A cascade power station assembly type out-of-plant flow water affair calculation method

Abstract

The application discloses a kind of cascade power station assembly type discharge flow water affair calculation method, belong to the technical field of hydraulic engineering.Acquire reservoir operation data and reservoir characteristic curve, utilize the discharge flow of reservoir is calculated using three kinds of calculation modes of net water head output double linear interpolation, net water head linear interpolation and curve fitting function linear interpolation.Various problems that can appear in actual production scheduling are completely covered, multi-reservoir discharge flow parallel computing is realized, and the precision of complex scenarios is improved;Modular design realizes full-process automation, while supporting user changes in characteristic curve and other custom parameters and flexible expansion.Calculation results are output in a standardized Excel file, covering key information such as power generation flow, gate flow, and total power generation flow for each unit, significantly improving calculation efficiency and accuracy, and providing reliable technical support for fine reservoir scheduling and water resource optimization management.

Description

Technical Field

[0001] This invention belongs to the technical field of water conservancy engineering, specifically relating to a method for calculating the outflow water volume of a cascade hydropower station. Background Technology

[0002] In the joint scheduling and optimized operation of cascade hydropower stations, accurate calculation of outflow is a core element in ensuring the safe and stable operation of the power station and improving the efficiency of hydropower resource utilization. Traditional outflow calculation methods mostly rely on static characteristic curves (such as NHQ curves and gate discharge curves) and single-variable interpolation models. Their core assumption is that the operating conditions of the units and the flow rate are linearly related, and they ignore the dynamic coupling effect between head loss and power generation flow. These methods have significant drawbacks in practical applications: First, static curves do not consider the bivariate coupling characteristics of net head and gate opening, leading to the accumulation of flow calculation errors under non-integer operating conditions (such as partial load and transient processes); Second, the strong nonlinear relationship between head loss and power generation flow needs to be solved iteratively, but traditional methods lack convergence guarantee mechanisms, which can easily lead to calculation oscillations or divergences; Third, when multiple units and multiple gates are operating jointly, the discretized calculation mode is difficult to adapt to the spatiotemporal correlation requirements of cascade power stations, causing time-specific flow logic conflicts. The aforementioned problems are particularly prominent in dynamic scenarios such as frequent unit load adjustments and flood control, which severely restrict the level of refined control and economic operation capabilities of cascade power stations. Summary of the Invention

[0003] To address this technical bottleneck, this invention proposes a modular water flow calculation method for cascade hydropower stations. Through refined reconstruction of dynamic characteristic curves, multi-mode adaptive calculation strategies, and iterative convergence optimization algorithms, the method achieves high-precision calculation of outflow.

[0004] This invention employs the following technical solution: a method for calculating the outflow water volume of a cascade hydropower station, comprising the following steps:

[0005] Retrieve reservoir operation data and NHQ curves, head loss curves, and gate discharge curves from historical databases;

[0006] The NHQ curve is reconstructed by discretization based on net head and the gate discharge curve is reconstructed by opening degree, and a structured data table is established with net head and opening degree as indexes.

[0007] Using the selected generating units and gates as the calculation objects, determine the current time period. The calculation starts at the previous time period; based on the previous time period. Power generation flow Iteration to obtain the current time period Calculation of net water head ;

[0008] Based on the average output value of the unit over historical periods Select the appropriate power generation flow calculation mode, based on the calculated net water head. Get the current time period Calculation of power generation flow Set the power generation flow iteration conditions and output the calculated power generation flow that satisfies the current flow iteration conditions. That is, the current time period. Power generation flow ; to generate electricity flow The corresponding updates are made to the structured data table and then output.

[0009] During the iteration process, component-based development is carried out for each intermediate variable, and targeted optimization is performed based on time-sensitive parameters.

[0010] In a further embodiment, the process of creating the structured data table is as follows:

[0011] The upper and lower limits of the net head are read based on the NHQ curve. The net head EXCEL table is named using the upper and lower limits of the net head. The net head is used as the row index, and the power generation corresponding to different output values ​​under the same net head is stored to form a "net head-output-flow" data table.

