Radial flow type pumped storage power station and working method thereof

Abstract

The invention relates to a runoff type pumped storage power station which comprises an upper reservoir, an upper water conveying pipeline, a lower reservoir, a lower water conveying pipeline, a pumping valve, a tail water valve, a tail water pipeline, a pump turbine, a downstream river channel and a plant. The pumped storage power station workshop is built on the downstream side of the lower reservoir; the upper reservoir, the upper water conveying pipeline, the water inlet ball valve, the pump turbine, the tail water valve and the tail water pipeline form a power generation channel; the lower reservoir, the lower water conveying pipeline, the water pumping valve, the pump turbine, the water inlet ball valve, the upper water conveying pipeline and the upper reservoir form a water pumping channel; the runoff volume of the lower reservoir meets the water consumption of pumped storage, and water media for pumped storage and power generation are not circulated. The lower reservoir hydropower station is combined to construct and share the lower reservoir, the water-turbine generator set of the hydropower station is used as a semi-synchronous starting power supply of the water pumping working condition of the pumped storage unit, the pumped storage unit pumps water from the pressurized water source of the lower reservoir, the suction height of the water pump turbine set is reduced, the engineering cost is reduced, and the overall energy efficiency is improved.

Description

Technical Field

[0002] The present invention belongs to the technical field of pumped storage, and particularly relates to a runoff-type pumped storage power station and its working method. Background Art

[0003] A hydropower station is composed of hydraulic structures, a powerhouse, hydro-generator units, a step-up substation, power transmission equipment, etc. The hydro-generator units convert water energy into electrical energy to provide power for the power grid. The hydraulic structures of a hydropower station include a dam, diversion structures, and water discharge structures, etc. The dam is the main structure of the hydropower station, whose function is to block water to raise the water level, store water volume, and concentrate the head of the upstream river section to form a reservoir with a certain head and storage capacity. The hydro-generator units draw water from the reservoir to generate electricity. The diversion structures include intake, trash rack, gate, etc., as well as channels, tunnels, surge chambers, penstocks, etc. that make up the water conveyance structures.

[0004] A pumped storage power station is a regulating power station that uses the electric energy during the low electricity load period to pump water to the upper reservoir and discharges water to the lower reservoir to generate electricity during the high electricity load peak period. The most important tasks of a pumped storage power station are peak shaving, valley filling, and energy storage. The engineering layout of a pumped storage power station mainly includes an upper reservoir, upper intake / outlet, water conveyance system, lower reservoir, lower intake / outlet, powerhouse, and other special buildings, etc. A reversible pump-turbine unit is widely used in pumped storage power stations. Conventional fresh water pumped storage power stations generally need to newly build an upper reservoir and a lower reservoir, or use an existing reservoir as the upper reservoir (lower reservoir) and newly build a lower reservoir (upper reservoir). With the popularization of photovoltaic power generation and wind power, the demand for the most cost-effective pumped storage power stations in the power grid will increase significantly.

[0005] The storage capacity ratio of a pumped storage power station is much smaller than that of a conventional hydropower station. Most of the upper reservoirs of the existing and under-construction pumped storage power stations in China are newly built, with a storage capacity of 5 million - 15 million m 3 . A pumped storage power station usually undertakes daily or weekly regulation tasks, and the water level amplitude of the reservoir is very large. Due to the relatively high comprehensive efficiency at high heads, most pumped storage power stations have relatively high heads; because the cavitation coefficient of the pump-turbine in the pump working condition is relatively large, the pumped storage units require a relatively large submerged depth, so underground powerhouses are most widely used.

[0006] The cycle efficiency of a pumped storage power station refers to the energy conversion efficiency of the pumping and power generation system, that is, the ratio of the power generation amount to the pumping power consumption of the pumped storage power station. This technical indicator reflects the energy losses caused by factors such as the efficiency of the units and transformers, water volume losses in the upper reservoir and water conveyance system, head losses in the water conveyance system, and the increased lift. Usually, the efficiency of a pumped storage power station is about 75%. Summary of the Invention

