A fish gathering system

Abstract

The present invention provides a fish gathering system, which has a water inlet, a water outlet, and a water flow channel, wherein a blocking member for blocking fish is provided on the water flow channel; a first water flow outlet is opened on the blocking member; the water flow inlet is provided at the tailwater tunnel outlet, or the water flow inlet is provided at a position in the tailwater channel close to the tailwater tunnel outlet; a fish accommodating space connected to the water flow channel is formed on one side of the water flow channel; the water flow outlet forms a first fish inlet, and a fish flow channel is formed between the first fish inlet and the fish accommodating space; the fish flow channel is located on the downstream side of the blocking member; the fish gathering system also includes a drainage structure extending from the water flow inlet to the downstream of the water flow outlet; the fish accommodating space and the drainage structure are respectively located on both sides of the water flow channel; from the position where the water flow outlet is formed by the drainage structure to the end of the drainage structure located on the downstream side, the distance between the drainage structure and the fish accommodating space in the width direction of the tailwater channel gradually increases.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering, and in particular to a fish collecting system for a hydropower station. Background Art

[0002] It's well known that while hydropower stations provide benefits such as flood control, power generation, and shipping, they also have significant impacts on the ecological environment. Dams, in particular, can block fish from migrating upstream in search of spawning grounds. The construction of fish aggregating facilities is one effective measure to mitigate the impact of hydropower projects on fish. For hydropower stations with heads exceeding 100 meters, fish aggregating measures such as fish hoists or fish aggregating systems are often employed, taking into account the site conditions and the specific layout of the hub. A fish aggregating and transporting system, a variation of a fish hoist, typically consists of a fish aggregating vessel and a fish transporting vessel connected front and back.

[0003] The key to a successful fish aggregating system design is water flow conditions, and good water flow conditions are crucial for attracting fish. A fish aggregating system inlet generally uses a water flow that is attractive to fish. However, the flow rate should be kept low, as it will exceed the speed of the aggregating fish and prevent them from entering. Currently, most fish aggregating facilities utilize pump station water replenishment systems to generate a fish-attracting flow to meet the flow requirements of the fish inlet and channel. This replenishment water typically comes from upstream reservoirs or pump stations. This system is expensive to construct and operate, making it less cost-effective.

[0004] The patent application with application number CN201910133528.9 and titled "A fish collecting box and fish collecting method for collecting fish using tailwater" discloses a method of directly using a fish collecting box to collect fish. The tailwater from power generation enters the fish collecting box to form a fish-attracting water flow, and the fish's tendency to flow is used to collect fish. No additional water is required, saving project operating costs.

[0005] However, since the fish collecting box is placed in the tailwater pipe or tailwater tunnel of the power plant, the following shortcomings still exist: ① The fish collecting box is placed in the tailwater pipe or tailwater tunnel of the power plant, and the fish attracting flow cannot be well controlled. When the unit is fully powered, the flow velocity at the tailwater tunnel outlet is generally 4m / s to 5m / s, while the best flow velocity for attracting fish is generally 1m / s to 2m / s. There is a problem that the flow velocity of the fish collecting channel is too large, and it is impossible to dynamically adjust the flow velocity for attracting fish at different water depths; ② The flow velocity at the fish collecting box is placed in the tailwater pipe or tailwater tunnel of the power plant. ③ In the tunnel, the difference between the downstream flow field and the tailwater flow field is small, making it difficult for fish to sense the difference in the flow field and find the fish entrance, which affects the fish attracting effect; ③ When the power station units operate in different modes, the flow velocity in the tailwater tunnel varies greatly, making it very difficult for fish to find the fish entrance, and the fish attracting effect varies greatly; ④ Fish collecting boxes are difficult to collect fish at different water depths, and the range of fish collection is limited; ⑤ When fish collecting boxes are placed in the tailwater pipe or tailwater tunnel of the powerhouse, the water blocking effect is obvious, and the head loss is large, which will cause the downstream water level to rise and affect the power generation efficiency. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a fish collecting system to address at least one of the above-mentioned problems existing in the existing fish collecting system in which the fish collecting box is placed in the tailwater pipe or tailwater tunnel of a powerhouse.

[0007] To solve the above technical problems, the present invention adopts a technical solution: a fish-collecting system, comprising a water inlet, a water outlet, and a water flow channel connected between the water inlet and the water outlet; a blocking member for blocking fish is provided on the water flow channel, and a first water flow outlet is formed on the blocking member; the water flow inlet is provided at the tailrace tunnel outlet so that a portion of the water flow channel is located in the tailrace tunnel, or the water flow inlet is provided in the tailrace channel near the tailrace tunnel outlet;

[0008] A fish accommodating space connected to the water flow channel is formed on one side of the water flow channel; the water flow outlet forms a first fish inlet, and a fish flow channel is formed between the first fish inlet and the fish accommodating space; the fish flow channel is located on the downstream side of the blocking member; the fish collecting system also includes a drainage structure extending from the water flow inlet to the downstream of the water flow outlet; the fish accommodating space and the drainage structure are respectively located on both sides of the water flow channel; from the position of the drainage structure where the water flow outlet is formed to the end of the drainage structure located on the downstream side, the distance between the drainage structure and the fish accommodating space in the width direction of the tailwater channel gradually increases.

[0009] In the above technical solution, the drainage structure is a drainage wall, and the fish collecting system includes a fish collecting device, which extends in the length direction of the tailwater tunnel. A groove is formed on the side of the fish collecting device facing the water flow channel, and the groove forms the fish accommodating space.

[0010] In the above technical solution, the drainage structure is a drainage wall, which includes a first section of the drainage wall arranged at the water inlet; from the top view of the fish collecting system, from the end of the first section of the drainage wall close to the water inlet to the other end away from the water inlet, the distance between the first section of the drainage wall and the fish accommodation space in the width direction of the tailwater channel gradually increases.

[0011] In the above technical solution, the drainage wall includes a first section of the drainage wall, a second section of the drainage wall, and a third section of the drainage wall, which are connected in sequence; the first section of the drainage wall and the third section of the drainage wall are respectively located on the upstream side and downstream side of the second section of the drainage wall; the second section of the drainage wall extends in the length direction of the tailwater tunnel; as viewed from the top direction of the fish gathering system, the distance between the third section of the drainage wall and the fish accommodation space in the width direction of the tailwater channel gradually increases from the end of the third section of the drainage wall close to the water inlet to the other end away from the water inlet; wherein, the connection between the second section of the drainage wall and the third section of the drainage wall is flush with the water outlet, or the connection between the second section of the drainage wall and the third section of the drainage wall is located on the upstream side of the water outlet.

