Excitation system modeling test data speculation method and device

Abstract

The invention discloses an excitation system modeling test data speculation method and device, and relates to the field of data speculation, and the method comprises the steps: obtaining actually measured generator no-load characteristic test data; judging whether the no-load characteristic test data of the generator lacks excitation current corresponding to the percentage of the terminal voltage of the high-voltage section or not; if not, excitation system modeling is carried out based on generator no-load characteristic test data; if the excitation current does not exist, the excitation current corresponding to the percentage of the terminal voltage of the high-voltage section is speculated based on a pre-constructed nonlinear fitting function; and carrying out generator excitation system modeling on the excitation system by using generator no-load characteristic test data and the excitation current corresponding to the speculated generator terminal voltage percentage of the high-voltage section. And when the input data does not lack the high-voltage section data, the original data is directly used, so that unnecessary fitting is avoided. When the high-voltage section data is lacked, the data is speculated through the pre-constructed nonlinear fitting function, the principle is simple, and the data acquisition efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of data speculation, in particular to a method and device for modeling test data of an excitation system. BACKGROUND

[0002] When modeling an excitation system of a generator, according to the test guide (national standard, industry standard), the no-load characteristic curve needs to be measured, that is, the excitation current corresponding to 10% to 120% of the rated terminal voltage of the generator is measured. However, when the generator is running with a main transformer, in order to protect the main transformer, the terminal voltage can only be raised to 105% of the rated value, and the high-voltage section data cannot be measured, and the test guide does not provide a method for speculating the high-voltage section data in this case. Currently, technicians usually manually extend the no-load characteristic curve to obtain non-measured high-voltage section data according to experience, which is easily affected by human factors and has unstable precision. SUMMARY

[0003] The purpose of the present application is to provide a method and device for modeling test data of an excitation system, which directly uses original data when the input data does not lack high-voltage section data, avoiding unnecessary fitting. When the high-voltage section data is lacking, the data is speculated by a pre-constructed nonlinear fitting function, which is simple in principle and faster in result, improving the efficiency of data acquisition.

[0004] To solve the above technical problems, the present application provides a method for modeling test data of an excitation system, comprising:

[0005] obtaining actual measured generator no-load characteristic test data, the generator no-load characteristic test data comprising terminal voltage percentage of the generator and corresponding excitation current, the terminal voltage percentage being the percentage of the terminal voltage to the rated terminal voltage;

[0006] determining whether the generator no-load characteristic test data lacks excitation current corresponding to the terminal voltage percentage of the high-voltage section, the terminal voltage percentage of the high-voltage section being the part of the terminal voltage percentage higher than the first preset terminal voltage percentage;

[0007] if not, modeling the excitation system based on the generator no-load characteristic test data;

[0008] if yes, speculating the excitation current corresponding to the terminal voltage percentage of the high-voltage section based on a pre-constructed nonlinear fitting function;

[0009] modeling the excitation system of the generator based on the generator no-load characteristic test data and the speculated excitation current corresponding to the terminal voltage percentage of the high-voltage section.

[0010] On the other hand, the construction process of the nonlinear fitting function comprises:

[0011] Acquire historical generator no-load characteristic test data, which includes historical generator terminal voltage percentage and corresponding historical excitation current;

[0012] A line graph is plotted with the historical excitation current as the horizontal axis and the historical terminal voltage percentage as the vertical axis.

[0013] A first data point is determined in the rising segment of the original data, and a second data point is determined in the falling segment of the original data. The midpoint between the first data point and the second data point is taken. The deviation between the terminal voltage percentage corresponding to the first data point and the terminal voltage percentage corresponding to the second data point is within a preset matching range. The rising segment and the falling segment of the original data are two parts with the same number of data points except for the highest point. The horizontal and vertical coordinates of the data points in the rising segment are monotonically increasing sequentially, and the horizontal and vertical coordinates of the data points in the falling segment are monotonically decreasing sequentially.

[0014] Based on all the midpoints and the highest point of the original data, the linear part is a straight line and the nonlinear part is a curve;

[0015] Determine the nonlinear fitting function based on the nonlinear portion curve;

[0016] Adjust the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference.

[0017] The nonlinear fitting function after parameter adjustment is used as the pre-constructed nonlinear fitting function.

[0018] On the other hand, historical generator no-load characteristic test data are obtained, including:

[0019] Within the second preset terminal voltage percentage range, the historical excitation current is obtained in steps of the first percentage.

[0020] Within the third preset terminal voltage percentage range, the historical excitation current is obtained in steps of the second percentage.

[0021] Wherein, the upper limit of the second preset terminal voltage percentage range is less than the lower limit of the third preset terminal voltage percentage range, and the first percentage is greater than the second percentage.

