A structure, method, and efficiency calculation method for improving the efficiency of a water turbine using pumped storage.

Abstract

This invention relates to a structure, method, and efficiency calculation method for improving the efficiency of a hydroelectric turbine using pumped storage, belonging to the field of water conservancy engineering technology. It consists of a generator-motor unit, a pump-turbine unit, and a tailrace pipe. When there is excess electricity in the power grid, the pump-turbine unit can be activated to pump water from the downstream river to the upstream reservoir, consuming the excess electricity in the grid. This ensures that the actual output of the turbine unit is not reduced, maintaining its high-efficiency operating range and improving turbine efficiency. When there is insufficient electricity in the power grid and an increase in the hydroelectric power station's output is required, the pump-turbine unit can be activated to generate electricity, supplementing the grid and alleviating the power shortage, enabling flexible scheduling of the hydroelectric power station. This invention improves the operating efficiency of the turbine unit without reducing its output, reduces water consumption, and increases the power generation efficiency of the hydroelectric power station.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering technology, specifically relating to a structure, method, and efficiency calculation method for improving the efficiency of a water turbine by using pumped storage. Background Technology

[0002] Turbine efficiency is a key factor affecting the economic benefits and sustainable development of hydropower stations. Currently, through optimized design, regular maintenance, and improved operation and management, turbine efficiency can be significantly improved, enhancing the overall power generation capacity and economic benefits of hydropower stations. However, each turbine design has a specific rated head and flow range. Within this range, turbine efficiency is typically high, with some large and medium-sized turbines achieving efficiencies exceeding 95%. If the turbine's operating head deviates significantly from its rated head and flow, its efficiency will drastically decrease, sometimes to as low as 30%. Even with new turbines, at the rated head, when the turbine output is only 50% of its rated power, its efficiency will drop to around 80%; if the head is lower than the rated head, its efficiency will continue to decline. In reality, many hydropower stations experience low reservoir water levels during the later stages of the dry season and during the flood season due to flood control requirements, leading to actual turbine power output lower than the rated power. Therefore, the turbine units of hydropower stations operate at relatively low efficiency for certain periods, impacting the station's power generation. Meanwhile, as time goes by, water turbines also face aging issues, leading to a continuous decrease in efficiency and affecting the power generation capacity of hydropower stations. Furthermore, low turbine operating efficiency can result in excessive unit vibration, worsening operating conditions and further reducing efficiency, while also impacting the safety of the turbine piers. Therefore, improving turbine efficiency and increasing hydropower station power generation is a key measure to alleviate my country's energy shortage. Currently, water turbine design levels are already very high, with efficiencies exceeding 90%. Relying solely on optimized turbine design and regular maintenance is unlikely to significantly improve efficiency further. Therefore, new methods and approaches are urgently needed to enhance water turbine efficiency. Summary of the Invention

[0003] To address the problem of significant efficiency drops in existing hydroelectric turbines when their actual power output is far below their rated power, this invention proposes a structure, method, and efficiency calculation method for improving turbine efficiency using pumped storage. This method involves selecting one or two existing turbine units from a hydroelectric power station and converting them into pump-turbine units, while also converting their generator sets into generator-motor units, thus realizing the hydroelectric power station's pumped storage and power generation functions. When the hydroelectric power station needs to reduce its output, the pumping function of the generator-motor unit can be activated to consume excess electricity from the grid, thereby maintaining the actual output of the turbines and ensuring that the turbine units operate near their rated power, thus improving turbine efficiency. When the hydroelectric power station needs to increase its output, the generator-motor unit can be activated to supplement the grid with electricity, alleviating power shortages.

[0004] The technical solution adopted in this invention is: a structure for improving the efficiency of a water turbine by using pumped storage, comprising a generator set 1, a pump-turbine unit 2, a tailrace pipe 3, a pressure steel pipe 5, a turbine generator set 6, and a control system 7. The generator set 1 and the pump-turbine unit 2 are connected by the same main shaft, and the inlet of the pump-turbine unit 2 is connected to the end of the pressure steel pipe 5. The outlet of the pump-turbine unit 2 is connected to the tailrace pipe 3, and the tailrace pipe 3 is connected to the downstream river channel. The generator set 1, the pump-turbine unit 2, and the turbine generator set 6 are arranged in parallel in the same hydropower station. The front end of the pressure steel pipe 5 is connected to the reservoir. The control system 7 is connected to the generator set 1, the pump-turbine unit 2, and the power grid dispatching system.

[0005] Preferably, the power of the generator set 1 and the water pump turbine set 2 are matched with the regulating power of the water turbine generator set 6.

[0006] Preferably, a trash rack 4 is installed at the outlet of the tailwater pipe 3.

[0007] Preferably, the control system 7 is located in the central control room of the hydropower station.

