Method for defining sediment in series of upper and lower reservoirs of hybrid pumped storage power station and sediment passing through machine

Abstract

The application discloses a method for defining the scouring and silting series connection and machine-passing sediment of upper and lower reservoirs of a hybrid pumped storage power station, which comprises the following steps: obtaining data, including the daily scheduling process of the hybrid pumped storage power station and each time period, simultaneously performing the sediment scouring and silting calculation of the upper and lower reservoirs, including the flow calculation and the sediment calculation, simulating the exchange of the upper and lower reservoirs with water pumping and water releasing, and outputting the siltation form and distribution of the upper and lower reservoirs, the machine-passing sediment concentration and gradation, the siltation amount and sediment discharge ratio of the upper and lower reservoirs, and the siltation distribution of the inlet and outlet cross sections. According to the method, the sediment siltation of the upper and lower reservoirs which are both river type reservoirs, the scouring and silting conditions near the water inlet and outlet, and the machine-passing sediment concentration and gradation can be simulated according to the operation conditions and water and sediment characteristics of the hybrid pumped storage power station.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering technology, specifically to a method for the siltation and sedimentation linkage of upper and lower reservoirs in a hybrid pumped storage power station and the method for defining sediment passing through the pump. Background Technology

[0002] Pumped storage power stations utilize electricity generated during periods of low electricity load to pump water to an upper reservoir, and release the water to a lower reservoir to generate electricity during periods of high electricity load. They have multiple functions such as peak shaving, valley filling, frequency regulation, phase regulation, energy storage, emergency backup, and black start. They are currently the most technologically mature, economically optimal, and largest-scale green, low-carbon, clean, and flexible power source for power systems, and they work well in conjunction with wind power, solar power, nuclear power, and thermal power.

[0003] According to the design specifications for pumped storage power stations, the hydropower planning and design specifications for pumped storage power stations, and the sediment design specifications for hydropower projects, pumped storage power stations have extremely high requirements for water quality. Sedimentation has always been a key concern in the early design and later operation of such projects. Sediment passing through sandy rivers not only deposits in the reservoir, reducing its effective capacity, but also causes cavitation and erosion of the high-speed turbine blades, resulting in significant wear on the turbine and flow components. Therefore, accurate simulation of the sediment content and gradation passing through the turbine is necessary to implement appropriate sediment control and removal measures.

[0004] Pumped storage power stations operate under complex conditions (including still water, pumping, power generation, and joint operation of two river-type reservoirs), with variable water and sediment conditions (water and sediment exchange between two river-type reservoirs, complex flow patterns near the inlet and outlet, and reciprocating flow). Furthermore, the upper and lower reservoirs of hybrid pumped storage power stations are often cascade reservoirs (the outflow from the upper reservoir is the inflow into the lower reservoir), and water flow is interrupted due to interception. Regarding sediment, the outflow from the upper reservoir affects the calculation of sediment passing through the pump in the lower reservoir. Simultaneously, sediment movement from the lower reservoir, pumped to the upper reservoir, participates in sediment scouring and deposition changes in the upper reservoir, again affecting the outflow from the upper reservoir. This cyclical and coupled effect makes the calculation of sedimentation in the upper and lower reservoirs and sediment passing through the pump in hybrid pumped storage power stations far more complex than that of conventional pumped storage power stations. There is currently no mature numerical simulation algorithm for this in China, so there is an urgent need for a method for calculating the scouring and silting of the upper and lower reservoirs of a hybrid pumped storage power station and for defining the sediment passing through the pump. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for the series connection of scouring and silting in the upper and lower reservoirs of a hybrid pumped storage power station and the definition of sediment passing through the pump. This method simulates sediment deposition in the upper and lower reservoirs of a river-type pumped storage power station, scouring and silting conditions near the inlet and outlet, and sediment content and gradation passing through the pump, taking into account the operating conditions and water and sediment characteristics of the hybrid pumped storage power station.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: Methods for the scouring and sedimentation series connection of upper and lower reservoirs and the delineation of sediment passing through the pumps in hybrid pumped storage power stations include: Obtain data, including the daily scheduling process and various time periods of the hybrid pumped storage power station; Simultaneously, sediment erosion and deposition calculations are performed for both the upper and lower reservoirs, including water flow calculations and sediment calculations; Simulates the exchange of water between the upper and lower reservoirs during pumping / discharging; Output the morphology and distribution of siltation in the upper and lower reservoirs, the sediment content and gradation of the sediment passing through the machine, the siltation volume and sediment discharge ratio of the upper and lower reservoirs, and the siltation distribution at the inlet and outlet cross sections.

