Cascade avionics hub accurate operation scheduling method considering flood propagation time delay and tanning effect

Abstract

The invention provides a cascade avionics hub accurate operation scheduling method considering flood propagation time lag and a tanning effect, and the method comprises the steps: building a hydrodynamic model of a river channel between cascade hubs based on the warehouse-out flow of a superior hub A and the gate-front water level boundary condition of a current hub B; the upstream boundary condition and the downstream boundary condition of the hydrodynamic model are obtained through real-time monitoring, and the hydrodynamic model is solved to obtain the pre-sluice flow of the hub B; calculating the discharged flow of the hub B according to the pre-sluice flow of the hub B; according to the discharged flow of the hub B, based on the water level-flow-gate opening curve of the hub B, the opening degree of a water discharge gate of the hub B is obtained, and therefore operation scheduling of the gate is automatically controlled; and repeating the steps 1-5 to realize the real-time scheduling of the gate at each time step in the flood discharge process. The method can accurately predict the action of the lower-level gate, ensures that the water level amplitude in front of the gate is within a certain range, and prevents the unit output from being influenced by upstream water level fluctuation to reduce the operation efficiency and stability of the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of flood control dispatching of cascade navigation and power hubs, and specifically to a precise operation dispatching method of cascade navigation and power hubs taking into account flood propagation time lag and tanking effect. Background Art

[0002] When the cascaded navigation and power hub is in operation and dispatch, the outbound flow Q of each hub is 出 The statistical method is flood discharge Q 泄 With the power generation flow Q 电 The sum of the power generation flow Q 电 Generally, it is calculated according to the relevant formula based on the water level difference between the upstream and downstream of the hub or interpolated based on the NHQ curve of the unit; the flood discharge Q 泄 The gate discharge curve integrated in the water regulation system is used for interpolation calculation. 入 It is also necessary to use the reservoir capacity curve to obtain the flow rate Q to fill or reduce the reservoir capacity according to the change of the reservoir water level per unit time. 库 , and then combine the hub outbound flow to get the hub inbound flow Q 入 , i.e. Q 入 =Q 电 +Q 泄 +Q 库 (Define Q 入 It is the flow rate before the hub gate, also known as the flow rate before the gate).

[0003] However, during the operation of hub dispatching at all levels, it was found that the hub inflow flow Q obtained by reverse calculation of the relevant curves of the water diversion system during the flood discharge operation was 入 The outbound flow Q reported by the upper-level hub 出 There are deviations, and the flow mismatch between the upstream and downstream cascades leads to an imbalance in the amount of water. For example, in the invention patent 202311426564.7 (a method and device for dispatching and operating gates of water transfer projects), in the water transfer channel, the difference in the flow through the upstream gate at two moments before and after is used as the correction parameter for the opening of the downstream gate to calculate the opening of the downstream gate. If the channel is long, there will be a problem of inequality between the outflow of the upper gate and the inflow of the lower gate. In a cascade reservoir, if a hub at a certain level controls the outflow flow through the discharge curve of the hub at this level based on the sum of the outflow flow of the hub at the previous level + the inflow flow of the tributaries along the way, the inaccurate outflow flow will cause the water level in front of the gate to fail to maintain stability or fail to change according to the expected trend; if the hub dispatches the opening of the sluice gate in accordance with maintaining the water level in front of the gate unchanged, the outflow flow calculated by the system according to the design discharge curve will not match the size of the upstream inflow. Therefore, when there is a large deviation in the flow between the upstream and downstream levels, the final inflow and outflow flow data reported to the system is usually manually corrected by on-site operation management personnel, but the rationality of the correction results remains to be verified.

[0004] During the flood season, the dispatching methods of different cascades are different, the flow rates used for power generation vary, and the opening time of the sluice gates varies. This causes the entire basin to be in a non-steady flow process with constantly changing boundary conditions, making it difficult to achieve a stable equilibrium state. In particular, the two hubs are relatively far apart, and it takes a certain amount of time for the flood water from the upper hub to propagate to the dam of the current hub. Figure 1 As shown in the figure, due to the time lag effect of flood propagation and the flood flattening effect, the outflow flood from the upper hub takes a certain amount of time to reach hub B, which is the time lag effect of flood propagation. In addition, due to the attenuation characteristics of flood propagation, which is the flattening effect of flood propagation, the outflow flow of the upper hub is not always equal to the flow before the gate of the lower hub. When operating and dispatching, the lower hub cannot simply dispatch the real-time outflow flow of the upper hub as the inflow or gate flow of the hub at this level, so as to avoid scheduling errors caused by inaccurate incoming flow. For example, if the gate is opened before the flood reaches hub B, causing over-discharge, or if the flood has arrived but the gate is not opened in time, causing the water level before the gate to be too high, it will affect the project benefits and safe operation. Therefore, when operating and dispatching cascade reservoirs, it is also necessary to consider the time lag effect of flood propagation between cascade hubs and the alienation and deformation of flow during flood evolution. Summary of the invention

