Water diversion type cascade series hydropower station group

Abstract

The invention provides a water diversion type cascade series hydropower station group. Each stage of hydropower station comprises a water inlet, a water diversion tunnel, a surge chamber, a branch pipe, a plant, a flow balance discharge hole, an energy dissipation facility, a tailrace tunnel and a regulating reservoir. Wherein the water inlet of the first-stage hydropower station is communicated with a reservoir, and the last-stage hydropower station is connected with a downstream river channel; a flow balance discharge hole is arranged below a plant of each stage of hydropower station, the flow balance discharge hole is connected with the plant in parallel, the upstream of the flow balance discharge hole is separated from a diversion tunnel through a branch pipe, the downstream of the flow balance discharge hole is communicated with a regulating reservoir, the flow balance discharge hole is provided with a valve chamber, a discharge ball valve and a flow regulating valve are mounted in the valve chamber, and an energy dissipation facility is arranged at the downstream of the valve chamber. The water flow stably enters the adjusting tank. On the premise that work of other hydropower station units in the cascade is not affected, the flow can still be normally lowered into a downstream reservoir, and therefore it is guaranteed that power generation of upstream and downstream hydropower stations is not affected.

Description

Technical Field

[0001] The invention belongs to the technical field of hydropower station construction and hydropower station operation and maintenance, and in particular relates to a method for normal overcurrent power generation of a water-diverting cascade series hydropower station under complex conditions, and specifically designs a water-diverting cascade series hydropower station group. Background Art

[0002] The diversion cascade hydropower station is usually a multiple hydropower station connected in series by multiple diversion tunnels with gentle slopes in river sections with large river slopes and concentrated drop heights, which are not convenient for damming. However, in the process of hydropower station operation and maintenance, the failure or maintenance of individual units is inevitable. When a unit fails or is under maintenance, the diversion cascade hydropower station will close the ball valve of the unit. Since the upper tailwater tunnel of the tunnel diversion cascade hydropower station is directly connected to the lower diversion tunnel, the closing of the ball valve of the unit will cause the water to be unable to discharge, and then the units of the upstream and downstream hydropower stations connected to the unit will also have to close the ball valves to avoid water overflow and safety accidents. The flexibility of this type of hydropower station group scheduling method is poor. Once a unit fails, the upstream and downstream hydropower stations will not be able to generate electricity normally, resulting in a large amount of electricity waste and a large impact on the stability of the power grid. Therefore, in the prior art, the water diversion cascade hydropower station lacks resilience during the operation and maintenance process. Once a failure occurs in one stage, the upstream and downstream hydropower stations cannot generate electricity normally, resulting in its practical significance being greatly reduced and unable to be effectively applied. Summary of the invention

[0003] In order to solve the current technical problems, the main purpose of the present invention is to provide a water diversion type cascade series hydropower station group. This construction and scheduling method can transfer the flow normally to the downstream reservoir without affecting the operation of other hydropower station units in the cascade, thereby ensuring that the power generation of upstream and downstream hydropower stations is not affected, which not only maximizes the overall benefits of the cascade hydropower stations, but also ensures the safety and stability of the power grid.

[0004] In order to realize the above technical features, the object of the present invention is achieved as follows: a water diversion type cascade series hydropower station group, the hydropower station group is built in a mountain with a height difference, and multiple hydropower stations are connected in series through a tunnel in the mountain; Each hydropower station includes water intake, diversion tunnel, surge chamber, branch pipe, powerhouse, flow balance discharge tunnel, energy dissipation facilities, tailwater tunnel and regulating pond. The water inlet of the hydropower station at the first level is connected to the reservoir, and the hydropower station at the last level is connected to the downstream river; A flow balancing discharge hole is arranged under the powerhouse of each level of hydropower station. The flow balancing discharge hole is connected in parallel with the powerhouse. The upstream of the flow balancing discharge hole is separated from the water diversion tunnel through a branch pipe, and the downstream is connected to the regulating tank.

