CN111881499B - Design method of tail water enclosure of seawater pumped storage power station reservoir - Google Patents

Abstract

The invention relates to a design method of a tail water enclosure of a water reservoir of a seawater pumped storage power station, which comprises the following steps: analyzing the demand of the permeable breakwater; determining basic parameters of the breakwater; acquiring the limiting flow velocity of the water body of the penetration hole; obtaining parameters of the through-flow hole; calculating the height of the through hole; and (5) performing model experiments. The invention provides a vertical baffle type permeable breakwater which can take all functions into consideration by summarizing the basic requirements of the tail water enclosure of the seawater pumped storage power station in the aspects of wave prevention, flow penetration, sand prevention, floating prevention, easy cleaning and the like, and the vertical baffle type permeable breakwater is not easy to adsorb or hook floats from the floating prevention angle.

Description

Design method for tail water enclosure of lower reservoir of seawater pumped storage power station

technical field

The invention relates to a design method for tail water enclosure of a lower reservoir of a seawater pumped storage power station, which is a design method for a water conservancy project and a design method for an auxiliary structure of a seawater pumped storage power station.

Background technique

The pumped storage power station is created to solve the contradiction between supply and demand between the peak and trough of the power grid, and it is a way of indirect storage of electric energy. It uses the excess power in the second half of the night to drive the water pump to pump water from the lower reservoir to the upper reservoir for storage, and then releases the water to generate electricity during the day and the first half of the next day, and flows into the lower reservoir.

The seawater pumped storage power station uses the sea as the lower reservoir, and builds the upper reservoir on the coastal mountain with reasonable geographical location and topography. Under ocean boundary conditions, in addition to traditional hydraulic problems, waves will have a greater impact on the operation of pumped storage power plants. Especially in the case of large waves, large waves will spread to the vicinity of the project. On the one hand, it will affect the stability of the tailwater containment breakwater, and on the other hand, it will cause large fluctuations in the water level in the lower reservoir, which will affect the safe and stable operation of the power station. . Due to the seldom application of seawater pumped storage power plants, there is a lack of relevant research on the structural types of breakwaters that can be applied to the tail water enclosure of lower reservoirs, and the design methods are even more lacking.

Contents of the invention

In order to overcome the problems of the prior art, the present invention proposes a design method for the tail water enclosure of the lower reservoir of the seawater pumped storage power station. In the method described, the vertical baffle type permeable breakwater is selected as the basic structure of the breakwater, and various parameters of the vertical baffle type permeable breakwater are accurately determined through a series of steps, which are used for the layout of the tail water enclosure of the lower reservoir of the seawater pumped storage power station, The selection of structure types and engineering design of permeable breakwaters provide a reference for applicability.

The object of the present invention is achieved in the following way: a design method for the tail water enclosure of the lower reservoir of a seawater pumped storage power station, the tail water enclosure is at least one row of vertical baffle type permeable breakwaters, and the embankment of the permeable breakwaters The lower part of the body is provided with a number of rectangular through-flow holes, and the section from the lower edge of the through-flow holes to the bottom of the breakwater is provided with a sill. The specific steps of the method are as follows:

Step 1, analyze the requirements of permeable breakwaters: analyze the functional requirements of permeable breakwaters, and put forward the basic requirements of the permeable breakwater structures from the aspects of wave prevention, flow penetration, sand prevention, drift prevention and easy cleaning;

Step 2, determine the basic parameters of the breakwater: obtain the planned installed capacity of the power station, thereby determine the maximum intake or drainage flow Q under the planned installed capacity, and investigate the conditions of the sea area where the power station is located, including terrain and geographical location, so as to obtain the permeable breakwater The length L and the water depth d in front of the permeable breakwater; for different environmental flow conditions, according to the water level fluctuation requirements for the safe and stable operation of the power plant unit, the allowable wave height H _s behind the permeable breakwater is obtained;

Step 3. Obtain the limited flow rate of the water body in the through-hole: By investigating the hydrology and planktonic characteristics of the sea area where the power station is located, and considering the impact on the water environment in the surrounding sea area, it is obtained that the entrainment of floating objects to the through-hole and the potential for marine organisms are not easy to occur. The free through-hole water body restricts the flow velocity v;