[0008] A method for improving the efficiency of a hydroelectric turbine using pumped storage, employing the aforementioned structure for improving hydroelectric turbine efficiency using pumped storage, includes the following steps:

[0009] When there is excess power in the power grid and the output of the hydropower station needs to be reduced, the control system 7 starts the pumping function of the generator set 1 and the pump turbine set 2. The downstream river water is pumped from the tailrace pipe 3 to the pressure steel pipe 5 by the pump turbine set 2 and then flows into the reservoir. At this time, the actual output of the turbine generator set 6 can be unaffected by the load change in the power grid and can always operate in the high-efficiency operating range.

[0010] When the power grid is insufficient and the output of the hydropower station needs to be increased, the control system 7 starts the power generation function of the generator set 1 and the water pump turbine set 2. The water flows from the reservoir into the pressure steel pipe 5, then flows through the water pump turbine set 2 and makes it rotate, which in turn drives the generator set 1 to generate electricity. At this time, the actual output of the hydro-generator set 6 is not affected by the load change in the power grid and can always operate in the high-efficiency operating range.

[0011] A method for calculating the efficiency improvement of a water turbine using pumped storage, comprising the following steps:

[0012] Assuming that the operating head of both the hydro-generator unit 6 and the pump-turbine unit 2 is h, and the area of ​​their inlets is A, then

[0013] When all the guide vanes of the turbine in hydro-generator unit 6 are open and it is operating at high efficiency, the output p1 is:

[0014]

[0015] In the formula: n—number of hydro-generators; η1—efficiency of the hydro-generator during high-efficiency operation; γ—specific weight of water; μ—inlet flow coefficient; A—inlet area of ​​the hydro-generator; h—operating head of the hydro-generator.

[0016] When the guide vanes of the turbine in hydro-generator unit 6 are open and it is operating at low efficiency, the output p2 is:

[0017]

[0018] In the formula: η2——efficiency of the hydro-generator during inefficient operation; β——opening of the guide vanes when the hydro-turbine is operating inefficiently.

[0019] Because pumping water by turbine unit 2 requires the consumption of some electrical energy, the power consumption p3 is...

[0020]

[0021] In the formula: m—number of pump-turbine units; A—inlet area of ​​pump-turbine unit; η3—pumping efficiency of pump-turbine unit; h—operating head of pump-turbine unit.

[0022] Then, the actual output p1' of the hydro-generator unit 6 when it is operating at high efficiency is...

[0023]

[0024] According to the traditional regulation method, when the load in the power grid decreases significantly, the output of the hydro-generator unit 6 needs to be significantly reduced, and most of the turbine's guide vanes will close. At this time, the efficiency of the hydro-generator unit 6 will decrease significantly, leading to an increase in the water consumption of the hydro-generator unit 6 and affecting the efficiency of the hydropower station. Therefore, as long as the actual output of the hydro-generator unit 6 is not much lower than its rated power, the hydro-generator unit 6 can meet the conditions for efficient operation. From equation (5), it can be seen that the efficiency improvement of the hydro-generator unit 6 compared with the low-efficiency operation is as follows: as η1 / η2 and n continuously increase, p1' / p2 will continuously increase, and the actual efficiency of the turbine will continuously improve.

[0025] The beneficial effects of this invention are:

[0026] (1) By arranging generator sets and pump-turbine sets in the hydropower station, the output of the hydropower station can be flexibly changed with the load in the power grid. The actual output of the turbine sets can be maintained without reducing the actual output of the turbine sets, ensuring that the turbine sets operate in the high-efficiency operating range, thereby improving the efficiency of the turbines, reducing water consumption, and increasing the power generation of the hydropower station.

[0027] (2) It can reduce the impact of the turbine being in adverse operating conditions, allowing it to operate in the high-efficiency range for a longer period of time, which can reduce the number of maintenance operations and improve the reliability and service life of the equipment. It can also reduce the vibration of the turbine unit, which is beneficial to the safety of the hydropower station building.

[0028] (3) This method is simple and reliable. Compared with newly constructed pumped storage power stations, it is easier to implement. It only requires replacing the existing small number of turbine units of the hydropower station with pump turbine units, replacing the generator units with generator motor units, and making simple modifications to the downstream tailrace pipe to realize the functions of pumped storage and power generation. Attached Figure Description

[0029] Figure 1 This is a typical planar schematic diagram of the present invention;

[0030] Figure 2 This is a typical cross-sectional schematic diagram of the present invention;

[0031] Figure 3 This is a schematic diagram of the control system of the present invention.

[0032] The labels in the diagram are as follows: generator set-1, water pump turbine set-2, tailrace pipe-3, trash rack-4, pressure steel pipe-5, turbine generator set-6, control system-7. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of the present invention is not limited to the description.

