Structure and method for improving efficiency of water turbine in pumped storage mode and improving efficiency calculation method

Abstract

The invention relates to a structure and method for improving the efficiency of a water turbine in a pumped storage mode and a lifting efficiency calculation method, and belongs to the technical field of water conservancy projects. When electric energy in a power grid is excessive, water can be pumped from a downstream river channel to an upstream reservoir by starting the water pumping function of the water pump turbine set, redundant electric energy in the power grid is consumed, and therefore actual output of the water turbine set is not reduced. The hydraulic turbine set always operates in a high-efficiency operation area, and the efficiency of the hydraulic turbine is improved. When the output of the hydropower station is required to be increased due to insufficient electric energy in the power grid, the power grid can be supplemented with electric energy by starting the power generation function of the pump turbine set, the situation of insufficient electric power in the power grid is relieved, and flexible dispatching of the hydropower station is achieved. The operation efficiency is improved without reducing the output of the hydraulic turbine set, the water consumption is reduced, and the power generation efficiency of the hydropower station is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of water conservancy engineering, and specifically relates to a structure and method for improving the efficiency of a water turbine by utilizing a pumped storage method, and a method for calculating the improved efficiency. Background Art

[0002] Turbine efficiency is one of the key factors affecting the economic benefits and sustainable development of hydropower stations. At present, through optimized design, regular maintenance and improved operation management, the efficiency of turbines can be significantly improved, and the overall power generation capacity and economic benefits of hydropower stations can be improved. However, each turbine design has a specific rated head and flow range. Only within this range, the efficiency of the turbine is usually high, and the efficiency of some large and medium-sized turbines can reach more than 95%. However, if the working head of the turbine is far away from the rated head and flow, the efficiency of the turbine will be greatly reduced, even to only about 30%. Even for new turbines, under rated head, when the turbine output is only 50% of the rated power, its efficiency will be reduced to about 80%; if the head is lower than the rated head, its efficiency will continue to decline. In fact, in the middle and late stages of the dry season, and in the flood season, the water level in front of the reservoir is relatively low for flood control requirements, which will cause the actual power of the turbine to be lower than the rated power. Therefore, in some time, the operating efficiency of the turbine unit of the hydropower station is relatively low, which affects the power generation of the hydropower station. At the same time, as the use time goes by, the turbine will also face the problem of aging, which will cause its efficiency to continue to decrease and affect the power generation capacity of the hydropower station. In addition, the low operating efficiency of the turbine will also cause the unit to vibrate too much, worsen the operating conditions of the turbine, further reduce the efficiency of the turbine, and also affect the safety of the pier. Therefore, how to improve the efficiency of the turbine and increase the power generation of the hydropower station is one of the key measures to alleviate my country's energy shortage. At present, the design level of the turbine is already very high, and the efficiency of the turbine can be guaranteed to be above 90%. It is difficult to significantly improve the efficiency of the turbine by relying on the optimized design and regular maintenance of the turbine. Therefore, some new methods and means are urgently needed to improve the efficiency of the turbine. Summary of the invention

[0003] In view of the problem that the actual power of existing turbines is far lower than the rated power, which will cause their efficiency to drop significantly, the present invention proposes a structure, method and efficiency improvement calculation method for improving the efficiency of turbines by using pumped storage. This method selects 1 to 2 turbines from the existing turbine units of the hydropower station and transforms them into pump turbine units, and transforms their generator units into generator motor units to realize the pumped storage and power generation functions of the hydropower station. When the hydropower station requires to reduce the output, the pumping function of the generator motor unit can be started to consume the excess electric energy in the power grid, so as not to reduce the actual output of the turbine, ensure that the turbine unit is always running near the rated power, and improve the efficiency of the turbine. When the hydropower station requires to increase the output, the power generation function of the generator motor unit can be started to supplement the power grid and alleviate the power shortage in the grid.

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

[0005] Preferably, the power of the generator motor set 1 and the water pump turbine set 2 matches the regulated 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 arranged in a central control room of the hydropower station.