[0008] The object of the present invention is to provide a radial flow pumped storage power station and its working method, which can improve the operation efficiency of the pumped storage power station and reduce the construction cost of the pumped storage power station.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows: The radial flow pumped storage power station of the present invention is characterized in that it includes an upper reservoir, an upper water conveyance pipeline, a lower reservoir, a lower water conveyance pipeline, a pumping valve, a tail water valve, a tail water pipeline, a pump-turbine, a pumped storage power station powerhouse, and a downstream river channel; the pumped storage power station powerhouse is built on the downstream side of the lower reservoir; the pump-turbine is arranged in the pumped storage power station powerhouse; a series-connected upper water conveyance pipeline and an intake ball valve are provided between the upper reservoir and the volute of the pump-turbine; a series-connected lower water conveyance pipeline and a pumping valve are provided between the lower reservoir and the draft tube cone of the pump-turbine; a series-connected tail water pipeline and a tail water valve are provided between the draft tube cone of the pump-turbine and the downstream river channel; The lower water conveyance pipeline, the tail water pipeline, and the draft tube cone of the pump-turbine form a tee structure controlled by the pumping valve and the tail water valve; The runoff of the lower reservoir meets the water volume for pumped storage; the water for pumped storage is directly discharged into the downstream river channel after power generation and is not recycled.

[0010] Preferably, a hydropower station powerhouse and a hydro-generating set arranged in the hydropower station powerhouse are provided on the downstream side of the lower reservoir, a hydropower station water conveyance pipeline is provided between the lower reservoir and the hydro-generating set, and a hydropower station tail water pipeline is provided between the draft tube cone of the hydro-generating set and the downstream river channel.

[0011] Preferably, the hydro-generating set in the hydropower station powerhouse can be used as a semi-synchronous starting power source for the pumping condition of the pump-turbine in the pumped storage power station powerhouse.

[0012] Preferably, when the water level difference Hjp between the lower reservoir and the downstream river channel is Hjp = Hopt - Hopp + ∑ht + ∑hp, both the pumping and power generation conditions of the pump-turbine operate at the optimal point, where Hopt is the optimal head of the power generation condition of the pump-turbine, Hopp is the optimal lift of the pumping condition of the pump-turbine, ∑ht is the total hydraulic loss of the flow-through part of the power generation condition of the pump-turbine, and ∑hp is the total hydraulic loss of the flow-through part of the pumping condition of the pump-turbine.

[0013] Preferably, when the water level difference Hjp between the lower reservoir and the downstream river channel is Hjp ≥ Hsp - Hst, the suction height of the pump-turbine is selected according to the turbine condition, where Hst is the suction height of the power generation condition of the pump-turbine and Hsp is the suction height of the pumping condition of the pump-turbine.

[0014] The working method of the radial flow pumped-storage power station of the present invention is characterized in that the working process of the pump-turbine of the pumped-storage power station in the pumping condition is as follows: close the tail water valve, open the pumping valve, the tail water draft tube of the pump-turbine communicates with the lower reservoir, and the motor-generator drives the pump-turbine to pump the water from the lower reservoir to the upper reservoir; the working process of the pump-turbine of the pumped-storage power station in the generating condition is as follows: close the pumping valve, open the tail water valve, the tail water draft tube of the pump-turbine communicates with the downstream river channel, start the pump-turbine to drive the motor-generator set to generate electricity, and the water in the upper reservoir flows into the downstream river channel through the pump-turbine.