[0007] Furthermore, the upper boundary condition of the main stream of the upper and lower reservoirs is the runoff and sediment, and the lower boundary condition is the water level in front of the dam. The cross-section is used to calculate the flow and sediment.

[0008] Furthermore, the methods for determining the inflow and sedimentation processes of the upper and lower reservoirs are as follows: If the upper and lower reservoirs are cascade reservoirs, the inflow and sediment process of the upper reservoir is calculated by inputting the runoff and sediment, while the inflow and sediment process of the lower reservoir is assigned by the outflow and sediment of the upper reservoir after the interaction of the sediment from the pump and the reservoir's scouring and deposition. If the upper and lower reservoirs are not cascade reservoirs, the inflow and sediment process of both reservoirs is calculated by inputting the runoff and sediment.

[0009] Furthermore, the methods for determining the water levels in front of the upper and lower reservoir dams are as follows: If the upper or lower reservoir, or both upper and lower reservoirs, have additional functions such as flood control, power generation, or irrigation in addition to auxiliary pumped storage power generation, the water level in front of the dam of the upper or lower reservoir shall be determined according to the reservoir comprehensive scheduling and operation rules. If the upper or lower reservoir only has pumped storage power generation function, the pumped water volume and runoff inflow shall be counted in each time period according to the daily scheduling process, the reservoir capacity at the end of the time period shall be calculated, and the water level at the end of the time period shall be calculated according to the corresponding reservoir capacity and water level relationship. The average value of the water level at the beginning and end of the time period shall be used as the calculated value of the water level in front of the dam of the corresponding reservoir in that time period. If the calculated water level in front of the dam is higher than the normal water level of the upper and lower reservoirs, then the water level in front of the dam is taken as the normal water level of the upper and lower reservoirs; if the calculated water level in front of the dam is lower than the dead water level of the upper and lower reservoirs, then the water level in front of the dam is taken as the dead water level of the upper and lower reservoirs.

[0010] Furthermore, water flow calculation includes flow rate and water level calculation; Sediment calculations include suspended sediment content and bedload transport rate calculations, riverbed deformation and bed sediment composition calculations, cross-sectional sediment distribution calculations, and cross-sectional correction calculations. Based on the water flow calculation results and sediment calculation results, the output shows the siltation morphology and distribution of the upper and lower reservoirs, the siltation volume and sediment discharge ratio of the upper and lower reservoirs, and the siltation distribution at the inlet and outlet cross sections.

[0011] Furthermore, by numerically simulating the flow patterns near the inlet and outlet, the regions where the flow velocity impact exceeds a certain threshold due to pumping and power generation operations are analyzed, specifically including: Within this area, a flow confluence node is set up upstream of the inlet and outlet, and a flow diversion node is set up downstream. When pumping / releasing water, the amount of water pumped out by the lower and upper reservoirs corresponds one-to-one with the amount of water entering the upper and lower reservoirs. During pumping / draining, the specific outflow and inflow rates at the branching and confluence nodes along the flow path are determined based on the results of local two-dimensional or three-dimensional numerical simulations near the inlet and outlet. Under still water conditions, there are no branching or confluence points, and the flow rate and sediment concentration at each branching and confluence point along the flow path are taken as 0.

[0012] Furthermore, considering that the inflow from the reservoir may be greater than the outflow, the flow rates at each confluence node are calculated according to the following formula (1): Q B = (0.5× Q out )×δ (1); in, Q B For node traffic, Q out Indicates the pumping / draining flow rate. δ This is the flow allocation coefficient.

[0013] Furthermore, a complete pumping / discharge operation is taken as a statistical time period. The total amount of sediment diverted from the lower reservoir diversion node under a complete pumping / discharge operation is calculated. The total amount of sediment diverted is divided by the amount of water pumped out to obtain the sediment content of the pumped water. The total amount of sediment diverted from the upper reservoir diversion node under a complete pumping / discharge operation is calculated. The total amount of sediment diverted is divided by the amount of water pumped in to obtain the sediment content of the discharged water.

