A method for correcting outflow flow of hydropower station

Abstract

The present invention belongs to the technical field of reservoir dispatching, and specifically relates to a method for correcting the outflow flow of a hydropower station, including collecting and processing basic data of the hydropower station, constructing a cascade reservoir hydropower station model; constructing a water balance condition; calibrating the flow correction parameter by an optimization algorithm; correcting the NHQ characteristic curve based on the corrected parameter after calibration, and verifying the flow correction result. The present invention can solve the problem of large calculation error of the outflow flow of a power station for capacity expansion and transformation.

Description

Technical Field

[0001] The invention belongs to the technical field of reservoir dispatching, and in particular relates to a method for correcting an outflow flow of a hydropower station. Background Art

[0002] At present, with the rapid development of economy, the supply and demand of water resources have become a prominent issue affecting people's production and life, so accurate measurement of water volume is particularly important. For reservoirs, accurate calculation of outflow is of great significance to the rational management and allocation of water resources and to maintain the efficient operation of reservoirs.

[0003] For a long time, a lot of scientific research and technical research have been carried out around the scheduling of large-scale reservoir groups, and rich research results have been achieved. However, there is still a problem of water imbalance in series-connected reservoirs, and due to the long-term cumulative effects of human activities and environmental changes, various relationship curves used in calculating flow, such as unit output curves, water level and storage capacity relationship curves, and gate opening curves, cause errors in calculating reservoir water volume, and are no longer applicable to current reservoir flow calculations. Therefore, for the problem of water imbalance in series-connected reservoirs, it is urgent to propose a method for correcting the outflow flow of a hydropower station. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for correcting the outflow flow of a hydropower station.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, a method for correcting an outflow flow of a hydropower station comprises the following steps:

[0007] Step 1: Collect and process basic data of hydropower stations and build a cascade reservoir hydropower station model, including the following steps:

[0008] A1. The basic data collected include the outflow from the upper reservoir, the interval flow, the upstream water level of the lower reservoir, the downstream water level of the lower reservoir, the output of each unit of the lower reservoir power station during a certain period of time, and the discharge flow of the lower reservoir;

[0009] A2. Determine the NHQ curve of each unit of the lower reservoir power station, construct a grid surface under three-dimensional coordinates based on the NHQ curve, and determine the head loss relationship curve of the lower reservoir;

[0010] A3. Establish a cascade reservoir hydropower station model, considering two reservoir hydropower stations in series. The model includes the inflow between the two reservoirs, the flood propagation between the two reservoirs, the reservoir water level-storage capacity relationship curve, and the layout of various types of units in the reservoir;

[0011] A4. Based on the unit power generation flow calculation module of the reservoir hydropower station model, the head loss relationship curve is considered, and the upstream water level and downstream water level of the lower reservoir are used to calculate the gross head of the unit, and then the gross head and the unit output are calculated by NHQ two-dimensional interpolation to obtain the unit power generation flow. The unit power generation flow is calculated by the head loss relationship curve to obtain the unit head loss, and the accuracy is judged. If the accuracy requirement is not met, the unit power generation flow is returned to iterative calculation until the unit head loss converges to meet the accuracy requirement and the corresponding net head is obtained;

[0012] Step 2: Establish water balance conditions, including the following steps:

[0013] B1. Determine the calculation method for flood propagation between the two reservoirs;

[0014] B2. Determine the inflow confluence point between the two reservoirs;

[0015] B3. The evolution calculation method for determining the outflow of the upstream reservoir and the interval inflow to the downstream reservoir can be simplified as the outflow of the upstream reservoir and the interval flow are converted into flow observation values ​​through a certain mapping:

[0016] Q obs =f to (Q out,上 , Q 区间 );

[0017] Where Q obs is the flow observation value, that is, the flow when the upstream reservoir outflow and interval inflow evolve to the upstream inflow section of the downstream reservoir, Q out，上 is the outflow from the upstream reservoir, Q 区间 is the interval flow rate, f to Calculation of the evolution of upstream outflow and interval flow to downstream reservoirs;

[0018] Step 3: calibrate the flow correction parameters through the optimization algorithm, including the following steps:

[0019] C1. Determine the number of correction parameters that need to be calibrated;

[0020] C2. Select an optimization algorithm and construct the corresponding optimization objective function;

[0021] C3. Set the termination conditions of the optimization algorithm and perform parameter calibration;

[0022] Step 4: Correct the NHQ characteristic curve based on the calibrated correction parameters and verify the flow correction result, including the following steps:

[0023] D1. Introducing correction parameters into each NHQ characteristic curve to form a modified NHQ characteristic curve;

[0024] D2. Apply the modified NHQ characteristic curve to calculate the outbound flow rate for a series of measured data;

[0025] D3. Reverse the inflow flow based on the calculated outflow flow;

[0026] D4. Compare the inflow flow obtained by reverse calculation with the evolved flow of upstream water to verify the correction effect.

