Multi-stage series diversion power station

Abstract

The present invention discloses a water diversion power station, in particular, a multi-stage series water diversion power station, which belongs to the technical field of design and construction of water conservancy and hydropower engineering structures. A multi-stage series water diversion power station with strong regulation capability and low dam construction requirements is provided. The multi-stage series water diversion power station includes at least two power stations, and the power stations connected in sequence are connected to the external water diversion system through the top power station. The multi-stage series water diversion power station also includes a ground water level composite regulation structure, and the adjacent two power stations are respectively connected through the ground water level composite regulation structure so that the power generation water level can be adjusted; during operation, the tail water and water intake levels between the two adjacent power stations are timely adjusted by the ground water level composite regulation structure.

Description

Technical Field

[0001] The present invention relates to a water diversion type power station, in particular to a multi-stage series water diversion type power station, and belongs to the technical field of design and construction of water conservancy and hydropower engineering structures. Background Art

[0002] For diversion-type hydropower plants, if the water drop is too large, the design and manufacturing limitations of the turbines and penstocks necessitate a multi-stage series arrangement. To minimize the impact of operations between upstream and downstream power plants and to ensure adequate response time in the event of an emergency, a regulating pond is typically installed between two adjacent diversion-type hydropower plants, connecting the tailwater outlet of the upstream power plant with the water inlet of the downstream power plant, thereby improving the operational stability and safety of the entire system.

[0003] During stable operation, the flow rate of tailwater from the upstream power station entering the regulating pond equals the reference flow rate at the downstream power station's inlet, and the regulating pond water level remains unchanged. During unstable or emergency conditions, the flow rate of tailwater from the upstream power station entering the regulating pond no longer equals the reference flow rate at the downstream power station's inlet. When the inflow from the upstream power station exceeds the reference flow rate at the downstream power station, the regulating pond water level rises; otherwise, the water level drops. The regulating pond design must meet the upper and lower water level requirements for both operating conditions.

[0004] Ground regulating ponds are typically formed by damming natural river channels. To maintain upper and lower water level requirements, the reservoir capacity must be sufficiently large, and thus the dam height must be high enough. When foundation conditions prohibit the construction of a high dam, slope excavation is excessive, or earthquake intensity is too high, the dam height must be controlled while still meeting the aforementioned basic functional requirements of the regulating pond. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a multi-stage series water diversion power station with strong regulation capability and low dam construction requirements.

[0006] The technical solution adopted to solve the above technical problems is: a multi-stage series water diversion power station, including at least two power stations, the power stations connected in sequence are connected to the external water diversion system through the top power station, the multi-stage series water diversion power station also includes a ground water level composite regulation structure, and the adjacent power stations are respectively connected through the ground water level composite regulation structure so that the power generation water level can be adjusted; during operation, the tail water and water intake levels between the two adjacent power stations are timely adjusted through the ground water level composite regulation structure.

[0007] Furthermore, the ground water level composite regulation structure includes at least one set of separation and regulation mechanisms and a water reservoir between two adjacent power stations. A water reservoir is respectively divided into an upper regulation pool and a lower regulation pool that are interconnected by a set of separation and regulation mechanisms. The tail water outlet of the upper power station is connected to the upper regulation pool, and the water inlet of the adjacent lower power station is connected to the corresponding lower regulation pool.

[0008] The preferred embodiment of the above scheme is that each water reservoir located between two adjacent power stations is surrounded by corresponding slopes, riverbeds and retaining dams of the adjacent next-level power station, and each water reservoir is separated into a connectable upper regulating pool and a lower regulating pool along the water flow direction by a corresponding separation and regulation mechanism.

[0009] Furthermore, the emergency storage capacity of the upper regulating pool is controlled by V1=Qt1, where Q is the reference flow of normal power generation of a single-stage power station in the series cascade power station, and t1 is the emergency response time of the accident.