[0005] In order to solve the problem that the outflow flow of the upper-level hub and the flow before the gate of the current-level hub deviate during the operation and scheduling of the cascade navigation and power hub, resulting in the inability to accurately schedule the current-level hub, the present invention provides a precise operation and scheduling method for cascade navigation and power hubs considering the flood propagation time lag and the tanking effect, establishes a hydrodynamic model of the river between the cascade hubs, calculates the flow before the lower-level gate under the upper-level outflow flow in real time, and couples it with the gate automatic control operation and scheduling system, with the goal of small water level fluctuation before the gate and less gate action times, accurately predicts the action of the lower-level gate, ensures that the water level fluctuation before the gate is within a certain range, and avoids the unit output being affected by the upstream water level fluctuation, thereby reducing the efficiency and stability of the unit operation.

[0006] The specific scheduling steps of the present invention are as follows:

[0007] A method for precise operation and dispatching of cascade navigation and power hubs considering flood propagation time lag and tanking effect, characterized in that it comprises the following steps:

[0008] Step 1: Construct a hydrodynamic model of the river between cascade hubs A and B;

[0009] Step 2: monitor and obtain the real-time boundary conditions of the hydrodynamic model, including the outflow boundary of the upper-level hub A and the water level boundary before the gate of the current-level hub B;

[0010] Step 3: Solve the hydrodynamic model to obtain the flow before the gate of hub B;

[0011] Step 4: Calculate the outflow of hub B based on the flow before the gate of hub B;

[0012] Step 5: According to the downstream flow of hub B and the water level-flow-gate opening curve of hub B, the opening of the hub B sluice gate is obtained, so as to automatically control the gate operation scheduling;

[0013] Step 6: Repeat steps 1 to 5 to achieve real-time gate scheduling at each time step during the flood discharge process.

[0014] Furthermore, in step 1, the hydrodynamic model includes a continuity equation and a momentum equation, which are as follows:

[0015] Continuity equation:

[0016]

[0017] Momentum equation:

[0018]

[0019] Where x, y, z are Cartesian coordinate systems; t is time; η is the riverbed elevation; d is the still water depth; h = η + d is the total water depth; u and v are the velocity components in the x and y directions, respectively; is the average velocity based on water depth; g is the acceleration due to gravity; ρ is the density of water, ρ0 is the reference density of water; p a is atmospheric pressure; S xx ,S xy ,S yx ,S yy is the component of the radiation stress tensor in each direction; S is the flow rate generated by the source and sink term, and the flow rate from the point source into the surrounding water body is expressed as (u s ,v s );T ij is the lateral stress term, which includes viscous friction, turbulent friction, and differential advection.

[0020] Furthermore, in step 2, the upstream boundary condition of the hydrodynamic model is the outflow flow Q provided by hub A in real time. A (t) Change process, the outbound flow Q of hub A A (t) According to its water level-flow-gate opening curve, the flow rate of hub A is obtained at each time step by using the known gate opening and the upstream and downstream water levels, and is assigned to the hydrodynamic model as its upstream calculation boundary condition;

[0021] The downstream boundary condition of the hydrodynamic model is the real-time monitored water level H in front of the hub B gate. B0 (t).

[0022] Furthermore, the water level before the hub B gate is H B0 (t) Real-time monitoring is performed using a submersible liquid level transmitter, which is placed 20 cm below the lowest upstream water level. The submersible water level transmitter is connected to a wireless acquisition and transmission module, which outputs the collected water level data to the user end and assigns it to the hydrodynamic model in real time as a downstream boundary condition.

[0023] Furthermore, step three specifically includes: using the finite volume method based on the unit center to solve the hydrodynamic model, obtain the velocity distribution of the entire model at each time step, and then integrate and output the real-time flow rate Q before the gate of hub B B入 (t).

[0024] Furthermore, step 4 specifically includes: according to the flow rate Q before the gate of hub B B入 (t) and power generation flow Q B电 (t), calculate the downstream flow Q of hub B B泄 (t):

[0025] Q B泄 (t) = Q B入 (t)-Q B电 (t).

