of measurement variables,represents the coordinated value, x, of the ith measured variable i Representing the measured value, sigma, of the ith measured variable i Represents standard deviation of the ith measured variable, r i Representing the relative residual of the ith measured variable, a and c are still parameters of the robust function,/>For an m-dimensional measured variable vector, U is an n-dimensional unmeasured variable vector, n is the number of unmeasured variables, feq represents an equality constraint, and f represents an inequality constraint.
Fig. 4 is a schematic diagram of a robust data correction process according to an embodiment of the present invention.
Before the data correction processing is carried out on the flow measurement variable and the temperature measurement variable based on the robust data correction model, steady-state operation identification is needed, the operation process is ensured to be in a steady state, and the steady-state operation identification comprises the following specific steps:
wherein SSC is sample standard deviation, N is time window width, t is current sample time, y i As a measurement of the condensate flow i at the moment,and θ is a threshold value, which is the average value of the flow rate of the condensate within the width of the time window. θ may be selected to be 0.01 during steady state process decisions at the power plant.
The objective function of the robust data correction model is defined as:
f in the formula i Representing the measurement of the ith measured flow in the two-circuit system,a coordinated value, sigma, representing the i-th measured flow in a two-circuit system i The standard deviation of the i-th measured flow is shown, with a total of 19 measured flow variables.
Before data correction processing, determining constraint conditions of robust data correction, comprising the following specific steps:
based on a specific heat exchanger as a unit and the law of conservation of mass, determining a linear constraint equation representing conservation of mass according to the principle that inflow is positive and outflow is negative;
inequality constraints are determined from upper and lower limit constraints of the measured variables.
And taking a mass conservation equation of working media in a steady-state operation process of a secondary loop system of the nuclear power unit as a constraint condition for robust data correction. Mass balance equation constraints for deaerators, no. 1A high pressure heater, no. 1B high pressure heater, no. 2A high pressure heater, no. 2B high pressure heater, no. 1 pipe, and No. 2 pipe are shown in table 1.
TABLE 1
The flow variable inequality constraint is expressed as
i＝1,2,…,19,j＝1,2,3,4,
In the middle ofA correction value lower limit representing the measured flow variable; />Representing the upper limit of the correction value of the measured flow variable;representing an estimated lower limit of the unmeasured flow variable; />The upper limit of the estimated value of the unmeasured flow variable is indicated.
Fig. 2 is a graph comparing a robust estimation function with other robust estimation functions according to an embodiment of the present invention.
And correcting the measured flow variables of the deaerator, the No. 1A high-pressure heater, the No. 1B high-pressure heater, the No. 2A high-pressure heater, the No. 2B high-pressure heater, the No. 1 pipeline and the No. 2 pipeline based on the robust data correction model, and estimating the unmeasured flow variables.
And evaluating the robustness of the robust estimation function according to the influence function.
FIG. 3 is a graph of the influence function of an embodiment of the present invention.
Example 2
The invention provides a robust data correction method, which is used for carrying out data correction on flow measurement in the steady-state operation process of a two-loop system of a 50-group nuclear power unit, and superposing significant errors on specific data to judge the robustness of a robust data correction function. The weighted least squares data correction method and the robust data correction method provided by the present invention are comparatively analyzed herein.
Case 1 is that only the No. 1A high pressure heater feedwater outlet flow (i.e., no. 8 measured flow) contains significant errors, and case 2 is that only the No. 2B high pressure heater from the steam-water separator reheater flow (i.e., no. 19 measured flow) contains significant errors.
Fig. 5 and 6 show the correction results of the measured flow rates No. 8 and 19, respectively. As can be seen from fig. 5 and fig. 6, the least squares data correction method is greatly affected by significant errors and deviates farther from the true value, while the robust data correction method provided by the invention is not affected by significant errors and is closer to the true value.
Fig. 7 shows the overall relative error comparison of the robust data correction and the least squares data correction, with the overall relative error of the robust data correction being smaller and the correction result being more accurate in both cases.
In addition, fig. 8 and 9 show uncertainty contrast before and after measurement data correction using the robust data correction method provided by the present invention in case 1 and case 2. The result shows that the robust data correction model constructed by the method has high correction precision, can correct data under the condition that significant errors exist, reduces the uncertainty of the data, and has stronger robustness.
The invention provides a new robust estimation function based on a robust estimation principle, and further constructs a new robust estimation model. The method can reduce the influence of random errors and significant errors in the operation process, and even if significant errors exist, the robust data correction model can still provide accurate correction results. The above embodiments are only auxiliary cases of the present invention and are not intended to limit the present invention. The invention provides a robust data correction method for a steady-state operation process of a two-loop system of a nuclear power unit, which is capable of being modified, replaced and the like in the protection scope of the invention.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention.