[0012] The upper and lower limits of the gate opening are obtained using the gate discharge curve. The opening EXCEL table is named based on the upper and lower limits of the opening. The discharge flow rate corresponding to different water levels is recorded under the same net water head using the opening as the row index, forming a "opening-water level-flow rate" data table.

[0013] In a further embodiment, the current time period Calculation of net water head The iterative process is as follows:

[0014] Step 101: Based on the previous time period Power generation flow The initial head loss is calculated, and the initial net head is obtained by subtracting the initial head loss from the gross head. The initial net head is then substituted into the NHQ curve to obtain the net head. The flow rate is calculated iteratively. ;

[0015] Step 102: Obtain the net water head and calculate the flow rate iteratively. Compared with the previous period Power generation flow Iterative difference in the net water head between : ;

[0016] Step 103: Given the iterative flow error threshold for the net water head. ,like Then the output is the net water head iteratively calculated flow rate. For the current time period Calculation of net water head Conversely, proceed to step 104.

[0017] Step 104: Iteratively calculate the flow rate using the net water head. Replace the previous period Power generation flow Repeat steps 101 to 103 until... .

[0018] In a further embodiment, the current time period Power generation flow The iterative process is as follows:

[0019] Step 201: Calculate the calculated power generation flow rate using the following formula. Iteratively calculate the flow rate using the output net head. Traffic iteration traffic difference : ;

[0020] Step 202: Given a flow rate, iterate the flow rate error threshold. ,like Then the calculated power generation flow rate will be output. For the current time period Power generation flow Conversely, proceed to step 203;

[0021] Step 203: Calculate the power generation flow rate. Iterative calculation of flow rate using alternative water head Restart the current time period Calculation of net water head The iteration continues until... .

[0022] In a further embodiment, the power generation flow calculation mode includes at least: a dual linear interpolation calculation mode for net water head output, a linear interpolation calculation mode for net water head, and a linear interpolation calculation mode for NHQ curve fitting function.

[0023] In a further embodiment, the selection and adaptation process for the power generation flow calculation mode is as follows:

[0024] According to the current time period Calculation of net water head Upper limit of net head in structured data table and the lower limit of the water head ;

[0025] like Then the NHQ curve fitting function linear interpolation calculation mode is selected; if Then determine the average output value. If the value is an integer, the linear interpolation calculation mode for the net water head is selected; if it is not an integer, the dual linear interpolation calculation mode for the net water head output is selected.

[0026] In a further embodiment, the intermediate variables include at least: gross head, head loss, net head, NHQ curve, and head loss curve.

[0027] In a further embodiment, the dual linear interpolation calculation mode for the water purification head output is as follows:

[0028] Based on calculation of water head and average output value The integer difference of net water head was obtained respectively. Integer difference of output value ;

[0029] Using average output value Integer boundary values and Query curve and curve Two sets of basic traffic data were obtained; two sets of intermediate traffic values ​​were calculated based on the two sets of basic traffic data. and ;

[0030] The calculated power generation flow rate is obtained using the following formula. :

[0031] .

[0032] In a further embodiment, the linear interpolation calculation mode for the water head is as follows:

[0033] Using average output value Query curve and curve Two sets of basic traffic data were obtained, and two sets of intermediate traffic values ​​were calculated based on these two sets of basic traffic data. and Then, calculate the power generation flow. The calculation formula is as follows:

[0034] , This represents the integer difference in net water head.

[0035] In a further embodiment, the linear interpolation calculation mode of the NHQ curve fitting function is as follows:

[0036] curve and curve The first and second fitting functions are obtained by performing quadratic function fitting respectively;

[0037] The average output value The first fitted flow rate is obtained by substituting the first and second fitted functions respectively. Second fitted flow rate ;

[0038] The calculated power generation flow rate is obtained using the following formula. :

[0039] In the formula, This represents the integer difference in net water head.