[0012] In the above technical solution, the diversion structure is equipped with a gate structure for adjusting the width of the water inlet; the fish aggregating system is arranged in the tailrace, the water inlet is arranged toward the tailrace tunnel outlet, the fish aggregating device is arranged near one tailrace sidewall, the water flow channel and the one tailrace sidewall are respectively located on both sides of the fish aggregating device, and the water inlet is formed between the gate structure and the downstream end of the tailrace tunnel;

[0013] Alternatively, the following structure is adopted: the diversion structure is equipped with a gate structure for adjusting the width of the water inlet; at least part of the diversion structure and the gate structure extend into the tailwater tunnel, and the water inlet is formed between the gate structure and the side wall of the tailwater tunnel.

[0014] In one structural form of the above technical solution, the fish holding space is provided with a fish collecting box, the upper end of which is open, and the fish collecting system further includes a lifting device for adjusting the height of the fish collecting box; when the fish collecting box is at its lowest height, the height of the fish flow channel between the water outlet and the blocking member is not lower than the height of the top of the fish collecting box;

[0015] In another embodiment of the above technical solution, the fish collecting device is further connected to a baffle; the baffle has a first state and a second state. When the baffle is in the first state, the fish holding space is connected to the water flow channel; when the baffle is in the second state, the baffle separates the fish holding space from the water flow channel. Alternatively, the fish collecting box and the baffle may be provided simultaneously.

[0016] In the above technical solution, the fish gathering system includes a bell-mouth structure; the opening size of the first end of the bell-mouth structure is larger than the opening size of the second end of the bell-mouth structure; the first end opening of the bell-mouth structure forms the first fish entrance, and the second end opening of the bell-mouth structure forms the second fish entrance; the first fish entrance is connected to the fish accommodating space through the second fish entrance; the first fish entrance is located on the downstream side of the second fish entrance.

[0017] In the above technical solution, a mounting piece connected to the bell-mouth structure is provided on the water flow channel; the second end opening of the bell-mouth structure is located at the position where the bell-mouth structure is connected to the mounting piece; the part of the mounting piece located outside the second end opening is used to block fish and form a second water flow outlet; a third water flow outlet is formed on the side wall of the bell-mouth structure.

[0018] In the above technical solution, the width and height of the second fish entrance are 2 to 3 times the length of the largest fish collecting object; the width of the first fish entrance is 3 to 4 times the width of the second fish entrance, and the height of the first fish entrance is 3 to 4 times the height of the second fish entrance.

[0019] In the above technical solution, the drainage structure is equipped with M gate structures for adjusting the width of the water flow inlet and M×N second fish inlets; the M gate structures are arranged sequentially in the height direction to form an M-layer structure, and the gate structure control units corresponding to the respective gate structures are independently arranged; the respective second fish inlets form an overall structure having M layers and N columns; M ≥ 2, N ≥ 1; the second fish inlet located on the mth layer of the overall structure is located at the same height as the mth gate structure, 1 ≤ m ≤ M; the second fish inlets located on the same layer of the overall structure are arranged sequentially in the width direction of the tailrace channel;

[0020] The width of the position corresponding to the mth layer of the gate structure in the water inlet is: e_m=(k_m×N×V_m×D×H×W1×(ku×((W2×H2) / (W1×H1))-ku+1)) / Q;

[0021] Where: k_m is the velocity variation coefficient corresponding to the height of the second fish entrance on the mth layer; V_m is the optimal fish-attracting velocity corresponding to the height of the second fish entrance on the mth layer; D is the width of the tailwater tunnel; H is the water depth at the tailwater tunnel outlet; Q is the tailwater flow rate; W1 is the width of the second fish entrance, H1 is the height of the second fish entrance, W2 is the width of the first fish entrance, H2 is the height of the first fish entrance, and ku is the porosity of the barrier.

[0022] When the height of the first fish entrance of the mth layer is not higher than the tailwater tunnel outlet elevation, the value range of k_m is [1, 1.2]. When the height of the first fish entrance of the mth layer is higher than the tailwater tunnel outlet elevation, the value range of k_m is [1.2, 1.5].

[0023] The fish gathering system provided by the present invention has the following advantages:

[0024] (1) The drainage structure of the present invention can effectively reduce the drainage flow of tail water, so that a better fish-attracting flow rate can be achieved at the water outlet serving as the first fish inlet, making it easier to attract fish and improving the fish gathering efficiency;

[0025] (2) The drainage structure of the present invention can keep the main flow of tail water away from the first fish inlet, thereby generating a significant flow velocity gradient between the first fish inlet and the surrounding flow field, thereby increasing the fish attracting effect;

[0026] (3) The multi-layer gate structure of the present invention can dynamically adjust the tailwater flow rate of each layer. Under different power generation flow rates of the power station, the fish attracting flow rate can be controlled by adjusting the water inlet width, and fish can be gathered at different time periods;

[0027] (4) The present invention can arrange multiple first fish entrances in layers, and the fish-attracting flow rate of the multiple first fish entrances can be dynamically adjusted according to the distribution of fish in the water layer, so that the fish-attracting flow field is more targeted, thereby achieving intelligent fish-attracting;

[0028] (5) The present invention can minimize the impact on the tailwater level while ensuring the flow rate of fish attracting, avoid the accumulation of tailwater, and thus increase the power generation efficiency of the power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 1 is a schematic top view of the fish collecting system, tailrace tunnel, and tailrace channel according to Example 1 of the present invention;

[0031] Figure 2 yes Figure 1 Schematic diagram of the local three-dimensional structure;

[0032] Figure 3 Schematic diagram of the three-dimensional structure of two different fish gathering systems and corresponding tailrace tunnels and tailrace channels according to Example 1 of the present invention;

[0033] Figure 4 yes Figure 1 A schematic front view of the middle blocking member;

[0034] Figure 5 yes Figure 1 Schematic diagram of the three-dimensional structure of the middle bell mouth structure;

[0035] Figure 6 yes Figure 1 A schematic front view of the mounting part;

[0036] Figure 7 is a horizontal cross-section (perpendicular to the height direction) flow velocity cloud diagram obtained when the fish aggregating system of Example 1 of the present invention is applied;