[0014] The specific formula is as formula (2): Equation (2); in, S 过机 The amount of sand content in the pumped / discharged water. Indicates the first i Traffic from each distribution node Indicates the first i The sediment content of each diversion node, Indicates the pumping / draining flow rate. n This indicates the total number of splitter nodes.

[0015] Furthermore, the gradation calculation is as shown in equation (3): Equation (3); in, For each group of sediments, the gradation of the sediment content after mechanical processing is determined. Indicates the first The sediment content of the sediment group after passing through the machine. This indicates the total number of sediment groups.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Ensure that both the upper and lower reservoirs are river-type reservoirs, and calculate the water flow and sediment of the upper and lower reservoirs together, and manage the data separately.

[0017] 2. The process of water and sediment leaving the upper reservoir is directly linked to the process of water and sediment entering the lower reservoir; the coupling and feedback relationship between the sediment leaving the upper reservoir, the sediment pumping out, the sediment entering the lower reservoir, and the deformation of the riverbed between the upper and lower reservoirs is simulated.

[0018] 3. To realize the complex daily scheduling process of multiple pumping and one releasing or multiple releasing and one pumping, and the annual changes in reservoir scheduling; 4. Calculate and simulate the water flow and sediment erosion at the inlet and outlet.

[0019] 5. Calculate and simulate the evolution of scouring and sedimentation in the upper and lower reservoirs (including changes in the thalweg line and cross-section), reservoir capacity loss, and sediment discharge ratio.

[0020] 6. Calculate the sediment content and gradation of the sediment passing through the pump in the simulated pumping and power generation conditions. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are intended to explain the invention, but do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram illustrating the interaction between sediment scouring and sedimentation in the upper and lower reservoirs and the sediment passing through the machinery, as described in this invention.

[0022] Figure 2 This is a flowchart of the calculation process for siltation and sedimentation in the upper and lower reservoirs and the calculation process for sediment passing through the machinery, which is part of the present invention.

[0023] Figure 3 This is a simulation diagram of water and sediment exchange near the inlet and outlet during the water pumping process of this invention.

[0024] Figure 4 This is a flowchart illustrating the process of determining the water level in front of the upper and lower reservoir dams in this invention.

[0025] Figure 5 This invention describes the water level process in front of the dam of a hybrid pumped storage reservoir.

[0026] Figure 6 This is a comparison chart of the depth and elevation of the reservoir channel after siltation over different operating years, which is part of the present invention.

[0027] Figure 7 This is a comparison chart of the depth and elevation of the reservoir channel after siltation over different operating years, as presented in this invention.

[0028] Figure 8 This is a cross-sectional sediment distribution diagram of the reservoir inlet and outlet for this invention.

[0029] Figure 9 This is a cross-sectional sediment distribution diagram of the reservoir inlet and outlet for the present invention.

[0030] Figure 10 This is a process diagram showing the sand content during pumping in this invention. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] In related technologies, in river-type upper and lower reservoirs, regarding sediment, the outflow of water and sediment from the upper reservoir affects the calculation of sediment passing through the lower reservoir. Simultaneously, sediment movement from the lower reservoir, pumped to the upper reservoir, participates in the sediment scouring and deposition changes in the upper reservoir, again affecting the outflow of water and sediment from the upper reservoir. This cyclical and coupled effect makes it difficult to obtain results for the joint calculation of sedimentation in the upper and lower reservoirs and sediment passing through the pumps in a hybrid pumped storage power station. This invention, through a method for connecting scouring and deposition in the upper and lower reservoirs of a hybrid pumped storage power station and defining sediment passing through the pumps, can simulate sedimentation in the upper and lower reservoirs, scouring and deposition near the inlet and outlet, and sediment content and gradation passing through the pumps, based on the operating conditions and sediment characteristics of the hybrid pumped storage power station.

