A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge

Abstract

The present invention discloses a method for diagnosing the problem of water volume imbalance in a basin hydropower station and correcting the outflow discharge, which includes the following steps: Step 1, organizing basic data; Step 2, calculating the probability distribution of the basin runoff coefficient; Step 3, for the data of unreasonable points and the data of points not falling within the confidence interval in Step 2, it is necessary to diagnose the problem according to the actual situation and judge whether there is a problem with the outflow discharge of the hydropower station corresponding to this point; Step 4, for Step 3, if there is a problem with the outflow discharge, establish the mathematical relationship between the outflow discharge of this hydropower station, the power generation discharge, and the flood discharge; calibrate the parameters α and β based on the data during the calibration period by calculating the runoff coefficient formula of this hydropower station and the downstream hydropower station; Step 5, calculate the outflow discharge of each period during the inspection period through the parameters α and β obtained during the calibration period. The present invention can handle the problem of large errors in the outflow discharge caused by water volume imbalance.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrological forecasting and reservoir operation, and more specifically, to a method for diagnosing the problem of water volume imbalance in hydropower stations in a basin and correcting the outflow discharge. Background Art

[0002] The principle of water balance is widely applied in the fields of hydrological forecasting and reservoir operation, and is one of the basic equations in hydrology. Well-known hydrological methods such as the Muskingum method are all formed based on the principle of water balance. However, in actual situations, it often occurs that the application conditions of the principle of water balance are not satisfied for the stations in the calculated basin. Especially in the basins with many water conservancy and hydropower projects, the outflow discharge is calculated based on relevant real-time data and characteristic curve data, so there are calculation errors of varying degrees, which leads to prominent problems of water volume imbalance between cascade hydropower stations (especially two extreme cases: the runoff coefficient in the interval is greater than 1.0 or is negative). Based on this situation, it is difficult for existing methods to solve this problem. The present invention proposes a method for diagnosing the problem of water volume imbalance in hydropower stations in a basin and correcting the outflow discharge to solve such problems. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a method for diagnosing the problem of water volume imbalance in hydropower stations in a basin and correcting the outflow discharge. The purpose is to seek a new calculation method to deal with the problem of large errors in the outflow discharge caused by water volume imbalance, such as two extreme cases where the runoff coefficient is greater than 1 or is negative.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a method for diagnosing the problem of water volume imbalance in hydropower stations in a basin and correcting the outflow discharge, including the following steps;

[0005] Step 1, basic data arrangement, including the following steps:

[0006] A1. Collect basic data, and the basic data includes data of the inflow discharge, power generation discharge, flood discharge, outflow discharge, and rainfall of each hydropower station;

[0007] A2. Determine the upstream and downstream relationships of each hydropower station;

[0008] A3. Divide the basic data into calibration period data and verification period data according to the calibration period and verification period respectively;

[0009] Step 2, calculate the probability distribution of the basin runoff coefficient, including the following steps:

[0010] B1. Calculate the annual runoff coefficient of each hydropower station through the basic data and formulas, and each annual runoff coefficient of a hydropower station corresponds to a point;

[0011] B2. After removing the unreasonable points, fit the remaining points into a normal or skewed curve;

[0012] B3. Select a confidence interval according to actual needs, consider the points falling within the confidence interval as reliable points, and calculate the average value of the runoff coefficients of the reliable points;

[0013] Step 3: For the data of the unreasonable points and the points not falling within the confidence interval in Step 2, diagnose their problems according to the actual situation, and determine whether there are problems with the outflow of the hydropower station corresponding to the point;

[0014] Step 4: In Step 3, if there is a problem with the outflow, establish the mathematical relationship between the outflow of the hydropower station, the power generation flow, and the flood discharge flow: Let the corrected outflow be O t =α×Q f，t +β×Q x，t , where O t is the corrected daily average outflow, Q f，t , Q x，t are the daily average power generation flow and the daily average flood discharge flow respectively; α and β are two parameters to be calibrated; calibrate the parameters α and β based on the data during the calibration period by calculating the runoff coefficient formula of the hydropower station and the downstream hydropower station;

[0015] Step 5: Calculate the outflow of each time period during the inspection period by using the parameters α and β obtained through the calibration period.

[0016] Specifically, in Step 1, the specific method of collecting basic data is to organize the basic data on a daily scale.