[0026] Furthermore, the gate opening and closing rules of the hub B sluice gate in step 5 are:

[0027] The automatic control and dispatching of the gate of hub B is based on the water level H in front of the hub B gate. B0 (t) At target water level H z0 The water level in front of the gate exceeds H. z0 ±ΔH, the gate starts to move. When the water level in front of the gate is H B0 Greater than H z0 +ΔH opens the gate, H B0 Less than H z0 -ΔH, the gate is closed; the water level in front of the gate is H after the gate of hub B is actuated B0 The changes will update the H B0 The downstream boundary conditions assigned to the hydrodynamic model.

[0028] The present invention has the following beneficial effects: it takes into account the influence of the time lag and tanking effect of flood propagation between cascade navigation and power hubs on the flood discharge of the lower hubs, and through real-time coupling of the hydrodynamic model of the river between the hubs and the automatic control operation and dispatching system of the gates of the lower hubs, with the goal of small fluctuations in the water level in front of the hub gates and few gate actions, accurately predicts the actions of the lower gates, ensures that the fluctuations in the water level in front of the gates are within a certain range, and avoids the unit output being affected by the upstream water level fluctuations, thereby reducing the efficiency and stability of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the change process of the outflow flow of the upper hub and the flow before the gate of the lower hub under the time lag effect of flood propagation and flood flattening;

[0030] Figure 2 It is a flow chart of the cascade navigation and power hub dispatching method in each time step provided by the present invention;

[0031] Figure 3 It is a schematic diagram of coupling the hydrodynamic model of the river channel between the cascade hubs and the gate automatic control model;

[0032] Figure 4 is the flow variation along the cascade reservoir simulation area at the characteristic time;

[0033] Figure 5 It is a comparison chart of the outbound flow process of hub A and the flow process before the gate of hub B;

[0034] Figure 6 It is the water level-flow-opening curve of the spillway of hub B.

[0035] Figure 3 Middle: 1—Control gate of cascade hub A; 2—Control gate of cascade hub B; 3—Hydrodynamic model grid of the river channel between cascade hubs A and B; 4—Water level monitoring and automatic output system in front of the control gate of cascade hub B (immersion level transmitter and wireless acquisition and transmission module). DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] like Figure 2 As shown, the present invention discloses a precise operation and dispatching method for cascade navigation and power hubs considering flood propagation time lag and tanking effect, including a hydrodynamic model of the river between cascade hubs and a gate automatic control operation and dispatching system, realizing real-time coupling calculation of the two and providing calculation boundaries for each other. The specific implementation includes the following steps:

[0038] Step 1: Based on the outflow of the upper hub and the boundary conditions of the water level in front of the hub gate, a hydrodynamic model of the flow channel between the cascade hubs is constructed. Step 1 specifically includes:

[0039] like Figure 3As shown, a hydrodynamic model of the flow channel between hub A and hub B is established, namely a two-dimensional shallow water equation hydrodynamic model, and a numerical solution method is applied to solve it. The two-dimensional shallow water equation hydrodynamic model includes the continuity equation and the momentum equation, which are as follows:

[0040] Continuity equation:

[0041]

[0042] Momentum equation:

[0043]

[0044] Where x, y, z are Cartesian coordinate systems; t is time; η is the riverbed elevation; d is the still water depth; h = η + d is the total water depth; u and v are the velocity components in the x and y directions, respectively; is the average velocity based on water depth; g is the acceleration due to gravity; ρ is the density of water, ρ0 is the reference density of water; p a is atmospheric pressure; S xx ,S xy ,S yx ,S yy is the component of the radiation stress tensor in each direction; S is the flow rate generated by the source and sink term, and the flow rate from the point source into the surrounding water body is expressed as (u s ,v s );T ij is the lateral stress term, which includes viscous friction, turbulent friction, and differential advection.

[0045] Step 2: Obtain the upstream and downstream boundary conditions of the hydrodynamic model

[0046] The upstream boundary condition of the hydrodynamic model is the outflow flow Q of the upper hub A. A (t), which is obtained based on the water level-flow-gate opening curve of the A hub sluice gate, and the outflow flow Q at each time step is A (t) is assigned to the hydrodynamic model as the upstream boundary condition.

[0047] The downstream boundary condition of the hydrodynamic model is the real-time monitored water level H in front of the hub B gate. B0 (t). Water level H before the hub B gate B0 (t) Real-time monitoring is performed using a submersible liquid level transmitter, which is placed 20 cm below the lowest upstream water level. The submersible water level transmitter is connected to a wireless acquisition and transmission module, which outputs the collected water level data to the user end and assigns it to the hydrodynamic model in real time as a downstream boundary condition.