[0005] The flow balance discharge hole is provided with a valve chamber, a discharge ball valve and a flow regulating valve are installed in the valve chamber, and an energy dissipation facility is provided downstream of the valve chamber to ensure that water flows smoothly into the regulating tank.

[0006] The plant building is provided with unit ball valves and units.

[0007] There is at least one diversion tunnel for each level of hydropower station.

[0008] The regulating pond is provided with three water levels, namely the upper limit water level, the normal water storage level and the dead water level. The water level can be adjusted between the dead water level and the upper limit water level; the storage capacity between the normal water storage level and the dead water level is the lower regulating storage capacity, and the storage capacity between the normal water storage level and the upper limit water level is the upper regulating storage capacity.

[0009] The end of a single diversion tunnel at each level is connected to at least one diversion branch tunnel. The other end of the diversion branch tunnel is connected to the unit ball valve and unit inside the plant. The unit is connected to the regulating tank through the tailwater tunnel.

[0010] The valve room is set up separately or shared with the factory building.

[0011] The flow balance discharge holes of adjacent diversion tunnels are arranged in the middle part of the diversion tunnels and share a valve room and energy dissipation facilities.

[0012] The present invention has the following beneficial effects: 1. The present invention, based on the tunnel water diversion cascade hydropower station, constructs a flow balance discharge tunnel connected from the water diversion tunnel to the regulating tank through the bottom of the plant building to ensure normal flow when a unit of a certain level of hydropower station fails or is under maintenance, thereby ensuring normal maintenance of the unit.

[0013] 2. A valve chamber is provided downstream of the flow balance discharge hole of the present invention, and during operation and maintenance, it is opened and closed symmetrically with the ball valve of the faulty or overhauled unit. A flow regulating valve is provided in the valve chamber, thereby being able to well control the size of the downstream discharge flow.

[0014] 3. The present invention constructs energy dissipation facilities in the downstream area of ​​the valve chamber, thereby being able to eliminate water flow energy and reduce water head to avoid damage to the tailwater tunnel.

[0015] 4. The excess water in the water-diversion cascade hydropower station group described in the present invention will enter the regulating tank from the flow balance discharge hole, without the need to build an additional drainage tunnel downstream of the plant.

[0016] 5. In the present invention, when a unit of a hydropower station at a certain level in a cascade hydropower station fails or needs to be repaired, the ball valve of the flow balance discharge hole is immediately opened after the ball valve of the failed unit of the hydropower station at that level is closed.

[0017] 6. The dispatching method of the present invention can ensure the normal water flow and power generation of upstream and downstream cascade hydropower stations when a unit of a certain level of hydropower station fails or needs maintenance, thereby maximizing the overall power generation benefits of the cascade hydropower stations.

[0018] 7. The scheduling method of the present invention has greater flexibility and adjustability. In the dry season, in order to ensure the maximum water benefit, all upstream and downstream units related to the overhauled or faulty units can be shut down and the water can be stored in the reservoir; in the flood season, when the unit is under overhaul or faulty, the water can be discharged into the downstream through the flow balance discharge hole to ensure power generation of the upstream and downstream units.

[0019] 8. The dispatching method of the present invention can ensure upstream and downstream power generation when the unit fails or is under maintenance, thereby reducing the impact on the stability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1 It is a schematic diagram of a water diversion type cascade series hydropower station group according to an example of the present invention.

[0022] Figure 2 It is a longitudinal section of a hydropower station of a certain level in the example of the present invention Figure 3 It is a plan view of a hydropower station of a certain level in an example of the present invention.

[0023] Figure 4 It is a diagram of the water level changes in the upstream regulating tank of the accident unit during the operation and maintenance process in the example of the present invention.

[0024] Figure 5 It is a diagram of the water level changes in the regulating tank downstream of the accident unit during the operation and maintenance process in the example of the present invention.

