Reservoir scheduling calculation method based on differential form

Abstract

The invention discloses a reservoir scheduling calculation method based on a differential form. The method comprises the following steps: S1, collecting basic data and parameters; s2, establishing a water balance equation in a differential form according to engineering precision requirements; s3, according to different scheduling modes, according to the initial state of the time period, obtaining the reservoir outlet flow at the end of the time period, substituting the reservoir outlet flow into a water balance equation in a differential form to solve the reservoir capacity at the end of the time period, and querying a water level-reservoir capacity relation curve to obtain the reservoir water level at the end of the time period; and S4, taking the calculated water level of the reservoir at the end of the time period and the reservoir outlet flow as initial values of the next differential time period, and repeating the step S3 until analog calculation of the whole scheduling period is completed. According to the method, a zigzag process line is effectively avoided, continuous dynamic simulation of the reservoir water level and the reservoir-out flow is achieved through tiny time period iteration, the critical point of a control operation plan, reservoir-in flow change or gate opening adjustment can be responded in time, and the problem of water level oscillation caused by constant variables in time periods in a traditional method is avoided.

Description

Technical Field

[0001] This invention relates to the field of reservoir management, specifically to a reservoir scheduling calculation method based on differential forms. Background Technology

[0002] Reservoirs, as core water conservancy projects for regulating the spatial and temporal distribution of water resources, play an irreplaceable role in flood control and disaster reduction, water supply security, agricultural irrigation, hydropower generation, and ecological water replenishment. Reservoir scheduling is a key technical means to achieve a balance between the goals of benefiting the reservoir and eliminating its harms by scientifically regulating the reservoir's storage and release processes. The accuracy of its calculation results is directly related to the safety of the project and its socio-economic benefits.

[0003] Traditional scheduling calculations typically divide the calculation period into several time intervals, assuming that the inflow and outflow are uniform and constant within each interval, and using the finite difference method to solve the water balance equation. This discretization method is simple in principle, but it has inherent defects: because it ignores the continuous changes in hydrological and hydraulic elements within a time interval, it leads to obvious "sawtooth" oscillations and cumulative errors in the calculation results. This distortion is particularly prominent when the reservoir water level is close to the critical point of the scheduling rules, when the inflow changes drastically, or when the gate opening is adjusted, reducing the reliability and accuracy of the scheduling scheme.

[0004] Therefore, seeking a general calculation method that can overcome the defects of time-period discretization and more accurately describe the continuous scheduling process of reservoirs is of great practical engineering significance for improving the accuracy of reservoir scheduling calculations and ensuring the reliability of reservoir scheduling decisions. Summary of the Invention

[0005] One of the technical problems this application aims to solve is to overcome the shortcomings of the above-mentioned related technologies and provide a reservoir scheduling calculation method based on differential form, so as to overcome the defects of time period discretization, more accurately describe the continuous reservoir scheduling process, thereby improving the accuracy of reservoir scheduling calculation and ensuring the reliability of reservoir scheduling decisions.

[0006] The technical solution adopted by this invention to solve the technical problem is: a reservoir scheduling calculation method based on differential form, comprising the following steps: S1. Collect basic data and parameters: collect the initial water level or initial reservoir capacity at the beginning of the scheduling period, the inflow process line during the scheduling period, the water level-storage capacity relationship curve of the reservoir, the reservoir discharge capacity curve, and the scheduling rule parameters. S2. Set the calculation period length according to the engineering accuracy requirements, and establish a differential form water balance equation so that the error within the calculation period meets the accuracy requirements. S3. Based on different scheduling modes, obtain the outflow at the end of the time period according to the initial state of the time period, substitute it into the differential form of the water balance equation to solve for the reservoir capacity at the end of the time period, and query the water level-storage capacity relationship curve to obtain the reservoir water level at the end of the time period. S4. Use the reservoir water level and outflow at the end of the time period calculated in step S3 as the initial values ​​for the next differential time period, and repeat step S3 until the simulation calculation for the entire scheduling period is completed. As a preferred option, the scheduling mode for step S3 includes: Operation control plan mode: Based on the correspondence table between reservoir water level and maximum allowable outflow, a scheduling method of compensation scheduling, joint reservoir scheduling and inflow / outflow restriction is applied; Flow command mode: a scheduling method based on the correspondence table between time and outbound flow command value; Opening command mode: a scheduling method based on the correspondence table between time and gate opening command value, and the gate outflow calculation formula.