[0033] This invention provides a method for the series connection of scouring and silting of upper and lower reservoirs in a hybrid pumped storage power station and for the delineation of sediment passing through the pump, such as... Figure 2 As shown, it includes: Step 1: Obtain data, including the daily scheduling process and time periods of the hybrid pumped storage power station; Step 2: Simultaneously perform sediment scouring and deposition calculations for both the upper and lower reservoirs, including water flow calculations and sediment calculations; Step 3: Simulate the water exchange between the upper and lower reservoirs during pumping / discharging; Step 4: Output the morphology and distribution of siltation in the upper and lower reservoirs, the sediment content and gradation of the sediment passing through the machine, the siltation volume and sediment discharge ratio of the upper and lower reservoirs, and the siltation distribution at the inlet and outlet cross sections.

[0034] In this invention, based on the characteristics of the upper and lower reservoirs of a hybrid pumped storage power station, both the upper and lower reservoirs are river-type reservoirs. The water flow and sediment of the upper and lower reservoirs are calculated together, and data management is carried out separately. The calculation results are reasonable, which can provide a scientific basis and technical support for the water intake and sand control design of hybrid pumped storage power stations and improve the efficiency of reservoirs.

[0035] In this invention, the data also includes measured cross-sectional data of the river channel, bed sediment gradation data, etc.; the scheduling method for maintaining the water level in front of the upper and lower reservoirs of the hybrid pumped storage power station is as follows: Figure 6 As shown.

[0036] This invention can realize complex daily scheduling processes of multiple pumping and one releasing or multiple releasing and one pumping, as well as the annual changes in reservoir scheduling.

[0037] Because the actual operation of a hybrid pumped storage power station may involve complex daily scheduling processes such as multiple pumping and one release, a complete pumping / release operation is considered as a statistical time period. The total amount of sediment diverted from the lower reservoir diversion node under a complete pumping / release operation is calculated, and the total amount of sediment diverted is divided by the amount of water pumped out to obtain the sediment content of the pumped water. Similarly, the total amount of sediment diverted from the upper reservoir diversion node under a complete pumping / release operation is calculated, and the total amount of sediment diverted is divided by the amount of water pumped in to obtain the sediment content of the released water.

[0038] In this invention, the series calculation mode for scouring and silting of the upper and lower reservoirs and the joint calculation mode for sediment passing through the pump are as follows: while taking into account the functions of the existing upper and lower reservoir power stations, the pumping and releasing process can be simulated to realize the series calculation of riverbed deformation of the upper and lower reservoirs and the joint calculation of water and sediment of the upper and lower reservoirs and sediment passing through the pump.

[0039] like Figure 1 As shown, the upper and lower reservoirs and the sediment flow through the pumps interact and influence each other. The sediment deposition process in the upper reservoir affects the sediment flow through the pumps, and the sediment flow through the pumps into the lower reservoir affects the sediment deposition process in the lower reservoir, which in turn affects the sediment flow through the pumps. However, the sediment flow through the pumps then flows into the upper reservoir, affecting the sediment deposition process in the upper reservoir, and so on in a cyclical manner. Furthermore, if the upper and lower reservoirs are cascade reservoirs, the sediment flow through the pumps in the lower reservoir is also affected by the sediment from the water flowing out of the upper reservoir. The specific process for the series calculation of sediment deposition and scouring in the upper and lower reservoirs and the joint calculation of sediment flow through the pumps is as follows: Figure 2 As shown.

[0040] Within the same calculation module, scouring and sedimentation calculations for both the upper and lower reservoirs are performed simultaneously. Specifically, the upper boundary condition of the main stream of the upper and lower reservoirs is runoff and sediment, and the lower boundary condition is the water level in front of the dam. Cross-section calculations are performed for flow and sediment. Flow calculations include flow rate and water level calculations, while sediment calculations include suspended sediment content and bedload transport rate calculations, riverbed deformation and bed sediment composition calculations, cross-sectional sediment distribution calculations, and cross-sectional correction calculations. This allows for the simulation of the scouring and sedimentation evolution of the upper and lower reservoirs, yielding data on changes in the depth of the upper and lower reservoirs, changes in scouring and sedimentation at each cross-section, reservoir capacity loss, and sediment discharge ratio.

[0041] The determination method for the inflow and sediment processes of the upper and lower reservoirs is as follows: If the upper and lower reservoirs are cascade reservoirs, the inflow and sediment process of the upper reservoir is calculated by inputting the inflow and sediment, and the inflow and sediment process of the lower reservoir is assigned by the outflow and sediment of the upper reservoir after the interaction and coupling of sediment passing through the reservoir with the scouring and deposition of the reservoir; if the upper and lower reservoirs are not cascade reservoirs, the inflow and sediment processes of both the upper and lower reservoirs are calculated by inputting the inflow and sediment.