[0037] Figure 8 is a flow velocity cloud diagram of a cross section (perpendicular to the length direction of the tailrace tunnel) viewed from the water outlet to the water inlet when the fish aggregating system of Example 1 of the present invention is applied;

[0038] Figure 9 1 is a schematic top view of a fish collecting system, a tailrace tunnel, and a tailrace channel according to a second embodiment of the present invention;

[0039] Figure 10 is a partial top view of the fish aggregating system when the baffle of Example 3 of the present invention is in the first state;

[0040] Figure 11 is a partial top view of the fish aggregating system when the baffle of Example 3 of the present invention is in the second state;

[0041] Figure 12 is a front view schematic diagram of a blocking member according to embodiment 4 of the present invention;

[0042] The meanings of the numbers in the figure are as follows: 1, first section of diversion wall; 2, second section of diversion wall; 3, third section of diversion wall; 4, control platform; 5, trumpet structure; 51, first fish inlet; 52, second fish inlet; 5A, first guide structure; 5B, second guide structure; 6, door structure; 61, water inlet; 7, fish collecting device; 71, baffle; 72, first guide groove; 73, second guide groove; 91, blocking member; 91A, first connecting rod; 9 2. Mounting part; 92A, second connecting rod; 11. Fish holding space; 12. Fish collecting box; 100, tailrace tunnel; 101, tailrace tunnel outlet; 102, tailrace tunnel side wall; 200, tailrace channel; 201, tailrace channel end face; 202, tailrace channel side wall; 301, first water flow outlet; 302, second water flow outlet; 303, third water flow outlet; L1, tailrace tunnel length direction; L2, tailrace channel width direction; L3, height direction. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0044] Example 1

[0045] like Figure 1-Figure 3 As shown, embodiment 1 of the present invention provides a fish gathering system, which comprises a water inlet 61, a water outlet, and a water flow channel connected between the water inlet 61 and the water outlet.

[0046] The fish-collecting system also includes a drainage structure located on one side of the water inlet 61. A barrier 91 is provided on the water channel to block fish. The barrier 91 is used to prevent fish from migrating from the downstream side of the barrier 91 to the upstream side. A first water inlet 301 is defined in the barrier 91. The water inlet 61 communicates with the water outlet through the first water inlet 301. The portion of the water channel between the first water inlet 301 and the water outlet is located within the tailrace 200. The fish-collecting system also includes a drainage structure extending from the water inlet 61 to a location downstream of the water outlet. The distance between the drainage structure and the fish holding space 11 in the tailrace width direction L2 gradually increases from the location of the drainage structure forming the water outlet to the downstream end of the drainage structure. The drainage structure is used to direct water flow from the water outlet to a location away from the water outlet. The drainage structure also directs water flow away from the water inlet 61. When fish migrate from the downstream river channel to the tailrace, they tend to swim upstream. When they encounter a suitable flow velocity in the tailrace, they will continue upstream. Therefore, they will not enter through the water inlet 61, but only through the first fish inlet 51. The third section 3 of the diversion wall is used to separate the main flow on the tailrace side and the fish attracting water on the fish gathering system side, creating a significant flow velocity difference at the water outlet.

[0047] The water inlet 61 is disposed in the tailrace 200 near the tailrace tunnel outlet 101 , so that the entire fish collecting system is located within the tailrace 200 .

[0048] A fish receiving space 11 is formed on one side of the water flow channel and communicates with the water flow channel. The water flow outlet serves as a first fish inlet 51, and a fish flow channel is formed between the first fish inlet 51 and the fish receiving space 11. The fish flow channel is located on the downstream side of the blocking member 91. Figure 1 The solid arrows on the water flow channel show the direction of water flow, and the dotted arrows show the swimming direction of fish from the first fish inlet 51 into the fish accommodation space 11.

[0049] According to the above scheme of the present invention, since fish like to move against the current, the water outlet is used as the first fish entrance, so that fish can enter from the first fish entrance as the water outlet, thereby realizing countercurrent movement. By setting the drainage structure, the water flow at the water inlet position can be guided to a position away from the water inlet, thereby reducing the flow rate at the water inlet position, so that the outflow flow rate reaches a more suitable fish-attracting flow rate, and attracts fish into the fish collecting system. Since the fish holding space is located on the side of the water flow channel, that is, avoiding the position of the water flow channel, the water flow rate in the fish holding space is relatively small, which facilitates the collection of fish after the fish swim. The present invention separates the tailwater flow from the tailwater tunnel through the drainage structure, and only uses part of the flow.

[0050] The drainage structure is a drainage wall, and the fish collecting system includes a fish collecting device 7, which extends in the length direction L1 of the tailwater tunnel. A groove is formed on the side of the fish collecting device 7 facing the water flow channel, and the groove forms the fish accommodating space 11; the length direction L1 of the tailwater tunnel is the length direction of the tailwater tunnel 100; the fish collecting device 7 and the drainage structure are respectively located on both sides of the water inlet 61; the water flow channel is located between the fish collecting device 7 and the drainage wall.

[0051] According to the above solution of the present invention, the groove is formed by the fish collecting device, that is, the groove is located on one side of the water flow channel, avoiding the position with higher flow velocity, so that the flow velocity in the groove is lower, which is suitable for collecting fish.

[0052] The drainage structure is a drainage wall, comprising a first section 1 located at the water inlet 61. The first section 1 extends downstream from the water inlet 61. When viewed from above, the distance between the first section 1 and the fish aggregating device 7 along the tailrace width L2 increases from the end of the first section 1 closest to the water inlet 61 to the end farther from the water inlet 61. This tailrace width L2 is parallel to the width of the tailrace tunnel.

[0053] According to the above solution of the present invention, by providing the diversion wall, the water flow at the water inlet can be guided to a position away from the water inlet as much as possible, thereby reducing the flow velocity at the water inlet.