[0015] The present invention has the following benefits: Firstly, in combination with the construction of the hydropower station, the lower reservoir is shared, thus reducing the project cost; Secondly, the pump-turbine is used to pump the water from the lower reservoir to the upper reservoir for energy storage. The water in the upper reservoir is directly discharged into the downstream river channel after being generated by the pump-turbine generator set. The water of the pumped-storage power station is not recycled, removing the energy conversion process of the water in the lower reservoir being generated by the water turbine generator set and supplied to the pumped-storage unit, improving the overall energy efficiency; furthermore, a power generation plant and a water turbine generator set are arranged on the downstream side of the lower reservoir. After ensuring the water volume required for pumped storage, electricity is directly generated and fed into the grid according to the water inflow of the river channel and the water level of the lower reservoir; and, the water turbine generator set can be used as a semi-synchronous starting power supply for the pumping condition of the pumped-storage unit, effectively simplifying the starting equipment of the pumped-storage unit; In addition, pumping water from the lower reservoir increases the tail water level in the pumping condition, reduces its suction depth, and the power plant can be ground-mounted or semi-underground, greatly reducing the project cost and facilitating operation and management; Moreover, the appropriate water level difference between the lower reservoir and the downstream river channel can make the head in the pumping condition and the water head in the generating condition of the pump-turbine both at the optimal point; and, by selecting a doubly-fed variable-speed pumped-storage unit, the water level difference between the lower reservoir and the downstream river channel can reduce the capacity of the converter. Description of the Drawings Figure 1 It is a schematic diagram of the tail water three-way structure of the pump-turbine of the present invention; Figure 2 It is a schematic diagram of the pumping condition of the pump-turbine of the present invention; Figure 3 It is a schematic diagram of the generating condition of the pump-turbine of the present invention; Figure 4 It is a schematic diagram of the electrical wiring for semi-synchronous starting of the water turbine generator set for the pumping condition of the pump-turbine of the present invention; In the figure: 1 - upper reservoir; 2 - lower reservoir; 3 - downstream river channel; 12 - upper water conveyance pipeline; 13 - inlet ball valve of pump - turbine; 14 - lower water conveyance pipeline; 15 - pumping valve; 16 - tail - water valve; 17 - tail - water pipeline; 18 - pump - turbine; 19 - pumped - storage power station building; 21 - water conveyance pipeline of hydropower station; 22 - hydro - generator set; 23 - tail - water pipeline of hydropower station; 24 - hydropower station building. Specific implementation manners The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0018] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0019] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] This embodiment provides a runoff - type pumped - storage power station, which includes an upper reservoir 1, a lower reservoir 2, a downstream river channel 3, an upper water conveyance pipeline 12, an inlet ball valve 13 of a pump - turbine, a lower water conveyance pipeline 14, a pumping valve 15, a tail - water valve 16, a tail - water pipeline 17, a pump - turbine 18, a pumped - storage power station building 19, a water conveyance pipeline 21 of a hydropower station, a hydro - generator set 22, a tail - water pipeline 23 of a hydropower station, and a hydropower station building 24; the pumped - storage power station building 19 is built on the downstream side of the lower reservoir 2; the pump - turbine 18 is arranged in the pumped - storage power station building 19; a series - connected upper water conveyance pipeline 12 and inlet ball valve 13 are provided between the upper reservoir 1 and the volute of the pump - turbine 18; a series - connected lower water conveyance pipeline 14 and pumping valve 15 are provided between the lower reservoir 2 and the draft tube cone of the pump - turbine 18; a series - connected tail - water pipeline 17 and tail - water valve 16 are provided between the draft tube cone of the pump - turbine 18 and the downstream river channel 3; the lower water conveyance pipeline 14, the tail - water pipeline 17, and the draft tube cone of the pump - turbine 18 form a tee structure controlled by the pumping valve 15 and the tail - water valve 16.

[0021] The runoff of the lower reservoir 2 meets the water consumption for pumped - storage. The water after pumped - storage is directly discharged into the downstream river channel after power generation and is not recycled.

[0022] A hydropower plant building 24 is provided on the downstream side of the lower reservoir 2. The power generation water flow path of the hydropower station is as follows: lower reservoir 2 - hydropower station water conveyance pipeline 21 - water turbine generator set 22 - hydropower station tailrace pipeline 23 - downstream river channel 3.

[0023] The semi-synchronous starting power supply for the pumping condition of the pumped-storage unit is supplied by the water turbine generator set 22 in the hydropower plant building 24.

[0024] The working process of the pump-turbine of the pumped-storage power station in the pumping condition is as follows: close the tailrace valve 16, open the pumping valve 15. The draft tube of the pump-turbine 18 communicates with the lower reservoir 2. The pump-turbine 18 is driven by the motor generator to pump the water from the lower reservoir 2 to the upper reservoir 1, as Figure 2 shown.

[0025] The working process of the pump-turbine of the pumped-storage power station in the power generation condition is as follows: close the pumping valve 15, open the tailrace valve 16. The draft tube of the pump-turbine 18 communicates with the downstream river channel 3. Start the pump-turbine 18 to drive the motor generator set to generate electricity. The water in the upper reservoir 1 flows through the pump-turbine into the downstream river channel 3, as Figure 3 shown.

[0026] When the water level difference Hjp between the lower reservoir and the downstream river channel = Hopt - Hopp + ∑ht + ∑hp, both the pumping and power generation conditions of the pump-turbine operate at the optimal point. Hopt is the optimal head of the pump-turbine in the power generation condition, Hopp is the optimal lift of the pump-turbine in the pumping condition, ∑ht is the total hydraulic loss of the flow-through part of the pump-turbine in the power generation condition, and ∑hp is the total hydraulic loss of the flow-through part of the pump-turbine in the pumping condition.