[0007] As a preferred embodiment, the differential form of the water balance equation in step S2 is as follows: ; ; In the formula, , They represent The inbound and outbound flow rates at any given time, with the outbound flow rate determined by the discharge capacity curve. and scheduling rules It was jointly determined that the discharge capacity curve and scheduling rules are related to the reservoir water level. It is represented as differential storage capacity.

[0008] Preferably, step S3 specifically includes: S31. Determine the initial state of the time period: Obtain the initial reservoir water level for the time period. Storage capacity Outbound flow and the inbound flow at the beginning and end of the period. , Outbound flow at the beginning of the scheduling period From the initial reservoir water level of the period According to the formula Calculated results; S32. Based on the selected scheduling mode, estimate the outbound flow of the scheduling rules at the end of the time period. : If it is a controlled operation plan mode: based on the reservoir water level at the beginning of the time period. For approximation, the control and operation plan table is consulted, and combined with scheduling measures such as compensation scheduling, joint reservoir scheduling, and inflow / outflow restrictions, the maximum allowable outflow corresponding to this water level is obtained as [the approximation]. The estimated value; If it is a flow command mode: This is the value of the flow command executed in the current differential time period; If it is in the opening command mode: based on the reservoir water level at the beginning of the time period. For approximation, the outflow from the weir is calculated using the given gate opening command. The estimated value; S33, based on the initial reservoir water level of the time period For approximation, the reservoir's discharge capacity curve is consulted to obtain the reservoir's discharge capacity at... instantaneous leakage capacity ; S34, according to formula Compare the estimated outbound flow at the end of the time period under each scheduling mode. With reservoir discharge capacity The minimum value is taken to obtain the outbound flow at the end of the time period. ; S35, will Substitution The reservoir storage at the end of the time period is obtained by solving the problem. ; S36. Query the water level-reservoir capacity relationship curve, from Get the reservoir water level at the end of the period .

[0009] As a preferred option, it also includes: A comparative analysis of the S5 algorithm and the reservoir flood control calculation algorithm reveals the error of this reservoir scheduling calculation method based on differential form.

[0010] Preferably, step S5 specifically includes: S51, Trial method first assumes the water level at the end of the time period = The outflow at the end of the time period is calculated based on the water level at the end of the time period. Substitution Calculate the reservoir storage at the end of the time period The reservoir water level at the end of the specified time period can be obtained by querying the water level-reservoir capacity curve. ; S52, if , To allow for error, if the accuracy requirement is met, the calculation for this period ends, and the outbound flow rate at the end of the period is calculated. Reservoir storage capacity Reservoir water level This is the calculated result; otherwise, a new assumption is made regarding the water level at the end of the time period. Return to step S51 to perform the next round of trial calculation; S53. Compare the error between the calculation results of the trial algorithm and the calculation results of the reservoir scheduling calculation method based on differential form.

[0011] Compared with related technologies, the present invention and methods have the following advantages: 1. Effectively avoids the "sawtooth" process line: Through iteration over small time periods, continuous dynamic simulation of reservoir water level and outflow is achieved, which can respond instantly to critical points of the control and operation plan, changes in inflow or gate opening, thus avoiding the water level oscillation problem caused by constant variables within a time period in traditional methods.

[0012] 2. Significantly improves the accuracy of scheduling calculations: It effectively reduces the cumulative errors caused by time period division and calculation lag, making the calculation results closer to the real physical process of the reservoir system, and providing a reliable data foundation for flood control scheduling decisions and precise utilization of water resources.

[0013] 3. The implicit water balance binary equation is converted into an explicit univariate equation for solution, avoiding the difficulties of numerical solution of implicit equations. The calculation method is simple and efficient. It can be compatible with various reservoir scheduling modes such as control and operation plan, flow command, and gate opening. It has the advantages of simplicity, convenience and high efficiency in practical engineering applications. Attached Figure Description

[0014] Figure 1 This is a flowchart of this application.

[0015] Figure 2 This is a schematic diagram comparing the water level and outflow process of the scheduling results of the method proposed in this application and the traditional scheduling method.

[0016] Figure 3 This is a diagram showing the outflow process of the reservoir under the control and operation plan model of this application.

[0017] Figure 4 This is a diagram showing the reservoir water level process under the control and operation plan model of this application.

[0018] Figure 5 This is a diagram of the reservoir outflow process under the flow command mode of this application.

[0019] Figure 6 This is a diagram of the reservoir water level process under the flow command mode of this application.

[0020] Figure 7 This is a diagram showing the outflow rate of water level under the gate opening command mode of this application.

[0021] Figure 8 This is a diagram of the water level process under the gate opening command mode of this application.