[0008] A method for improving the efficiency of a water turbine by using a pumped storage method, using the structure for improving the efficiency of a water turbine by using a pumped storage method, comprises 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 motor unit 1 and the water pump turbine unit 2, and the downstream river water is pumped by the water pump turbine unit 2 to the pressure steel pipe 5 through the tailwater pipe 3, and then flows into the reservoir. At this time, the actual output of the hydro-generator unit 6 is not affected by the load change in the power grid and can always operate in the high-efficiency operation area;

[0010] When the power grid is short of energy 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 pump-turbine set 2. Water flows from the reservoir into the pressure steel pipe 5, then flows through the pump-turbine set 2 and rotates it, 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 changes in the power grid and can always operate in the high-efficiency operating area.

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

[0012] Assuming that the working water head of turbine generator set 6 and pump turbine set 2 is h, and the area of ​​their water inlet is A, then

[0013] When the guide vanes of the turbine in the hydro-generator set 6 are all opened and in high-efficiency operation, the output p1 is

[0014]

[0015] In the formula: n is the number of turbine generators; η1 is the efficiency of the turbine generator when it is running at high efficiency; γ is the density of water; μ is the flow coefficient of the water inlet orifice; A is the water inlet area of ​​the turbine generator; h is the working water head of the turbine generator.

[0016] When the guide vanes of the turbine in the hydro-generator set 6 are partially opened and in low-efficiency operation, the output p2 is

[0017]

[0018] Where: η2 is the efficiency of the turbine generator when it is running at a low efficiency; β is the opening of the guide vane when the turbine is running at a low efficiency.

[0019] Since the pump-turbine unit 2 consumes some electrical energy to pump water, the power consumption p3 is

[0020]

[0021] In the formula: m is the number of pump-turbines; A is the water inlet area of ​​the pump-turbine; η3 is the pumping efficiency of the pump-turbine; h is the working water head of the pump-turbine.

[0022] Then the actual output p1' of the hydro-generator set 6 when it is running at high efficiency is

[0023]

[0024] According to the traditional regulation method, when the load in the power grid is greatly reduced, the output of the hydro-generator set 6 needs to be greatly reduced, and the guide vanes of the turbine will be mostly closed. At this time, the efficiency of the hydro-generator set 6 will be greatly reduced, resulting in an increase in the water consumption of the hydro-generator set 6, which affects the efficiency of the hydropower station. Therefore, as long as the actual output of the hydro-generator set 6 is not much lower than its rated power, the hydro-generator set 6 can meet the conditions for efficient operation. From formula (5), it can be seen that the efficiency improvement of the hydro-generator set 6 relative to the inefficient operation, as η1 / η2 and n continue to increase, p1' / p2 will continue to increase, and then the actual efficiency of the turbine will continue to improve.

[0025] The beneficial effects of the present 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 without reducing the actual output of the turbine set, ensuring that the turbine set operates in the high-efficiency operating area, thereby improving the efficiency of the turbine, reducing water consumption, and increasing the power generation of the hydropower station.

[0027] (2) It can reduce the impact of the turbine being in an unfavorable working condition, keep it in the high-efficiency operating area for a long time, reduce the number of maintenance times, 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 plant.

[0028] (3) This method is simple and reliable, and is easier to implement than a newly constructed pumped-storage power station. It only requires replacing a small number of existing turbine units in the hydropower station with pump-turbine units, replacing the generator units with generator motor units, and making simple modifications to the downstream tailwater pipe to achieve the functions of pumped storage and power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a typical plan view of the present invention;

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

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

[0032] The numbers in the figure are: generator set-1, pump turbine set-2, tailwater pipe-3, trash rack-4, pressure steel pipe-5, turbine generator set-6, control system-7. DETAILED DESCRIPTION