[0010] The emergency storage capacity of the lower regulating pond is controlled according to V2=Qt2, where t2 is the time during which the upper power station continues to generate electricity when the generating units of the lower power station are shut down in an emergency, and V2 is the emergency water storage capacity of the lower regulating pond operating at the normal operating water level for t2 hours.

[0011] The preferred embodiment of the above scheme is that the separation and regulation mechanism includes a water retaining dam and a water supply connection system, the water reservoir is divided into an upper regulating tank and a lower regulating tank by the water retaining dam, and the upper regulating tank and the lower regulating tank are interconnected in a closable manner through the water supply connection system.

[0012] Furthermore, the height of the water retaining dam is obtained based on the reservoir capacity calculated by V1=Qt1, and the height of the water retaining dams of power stations at all levels except the first-level generating station is obtained based on the reservoir capacity calculated by V2=Qt2.

[0013] A preferred embodiment of the above solution is that the water supply connection system is a water supply steel pipe with a normally open stop valve.

[0014] Furthermore, the water supply steel pipe is an exposed pipe laid on the bottom of the water retaining dividing dam and the lower regulating tank, or is an underground culvert buried under the water retaining dividing dam to connect the upper regulating tank and the lower regulating tank.

[0015] The preferred embodiment of the above scheme is that the water supply connection system includes a water supply culvert and a self-closing gate. The water supply culvert is conveniently arranged at the bottom of the water retaining dam along the water flow, and the self-closing gate is arranged on the water supply culvert inside the water retaining dam.

[0016] Furthermore, the self-closing gate includes a pivot column, a working gate leaf and an auxiliary gate leaf. An installation cavity and a closed gate water inlet channel are provided on the water transfer culvert. The water inlet of the closed gate water inlet channel is connected with the lower regulating tank, and the water outlet of the closed gate water inlet channel is connected with the installation cavity. The working gate leaf and the auxiliary gate leaf are respectively arranged in the installation cavity through the pivot column. The elevation of the water inlet of the closed gate water inlet channel is determined according to the storage capacity calculated by V2=Qt2. The working gate leaf and the auxiliary gate leaf can be rotatably arranged in the installation cavity of the water transfer culvert through the pivot column with the cooperation of the closed gate water input into the closed gate water inlet channel.

[0017] The beneficial effects of the present invention are as follows: the technical solution provided by the present application is based on the existing series-connected power stations, combined with the characteristics of the sequential connection of the power stations at each level, and the connection of the top power station with the external water diversion system, and by adding a ground water level composite regulating structure to form a new multi-stage series water diversion power station, and then the adjacent two-stage power stations are respectively connected through the ground water level composite regulating structure so that the power generation water level can be adjusted; in this way, during operation, the tail water and water intake levels between the two adjacent power stations can be conveniently adjusted in time through the ground water level composite regulating structure. Since the multi-stage series water diversion power station of the present application is based on the existing structure, and only the ground water level composite regulating structure is added on this basis to realize the connection of the tail water and water intake between the two adjacent power stations and the water level regulation, it solves the technical problem in the prior art of simply setting a regulating pool for water level regulation, which causes the regulation to fail due to extreme conditions. Furthermore, since the improvement is based on the existing regulating pond, it not only greatly improves the water level regulation capacity, but also has relatively low dam construction requirements. There is no need to build a high dam, which avoids excessive excavation of the slope and excessively high requirements for earthquake intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the planar layout structure of a multi-stage series diversion type power station according to the present invention;

[0019] Figure 2 A longitudinal sectional view of a single-stage regulation involved in a multi-stage series diversion hydropower station of the present invention;

[0020] Figure 3 A longitudinal sectional view of the composite regulation involved in the multi-stage series diversion hydropower station of the present invention;

[0021] Figure 4 、 Figure 5 A longitudinal cross-sectional view of the multi-stage series diversion power station of the present invention for compound adjustment of different water levels;

[0022] Figure 6 This is a longitudinal cross-sectional view of an exposed water pipe involved in a multi-stage series water diversion power station of the present invention;

[0023] Figure 7 A longitudinal cross-sectional view of an underground culvert pipe used as a water delivery steel pipe in a multi-stage series water diversion power station according to the present invention;

[0024] Figure 8 、 Figure 9 It is a structural schematic diagram of the water transmission connection system involved in the multi-stage series water diversion power station of the present invention.