[0025] In the figure: first-level hydropower station 1, second-level hydropower station 2, third-level hydropower station 3, fourth-level hydropower station 4, mountain 5, reservoir 6, downstream river 7; Water diversion tunnel 101, surge chamber 102, branch pipe 103, flow balance discharge tunnel 104, powerhouse 105, valve room 106, energy dissipation facility 107, tailwater tunnel 108, regulating tank 109, water inlet 110, unit ball valve 111, unit 112, discharge ball valve 113, flow regulating valve 114, upper water level 115, normal water storage level 116, dead water level 117, water diversion branch tunnel 118. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0027] Embodiment 1: See also Figure 1-5A water diversion cascade series hydropower station group, the hydropower station group is built in a mountain 5 with a height difference, and multiple hydropower stations are connected in series through tunnels in the mountain 5; each level of the hydropower station includes a water inlet 110, a water diversion tunnel 101, a surge chamber 102, a branch pipe 103, a plant 105, a flow balance discharge tunnel 104, an energy dissipation facility 107, a tailwater tunnel 108 and a regulating pond 109; the water inlet 110 of the hydropower station at the first level is connected to the reservoir 6, and the hydropower station at the last level is connected to the downstream River channel 7; A flow balance discharge hole 104 is arranged below the powerhouse 105 of each hydropower station. The flow balance discharge hole 104 is connected in parallel with the powerhouse 105. The upstream of the flow balance discharge hole 104 is separated from the water diversion tunnel 101 through a branch pipe 103, and the downstream is connected to the regulating tank 109. The flow balance discharge hole 104 is provided with a valve chamber 106, and a discharge ball valve 113 and a flow regulating valve 114 are installed in the valve chamber 106. An energy dissipation facility 107 is arranged downstream of the valve chamber 106 to ensure that the water flows smoothly into the regulating tank 109. By adopting this design method of the present invention, when a unit of the cascade hydropower station fails, the water flow can still enter the regulating tank through the flow balance discharge hole, and the regulating tank uses its own water volume to temporarily ensure smooth upstream and downstream flows. After the water flow is normal, the flow is controlled by the flow regulating valve so that the flow in the regulating tank gradually returns to the normal water storage level.

[0028] Among them, the flow balance discharge hole 104 can be quickly started when the plant unit fails and is closed, which can minimize the storage capacity of the regulating tank and save engineering costs.

[0029] Each level of the cascade hydropower station described in the present invention needs to be equipped with a branch pipe, a flow balance discharge hole, a discharge ball valve, a flow regulating valve, an energy dissipation facility and a regulating pool of the lower hydropower station at the rear end of the water diversion tunnel. Different from the conventional tunnel water diversion cascade hydropower station, the excess water in the water diversion cascade series hydropower station group described in the present invention will smoothly flow into the downstream from the flow balance discharge hole, without the need to set up an additional drainage tunnel at the tailwater tunnel.

[0030] Furthermore, a unit ball valve 111 and a unit 112 are arranged inside the plant 105. The unit ball valve 111 facilitates rapid closure when a unit fails, thereby facilitating maintenance or repair of the unit.

[0031] Furthermore, each level of the hydropower station has at least one diversion tunnel 101. Multiple diversion tunnels 101 are used to supply water to multiple units, thereby improving power generation efficiency.

[0032] Furthermore, the regulating pool 109 is provided with three water levels, namely, an upper water level 115, a normal water level 116 and a dead water level 117. The water level can be adjusted between the dead water level 117 and the upper water level 115. The storage capacity between the normal water level 116 and the dead water level 117 is the lower regulating storage capacity, and the storage capacity between the normal water level 116 and the upper water level 115 is the upper regulating storage capacity. The three water levels mentioned above ensure the subsequent normal water level regulation, thereby ensuring stable power generation.