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

[0034] Example 1: Figure 1-3As shown, a structure for improving the efficiency of a water turbine by pumped storage includes a generator motor set 1, a pump turbine set 2, a tailwater pipe 3, a pressure steel pipe 5, a water turbine generator set 6 and a control system 7, so as to realize the pumped storage and power generation functions of a hydropower station. The generator motor set 1 and the pump turbine set 2 are connected by the same main shaft, and the water inlet of the pump turbine set 2 is connected to the end of the pressure steel pipe 5, the water outlet of the pump turbine set 2 is connected to the tailwater pipe 3, and the tailwater pipe 3 is connected to the downstream river channel. The generator motor set 1, the pump turbine set 2 and the water 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, and the control system 7 is respectively connected to the generator motor set 1, the pump turbine set 2 and the power grid dispatching system. The water turbine generator set 6 is composed of a water turbine and a generator, which are connected by the same main shaft, and the water turbine drives the generator to generate electricity.

[0035] Furthermore, the power of the generator motor unit 1 and the water pump turbine unit 2 matches the regulated power of the water turbine generator unit 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 motor unit 1 and the water pump turbine unit 2 .

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

[0038] A method for improving the efficiency of a water turbine by using a pumped storage method, using the structure for improving the efficiency of a water turbine by using a pumped storage method, comprises the following steps:

[0039] When there is excess electric 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 motor unit 1 and the pump-turbine unit 2. The downstream river water is pumped by the pump-turbine unit 2 to the pressure steel pipe 5 through the tailwater pipe 3 and then flows into the reservoir. Water is pumped from the downstream river to the upstream reservoir. The pump-turbine unit 2 will consume the excess electric energy in the power grid, so that the actual output of the turbine generator unit 6 will not be reduced, ensuring that the turbine generator unit 6 is always operating in the high-efficiency operating area, thereby improving the efficiency of the turbine.

[0040] When the power grid is short of electricity and the output of the hydropower station is required to be increased, the control system 7 starts the power generation function of the generator motor unit 1 and the pump turbine unit 2, and the water flows from the reservoir into the pressure steel pipe 5, then flows through the pump turbine unit 2 and rotates it, and then drives the generator motor unit 1 to generate electricity, replenishing electricity to the power grid, alleviating the power shortage in the power grid, and realizing flexible scheduling of the hydropower station. At this time, the actual output of the turbine generator unit 6 can be unaffected by the load changes in the power grid, and can always operate in the high-efficiency operation area. Therefore, the regulation task of the hydropower station is mainly completed by the generator motor unit 1 and the pump turbine unit 2, ensuring that the turbine unit 6 is always operating in a high-efficiency state, reducing water consumption, and increasing the power generation of the hydropower station.

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

[0042] Assuming that the working water head of turbine generator set 6 and pump turbine set 2 is h, and the area of ​​their water inlet is A, then

[0043] When the guide vanes of the turbine in the hydro-generator set 6 are all opened and in high-efficiency operation, the output p1 is

[0044]

[0045] In the formula: n is the number of turbine generators; η1 is the efficiency of the turbine generator when it is running at high efficiency; γ is the density of water; μ is the flow coefficient of the water inlet orifice; A is the water inlet area of ​​the turbine generator; h is the working water head of the turbine generator.

[0046] When the guide vanes of the turbine in the hydro-generator set 6 are partially opened and in low-efficiency operation, the output p2 is

[0047]

[0048] Where: η2 is the efficiency of the turbine generator when it is running at a low efficiency; β is the opening of the guide vane when the turbine is running at a low efficiency.

[0049] Since the pump-turbine unit 2 consumes some electrical energy to pump water, the power consumption p3 is

[0050]

[0051] In the formula: m is the number of pump-turbines; A is the water inlet area of ​​the pump-turbine; η3 is the pumping efficiency of the pump-turbine; h is the working water head of the pump-turbine.

[0052] Then the actual output p1' of the hydro-generator set 6 when it is running at high efficiency is

[0053]

[0054] According to the traditional regulation method, when the load in the power grid is greatly reduced, the output of the hydro-generator set 6 needs to be greatly reduced, and the guide vanes of the turbine will be mostly closed. At this time, the efficiency of the hydro-generator set 6 will be greatly reduced, resulting in an increase in the water consumption of the hydro-generator set 6, which affects the efficiency of the hydropower station. Therefore, as long as the actual output of the hydro-generator set 6 is not much lower than its rated power, the hydro-generator set 6 can meet the conditions for efficient operation. From formula (5), it can be seen that the efficiency improvement of the hydro-generator set 6 relative to the inefficient operation, as η1 / η2 and n continue to increase, p1' / p2 will continue to increase, and then the actual efficiency of the turbine will continue to improve.

