Tidal power generation system with pumped storage function and cooperative operation with offshore wind power

Abstract

The invention provides a tidal power generation system having a pumped storage function and cooperatively operating with offshore wind power. The system integrates a double-reservoir tidal power station and a variable-speed pumped storage power station, adopts an upper reservoir and a lower reservoir which are shared, and has the capability of cooperatively operating with an offshore wind power plant. The pumped storage power station achieves interconnection of the upper reservoir, the lower reservoir and the open sea through water diversion pipelines, the water flow path is controlled through a pipeline valve, the power generation mode and the water pumping mode are flexibly switched, the tidal power station flexibly reduces the power generation power by controlling the gate opening degree of the power station, and therefore the services of peak load shifting and power fluctuation stabilizing are provided for a power grid. Compared with a common double-reservoir type tidal power station, only one variable-speed pumped storage unit is additionally arranged in the system, the construction cost of water conservancy facilities is slightly increased, the capacity of cooperative operation with offshore wind power is obtained, and the functions of providing peak load shifting and power fluctuation stabilizing services for a power grid are achieved; meanwhile, flat-tide-level water pumping is supported, and the power generation capacity and economic benefits can be further improved.

Description

Technical Field

[0001] This invention relates to the field of renewable energy power generation technology, specifically to a tidal power generation system that combines pumped storage with offshore wind power. Background Technology

[0002] Tidal power plants generate electricity using tidal energy produced by the rise and fall of tides. Their working principle is similar to traditional hydroelectric power: seawater is stored in a reservoir during high tide, and then the difference in water level between high and low tides during low tide drives a turbine to rotate, which in turn drives a generator to produce electricity. Tidal power generation requires sufficient tidal amplitude and suitable coastal topography. Types of tidal power plants include single-reservoir unidirectional power plants, single-reservoir bidirectional power plants, and double-reservoir continuous power plants, each operating under different tidal conditions. While tidal power generation has advantages such as high predictability and stable resources, it is limited by the tidal cycle, resulting in intermittent power generation. Furthermore, tidal energy density is low, making it difficult for a single tidal power system to meet large-scale electricity demand. Traditional tidal power systems can only generate electricity using tidal changes, lacking coordination mechanisms with other renewable energy sources, and cannot effectively regulate and store energy during periods of insufficient or excessive electricity demand.

[0003] Pumped-storage hydroelectric power plants generate electricity by pumping water from a low-level reservoir to a high-level reservoir during periods of low electricity demand and releasing the water during periods of high demand. The reversible pump-turbine design allows pumped-storage power plants to flexibly switch between power generation and pumping modes, effectively shaving off peak loads and mitigating power fluctuations in the power system. They can also serve as backup power sources, operating in conjunction with other power generation methods. However, traditional pumped-storage power plants typically require construction in terrain with significant elevation differences, involving large-scale excavation and dam construction, resulting in high costs.

[0004] Wind power, as an important renewable energy source, is significantly affected by changes in wind speed, exhibiting pronounced power fluctuations. These fluctuations can impact grid stability, thus necessitating its combination with other stable power generation methods to mitigate these fluctuations.

[0005] In summary, individual power plants cannot meet user demand. By combining pumped storage power plants with dual-reservoir tidal power generation, and utilizing existing dual-reservoir tidal power plant infrastructure, not only is the additional occupation of land and natural resources reduced, but construction costs and environmental impact are also significantly lowered. Simultaneously, coordinated operation with offshore wind power can smooth out wind power fluctuations, enabling better response to grid dispatch instructions, improving the utilization efficiency of renewable energy, and providing a more stable and efficient power supply. Summary of the Invention

[0006] The purpose of this invention is to provide a tidal power generation system with pumped storage function that can operate in conjunction with offshore wind power, so as to overcome the limitations of existing technologies such as tidal power generation, pumped storage power stations and wind power generation, and realize the function of peak shaving and valley filling and power fluctuation smoothing of the power grid.