[0022] On the other hand, after obtaining historical generator no-load characteristic test data, the following is also included:

[0023] Determine whether the historical generator no-load characteristic test data contains an original data rising segment and an original data falling segment with the same amount of data;

[0024] Determine whether the terminal voltage percentage of the historical generator no-load characteristic test data is within the preset voltage percentage range;

[0025] If the historical generator no-load characteristic test data contains an original data rising segment and an original data falling segment with the same amount of data, and the generator terminal voltage percentage is within the preset voltage percentage range, then the historical generator no-load characteristic test data is determined to be valid.

[0026] The next step is to plot a line graph using the historical excitation current as the horizontal axis and the historical terminal voltage percentage as the vertical axis.

[0027] On the other hand, based on all the midpoints and the highest points of the original data, the linear part (straight line) and the nonlinear part (curve) are obtained, including:

[0028] The curve formed by all the midpoints and the highest point of the original data is obtained, and the inflection point is determined according to the fourth preset terminal voltage percentage. The part below the fourth preset terminal voltage percentage is taken as the linear part of the straight line, and the part above the fourth preset terminal voltage percentage is taken as the nonlinear part of the curve.

[0029] On the other hand, determining the nonlinear fitting function based on the nonlinear partial curve includes:

[0030] Using x to represent the historical excitation current and y to represent the historical terminal voltage percentage, the nonlinear fitting function is determined, and the expression of the nonlinear fitting function is as follows: ;

[0031] Where a is the first undetermined parameter, b is the second undetermined parameter, and c is the third undetermined parameter;

[0032] The nonlinear fitting function is adjusted to include only the second undetermined parameter;

[0033] Adjusting the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference includes:

[0034] Determine the fitting error function with respect to the second undetermined parameter;

[0035] Adjust the value of the second undetermined parameter, and when the value of the fitting error function with respect to the second undetermined parameter is minimized, determine that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference.

[0036] On the other hand, adjusting the nonlinear fitting function to include only the second undetermined parameter includes:

[0037] The fitting curve constraint conditions for the nonlinear fitting function are determined, wherein the curve corresponding to the nonlinear fitting function needs to pass through points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. ;

[0038] According to the expression of the nonlinear fitting function The points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. Determine the correspondence between the first undetermined parameter and the second undetermined parameter, and the correspondence between the third undetermined parameter and the second undetermined parameter;

[0039] The expression for the correspondence between the first undetermined parameter and the second undetermined parameter is as follows: The expression for the correspondence between the third undetermined parameter and the second undetermined parameter is as follows: , The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point on the curve where the terminal voltage percentage is the largest, formed by the midpoint corresponding to the largest historical terminal voltage percentage and the highest point of the original data. The vertical coordinate of the point on the curve where the terminal voltage percentage is the largest, formed by the midpoint corresponding to the largest historical terminal voltage percentage and the highest point of the original data.

[0040] Based on the correspondence between the first undetermined parameter and the second undetermined parameter, and the correspondence between the third undetermined parameter and the second undetermined parameter, a nonlinear fitting function that includes only the second undetermined parameter is determined. The expression of the nonlinear fitting function that includes only the second undetermined parameter is as follows: .

[0041] On the other hand, determining the fitting error function with respect to the second undetermined parameter includes:

[0042] Determine the fitting error function between the nonlinear fitting function, which includes only the second undetermined parameter, and the historical generator no-load characteristic test data. The expression for the fitting error function is: ;

[0043] in, Let be the fitting error function for the second undetermined parameter. The terminal voltage percentage at the i-th data point on the curve formed by the midpoint and the highest point of the original data is given. The ordinate value of the i-th data point is the output of the nonlinear fitting function that includes only the second undetermined parameter. , The excitation current at the i-th data point on the curve formed by the midpoint and the highest point of the original data is given. The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point where the percentage of the terminal voltage is greatest on the curve formed by the midpoint and the highest point of the original data. The vertical coordinate of the point where the percentage of terminal voltage is the largest on the curve formed by the midpoint and the highest point of the original data.

[0044] On the other hand, adjusting the value of the second undetermined parameter, and determining that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference when the value of the fitting error function with respect to the second undetermined parameter is minimized, includes:

[0045] After a coarse scan and then a fine scan, the optimal value of the second undetermined parameter that minimizes the fitting error function is determined. ;

[0046] The coarse and fine scans are both performed by exhaustive search within a specific range to determine the value of the second parameter to be determined, and the step size of the coarse scan is larger than the step size of the fine scan.

[0047] The nonlinear fitting function after parameter adjustment is used as a pre-constructed nonlinear fitting function, including:

[0048] The optimal values ​​of the first undetermined parameter and the third undetermined parameter are determined based on the optimal value of the second undetermined parameter.

[0049] The nonlinear fitting function determined based on the optimal values ​​of the first undetermined parameter, the second undetermined parameter, and the third undetermined parameter is used as a pre-constructed nonlinear fitting function.

[0050] To address the aforementioned technical problems, the present invention also provides a device for inferring excitation system modeling test data, comprising:

[0051] Memory, used to store computer programs;

[0052] A processor is used to execute the computer program to implement the steps of the above-described method for inferring excitation system modeling test data.