Step 4, obtain the parameters of the through-hole: According to the requirements of the reservoir to prevent floating objects and sand-retaining, and from the aspects of easy cleaning in the later stage, stable structure, strength, flow rate requirements of the through hole and drainage flow rate requirements, the opening size and the size of the through-hole on the permeable breakwater are considered. Interval, to determine the upper and lower position limits of the opening;

Step 5. Calculating the height of the through-hole: According to the maximum water intake or discharge Q of the power station, the length of the breakwater L, the limited flow velocity v of the water in the through-hole, the width of the opening B _s , and the opening interval D _s , the opening height B of the through-hole is calculated:

Step 6, model experiment: verify whether the transmitted wave height H _t behind the embankment satisfies the requirement H _t ≤ H _s through the wave physical model test. If the requirement is met, the structure type of the permeable breakwater can be determined; The opening width B _s or height B of the orifice, and judge whether the opening scale exceeds the limit range, if it exceeds the limit range, add one or more rows of permeable breakwaters after the current breakwater to meet the transmitted wave height behind the embankment of the lower reservoir H _t ≤ H _s requirements.

The advantages and beneficial effects of the present invention are: the present invention proposes by summarizing the breakwater structure of the tailwater enclosure of the lower reservoir of the seawater pumped storage power station, including the basic requirements of wave prevention, flow penetration, sand prevention, drift prevention and easy cleaning. A structure type of permeable breakwater that can take into account various functions - vertical baffle type permeable breakwater. From the perspective of anti-drifting, vertical baffle type permeable breakwater is not easy to absorb or hook floating objects. The design method can realize the accurate determination of the structure type of the breakwater of the lower reservoir, and provides an applicability reference basis for the layout of the tail water enclosure of the lower reservoir of the seawater pumped storage power station, the selection of the structure type of the permeable breakwater and the engineering design.

Description of drawings

The present invention will be further described below in conjunction with drawings and embodiments.

Fig. 1 is a structural diagram of the vertical baffle type permeable breakwater involved in the method described in the embodiment of the present invention;

Fig. 2 is a flowchart of the design method described in the embodiment of the present invention.

Detailed ways

Example:

This embodiment is a design method for the tail water enclosure of the lower reservoir of the seawater pumped storage power station. The tail water enclosure is at least one row of vertical baffle type permeable breakwaters, and the lower part of the body 1 of the permeable breakwaters is provided with A number of rectangular through-holes 2 are provided, and sand-blocking ridges 3 are provided on the section from the lower edge of the through-holes to the bottom of the breakwater, as shown in FIG. 1 .

The design method described in this embodiment involves the enclosure of the tail water of the reservoir under the seawater pumped storage power station, and the enclosure is the breakwater in the pumped storage power station. The basic structure of the vertical baffle type permeable breakwater selected in this embodiment is a vertical plate-shaped embankment made of reinforced concrete. The plate-shaped embankment is provided with rectangular through-flow holes in the underwater part, and the through-flow holes are designed to be rectangular. The main reason is that the design and construction are relatively convenient and the cost is low. If the design is a circular hole, the length and width of the rectangular hole need to be converted into the equivalent diameter of the circular hole.

The tail water enclosure structure of the lower reservoir needs to meet the basic requirements of wave prevention and flow penetration, and these two aspects are in a mutually contradictory and mutually restrictive relationship. The structure needs to be permeable, so holes need to be opened inside the structure, and at the same time, waves from the open sea will enter the waters enclosed by the breakwater. The size of the opening determines the flow rate of water passing through the structure, and the size of the flow rate determines the size of the impact on the surrounding waters. If the opening area is larger, the flow velocity of the water body through the hole will be smaller, and the impact on the surrounding waters will be smaller, which will increase the wave energy transmitted from the open sea to the inner side of the embankment (lower reservoir), which will affect the safe and stable operation of the power station. Therefore, it is necessary to adjust the size of the opening and the structural arrangement to find a balance between wave prevention and flow penetration.

