A method and system for calculating downstream water level under unsteady flow based on full response

Abstract

The application belongs to the technical field of reservoir regulation, and discloses a non-constant flow downstream water level calculation method and system based on full response, wherein the method comprises the following steps: determining flow jump time and corresponding jump flow change in the regulation period according to the flow change process in the regulation period, and dividing the regulation period into multiple jump periods based on the flow jump time; regarding the dynamic change process of the downstream water level as a full response process for any jump period, and constructing a downstream water level dynamic response model based on full response; and obtaining real-time downstream water level in any jump period by using the downstream water level dynamic response model. The application regards the downstream water level dynamic process under the non-constant flow condition as a full response by learning from the analysis method of system response in the circuit theory, and constructs a brand-new, simple-to-calculate analytical model for the calculation of hydraulics, which is beneficial to improving the accuracy and reliability of the non-constant flow downstream water level calculation while ensuring the simplicity of the calculation.

Description

Technical Field

[0001] This invention belongs to the technical field of reservoir scheduling, and more specifically, relates to a method and system for calculating downstream water level based on full response non-steady flow. Background Technology

[0002] In the optimized scheduling and actual operation of hydropower stations, the downstream water level is crucial, directly affecting the station's head and consequently, its power generation and efficiency. Traditionally, the downstream water level is estimated using a pre-determined water level-flow curve (i.e., the ZQ curve). However, the ZQ curve describes a steady state under constant, uniform flow conditions, assuming a stable downstream water level formed after a certain flow rate has been maintained for a sufficiently long time. In actual scheduling, the outflow from the hydropower station is a non-steady flow that frequently changes to meet grid load demands. The downstream water level often does not have enough time to reach a steady state. Using a stable ZQ curve for calculation in this situation would introduce significant errors, affecting the accuracy of scheduling decisions.

[0003] To accurately calculate water levels under unsteady flow conditions, the academic community has developed hydrodynamic models based on the Saint-Venant equations. While these models are highly accurate, their modeling process is complex and computationally intensive, making them difficult to directly embed into real-time optimization and scheduling models that require rapid decision-making. Therefore, finding a downstream water level calculation method that can both reflect the dynamic characteristics of unsteady flow and is computationally simple and fast has significant theoretical value and promising engineering application prospects. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method and system for calculating downstream water levels in unsteady flow based on full response. This method solves the problems of existing methods for calculating downstream water levels in unsteady flow being complex in modeling, computationally intensive, and difficult to directly embed into real-time optimization and scheduling models that require rapid decision-making. The aim is to improve the accuracy and reliability of downstream water level calculation in unsteady flow while ensuring computational simplicity.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for calculating downstream water level based on a nonsteady flow with full response is provided, comprising: S1. Based on the flow change process during the scheduling period, determine the flow jump time and the corresponding jump flow change during the scheduling period, and divide the scheduling period into multiple jump time periods based on the flow jump time. S2, For any jump period, the dynamic change process of the downstream water level is regarded as a full response process, and a downstream water level dynamic response model based on the full response is constructed. The real-time downstream water level in any jump period is obtained using the downstream water level dynamic response model.

[0006] According to the downstream water level calculation method based on full response nonsteady flow provided by the present invention, S2 specifically includes: For any jump period, the dynamic change process of the downstream water level is regarded as a full response process consisting of two linearly superimposed parts: zero-input response and zero-state response. The zero-input response is determined by the initial water level of the jump period and represents the natural decay process driven only by the initial state when there is no flow input. The zero-state response is determined by the stable downstream water level corresponding to the flow during the jump period and represents the response to flow input when the initial state is zero.

[0007] The downstream water level calculation method based on full response unsteady flow provided by the present invention further includes: S3. Establish a recursive calculation model for downstream water levels. For multiple flow jumps during the scheduling period, a recursive calculation strategy is adopted. Based on the downstream water level dynamic response model described in S2, starting from the initial moment of the scheduling period, the real-time downstream water level of the first jump period is calculated first, and the downstream water level corresponding to the end of the jump period is obtained based on the real-time downstream water level. When the next flow jump occurs, the downstream water level corresponding to the end of the previous jump period is used as the initial water level for the next jump period calculation. The calculation of S2 is repeated until the downstream water levels of all jump periods during the scheduling period are obtained.

[0008] According to the non-steady flow downstream water level calculation method based on full response provided by the present invention, for the first jump period, a zero input response is obtained according to the preset initial water level of the scheduling period, and a zero state response is obtained according to the stable downstream water level of the flow corresponding to the first jump period, thereby obtaining the real-time downstream water level of the first jump period.