[0053] This application provides a method and apparatus for inferring excitation system modeling test data, relating to the field of data inference. The method includes acquiring actual measured generator no-load characteristic test data; determining whether the generator no-load characteristic test data lacks the excitation current corresponding to the high-voltage section's terminal voltage percentage; if not lacking, modeling the excitation system based on the generator no-load characteristic test data; if lacking, inferring the excitation current corresponding to the high-voltage section's terminal voltage percentage based on a pre-constructed nonlinear fitting function; and modeling the generator excitation system using the generator no-load characteristic test data and the inferred excitation current corresponding to the high-voltage section's terminal voltage percentage. When the input data includes sufficient high-voltage section data, the original data is used directly, avoiding unnecessary fitting. When high-voltage section data is missing, inference is performed using a pre-constructed nonlinear fitting function, which is simple in principle, yields results faster, and improves data acquisition efficiency. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A flowchart of a method for inferring modeling test data of an excitation system provided by the present invention;

[0056] Figure 2 A flowchart of another method for inferring modeling test data of an excitation system provided by the present invention;

[0057] Figure 3 This invention provides a curve graph drawn based on raw data;

[0058] Figure 4 A schematic diagram of an unloaded characteristic curve and an air gap line provided for this invention;

[0059] Figure 5 A schematic diagram of the structure of a device for inferring excitation system modeling test data provided by the present invention. Detailed Implementation

[0060] The core of this invention is to provide a method and apparatus for inferring excitation system modeling test data. When high-voltage section data is available as input, the original data can be used directly, avoiding unnecessary fitting. When high-voltage section data is missing, the data is inferred using a pre-constructed nonlinear fitting function. The principle is simple, the results are obtained faster, and the efficiency of data acquisition is improved.

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] Figure 1 A flowchart of a method for inferring excitation system modeling test data provided by the present invention is included, comprising:

[0063] S11: Obtain the actual measured generator no-load characteristic test data. The generator no-load characteristic test data includes the generator terminal voltage percentage and the corresponding excitation current. The generator terminal voltage percentage is the percentage of the generator terminal voltage to the rated generator terminal voltage.

[0064] Excitation current (unit: A), generator terminal voltage percentage is the percentage of generator terminal voltage (line voltage) relative to rated generator terminal voltage (line voltage), no unit.

[0065] S12: Determine whether the generator no-load characteristic test data is missing the excitation current corresponding to the high-voltage section terminal voltage percentage. The high-voltage section terminal voltage percentage is the part of the terminal voltage percentage that is higher than the first preset terminal voltage percentage. If not, proceed to step S13; if not, proceed to step S14.

[0066] S13: Modeling the excitation system based on generator no-load characteristic test data;

[0067] Figure 2 A flowchart of another method for inferring modeling test data of an excitation system provided by the present invention;

[0068] When modeling the generator excitation system, the test guidelines (national and industry standards) require measuring the no-load characteristic curve, i.e., measuring the excitation current corresponding to 10% to 120% of the rated terminal voltage. However, when the generator is running with the main transformer, to protect the main transformer, the terminal voltage can only rise to a maximum of 105% of the rated value (i.e., the first preset terminal voltage percentage in this embodiment), making it impossible to measure the high-voltage section data. Furthermore, the test guidelines (national and industry standards) do not provide a method for inferring the high-voltage section data under these circumstances. Currently, when preparing test reports, technicians usually manually extend the no-load characteristic curve based on experience to obtain non-measured high-voltage section data, which is easily affected by human factors and has unstable accuracy.

[0069] Therefore, after obtaining the actual measured generator no-load characteristic test data, it is first necessary to determine whether it includes data from the high-voltage section. It is understandable that the fitted data will have a certain error compared with the actual data. So if the actual high-voltage section data exists, then the generator no-load characteristic test data can be used directly without obtaining it through the fitting function, thus avoiding overfitting and data distortion.

[0070] S14: Based on the pre-built nonlinear fitting function, the excitation current corresponding to the percentage of the terminal voltage in the high-voltage section is predicted;

[0071] S15: Model the generator excitation system using generator no-load characteristic test data and the excitation current corresponding to the estimated high-voltage section terminal voltage percentage.

[0072] This invention uses a pre-built nonlinear fitting function to predict the percentage of terminal voltage in high-voltage sections, avoiding the use of complex models such as neural networks and genetic algorithms that are difficult to understand and interpret. These models typically rely on specific simulation environments, such as the Matlab simulation platform, meaning users need to install specific software, and the operation and debugging process may depend on a specific programming environment, requiring additional learning and configuration work. Model tuning is also complex. For example, the training process of a neural network requires adjusting multiple parameters (such as network structure, learning rate, number of iterations, etc.), while genetic algorithms similarly require setting parameters such as population size, mutation rate, and crossover probability. These adjustments are complex and time-consuming. Inappropriate model parameter selection can lead to inaccurate training or search results, or even overfitting, underfitting, or local optima, requiring multiple debugging and verification processes, thus increasing the difficulty of use. In contrast, the nonlinear fitting function used in this invention has a clear structure, well-defined parameter meanings, and a highly interpretable calculation process, meeting accuracy requirements while significantly reducing overall complexity.