[0027] When the water level difference Hjp between the lower reservoir and the downstream river channel ≥ Hsp - Hst, the suction height of the pump-turbine is selected according to the water turbine condition. Hst is the suction height of the pump-turbine in the power generation condition, and Hsp is the suction height of the pump-turbine in the pumping condition.

[0028] Specific examples are as Figures 1 to 4 shown.

[0029] Example: A hydropower station in the middle reaches of the Min River, with an installed capacity of 1.4 million kW, a guaranteed output of 0.26 million kW, and an average annual power generation of 4.95 billion kW•h. It is connected to the power grid through 3 500 kV and 6 220 kV transmission lines. The drainage area controlled by the dam site of the hydropower station is 52,438 km 2 , and the average annual flow at the dam site is 1,728 m 3 / s, with an annual runoff volume of 54.5 billion m 3 , the measured maximum flow is 30,200 m 3 / s, and the minimum flow is 196 m 3 / s, the total storage capacity of the lower reservoir 2 is 2.34 billion m 3 , and the regulating storage capacity is 0.7 billion m 3 . The normal storage level of the lower reservoir 2 is 65 m, and the flood season operation limit level is 61 m. When the full-load discharge of the hydropower station units is 3934 m 3 / s, the water level of the downstream river channel 3 below the dam is 11.3 m. The hydropower station powerhouse 24 is located behind the dam on the left side of the riverbed. The main powerhouse is about 301 m long, 36 m wide, and 62.3 m high. It is equipped with 7 axial-flow hydro-generator units 22 with a single-unit capacity of 200,000 kW. The maximum head of the water turbine is 58 m, the minimum head is 30 m, and the design head is 45.3 m.

[0030] An upper reservoir 1 is built on the left bank slope of the existing hydropower station (the reservoir of the existing hydropower station is named the lower reservoir 2). The normal storage level of the upper reservoir 1 is 505 m, and the dead storage level is 481 m. A semi-underground pumped-storage power station powerhouse 19 is built on the left bank downstream side of the existing hydropower station dam. 4 sets of pump-turbines 18 are installed in the pumped-storage power station powerhouse 19. An upper water conveyance pipeline 12 and an inlet ball valve 13 are provided between the upper reservoir 1 and the spiral case of the pump-turbine 18; A lower water conveyance pipeline 14 and a pumping valve 15 are provided between the lower reservoir 2 and the draft tube cone of the pump-turbine 18; A tailwater pipeline 17 and a tailwater valve 16 are provided between the draft tube cone of the pump-turbine 18 and the downstream river channel 3; The lower water conveyance pipeline 14, the tailwater pipeline 17 and the draft tube cone of the pump-turbine 18 form a tee structure controlled by the pumping valve 15 and the tailwater valve 16.

[0031] When the full-load discharge of the 7 hydro-generator units and 4 pumped-storage units of the hydropower station is 4300 m 3 / s, the tailwater level of the downstream river channel 3 corresponding to the dam is 11.5 m; When all the hydropower station units are stopped and the full-load discharge of the 4 pumped-storage units is 360 m 3 / s, the tailwater level of the downstream river channel 3 corresponding to the dam is 7.1 m.

[0032] The pumped-storage power station and the hydropower station share 3 500 kV and 6 220 kV transmission lines to access the power grid; The semi-synchronous starting power supply for the pumping operation of the pumped-storage units is supplied by the hydro-generator units 22 in the hydropower station powerhouse 24.

[0033] The working process of the pump-turbine 18 of the pumped-storage power station in the pumping mode is as follows: In the 1GM shutdown state, the tailrace valve 16 is closed and the pumping valve 15 is opened, and the draft tube of the pump-turbine 18 communicates with the lower reservoir 2; In the 1G shutdown state, the disconnect switch 6113 is disconnected, and the disconnect switches 9110, 6115, and 6111 are closed; The hydrogenerator 1G is started. When the speed rises to about 80% of the rated speed, excitation is applied to the hydrogenerator 1G, and about 60 - 70% of the rated voltage is generated in the stator of the hydrogenerator 1G; The 910 circuit breaker is closed, and the voltage of the hydrogenerator 1G is applied to the stator of the motor-generator 1GM connected to the pump-turbine. The motor-generator 1GM starts and begins to increase its speed. When the speeds of the two machines are close, excitation is applied to the motor-generator 1GM, and then the motor-generator 1GM is pulled into synchronization; The speed and excitation of the hydrogenerator 1G are adjusted to drive the motor-generator to be synchronized and connected to the grid; The 910 circuit breaker is disconnected, and the disconnect switches 9110 and 6115 are disconnected; The motor-generator 1GM drives the pump-turbine 18 to pump water from the lower reservoir 2 to the upper reservoir 1.