[0033] Furthermore, the end of each single diversion tunnel 101 is connected to at least one diversion branch tunnel 118, and the other end of the diversion branch tunnel 118 is respectively connected to the unit ball valve 111 and the unit 112 inside the powerhouse 105, and the unit 112 is connected to the regulating tank 109 through the tailwater tunnel 108. The above-mentioned multiple diversion branch tunnels 118 facilitate water supply to multiple different units.

[0034] Furthermore, the valve chamber 106 is provided separately or shared with the plant 105. The above arrangement reduces the construction cost.

[0035] Furthermore, the flow balance discharge holes 104 of adjacent diversion tunnels 101 are arranged in the middle of the diversion tunnel 101, and share a valve chamber 106 and an energy dissipation facility 107. The above arrangement reduces the construction cost.

[0036] Embodiment 2: A method for constructing a water diversion type cascade series hydropower station group, comprising the following steps: Step 1: a branch pipe 103 is arranged downstream of a diversion tunnel 101 of a diversion type cascade hydropower station group; Step 2: One end of the branch pipe 103 leads to the powerhouse 105 for power generation, and the other end bypasses the bottom of the powerhouse 105 to set a flow balance discharge hole 104 connected to the regulating tank 109; Step 3: a valve chamber 106 is set at a suitable position of the flow balance discharge hole 104 in step 2, and a discharge ball valve 113 and a flow regulating valve 114 are installed in the valve chamber 106; Step 4: In step 3, an energy dissipation device 107 is provided downstream of the valve chamber 106; Step 5: Setting a regulating pond 109 of the next-level hydropower station behind the tailwater tunnel 108 downstream of the powerhouse 105; Step 6: Subsequent multi-level hydropower stations are constructed in this way until the final hydropower station.

[0037] Furthermore, the flow balance discharge hole 104 described in step 2 is used for balancing the flow during unit failure or maintenance; the flow balance discharge hole 104 is used to balance the units corresponding to the water diversion tunnel 101, and the design flow of the water diversion tunnel remains unchanged, and the tunnel diameter remains unchanged; Furthermore, the discharge ball valve 113 described in step 3 is used to control whether the water flows into the downstream through the flow balance discharge hole 104; Furthermore, the energy dissipation facility 107 described in step 4 is used to eliminate water flow energy and reduce water head to avoid causing flow disturbance in the regulating tank 109 and affecting water diversion and power generation; Furthermore, the regulating tank 109 described in step 5 is used to adjust the flow rate during a short period of time when the ball valves 111 of the upstream and downstream units are opened and closed, to ensure that the flow upstream is not blocked and the flow downstream is continuous.

[0038] Embodiment 3: A method for dispatching a water diversion type cascade series hydropower station group, comprising the following steps: Step 1: When all the units in the cascade series hydropower station group are operating normally, the discharge ball valve 113 of the flow balance discharge hole 104 is closed, and the water flows from the upstream through the water flow units of the multi-stage hydropower station to generate electricity normally; Step 2: When a unit in the cascaded hydropower station group fails or needs to be repaired, the unit ball valve 111 of the failed unit of the hydropower station is closed, and the discharge ball valve 113 of the flow balance discharge hole 104 is opened to adjust the flow control valve 114; Step 3: The water flows through the flow balance discharge hole 104 and the energy dissipation facility 107 and enters the regulating tank 109, and then flows into the downstream cascade hydropower station; at the same time, the faulty unit is inspected or repaired; Step 4: After the unit is overhauled or repaired, adjust the flow regulating valve 114, close the discharge ball valve 113 of the flow balance discharge hole 104, and open the unit ball valve of the original faulty unit, and the cascade hydropower station resumes normal power generation.