[0073] This application provides a method for inferring test data for excitation system modeling, relating to the field of data inference. The method includes acquiring actual measured generator no-load characteristic test data; determining whether the generator no-load characteristic test data lacks the percentage of the high-voltage terminal voltage; if not, modeling the generator excitation system based on the generator no-load characteristic test data; if not, inferring the excitation current corresponding to the percentage of the high-voltage terminal voltage based on a pre-constructed nonlinear fitting function; and modeling the generator excitation system using the generator no-load characteristic test data and the inferred excitation current corresponding to the percentage of the high-voltage terminal voltage. When the input data includes sufficient high-voltage data, the original data is used directly, avoiding unnecessary fitting. When high-voltage data is missing, inference is performed using a pre-constructed nonlinear fitting function, which is simple in principle, yields results faster, and improves the efficiency of data acquisition.

[0074] Based on the above embodiments:

[0075] Figure 3 This invention provides a curve graph drawn based on raw data;

[0076] Figure 4 This invention provides a schematic diagram of an unloaded characteristic curve and an air gap line. Figure 4 This includes the corresponding straight line (air gap line) drawn after completing the linear fitting, and the curves that complete the nonlinear fitting and supplement the high-pressure section data.

[0077] In some embodiments, the process of constructing the nonlinear fitting function includes:

[0078] Acquire historical generator no-load characteristic test data, which includes historical generator terminal voltage percentage and corresponding historical excitation current;

[0079] Plot a line graph with historical excitation current as the horizontal axis and historical terminal voltage percentage as the vertical axis.

[0080] The first data point is determined in the rising segment of the original data, and the second data point is determined in the falling segment of the original data. The midpoint between the first data point and the second data point is taken. The deviation between the terminal voltage percentage corresponding to the first data point and the terminal voltage percentage corresponding to the second data point is within the preset matching range. The rising segment and the falling segment of the original data are two parts with the same number of data points except for the highest point. The horizontal and vertical coordinates of the data points in the rising segment are monotonically increasing sequentially, and the horizontal and vertical coordinates of the data points in the falling segment are monotonically decreasing sequentially.

[0081] Based on all midpoints and the highest point of the original data, we obtain the linear part (straight line) and the nonlinear part (curve).

[0082] Determine the nonlinear fitting function based on the nonlinear portion of the curve;

[0083] Adjust the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than the preset difference.

[0084] The nonlinear fitting function with adjusted parameters is used as the pre-constructed nonlinear fitting function.

[0085] Using the excitation current of the example data as the x-axis and the percentage of the terminal voltage as the y-axis, a line graph is drawn as follows: Figure 3 As shown in the figure, the curve consists of two parts: the rising segment of the original data and the falling segment of the original data. The left curve represents the falling segment of the original data, and the right curve represents the rising segment of the original data.

[0086] Since there are multiple parameters in the nonlinear fitting function, the parameters need to be adjusted until the nonlinear fitting function can characterize the nonlinear part of the curve. Then, the adjusted nonlinear fitting function is used as the basis for subsequent inferences.

[0087] In some embodiments, acquiring historical generator no-load characteristic test data includes:

[0088] Within the second preset terminal voltage percentage range, the historical excitation current is obtained in steps of the first percentage.

[0089] Within the third preset terminal voltage percentage range, the historical excitation current is obtained in steps of the second percentage.

[0090] Among them, the upper limit of the second preset terminal voltage percentage range is less than the lower limit of the third preset terminal voltage percentage range, and the first percentage is greater than the second percentage.

[0091] To measure the generator terminal voltage percentage, excitation voltage, and excitation current, the software of this invention imports the excitation current and generator terminal voltage percentage. During the experiment, the excitation voltage is manually adjusted to first increase and then decrease. The excitation current and generator terminal voltage percentage will also increase and then decrease with the excitation voltage. When these values ​​change, the change in the generator terminal voltage percentage is the main focus of observation. During the rising process, measurements are taken at approximately 10%, 20%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, and 120% of the generator terminal voltage percentage. The measured generator terminal voltage percentage, excitation voltage, and excitation current data at the instant of measurement are obtained. The deviation of the measured generator terminal voltage percentage from the above values ​​should be as small as possible. During the falling process, measurements are taken at approximately 115%, 110%, 105%, 100%, 95%, 90%, 85%, 80%, 75%, 70%, 60%, 50%, 40%, 30%, 20%, and 10% of the generator terminal voltage percentage. The measured generator terminal voltage percentage, excitation voltage, and excitation current data at the instant of measurement are obtained. The deviation of the measured generator terminal voltage percentage from the above values ​​should be as small as possible. When the generator is connected to the main transformer, the highest measurable generator terminal voltage percentage is 105%. After the measurement is completed, the excitation voltage data is deleted, and the data in the form shown in Table 1 is used as the input data for the software of this invention.