[0007] This invention integrates a dual-reservoir tidal power station and a variable-speed pumped storage power station, and has the ability to coordinate with offshore wind farms. The variable-speed pumped storage power station shares an upper reservoir (high-level reservoir) and a lower reservoir (low-level reservoir) with the dual-reservoir tidal power station. The variable-speed pumped storage units connect the upper and lower reservoirs to the open sea through water diversion pipelines. Both the tidal generator units and the variable-speed pumped storage units are arranged in the powerhouse between the upper and lower reservoirs.

[0008] The variable-speed pumped-storage power station includes an upper and lower reservoir shared with the dual-reservoir tidal power station, a pumped-storage powerhouse built on a dam between the upper and lower reservoirs, variable-speed pumped-storage units installed in the powerhouse, and their connected water intake pipelines and valves. The water intake pipelines interconnect the upper and lower reservoirs with the ocean. By controlling the valves, the flow path of water passing through the variable-speed pumped-storage units can be switched. When the variable-speed pumped-storage units operate in power generation mode, the water flow can be selected to flow from the upper reservoir to the lower reservoir, or from the open sea to the lower reservoir. When the variable-speed pumped-storage units operate in pumping mode, the water flow can be selected to flow from the lower reservoir to the upper reservoir, or from the open sea to the upper reservoir.

[0009] The system of this invention supports multiple operating modes:

[0010] (1) Tidal generator sets operate at reduced power, which is suitable for situations where there is a small amount of excess power in the system;

[0011] (2) The tidal generator set is temporarily shut down and the variable speed pumped storage unit pumps water, which is suitable for situations where the system has a serious power surplus.

[0012] (3) Variable speed pumped storage units can compensate for power generation deficits and are suitable for situations where power generation is insufficient.

[0013] (4) Variable speed pumped storage units can pump water from the ocean to the upper reservoir at low tide, which is suitable for situations where the system's power generation is significantly insufficient and the water levels of the ocean and the upper reservoir are close.

[0014] The beneficial effects of the present invention include the following:

[0015] (1) Comprehensive utilization of renewable energy resources: By combining tidal power generation, pumped storage and offshore wind power, we can make full use of marine and wind energy resources, improve energy efficiency and reduce dependence on traditional energy.

[0016] (2) Smoothing power fluctuations: The flexibility of variable speed pumped storage units enables the system to respond quickly to changes in grid demand, effectively smoothing power fluctuations in wind power generation and improving the stability and reliability of the power system.

[0017] (3) Enhance power generation capacity and economic benefits: When the water level in the open sea and the upper reservoir is close to the slack tide level, the variable speed pumped storage unit can pump a large amount of water by consuming less electricity. By taking advantage of the relative water level changes during high tide and low tide, it can automatically acquire and store a large amount of potential energy. Compared with ordinary dual-reservoir tidal power stations, this system only adds one variable speed pumped storage unit, and the construction cost of water conservancy facilities increases very little, effectively enhancing the power generation capacity and economic benefits of the tidal power generation system.

[0018] (4) Flexible grid dispatch: The system can flexibly adjust the operating status of each power generation mode according to the grid load, realize peak shaving and valley filling, effectively solve the problem of power surplus or shortage, and improve the grid dispatch capability and operating efficiency.

[0019] (5) Reduced construction costs and environmental impact: Compared with traditional pumped storage power stations, this system utilizes existing tidal power generation infrastructure, avoiding additional land occupation and large-scale dam construction, while reducing environmental impact and construction costs. Attached Figure Description

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings.

[0021] Figure 1 This is a plan view of the tidal power generation system with pumped storage function that operates in conjunction with offshore wind power in this invention.

[0022] Figure 2 This is a cross-sectional schematic diagram of the dual-reservoir tidal power station in this invention.

[0023] Figure 3 This is a schematic diagram of the water intake pipeline and pipeline gate structure of the variable speed pumped storage power station in this invention.