[0054] The drainage wall includes a first drainage wall section 1, a second drainage wall section 2, and a third drainage wall section 3 which are connected in sequence; the first drainage wall section 1 and the third drainage wall section 3 are respectively located on the upstream side and the downstream side of the second drainage wall section 2; the second drainage wall section 2 extends in the length direction L1 of the tailwater tunnel; when viewed from the top direction of the fish collecting system, from the end of the third drainage wall section 3 close to the water inlet 61 (i.e., the connection position of the second drainage wall section 2 and the third drainage wall section 3) to the other end away from the water inlet 61 (i.e., the end of the third drainage wall section 3 located on the downstream side), the distance between the third drainage wall section 3 and the fish collecting device 7 in the width direction L2 of the tailwater channel gradually increases. In this embodiment, the connection between the second drainage wall section 2 and the third drainage wall section 3 is flush with the water outlet (e.g., Figure 1 As shown). The connection between the second section 2 and the third section 3 of the diversion wall can also be arranged to be located on the upstream side of the water outlet.

[0055] According to the above scheme of the present invention, the first section 1 of the drainage wall is used to reduce the drainage flow; the second section 2 of the drainage wall is used to separate the fish-attracting water flow and the main tail water flow; the third section 3 of the drainage wall is used to guide the main tail water flow and the fish-attracting water flow on the fish collecting system side to separate, which can form a significant flow rate difference at the water outlet.

[0056] The drainage structure is equipped with a door structure 6 for adjusting the width of the water inlet 61 .

[0057] According to the above solution of the present invention, the inlet flow rate is adjusted by adjusting the width of the water inlet.

[0058] From a top-down view of the fish gathering system, the gate structure 6 can be an arc-shaped structure. The drainage structure is equipped with M gate structures 6 for adjusting the width of the water inlet 61 and M×N second fish inlets 52. The M gate structures 6 are arranged in sequence in the height direction to form an M-layer structure. The gate structure control units corresponding to each gate structure 6 are independently configured, allowing the position and opening of the water inlet 61 corresponding to each gate structure 6 to be adjusted. The second fish inlets 52 form an overall structure with M layers and N columns. M ≥ 2, N ≥ 1. The second fish inlet 52 on the mth layer of the overall structure is located at the same height as the mth gate structure 6, with 1 ≤ m ≤ M. The second fish inlets 52 on the same layer of the overall structure are arranged in sequence along the width direction L2 of the tailrace. In this embodiment 1, M is 9 and N is 2.

[0059] The width of the position of the water inlet 61 corresponding to the door structure 6 of the mth layer is:

[0060] e_m=(k_m×N×V_m×D×H×W1×(ku×((W2×H2) / (W1×H1))-ku+1)) / Q;

[0061] Where: k_m is the flow velocity variation coefficient corresponding to the height of the second fish entrance on the mth layer; V_m is the optimal fish-attracting flow velocity corresponding to the height of the second fish entrance 52 on the mth layer; D is the width of the tailwater tunnel 100; H is the water depth at the tailwater tunnel outlet 101; Q is the tailwater flow rate (i.e., the power generation flow rate of the power station unit located upstream of the fish aggregating system); W1 is the width of the second fish entrance 52, H1 is the height of the second fish entrance 52, W2 is the width of the first fish entrance 51, H2 is the height of the first fish entrance 51, and ku is the porosity of the barrier 91. The height of the second fish entrance on the mth layer can be the height of the center of the second fish entrance on the mth layer. Since the gate structure has M layers, the water inlet 61 can also be considered to have M layers. That is, the width of the water inlet 61 at the corresponding height can be adjusted by adjusting the opening of each gate structure.

[0062] When the height of the first fish entrance 51 of the mth layer is not higher than the elevation of the tailwater tunnel outlet 101, the value range of k_m is [1, 1.2]; when the height of the first fish entrance 51 of the mth layer is higher than the elevation of the tailwater tunnel outlet 101, the value range of k_m is [1.2, 1.5].

[0063] According to the above-described solution of the present invention, the gate structures at different levels can be configured with different water inlet 61 widths, thereby independently controlling the widths of the water inlet 61 at different depths. The widths of the water inlet 61 of the gate structures can be adjusted accordingly based on the appropriate water flow velocity for fish at different depths, thereby facilitating the collection of fish at different depths. In this embodiment, the height direction L3 corresponds to the water depth direction.

[0064] The width of the water inlet 61 of the gate structure 6 is e_m=(k_m×N×V_m×D×H×W1×(ku×((W2×H2) / (W1×H1))-ku+1)) / Q; wherein: D is the width of the tailwater tunnel 100; H is the water depth at the tailwater tunnel outlet 101; W1 is the width of the second fish inlet 52; H1 is the height of the second fish inlet 52 (H1); W2 is the width of the first fish inlet 51; H2 is the height of the first fish inlet 51; the first fish inlet 51 is arranged in N rows; the porosity of the blocking member 91 (which may be an escape grille) is ku; k is the velocity variation coefficient; Q is the unit power flow; V is the optimal fish-attracting velocity corresponding to the height of the second fish inlet 52. When the height of the second fish inlet 52 is not higher than the height of the tailwater tunnel outlet 101, k The value range of is [1, 1.2]. When the height of the second fish entrance 52 is higher than the elevation of the tailwater tunnel outlet 101, k The value range of is [1.2, 1.5]. The width of the water inlet 61 is the opening size of the water inlet 61 in the width direction L2 of the tailwater channel.

[0065] According to the above solution of the present invention, by setting the width of the water inlet 61 of the door structure, the flow rate of the water inlet can be adjusted to achieve a better fish-attracting flow rate for fish of corresponding height.

[0066] The fish aggregating system is installed in the tailrace 200. The water inlet 61 is positioned toward the tailrace tunnel outlet 101. The fish aggregating device 7 is positioned near a tailrace sidewall 202. The first section 1 of the diversion wall and the tailrace sidewall 202 are located on either side of the fish aggregating device 7. The water inlet 61 is formed between the gate structure 6 and the downstream end of the tailrace tunnel 100 (i.e., the turning point formed at the intersection of the tailrace tunnel 100 and the tailrace). Specifically, the width of the water inlet 61 forms an acute angle with the width L2 of the tailrace. The tailrace tunnel outlet 101 and the tailrace end surface 201 are coplanar.

[0067] The fish holding space 11 is provided with a fish collecting box 12 with an open top. The fish collecting system also includes a lifting device (not shown) for adjusting the height of the fish collecting box 12 in the height direction L3. When the fish collecting box 12 is at its lowest height, the height of the fish flow path between the water outlet and the blocking member 91 is no lower than the top of the fish collecting box 12. Fish collected in the fish holding space 11 can be transferred using conventional transfer devices.