[0092] Measurements were taken in increments of 10% (i.e., the first percentage in this embodiment) within the 10%–70% rated terminal voltage range (i.e., the second preset terminal voltage percentage range in this embodiment), and in increments of 5% (i.e., the second percentage in this embodiment) within the 70%–120% rated terminal voltage range (i.e., the third preset terminal voltage percentage range in this embodiment). However, during testing, it was difficult to obtain terminal voltage data that was exactly the same as the standard measurement point. The measured terminal voltage percentage values ​​were often non-integer. Therefore, the concept of terminal voltage tolerance was defined. This parameter is a manually set threshold for automatic identification of the terminal voltage. Data points with terminal voltage values ​​that are close but not necessarily identical are considered to belong to the same measurement point when the difference between the terminal voltages of two or more data points falls within this tolerance range. The value of this parameter is specified by the program user based on the actual generator no-load characteristic test data. The value should ensure that all points except the highest point can be matched pairwise. That is, the two measurement results for each measurement point are matched, with the two results for each measurement point falling on the rising and falling segments of the original no-load characteristic curve, respectively. If no matching point can be found for a point other than the highest point, or if there are two or more matching points, the program terminates and prompts the user to re-specify the tolerance value. This data verification mechanism ensures that the program accepts no-load characteristic curve data that includes both the rising and falling segments of the original data, avoiding mechanical verification of data near standard measurement points. It allows for flexible acceptance of non-standard data measured due to limitations in field conditions and rejects data with severe asymmetry between the rising and falling segments of the original data.

[0093] Of course, the values ​​of the second preset terminal voltage percentage range, the third preset terminal voltage percentage range, the first percentage and the second percentage in this embodiment are only examples. Other values ​​can be selected according to actual engineering needs. This embodiment does not make specific limitations here.

[0094] In some embodiments, after obtaining historical generator no-load characteristic test data, the method further includes:

[0095] Determine whether there are identical rising and falling segments in the historical generator no-load characteristic test data.

[0096] Determine whether the generator terminal voltage percentage in the historical generator no-load characteristic test data is within the preset voltage percentage range;

[0097] If the historical generator no-load characteristic test data contains an original data rising segment and an original data falling segment with the same amount of data, and the generator terminal voltage percentage is within the preset voltage percentage range, then the historical generator no-load characteristic test data is determined to be valid.

[0098] The next step is to plot a line graph using the historical excitation current as the horizontal axis and the historical terminal voltage percentage as the vertical axis.

[0099] Taking a set of historical generator no-load characteristic test data as an example, Table 1 is a table of historical generator no-load characteristic test data;

[0100] Table 1

[0101]

[0102] The above content is a set of valid data. The first column is the excitation current, and the second column is the percentage of the generator terminal voltage (line voltage) relative to the rated generator terminal voltage (line voltage). Looking from top to bottom, both columns of data first rise and then fall, reaching their maximum in the same row. This indicates that there are two segments of original data with the same amount of data, one rising and one falling.

[0103] In some embodiments, based on all midpoints and the highest point of the original data, a linear portion of the line and a nonlinear portion of the curve are obtained, including:

[0104] The curve is obtained by combining all midpoints and the highest point of the original data. The inflection point is determined by the fourth preset terminal voltage percentage. The part below the fourth preset terminal voltage percentage is taken as the linear part (straight line), and the part above the fourth preset terminal voltage percentage is taken as the nonlinear part (curve).

[0105] Take the midpoint of each pair of matched data points from the previous step (calculate the average value of the excitation current and terminal voltage for each pair of matched data points). The midpoint and the highest point of the original data form the midline of the no-load characteristic curve. Take the measurement point where the terminal voltage value is closest to 70% as the inflection point. Treat the part of the curve below the inflection point as the linear segment and the part of the curve above the inflection point as the nonlinear segment.

[0106] For each pair of matched data points, the midpoint is taken, specifically the midpoint between the first and second data points whose terminal voltage percentages match on the rising and falling segments of the original data. In this embodiment, the first and second data points are located on the rising and falling segments of the original data respectively and have approximately the same terminal voltage percentage. It can be understood that when the deviation between the terminal voltage percentage corresponding to the first data point and the terminal voltage percentage corresponding to the second data point is within a preset matching range, the first and second data points are considered to have approximately the same terminal voltage percentage.

[0107] For example, take the midpoints of the example data (81.691, 10.007) and (79.389, 10.005) at (80.54, 10.006), the midpoints of (173.83, 20.003) and (165.35, 20.037) at (169.59, 20.02), and so on, to obtain the midpoints of all data points matching the terminal voltage percentage. The broken line drawn based on this series of midpoints and the highest point of the example data is the broken midline. The red line is the fitted straight line obtained by performing linear regression on the linear segment of the broken midline; the equation of the fitted straight line is the linear fitting function. Let x represent the excitation current value and y represent the terminal voltage value. Using the linear fitting method, a linear fitting function is constructed for the linear segment data on the no-load characteristic curve, resulting in... The air gap line function is in the form of [formula missing], and the user can choose whether to constrain the air gap line to pass through the origin. If the air gap line is constrained to pass through the origin, the entire no-load characteristic curve is horizontally shifted to eliminate the intercept of the air gap line, making the air gap line function form [formula missing]. .