[0024] In the diagram: 1. Intake gate of the upper reservoir; 2. Outlet gate of the lower reservoir; 3. Upper reservoir; 4. Lower reservoir; 5. Double-reservoir tidal power plant; 6. Pumped storage power plant; 7. Tidal generator unit; 8. Variable speed pumped storage unit; 9. Power plant gate; 10. Upper reservoir interface of pumped storage unit; 11. Lower reservoir interface of pumped storage unit; 12. Offshore interface of pumped storage unit; 13. Dam; 14. Offshore wind farm; 15. Upper reservoir interface valve of pumped storage unit; 16. Lower reservoir interface valve of pumped storage unit; 17. First valve of offshore interface of pumped storage unit; 18. Second valve of offshore interface of pumped storage unit; 19. Connecting pipeline. Detailed Implementation

[0025] It should be noted that the terms "first," "second," etc., used in this application are for descriptive purposes only and should not be construed as indicating their relative importance or implicitly indicating the number of technical features described.

[0026] like Figure 1 , Figure 2 and Figure 3 As shown, this invention designs a tidal power generation system with pumped storage capability that operates in conjunction with offshore wind power. This system integrates a dual-reservoir tidal power station and a variable-speed pumped storage power station, sharing an upper reservoir 3 and a lower reservoir 4, and has the capability to coordinate with an offshore wind farm 14. The dual-reservoir tidal power station mainly includes an upper reservoir 3 and a lower reservoir 4 with surrounding dikes, an upper reservoir intake gate 1 and a lower reservoir discharge gate 2, a power plant 5 and a power station gate 9 built on a dike 13 between the upper and lower reservoirs, and tidal generator units 7 installed within the power plant. The upper reservoir 3 and lower reservoir 4 are connected to the open sea via the upper reservoir intake gate 1 and the lower reservoir discharge gate 2, respectively. The variable-speed pumped-storage power station includes an upper reservoir 3, a lower reservoir 4, a pumped-storage powerhouse 6 built on a dam 13 between the upper reservoir 3 and the lower reservoir 4, a variable-speed pumped-storage unit 8 installed in the powerhouse, and its connected water intake pipelines and valves. Specifically, the water intake pipeline includes an upper reservoir interface 10 for the pumped-storage unit, a lower reservoir interface 11 for the pumped-storage unit, an offshore interface 12 for the pumped-storage unit, and a connecting pipeline 19. The pipeline valves include an upper reservoir interface valve 15 for the pumped-storage unit, a lower reservoir interface valve 16 for the pumped-storage unit, a first offshore interface valve 17 for the pumped-storage unit, and a second offshore interface valve 18 for the pumped-storage unit. The water intake pipelines enable interconnection between the upper reservoir 3, the lower reservoir 4, and the ocean. By controlling the opening and closing of the pipeline valves, the flow path of water through the variable-speed pumped-storage unit 8 can be switched.

[0027] The dual-reservoir tidal power station operates normally by utilizing tidal patterns. When the tide level is higher than that of the upper reservoir (3), the upper reservoir intake gate 1 opens to allow the tide to flow in, increasing the water level; at this time, the lower reservoir discharge gate 2 closes. When the sea level drops to the same level as the upper reservoir (3), the upper reservoir intake gate 1 closes. When the tide level is lower than that of the lower reservoir (4), the lower reservoir discharge gate 2 opens to drain water, causing the water level to drop. When the tide level rises back to the same level as the lower reservoir (4), the lower reservoir discharge gate 2 closes. The power station gate 9 remains open, maintaining a constant headwater difference between the upper reservoir (3) and the lower reservoir (4), thus enabling continuous power generation.

[0028] The elevations of the inlet and outlet of the water diversion pipeline at both the upper reservoir 3 and the lower reservoir 4 are below the dead water level.

[0029] Furthermore, the tidal power generation system with pumped storage function that operates in conjunction with offshore wind power supports the following multiple operating modes.