[0017] Specifically, in Step 1, the specific method of determining the upstream and downstream relationships of each hydropower station is as follows: Let the number of a certain hydropower station be i, and there are n hydropower stations directly connected to it upstream. The hydropower stations are located on different rivers, and their numbers are k 1 , k 2 ,..., k n , then it can be expressed as:

[0018] f(i, j)=k i ;

[0019] where f(i, j) is the number of the j-th hydropower station among the n upstream hydropower stations of the i-th hydropower station.

[0020] Specifically, in Step 2, the method of calculating the annual runoff coefficient of each hydropower station is to calculate the interval runoff depth and runoff coefficient within the calibration period of each hydropower station in the basin:

[0021]

[0022] where T1d Indicates the number of days in the calculation period; Represents the runoff depth in the interval formed by the i-th hydropower station and the upstream hydropower station during the calculation period; I i，t Represents the inflow of the i-th hydropower station at time t; O k，t Represents the outflow of the k-th hydropower station upstream of the i-th hydropower station; F i Represents the basin area corresponding to the i-th hydropower station, Represents the interval runoff coefficient of the i-th hydropower station during the calculation period, Is the rainfall within the controlled area of the hydropower station, i = 1 to m, where m represents the number of hydropower stations in the entire basin.

[0023] Particularly, in the second step, the unreasonable point data are the points with a runoff coefficient greater than 0.8 or a runoff coefficient less than 0.

[0024] Particularly, in the second step, the calculation of the mean value of the reliable point runoff coefficient is:

[0025]

[0026] Where N is the number of remaining points after excluding unreasonable points, Represents the mean value of the reliable point runoff coefficient, Represents the runoff coefficient of each point, T 1d Indicates the number of days in the calculation period.

[0027] Particularly, in the fourth step, the specific method for calibrating the parameters α and β is:

[0028] Set the objective function as:

[0029]

[0030] Where: Represents the mean value of the reliable point runoff coefficient, ψ i，y Represents the runoff coefficient of the hydropower station in the y-th year;

[0031] Particularly, the calculation formula for the runoff coefficient is:

[0032]

[0033] O k，t = α × Q kf，t + β × Q kx，t ;

[0034] Where, O k，t Represents the outflow of the hydropower station numbered k in one day, Q kf，t Represents the power generation flow of the hydropower station numbered k in one day, Q kx，tIt represents the flood discharge flow of a hydropower station numbered k within a day, where α and β are two parameters to be calibrated, namely parameter α and parameter β.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. By collecting, organizing, and calculating the basic data, the present invention calculates the runoff coefficient of the stations within the basin. Based on the probability distribution of the runoff coefficient, the possible water imbalance problems in the basin can be effectively diagnosed.

[0037] 2. By establishing the mathematical relationships among the discharge flow out of the reservoir, the power generation flow, and the flood discharge flow, and introducing the parameters α and β for calibration and verification, the present invention solves the problem of inaccurate discharge flow out of the reservoir caused by water imbalance; it can handle the problem of large errors in the discharge flow out of the reservoir caused by water imbalance, such as two extreme cases where the runoff coefficient is greater than 1 or negative.

[0038] 3. The present invention is made based on the basic principles of hydrology. By using principles such as the water balance equation to diagnose water imbalance problems and correct the discharge flow out of the reservoir, the mathematical model is simple, reliable, and easy to use. Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a flowchart of the correction method in the embodiment of the present invention;

[0041] Figure 2 It is a skewness curve graph of the runoff coefficient fitted in the embodiment of the present invention. Detailed Embodiments

[0042] The following will elaborate on the preferred embodiments of the present invention in conjunction with the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0043] It should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is customarily placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0044] In addition, terms such as "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0045] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connect", "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0046] As Figure 1 shown, a method for diagnosing the problem of water volume imbalance and correcting the outflow discharge of a basin hydropower station in this embodiment includes the following steps;

[0047] Step 1, basic data collation, including the following steps:

[0048] A1. Collect basic data, where the basic data includes the data of the inflow discharge, power generation discharge, flood discharge, outflow discharge, and rainfall of each hydropower station. The specific method for collecting basic data is to collate the basic data on a daily scale.