The basic idea of this embodiment is to determine the upper and lower limits of the width and height of the permeable holes of the vertical baffle type permeable breakwater, and The water body of the through hole restricts the flow rate. Calculate the height of the through-hole through the limited flow velocity of the water body of the through-hole and the relevant parameters of the corresponding permeable breakwater, then build a physical model, and verify through the model test whether the height of the through-hole is within the limit range of the allowable wave height behind the embankment, if it exceeds The limit of the allowable wave height requires adjustment of the height of the through hole. If the height of the through hole exceeds the upper and lower limits set in advance, the number of rows of breakwaters must be increased until the limit of the allowable wave height behind the dike is met. The permeable breakwater described in this embodiment is a vertical baffle type permeable breakwater. The body of the embankment is an upright flat plate. The hole restricts the flow velocity, and the height B of the opening is adjusted to achieve a balance between the structure's anti-wave and flow-through properties.

The concrete steps of described method are as follows, and the flow process of described method is as shown in Figure 1:

Step 1, analyzing the requirements of the permeable breakwater: analyzing the functional requirements of the permeable breakwater, and putting forward the basic requirements of the permeable breakwater structure in terms of wave protection, flow through, sand prevention, drift prevention and easy cleaning.

According to the objective conditions of the sea area where the power station is located, the wave protection requirements of the permeable breakwater are put forward, that is, the wave height limit behind the dike and the number of seepage flow. It is also necessary to pay attention to excessive sediment entering the tail water reservoir to prevent a large amount of sediment from accumulating in the reservoir and reduce the storage capacity. Anti-drifting and easy cleaning are to prevent too much debris from entering the tail water reservoir, and to clean up the debris conveniently.

From the perspective of anti-drifting, the permeable breakwater should adopt the vertical baffle type, and the floating objects should not be adsorbed or linked to the breakwater, and the opening height should be below the still water surface. Most of the floating objects are floating at a position more than 2 meters away from the water surface. To prevent floating objects, no holes shall be opened 2 meters below the still water surface to prevent floating objects from entering the tail reservoir.

The sediment at the bottom of the water is easy to rise under the push of the waves, and the bottom of the breakwater is equipped with a sand barrier to block the rising sediment.

Step 2, determine the basic parameters of the breakwater: obtain the planned installed capacity of the power station, thereby determine the maximum intake or drainage flow Q under the planned installed capacity, and investigate the conditions of the sea area where the power station is located, including terrain and geographical location, so as to obtain the permeable breakwater The length L and the water depth d in front of the permeable breakwater; for different environmental flow conditions, according to the water level fluctuation requirements for the safe and stable operation of the power plant unit, the allowable wave height H _s behind the permeable breakwater is obtained.

Aiming at different environmental flow conditions and according to the maximum installed capacity of the power plant, the flow velocity of the water entering and exiting the through-hole of the permeable breakwater and the arrangement length of the breakwater are obtained. According to the water level fluctuation requirements for the safe and stable operation of the power station unit, the allowable wave height behind the permeable breakwater in the lower reservoir is obtained. Therefore, the maximum intake or drainage flow Q, the length L of the permeable breakwater, the water depth d in front of the permeable breakwater, and the allowable wave height H _s behind the embankment are all determined by the power station or the environment of the power station, which are known as design numbers.

Step 3. Obtain the limited flow rate of the water body in the through-hole: By investigating the hydrology and planktonic characteristics of the sea area where the power station is located, and considering the impact on the water environment in the surrounding sea area, it is obtained that the entrainment of floating objects to the through-hole and the potential for marine organisms are not easy to occur. The free through-hole water restricts the flow velocity v.

The condition for determining the flow rate limitation of the water body in the throughhole is mainly the speed at which marine organisms can break free, which is mainly for the protection of marine organisms, that is, mainly due to environmental considerations. At the same time, this flow rate is also difficult for floating objects to be sucked into the throughhole. However, since the through-flow holes are generally arranged at a relatively deep position in the water, floating objects can be prevented from being sucked into the through-flow holes.

Step 4, obtain the parameters of the through-hole: According to the requirements of the reservoir to prevent floating objects and sand-retaining, and from the aspects of easy cleaning in the later stage, stable structure, strength, flow rate requirements of the through hole and drainage flow rate requirements, the opening size and the size of the through-hole on the permeable breakwater are considered. Interval, which determines the upper and lower position limits of the opening.