[0048] Step 3: Solve the hydrodynamic model to obtain the flow rate before the gate of hub B

[0049] The finite volume method based on the unit center is used to discretize the equations of the hydrodynamic model of the two-dimensional shallow water equation. In the Cartesian coordinate system, the two-dimensional shallow water equation can be expressed as:

[0050]

[0051] In the formula, I and V represent the inviscid flux and viscous flux respectively, and the specific expressions of each item are as follows:

[0052]

[0053] Then, using Gauss's theorem to integrate the equation, we get

[0054]

[0055] In the formula, A i The unit Ω i The area of ​​Ω is defined in A i The integral variable on Γ i is the boundary of the unit; ds is the integral variable on the boundary; is the unit vector of the outward normal on the boundary.

[0056] The general form of the time integral is:

[0057]

[0058] For two-dimensional simulation, the first-order explicit Euler method is used, then U n+1 =U n +ΔtG(U n ), where Δt is the solution time step.

[0059] The velocity distribution of the river channel between hubs A and B is obtained by solving. The entire hydrodynamic model is solved numerically. Through the equations and upstream and downstream boundary conditions, the velocity and water depth in the entire flow field are obtained, and then the flow distribution of the entire flow field is obtained. Specifically, the solution domain is divided by grids, and the shallow water equation is discretized based on the finite volume method. First, the physical quantities in the formula are discretized in triangular grids, and then the shallow water equation is rewritten into its discrete form using the finite volume method. In the discrete shallow water equation, the calculation of physical quantities such as water level and flow velocity can be converted into the calculation of flux terms on the grid interface and source terms within the grid. For the flux terms in the discrete equations, this model will use the Roe format based on the Riemann approximate solution to numerically solve the interface flux. For any control volume grid, the Gaussian divergence theorem is used to integrate the equation along the boundary line, and the time derivative term is discretized using the difference method to obtain a numerical solution. Before the calculation begins, the initial flow field needs to be given. The above solution is used to update the hydraulic variables from the current time step to the next moment. Similarly, the process of how the hydraulic variables in each calculation grid change over time is obtained.

[0060] like Figure 4 As shown in Figure 2, the inflow flow at hub B is monitored, such as Figure 5 As shown, it can be seen that there is a deviation between the outflow flow of hub A and the flow before the gate of hub B at each time step, and there is an obvious flattening deformation and time lag effect in the flood propagation between the cascades.

[0061] Step 4: Calculate the downstream flow of hub B based on the flow before the gate of hub B.

[0062] Specifically, according to the flow rate Q before the gate of hub B B入 (t), calculate the flow Q that hub B needs to discharge B泄 (t). In order to ensure the stability of the upstream water level of hub B, the flow rate that needs to be discharged is the flow rate before the gate Q B入 (t) minus the power generation flow Q of hub B B电 (t), i.e. Q B泄 (t) = Q B入 (t)-Q B电 (t).

[0063] Step 5: Based on the downstream flow Q of hub B B泄 (t), based on the water level-flow-gate opening curve of hub B, the opening of the hub B sluice gate is obtained, thereby automatically controlling the gate operation scheduling.

[0064] In order to ensure the safe operation of the hub and the efficiency and stability of the unit's power generation, the operating head in front of the gate cannot be too high, causing the water level to exceed the flood limit and affect the safety of flood discharge; on the other hand, it cannot be too low, causing water loss and affecting power generation efficiency. Therefore, when the flood reaches hub B, it is necessary to reasonably dispatch the gate to discharge the flood to ensure a small change in the water level in front of the gate. Since the flood process changes in real time, in order to avoid continuous operation of the gate, a step-by-step dispatching operation plan is adopted.

[0065] Water level H upstream of hub B B0 At the target water level H z0 When the upstream water level fluctuation range exceeds H z0 ±ΔH, the gate starts to move; when the upstream water level H B0 Greater than H z0 +ΔH opens the gate, when H B0 Less than H z0 -ΔH, close the gate. The gate opening of Hub B is automatically calculated by the gate water level-flow-gate opening relationship curve. The specific operation and dispatching rules are implemented based on the existing dispatching rules of the hub, such as Figure 6 As shown. The water level H in front of the gate caused by the operation of the hub B gate B0 The changes will update the H B0 The downstream boundary conditions assigned to the hydrodynamic model.