[0039] Embodiment 4: According to different water inflows, the dispatching plan is determined to ensure maximum power generation and minimum impact on the power grid, including: During the flood season: Step 1: When all units in the cascade hydropower station are working normally, the discharge ball valve of the flow balance discharge hole is closed, and water flows from upstream through the units of the multi-stage hydropower station to generate electricity normally; Step 2: When a unit in a cascade hydropower station fails or needs to be repaired, the ball valve of the unit of the failed unit of the hydropower station is closed, and the discharge ball valve of the flow balance discharge hole is immediately opened; When the ball valve of the first-stage hydropower station's powerhouse unit is closed, the inflow to its second-stage regulating pool decreases, and the water level will drop briefly. The discharge ball valve of the flow balance discharge hole of the first-stage hydropower station opens, and the water level of its second-stage regulating pool drops slowly and gradually rises before reaching the dead water level. The flow is adjusted by the flow regulating valve to restore the water level of the second-stage regulating pool to the normal water storage level. Since the downstream second-stage regulating pool plays a regulating role, the water level of the regulating pool of the third-stage and subsequent cascade hydropower stations remains unchanged; When the ball valve of the unit in the second-stage hydropower station plant is closed, the outflow of the second-stage regulating pool will decrease, the water level will rise temporarily, the inflow of the third-stage regulating pool will decrease, the water level will drop temporarily, the discharge ball valve of the flow balance discharge hole of the second-stage hydropower station will open, the water level of the second-stage regulating pool will rise slowly, and will gradually drop before reaching the upper limit water level, the water level of the third-stage regulating pool will drop slowly, and will gradually rise before reaching the dead water level, the flow rate will be adjusted by the flow regulating valve to restore the water level of the second and third-stage regulating pools to the normal water storage level. The water level of the regulating pool of the cascade hydropower stations above the second level and below the third level remains unchanged; the subsequent multi-level power stations are analogous until the ball valve of the unit of the hydropower plant building of the last hydropower station is closed, the outflow of the last regulating pool is reduced, the water level will rise briefly, the discharge ball valve of the flow balance discharge hole of the last hydropower station is opened, the water level of the second regulating pool rises slowly, and gradually decreases before reaching the upper limit water level. The flow is adjusted by the flow regulating valve to restore the water level of the last regulating pool to the normal water storage level. Since the last regulating pool plays a regulating role, the water level of its upstream regulating pool remains unchanged; Step 3: After passing through the flow balance discharge hole and energy dissipation facilities, the water flows normally through the regulating pool into the downstream cascade hydropower station. At the same time, the associated units begin to overhaul or repair the faulty units; Step 4: After the unit overhaul or repair is completed, the unit ball valve of the original faulty unit is opened, and the cascade hydropower station resumes normal power generation. The flow rate is reduced through the flow regulating valve until the discharge ball valve of the flow balance discharge hole is closed, and the water level of the upstream and downstream regulating tanks is controlled at the normal water storage level.

[0040] The dispatching method described in the present invention can ensure the normal water flow of upstream and downstream cascade hydropower stations when a unit of a certain level of hydropower station fails or needs maintenance, ensure the normal power generation of upstream and downstream cascade hydropower stations, and avoid simultaneous shutdown of cascade series hydropower stations, which not only maximizes the overall power generation benefits of the cascade hydropower stations, but also ensures the stability of the power grid.