[0034] Example 1: Figure 1-3As shown, a structure for improving turbine efficiency using pumped storage includes a generator set 1, a pump-turbine unit 2, a tailrace pipe 3, a pressure pipe 5, a turbine-generator set 6, and a control system 7, realizing the pumped storage and power generation functions of a hydropower station. The generator set 1 and the pump-turbine unit 2 are connected by the same main shaft, with the inlet of the pump-turbine unit 2 connected to the end of the pressure pipe 5. The outlet of the pump-turbine unit 2 is connected to the tailrace pipe 3, which is connected to the downstream river channel. The generator set 1, pump-turbine unit 2, and turbine-generator set 6 are arranged side-by-side in the same hydropower station. The front end of the pressure pipe 5 is connected to the reservoir. The control system 7 is connected to the generator set 1, the pump-turbine unit 2, and the power grid dispatching system. The turbine-generator set 6 consists of a turbine and a generator connected by the same main shaft; the turbine drives the generator to generate electricity.

[0035] Furthermore, the power of the generator set 1 and the water pump turbine set 2 are matched with the regulating power of the water turbine generator set 6.

[0036] Furthermore, a trash rack 4 is installed at the outlet of the tailwater pipe 3 to prevent large floating objects from entering and affecting the operation of the generator set 1 and the water pump turbine set 2.

[0037] Furthermore, the control system 7 is located in the central control room of the hydropower station.

[0038] A method for improving the efficiency of a hydroelectric turbine using pumped storage, employing the aforementioned structure for improving hydroelectric turbine efficiency using pumped storage, includes the following steps:

[0039] When there is excess electrical energy in the power grid and the output of the hydropower station needs to be reduced, the control system 7 starts the pumping function of the generator set 1 and the pump-turbine set 2. The downstream river water is pumped by the pump-turbine set 2 through the tailrace pipe 3 to the pressure steel pipe 5, and then flows into the reservoir. The pump-turbine set 2 consumes the excess electrical energy in the power grid, so the actual output of the turbine generator set 6 is not reduced, ensuring that the turbine generator set 6 always operates in the high-efficiency operating range and improving the efficiency of the turbine.

[0040] When the power grid is insufficient and an increase in the hydropower station's output is required, the control system 7 activates the generator-turbine unit 1 and the pump-turbine unit 2. Water flows from the reservoir into the pressure pipe 5, then through the pump-turbine unit 2, causing it to rotate and drive the generator-turbine unit 1 to generate electricity, supplementing the power grid and alleviating the power shortage. This allows for flexible scheduling of the hydropower station. At this time, the actual output of the turbine-generator unit 6 is unaffected by changes in the grid load and can operate continuously in its high-efficiency range. Therefore, the hydropower station's regulation tasks are mainly accomplished through the generator-turbine unit 1 and the pump-turbine unit 2, ensuring that the turbine unit 6 operates at high efficiency, reducing water consumption, and increasing the hydropower station's power generation.

[0041] A method for calculating the efficiency improvement of a water turbine using pumped storage, comprising the following steps:

[0042] Assuming that the operating head of both the hydro-generator unit 6 and the pump-turbine unit 2 is h, and the area of ​​their inlets is A, then

[0043] When all the guide vanes of the turbine in hydro-generator unit 6 are open and it is operating at high efficiency, the output p1 is:

[0044]

[0045] In the formula: n—number of hydro-generators; η1—efficiency of the hydro-generator during high-efficiency operation; γ—specific weight of water; μ—inlet flow coefficient; A—inlet area of ​​the hydro-generator; h—operating head of the hydro-generator.

[0046] When the guide vanes of the turbine in hydro-generator unit 6 are open and it is operating at low efficiency, the output p2 is:

[0047]

[0048] In the formula: η2——efficiency of the hydro-generator during inefficient operation; β——opening of the guide vanes when the hydro-turbine is operating inefficiently.

[0049] Because pumping water by turbine unit 2 requires the consumption of some electrical energy, the power consumption p3 is...

[0050]

[0051] In the formula: m—number of pump-turbine units; A—inlet area of ​​pump-turbine unit; η3—pumping efficiency of pump-turbine unit; h—operating head of pump-turbine unit.

[0052] Then, the actual output p1' of the hydro-generator unit 6 when it is operating at high efficiency is...

[0053]

[0054] According to the traditional regulation method, when the load in the power grid decreases significantly, the output of the hydro-generator unit 6 needs to be significantly reduced, and most of the turbine's guide vanes will close. At this time, the efficiency of the hydro-generator unit 6 will decrease significantly, leading to an increase in the water consumption of the hydro-generator unit 6 and affecting the efficiency of the hydropower station. Therefore, as long as the actual output of the hydro-generator unit 6 is not much lower than its rated power, the hydro-generator unit 6 can meet the conditions for efficient operation. From equation (5), it can be seen that the efficiency improvement of the hydro-generator unit 6 compared with the low-efficiency operation is as follows: as η1 / η2 and n continuously increase, p1' / p2 will continuously increase, and the actual efficiency of the turbine will continuously improve.