[0049] A2. Determine the upstream and downstream relationships of each hydropower station; the specific method is: Let the number of a certain hydropower station be i, and there are n hydropower stations directly connected to it upstream. The hydropower stations are located on different rivers, and their numbers are k 1 , k 2 ,..., k n , then it can be expressed as:

[0050] f(i, j) = k i ;

[0051] Among them, f(i, j) is the number of the j-th hydropower station among the n upstream hydropower stations of the i-th hydropower station.

[0052] A3. Divide the basic data into calibration period data and verification period data according to the calibration period and verification period respectively;

[0053] Step 2, calculate the probability distribution of the basin runoff coefficient, including the following steps:

[0054] B1. Calculate the annual runoff coefficient of each hydropower station through the basic data and the formula, and each annual runoff coefficient of the hydropower station corresponds to a point;

[0055] Calculate the interval runoff depth and runoff coefficient within the calibration period of each hydropower station in the basin:

[0056]

[0057] Among them, T 1d represents the number of days in the calculation period; represents the interval runoff depth formed by the i-th hydropower station and its upstream hydropower stations during the calculation period; I i，t represents the inflow of the i-th hydropower station at time t; O k，t represents the outflow of the k-th hydropower station upstream of the i-th hydropower station; F i represents the basin area corresponding to the i-th hydropower station, represents the interval runoff coefficient of the i-th hydropower station during the calculation period, is the rainfall within the control area of this hydropower station, i = 1 to m, where m represents the number of hydropower stations in the entire basin.

[0058] B2. After removing the unreasonable point data, fit the remaining points into a normal or skewed curve. As Figure 2 shown, it is the skewed curve of the runoff coefficient fitted in the embodiment of the present invention. The unreasonable point data are the points with a runoff coefficient greater than 0.8 or a runoff coefficient less than 0.

[0059] B3. Select the confidence interval according to actual needs, consider the points falling within the confidence interval as credible points and calculate the mean value of the credible point runoff coefficients. The calculation of the mean value of the credible point runoff coefficients is:

[0060]

[0061] Among them, N is the number of remaining points after removing the unreasonable points, represents the mean value of the credible point runoff coefficients, represents the runoff coefficient of each point, T 1d represents the number of days in the calculation period.

[0062] Step 3: For the data of the unreasonable points and the data of the points that do not fall within the confidence interval in Step 2, it is necessary to diagnose the problems according to the actual situation and judge whether there are problems with the outflow of the hydropower station corresponding to the point.

[0063] Step 4: In Step 3, if there is a problem with the outflow, establish the mathematical relationship between the outflow of the hydropower station and the power generation flow and the flood discharge flow: Let the corrected outflow be O t =α×Q f，t +β×Q x，t , where O t is the corrected daily average outflow, Q f，t , Q x，t are the daily average power generation flow and the daily average flood discharge flow respectively; α and β are two parameters to be calibrated; calibrate the parameters α and β based on the data of the calibration period by calculating the runoff coefficient formula of the hydropower station and the downstream hydropower station.

[0064] The specific method for calibrating the parameters α and β is as follows:

[0065] Set the objective function as:

[0066]

[0067] Where: represents the mean value of the runoff coefficient of the credible points, ψ i，y represents the runoff coefficient of the hydropower station in the y-th year;

[0068] Specifically, the calculation formula of the runoff coefficient is:

[0069]

[0070] O k，t =α×Q kf，t +β×Q kx，t ;

[0071] Where, O k，t represents the outflow of the hydropower station numbered k in one day, Q kf，t represents the power generation flow of the hydropower station numbered k in one day, Q kx，t represents the flood discharge flow of the hydropower station numbered k in one day, and α and β are the two parameters α and β to be calibrated.

[0072] Step 5: Calculate the outflow of each period in the inspection period through the parameters α and β obtained in the calibration period.

[0073] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, the patent owner can make various deformations or modifications within the scope of the appended claims. As long as it does not exceed the protection scope described in the claims of the present invention, it should be within the protection scope of the present invention. Specific examples are used in this article to elaborate on the principles and embodiments of the present invention. The description of the above examples is only for helping to understand the method and its core idea of the present invention. The above is only the preferred embodiment of the present invention. It should be noted that due to the limited nature of written expression and the objectively infinite specific structures, for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements, retouches or changes can be made, and the above technical features can also be combined in an appropriate manner; these improvements, retouches, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, should all be regarded as within the protection scope of the present invention.