[0041] Embodiment 5: During the dry season: Step 1: When all units in the cascade hydropower station are working normally, the discharge ball valve of the flow balance discharge hole is closed, and the water flows from the upstream through the water flow units of the multi-stage hydropower station to generate electricity normally; Step 2: When a unit in a cascade hydropower station fails or needs to be repaired, after the unit ball valve of the faulty unit of the hydropower station is closed, the discharge ball valve of the flow balance discharge hole is immediately opened, and the flow regulating valve is adjusted. The water level of the upstream and downstream regulating tanks changes briefly and returns to the normal water storage level; Step 3: Close the ball valves of the upper and lower units in series with the maintenance or faulty units step by step, and open the discharge ball valve of the flow balance discharge hole at the same time. Control the water level of the regulating pool near the normal water storage level through the flow regulating valve. Prepare an emergency plan and report it to the power grid. Before starting the emergency plan, inform the power grid to avoid the simultaneous shutdown of cascaded hydropower stations and ensure the safe and stable operation of the power grid. Step 4: Simultaneously control the flow regulating valves of the flow balance discharge holes of each cascade hydropower station to reduce the flow until the discharge ball valve is closed, reduce the amount of water discharged, and leave the water in the reservoir of the first-level hydropower station to avoid waste and maximize the overall power generation benefits of the cascade hydropower station; Step 5: After the inspection or troubleshooting is completed, open the ball valves of each level of units in turn and start normal power generation to ensure maximum power generation during the dry season.

[0042] The dispatching method described in the present invention can retain water in the reservoir of the most upstream power station during the dry season, thereby ensuring the maximum power generation income of the cascade power stations; and can reduce the impact on the stability of the power grid by preparing emergency plans and reporting to the power grid.

Claims

1. A water diversion type cascade series hydropower station group, wherein the hydropower station group is constructed in a mountain (5) with a height difference, and a plurality of hydropower stations are connected in series via a tunnel in the mountain (5); It is characterized in that Each hydropower station includes a water inlet (110), a water diversion tunnel (101), a surge chamber (102), a branch pipe (103), a powerhouse (105), a flow balance discharge tunnel (104), an energy dissipation facility (107), a tailwater tunnel (108) and a regulating pond (109); The water inlet (110) of the hydropower station at the first stage is connected to the reservoir (6), and the hydropower station at the last stage is connected to the downstream river (7); A flow balancing discharge hole (104) is arranged below the powerhouse (105) of each stage of the hydropower station. The flow balancing discharge hole (104) is connected in parallel with the powerhouse (105). The flow balancing discharge hole (104) is branched from the water diversion tunnel (101) upstream through a branch pipe (103) and connected to a regulating tank (109) downstream.

2. A water diversion type cascade series hydropower station group according to claim 1, characterized in that: The flow balance discharge hole (104) is provided with a valve chamber (106), a discharge ball valve (113) and a flow regulating valve (114) are installed in the valve chamber (106), and an energy dissipation facility (107) is provided downstream of the valve chamber (106) to ensure that water flows smoothly into the regulating tank (109).

3. A water diversion type cascade hydropower station group according to claim 1, characterized in that: The plant (105) is provided with a unit ball valve (111) and a unit (112) inside.

4. A water diversion type cascade series hydropower station group according to claim 1, characterized in that: There is at least one diversion tunnel (101) for each level of hydropower station.

5. The water diversion type cascade hydropower station group according to claim 1, characterized in that: The regulating pool (109) is provided with three water levels, namely an upper water level (115), a normal water level (116) and a dead water level (117). The water level can be adjusted between the dead water level (117) and the upper water level (115); the storage capacity between the normal water level (116) and the dead water level (117) is the lower regulating storage capacity, and the storage capacity between the normal water level (116) and the upper water level (115) is the upper regulating storage capacity.

6. A water diversion type cascade hydropower station group according to claim 3, characterized in that: The end of each single diversion tunnel (101) is connected to at least one diversion branch tunnel (118), and the other end of the diversion branch tunnel (118) is respectively connected to the unit ball valve (111) and the unit (112) inside the powerhouse (105), and the unit (112) is connected to the regulating tank (109) through the tailwater tunnel (108).

7. The water diversion type cascade hydropower station group according to claim 2, characterized in that: The valve chamber (106) is provided separately or shared with the plant building (105).

8. A water diversion type cascade hydropower station group according to claim 7, characterized in that: The flow balance discharge holes (104) of adjacent diversion tunnels (101) are arranged in the middle of the diversion tunnels (101) and share a valve chamber (106) and an energy dissipation facility (107).

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