[0030] Mode 1 (Pumped Storage Standby, Dual-Reservoir Tidal Power Station Power Reduction): When the generating power of offshore wind farm 14 is less than the grid dispatch power, and the overall system generates excess power, and the water level difference between the upper reservoir 3 and the open sea is large, the opening of the power station gate 9 is controlled to reduce the flow, causing the tidal generator unit 7 to operate at reduced power; all pipeline valves are closed, including the pumped storage unit upper reservoir interface valve 15, the pumped storage unit lower reservoir interface valve 16, the pumped storage unit open sea interface first valve 17, and the pumped storage unit open sea interface second valve 18, putting the variable speed pumped storage unit 8 into standby mode. In this mode, the power reduction of the dual-reservoir tidal power station is the system's excess power.

[0031] Mode 2 (Pumped Storage at Ebb Tide, Dual-Reservoir Tidal Power Station Power Reduction): When the power generation of offshore wind farm 14 is less than the dispatch power, and the overall system power generation is excessive, and the water level of upper reservoir 3 is close to that of the open sea, the opening of the power station gate 9 is controlled to reduce the flow, causing the tidal generator unit 7 to operate at reduced power. The variable-speed pumped storage unit 8 consumes some electrical energy for pumping at ebb tide, opening the second valve 18 at the offshore interface of the pumped storage unit and the valve 15 at the upper reservoir interface of the pumped storage unit, and closing the valve 16 at the lower reservoir interface of the pumped storage unit and the first valve 17 at the offshore interface of the pumped storage unit. The water flow path is from the open sea to the upper reservoir 3. At this time, pumping at ebb tide consumes less energy but has a large pumping volume. When the tide recedes, the water level of the open sea decreases, and the water pumped into the upper reservoir automatically reaches a relatively high position. The water level difference between the upper reservoir and the open sea at ebb tide, as well as the difference between the upper reservoir and the lower reservoir, can bring additional potential energy.

[0032] Mode 3 (Pumped Storage Pumping at Equilibrium Level, Dual-Reservoir Tidal Power Station Shutdown): When the power generation of offshore wind farm 14 exceeds the dispatch power and the system generates excess power, and the water level of upper reservoir 3 is close to that of the open sea, the power station gate 9 is closed, causing the tidal generator unit 7 to shut down. The variable speed pumped storage unit 8 consumes excess power to pump water at equilibrium level, and the opening and closing of pipeline valves are the same as in Mode 2.

[0033] Mode 4 (High-lift pumped storage, dual-reservoir tidal power station shutdown): When the power generation of offshore wind farm 14 exceeds the dispatch power and the system generates excess power, and there is a large difference in water level between the upper reservoir 3 and the open sea, the power station gate 9 is closed, causing the tidal generator unit 7 to shut down; the excess power of the variable speed pumped storage unit 8 is used for high-lift pumping, the upper reservoir interface valve 15 of the pumped storage unit and the reservoir inlet and outlet water pipe valve 16 are opened, and the first valve 17 of the pumped storage unit's open sea interface and the second valve 18 of the pumped storage unit's open sea interface are closed. The water flow path is from the lower reservoir 4 to the upper reservoir 3.

[0034] Mode 5 (Pumped Storage Large-Scale Power Supplement, Tidal Power Generation Normal): When there is a significant power generation deficit in the system, the dual-reservoir tidal power station operates normally; the variable-speed pumped storage unit 8 generates a large amount of power to compensate for the deficit. If the water level difference between the upper reservoir 3 and the lower reservoir 4 is greater than the water level difference between the open sea and reservoir 4, the upper reservoir interface valve 15 of the pumped storage unit and the reservoir inlet / outlet pipeline valve 16 are opened, and the first valve 17 of the pumped storage unit's open sea interface and the second valve 18 of the pumped storage unit's open sea interface are closed. The water flow path is from the upper reservoir 3 to the lower reservoir 4. If the water level difference between the upper reservoir 3 and the lower reservoir 4 is less than the water level difference between the open sea and reservoir 4, the reservoir inlet / outlet pipeline valve 16 and the first valve 17 of the pumped storage unit's open sea interface are opened, and the upper reservoir interface valve 15 of the pumped storage unit and the second valve 18 of the pumped storage unit's open sea interface are closed. The water flow path is from the open sea to the lower reservoir 4.