[0027] In some embodiments, the measured upstream and downstream water levels, discharge flow and unit output of the lower reservoir are imported for verifying the correction results, and the outflow flow is calculated and the inflow flow is reversed using the corrected NHQ characteristic curve to verify and evaluate the correction results. Compared with the prior art, the present invention has the following advantages:

[0028] 1. It can provide unit characteristic curves that can better meet the upstream and downstream water balance conditions in hydropower station dispatching;

[0029] 2. It can correct the errors caused by various uncertain factors in a reservoir to the greatest extent and provide effective data support for artificial experience assistance;

[0030] 3. Different flow correction coefficients can be given according to different needs to achieve accurate calculation of reservoir outflow flow.

[0031] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the present use information. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 is a method flow chart of this embodiment;

[0034] Figure 2 Schematic diagram of the calculation process of the net water head and power generation flow of the unit in this embodiment;

[0035] Figure 3 is a schematic diagram of the SCE-UA algorithm flow of this embodiment;

[0036] Figure 4 Inflow-head loss relationship curve of this embodiment;

[0037] Figure 5 Head loss curve of the unit in part B of the reservoir in this embodiment;

[0038] Figure 6 Schematic diagram of NHQ three-dimensional surface before and after correction of the units in part B of the reservoir of this embodiment;

[0039] Figure 7 Schematic diagram of the outflow curve of reservoir A-reservoir B before correction in this embodiment;

[0040] Figure 8 Schematic diagram of the corrected reservoir A-reservoir B outflow curve in this embodiment. DETAILED DESCRIPTION

[0041] The drawings are only for illustrative purposes and cannot be construed as limiting the present invention. To better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the drawings. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as limiting the present invention.

[0042] like Figure 1 As shown, a method for correcting the outflow flow of a hydropower station in this embodiment includes the following steps:

[0043] Step 1: Collect and process basic data of hydropower stations and build a cascade reservoir hydropower station model. The specific steps are as follows: Figure 2 As shown, including:

[0044] A1. Obtain the outflow flow rate of the upper reservoir, the interval flow rate, the upstream water level of the lower reservoir, the downstream water level of the lower reservoir, the output of each unit in the lower reservoir during the period, and the discharge flow rate of the lower reservoir in a certain time period;

[0045] A2. Based on the NHQ curves of each unit of the Xiaku Power Station, a grid surface under three-dimensional coordinates is formed; and the head loss relationship curve of the Xiaku Power Station is obtained;

[0046] A3. Establish a cascade reservoir hydropower station model, considering two reservoir hydropower stations in series. The model includes the inflow between the two reservoirs, the flood propagation between the two reservoirs, the reservoir water level-storage capacity relationship curve, and the layout of various types of units in the reservoir;

[0047] A4. Based on the unit power generation flow calculation module of the reservoir hydropower station model, the head loss relationship curve is considered, and the upstream water level and downstream water level of the lower reservoir are used to calculate the gross head of the unit, and then the gross head and the unit output are calculated through NHQ two-dimensional interpolation calculation to obtain the unit power generation flow. The unit power generation flow is calculated through the head loss relationship curve to obtain the unit head loss, and the accuracy is judged. If the accuracy is not met, the unit power generation flow is returned to iterative calculation until the unit head loss converges to meet the accuracy requirements and the corresponding net head is obtained.

[0048] Specifically, the iterative calculation accuracy is preferably 0.000001 or less, and the head loss relationship curve is preferably a single-machine flow-head loss relationship curve. If there is no such curve, the inflow flow-head loss relationship curve or the head loss calculation formula is used, wherein the head loss is the head that is lost due to a part of the water flow that is not utilized during the flow of water from a higher position through the water diversion building and the hydro-generator set to the downstream during the energy transmission and the conversion of water energy and electric energy. In addition, the head of the hydropower station, that is, the gross head, refers to the difference between the upstream and downstream water levels, and the calculation formula is as follows:

[0049] H sdz =Z sy -Z xy ; (1)

[0050] Among them, H sdz is the water head of the hydropower station, Z sy and Z xy are the upstream and downstream water levels of the reservoir, both in m. The head of the hydropower station minus the head loss is the net head, also known as the working head or turbine head. The unit directly uses only the net head. The calculation formula for the net head is as follows:

[0051] H T =H sdz- ΔH=Z sy -Z xy -ΔH; (2)

[0052] Among them, H T is the net head, ΔH is the total head loss in the process of energy transmission and conversion, that is, the head loss that converges to meet the accuracy requirements in A3, and the unit is m.