[0042] like Figure 4 As shown, the methods for determining the water levels in front of the upper and lower reservoir dams are as follows: If the upper or lower reservoir, or both upper and lower reservoirs, have additional functions besides auxiliary pumping and storage, such as flood control, power generation, or irrigation, the water levels in front of the upper and lower reservoir dams are determined according to the comprehensive reservoir operation and scheduling rules. If the upper or lower reservoir only has pumping and storage functions, then based on the daily scheduling process, the pumped water volume and runoff inflow are statistically analyzed for each time period, the reservoir capacity at the end of that time period is calculated, and then the water level at the end of the time period is calculated based on the corresponding reservoir capacity-water level relationship. The average of the water levels at the beginning and end of the time period is taken as the calculated value of the corresponding reservoir dam water level for that time period. In addition, the water level is controlled as follows: if the water level is higher than the normal storage level of the upper and lower reservoirs, it is calculated according to the normal storage level of the upper and lower reservoirs; if the water level is lower than the dead water level of the upper and lower reservoirs, it is calculated according to the dead water level of the upper and lower reservoirs.

[0043] In this invention, the upper and lower reservoirs exchange water as pumping / discharging occurs by simulating the flow patterns near the inlet and outlet. The inlet of the pumped-storage power station, corresponding to the opposite flow patterns of power generation and pumping, serves as both an inlet and an outlet, hence the term "inlet / outlet." Both the upper and lower reservoirs of the hybrid pumped-storage power station are equipped with inlets and outlets.

[0044] Specifically, virtual confluence nodes are set up near the inlet and outlet of both the upper and lower reservoirs to simulate the pumping flow. During the pumping and discharge process, the amounts of water and sediment pumped out from the upper and lower reservoirs, the amounts of water and sediment flowing into the upper and lower reservoirs, and the amounts of water pumped out and sediment passing through the pumps are all corresponded one-to-one. The water and sediment calculations for the virtual confluence nodes are performed according to the following method to simulate the pumping / discharge flow near the inlet and outlet: Through two-dimensional or three-dimensional numerical simulation of water flow near the inlet and outlet, the region where the flow velocity impact exceeds a certain threshold due to pumping and power generation operations is analyzed. Virtual flow branching and confluence nodes are then established along the flow path within this region, such as... Figure 3 As shown, a flow convergence node is set up upstream of the inlet and outlet, and a flow divergence node is set up downstream. During pumping and releasing, considering that the inflow from the reservoir may be greater than the pumping flow, the flow rate of each flow convergence node is calculated according to the following formula (1): Q B = (0.5× Q out )×δ (1); in, QB For node traffic, Q out This represents the pumping / draining flow rate, where δ is the flow distribution coefficient.

[0045] To simulate the sediment content entering the hydropower system and the sediment deposition near the inlet and outlet, during pumping and releasing, the sediment content at the confluence nodes of the upper and lower reservoirs is the same as the sediment content of the previous pumping / releasing operation, and the sediment content at the diversion nodes of the upper and lower reservoirs is the sediment content of the corresponding upstream section of that diversion node. Under still water conditions with no diversion or confluence, the diversion flow rate and sediment content are set to 0.

[0046] In this invention, the sand content and gradation are calculated according to the following method: Since the actual operation of a hybrid pumped storage power station may involve complex daily scheduling processes of pumping and releasing multiple times, a complete pumping / releasing operation is taken as a statistical time period. The total amount of sediment diverted from the lower reservoir diversion node under a complete pumping / releasing operation is calculated. The total amount of sediment diverted is divided by the amount of water pumped out to obtain the sediment content of the pumped water. The total amount of sediment diverted from the upper reservoir diversion node under a complete pumping / releasing operation is calculated. The total amount of sediment diverted is divided by the amount of water pumped in to obtain the sediment content of the discharged water. The specific formula is shown in formula (2).

[0047] Equation (2); in, S 过机 The amount of sand in the machine. Q i Indicates the first i Traffic from each distribution node S i Indicates the first i The sediment content of each diversion node, Q out Indicates the pumping / draining flow rate. i Indicates the first i 1 node n This indicates the total number of splitter nodes.