[0108] In some embodiments, determining a nonlinear fitting function based on the nonlinear portion curve includes:

[0109] Using x to represent the historical excitation current and y to represent the historical terminal voltage percentage, a nonlinear fitting function is determined. The expression for the nonlinear fitting function is as follows: ;

[0110] Where a is the first undetermined parameter, b is the second undetermined parameter, and c is the third undetermined parameter;

[0111] The nonlinear fitting function is adjusted to include only the second undetermined parameter;

[0112] Adjust the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference, including:

[0113] Determine the fitting error function with respect to the second undetermined parameter;

[0114] Adjust the value of the second undetermined parameter. When the value of the fitting error function with respect to the second undetermined parameter is minimized, determine that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than the preset difference.

[0115] Reduce the number of undetermined parameters by using constraints. This is the initial form of the nonlinear fitting function, with three undetermined parameters a, b, and c. Determining these three parameters individually is extremely complex and labor-intensive, making it difficult to implement via computer programming. By setting reasonable constraints, the other two undetermined parameters can be represented by one undetermined parameter, transforming the nonlinear fitting function into a function determined by only one undetermined parameter. This significantly simplifies the fitting method while maintaining fitting quality.

[0116] In some embodiments, adjusting the nonlinear fitting function to include only the second undetermined parameter includes:

[0117] The constraint conditions for the fitting curve of the nonlinear fitting function are determined. The constraint conditions are that the curve corresponding to the nonlinear fitting function needs to pass through the points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. ;

[0118] Based on the expression of the nonlinear fitting function The points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. Determine the correspondence between the first undetermined parameter and the second undetermined parameter, and the correspondence between the third undetermined parameter and the second undetermined parameter;

[0119] The expression for the correspondence between the first undetermined parameter and the second undetermined parameter is as follows: The expression for the correspondence between the third undetermined parameter and the second undetermined parameter is as follows: , The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point where the percentage of the terminal voltage is greatest on the curve formed by the midpoint and the highest point of the original data. The ordinate of the point where the percentage of terminal voltage is the largest on the curve formed by the midpoint and the highest point of the original data;

[0120] Based on the correspondence between the first and second undetermined parameters and the correspondence between the third and second undetermined parameters, a nonlinear fitting function including only the second undetermined parameter is determined. The expression for the nonlinear fitting function including only the second undetermined parameter is as follows: .

[0121] Let x represent the excitation current value and y represent the terminal voltage value. The constraint condition for the fitted curve is set to require it to pass through the inflection point. and the highest point According to this constraint, one undetermined parameter can be used to represent the other two undetermined parameters.

[0122] Based on the fitting curve passing through the inflection point We can obtain: ;

[0123] Based on the fitted curve passing through the highest point We can obtain: ;

[0124] Subtracting the two equations above and eliminating c, we get: ;

[0125] Simplifying, we get: ;

[0126] Therefore, we can obtain the expression for a in terms of b: ;

[0127] Will Substitution We can obtain the expression for c in terms of b: ;

[0128] Finally, the fitting function can be obtained, which is determined only by the undetermined parameter b: .

[0129] In some embodiments, determining a fitting error function with respect to a second undetermined parameter includes:

[0130] The fitting error function between the nonlinear fitting function, which includes only the second undetermined parameter, and the historical generator no-load characteristic test data is determined. The expression for the fitting error function is as follows: ;

[0131] in, Let be the fitting error function for the second undetermined parameter. Let be the percentage of the terminal voltage at the i-th data point on the curve formed by the midpoint and the highest point of the original data. The ordinate value of the i-th data point is the output of a nonlinear fitting function that includes only the second undetermined parameter. , Let be the excitation current at the i-th data point on the curve formed by the midpoint and the highest point of the original data. The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point where the percentage of the terminal voltage is greatest on the curve formed by the midpoint and the highest point of the original data. The vertical coordinate is the point where the percentage of terminal voltage is the largest on the curve formed by the midpoint and the highest point of the original data.

[0132] The asymptotes are: ;

[0133] Substituting the expressions for a and c in terms of b, we get: ;

[0134] The fitted function curve must be able to find a point where y=120, so it must satisfy: ;

[0135] in As b increases, it monotonically decreases, so b has an upper limit for scanning. : .

[0136] In some embodiments, adjusting the value of the second undetermined parameter, and determining that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference when the value of the fitting error function with respect to the second undetermined parameter is minimized, includes:

[0137] First, a coarse scan is performed, followed by a fine scan, to determine the optimal value of the second undetermined parameter that minimizes the fitting error function. ;

[0138] Both coarse and fine scanning determine the value of the second undetermined parameter within a specific numerical range using an exhaustive method. The step size of coarse scanning is larger than that of fine scanning.