[0053] Step 2: Establish water balance conditions, including:

[0054] B1. Determine the calculation method for flood propagation between the two reservoirs;

[0055] B2. Determine the inflow confluence point between the two reservoirs;

[0056] B3. The evolution calculation method of the upstream reservoir outflow and interval inflow to the downstream reservoir is simplified as the upstream reservoir outflow and interval flow are converted into flow observation values ​​through a certain mapping:

[0057] Q obs =f to (Q out,上 Q 区间 ); (3)

[0058] Where Q obs is the flow observation value, that is, the flow when the upstream reservoir outflow and interval inflow evolve to the upstream inflow section of the downstream reservoir, Q out，上 is the outflow from the upstream reservoir, Q 区间 is the interval flow rate, f to Calculation of the evolution of upstream outflow and interval flow to downstream reservoirs.

[0059] Step 3: calibrate the flow correction parameters through the optimization algorithm, including the following steps:

[0060] C1. Determine the number of correction parameters that need to be calibrated;

[0061] C2. Select an appropriate optimization algorithm and construct the corresponding optimization objective function;

[0062] C3. Set the termination conditions of the optimization algorithm and perform parameter calibration.

[0063] Specifically, the optimization algorithms include SCE-UA algorithm, GA genetic algorithm, CMA-ES algorithm and PSO particle swarm optimization algorithm, and the objective function is:

[0064]

[0065] Among them, Q obs is the flow observation value, i.e., the outflow from the upper reservoir and the inflow from the interval, Q sim is the flow calculation value, that is, the inflow flow of the lower warehouse inversely calculated from the outflow flow of the lower warehouse, Q sim，i is the average reverse inflow flow of the reservoir in period i, Q obs，i is the average outflow flow and interval inflow of the upper storage during period i, is the average flow observation value, i.e. the outflow flow of the upper reservoir and the inflow of the interval, both in m 3 / s, i represents the value of the i-th time period, and T is the total time period length.

[0066] The objective function takes into account the water balance and the flow calculation value Q sim for:

[0067]

[0068] in, is the average outbound flow rate of the warehouse in period i, is the total average power generation flow of the reservoir in period i, is the average discharge flow from the reservoir during period i, Q sim，i is the average inflow flow of the reservoir in the i period, and its sequence is the flow calculation value in the objective function mentioned above. Δt is the length of the period, and f zv is the reservoir water level-storage capacity relationship fitting function, Represents the water level upstream of the lower reservoir at time i.

[0069] Specifically, the objective function is adaptively modified according to different optimization algorithms. The GA genetic algorithm uses the inverse value of the objective function as the evaluation function of the GA genetic algorithm. The CMA-ES algorithm can directly use the objective function as the fitness evaluation function. The PSO algorithm takes the inverse of the objective function as the fitness calculation formula.

[0070] Step 4: Correct the NHQ characteristic curve based on the calibrated correction parameters and verify the flow correction result, including the following steps:

[0071] D1. Introducing correction parameters into each NHQ characteristic curve to form a modified NHQ characteristic curve;

[0072] D2. Apply the modified NHQ characteristic curve to calculate the outbound flow rate for a series of measured data;

[0073] D3. Reverse the inflow flow based on the calculated outflow flow;

[0074] D4. Compare the inflow flow obtained by reverse calculation with the evolved flow of upstream water to verify the correction effect.

[0075] In some verification examples, taking the domain cascade reservoirs composed of reservoir A and reservoir B as an example, the following steps are specifically included:

[0076] Firstly, a whole month is selected as the start and end time for parameter calibration, with a time resolution of 1 hour, to obtain the outflow sequence of reservoir A, the measured water level upstream of reservoir B, the measured water level downstream of reservoir B, the output of each unit of reservoir B during the period, and the discharge flow of reservoir B.