[0025] Marked in the figure are: ground water level composite regulating structure 1, separation regulating mechanism 2, water storage reservoir 3, upper regulating tank 4, lower regulating tank 5, tailwater outlet 6, water inlet 7, slope 8, riverbed 9, retaining dam 10, water retaining separation dam 11, water transmission connection system 12, water transmission culvert 13, self-closing gate 14, pivot column 15, working gate leaf 16, auxiliary gate leaf 17, installation cavity 18, closed gate water inlet channel 19. DETAILED DESCRIPTION

[0026] like Figures 1 to 9 The present invention provides a multi-stage series water diversion power station with strong regulation capabilities and low dam construction requirements. The multi-stage series water diversion power station includes at least two power stations, each of which is connected in sequence to an external water diversion system via the top power station. The multi-stage series water diversion power station also includes a ground water level composite regulation structure 1, and the power generation water level between adjacent power stations is adjustable through the ground water level composite regulation structure 1. During operation, the tailwater and water intake levels between the two adjacent power stations are timely adjusted by the ground water level composite regulation structure 1. The technical solution provided by this application is based on the existing series power stations. In combination with the characteristics of the power stations being connected in sequence and the top power station being connected to the external water diversion system, a new multi-stage series water diversion power station is formed by adding a ground water level composite regulation structure. Then, the power generation water level between the two adjacent power stations is adjustable through the ground water level composite regulation structure. In this way, during operation, the tailwater and water intake levels between the two adjacent power stations can be conveniently adjusted in a timely manner through the ground water level composite regulation structure. Because the multi-stage series diversion power station of this application is based on an existing structure and only adds a composite ground water level regulation structure to connect the tailwater and intake water between two adjacent power stations and regulate the water level, it not only solves the technical problem of the existing technology that the simple use of regulating ponds for water level regulation can lead to extreme conditions and regulation failure. Furthermore, because it is an improvement based on existing regulating ponds, it not only greatly improves the water level regulation capacity, but also has relatively low dam construction requirements, eliminating the need for high dam construction, avoiding excessive slope excavation and excessively high seismic intensity requirements.

[0027] Correspondingly, in combination with the structural characteristics that each water reservoir 3 located between two adjacent power stations is surrounded by corresponding slopes 8, riverbeds 9 and the retaining dam 10 of the adjacent next-level power station, the present application sets the ground water level composite regulation structure 1 to include at least one group of separation and regulation mechanisms 2 and a water reservoir 3 between two adjacent power stations. A water reservoir 3 is respectively divided into an upper regulating pool 4 and a lower regulating pool 5 that can be interconnected by a group of separation and regulation mechanisms 2. The tail water outlet 6 of the upper-level power station is connected to the upper regulating pool 4, and the water inlet 7 of the adjacent next-level power station is connected to the corresponding lower regulating pool 5. Each water reservoir 3 is separated into a connectable upper regulating pool 4 and a lower regulating pool 5 along the water flow direction by the corresponding separation and regulation mechanism 2. At this time, the emergency storage capacity of the upper regulating tank 4 is controlled according to V1=Qt1, where Q is the reference flow of normal power generation of a single-stage power station in a series cascade power station, t1 is the emergency response time of the accident, and the emergency storage capacity of the lower regulating tank 5 is controlled according to V2=Qt2, t2 is the time during which the upper-stage power station continues to generate electricity when the unit of the lower-stage power station is shut down in an emergency, and V2 is the emergency water storage capacity of the lower regulating tank when it operates at the normal operating water level for t2 hours. More specifically, the present application sets the separation and regulation mechanism 2 as a structure including a water retaining dam 11 and a water transmission connection system 12. The water storage reservoir 3 is divided into the upper regulating tank 4 and the lower regulating tank 5 by the water retaining dam 11. The upper regulating tank 4 and the lower regulating tank 5 are connected to each other in a closable manner through the water transmission connection system 12. Specifically, the height of the water retaining dam 11 is determined based on the storage capacity calculated by V1=Qt1, and the height of the water retaining dam 10 of the power stations at all levels except the first-stage generator station is determined based on the storage capacity calculated by V2=Qt2.