[0139] The nonlinear fitting function after parameter adjustment is used as a pre-constructed nonlinear fitting function, including:

[0140] The optimal values ​​of the first and third undetermined parameters are determined based on the optimal value of the second undetermined parameter.

[0141] The nonlinear fitting function determined based on the optimal values ​​of the first, second, and third undetermined parameters is used as a pre-constructed nonlinear fitting function.

[0142] The determination was made through two-stage scanning: coarse scanning and fine scanning. The minimum optimal value of b is determined by using a larger step size to establish the initial value of b during the coarse scanning stage, and then using a smaller step size to scan only a small range around the initial value of b during the fine scanning stage to determine the optimal value of b. This can significantly reduce scanning time. For example, the scanning range of b can be set to [value missing] during the coarse scanning stage. With a step size of 0.000001, we obtain the initial value of b. During the fine scan phase, the scanning range of b is set to... With a step size of 0.00000001, the optimal value of b is obtained. The accuracy of the two scanning stages can be set according to actual needs.

[0143] Will Substituting into the nonlinear fitting function, we get: ;

[0144] in , According to The optimal values ​​of a and c are calculated.

[0145] The inverse function of the nonlinear fitting function is: .

[0146] Based on the inverse function and the y values ​​(110, 115, 120) of the standard measurement points in the high-voltage section, the corresponding x values ​​(excitation current values) can be calculated. Finally, these new data points are added to the data formed by the midpoint and the highest point of the original data.

[0147] Figure 5 This is a schematic diagram of a device for predicting excitation system modeling test data provided by the present invention. The device for predicting excitation system modeling test data includes:

[0148] Memory 21 is used to store computer programs;

[0149] The processor 22 is used to implement the steps of the above-described method for inferring excitation system modeling test data when executing a computer program.

[0150] Please refer to the above embodiments for a description of the device for inferring excitation system modeling test data provided in this application, and it will not be repeated here.

[0151] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0152] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0153] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for inferring data from modeling test data of an excitation system, characterized in that, include: Obtain the generator no-load characteristic test data obtained from actual measurements. The generator no-load characteristic test data includes the generator terminal voltage percentage and the corresponding excitation current. The generator terminal voltage percentage is the percentage of the generator terminal voltage to the rated generator terminal voltage. Determine whether the generator no-load characteristic test data is missing the excitation current corresponding to the high-voltage section terminal voltage percentage. The high-voltage section terminal voltage percentage is the portion of the terminal voltage percentage that is higher than the first preset terminal voltage percentage. If not missing, the excitation system model is performed based on the generator no-load characteristic test data; If not, the excitation current corresponding to the percentage of the generator terminal voltage of the high-voltage section is estimated based on a pre-constructed nonlinear fitting function. The generator excitation system is modeled using the generator no-load characteristic test data and the excitation current corresponding to the estimated high-voltage section terminal voltage percentage.

2. The method for inferring excitation system modeling test data as described in claim 1, characterized in that, The process of constructing the nonlinear fitting function includes: Acquire historical generator no-load characteristic test data, which includes historical generator terminal voltage percentage and corresponding historical excitation current; A line graph is plotted with the historical excitation current as the horizontal axis and the historical terminal voltage percentage as the vertical axis. A first data point is determined in the rising segment of the original data, and a second data point is determined in the falling segment of the original data. The midpoint between the first data point and the second data point is taken. The deviation between the terminal voltage percentage corresponding to the first data point and the terminal voltage percentage corresponding to the second data point is within a preset matching range. The rising segment and the falling segment of the original data are two parts with the same number of data points except for the highest point. The horizontal and vertical coordinates of the data points in the rising segment are monotonically increasing sequentially, and the horizontal and vertical coordinates of the data points in the falling segment are monotonically decreasing sequentially. Based on all the midpoints and the highest point of the original data, the linear part is a straight line and the nonlinear part is a curve; Determine the nonlinear fitting function based on the nonlinear portion curve; Adjust the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference. The nonlinear fitting function after parameter adjustment is used as the pre-constructed nonlinear fitting function.

3. The method for inferring excitation system modeling test data as described in claim 2, characterized in that, Obtain historical generator no-load characteristic test data, including: Within the second preset terminal voltage percentage range, the historical excitation current is obtained in steps of the first percentage. Within the third preset terminal voltage percentage range, the historical excitation current is obtained in steps of the second percentage. Wherein, the upper limit of the second preset terminal voltage percentage range is less than the lower limit of the third preset terminal voltage percentage range, and the first percentage is greater than the second percentage.

4. The method for inferring excitation system modeling test data as described in claim 2, characterized in that, After obtaining historical generator no-load characteristic test data, the following is also included: Determine whether the historical generator no-load characteristic test data contains an original data rising segment and an original data falling segment with the same amount of data; Determine whether the terminal voltage percentage of the historical generator no-load characteristic test data is within the preset voltage percentage range; If the historical generator no-load characteristic test data contains an original data rising segment and an original data falling segment with the same amount of data, and the generator terminal voltage percentage is within the preset voltage percentage range, then the historical generator no-load characteristic test data is determined to be valid. The next step is to plot a line graph using the historical excitation current as the horizontal axis and the historical terminal voltage percentage as the vertical axis.