[0009] The downstream water level calculation method based on full response of the unsteady flow provided by the present invention is based on the initial water level. Zero-input response of the decision The calculation formula is as follows: ; in, The current moment; This is the moment when traffic changes dramatically; for The initial water level at that moment; This serves as the baseline value for calculating downstream water levels. The time constant characterizing the river channel response.

[0010] According to the downstream water level calculation method based on full response of unsteady flow provided by the present invention, in A single traffic jump occurs at any time, and the traffic after the jump is The traffic corresponding to the jump period is then determined. Stable downstream water level Zero-state response of the decision The calculation formula is as follows: ; in, The current moment; This is the moment when traffic changes dramatically; This serves as the baseline value for calculating downstream water levels. The time constant characterizing the river channel response.

[0011] The downstream water level calculation method based on unsteady flow according to the present invention linearly superimposes the zero-input response and the zero-state response to obtain... time Real-time downstream water level The full response model is as follows: ; in, , These are the times when there are two consecutive flow rate jumps; This serves as the baseline value for calculating downstream water levels. A response with zero input; The response is a zero-state response.

[0012] According to the downstream water level calculation method based on full response unsteady flow provided by the present invention, the stable downstream water level corresponding to the flow rate during the jump period is obtained based on a pre-established stable water level-flow rate relationship curve; the downstream water level calculation reference value... The lowest riverbed elevation in the downstream channel was selected as the reference benchmark.

[0013] The downstream water level calculation method based on full response nonsteady flow provided by the present invention provides a real-time downstream water level calculation method. The following constraints must be satisfied during the acquisition process: Water level constraints: , Represents the lowest riverbed elevation in the downstream channel. This represents the upper limit of the downstream river channel water level; Traffic jump timing constraints: , and This represents the moment when there are two consecutive flow rate jumps.

[0014] According to another aspect of the present invention, a downstream water level calculation system based on a non-steady flow with full response is provided. The system includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the optimized scheduling method for the hydro-wind-solar hybrid system described above.

[0015] In summary, compared with the prior art, the technical solutions conceived in this invention provide a superior method and system for calculating downstream water levels based on fully responsive, unsteady flow: 1. This invention draws on the analysis methods of system response in circuit theory, approximating the non-steady flow process during the reservoir scheduling period as a series of step-change flow processes occurring at multiple jump moments. It regards the downstream water level dynamic process under non-steady flow conditions as a full response, and constructs and solves the downstream water level dynamic response model based on the full response. This provides a new and computationally simple analytical model for hydraulic calculations, which helps to improve the accuracy and reliability of downstream water level calculations under non-steady flow conditions while ensuring computational simplicity. It is suitable for scenarios that require rapid decision-making and real-time optimization scheduling. 2. The full response is decomposed into a linear superposition of zero-input response and zero-state response, which fully considers the influence of the initial water level during the jump period and the stable downstream water level of the corresponding flow during the jump period, and can accurately reflect the dynamic change process of the downstream water level. Furthermore, a recursive calculation model is proposed, which can solve any complex non-steady flow process consisting of a series of step flow rates through the recursive method of this invention, and has strong versatility and scalability. 3. Compared with the traditional steady ZQ relationship curve method, this invention fully considers the dynamic process of water level change and the influence of the initial state, which can significantly improve the accuracy of water level calculation under unsteady flow and is more in line with physical reality; 4. Compared with complex hydrodynamic models, this invention uses analytical expressions, which do not require complex numerical iterations in the calculation process. It is fast, consumes few resources, and is particularly suitable for scenarios such as real-time optimization and scheduling of reservoirs that require rapid and repeated calculations. Attached Figure Description

[0016] Figure 1 This is a flowchart of the downstream water level calculation method based on full response nonsteady flow provided in the embodiments of the present invention.

[0017] Figure 2 This is a complete flowchart of a non-steady flow downstream water level calculation method based on full response, constructed according to a preferred embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0019] Please see Figure 1This embodiment provides a method for calculating downstream water level in unsteady flow based on full response. This method includes: S1. Based on the flow change process during the scheduling period, determine the flow jump time and the corresponding jump flow change during the scheduling period, and divide the scheduling period into multiple jump time periods based on the flow jump time. S2, For any jump period, the dynamic change process of the downstream water level is regarded as a full response process, and a downstream water level dynamic response model based on the full response is constructed. The real-time downstream water level in any jump period is obtained using the downstream water level dynamic response model.