[0035] Mode 6 (small-scale pumped storage power supplement, normal tidal power generation): When the system's power generation is slightly insufficient and the difference between the upper reservoir 3 and the open sea water level is large, the dual-reservoir tidal power station operates normally; the variable-speed pumped storage unit 8 generates power to compensate for the shortfall, and the opening and closing of pipeline valves are the same as in Mode 5.

[0036] Mode 7 (Pumped Storage at Equilibrium Level, Normal Tidal Power Generation): When the system's power generation is slightly insufficient and the water level of the upper reservoir 3 is close to that of the open sea, the dual-reservoir tidal power station operates normally; the variable-speed pumped storage unit 8 pumps water at equilibrium level, and the opening and closing of the pipeline valves are the same as in Mode 2. Since the power deficit is within the grid's acceptable range at this time, the efficiency of using the pumped storage unit for power generation is not as good as the efficiency of using it for pumping and storing potential energy.

[0037] In summary, this invention can achieve peak shaving and valley filling of the power grid and smoothing of wind power fluctuations through the selection and switching of various modes. By adding pumped storage units and pipelines to the existing dual-reservoir tidal power station layout, the construction cost of water conservancy facilities increases only slightly, while gaining the ability to operate in conjunction with offshore wind power and improving the comprehensive utilization efficiency of resources. When the water levels in the open sea and the upper reservoir are close to the slack tide level, the variable-speed pumped storage units can pump a large amount of water with relatively low power consumption. When the tide recedes, the water level in the open sea decreases, and the water pumped into the upper reservoir is automatically placed at a relatively higher position, thereby gaining additional potential energy. This process not only greatly reduces energy loss but also effectively enhances the power generation capacity and economic benefits of the power generation system.

Claims

1. A tidal power system with pumped storage function and coordinated operation with offshore wind power, integrated by an existing double reservoir tidal power station and a variable speed pumped storage power station established on the basis of the setting of the former, and having the ability to coordinate with an offshore wind farm (14), characterized in that, The double-reservoir tidal power station and the variable-speed pumped storage power station share the upper reservoir (3) and the lower reservoir (4), the tidal generator set (7) and the variable-speed pumped storage set (8) are arranged in the powerhouse between the upper reservoir (3) and the lower reservoir (4), the variable-speed pumped storage set (8) is connected with the upper reservoir (3), the lower reservoir (4) and the outer sea through the water diversion pipeline, and the water flow path of the variable-speed pumped storage set can be switched by controlling the pipeline valve; The double-reservoir tidal power station mainly comprises the upper reservoir (3) and the lower reservoir (4) provided with a dam, the upper reservoir inlet gate (1) and the lower reservoir outlet gate (2), the double-reservoir tidal power station powerhouse (5) and the power station gate (9) established on the dam (13) between the upper reservoir and the lower reservoir, and the tidal generator set (7) installed in the double-reservoir tidal power station powerhouse (5); The variable-speed pumped storage power station comprises the upper reservoir (3) and the lower reservoir (4) shared by the double-reservoir tidal power station, the pumped storage power station powerhouse (6) established on the dam (13) between the upper reservoir (3) and the lower reservoir (4), the variable-speed pumped storage set (8) installed in the pumped storage power station powerhouse (6) and the water diversion pipeline and the pipeline valve connected with the variable-speed pumped storage set (8); The water diversion pipeline comprises the pumped storage set upper reservoir interface (10), the pumped storage set lower reservoir interface (11), the pumped storage set outer sea interface (12) and the connecting pipeline (19), and the pipeline valve comprises the pumped storage set upper reservoir interface valve (15), the pumped storage set lower reservoir interface valve (16), the pumped storage set outer sea interface first valve (17) and the pumped storage set outer sea interface second valve (18).