[0066] Step 6: Repeat steps 1 to 5 to achieve real-time gate dispatching at each time step during the flood discharge process. The water level H in front of the gate caused by the operation of the hub B gate B0 The changes will update the H B0 The downstream boundary conditions of the hydrodynamic model are assigned, and then the calculation process of steps 2 to 5 is repeated to achieve real-time coupling of the hydrodynamic model of the flow channel between the cascade hubs and the hub gate automatic control system.

[0067] The present invention discloses a precise operation and dispatching method of cascade navigation and power hubs considering the time lag and tundish effect of flood propagation, including a hydrodynamic model of the flow channel between cascade hubs and a gate automatic control operation and dispatching system, which provide calculation boundaries for each other to achieve real-time coupling and output. The advantages of the present invention are that the tundish and time lag effects of flood propagation between cascade reservoirs are considered, accurate flow before the gates of cascade reservoirs is obtained, and a scientific basis is provided for precise dispatching and operation of gates.

[0068] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A precise operation and dispatching method for cascade navigation and power hubs considering flood propagation time lag and tanking effect, characterized in that: The steps include: Step 1: Construct a hydrodynamic model of the river between cascade hubs A and B; Step 2: monitor and obtain the real-time boundary conditions of the hydrodynamic model, including the outflow boundary of the upper-level hub A and the water level boundary before the gate of the current-level hub B; Step 3: Solve the hydrodynamic model to obtain the flow before the gate of hub B; Step 4: Calculate the outflow of hub B based on the flow before the gate of hub B; Step 5: According to the downstream flow of hub B and the water level-flow-gate opening curve of hub B, the opening of the hub B sluice gate is obtained, so as to automatically control the gate operation scheduling; Step 6: Repeat steps 1 to 5 to achieve real-time gate scheduling at each time step during the flood discharge process.

2. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 1, characterized in that: In step 1, the hydrodynamic model includes the continuity equation and the momentum equation, which are as follows: Continuity equation: Momentum equation: Where x, y, z are Cartesian space coordinates; t is time; η is the riverbed elevation; d is the still water depth; h = η + d is the total water depth; u and v are the velocity components in the x and y directions respectively; is the average velocity based on water depth; g is the acceleration due to gravity; ρ is the density of water, ρ0 is the reference density of water; p a is atmospheric pressure; S xx ,S xy ,S yx ,S yy is the component of the radiation stress tensor in each direction; S is the flow rate generated by the source and sink term, and the flow rate from the point source into the surrounding water body is expressed as (u s ,v s );T ij is the lateral stress term, which includes viscous friction, turbulent friction, and differential advection.

3. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 1 or 2, characterized in that: In step 2, the upstream boundary condition of the hydrodynamic model is the outflow flow Q provided by hub A in real time. A (t) Change process, the outbound flow Q of hub A A (t) According to its water level-flow-gate opening curve, the flow rate of hub A is obtained at each time step by using the known gate opening and the upstream and downstream water levels, and is assigned to the hydrodynamic model as its upstream calculation boundary condition; The downstream boundary condition of the hydrodynamic model is the real-time monitored water level H in front of the hub B gate. B0 (t).

4. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 3, characterized in that: Water level H before the hub B gate B0 (t) Real-time monitoring is performed using a submersible liquid level transmitter, which is placed 20 cm below the lowest upstream water level. The submersible water level transmitter is connected to a wireless acquisition and transmission module, which outputs the collected water level data to the user end and assigns it to the hydrodynamic model in real time as a downstream boundary condition.

5. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 1, characterized in that: Step 3 specifically includes: using the finite volume method based on the unit center to solve the hydrodynamic model, obtain the velocity distribution of the entire model at each time step, and then integrate and output the real-time flow rate Q before the gate of hub B B入 (t).

6. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 1, characterized in that: Step 4 specifically includes: Based on the flow rate Q before the gate of hub B B入 (t) and power generation flow Q B电 (t), calculate the downstream flow Q of hub B B泄 (t): Q B泄 (t)=Q B入 (t)-Q B电 (t)。 7. The precise operation and dispatching method of cascade navigation and power hubs considering flood propagation time lag and tanking effect as claimed in claim 1, characterized in that: The gate opening and closing rules of the Hub B sluice gate in step 5 are: The automatic control and dispatching of the gate of hub B is based on the water level H in front of the hub B gate. B0 (t) At target water level H z0 The water level in front of the gate exceeds H. z0 ±ΔH, the gate starts to move. When the water level in front of the gate is H B0 Greater than H z0 +ΔH opens the gate, H B0 Less than H z0 -ΔH, the gate is closed; the water level in front of the gate is H after the gate of hub B is actuated B0 The changes will update the H B0 The downstream boundary conditions assigned to the hydrodynamic model.

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