[0022] Figure 9 This is a comparison chart of outbound flow rates under the control and operation planning model of this application, using the differential method and the trial calculation method.

[0023] Figure 10This is a comparison chart of reservoir water levels using the differential method and the trial calculation method under the control and operation planning model of this application.

[0024] Figure 11 This is a scatter plot of reservoir water levels using the differential method and trial calculation method under the control and operation planning model of this application.

[0025] Figure 12 This is a diagram showing the error of the reservoir water level sequence between the differential method and the trial calculation method under the control and operation planning mode of this application. Detailed Implementation

[0026] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 The diagram shows a flowchart of a reservoir scheduling calculation method based on differential equations according to an embodiment of the present invention, including the following steps: S1. Collect basic data and parameters: Collect the initial water level at the beginning of the scheduling period. Z 0 or initial storage capacity Reservoir inflow forecast sequence (time period is...) The inflow process curve, water level-storage capacity relationship curve, reservoir discharge capacity curve, and scheduling rule parameters during the scheduling period; S2. Set the calculation period length according to the engineering accuracy requirements, and establish a differential form water balance equation so that the error within the calculation period meets the accuracy requirements. Time period The reservoir water balance equation is as follows (1): (1) In the formula, , These represent the reservoir inflow at the beginning and end of the time period, respectively. ; , These represent the reservoir outflow at the beginning and end of the time period, respectively. ; , These represent the reservoir storage at the beginning and end of the time period, in m. 3 ; The time period is long. The inflow to the reservoir at the beginning and end of the time period is known from the forecast results, while the outflow from the reservoir at the beginning of the time period is... Reservoir storage capacity It is known that the equation contains two unknowns: the reservoir outflow at the end of the time period. Reservoir storage capacity .

[0029] when hour, , , The water balance equations of the reservoir are expressed in differential form as follows (2) and (3): (2) (3) S3. Based on different scheduling modes, obtain the outflow at the end of the time period according to the initial state of the time period, substitute it into the differential form of the water balance equation to solve for the reservoir capacity at the end of the time period, and query the water level-storage capacity relationship curve to obtain the reservoir water level at the end of the time period. S4. Use the reservoir water level and outflow at the end of the time period calculated in step S3 as the initial values ​​for the next differential time period, and repeat step S3 until the simulation calculation for the entire scheduling period is completed. As a preferred option, the scheduling mode for step S3 includes: Operation control plan mode: Based on the correspondence table between reservoir water level and maximum allowable outflow, a scheduling method of compensation scheduling, joint reservoir scheduling and inflow / outflow restriction is applied; Flow command mode: a scheduling method based on the correspondence table between time and outbound flow command value; Opening command mode: a scheduling method based on the correspondence table between time and gate opening command value, and the gate outflow calculation formula.

[0030] As a preferred embodiment, the differential form of the water balance equation in step S2 is as follows: ; ; In the formula, , They represent The inbound and outbound flow rates at any given time, with the outbound flow rate determined by the discharge capacity curve. and scheduling rules It was jointly determined that the discharge capacity curve and scheduling rules are related to the reservoir water level. It is represented as differential storage capacity.

[0031] Preferably, step S3 specifically includes: S31. Determine the initial state of the time period: Obtain the initial reservoir water level for the time period. Storage capacity Outbound flow and the inbound flow at the beginning and end of the period. , Outbound flow at the beginning of the scheduling period From the initial reservoir water level of the period Calculated according to formula (3); S32. Based on the selected scheduling mode, estimate the outbound flow of the scheduling rules at the end of the time period. : If it is a controlled operation plan mode: based on the reservoir water level at the beginning of the time period. For approximation, the control and operation plan table is consulted, and combined with scheduling measures such as compensation scheduling, joint reservoir scheduling, and inflow / outflow restrictions, the maximum allowable outflow corresponding to this water level is obtained as [the approximation]. The estimated value; If it is a flow command mode: This is the value of the flow command executed in the current differential time period; If it is in the opening command mode: based on the reservoir water level at the beginning of the time period. For approximation, the outflow from the weir is calculated using the given gate opening command. The estimated value; S33, based on the initial reservoir water level of the time period For approximation, the reservoir's discharge capacity curve is consulted to obtain the reservoir's discharge capacity at... instantaneous leakage capacity ; S34. Based on equation (3), compare the estimated outbound flow at the end of the time period under each scheduling mode. With reservoir discharge capacity The minimum value is taken to obtain the outbound flow at the end of the time period. ; S35, will Substituting into equation (2), we can obtain the reservoir storage at the end of the time period. ; S36. Query the water level-reservoir capacity relationship curve, from Get the reservoir water level at the end of the period .