[0040] The beneficial effects of this invention are as follows: The purpose of this invention is to provide a modular outflow water management model and system for cascade hydropower stations, which can efficiently and accurately solve the outflow of cascade hydropower stations under dynamic operating conditions. It is applicable to the joint scheduling and management of large hydropower stations such as the Three Gorges Reservoir and the downstream cascade reservoir group of the Jinsha River. This model overcomes the calculation bias problems of traditional methods under non-integer output, head loss coupling, and extreme operating conditions through refined reconstruction of dynamic characteristic curves, multi-mode adaptive calculation strategies, and iterative convergence optimization algorithms. It significantly improves the accuracy, stability, and calculation efficiency of outflow calculation for cascade hydropower stations, providing scientific and reliable algorithmic support for refined scheduling, economic operation, and flood control safety of power stations. Attached Figure Description

[0041] Figure 1 This is a flowchart of the water management calculation method for the component-type outflow of a cascade hydropower station in Example 1. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Example 1

[0044] like Figure 1 As shown in the figure, this embodiment discloses a method for calculating the outflow water volume of a cascade hydropower station, including the following steps:

[0045] Reservoir operation data, NHQ curves, head loss curves, and gate discharge curves are obtained from historical databases. It is worth noting that the reservoir operation data described in this embodiment includes at least reservoir operation data such as water level, flow rate, and output.

[0046] The NHQ curve is reconstructed by discretization based on net head and the gate discharge curve is reconstructed by opening degree, and a structured data table is established with net head and opening degree as indexes.

[0047] Using the selected generating units and gates as the calculation objects, determine the current time period. The calculation starts at the previous time period; based on the previous time period. Power generation flow Iteration to obtain the current time period Calculation of net water head ;

[0048] Based on the average output value of the unit over historical periods Select the appropriate power generation flow calculation mode, based on the calculated net water head. Get the current time period Calculation of power generation flow Set the power generation flow iteration conditions and output the calculated power generation flow that satisfies the current flow iteration conditions. That is, the current time period. Power generation flow ; to generate electricity flow The corresponding updates are made to the structured data table and then output.

[0049] During the iteration process, each intermediate variable is developed in a component-based manner and optimized specifically based on time-sensitive parameters. These intermediate variables include at least: gross head, head loss, net head, NHQ curve, and head loss curve. In other words, the component-based development and time-series optimization of intermediate variables, through "modular encapsulation and dynamic parameter adjustment," achieves flexibility and adaptability in the computational model, meeting the accuracy requirements of daily scheduling of cascade hydropower stations while providing an expansion interface for future intelligent upgrades.

[0050] In a further embodiment, the process of creating a structured data table is as follows:

[0051] The upper and lower limits of the net head are read based on the NHQ curve. The net head EXCEL table is named using the upper and lower limits of the net head. The net head is used as the row index, and the power generation corresponding to different output values ​​under the same net head is stored to form a "net head-output-flow" data table.

[0052] The upper and lower limits of the gate opening are obtained using the gate discharge curve. The opening EXCEL table is named based on the upper and lower limits of the opening. The discharge flow rate corresponding to different water levels is recorded under the same net water head using the opening as the row index, forming a "opening-water level-flow rate" data table.

[0053] Taking the NHQ curves of all types of generator units at the Three Gorges Dam as an example, a structured Excel data table indexed by net head is used to achieve rapid querying and matching of characteristic curves. The Excel tables are named as follows: Three Gorges Right Bank East Generator Unit Flow Curve, Three Gorges Underground Power Station ALSTOM Unit Flow Curve, and Three Gorges VGS Unit Flow Curve. Correspondingly, in this embodiment, the current time period is set. The calculation starts at 00:00 on January 1, 2023, and the current time period is... It takes 4320 hours.