[0020] In some embodiments, S2 specifically includes: For any jump period, the dynamic change process of the downstream water level is regarded as a full response process consisting of two linearly superimposed parts: zero-input response and zero-state response. The zero-input response is determined by the initial water level of the jump period and represents the natural decay process driven only by the initial state when there is no flow input. The zero-state response is determined by the stable downstream water level corresponding to the flow during the jump period and represents the response to flow input when the initial state is zero.

[0021] In some embodiments, the method for calculating downstream water levels in non-steady flow further includes: S3 establishes a recursive calculation model for downstream water levels. For multiple flow jumps during the scheduling period, a recursive calculation strategy is adopted. Based on the downstream water level dynamic response model described in S2, starting from the initial moment of the scheduling period, the real-time downstream water level for the first jump period is calculated, and the downstream water level at the end of the jump period is obtained based on the real-time downstream water level. When the next flow jump occurs, the downstream water level at the end of the previous jump period is used as the initial water level for the next jump period calculation, and the calculation in S2 is repeated until the downstream water levels for all jump periods within the scheduling period are obtained. That is, starting from the initial moment of the scheduling, the initial moment is also considered as a flow jump, and the dynamic change process of the downstream water level after each flow jump is calculated sequentially, with the previous jump period starting from the jump moment. arrive End of period The water level is used as the initial water level for the next jump time period until the downstream water level at all times during the scheduling period is obtained.

[0022] In some embodiments, for the first transition period, which is the period from the initial time to the first flow transition time within the scheduling period, a zero input response is obtained based on the preset initial water level of the scheduling period, and a zero state response is obtained based on the stable downstream water level of the flow corresponding to the first transition period, thereby obtaining the real-time downstream water level of the first transition period.

[0023] In some embodiments, the initial water level Zero-input response of the decision The calculation formula is as follows: ; in, The current moment; This is the moment when traffic changes dramatically; for The water level at that moment is to The initial water level for the specified time period; This serves as the baseline value for calculating downstream water levels. The time constant characterizing the river channel response.

[0024] In some embodiments, A single traffic jump occurs at any time, and the traffic after the jump is The traffic corresponding to the jump period is then determined. Stable downstream water level Zero-state response of the decision The calculation formula is as follows: ; in, The current moment; This is the moment when traffic changes dramatically; This serves as the baseline value for calculating downstream water levels. The time constant characterizing the river channel response. for The corresponding stable downstream water level.

[0025] In some embodiments, the zero-input response and the zero-state response are linearly superimposed to obtain time Real-time downstream water level The full response model is as follows: ; in, , These are the times when there are two consecutive flow rate jumps; This serves as the baseline value for calculating downstream water levels. A response with zero input; The response is a zero-state response.

[0026] Specifically, this embodiment approximates the non-constant flow process during the reservoir scheduling period as occurring at multiple jump moments. A series of step-change flow processes occur. This is the moment when traffic changes dramatically; k It can represent the sequence number of traffic jumps. n This indicates the total number of traffic jumps. k Take 0- n ;exist kWhen the value is 0, This corresponds to the initial moment of the scheduling period; k Take 1- n hour, The first one in the corresponding scheduling period k At the moment of the next traffic jump, The flow rate at any time is determined by jump to .

[0027] The recursive calculation model for downstream water level in S3 is established according to the following method: Initialization: Set the transition period counter , corresponding to the That is, the first transition period ; Determine the transition period input: For the first... A transition period (from the transition time) arrive First, it is necessary to determine its initial water level. , The method for determining this varies depending on the transition period: when hour, It is taken directly from the initial water level set for the scheduling period; when hour, The water level at the end of the calculated time period is then used to determine the water level. Then obtain the traffic during that transition period. Corresponding stable downstream water level ; Based on the downstream water level dynamic response model established in S2, the dynamic response model at any time during this jump period is established. Real-time downstream water level The calculation formula is the downstream water level model: ; Calculate the water level at the end of the time period using the above relationship: Based on the downstream water level model, let... Calculate the end of the transition period water level ; Update and Iteration: Determine if the calculation for all time periods of the scheduling period has been completed. If not, obtain the water level at the end of each time period. As the initial water level for the next jump transition period, then let Return to the input steps for confirming the transition period; if yes, the calculation ends.