2. The tidal power system with pumped storage function and coordinated operation with offshore wind power according to claim 1, characterized in that, The water flow path is as follows: When the variable-speed pumped storage set (8) works in the power generation mode, the upper reservoir (3) and the lower reservoir (4) are connected through the water diversion pipeline, the water in the upper reservoir (3) is discharged to the lower reservoir (4) to support the variable-speed pumped storage set (8) to generate power, or the outer sea and the lower reservoir (4) are connected through the water diversion pipeline, the water in the outer sea is discharged to the lower reservoir (4) to support the variable-speed pumped storage set (8) to generate power; when the variable-speed pumped storage set works in the water pumping mode, the lower reservoir (4) and the upper reservoir (3) are connected through the water diversion pipeline, the water in the lower reservoir (4) is pumped to the upper reservoir (3) to support the variable-speed pumped storage set (8) to pump water, or the outer sea and the upper reservoir (3) are connected through the water diversion pipeline, the water in the outer sea is pumped to the upper reservoir (3) to support the variable-speed pumped storage set (8) to pump water.

3. The tidal power system with pumped storage function and coordinated operation with offshore wind power according to claim 1, characterized in that, The supported multiple cooperative operation modes are as follows: Mode one (pumped storage standby, double-reservoir tidal power station power reduction): the tidal generator set (7) works in the power reduction mode, and the variable-speed pumped storage set (8) is in the standby state, which is suitable for the case that the power generation of the offshore wind farm (14) is less than the power grid dispatching power, the overall power generation of the system is excessive, and the water level difference between the upper reservoir (3) and the outer sea is large; Mode two (pumping to tide level, double reservoir tidal power station power reduction): the tidal generator set (7) to reduce power operation, variable speed pumped storage unit (8) to consume part of the power from the sea to the upper reservoir (3) pumping tide level, suitable for when the offshore wind farm (14) power is less than the dispatching power, and the system overall power surplus, and the upper reservoir (3) and the sea level is similar to the case; Mode three (pumping to tide level, double reservoir tidal power station shutdown): the tidal generator set (7) to stop, variable speed pumped storage unit (8) to consume excess power from the sea to the upper reservoir (3) pumping tide level, suitable for when the offshore wind farm (14) power is greater than the dispatching power, and the upper reservoir (3) and the sea level is similar to the case; Mode four (pumping to high lift pumping, double reservoir tidal power station shutdown): the tidal generator set (7) to stop, variable speed pumped storage unit (8) to consume excess power from the lower reservoir (4) to the upper reservoir (3) high lift pumping, suitable for when the offshore wind farm (14) power is greater than the dispatching power, and the upper reservoir (3) and the sea level difference is larger to the case; Mode five (pumping to large amount of power compensation, tidal normal power generation): the tidal generator set (7) normal operation, variable speed pumped storage unit (8) large power generation to compensate for the shortage, suitable for when the system power has a large shortage, if the upper reservoir (3) and the lower reservoir (4) water level difference than the sea and the lower reservoir (4) water level difference is large, variable speed pumped storage unit (8) from the upper reservoir (3) to the lower reservoir (4) water power generation; if the upper reservoir (3) and the lower reservoir (4) water level difference than the sea and the lower reservoir (4) water level difference is small, variable speed pumped storage unit (8) from the sea to the lower reservoir (4) water power generation; Mode six (pumping to small amount of power compensation, tidal normal power generation): the tidal generator set (7) normal operation, variable speed pumped storage unit (8) small power generation to compensate for the shortage, suitable for when the system power is small and the upper reservoir (3) and the sea level difference is large to the case, the water discharge path is the same as mode five; Mode seven (pumping to tide level, tidal normal power generation): the tidal generator set (7) normal operation, variable speed pumped storage unit (8) pumping tide level, suitable for when the system power is small and the upper reservoir (3) and the sea level is similar to the case, since the power shortage in the grid acceptance range, variable speed pumped storage unit (8) can be pumped to tide level, play the benefits of pumped storage unit for pumping storage potential.

4. The tidal power system with pumped storage function and coordinated operation with offshore wind power according to claim 3, characterized in that, Supporting pumping to tide level, that is, when the sea and the upper reservoir water level is close, the variable speed pumped storage unit consumes small amount of power to pump large amount of water to the upper reservoir, when the ebb tide, the sea level is lowered, the water pumped into the upper reservoir is automatically at a relatively high position, obtaining additional potential energy.

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