[0054] Based on the above description, the current time period Calculation of net water head The iterative process is as follows:

[0055] Step 101: Based on the previous time period Power generation flow The initial head loss is calculated, and the initial net head is obtained by subtracting the initial head loss from the gross head. The initial net head is then substituted into the NHQ curve to obtain the net head. The flow rate is calculated iteratively. ;

[0056] Step 102: Obtain the net water head and calculate the flow rate iteratively. Compared with the previous period Power generation flow Iterative difference in the net water head between : ;

[0057] Step 103: Given the iterative flow error threshold for the net water head. ,like Then the output is the net water head iteratively calculated flow rate. For the current time period Calculation of net water head Conversely, proceed to step 104.

[0058] Step 104: Iteratively calculate the flow rate using the net water head. Replace the previous period Power generation flow Repeat steps 101 to 103 until... .

[0059] Furthermore, the power generation flow calculation modes include at least: a dual linear interpolation calculation mode for net head output, a linear interpolation calculation mode for net head, and a linear interpolation calculation mode for NHQ curve fitting function. Therefore, the selection and adaptation process for the power generation flow calculation mode is as follows:

[0060] According to the current time period Calculation of net water head Upper limit of net head in structured data table and the lower limit of the water head ;

[0061] like Then the NHQ curve fitting function linear interpolation calculation mode is selected; if Then determine the average output value. If the value is an integer, the linear interpolation calculation mode for the net water head is selected; if it is not an integer, the dual linear interpolation calculation mode for the net water head output is selected.

[0062] After determining the corresponding power generation flow calculation mode, the current time period Power generation flow The iterative process is as follows:

[0063] Step 201: Calculate the calculated power generation flow rate using the following formula. Iteratively calculate the flow rate using the output net head. Traffic iteration traffic difference : ;

[0064] Step 202: Given a flow rate, iterate the flow rate error threshold. ,like Then the calculated power generation flow rate will be output. For the current time period Power generation flow Conversely, proceed to step 203;

[0065] Step 203: Calculate the power generation flow rate. Iterative calculation of flow rate using alternative water head Restart the current time period Calculation of net water head The iteration continues until... .

[0066] Based on the above description, this embodiment ensures that the dynamic coupling relationship between the parameters "head loss - net head - power generation flow" is accurately solved through dual closed-loop calculations of power generation head iteration (steps 101-104) and power generation flow iteration (steps 201-203), and the error can be controlled within a preset threshold (e.g., , To avoid the cumulative errors of traditional methods, and referring to Table 1, the power generation flow of the Three Gorges Unit 1 at 10:00 AM on January 7, 2023, was calculated through four iterations, with a final result of 422.07 m³ / s; the power generation flow at 12:00 PM was calculated through five iterations, with a final result of 761.29 m³ / s; and the power generation flow at 2:00 PM was calculated through four iterations, with a final result of 782.12 m³ / s.

[0067] Table 1. Iterative data table for calculating the Three Gorges Dam Unit 1

[0068]

[0069] For different output and head scenarios (non-integer, integer, and out-of-range), a dual linear interpolation calculation mode for head output, a linear interpolation calculation mode for head, and a linear interpolation calculation mode for NHQ curve fitting function are adopted respectively to avoid calculation deviation of static curve under non-integer operating conditions.

[0070] Furthermore, the dual linear interpolation calculation mode for the water purification head output is as follows:

[0071] Based on calculation of water head and average output value The integer difference of net water head was obtained respectively. Integer difference of output value In a further embodiment, the integer difference in net water head... Integer difference between output value and output value The calculation formula is as follows: , , This indicates rounding down to the nearest integer.

[0072] Using average output value Integer boundary values and Query curve and curve Two sets of basic traffic data were obtained; two sets of intermediate traffic values ​​were calculated based on the two sets of basic traffic data. and The calculated power generation flow rate is obtained using the following formula. : .

[0073] For ease of understanding, among them, , , representing the average output value The positive lower and upper boundaries, such as hour, Correspondingly, Correspondingly, the curve The table shows the flow characteristics of the unit at a lower net water head, and the curves are... To represent the unit's flow characteristics at higher net head conditions, the two sets of curves represent the relationship between unit output (N) and power generation flow (Q) under adjacent net head conditions. Therefore, the two sets of basic flow data are based on the curves... The output obtained from the query is Power generation flow value , output as Power generation flow value and the base curve The output obtained from the query is Power generation flow value , output as Power generation flow value .