[0028] In this case, the water connection system 12 can be a steel pipe with a normally open shutoff valve, or it can include a water culvert 13 and a self-closing gate 14. When a steel pipe is used, depending on the structural characteristics of the reservoir, the water pipe can be an exposed pipe laid on the bottom of the water retaining dam 11 and the lower regulating tank 5, or an underground culvert buried below the water retaining dam 11 to connect the upper regulating tank 4 and the lower regulating tank 5. When the water connection system 12 uses a water culvert 13 and a self-closing gate 14, the water culvert 13 of the water connection system 12 is conveniently located at the bottom of the water retaining dam 11 along the water flow, and the self-closing gate 14 is installed on the water culvert 13 within the water retaining dam 11. In order to automatically open and close the water culvert according to the water level of the lower regulating tank 5, the self-closing gate 14 includes a pivot column 15, a working gate leaf 16 and an auxiliary gate leaf 17. An installation cavity 18 and a closed-door water inlet channel 19 are provided on the water culvert 13. The water inlet of the closed-door water inlet channel 19 is connected to the lower regulating tank 5, and the water outlet of the closed-door water inlet channel 19 is connected to the installation cavity 18. The working gate leaf 16 and the auxiliary gate leaf 17 are respectively arranged in the installation cavity 18 through the pivot column 15. The elevation of the water inlet of the closed-door water inlet channel 19 is determined according to the storage capacity calculated by V2=Qt2. The working gate leaf 16 and the auxiliary gate leaf 17 can be rotatably arranged in the installation cavity of the water culvert 13 through the pivot column 15 with the cooperation of the closed-door water input from the closed-door water inlet channel 19.

[0029] In summary, the above technical solution provided by this application also has the following advantages:

[0030] The graded ground regulating pond form reduces the dam height while meeting the regulating pond function.

[0031] The technical solution of this application is further described below through specific embodiments:

[0032] Example 1

[0033] 1. Basic boundary conditions

[0034] As mentioned above, the basic functions of regulating ponds are: (1) to reduce the impact of fluctuations caused by differences in output between upstream and downstream power stations during operation; and (2) to store or supply water in emergency situations. Generally, the storage capacity and water level fluctuations required in the latter are much greater than those in the former, and are considered control conditions.

[0035] Assume that the reference flow rate for normal power generation in a series cascade system is Q, and the emergency response time is t. If the generator units of the upper power station are shut down in an emergency, while the lower power station continues generating power for t, the regulating pond must provide an emergency water supply capacity of V1 = Qt below the normal operating water level. If the generator units of the lower power station are shut down in an emergency, while the upper power station continues generating power for t, the regulating pond must provide an emergency water storage capacity of V2 = Qt above the normal operating water level. When using a single-stage regulating pond, the total regulating reservoir capacity must satisfy V = V1 + V2 = 2Qt, corresponding to a dam height of H.

[0036] 2. Classification of regulating ponds

[0037] The regulating pond is divided into two levels: the upper pond and the lower pond, based on the emergency water storage capacity V1 and the emergency water supply capacity V2. Retaining dams are built on each of the upper and lower ponds, and the upper dam is connected to the bottom outlet to ensure hydraulic connection between the two regulating ponds under normal operating conditions.

[0038] During normal operation, the upper pool in the regulating pond is at a low water level and the lower pool is at a high water level. The upper pool and the lower pool are connected through the bottom hole. The water level of the upper pool is higher than that of the lower pool. The height difference depends on factors such as the normal power generation flow rate, the size of the bottom hole, the flow rate requirements in the pool, etc., and is determined according to the actual situation of the project.