[0055] If we take η1 = 0.9, η2 = 0.6, η3 = 0.9, β = 0.5, n = 3, and m = 1, then p1' / p2 = 1.765, and the actual output of the turbine will increase by 76.5%, which is a very significant effect. The more turbines there are, the more pronounced the increase in actual output, indicating that this method is more suitable for hydropower stations with multiple generating units.

[0056] The method of this invention is simple and has a simple structure. It can easily increase the operating power of the water turbine, solve the problem of low water turbine efficiency, significantly improve the efficiency of the water turbine and the power generation of the hydropower station, reduce water consumption, and increase the economic benefits of the hydropower station.

[0057] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for improving the efficiency of a water turbine using pumped storage, characterized in that: The structure includes a generator set (1), a pump-turbine unit (2), a tailrace pipe (3), a pressure steel pipe (5), a turbine generator set (6), and a control system (7). The generator set (1) and the pump-turbine unit (2) are connected by the same main shaft, and the inlet of the pump-turbine unit (2) is connected to the end of the pressure steel pipe (5). The outlet of the pump-turbine unit (2) is connected to the tailrace pipe (3), and the tailrace pipe (3) is connected to the downstream river channel. The generator set (1), the pump-turbine unit (2), and the turbine generator set (6) are arranged in parallel in the same hydropower station. The front end of the pressure steel pipe (5) is connected to the reservoir. The control system (7) is connected to the generator set (1), the pump-turbine unit (2), and the power grid dispatching system, respectively. The method includes the following steps: When there is excess power in the power grid and the output of the hydropower station needs to be reduced, the control system (7) starts the pumping function of the generator set (1) and the pump turbine set (2). The downstream river water is pumped by the pump turbine set (2) through the tailrace pipe (3) to the pressure steel pipe (5) and then flows into the reservoir. At this time, the actual output of the turbine generator set (6) is not affected by the load change in the power grid and always operates in the high-efficiency operating zone. When the power grid is insufficient and the power output of the hydropower station needs to be increased, the control system (7) starts the power generation function of the generator set (1) and the water pump turbine set (2). The water flows from the reservoir into the pressure steel pipe (5), then flows through the water pump turbine set (2) and makes it rotate, and then drives the generator set (1) to generate electricity. At this time, the actual output of the hydro-generator set (6) is not affected by the load change in the power grid and always operates in the high-efficiency operating range.

2. The method for improving turbine efficiency using pumped storage as described in claim 1, characterized in that: The power of the generator set (1) and the water pump turbine set (2) are matched with the regulating power of the water turbine generator set (6).

3. The method for improving turbine efficiency using pumped storage as described in claim 1, characterized in that: A trash rack (4) is installed at the outlet of the tailwater pipe (3).

4. The method for improving turbine efficiency using pumped storage as described in claim 1, characterized in that: The control system (7) is located in the central control room of the hydropower station.

5. A method for calculating the efficiency improvement of a water turbine using pumped storage, characterized in that: The method for improving turbine efficiency using pumped storage as described in claim 1 includes the following steps: Assuming that the operating head of both the hydro-generator unit (6) and the pump-turbine unit (2) is h, and the area of ​​their inlets is A, then When the guide vanes of the turbine in the hydro-generator unit (6) are fully open and it is operating at high efficiency, the output p1 is: （1） Where: n—number of hydro-generators; η1—efficiency of the hydro-generator during high-efficiency operation; γ—specific weight of water; μ—inlet flow coefficient; A—inlet area of ​​the hydro-generator; h—operating head of the hydro-generator; When the guide vanes of the turbine in the hydro-generator unit (6) are open and it is operating at low efficiency, the output p2 is: （2） Where: η2—efficiency of the hydro-generator during inefficient operation; β—opening of the guide vanes during inefficient operation of the hydro-turbine; Since the water pump turbine unit (2) needs to consume some electrical energy to pump water, the power consumption p3 is （3） Where: m—number of pump-turbine units; A—inlet area of ​​pump-turbine unit; η3—pumping efficiency of pump-turbine unit; h—operating head of pump-turbine unit; So, the actual output p1 of the hydro-generator unit (6) when it is operating at high efficiency for （4） （5） From equation (5), it can be seen that the efficiency improvement of the hydro-generator unit (6) compared to its inefficient operation is as follows: as η1 / η2 and n continuously increase, p1 / p2 will continue to increase, and the actual efficiency of the water turbine will continue to improve.

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