[0077] Based on the NHQ curves of each unit in Reservoir B, a grid surface under three-dimensional coordinates is formed, and two-dimensional interpolation is applied to perform two-dimensional linear interpolation of the power generation flow under different output and head conditions; the inflow flow-head loss relationship curve of Reservoir B is obtained. Reservoir B has a total of 21 generating units, numbered 1F to 21F, of which 1F and 2F are originally rated at 170MW, and the remaining 19 are originally rated at 125MW. After the capacity expansion and transformation, the original characteristic curves of the two types of units are no longer applicable, resulting in a large deviation in the calculation of the outflow flow. The NHQ curves of the units in Reservoir B are shown in Table 1:

[0078] Table 1 NHQ curve form

[0079]

[0080]

[0081] H represents the net water head, in m; N represents the unit output, in 10,000 kilowatts; Q represents the power flow, in m 3 / s. The head loss of reservoir B is mostly caused by the pressure difference of the unit and is less affected by the flow rate of a single unit. Therefore, the head loss is calculated using the relationship curve between the inflow flow and the head loss. The curve is as follows: Figure 3 shown.

[0082] A cascade reservoir hydropower station model is established, considering two reservoir hydropower stations A and B connected in series. The model includes the inflow conditions between the two reservoirs, the flood propagation conditions between the two reservoirs, the reservoir water level-storage capacity relationship curve, and the layout of various types of units in the reservoir.

[0083] Based on the power generation flow calculation module of the hydropower station model, the head loss relationship curve is considered, and the gross head is calculated using the upstream and downstream water levels of the lower reservoir. The NHQ two-dimensional interpolation is further used for iterative calculation until the iterative calculation of the head loss converges and the corresponding net head is obtained. The head loss calculation results of the unit in part B of the reservoir are Figure 4 The calculation results of power generation and head loss are shown in Table 2:

[0084] Table 2 Calculation results of unit power flow considering head loss

[0085]

[0086]

[0087] Further, the optimization algorithm parameters are determined, taking the SCE-UA algorithm as an example, such as Figure 5As shown, the number of complexes p, the number of vertices m, and the number of sample points s involved in the evolution are determined. In addition, n, q, α, and β are included, where n represents the number of parameters, q is the number of sub-complex vertices, and the parameter s obtained by multiplying p and m describes the number of sample points, α is the number of offspring, and β is the number of offspring generations. The algorithm optimization parameter values ​​are, the algorithm optimization parameter values ​​are, m = 2n + 1, q = n + 1, s = pm, α = 1, β = m, where the number of complexes p is 2, since the number of units that need to be calibrated and corrected is 21, the total number of parameters that need to be calibrated is n = 42, thus obtaining m = 85, q = 43, s = 170, α = 1, β = 85.

[0088] In addition, the net water head calculated by NHQ two-dimensional interpolation iteration is normalized to Where h is the net water head, is the average net water head, is the standardized net water head, and the calculated average net water head is 13.181 m. S sample points are randomly generated in the feasible domain, and the function value of the sample point is calculated through the objective function, where the sample point corresponds to different correction parameters, and the function value corresponds to the value of the objective function.

[0089] The objective function is:

[0090]

[0091] Among them, Q obs is the flow observation value, that is, the flow when the upstream reservoir outflow and interval inflow evolve to the upstream inflow section of the downstream reservoir, Q sim is the flow calculation value, that is, the inflow flow of the lower warehouse inversely calculated from the outflow flow of the lower warehouse, Q sim，i is the average inflow flow in the reservoir during period i, Q obs，i is the average outflow flow and interval inflow of the upper storage during period i, is the average flow observation value, i.e. the outflow flow of the upper reservoir and the inflow of the interval, both in m 3 / s, i represents the value of the i-th time period, and T is the total time period length.

[0092] Specifically, the objective function of the SCE-UA algorithm is to calculate the flow rate Q under the condition of water balance. sim for:

[0093]

[0094] in, is the average outbound flow rate of the warehouse in period i, is the total average power generation flow of the reservoir in period i, is the average discharge flow from the reservoir during period i, Q sim，iis the average inflow flow of the reservoir in the i period, and its sequence is the flow calculation value in the objective function mentioned above. Δt is the length of the period, and f zv is the reservoir water level-storage capacity relationship fitting function, Represents the water level upstream of the lower reservoir at time i.