[0039] When the upper power station is shut down in an emergency, the flow rate into the pool from the tailwater outlet of the upper power station drops to 0, but the lower power station continues to generate electricity normally, and the reference flow remains unchanged at Q. The water level in the lower pool begins to drop and the water level in the upper pool drops synchronously through the connecting bottom hole. After time t, the lower power station completes the emergency shutdown, and the water level in the lower pool drops to the lower limit level and no longer changes.

[0040] When the lower power station undergoes an emergency shutdown, the outflow rate from the lower power station's inlet drops to zero. However, the upper power station continues to generate power, maintaining the reference flow rate Q. The upper pool water level begins to rise, and the connecting bottom outlet gate closes simultaneously. This rise in the upper pool water level does not cause the lower pool water level to rise and overflow. After time t, the upper power station completes its emergency shutdown, and the upper pool water level rises to the upper limit and remains stationary.

[0041] 3. Other forms of connecting bottom holes

[0042] In addition to the above-mentioned method of establishing a hydraulic connection between the upper and lower pools by connecting the dam body to the bottom hole, the following two methods can also be used to adapt to different topographic and geological conditions: (1) underground culverts; (2) surface pipes.

[0043] Underground culvert: If the opening of the dam body is too large or the cross-section of the dam body is too small to make a hole, an underground culvert can be used. The culvert can pass through the lower part of the dam foundation or around the dam shoulder.

[0044] Ground exposed pipe: If the topographic and geological conditions restrict the upper and lower pools to be arranged at a long distance, they can be connected by ground exposed pipe.

[0045] 4. Control gate of connecting hole / hole

[0046] The control gate of the connecting hole / hole is a critical component. In the event of an emergency shutdown of the downstream power station, the control gate must be closed promptly to ensure that the tailwater flow from the upstream power station is retained in the upper pool. Considering the importance of prompt gate closure in an emergency, otherwise the lower pool may overflow, this invention also provides a mechanically-based automatic gate closing design.

[0047] When the lower power station is shut down urgently, the water level in the lower pool rises. After the water level rises slightly (not exceeding the elevation of the lower pool dam top), it enters the dam body from downstream through the automatic door inlet and triggers the automatic door to close.

[0048] The design principle of gate automatic control is shown in Figure 9 During normal operation, water flows from the upper tank through the bottom hole into the lower tank. The flow direction is shown in the attached diagram. Figure 9 As shown in the middle arrow, since there is no water in the auxiliary gate leaf chamber, the working gate leaf is pushed to a position close to the side wall of the connecting bottom hole by the action of water thrust, and the connecting bottom hole is in an open state. When the lower power station is shut down urgently, the water level in the lower tank rises and enters the auxiliary gate leaf chamber through the automatic door inlet. The width and height of the auxiliary gate leaf are both larger than the working gate leaf. The torque of the water thrust will be greater than the torque of the working gate leaf, and the auxiliary gate leaf is pushed to the side wall of the bottom hole, and the working gate leaf is subsequently closed. Subsequently, the water level in the lower tank stops rising and the water level in the upper tank begins to rise. After a period of time, due to the rising water level in the upper tank, the water thrust torque of the working gate leaf is greater than the auxiliary gate leaf, and the working door is pushed open again, and the auxiliary gate leaf rotates accordingly. At this time, on the one hand, the water level in the auxiliary gate leaf chamber rises, increasing the water thrust. On the other hand, the water level in the lower tank rises, and water flows into the auxiliary gate leaf chamber again. These two factors increase the thrust of the auxiliary gate leaf again, prompting the working gate leaf to close, forming an automatic feedback balance system.