[0034] The working process of the pump-turbine of the pumped-storage power station in the power generation mode is as follows: The pumping valve 15 is closed, the tailrace valve 16 is opened, the draft tube of the pump-turbine 18 communicates with the downstream river channel 3, the pump-turbine 18 is started to drive the motor-generator set to generate electricity, and the water in the upper reservoir 1 flows through the pump-turbine into the downstream river channel 3.

[0035] For the pump-turbine in the mode of pumping water from the lower reservoir 2, its maximum head is 465m and its suction height is about -9m. For the pump-turbine in the power generation mode, its maximum head is 498m and its suction height is about -25m. For the pump-turbine of this pumped-storage power station pumping water from the lower reservoir 2, the suction height is taken as about -25m in the power generation mode, and a semi-underground power house is selected.

[0036] Assuming that the rated head of 486m in the power generation mode of the pump-turbine is the head at the optimal point, then the head of the optimal point of the pump mode at the same speed is about 80% of the head at the optimal point in the power generation mode, about 389m. For the pump-turbine in the mode of pumping water from the lower reservoir 2, its maximum head is 465m, which is 76m higher than the optimal head of 389m; If the pump-turbine is in the mode of pumping water from the downstream river channel 3, its maximum head is 520m, which is 131m higher than the optimal head of 389m.

[0037] Compared with the conventional pumped-storage power station, this scheme has the following benefits: This invention has the following benefits: Firstly, in combination with the construction of the hydropower station, the lower reservoir is shared, thus reducing the project cost; Secondly, the pumped-storage turbine pumps water from the lower reservoir to the upper reservoir for energy storage, which belongs to pumping with pressurized water source. After the water in the upper reservoir is generated by the pumped-storage turbine generator set, it is directly discharged into the downstream river channel without recycling, eliminating the two energy conversion processes of the water in the lower reservoir being generated by the hydro-generator set and then supplied to the pumped-storage unit for pumping, thus improving the overall energy efficiency. Calculated based on the comprehensive efficiency of the hydro-generator being 90%, the average water level difference between the lower reservoir and the downstream river channel being 50 m, the average pumping head of the pumped-storage turbine from the lower reservoir being 465 m, the average pumping head of the pumped-storage turbine from the downstream being 515 m, and the comprehensive efficiency of the pumped-storage turbine in the pumping condition being 90%, the comprehensive efficiency of the pumped-storage turbine pumping from the pressurized water source in the lower reservoir is 1.8% higher than that of pumping from the downstream river channel; the change in the tail water level is 20 - 30 meters less than that of a general pumped-storage power station, and the efficiency of both the pumping and generating conditions is improved; the electricity generated during the low-load period of the hydropower station in the wet season is locally supplied to the pumped-storage unit, eliminating the transmission loss of the power grid; Furthermore, a power generation plant and hydro-generator sets are installed on the downstream side of the lower reservoir. After ensuring the water volume required for pumped storage, power is directly generated and fed into the grid according to the water inflow of the river channel and the water level of the lower reservoir; in addition, the hydro-generator sets can be used as a semi-synchronous starting power source for the pumping condition of the pumped-storage unit, effectively simplifying the starting equipment of the pumped-storage unit; In addition, pumping water from the lower reservoir increases the tail water level in the pumping condition and reduces its suction depth. The power plant can be ground-mounted or semi-underground, greatly reducing the project cost and facilitating operation and management; Moreover, an appropriate water level difference between the lower reservoir and the downstream river channel can make the pumping head of the pumped-storage turbine in the pumping condition and the water head in the generating condition both at the optimal point; and by selecting a doubly-fed variable-speed pumped-storage unit, the water level difference between the lower reservoir and the downstream river channel can reduce the capacity of the converter.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: modifications can still be made to the specific implementation manners of the present invention or equivalent replacements can be made to some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A radial flow pumped storage power station, characterized in that: It includes an upper reservoir (1), an upper water conveyance pipeline (12), a lower reservoir (2), a lower water conveyance pipeline (14), a pumping valve (15), a tail water valve (16), a tail water pipeline (17), a pump-turbine (18), a pumped-storage power station building (19), and a downstream river channel (3); the pumped-storage power station building (19) is built on the downstream side of the lower reservoir (2); the pump-turbine (18) is arranged in the pumped-storage power station building (19); a series-connected upper water conveyance pipeline (12) and an intake ball valve (13) are provided between the upper reservoir (1) and the volute of the pump-turbine (18); a series-connected lower water conveyance pipeline (14) and a pumping valve (15) are provided between the lower reservoir (2) and the draft tube cone of the pump-turbine (18); a series-connected tail water pipeline (17) and a tail water valve (16) are provided between the draft tube cone of the pump-turbine (18) and the downstream river channel (3); the lower water conveyance pipeline (14), the tail water pipeline (17), and the draft tube cone of the pump-turbine (18) form a tee structure controlled by the pumping valve (15) and the tail water valve (16). The runoff of the lower reservoir (2) meets the water consumption for pumped storage, and the water after pumped storage power generation is directly discharged into the downstream river channel without recycling.