Claims

1. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge, characterized in that: It includes the following steps: Step 1, basic data arrangement, including the following steps: A1. Collect basic data, and the basic data includes data such as the inflow discharge, power generation discharge, flood discharge, outflow discharge, and rainfall of each hydropower station; A2. Determine the upstream and downstream relationships of each hydropower station; A3. Divide the basic data into calibration period data and verification period data according to the calibration period and verification period respectively; Step 2, calculate the probability distribution of the basin runoff coefficient, including the following steps: B1. Calculate the annual runoff coefficient of each hydropower station through the basic data and formulas, and each annual runoff coefficient of a hydropower station corresponds to a point; B2. After removing the unreasonable points, fit the remaining points into a normal or skewed curve; B3. Select a confidence interval according to actual needs, and consider the points falling within the confidence interval as credible points and calculate the mean value of the credible point runoff coefficient; The unreasonable point data is the point where the runoff coefficient is greater than 0.8 or the runoff coefficient is less than 0; Step 3, for the data of the unreasonable points in Step 2 and the data of the points that do not fall within the confidence interval, it is necessary to diagnose its problem according to the actual situation and judge whether there is a problem with the outflow discharge of the hydropower station corresponding to this point; Step 4. For the situation in Step 3 where there is a problem with the outflow discharge, establish the mathematical relationship between the outflow discharge, power generation discharge, and flood discharge of this hydropower station: Let the corrected outflow discharge be O t = α × Q f ,t + β × Q x ,t, where O t is the corrected daily average outflow discharge, Q f，t , Q x，t are the daily average power generation discharge and daily average flood discharge respectively; α and β are two parameters to be calibrated; calibrate the parameters α and β based on the data during the calibration period by calculating the runoff coefficient formula of this hydropower station and the downstream hydropower station Step 5, calculate the outflow discharge of each period in the verification period through the parameters α and β obtained in the calibration period.

2. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: In the said Step 1, the specific method of collecting basic data is to arrange the basic data on a daily scale.

3. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: In the first step, the specific method for determining the upstream and downstream relationships of each hydropower station is as follows: Let the number of a certain hydropower station be i, and there are n hydropower stations directly connected to it upstream. The hydropower stations are located on different rivers, and their numbers are k 1 , k 2 ,..., k n , then it can be expressed as: f(i, j) = k i ; Among them, f(i, j) is the number of the jth hydropower station among the n upstream hydropower stations of the ith hydropower station.

4. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: In the said Step 2, the method for calculating the annual runoff coefficient of each hydropower station is to calculate the interval runoff depth and runoff coefficient within the calibration period of each hydropower station in the basin; ； Among them, T 1d represents the number of days in the calculation period; represents the runoff depth of the interval formed between the i-th hydropower station and the upstream hydropower station during the calculation period; I i，t represents the inflow of the i-th hydropower station at time t; O k，t represents the outflow of the k-th hydropower station upstream of the i-th hydropower station; F i represents the basin area corresponding to the i-th hydropower station, represents the interval runoff coefficient of the i-th hydropower station during the calculation period, is the rainfall within the control area of this hydropower station, i = 1 to m, where m represents the number of hydropower stations in the entire basin.

5. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: The calculation of the mean value of the credible point runoff coefficient is: ； Among them, N is the number of remaining points after excluding unreasonable points. represents the mean runoff coefficient of credible points. represents the runoff coefficient of each point, and T 1d represents the number of days in the calculation period.

6. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: The specific method for calibrating the parameters α and β is: Set the objective function as: ； Wherein: represents the mean value of the credible point runoff coefficient, ψ i，y represents the runoff coefficient of the hydropower station in the y-th year.

7. A method for diagnosing the water volume imbalance problem of hydropower stations in a basin and correcting the outflow discharge according to claim 1, characterized in that: The calculation formula of the runoff coefficient is: O k，t = α × Q kf，t + β × Q kx，t ; Among them, O k，t represents the outflow discharge of Hydropower Station No. k within one day, Q kf，t represents the power generation discharge of Hydropower Station No. k within one day, Q kx，t represents the flood discharge of Hydropower Station No. k within one day, and α and β are two parameters α and parameter β that need to be calibrated.

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