[0095] Furthermore, in the correction of the reservoir B, the correction of each unit depends on the linear combination of two parameters. For example, the power generation flow of the 1F unit before correction and the power generation flow after correction satisfy the following relationship:

[0096]

[0097] in is the corrected power generation flow of unit 1F at time i, is the flow rate of unit 1F before correction at time i, A 1F and B 1F is the correction parameter corresponding to the 1F unit, h i is the standardized net water head of unit 1F at time i. Thus, 21 units correspond to 42 correction parameters. In the example, the feasible domain of 21 A parameters is [0.9, 1.1], and the feasible domain of 21 B parameters is [-1, 1].

[0098] Furthermore, according to the size of the function value of the sample points, the sample points are arranged in ascending order, and then the arranged sample point group is divided into p complex types, and each complex type is evolved according to the CCE (Competitive Complex Evolution) algorithm. The new sample point set is composed of the vertices of each evolved complex type, and the new sample point set is repeatedly arranged in ascending order, and then the convergence of the result is judged. When the number of cycles is greater than or equal to 10 times and the improvement ratio of the objective function value is less than 0.01% or the change range of each parameter value in the latest 5 iterations is less than 0.01%, the operation stops, otherwise the sample points are rearranged and divided into complex types, and then evolved by the CCE algorithm. When the operation stops, the number of complex evolutions is 10 times, and the objective function value no longer changes in the double-precision operation environment and converges to the final value. Among them, the double-precision operation environment can ensure the number of effective digits of the operation result and improve the precision of the operation result.

[0099] Finally, the correction parameter calibration results are obtained to form the corrected NHQ characteristic curves of each generator set, that is, the unit characteristic curve. The three-dimensional mesh surface of the NHQ curves before and after correction of some units is shown as follows: Figure 6 The NHQ curve data of some units before and after correction are shown in Table 3:

[0100] Table 3 NHQ curve data of some units before and after correction

[0101]

[0102] Import the measured upstream and downstream water levels, discharge flow and unit output of the lower reservoir used to verify the correction results, apply the corrected NHQ characteristic curve to calculate the outflow flow and reverse the inflow flow, verify and evaluate the correction results, the outflow flow curve of reservoir A-reservoir B before correction is as follows Figure 7 As shown, the corrected outflow curve of reservoir A-reservoir B is as follows Figure 8 The flow deviation before and after correction is shown in Table 4:

[0103] Table 4 Flow deviation between reservoir A and reservoir B before and after correction

[0104]

[0105] In summary, the present invention applies a method for correcting the outflow flow of a hydropower station to the cascade reservoirs of Reservoir A-Reservoir B. Under given conditions, the model provided in this article can determine a set of power generation flow correction parameters that meet the water balance conditions based on the given measured flow, water level and output sequence. This correction process is achieved through the corrected NHQ characteristic curve, that is, a unit output characteristic curve that can better meet the upstream and downstream water balance conditions is given, so that the outflow flow calculated based on the water level and output observation data can meet the water balance conditions with the outflow flow of the upstream reservoir after the inflow flow is reversed.

[0106] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for correcting the outflow flow of a hydropower station, characterized in that: The following steps are involved: Step 1: Collect and process basic data of hydropower stations and build a cascade reservoir hydropower station model, including the following steps: A1. The basic data collected include the outflow from the upper reservoir, the interval flow, the upstream water level of the lower reservoir, the downstream water level of the lower reservoir, the output of each unit of the lower reservoir power station during a certain period of time, and the discharge flow of the lower reservoir; A2. Determine the NHQ curve of each unit of the lower reservoir power station, construct a grid surface under three-dimensional coordinates based on the NHQ curve, and determine the head loss relationship curve of the lower reservoir; A3. Establish a cascade reservoir hydropower station model, considering two reservoir hydropower stations in series. The model includes the inflow between the two reservoirs, the flood propagation between the two reservoirs, the reservoir water level-storage capacity relationship curve, and the layout of various types of units in the reservoir; A4. Based on the unit power generation flow calculation module of the reservoir hydropower station model, the head loss relationship curve is considered, and the upstream water level and downstream water level of the lower reservoir are used to calculate the gross head of the unit, and then the gross head and the unit output are calculated by NHQ two-dimensional interpolation to obtain the unit power generation flow. The unit power generation flow is calculated by the head loss relationship curve to obtain the unit head loss, and the accuracy is judged. If the accuracy requirement is not met, the unit power generation flow is returned to iterative calculation until the unit head loss converges to meet the accuracy requirement and the corresponding net head is obtained; Step 2: Establish water balance conditions, including the following steps: B1. Determine the calculation method for flood propagation between the two reservoirs; B2. Determine the inflow confluence point between the two reservoirs; B3. The evolution calculation method for determining the outflow of the upstream reservoir and the interval inflow to the downstream reservoir can be simplified as the outflow of the upstream reservoir and the interval flow are converted into flow observation values ​​through a certain mapping: Q obs =f to (Q out，上 ,Q 区间 ); Where Q obs is the flow observation value, that is, the flow when the upstream reservoir outflow and interval inflow evolve to the upstream inflow section of the downstream reservoir, Q out，上 is the outflow from the upstream reservoir, Q 区间 is the interval flow rate, f to Calculation of the evolution of upstream outflow and interval flow to downstream reservoirs; Step 3: calibrate the flow correction parameters through the optimization algorithm, including the following steps: C1. Determine the number of correction parameters that need to be calibrated; C2. Select an optimization algorithm and construct the corresponding optimization objective function; C3. Set the termination conditions of the optimization algorithm and perform parameter calibration; Step 4: Correct the NHQ characteristic curve based on the calibrated correction parameters and verify the flow correction result, including the following steps: D1. Introducing correction parameters into each NHQ characteristic curve to form a modified NHQ characteristic curve; D2. Apply the modified NHQ characteristic curve to calculate the outbound flow rate for a series of measured data; D3. Reverse the inflow flow based on the calculated outflow flow; D4. Compare the inflow flow obtained by reverse calculation with the evolved flow of upstream water to verify the correction effect.