The vertical baffle type permeable breakwater has holes in the lower part, and the upper part is wave-proof and anti-drift. There are no holes in a certain range below the still water surface. From the perspective of structural stability, holes are opened at intervals in the lower part. From the perspective of anti-drifting, the vertical baffle type is adopted. Floating objects should not be adsorbed or hooked to the breakwater. The height of the opening is below the still water surface. A sand barrier is set at the bottom of the breakwater to prevent the sediment on the seabed raised by waves from entering the tail water reservoir.

In order to prevent the floating objects outside the breakwater from entering the enclosed reservoir, and also prevent the bottom sediment from entering the reservoir, the position of the permeable hole is set at a certain depth underwater, not too shallow to prevent floating objects from passing through the flow with the waves The holes should not be too deep, so as to meet the breakwater arrangement type and minimum opening height required for anti-drifting and sand prevention.

The parameters of the through-holes determined in this step are mainly the number and width of the openings of the through-holes on the permeable breakwater with a length L. Since the length of the permeable breakwater is fixed, considering the strength of the dam itself, the permeable holes cannot be too dense, and the width of each hole cannot actually be too wide. The number and width of the permeable holes are actually determined by external factors. The height of the permeable hole has a certain selection range.

Step 5. Calculating the height of the through-hole: According to the maximum water intake or discharge Q of the power station, the length of the breakwater L, the limited flow velocity v of the water in the through-hole, the width of the opening B _s , and the opening interval D _s , the opening height B of the through-hole is calculated:

进而确定防波堤开孔高度。For the water intake or drainage flow under the installed capacity of the power plant, the relationship between it and the layout length of the breakwater, the opening interval, the width and height of the opening, and the flow rate of water entering and leaving the opening can be obtained

Then determine the height of the breakwater opening.

Step 6, model experiment: verify whether the transmitted wave height H _t behind the embankment satisfies the requirement H _t ≤ H _s through the wave physical model test. If the requirement is met, the structure type of the permeable breakwater can be determined; The opening width B _s or height B of the orifice, and judge whether the opening scale exceeds the limit range, if it exceeds the limit range, add one or more rows of permeable breakwaters after the current breakwater to meet the transmitted wave height behind the embankment of the lower reservoir H _t ≤ H _s requirements.

After calculating the preliminary design scheme, a reduced enclosure model of the lower reservoir of the seawater pumped storage power station is built according to this design scheme, and the model test is conducted to verify that the wave height requirements behind the embankment are met under the conditions of incident waves and opening heights in front of the embankment. Rows of breakwaters. Since the width and height of the permeable hole are limited, they cannot be expanded without limit. When the width of the permeable hole increases, the structural stability requirements may not be met. When the height of the permeable hole reaches the limit, the permeable hole cannot be enlarged. It is necessary to increase the number of rows of permeable breakwaters, that is, add a row of permeable breakwaters. If the requirements are still not met, then continue to add another row of permeable breakwaters until the requirements of transmitted wave height H _t ≤ H _s behind the embankment are met.

Application examples:

The permeable breakwater should play a role in protecting the tail water of the lower reservoir of the seawater pumped storage power station. At the same time, comprehensively propose the protection of the tail water of the lower reservoir of the seawater pumped storage power station from the aspects of wave prevention, flow through, sand prevention, drift prevention and easy cleaning. Basic requirements for breakwater structures.

Under the planned installed capacity of a seawater pumped storage power station, the maximum drainage flow Q is 24m ³ /s, and the water depth in front of the permeable breakwater is d=5m. According to the terrain conditions, the breakwater can be arranged with a length L of about 100m. From the perspective of anti-drifting, the permeable breakwater should adopt the vertical baffle type, and the floating objects should not be adsorbed or linked to the breakwater, and the height of the floating objects should not be less than 2m below the still water surface; the sand-blocking sill should be set at the bottom of the breakwater, and its height should not be less than 0.5 m.

Based on the data of hydrology and planktonic characteristics of the sea area near the planned power plant, it is obtained that the flow rate v≤0.3m/s of the perforated water body is not easy to entrain floating objects to the permeable holes of the breakwater and the sea organisms can break free.