[0028] In some embodiments, the stable downstream water level corresponding to the flow rate during the jump period. Based on a pre-established steady-state water level-discharge relationship curve The relationship curve is the stable water level relationship under a stable flow rate. It can be obtained through simulation and other methods. The specific methods are quite conventional and will not be elaborated here.

[0029] Downstream water level calculation benchmark The lowest riverbed elevation in the downstream channel can be selected as a reference benchmark. Before S2, the initial conditions for the reservoir operation period must be set; these initial conditions refer to the initial water level at the beginning of the operation period; the initial conditions may also include constraint conditions.

[0030] In some embodiments, real-time downstream water level The following constraints must be satisfied during the acquisition process: Water level constraints: , Represents the lowest riverbed elevation in the downstream channel. This represents the upper limit of the downstream river channel water level; Traffic jump timing constraints: , and This represents the moment when there are two consecutive flow rate jumps.

[0031] In some embodiments, the time constant characterizing the channel response characteristics in the downstream water level dynamic response model based on the full response is... The following method was used to determine the downstream water level process of the hydropower station, assuming the flow rate was... Time by jump to , Flow retention after time constant, The corresponding stable downstream water level is Measured through experiments Any two time points after time point and The measured downstream water level is and Time constant The calculation formula is: .

[0032] In some embodiments, the initial water level The determination varies depending on the transition period: for the first transition period Corresponding to the jump time arrive Its initial water level The global initial water level is directly taken from the entire scheduling period, which can be the actual water level at the beginning of the scheduling period; for the second transition period... Its initial water level The water level is determined by the water level at the end of the previous transition period, which reflects the recursive relationship of the water level status over time.

[0033] In some embodiments, a downstream water level calculation system based on full response non-steady flow is also provided. The system includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to perform the optimized scheduling method for the hydro-wind-solar hybrid system described above.

[0034] In some specific embodiments, this embodiment provides a method for calculating downstream water level based on a non-steady flow with full response. Taking a hydropower station as an example, the specific steps include: The following parameters are known to be obtained through calibration using historical data: river channel response time constant. =12h; the stable water level-discharge relationship curve is as follows: =0.00000003 + 0.0008 +28.2659; Lowest riverbed elevation in the downstream channel =27.8m; Step 1: Set the initial conditions during the reservoir operation period: The scheduling period is 24 hours, and the initial water level during the scheduling period is... When =0, =28.5m. Flow rate jump moment: at =6h, flow rate from m 3 / s jump becomes m 3 / s; in =18h, flow rate from m 3 / s jump becomes m 3 / s. Initial water level during the scheduling period. Meeting water level constraints; jump moment This satisfies the constraint of the timing of traffic jumps.

[0035] Step 2: Construct a dynamic response model for downstream water levels based on the full response.

[0036] Step 3 establishes a recursive calculation model for the downstream water level. This includes the following sub-steps: Initialization: Set the transition period counter Determine the input for the first transition period (0-6h) (first loop) =0): when At that time, the initial water level This is the initial water level during the scheduling period. =28.5m; assumed At that time, the flow rate changed from an unknown stable state to... m 3 / s, then the stable downstream water level corresponding to the flow rate during this transition period is = =0.00000003×1000 2 + 0.0008×1000 +28.2659 = 29.096m; Based on step 2, establish the transition period. at any time Downstream water level model: =27.8+(28.5-27.8) +(29.096-27.8) ; calculate Water level at 6: =27.8+(28.5-27.8) +(29.096-27.8) =28.734m.

[0037] At this point, the calculations for all time periods of the scheduling period have not been completed, and... =28.734m is used as the initial water level for the next jump period, and the calculation continues. Let Repeat step 3 (second cycle) ): Determine the input for the second transition period (6-18h). when At that time, the initial water level This refers to the water level at the end of the previous transition period, calculated as follows: =28.734m; When =6, the flow rate is from m 3 / s jump becomes m 3 / s, then the stable downstream water level corresponding to the flow rate during this transition period is = =0.00000003×2800 2 + 0.0008×2800 + 28.2659= 30.741m; Based on step 2, establish the transition period. at any time Downstream water level model: =27.8+(28.734-27.8) +(30.741-27.8) ; calculate Water level at 18: =27.8+(28.734-27.8) +(30.741-27.8) =30.003m.