2. The radial-flow pumped storage power station according to claim 1, wherein: A hydropower station building (24) and a hydro-generating unit (22) arranged in the hydropower station building (24) are provided on the downstream side of the lower reservoir (2), a hydropower station water conveyance pipeline (21) is provided between the lower reservoir (2) and the hydro-generating unit (22), and a hydropower station tail water pipeline (23) is provided between the draft tube cone of the hydro-generating unit (22) and the downstream river channel (3).

3. A radial flow pumped storage power station according to claim 1, characterized in that: The hydro-generating unit (22) in the hydropower station building (24) serves as a semi-synchronous starting power source for the pumping operation of the pump-turbine (18) in the pumped-storage power station building (19).

4. A radial flow pumped storage power station according to claim 1, wherein: When the water level difference Hjp between the lower reservoir (2) and the downstream river channel (3) = Hopt - Hopp + ∑ht + ∑hp, both the pumping and power generation operations of the pump-turbine (18) operate at the optimal points, where Hopt is the optimal head of the power generation operation of the pump-turbine (18), Hopp is the optimal lift of the pumping operation of the pump-turbine (18), ∑ht is the total hydraulic loss of the flow-through part of the power generation operation of the pump-turbine (18), and ∑hp is the total hydraulic loss of the flow-through part of the pumping operation of the pump-turbine.

5. A radial flow pumped storage power station according to claim 4, characterized in that: When the water level difference Hjp between the lower reservoir (2) and the downstream river channel (3) ≥ Hsp - Hst, the suction height of the pump-turbine (18) is selected according to the turbine operation condition, Hst is the suction height of the power generation operation of the pump-turbine, and Hsp is the suction height of the pumping operation of the pump-turbine.

6. A working method of a radial flow pumped storage power station as described in any one of claims 1-5, characterized in that, The working process of the pump-turbine (18) of the pumped-storage power station in the pumping mode is as follows: close the tailwater valve (16), open the pumping valve (15), the draft tube of the pump-turbine (18) communicates with the lower reservoir (2), and the pump-turbine (18) is driven by the motor-generator to pump the water from the lower reservoir (2) to the upper reservoir (1); the working process of the pump-turbine (18) of the pumped-storage power station in the generating mode is as follows: close the pumping valve (15), open the tailwater valve (16), the draft tube of the pump-turbine (18) communicates with the downstream river channel (3), start the pump-turbine (18) to drive the motor-generator set to generate electricity, and the water in the upper reservoir (1) flows into the downstream river channel (3) through the pump-turbine.