According to the fact that the height of the upper entity of the breakwater retaining floating objects should not be less than 2m below the still water surface, and the height of the sand-retaining sill at the bottom of the breakwater should not be less than 0.5m, it can be calculated that the height of the permeable section of the breakwater is between 0.5m above the water bottom and 2m below the still water surface within the range of 2.5m.

The hole width is 2m, and the distance between the holes is 1.5 times the hole width, that is, 3m; according to the intake/drainage flow Q of the power plant, the length L of the breakwater, and the limited flow velocity v of the through hole, the opening height B of the lower part of the permeable embankment is obtained:

Preliminary determination of breakwater opening height B = 2m.

According to the water level fluctuation requirements for the safe and stable operation of the power plant unit, the wave height H _s = 0.5m behind the permeable breakwater in the lower reservoir is obtained.

Breakwaters are arranged at an angle of 90 degrees to the incident direction of waves in the open sea, that is, the waves are incident directly on the permeable dike. According to the incident wave conditions in front of the embankment, the height and spacing of openings, a wave physical model is constructed. The transmitted wave height H _t behind the embankment is obtained through the physical model test. If H _t ≤ H _s =0.5m, the permeable embankment structure _{meets the} requirements; One or more rows of permeable breakwaters will be added later to meet the requirement of transmitted wave height H _t ≤ _{H s} =0.5m behind the embankment of the lower reservoir.

Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention without limitation, although the present invention has been described in detail with reference to the preferred arrangement scheme, those of ordinary skill in the art should understand that the technical solution of the present invention (such as The use of various formulas, the sequence of steps, etc.) are modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (1)

1. A design method for the tail water enclosure of the lower reservoir of a seawater pumped storage power station, the tail water enclosure is at least one row of vertical baffle type permeable breakwaters, and the lower part of the permeable breakwaters is provided with several rectangular permeable breakwaters. A flow hole, the section from the lower edge of the through-flow hole to the bottom of the breakwater is provided with a sill, and it is characterized in that the specific steps of the method are as follows: Step 1, analyze the requirements of permeable breakwaters: analyze the functional requirements of permeable breakwaters, and put forward the basic requirements of the permeable breakwater structures from the aspects of wave prevention, flow through, sand prevention, drift prevention and easy cleaning; Step 2, determine the basic parameters of the breakwater: obtain the planned installed capacity of the power station, thereby determine the maximum intake or drainage flow Q under the planned installed capacity, and investigate the conditions of the sea area where the power station is located, including terrain and geographical location, so as to obtain the permeable breakwater The length L and the water depth d in front of the permeable breakwater; for different environmental flow conditions, according to the water level fluctuation requirements for the safe and stable operation of the power plant unit, the allowable wave height H _s behind the permeable breakwater is obtained; Step 3. Obtain the limited flow rate of the water body of the through-hole: By investigating the hydrology and planktonic characteristics of the sea area where the power station is located, and considering the impact on the water environment in the surrounding sea area, it is obtained that the entrainment of floating objects to the through-hole and the potential for marine organisms are not easy to occur. The free through-hole water body restricts the flow velocity v; Step 4, obtain the parameters of the through-hole: According to the requirements of the reservoir to prevent floating objects and sand-retaining, and from the aspects of easy cleaning in the later stage, stable structure, strength, flow rate requirements of the through hole and drainage flow rate requirements, the opening size and the size of the through-hole on the permeable breakwater are considered. Interval, to determine the upper and lower position limits of the opening; Step 5. Calculating the height of the through-hole: According to the maximum water intake or discharge Q of the power station, the length of the breakwater L, the limited flow velocity v of the water in the through-hole, the width of the opening B _s , and the opening interval D _s , the opening height B of the through-hole is calculated:

Step 6, model experiment: Verify whether the transmitted wave height H _t behind the embankment meets the requirement H _t ≤ H _s through the wave physical model test. If the requirement is met, the structural type of the permeable breakwater can be determined; Orifice opening width or height B, and judge whether the opening scale exceeds the limit range, if it exceeds the limit range, add one or more rows of permeable breakwaters after the current breakwater to meet the transmission wave height H _t behind the reservoir embankment ≤H _s requirements.

Images