[0068] According to the above-described embodiment of the present invention, when fish need to be collected in the fish holding space, the fish collecting box at the lowest height does not affect the movement of fish from outside the fish holding space to the fish holding space. After collecting an appropriate number of fish, the fish collecting box can be raised using the lifting device to collect the fish in the fish holding space into the fish collecting box.

[0069] like Figure 5 As shown, the fish gathering system includes a bell-mouth structure 5; the opening size of the first end of the bell-mouth structure 5 is larger than the opening size of the second end of the bell-mouth structure 5; the first end opening of the bell-mouth structure 5 forms the first fish entrance 51, and the second end opening of the bell-mouth structure 5 forms the second fish entrance 52; the first fish entrance 51 is connected to the fish holding space 11 through the second fish entrance 52; the first fish entrance 51 is located on the upstream side of the second fish entrance 52.

[0070] According to the above-described embodiment of the present invention, fish can flow upstream through the larger first opening (the first fish entrance) and the smaller second opening (the second fish entrance) of the bell-shaped structure, before entering the space between the blocking member and the mounting member. The bell-shaped structure and the dimensions of its openings facilitate upstream entry into the fish aggregating system, while the smaller second fish entrance makes it more difficult for fish within the system to escape.

[0071] The water channel is provided with a mounting member 92 connected to the bell-mouth structure 5. The second end opening of the bell-mouth structure 5 is located at the point where the bell-mouth structure 5 connects to the mounting member 92. The portion of the mounting member 92 located outside the second end opening is used to block fish from migrating from the downstream side of the mounting member 92 to the upstream side, forming a second water flow opening 302. The sidewalls of the bell-mouth structure 5 can be configured to allow or not allow water to pass through. A third water flow opening 303 may also be formed on the sidewalls of the bell-mouth structure 5. The first water flow opening 301 is connected to the first fish inlet 51, which serves as the water outlet, through the second water flow opening 302 and the third water flow opening 303.

[0072] According to the above-described embodiment of the present invention, fish within the fish gathering system cannot escape from the portion of the mounting member located outside the second end opening. Furthermore, the portion of the mounting member located outside the second end opening forms a second water flow outlet, facilitating downstream flow of water to the water flow outlet. Furthermore, in addition to the water flow passage formed by the second and first fish inlets, a water flow passage formed by the first, second, and third water flow outlets in sequence is provided, providing an additional flow passage for the water flow. This also reduces the water velocity at the fish inlet and reduces the resistance to upstream flow of fish.

[0073] The width W1 and height H1 of the second fish entrance 52 are 2 to 3 times the length of the largest fish-collecting object, ensuring that the fish can pass smoothly horizontally; the width W2 of the first fish entrance 51 is 3 to 4 times the width W1 of the second fish entrance 52, and the height H2 of the first fish entrance 51 is 3 to 4 times the height H1 of the second fish entrance 52, thus forming an obvious "entrance effect".

[0074] like Figure 4 、 Figure 6 As shown, the blocking member 91 can be formed by connecting a plurality of first connecting rods 91A arranged at intervals, and the mounting member 92 can be formed by connecting a plurality of second connecting rods 92A arranged at intervals. A first water flow port 301 is formed between two adjacent first connecting rods 91A, and a second water flow port 302 is formed between two adjacent second connecting rods 92A.

[0075] The following is a further detailed description of Example 1 of the present invention.

[0076] Currently, most fish aggregating facilities utilize pump station water replenishment systems to generate fish-attracting flow. On the one hand, the flow generated by submersible pumps is extremely limited, resulting in low fish-attracting efficiency. On the other hand, the construction and operating costs of replenishment systems are high, making them less economical. Directly utilizing power plant tailwater in the tailwater pipe or tailwater tunnel for fish aggregating results in high flow velocities, making it difficult to create a flow gradient and adjust the flow rate for different water depths, limiting fish attraction. Furthermore, current tailwater tank aggregating methods involve direct flow into the fish collection tanks, resulting in significant head losses and impacting the power generation efficiency of the power plant.

[0077] In response to the shortcomings of existing fish aggregating systems, the present invention forms a fish-attracting flow rate that can adjust to different water depths, realizes a flow field structure that can attract fish at different water depths, and at the same time reduces the impact on tailwater power generation, thereby efficiently and economically playing the role of a fish aggregating facility.

[0078] The present invention provides a fish gathering system with adjustable flow rate for different water depths, such as Figure 1-Figure 5 As shown, it includes: a tailwater diversion structure (i.e., the first section 1 of the diversion wall), a partition wall (i.e., the second section 2 of the diversion wall), a diversion wall (i.e., the third section 3 of the diversion wall), a fish collecting device 7, a sliding rail and a rotating door structure, a control platform 4, a door structure control unit, an anti-escape fence (i.e., a blocking member 91), layered anti-escape cages (i.e., a trumpet structure), a retractable fish collecting box, a lifting device, etc. Near the exit of the tailwater tunnel 100, the first section 1 of the diversion wall, the second section 2 of the diversion wall, and the third section 3 of the diversion wall are arranged in order from upstream to downstream.

[0079] The tailwater drainage structure, the partition wall, the diversion wall, and the side walls of the fish aggregating device together form the flow channel. Viewed from above, the tailwater drainage structure is arc-shaped and located near the tailwater tunnel exit. One end of the tailwater drainage structure is located near the tailwater tunnel exit, and the other end is connected to the partition wall. The tailwater drainage structure serves as a diversion mechanism, reducing the tailwater flow through the fish aggregating channel to meet the flow rate requirements for attracting fish during single-unit power generation. Viewed from above, the partition wall is linear and parallel to the length L1 of the tailwater tunnel. Viewed from above, the diversion wall is arc-shaped and connected to the partition wall. The diversion wall directs the main flow of tailwater away from the fish aggregating channel inlet (i.e., the first fish inlet 51), creating a significant velocity gradient at the inlet. Fish are more likely to flow to locations with lower velocity at this velocity gradient, thereby attracting them to the inlet and attracting them.