[0032] Figures 2-4 The figures show comparative data and process curves of the scheduling results of the traditional scheduling method and the reservoir scheduling calculation method based on differential form of this invention under three scheduling modes. The comparison shows that, compared with the traditional scheduling method, the method proposed in this invention significantly reduces the "sawtooth" oscillations of the water level process curve, lowers the error, effectively alleviates the contradiction between the discretization of the calculation period and the continuity of hydrological and hydraulic elements, and improves the reliability and accuracy of the scheduling scheme.

[0033] As a preferred option, it also includes: A comparative analysis of the S5 algorithm and the reservoir flood control calculation algorithm reveals the error of this reservoir scheduling calculation method based on differential form.

[0034] Preferably, step S5 specifically includes: S51, Trial method first assumes the water level at the end of the time period = The outflow at the end of the time period is calculated based on the water level at the end of the time period. Substituting into equation (2), the reservoir storage at the end of the time period is obtained. The reservoir water level at the end of the specified time period can be obtained by querying the water level-reservoir capacity curve. ; S52, if , To allow for error, if the accuracy requirement is met, the calculation for this period ends, and the outbound flow rate at the end of the period is calculated. Reservoir storage capacity Reservoir water level This is the calculated result; otherwise, a new assumption is made regarding the water level at the end of the time period. Return to step S51 to perform the next round of trial calculation; S53. Compare the error between the calculation results of the trial algorithm and the calculation results of the reservoir scheduling calculation method based on differential form.

[0035] The specific embodiments of the present invention are as follows: Figures 3-10 The figures show comparative data and process graphs of scheduling results for the traditional scheduling method and the scheduling method proposed in this invention under three scheduling modes. The calculation time periods for the traditional scheduling method and the differential method proposed in this invention are 1 hour and 5 minutes, respectively.

[0036] Figure 3 , Figure 4 The reservoir outflow and water level process under the controlled operation plan mode reveals that, due to the inherent limitations of this mode, the outflow abruptly changes at the critical point of the operation rule (the critical point of the reservoir water level). While the outflow remains constant within a calculation period, changes in the reservoir's storage / release status before and after the critical point inevitably lead to fluctuations in the water level between adjacent periods, resulting in a "sawtooth" oscillation in the water level process line. The longer the calculation period, the greater the oscillation amplitude. The results show that this invention, through micro-level improvements, effectively reduces the "sawtooth" oscillation of the water level process line, keeping it within the allowable error range.

[0037] Figures 5-8 For the reservoir outflow and water level process under flow command and gate opening modes, it can be seen that the outflow calculated by the traditional method cannot be adjusted in real time according to the changes in scheduling rules caused by water level changes within a time period, thus producing a large error. The outflow process line of the method proposed in this invention is significantly smoother than that of the traditional method, and it is approximately continuous within the error range, thus significantly reducing the scheduling error.

[0038] Taking the controlled operation planning model as an example, Figure 9 , Figure 10To compare the scheduling results of the differential method and the trial calculation method proposed in this invention under the controlled operation planning mode, Figure 11 , Figure 12 Scatter plots and error sequence diagrams of the reservoir water level process calculated by the two methods are shown. The calculation period for both methods is 5 minutes, and the accuracy of the trial method is within 0.01m of water level error. The results show that the results of the differential method and the trial method are similar, and the water level process and outflow process lines are basically consistent. The reservoir water level calculated by both methods basically falls on the y=x line. The calculation errors are distributed on both positive and negative sides. Statistical results show that the mean square error of the water level process for both methods is 4.6×10⁻⁶. -5 m, with an average error of 4.5*10 -3 The coefficient of determination is 0.9999, indicating that the differential method proposed in this invention has a very small error compared to the trial method, which can be ignored within the error range. Furthermore, it has a very high degree of fit with the scheduling process of the trial method, and the calculation results are highly reliable.

[0039] Compared with traditional scheduling methods, the present invention has the following advantages: 1. Effectively avoids the "sawtooth" process line: Through iteration over small time periods, continuous dynamic simulation of reservoir water level and outflow is achieved, which can respond instantly to critical points of the control and operation plan, changes in inflow or gate opening, and avoid the water level oscillation problem caused by constant variables within a time period in traditional methods.

[0040] 2. Significantly improves the accuracy of scheduling calculations: This method effectively reduces the cumulative errors caused by time period division and calculation lag, making the calculation results closer to the real physical process of the reservoir system, and providing a reliable data foundation for flood control scheduling decisions and precise utilization of water resources.