[0048] The gradation calculation is as shown in equation (3): Equation (3); in, For each group of sediments, the gradation of the sediment content after mechanical processing is determined. Indicates the first The sediment content of the sediment group after passing through the machine. This indicates the total number of sediment groups.

[0049] In addition, considering that the reservoir scheduling mode of the hybrid pumped storage power station may change throughout the year, time variables TT0 and TT1 are set to store the applicable start and end times of the reservoir scheduling mode. When the program calculation time exceeds TT1, the new reservoir scheduling mode needs to be read in, and the number of daily pumping / releasing time periods, operating conditions, and pumping / releasing water volume need to be recalculated, so as to realize the simulation of the changes in the reservoir scheduling process throughout the year.

[0050] The results were statistically calculated, including the morphology and distribution of sedimentation in the upper and lower reservoirs, the sediment content and gradation of sediment passing through the machinery, the amount of sedimentation in the upper and lower reservoirs and the sediment discharge ratio, and the sedimentation distribution in the cross-sections of the inlet and outlet.

[0051] In a specific embodiment of the present invention, the calculation results are shown in Tables 1-2 and... Figure 5-10 As shown in Table 1. Calculation results of sediment deposition and sediment discharge ratio of the upper and lower reservoirs of a hybrid pumped storage power station at different operating years.

[0052] Table 2. Statistical table of sand content passing through the machine during different operating periods.

[0053] In summary, according to the embodiments provided by the present invention, the numerical simulation of water and sediment in a hybrid chamber pumped storage power station can achieve the following functions: 1. Ensure that both the upper and lower reservoirs are river-type reservoirs, and link the water flow and sediment of the upper and lower reservoirs, and manage the data separately; 2. The process of water and sediment outflow from the upper reservoir is directly linked to the process of water and sediment inflow into the lower reservoir; the coupling and feedback relationship between the four processes of sediment outflow from the upper reservoir, sediment pumping, sediment inflow into the lower reservoir, and riverbed deformation of the upper and lower reservoirs is simulated. 3. To realize the complex daily scheduling process of multiple pumping and one releasing or multiple releasing and one pumping, and the annual changes in reservoir scheduling; 4. Calculate and simulate the water flow and sediment erosion at the inlet and outlet; 5. Calculate and simulate the evolution of scouring and sedimentation in the upper and lower reservoirs (including changes in the thalweg line and cross-section), reservoir capacity loss due to sedimentation, and sediment discharge ratio; 6. Calculate the sediment content and gradation of the sediment passing through the pump in the simulated pumping and power generation conditions.

[0054] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for the series connection of scouring and silting of upper and lower reservoirs and the delineation of sediment passing through the pump in a hybrid pumped storage power station, characterized in that, include: Obtain data, including the daily scheduling process and various time periods of the hybrid pumped storage power station; Simultaneously, sediment erosion and deposition calculations are performed for both the upper and lower reservoirs, including water flow calculations and sediment calculations; Simulates the exchange of water between the upper and lower reservoirs during pumping / discharging; Output the morphology and distribution of sedimentation in the upper and lower reservoirs, the sediment content and gradation of the sediment passing through the machine, the amount of sedimentation in the upper and lower reservoirs and the sediment discharge ratio, and the sedimentation distribution at the inlet and outlet cross sections; Among them, the upper boundary condition of the main stream of the upper and lower reservoirs is the runoff and sediment, and the lower boundary condition is the water level in front of the dam. The cross section is used to calculate the flow and sediment. The methods for defining the inflow and sedimentation processes of the upper and lower reservoirs are as follows: If the upper and lower reservoirs are cascade reservoirs, the inflow water and sediment process of the upper reservoir is calculated by inputting the runoff inflow water and sediment, while the inflow water and sediment process of the lower reservoir is assigned by the outflow water and sediment of the upper reservoir after the interaction between the sediment passing through the reservoir and the scouring and deposition. If the upper and lower reservoirs are not cascade reservoirs, the inflow water and sediment process of both the upper and lower reservoirs is calculated by inputting the runoff inflow water and sediment. The methods for determining the water levels in front of the upper and lower reservoir dams are as follows: If the upper or lower reservoir, or both upper and lower reservoirs, have additional functions such as flood control, power generation, or irrigation in addition to auxiliary pumping and storage, the water level in front of the dam of the upper or lower reservoir shall be determined according to the reservoir comprehensive scheduling and operation rules. If the upper or lower reservoir only has pumping and storage functions, the pumped water volume and runoff inflow shall be counted in each time period according to the daily scheduling process, the reservoir capacity at the end of the time period shall be calculated, and the water level at the end of the time period shall be calculated according to the corresponding reservoir capacity and water level relationship. The average value of the water level at the beginning and end of the time period shall be used as the calculated value of the water level in front of the dam of the corresponding reservoir in that time period. If the calculated water level in front of the dam is higher than the normal water level of the upper and lower reservoirs, then the water level in front of the dam is taken as the normal water level of the upper and lower reservoirs; if the calculated water level in front of the dam is lower than the dead water level of the upper and lower reservoirs, then the water level in front of the dam is taken as the dead water level of the upper and lower reservoirs.