5. The method for inferring excitation system modeling test data as described in claim 2, characterized in that, Based on all the midpoints and the highest point of the original data, the linear part (straight line) and the nonlinear part (curve) are obtained, including: The curve formed by all the midpoints and the highest point of the original data is obtained, and the inflection point is determined according to the fourth preset terminal voltage percentage. The part below the fourth preset terminal voltage percentage is taken as the linear part of the straight line, and the part above the fourth preset terminal voltage percentage is taken as the nonlinear part of the curve.

6. The method for inferring excitation system modeling test data as described in any one of claims 2 to 5, characterized in that, Determining the nonlinear fitting function based on the nonlinear portion curve includes: Using x to represent the historical excitation current and y to represent the historical terminal voltage percentage, the nonlinear fitting function is determined, and the expression of the nonlinear fitting function is as follows: ; Where a is the first undetermined parameter, b is the second undetermined parameter, and c is the third undetermined parameter; The nonlinear fitting function is adjusted to include only the second undetermined parameter; Adjusting the parameters of the nonlinear fitting function until the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference includes: Determine the fitting error function with respect to the second undetermined parameter; Adjust the value of the second undetermined parameter, and when the value of the fitting error function with respect to the second undetermined parameter is minimized, determine that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference.

7. The method for inferring excitation system modeling test data as described in claim 6, characterized in that, Adjusting the nonlinear fitting function to include only the second undetermined parameter includes: The fitting curve constraint conditions for the nonlinear fitting function are determined, wherein the curve corresponding to the nonlinear fitting function needs to pass through points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. ; According to the expression of the nonlinear fitting function The points on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data. The point on the curve formed by the midpoint and the highest point of the original data where the terminal voltage percentage is the largest. Determine the correspondence between the first undetermined parameter and the second undetermined parameter, and the correspondence between the third undetermined parameter and the second undetermined parameter; The expression for the correspondence between the first undetermined parameter and the second undetermined parameter is as follows: The expression for the correspondence between the third undetermined parameter and the second undetermined parameter is as follows: , The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point where the percentage of the terminal voltage is greatest on the curve formed by the midpoint and the highest point of the original data. The vertical coordinate of the point where the percentage of terminal voltage is the largest on the curve formed by the midpoint and the highest point of the original data; Based on the correspondence between the first undetermined parameter and the second undetermined parameter, and the correspondence between the third undetermined parameter and the second undetermined parameter, a nonlinear fitting function that includes only the second undetermined parameter is determined. The expression of the nonlinear fitting function that includes only the second undetermined parameter is as follows: .

8. The method for inferring excitation system modeling test data as described in claim 6, characterized in that, Determining the fitting error function with respect to the second undetermined parameter includes: Determine the fitting error function between the nonlinear fitting function, which includes only the second undetermined parameter, and the historical generator no-load characteristic test data. The expression for the fitting error function is as follows: ; in, Let be the fitting error function for the second undetermined parameter. Let be the percentage of the terminal voltage at the i-th data point on the curve formed by the midpoint and the highest point of the original data. The ordinate value of the i-th data point is the output of the nonlinear fitting function that includes only the second undetermined parameter. , The excitation current at the i-th data point on the curve formed by the midpoint and the highest point of the original data is given. The x-coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The vertical coordinate of the point on the curve formed by the midpoint corresponding to the fourth preset terminal voltage percentage and the highest point of the original data is given. The x-coordinate of the point where the percentage of the terminal voltage is greatest on the curve formed by the midpoint and the highest point of the original data. The vertical coordinate of the point where the percentage of terminal voltage is the largest on the curve formed by the midpoint and the highest point of the original data.

9. The method for inferring excitation system modeling test data as described in claim 8, characterized in that, Adjusting the value of the second undetermined parameter, and when the value of the fitting error function with respect to the second undetermined parameter is minimized, determining that the fitting error between the curve corresponding to the nonlinear fitting function and the nonlinear part curve is lower than a preset difference, includes: After a coarse scan and then a fine scan, the optimal value of the second undetermined parameter that minimizes the fitting error function is determined. ; The coarse and fine scans are both performed by exhaustive search within a specific range to determine the value of the second parameter to be determined, and the step size of the coarse scan is larger than the step size of the fine scan. The nonlinear fitting function after parameter adjustment is used as a pre-constructed nonlinear fitting function, including: The optimal values ​​of the first undetermined parameter and the third undetermined parameter are determined based on the optimal value of the second undetermined parameter. The nonlinear fitting function determined based on the optimal values ​​of the first undetermined parameter, the second undetermined parameter, and the third undetermined parameter is used as a pre-constructed nonlinear fitting function.

10. A device for predicting excitation system modeling test data, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program, implement the steps of the method for inferring excitation system modeling test data as described in any one of claims 1 to 9.

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