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

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

[0057] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A structure for improving the efficiency of a water turbine by using a pumped storage method, characterized in that: The invention comprises a generator motor set (1), a pump turbine set (2), a tailwater pipe (3), a pressure steel pipe (5), a hydro-turbine generator set (6) and a control system (7). The generator motor set (1) and the pump turbine set (2) are connected by a same main shaft, the water inlet of the pump turbine set (2) is connected to the end of the pressure steel pipe (5), the water outlet of the pump turbine set (2) is connected to the tailwater pipe (3), the tailwater pipe (3) is connected to a downstream river channel, the generator motor set (1), the pump turbine set (2) and the hydro-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 a reservoir, and the control system (7) is respectively connected to the generator motor set (1), the pump turbine set (2) and a power grid dispatching system.

2. A structure for improving the efficiency of a water turbine by using a pumped storage method according to claim 1, characterized in that: The power of the generator motor set (1) and the water pump turbine set (2) matches the regulated power of the water turbine generator set (6).

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

4. The structure for improving the efficiency of a water turbine by using a pumped storage method according to claim 1, characterized in that: The control system (7) is arranged in the central control room of the hydropower station.

5. A method for improving the efficiency of a water turbine by using a pumped storage method, characterized in that: The structure for improving the efficiency of a water turbine by using a pumped storage method as claimed in any one of claims 1 to 4 comprises the following steps: When there is excess electric 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 motor unit (1) and the water pump turbine unit (2), and the downstream river water is pumped by the water pump turbine unit (2) to the pressure steel pipe (5) through the tailwater pipe (3), and then flows into the reservoir. At this time, the actual output of the water turbine generator unit (6) is not affected by the load change in the power grid and is always operating in the high-efficiency operation area; When the power in 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 motor set (1) and the water pump turbine set (2), and water flows from the reservoir into the pressure steel pipe (5), then flows through the water pump turbine set (2) and rotates it, and then drives the generator motor set (1) to generate electricity. At this time, the actual output of the water turbine generator set (6) is not affected by the load change in the power grid and is always operating in the high-efficiency operation area.

6. A method for calculating the efficiency of a hydraulic turbine using a pumped storage system, characterized in that: The method for improving the efficiency of a water turbine by using a pumped storage method as claimed in claim 5 comprises the following steps: Assuming that the working water head of the turbine generator set (6) and the pump turbine set (2) is h, and the area of ​​their water inlet is A, then When the guide vanes of the turbine in the hydro-generator set (6) are all opened and the output p1 is in high efficiency operation, In the formula: n is the number of turbine generators; η1 is the efficiency of the turbine generator when it is running at high efficiency; γ is the density of water; μ is the flow coefficient of the water inlet orifice; A is the water inlet area of ​​the turbine generator; h is the working water head of the turbine generator; When the guide vanes of the turbine in the hydro-generator set (6) are partially opened and in low-efficiency operation, the output p2 is Where: η2 is the efficiency of the turbine generator when it is running at low efficiency; β is the opening of the guide vane when the turbine is running at low efficiency; Since the water pump turbine unit (2) consumes some electric energy to pump water, the power consumption p3 is Where: m - the number of pump turbines; A - the water inlet area of ​​the pump turbine; η3 - the pumping efficiency of the pump turbine; h - the working water head of the pump turbine; Then the actual output p1' of the hydro-generator set (6) when it is in high-efficiency operation is From formula (5), we can know the efficiency improvement of the hydro-generator set (6) compared with the low-efficiency operation. As η1 / η2 and n continue to increase, p1' / p2 will continue to increase, and the actual efficiency of the turbine will continue to improve.

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