2. The method for siltation and sedimentation series connection of upper and lower reservoirs and sediment boundary of the pumping station according to claim 1, characterized in that: Water flow calculation includes flow rate and water level calculation; Sediment calculations include suspended sediment content and bedload transport rate calculations, riverbed deformation and bed sediment composition calculations, cross-sectional sediment distribution calculations, and cross-sectional correction calculations. Based on the water flow calculation results and sediment calculation results, the output shows the siltation morphology and distribution of the upper and lower reservoirs, the siltation volume and sediment discharge ratio of the upper and lower reservoirs, and the siltation distribution at the inlet and outlet cross sections.

3. The method for siltation and sedimentation series connection of upper and lower reservoirs and sediment boundary of the pumping station according to claim 1, characterized in that: Numerical simulations of the flow patterns near the inlet and outlet were used to analyze areas where the flow velocity impact exceeded a threshold due to pumping and power generation operations. Specifically, these areas included: Within this area, a flow confluence node is set up upstream of the inlet and outlet, and a flow diversion node is set up downstream. When pumping / releasing water, the amount of water pumped out by the lower and upper reservoirs corresponds one-to-one with the amount of water entering the upper and lower reservoirs. During pumping / draining, the specific outflow and inflow rates at the branching and confluence nodes along the flow path are determined based on the results of local two-dimensional or three-dimensional numerical simulations near the inlet and outlet. Under still water conditions, there are no branching or confluence points, and the flow rate and sediment concentration at each branching and confluence point along the flow path are taken as 0.

4. The method for siltation and sedimentation series connection of upper and lower reservoirs and sediment boundary of the pumping station according to claim 3, characterized in that: Considering that the inflow from the reservoir may be greater than the outflow, the flow rates at each confluence node are calculated according to the following formula (1): Q B = (0.5× Q out )×δ (1); in, Q B For node traffic, Q out Indicates the pumping / draining flow rate. δ This is the flow allocation coefficient.

5. The method for siltation and sedimentation series connection of upper and lower reservoirs and sediment boundary of pumping station according to claim 1, characterized in that: A complete pumping / discharging operation is taken as a statistical time period. The total amount of sediment diverted from the diversion node of the lower reservoir under a complete pumping / discharging operation is calculated. The total amount of sediment diverted is divided by the amount of water pumped out to obtain the sediment content of the pumped water. The total amount of sediment diverted from the upper reservoir diversion node under a complete pumping / discharge operation is calculated. Dividing this total amount of sediment diverted by the pumped water volume gives the sediment content of the discharged water. The specific formula is as formula (2): Equation (2); in, S 过机 The amount of sand content in the pumped / discharged water. Indicates the first i Traffic from each distribution node Indicates the first i The sediment content of each diversion node, Q out Indicates the pumping / draining flow rate. n This indicates the total number of splitter nodes.

6. The method for siltation and sedimentation linkage of upper and lower reservoirs and sediment boundary delineation in a hybrid pumped storage power station according to claim 1, characterized in that, The gradation calculation is as shown in equation (3): Equation (3); in, For each group of sediments, the gradation of the sediment content after mechanical processing is determined. Indicates the first The sediment content of the sediment group after passing through the machine. This indicates the total number of sediment groups.

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