[0074] Therefore, the two sets of intermediate flow values and The calculation formula is as follows:

[0075] ;

[0076] .

[0077] Correspondingly, when the average output value When the value is an integer, the linear interpolation calculation mode for the net head is as follows: using the average output value Query curve and curve Two sets of intermediate flow values ​​were obtained directly. and Then, calculate the power generation flow. The calculation formula is as follows:

[0078] , This is the integer difference in net head, and its calculation method has been explained above and will not be repeated here.

[0079] Finally, the linear interpolation calculation mode for the NHQ curve fitting function is as follows:

[0080] curve and curve The first and second fitting functions are obtained by performing quadratic function fitting respectively; the mathematical forms of the first and second fitting functions are as follows:

[0081] .

[0082] Determining coefficients using the method of minimizing the squared error and the least squares method The value of , where, For input variables, This is the output value.

[0083] The average output value The first fitted flow rate is obtained by substituting the first and second fitted functions respectively. Second fitted flow rate ;

[0084] The calculated power generation flow rate is obtained using the following formula. :

[0085] In the formula, This represents the integer difference in net water head.

[0086] Based on the above calculations and iterations, the power generation flow rate The data is updated to the corresponding unit number in the structured data table and output as an Excel file, as shown in Table 2.

[0087] Table 2 Excel spreadsheet file

[0088]

[0089] Example 2

[0090] This embodiment discloses a modular outflow water management calculation system for cascade hydropower stations, used in the modular outflow water management calculation method for cascade hydropower stations described in Embodiment 1, including:

[0091] The first module is set to retrieve reservoir operation data and NHQ curves, head loss curves, and gate discharge curves from the historical database.

[0092] The second module is set to perform bivariate discretization and reconstruction of the NHQ curve according to the net head and the gate discharge curve according to the opening degree, and establish a structured data table indexed by the net head and the opening degree.

[0093] The third module is configured to use selected generator units and gates as the calculation objects to determine the current time period. The calculation starts at the previous time period; based on the previous time period. Power generation flow Iteration to obtain the current time period Calculation of net water head ;

[0094] The fourth module is set to be based on the unit's average output value over historical periods. Select the appropriate power generation flow calculation mode, based on the calculated net water head. Get the current time period Calculation of power generation flow Set the power generation flow iteration conditions and output the calculated power generation flow that satisfies the current flow iteration conditions. That is, the current time period. Power generation flow ; to generate electricity flow The corresponding updates are made to the structured data table and then output.

[0095] The fifth module is designed to be developed in a component-based manner for each intermediate variable during the iteration process, and to be optimized in a targeted manner based on time-sensitive parameters.

Claims

1. A method for calculating the outflow water volume of a cascade hydropower station, characterized in that, Includes the following steps: Retrieve reservoir operation data and NHQ curves, head loss curves, and gate discharge curves from historical databases; The NHQ curve is reconstructed by discretization based on net head and the gate discharge curve is reconstructed by opening degree, and a structured data table is established with net head and opening degree as indexes. Using the selected generating units and gates as the calculation objects, determine the current time period. The calculation starts at the previous time period; based on the previous time period. Power generation flow Iteration to obtain the current time period Calculation of net water head ; Based on the average output value of the unit over historical periods Select the appropriate power generation flow calculation mode, based on the calculated net water head. Get the current time period Calculation of power generation flow ; The power generation flow calculation mode includes at least: a dual linear interpolation calculation mode for net water head output, a linear interpolation calculation mode for net water head, and a linear interpolation calculation mode for NHQ curve fitting function; Set the generation flow iteration conditions and output the calculated generation flow that satisfies the current iteration conditions. That is, the current time period. Power generation flow ; to generate electricity flow The corresponding updates are made to the structured data table and then output. During the iteration process, component-based development is carried out for each intermediate variable, and targeted optimization is performed based on time-sensitive parameters; the current time period Calculation of net water head The iterative process is as follows: Step 101: Based on the previous time period Power generation flow The initial head loss is calculated, and the initial net head is obtained by subtracting the initial head loss from the gross head. The initial net head is then substituted into the NHQ curve to obtain the net head. The flow rate is calculated iteratively. ; Step 102: Obtain the net water head and calculate the flow rate iteratively. Compared with the previous period Power generation flow Iterative difference in the net water head between : ; Step 103: Given the iterative flow error threshold for the net water head. ,like Then the output is the net water head iteratively calculated flow rate. For the current time period Calculation of net water head Conversely, proceed to step 104. Step 104: Iteratively calculate the flow rate using the net water head. Replace the previous period Power generation flow Repeat steps 101 to 103 until... ; The current time period Power generation flow The iterative process is as follows: Step 201: Calculate the calculated power generation flow rate using the following formula. Iteratively calculate the flow rate using the output net head. Traffic iteration traffic difference : ; Step 202: Given a flow rate, iterate the flow rate error threshold. ,like Then the calculated power generation flow rate will be output. For the current time period Power generation flow Conversely, proceed to step 203; Step 203: Calculate the power generation flow rate. Iterative calculation of flow rate using alternative water head Restart the current time period Calculation of net water head The iteration continues until... .