2. A method for correcting the outflow flow of a hydropower station according to claim 1, characterized in that: The NHQ curve includes unit output, net water head and power generation flow.

3. A method for correcting the outflow flow of a hydropower station according to claim 1, characterized in that: The head loss relationship curve includes a single machine flow-head loss relationship curve, an inflow flow-head loss relationship curve and a head loss calculation formula.

4. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The iterative calculation accuracy is less than or equal to 0.000001.

5. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The head loss refers to the head that is not utilized and lost during the process of energy transmission and conversion of water energy and electrical energy when water flows from a higher position through water diversion buildings and hydro-generator sets to the downstream.

6. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The gross head is the difference between the upper and lower water levels, and the calculation formula is: H sdz =Z sy -Z xy ; Among them, H sdz is the water head of the hydropower station, Z sy and Z xy are the upstream and downstream water levels of the reservoir, both in m; The net head is the result of deducting the head loss from the gross head, and the calculation formula is: H T =H sdz -ΔH=Z sy -Z xy -Δh; Among them, H T is the net water head, ΔH is the head loss that converges to meet the accuracy, and the unit is m.

7. A method for correcting the outflow flow of a hydropower station according to claim 1, characterized in that: The flood propagation calculation method between the two reservoirs is to calculate the evolution of the upstream outflow and interval flow to the downstream reservoir.

8. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The interval inflow confluence point includes the upstream reservoir outflow and the interval flow.

9. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The optimization algorithms include SCE-UA algorithm, GA genetic algorithm, CMA-ES algorithm and PSO particle swarm optimization algorithm.

10. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The objective function is: Among them, Q obs is the flow observation value, i.e., the outflow from the upper reservoir and the inflow from the interval, Q sim is the flow calculation value, that is, the inflow flow of the lower warehouse inversely calculated from the outflow flow of the lower warehouse, Q sim，i is the average inflow flow in the reservoir during period i, Q obs，i is the average outflow flow and interval inflow of the upper storage during period i, is the average flow observation value, i.e. the outflow flow of the upper reservoir and the inflow of the interval, both in m 3 / s, i represents the value of the i-th period, and T is the total period length; The objective function takes into account the water balance and the flow calculation value Q sim for: in, is the average outbound flow rate of the warehouse in period i, is the total average power generation flow of the reservoir in period i, is the average discharge flow from the reservoir during period i, Q sim，i is the average inflow flow of the reservoir in the i period, and its sequence is the flow calculation value in the objective function mentioned above. Δt is the length of the period, and f zv is the reservoir water level-storage capacity relationship fitting function, Represents the water level upstream of the lower reservoir at time i.

11. A method for correcting outflow of a hydropower station according to claim 1, characterized in that: The measured data used to verify the correction results include: the measured upstream and downstream water levels, discharge flow and unit output of the lower reservoir. The corrected NHQ characteristic curve is used to calculate the outflow flow and reverse the inflow flow to verify and evaluate the correction results.

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