Claims

1. A multi-stage series water diversion power station, comprising at least two power stations, wherein the power stations connected in sequence are connected to an external water diversion system via the top power station, and characterized in that: The multi-stage series water diversion power station further comprises a ground water level composite regulating structure (1), and two adjacent power stations are respectively connected via the ground water level composite regulating structure (1) so that the power generation water level can be adjusted; during operation, the tail water and water intake levels between the two adjacent power stations are timely regulated by the ground water level composite regulating structure (1). The ground water level composite regulating structure (1) comprises at least one set of separation regulating mechanisms (2) and a water reservoir (3) between two adjacent power stations. One water reservoir (3) is respectively divided into an upper regulating pool (4) and a lower regulating pool (5) that are interconnected by the set of separation regulating mechanisms (2). The tailwater outlet (6) of the upper power station is connected to the upper regulating pool (4), and the water inlet (7) of the adjacent lower power station is connected to the corresponding lower regulating pool (5). The emergency storage capacity of the upper regulating pool (4) is controlled by V1=Qt1, where Q is the reference flow of normal power generation of a single-stage power station in the series cascade power station, t1 is the emergency response time of the accident, The emergency storage capacity of the lower regulating pond (5) is controlled by V2=Qt2, where t2 is the time during which the upper power station continues to generate electricity when the generating units of the lower power station are shut down in an emergency, and V2 is the emergency storage capacity of the lower regulating pond when it operates at the normal operating water level for t2 hours. The separation and regulation mechanism (2) includes a water retaining dam (11) and a water transmission connection system (12). The water reservoir (3) is separated into an upper regulating pool (4) and a lower regulating pool (5) by the water retaining dam (11). The upper regulating pool (4) and the lower regulating pool (5) are interconnected in a closable manner by the water transmission connection system (12). The height of the water retaining dam (11) is obtained based on the reservoir capacity calculated by V1=Qt1, and the height of the water retaining dam (10) of each power station except the first power station is obtained based on the reservoir capacity calculated by V2=Qt2.

2. The multi-stage series diversion hydropower station according to claim 1, characterized in that: Each water storage reservoir (3) located between two adjacent power stations is enclosed by corresponding side slopes (8), riverbeds (9) and the retaining dam (10) of the adjacent next-level power station. Each water storage reservoir (3) is separated into a connectable upper regulating pool (4) and a lower regulating pool (5) along the water flow direction by a corresponding separation and regulation mechanism (2).

3. The multi-stage series diversion hydropower station according to claim 1 or 2, characterized in that: The water supply connection system (12) is a water supply steel pipe with a normally open stop valve.

4. The multi-stage series diversion type power station according to claim 3, characterized in that: The water delivery steel pipe is an exposed pipe laid on the bottom of the water retaining dam (11) and the lower regulating pool (5), or is an underground culvert buried below the water retaining dam (11) and connecting the upper regulating pool (4) and the lower regulating pool (5).

5. The multi-stage series diversion hydropower station according to claim 1, characterized in that: The water supply connection system (12) includes a water supply culvert (13) and a self-closing gate (14). The water supply culvert (13) is conveniently arranged at the bottom of the water retaining dam (11) along the water flow, and the self-closing gate (14) is arranged on the water supply culvert (13) inside the water retaining dam (11).

6. The multi-stage series diversion type power station according to claim 5, characterized in that: The self-closing gate (14) includes a pivot column (15), a working gate leaf (16) and an auxiliary gate leaf (17). An installation cavity (18) and a closed gate water inlet channel (19) are provided on the water delivery culvert (13). The water inlet of the closed gate water inlet channel (19) is communicated with the lower regulating tank (5), and the water outlet of the closed gate water inlet channel (19) is communicated with the installation cavity (18). The working gate leaf (16) and the auxiliary gate leaf (17) are respectively arranged in the installation cavity (18) through the pivot column (15). The elevation of the water inlet of the closed gate water inlet channel (19) is determined according to the storage capacity calculated by V2=Qt2. The working gate leaf (16) and the auxiliary gate leaf (17) can be rotatably arranged in the installation cavity of the water delivery culvert (13) through the pivot column (15) in cooperation with the closed gate water input from the closed gate water inlet channel (19).

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