2. The method for calculating the outflow water volume of a cascade hydropower station module according to claim 1, characterized in that, The process of creating the structured data table is as follows: The upper and lower limits of the net head are read based on the NHQ curve, and the net head EXCEL table is named using the upper and lower limits of the net head. The net head is used as the row index, and the power generation corresponding to different output values ​​under the same net head is stored to form a "net head-output-flow" data table. The upper and lower limits of the gate opening are obtained using the gate discharge curve, and the opening EXCEL table is named based on the upper and lower limits of the opening. Using the opening degree as the row index, the discharge flow rate corresponding to different water levels under the same net water head is recorded to form a "opening degree-water level-flow rate" data table.

3. The method for calculating the outflow of water from a cascade hydropower station as described in claim 1, characterized in that, The selection and adaptation process for the power generation flow calculation mode is as follows: According to the current time period Calculation of net water head Upper limit of net head in structured data table and the lower limit of the water head ; like Then the NHQ curve fitting function linear interpolation calculation mode is selected; if Then determine the average output value. If the value is an integer, the linear interpolation calculation mode for the net water head is selected; if it is not an integer, the dual linear interpolation calculation mode for the net water head output is selected.

4. The method for calculating the outflow water volume of a cascade hydropower station module according to claim 1, characterized in that, The intermediate variables include at least: gross head, head loss, net head, NHQ curve, and head loss curve.

5. The method for calculating the outflow water volume of a cascade hydropower station module according to claim 1, characterized in that, The dual linear interpolation calculation mode for the water purification head output is as follows: Based on calculation of water head and average output value The integer difference of net water head was obtained respectively. Integer difference of output value ; Using average output value Integer boundary values and Query curve and curve Two sets of basic traffic data were obtained; two sets of intermediate traffic values ​​were calculated based on the two sets of basic traffic data. and ; The calculated power generation flow rate is obtained using the following formula. : 。 6. The method for calculating the outflow of water from a cascade hydropower station as described in claim 1, characterized in that, The linear interpolation calculation mode for the water head is as follows: Using average output value Query curve and curve Two sets of basic traffic data were obtained, and two sets of intermediate traffic values ​​were calculated based on these two sets of basic traffic data. and Then, calculate the power generation flow. The calculation formula is as follows: , This represents the integer difference in net water head.

7. The method for calculating the outflow of water from a cascade hydropower station as described in claim 1, characterized in that, The linear interpolation calculation mode of the NHQ curve fitting function is as follows: curve and curve The first and second fitting functions are obtained by performing quadratic function fitting respectively; The average output value The first fitted flow rate is obtained by substituting the first and second fitted functions respectively. Second fitted flow rate ; The calculated power generation flow rate is obtained using the following formula. : In the formula, This represents the integer difference in net water head.

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