[0038] At this point, the calculations for all time periods of the scheduling period have not been completed, and... =30.003m is used as the initial water level for the next jump time period, and the calculation continues. Let Repeat step 3 (third cycle) ): Determine the input for the third transition period (18-24h). when At that time, the initial water level This refers to the water level at the end of the previous transition period, calculated as follows: =30.003m; When =18, the flow rate is from m 3 / s jump becomes m 3 / s, then the stable downstream water level corresponding to the flow rate during this transition period is = =0.00000003×1200 2 + 0.0008×1200 +28.2659 = 29.269m; Based on step 2, establish the transition period. at any time Downstream water level model: =27.8+(30.003-27.8) +(29.269-27.8)

[0039] calculate Water level at 24: =27.8+(30.003-27.8) +(29.269-27.8) =29.462m; At this point, the calculations for all time periods of the scheduling period have been completed, and the loop ends.

[0040] By following the steps above, the precise downstream water level process at any point during the entire scheduling period can be obtained.

[0041] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating downstream water level based on unsteady flow with full response, characterized in that, include: S1. Based on the flow change process during the scheduling period, determine the flow jump time and the corresponding jump flow change during the scheduling period, and divide the scheduling period into multiple jump time periods based on the flow jump time. S2, For any jump time period, the dynamic change process of the downstream water level is regarded as a full response process, and a downstream water level dynamic response model based on the full response is constructed. The real-time downstream water level in any jump time period is obtained using the downstream water level dynamic response model. S2 specifically includes: For any jump period, the dynamic change process of the downstream water level is regarded as a full response process consisting of two linearly superimposed parts: zero-input response and zero-state response. The zero-input response is determined by the initial water level of the jump period, representing the natural decay process driven only by the initial state when there is no flow input. The zero-state response is determined by the stable downstream water level corresponding to the flow during the jump period, representing the response to flow input when the initial state is zero. From the initial water level Zero-input response of the decision The calculation formula is as follows: ； in, The current moment; This is the moment when traffic changes dramatically; for The initial water level at that moment; This serves as the baseline value for calculating downstream water levels. The time constant characterizing the river channel response; exist A single traffic jump occurs at any time, and the traffic after the jump is The traffic corresponding to the jump period is then determined. Stable downstream water level Zero-state response of the decision The calculation formula is as follows: ； in, The current moment; This is the moment when traffic changes dramatically; This serves as the baseline value for calculating downstream water levels. The time constant is used to characterize the response characteristics of the river channel.

2. The downstream water level calculation method based on a nonsteady flow with full response as described in claim 1, characterized in that, Also includes: S3, Establish a recursive calculation model for downstream water level; For multiple flow jumps during the scheduling period, a recursive calculation strategy is adopted. Based on the downstream water level dynamic response model described in S2, starting from the initial moment of the scheduling period, the real-time downstream water level of the first jump period is calculated first, and the downstream water level corresponding to the end of the jump period is obtained based on the real-time downstream water level. When the next flow jump occurs, the downstream water level corresponding to the end of the previous jump period is used as the initial water level for the next jump period calculation, and the calculation in S2 is repeated until the downstream water levels of all jump periods during the scheduling period are obtained.

3. The downstream water level calculation method based on a non-steady flow with full response as described in claim 2, characterized in that, For the first transition period, a zero-input response is obtained based on the preset initial water level of the scheduling period, and a zero-state response is obtained based on the stable downstream water level of the flow corresponding to the first transition period, thereby obtaining the real-time downstream water level of the first transition period.

4. The downstream water level calculation method based on a nonsteady flow with full response as described in claim 1, characterized in that, By linearly superimposing the zero-input response and the zero-state response, we obtain... time Real-time downstream water level The full response model is as follows: ； in, , These are the times when there are two consecutive flow rate jumps; This serves as the baseline value for calculating downstream water levels. A response with zero input; The response is a zero-state response.

5. The downstream water level calculation method based on a non-steady flow with full response as described in claim 4, characterized in that, The stable downstream water level corresponding to the flow rate jump period is obtained based on a pre-established stable water level-flow rate relationship curve; the downstream water level calculation benchmark value. The lowest riverbed elevation in the downstream channel was selected as the reference benchmark.

6. The downstream water level calculation method based on a nonsteady flow with full response as described in claim 1, characterized in that, Real-time downstream water level The following constraints must be satisfied during the acquisition process: Water level constraints: , Represents the lowest riverbed elevation in the downstream channel. This represents the upper limit of the downstream river channel water level; Traffic jump timing constraints: , and This represents the moment when there are two consecutive flow rate jumps.

7. A downstream water level calculation system based on a nonsteady flow with full response, characterized in that, The system includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it performs the downstream water level calculation method based on full response non-steady flow as described in any one of claims 1-6.

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