[0080] On the back surface of the tailwater diversion structure (i.e. Figure 2The surface of the first section 1 of the middle diversion wall (facing the revolving gate structure 6) can be provided with multiple layers of slide rails along the water depth direction. Each layer of slide rails corresponds to a revolving gate structure, and the gate structure can move along the corresponding slide rails. A gate structure control unit (not shown) can be positioned on the backside of the tailwater diversion structure. The gate structure control unit regulates the width of the water inlet 61 of each layer of the gate structure, thereby adjusting the flow rate at the corresponding water inlet at the height of each layer, thereby adjusting the fish attracting flow rate at each layer. The input terminals of each gate structure control unit are electrically connected to the control platform 4. The control platform 4 and the gate structure control unit can be located above the normal tailwater water level. The gate structure control unit and the control platform 4 can utilize existing control devices. For example, the gate structure control unit can be a motor control device, and the control platform 4 can be a single-chip microcomputer, DSP, or PLC controller.

[0081] Given the tailrace tunnel width (or tailrace tunnel width) as D, the tailrace outlet water depth as H, the second fish inlet 52 width as W1, the height as H1, the first fish inlet 51 width as W2, the height as H2, the first fish inlet 51 arranged in N rows, and the porosity of the blocking member 91 (which can be an escape grille) as ku, the width e_m of the location corresponding to the mth layer of the gate structure in the water inlet 61 approximately satisfies the following equation: e_m = (k_m × N × V_m × D × H × W1 × (ku × ((W2 × H2) / (W1 × H1)) - ku + 1)) / Q. k_m is the velocity variation coefficient. When the second fish inlet 52 in the mth layer is below the tailrace tunnel outlet elevation, k_m can be 1 to 1.2. When the second fish inlet 52 in the mth layer is above the tailrace tunnel elevation, k_m can be 1.2 to 1.5. Q is the generator flow rate. V is the optimal flow rate for attracting fish.

[0082] The fish collecting channel is formed between the blocking member 91, the fish collecting device 7 and the drainage wall.

[0083] like Figure 5 As shown, the bell-mouth structure 5 (i.e., the escape-proof cage) includes a first guide structure 5A (forming the main body of the bell-mouth structure 5) and a second guide structure 5B (forming a flow channel of fixed height and width) that are interconnected. The end of the first guide structure 5A, remote from the second guide structure 5B, is open to form a first fish entrance 51, while the end of the second guide structure 5B, remote from the first guide structure 5A, is open to form a second fish entrance 52.

[0084] Multiple bell-mouth structures 5 can be arranged in layers on the mounting member 92. The location where the bell-mouth structures 5 connect to the mounting member 92 forms a fish inlet (i.e., a second fish inlet 52). The first fish inlet 51 of the bell-mouth structures 5 forms a water outlet, which is located between the fish aggregating device 7 and the partition wall.

[0085] Along the length of the tailrace tunnel, a fish holding space 11 (serving as a fish resting area) is located between the blocking member 91 and the mounting member 92. A fish collection box 12 can be placed at the bottom of the fish holding space 11. Once a certain number of fish have gathered, the fish collection box is lifted by the lifting device (not shown) of the fish collecting device 7 to transfer the fish. The fish holding space 11 is shielded from the main flow channel, resulting in a very low flow rate. Fish entering through the bell-shaped structure 5 and swimming upstream will not have to swim against the main flow channel and will instead rest in the fish holding space 11, where the flow rate is lower.

[0086] When a single unit is generating electricity, the tailwater flow rate controlled by the first section 1 of the diversion wall meets the required flow rate for attracting fish. At this point, the width of the water inlet 61 of each layer of the gate structure 6 can be adjusted to achieve the optimal flow rate for attracting fish. When multiple units are generating electricity simultaneously, the tailwater level and flow rate will increase significantly. At this time, the gate structure control unit adjusts the width of the water inlet 61 of each layer of the gate structure to achieve the optimal flow rate for attracting fish.

[0087] In a specific application of this embodiment, a hydropower station, a typical high-head dam, utilizes a fish hoist system for dam crossing. The fish aggregating system of the present invention was deployed near the tailrace outlet (i.e., near the tailrace tunnel exit). The station has two turbines per tunnel, with a single turbine generating a flow rate of 424 m³ / s, while the dual turbines generate a flow rate of 848 m³ / s. Fish population statistics and swimming ability tests revealed that the present invention primarily targets schizothorax and catfish. Schizothorax is primarily found in the middle and lower water layers, with a body length ranging from 22.5 cm to 41 cm, and an average body length of 30.9 cm. The critical flow velocity for attracting fish is 0.89 m / s, and the rapid swimming flow velocity is 1.26 m / s. Therefore, the optimal flow velocity for attracting schizothorax in this project is between 0.89 m / s and 1.26 m / s. Catfish are bottom fish with a body length of 12cm to 18cm and an average body length of 14cm. The critical swimming speed is 1.35m / s and the breakthrough swimming speed is 2m / s. The optimal flow velocity range for attracting fish is 1.35m / s to 2m / s. Therefore, the optimal flow velocity range for attracting catfish in this project is 1.35m / s to 2m / s.