7. A radial flow pumped storage power station, characterized in that: There is a hydropower station in the middle reaches of a certain river, named the Lower Reservoir (2), with an installed capacity of 1.4 million kW, a guaranteed output of 260,000 kW, and an average annual power generation of 4.95 billion kW•h. It is connected to the power grid through 3 circuits of 500 kV and 6 circuits of 220 kV transmission lines; the catchment area controlled by the dam site of the hydropower station is 52,438 km 2 , and the average annual flow at the dam site is 1,728 m 3 / s, with an annual runoff volume of 54.5 billion m 3 . The measured maximum flow is 30,200 m 3 / s, and the minimum flow is 196 m 3 / s. The total storage capacity of the Lower Reservoir (2) is 2.34 billion m 3 , and the regulating storage capacity is 700 million m 3 ; the normal storage level of the Lower Reservoir (2) is 65 m, and the flood season operation limit level is 61 m. When the full-load flow of the hydropower station units is 3,934 m 3 / s, the water level of the downstream river channel (3) downstream of the dam is 11.3 m; the hydropower station powerhouse (24) is located behind the dam on the left side of the riverbed. The main powerhouse is about 301 m long, 36 m wide, and 62.3 m high, and is equipped with 7 axial-flow hydro-generator units (22) with a single unit capacity of 200,000 kW. The maximum head of the water turbine is 58 m, the minimum head is 30 m, and the design head is 45.3 m; An upper reservoir (1) is built on the left bank slope of the lower reservoir (2). The normal storage level of the upper reservoir (1) is 505 m, and the dead level is 481 m. A semi-underground pumped-storage power station building (19) is built on the left bank downstream side of the dam of the lower reservoir (2). Four sets of pump-turbine inlet ball valves (13) and pump-turbines (18) are installed in the pumped-storage power station building (19). An upper water conveyance pipeline (12) and an inlet ball valve (13) are provided between the upper reservoir (1) and the spiral case of the pump-turbine (18); a lower water conveyance pipeline (14) and a pumping valve (15) are provided between the lower reservoir (2) and the draft tube of the pump-turbine (18); a tailwater pipeline (17) and a tailwater valve (16) are provided between the draft tube of the pump-turbine (18) and the downstream river channel (3); the lower water conveyance pipeline (14), the tailwater pipeline (17) and the draft tube of the pump-turbine (18) form a tee structure controlled by the pumping valve (15) and the tailwater valve (16). The pumped-storage power station shares 3 circuits of 500 kV and 6 circuits of 220 kV transmission lines with the hydropower station to access the power grid; the semi-synchronous starting power supply for the pumping mode of the pumped-storage unit is supplied by the water turbine generator set (22) in the hydropower station building (24).

8. A working method of the radial flow pumped storage power station as described in claim 7, characterized in that, The working process of the pump-turbine of a pumped-storage power station in the pumping mode is as follows: In the 1GM shutdown state, the tailrace valve (16) is closed and the pumping valve (15) is opened, and the draft tube of the pump-turbine (18) communicates with the lower reservoir (2); In the 1G shutdown state, the disconnecting switch 6113 is disconnected, and the disconnecting switches 9110, 6115, and 6111 are closed; The hydrogenerator 1G is started. When the speed rises to about 80% of the rated speed, excitation is applied to the hydrogenerator 1G, and about 60 - 70% of the rated voltage is generated in the stator of the hydrogenerator 1G; The 910 circuit breaker is closed, and the voltage of the hydrogenerator 1G is applied to the stator of the motor-generator 1GM connected to the pump-turbine. The motor-generator 1GM starts and begins to increase speed. When the speeds of the two machines are close, excitation is applied to the motor-generator 1GM, and then the motor-generator 1GM is pulled into synchronization; The speed and excitation of the hydrogenerator 1G are adjusted to drive the motor-generator to be synchronized and connected to the grid; The 910 circuit breaker is disconnected, and the disconnecting switches 9110 and 6115 are disconnected; The motor-generator 1GM drives the pump-turbine 18 to pump water from the lower reservoir (2) to the upper reservoir (1). The working process of the pump-turbine of a pumped-storage power station in the power generation mode is as follows: The pumping valve (15) is closed, the tailrace valve (16) is opened, the draft tube of the pump-turbine (18) communicates with the downstream river channel (3), and the pump-turbine (18) is started to drive the motor-generator set to generate electricity. The water in the upper reservoir (1) flows through the pump-turbine into the downstream river channel (3). For the pump-turbine pumping water from the lower reservoir (2), its maximum head is 465m and its suction height is about -9m; For the pump-turbine in the power generation mode, its maximum head is 498m and its suction height is about -25m; For the pump-turbine of the pumped-storage power station pumping water from the lower reservoir (2), the suction height is taken as -25m in the power generation mode, and a semi-underground power house is selected; When the rated head of 486m in the power generation mode of the pump-turbine is the optimal head, the head of the optimal point of the pump mode at the same speed is about 80% of the optimal head in the power generation mode, about 389m; For the pump-turbine pumping water from the lower reservoir (2), its maximum head is 465m, which is 76m higher than the optimal head of 389m; For the pump-turbine pumping water from the downstream river channel (3), its maximum head is 520m, which is 131m higher than the optimal head of 389m.

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