[0041] 3. The implicit water balance binary equation is converted into an explicit univariate equation for solution, avoiding the difficulties of numerical solution of implicit equations. The calculation method is simple and efficient. It can be compatible with various reservoir scheduling modes such as control and operation plan, flow command, and gate opening. It has the advantages of simplicity, convenience and high efficiency in practical engineering applications.

[0042] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for reservoir operation calculation based on differential form, characterized in that, It comprises the following steps: S1, collecting basic data and parameters: collecting the initial water level or initial reservoir capacity at the beginning of the scheduling period, the inflow process line in the scheduling period, the water level-reservoir capacity curve of the reservoir, the reservoir discharge capacity curve and the scheduling rule parameters; S2, setting the calculation period according to the engineering precision requirement, so that the error in the calculation period meets the precision requirement, and establishing the differential form of water balance equation; S3, according to different scheduling modes, the outflow at the end of the period is obtained according to the initial state of the period, which is substituted into the differential form of water balance equation to obtain the reservoir capacity at the end of the period, and the water level-reservoir capacity curve is queried to obtain the reservoir water level at the end of the period; S4, taking the reservoir water level and outflow at the end of the period calculated in step S3 as the initial value of the next differential period, repeating step S3 until the simulation calculation of the whole scheduling period is completed.

2. The differential form-based reservoir scheduling calculation method according to claim 1, wherein The scheduling mode in step S3 comprises: Control plan mode: according to the corresponding relationship table of reservoir water level and maximum allowable outflow, with compensation scheduling, joint reservoir scheduling and scheduling mode of inflow and outflow restriction; Flow instruction mode: according to the scheduling mode of the corresponding relationship table of time and outflow instruction value; Opening degree instruction mode: according to the scheduling mode of the corresponding relationship table of time and gate opening degree instruction value, and gate outflow calculation formula.

3. The method of claim 1, wherein the method is characterized by, The differential form of water balance equation in step S2 is as follows: ； ； In the formula, , They represent The inbound and outbound flow rates at any given time, with the outbound flow rate determined by the discharge capacity curve. and scheduling rules It was jointly determined that the discharge capacity curve and scheduling rules are related to the reservoir water level. It is represented as differential storage capacity.

4. The method of claim 3, wherein the method is characterized by, Step S3 specifically comprises: S31, determining the initial state of the period: obtaining the initial reservoir water level of the period , reservoir capacity , outflow , and initial and final inflow of the period , , the outflow at the beginning of the scheduling period is calculated according to the formula , obtained from the initial reservoir water level of the period ; S32, estimating the out-of-gateway traffic according to the selected scheduling mode at the end of the period : If it is the control operation plan mode: with the initial reservoir water level of the period For approximation, query the control operation plan table, and combine compensation dispatching, joint reservoir dispatching, reservoir limit, etc. Dispatching measures to obtain the maximum allowed reservoir discharge corresponding to the water level as the estimated value of ​ If flow command mode: is the flow command value executed for the current differentiation period; If the opening command mode: at the beginning of the period water level According to the given gate opening command, the estimated value of is calculated by the weir gate outflow formula. S33, initial reservoir water level of time interval For approximation, query the reservoir discharge capacity curve to obtain the discharge capacity of the reservoir at the time ; S34、According to the formula , compare the estimated outflow at the end of the period for each scheduling mode with the reservoir discharge capacity , take the minimum value to obtain the outflow at the end of the period ; S35, will Substitution The reservoir storage at the end of the time period is obtained by solving the problem. ; S36、query the water level-storage capacity relationship curve, by get the reservoir water level at the end of the period .

5. The method of claim 1 to 4, wherein, Also includes: S5 compares the error of the differential form-based reservoir scheduling calculation method with the water reservoir flood routing trial calculation method.

6. The method of claim 5, wherein the method is characterized by, Step S5 specifically comprises: S51, the trial algorithm first assumes the water level at the end of the period = , according to the water level at the end of the period to calculate the discharge at the end of the period , into the formula to obtain the reservoir storage at the end of the period , query the water level-storage curve to obtain the reservoir water level at the end of the period ; S52, if , is allowed error, the accuracy requirement is met, the period calculation is ended, and the reservoir outflow at the end of the period , reservoir storage , reservoir water level is the calculation result; otherwise, the water level at the end of the period is re-assumed , and step S51 is returned for the next round of trial calculation; S53, compare the error of the trial calculation result and the calculation result of the differential form-based reservoir scheduling calculation method.

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