[0088] When a single unit is operating, the fish aggregating system according to the present invention has a minimum distance between the end of the diversion structure and the end of the tailrace tunnel (the distance between the end of the diversion structure and the end of the tailrace tunnel when viewed from above) of 4 meters. The width and height of the second fish inlet 52 are 0.6 meters and 0.9 meters, respectively. The width and height of the first fish inlet 51 are 2 meters and 3 meters, respectively. The porosity of the blocking member 91 (which may be an anti-escape grille) is 0.6. The water depth at the tailrace outlet is 27 meters, and the gate structure is arranged in nine layers. The velocity variation coefficient corresponding to the bottom gate structure (i.e. the bottom three-layer gate structure) is 1.0. Through calculation, it can be concluded that the width of the water flow inlet corresponding to the optimal fish-attracting flow rate is 2.9m~4.3m; the velocity variation coefficient corresponding to the middle gate structure (i.e. the middle three-layer gate structure) is 1.2. Through calculation, it can be concluded that the width of the water flow inlet corresponding to the optimal fish-attracting flow rate is 2.4m~3.4m; the velocity variation coefficient of the surface gate structure (i.e. the top three-layer gate structure) is 1.5. Through calculation, it can be concluded that the width of the water flow inlet corresponding to the optimal fish-attracting flow rate is 3.0m~4.3m. By controlling the gate structure, the width of the water inlet 61 corresponding to the surface gate structure (i.e., the gate structure located in the top three layers in height) was adjusted to ensure that the minimum distance between the gate structure end (i.e., the end forming the water inlet) and the tailrace tunnel end was approximately 3.6 meters (the value near the middle of the calculated width range, the same applies below). The width of the water inlet 61 corresponding to the middle gate structure (i.e., the gate structure located in the fourth to sixth layers in height) was adjusted to ensure that the minimum distance between the gate structure end (i.e., the end forming the water inlet) and the tailrace tunnel end was approximately 2.9 meters. The gate structure below the bottom layer (i.e., the gate structure located in the bottom three layers in height) was adjusted to ensure that the water inlet width was 3.7 meters. CFD numerical simulations were used to analyze the flow field of the fish aggregating system during single-unit operation. The average flow velocity at the bottom layer fish inlet was 1.8 m / s, and the average flow velocity at the middle and surface layer fish inlet was 0.9 m / s. The flow velocities at the fish inlet at each layer were within the optimal fish attraction range, which was close to the results calculated by the approximate formula. At the same time, the diversion wall squeezes the main flow, causing it to deviate to the other side. A significant velocity difference is formed between the outlet of the fish gathering system and the surrounding flow field, creating a good flow field for attracting fish. The fish holding space presents a reflux flow pattern, which is suitable for fish to gather in the lounge. Figure 7 、 Figure 8 As shown, the red area is the area with higher flow rate, and the dark blue and blue-green area is the area with lower flow rate. Figure 7 On the horizontal section, Figure 8 In the cross-section, the flow velocity on the fish-collecting system side is more suitable, while the flow velocity on the main tailwater side is higher. Specifically, the flow velocity in the water channel formed by the fish-collecting system is relatively low, while the area outside the diversion wall forms an area with higher flow velocity. Due to the arrangement of the diversion wall, the flow velocity in the water channel formed by the fish-collecting system is relatively low, which is suitable for fish to enter the water channel through the first fish inlet.

[0089] When the unit is operating at full power, the control system adjusts the minimum distance between the end of the bottom-layer gate structure and the end of the tailwater tunnel to approximately 1.8 meters, the minimum distance between the end of the middle-layer gate structure and the end of the tailwater tunnel to approximately 1.5 meters, and the minimum distance between the end of the surface-layer gate structure and the end of the tailwater tunnel to approximately 1.8 meters. At this time, the average flow velocity at the bottom-layer fish inlet remains at approximately 1.8 meters per second, and the average flow velocity at the middle-surface fish inlet remains at 0.9 meters per second, both within the optimal flow rate range for attracting fish. The head loss of the entire fish-aggregating system increases by approximately 0.05 meters when a single unit is operating, and by 0.21 meters when the unit is operating at full power. This increase in head loss is minimal, and has minimal impact on the power generation of the power station.

[0090] Example 2

[0091] The main difference between this embodiment 2 and embodiment 1 is that part of the fish gathering system is arranged in the tailrace channel, and the other part is arranged in the tailrace tunnel.

[0092] like Figure 9 As shown, the first section 1 of the diversion wall and the gate structure 6 extend into the tailrace tunnel 100. The water inlet 61 is formed between the gate structure 6 and the tailrace tunnel sidewall 102, such that the water inlet 61 is located at the tailrace tunnel outlet 101. Other structures in Example 2 can refer to Example 1. In this embodiment, the width direction of the water inlet 61 is parallel to the width direction L2 of the tailrace channel.

[0093] Example 3

[0094] The main difference between this embodiment 3 and embodiment 1 is that the fish collecting box is not provided in the fish holding space, but is replaced by a baffle. The fish collecting device 7 is also connected to the baffle 71; the baffle 71 has a first state and a second state. The first guide groove 72 and the second guide groove 73 are respectively provided on the opposite walls of the fish holding space 11. Figure 10 、 Figure 11 As shown. Figure 10 As shown, when the baffle 71 is in the first state, the baffle 71 is located in the first guide groove 72, and the fish accommodating space 11 is connected to the water flow channel; Figure 11 As shown, when the baffle 71 is in the second state, the baffle 71 separates the fish accommodating space 11 and the water flow channel, and the baffle 71 extends into the second guide groove 73.

[0095] Example 4

[0096] The main difference between the embodiment 4 of the present invention and the embodiment 1 is that the blocking member can be used as follows: Figure 12The difference between the blocking member of the fourth embodiment and the first embodiment is that the blocking member 91 can adopt a double-layer structure.

[0097] Example 5

[0098] The main difference between Example 5 and Example 1 is that the diversion wall comprises a second diversion wall section 2 and a third diversion wall section 3 (not shown), which are connected in sequence. The second diversion wall section 2 extends downstream from the water inlet and in the length direction L1 of the tailrace tunnel. The third diversion wall section 3 extends from the downstream end of the second diversion wall section 2 to the water outlet.

[0099] The fixed end of the gate structure can be mounted on a structure opposite the second section 2 of the diversion wall. If the second section 2 of the diversion wall is located in the tailrace (similar to the position of the first section 1 of the diversion wall in Example 1), the fixed end of the gate structure can be mounted on the fish aggregating device 7. If the second section 2 of the diversion wall extends into the tailrace tunnel (similar to the position of the first section 1 of the diversion wall in Example 2), the fixed end of the gate structure can be mounted on the side wall 102 of the tailrace tunnel.

[0100] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0101] The embodiments of the present invention have been described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention. After reading the present invention, modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the claims appended to this application. In the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

Claims

1. A fish collecting system, comprising a water inlet (61), a water outlet, and a water flow channel connected between the water inlet (61) and the water outlet, characterized in that: The water flow channel is provided with a blocking member (91) for blocking fish; the blocking member (91) is provided with a first water flow opening (301); The water inlet (61) is arranged at the tailwater tunnel outlet (101), so that part of the water flow channel is located in the tailwater tunnel (100), or the water inlet (61) is arranged in the tailwater channel (200) at a position close to the tailwater tunnel outlet (101); A fish accommodating space (11) communicating with the water flow channel is formed on one side of the water flow channel; the water flow outlet forms a first fish inlet (51), and a fish flow channel is formed between the first fish inlet (51) and the fish accommodating space (11); the fish flow channel is located on the downstream side of the blocking member (91); The fish collecting system further comprises a drainage structure extending from a water inlet (61) to a downstream portion of a water outlet; the fish accommodating space (11) and the drainage structure are respectively located on both sides of the water flow channel; and the distance between the drainage structure and the fish accommodating space (11) in the width direction (L2) of the tailwater channel gradually increases from the position of the drainage structure where the water outlet is formed to the end of the drainage structure located on the downstream side.