Claims (8)

1. A robust data correction method for a steady-state operation process of a nuclear power unit two-loop system is characterized by comprising the following specific steps:
s1, acquiring flow measurement variable data of a steady-state time period in a two-loop system in the running process of a nuclear power unit;
s2, establishing a robust steady-state data correction model based on the robust estimation function and the flow variable data;
s3, based on a robust steady-state data correction model, correcting the data of each flow measurement variable, including correcting the measured flow variable data and estimating the data of the unmeasured flow variable.
2. The robust data correction method for steady-state operation of a two-loop system of a nuclear power unit according to claim 1, wherein the robust estimation function is:
where ρ represents the robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, sigmaThe standard deviation of the measured variables, a and c, are parameters of a robust function.
3. The robust data correction method for steady-state operation of a two-loop system of a nuclear power unit according to claim 1, wherein the influence function is:
wherein IF represents a robust estimation function,for relative residual error->Representing the correction value of the measured variable, x representing the measured value of the measured variable, σ being the standard deviation of the measured variable, a and c being both parameters of the robust function.
4. The robust data correction method for steady-state operation process of a two-loop system of a nuclear power unit according to claim 1, wherein the robust data correction model is as follows:
wherein ρ is a robust estimation function represented by equation (1), m is the number of measurement variables,represents the coordinated value, x, of the ith measured variable i Representing the measured value, sigma, of the ith measured variable i Represents standard deviation of the ith measured variable, r i Representing the relative residual of the ith measured variable, a and c are still parameters of the robust function,/>For an m-dimensional measured variable vector, U is an n-dimensional unmeasured variable vector, n is the number of unmeasured variables, feq represents an equality constraint, and f represents an inequality constraint.
5. The robust data correction method for the steady-state operation process of the two-loop system of the nuclear power unit according to claim 1, wherein steady-state operation identification is carried out before the robust data correction model carries out data correction processing on flow measurement variables;
the steady state operation identification comprises the following specific steps:
wherein SSC is sample standard deviation, N is time window width, t is current sample time, y i As a measurement of the condensate flow i at the moment,and θ is a threshold value, which is the average value of the flow rate of the condensate within the width of the time window.
6. The robust data correction method for steady-state operation of a two-loop system of a nuclear power unit according to claim 5, wherein θ is 0.01 in the steady-state operation identification judgment of the power station.
7. The robust data correction method for steady-state operation process of a two-loop system of a nuclear power unit according to claim 1, wherein the constraint condition of robust data correction is determined before data correction processing, and the specific steps are as follows:
based on a specific heat exchanger as a unit and the law of conservation of mass, determining a linear constraint equation representing conservation of mass according to the principle that inflow is positive and outflow is negative;
inequality constraints are determined from upper and lower limit constraints of the measured variables.
8. A method for correcting robust data during steady-state operation of a two-loop system of a nuclear power unit according to claim 3, wherein the robustness of the robust estimation function is evaluated according to the influence function.
CN202310390208.8A 2023-04-13 2023-04-13 Robust data correction method for steady-state operation process of nuclear power unit two-loop system Pending CN116561981A (en)

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