2. The fish aggregating system according to claim 1, characterized in that: The fish gathering system comprises a fish gathering device (7), the fish gathering device (7) extending in the length direction (L1) of the tailwater tunnel, a groove formed on a side of the fish gathering device (7) facing the water flow channel, and the groove forming the fish accommodating space (11).

3. The fish aggregating system according to claim 1, characterized in that: The drainage structure is a drainage wall, and the drainage wall comprises a first drainage wall section (1) arranged at the water inlet (61); When viewed from above the fish collecting system, the distance between the first section (1) of the diversion wall and the fish accommodation space (11) in the width direction (L2) of the tailwater channel gradually increases from one end of the first section (1) of the diversion wall close to the water inlet (61) to the other end away from the water inlet (61).

4. The fish aggregating system according to claim 3, characterized in that: The drainage wall comprises a first drainage wall section (1), a second drainage wall section (2), and a third drainage wall section (3) which are connected in sequence; the first drainage wall section (1) and the third drainage wall section (3) are respectively located on the upstream side and the downstream side of the second drainage wall section (2); The second section (2) of the diversion wall extends in the length direction (L1) of the tailwater tunnel; When viewed from above the fish gathering system, the distance between the third section (3) of the diversion wall and the fish accommodation space (11) in the width direction (L2) of the tailwater channel gradually increases from one end of the third section (3) of the diversion wall close to the water inlet (61) to the other end away from the water inlet (61); The connection between the second section (2) of the drainage wall and the third section (3) of the drainage wall is flush with the water outlet, or the connection between the second section (2) of the drainage wall and the third section (3) of the drainage wall is located on the upstream side of the water outlet.

5. The fish aggregating system according to claim 2, characterized in that: The diversion structure is equipped with a gate structure (6) for adjusting the width of the water inlet (61); the fish collecting system is arranged in the tailwater channel (200), the water inlet (61) is arranged toward the tailwater tunnel outlet (101), the fish collecting device (7) is arranged near a tailwater channel side wall surface (202), the water flow channel and the tailwater channel side wall surface (202) are respectively located on both sides of the fish collecting device (7), and the water inlet (61) is formed between the gate structure (6) and the end of the tailwater tunnel (100) located on the downstream side; or The diversion structure is equipped with a gate structure (6) for adjusting the width of a water inlet (61); at least a portion of the diversion structure and the gate structure (6) extend into the tailwater tunnel (100), and the water inlet (61) is formed between the gate structure (6) and the side wall surface (102) of the tailwater tunnel.

6. The fish aggregating system according to claim 2, characterized in that: The fish accommodating space (11) is provided with a fish collecting box (12), the upper end of the fish collecting box (12) is open, and the fish collecting system further comprises a lifting device for adjusting the height position of the fish collecting box (12) in a height direction (L3); when the fish collecting box (12) is at the lowest height position, the height of the fish flow channel between the water outlet and the blocking member (91) is not lower than the height of the top end of the fish collecting box (12); and / or The fish collecting device (7) is further connected to a baffle (71); the baffle (71) has a first state and a second state; when the baffle (71) is in the first state, the fish accommodating space (11) is in communication with the water flow channel; when the baffle (71) is in the second state, the baffle (71) separates the fish accommodating space (11) from the water flow channel.

7. The fish aggregating system according to any one of claims 1 to 6, characterized in that: The fish gathering system includes a trumpet-shaped structure (5); The opening size of the first end of the bell-mouth structure (5) is larger than the opening size of the second end of the bell-mouth structure (5); The first end opening of the bell-mouth structure (5) forms the first fish entrance (51), and the second end opening of the bell-mouth structure (5) forms the second fish entrance (52); The first fish inlet (51) is connected to the fish accommodation space (11) through the second fish inlet (52); The first fish inlet (51) is located on the downstream side of the second fish inlet (52).

8. The fish aggregating system according to claim 7, characterized in that: The water flow channel is provided with a mounting member (92) connected to the bell mouth structure (5); The second end opening of the bell-mouth structure (5) is located at a position where the bell-mouth structure (5) is connected to the mounting member (92); The portion of the mounting member (92) located outside the second end opening is used to block fish and forms a second water flow outlet (302); a third water flow outlet (303) is formed on the side wall of the bell-mouth structure (5).

9. The fish aggregating system according to claim 7, characterized in that: The width and height of the second fish entrance (52) are 2 to 3 times the length of the largest fish collection object; the width of the first fish entrance (51) is 3 to 4 times the width of the second fish entrance (52), and the height of the first fish entrance (51) is 3 to 4 times the height of the second fish entrance (52).

10. The fish aggregating system according to claim 7, characterized in that: The drainage structure is equipped with M gate structures (6) for adjusting the width of the water inlet (61) and M×N second fish inlets (52); the M gate structures (6) are arranged in sequence in the height direction (L3) to form an M-layer structure, and the gate structure control units corresponding to the respective gate structures (6) are independently arranged; the respective second fish inlets (52) form an overall structure having M layers and N columns; M≥2, N≥1; the second fish inlet (52) located at the mth layer in the overall structure is located at the same height as the mth gate structure (6), and 1≤m≤M; The second fish inlets (52) located at the same layer in the overall structure are arranged sequentially in the width direction (L2) of the tailrace; The width of the position corresponding to the m-th layer gate structure (6) in the water inlet (61) is: e_m=(k_m×N×V_m×D×H×W1×(ku×((W2×H2) / (W1×H1))-ku+1)) / Q; Wherein: k_m is the velocity variation coefficient corresponding to the height position of the second fish entrance (52) of the mth layer; V_m is the optimal fish-attracting velocity corresponding to the height position of the second fish entrance (52) of the mth layer; D is the width of the tailwater tunnel (100); H is the water depth at the tailwater tunnel outlet (101); Q is the power generation tailwater flow rate; W1 is the width of the second fish entrance (52), H1 is the height of the second fish entrance (52), W2 is the width of the first fish entrance (51), H2 is the height of the first fish entrance (51), and ku is the porosity of the barrier (91); When the height of the first fish entrance (51) of the mth layer is not higher than the elevation of the tailwater tunnel outlet (101), the value range of k_m is [1, 1.2]. When the height of the first fish entrance (51) of the mth layer is higher than the elevation of the tailwater tunnel outlet (101), the value range of k_m is [1.2, 1.5].

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