Tidal shipping scheduling method for hydropower station under bias inflow condition

Abstract

The invention provides a tidal shipping scheduling method for a hydropower station under the condition of bias incoming water, and the method comprises the steps: building a one-dimensional hydrodynamic model through collecting the operation information of the hydropower station, a channel, a wharf and ship information, and deducing the minimum airworthiness flow of the channel. Under the condition that constraints such as water level, flow and water balance of power station operation are met, a reasonable adjusting period is set by combining actual conditions such as wharf operation conditions and ship loading and unloading time in a channel, a plurality of'large flow 'and'small flow' periodic tidal scheduling schemes are drawn up, and reservoir tidal scheduling adjustment calculation is started. And outputting the ex-warehouse flow of each time period as a final scheduling result. The tidal shipping scheduling mode that the hydropower station intermittently releases the airworthiness flow is provided by taking the actual power generation and shipping as the target, and through numerical simulation and reservoir regulation calculation, under the condition that the power generation requirement is met, the navigation requirement of the downstream reach of the power station is considered, and the win-win situation of multiple targets is achieved; and meanwhile, technical support is provided for hydropower station shipping optimization scheduling in the dry season.

Description

Technical Field

[0001] This invention relates to the field of hydropower dispatching technology, and more specifically to a tidal navigation dispatching method for hydropower stations under low water conditions. Background Technology

[0002] Since the 1980s, China's hydropower construction has experienced over 40 years of rapid development, and large-scale backbone cascade hydropower station groups have been basically completed on the country's major rivers. In addition to power generation, large hydropower stations typically undertake multiple tasks such as flood control, navigation, and irrigation. In recent years, with the increasing prominence of inland waterway transportation in the transportation system, the coordination between hydropower station operation and navigation has become increasingly important. Current research on reservoir navigation scheduling mainly focuses on the flood season, concentrating on adjusting flood discharge and controlling the peak-shaving range of power stations to improve navigation conditions, while research on optimized navigation scheduling during the dry season is relatively limited.

[0003] Currently, during the dry season, especially under extreme low water conditions, the demand for navigation imposes significant constraints on the operation and scheduling of hydropower stations. This is mainly reflected in the following aspects: (1) With the construction of large-scale cascade reservoirs, the large regulating capacity of reservoirs has greatly improved navigation conditions and promoted the development of large-scale inland waterway vessels. Under normal circumstances, vessels can pass through the waterway normally, but when encountering low water conditions, large vessels can only pass through with reduced load or empty, which can easily cause a large number of vessels to accumulate in the river section. (2) Hydropower station units are flexible in starting and stopping and can climb slopes quickly. They usually undertake the peak-shaving task of the power grid. Under low water conditions, when encountering low-load operation of the power station, the outflow from the power station decreases rapidly, which will further reduce the flow and water level of the downstream waterway, making it even more unfavorable for navigation in the downstream river section.

[0004] Therefore, under conditions of low water levels, a reservoir scheduling method is needed to achieve a win-win situation for multiple objectives, while meeting power generation requirements and taking into account the navigation needs of the downstream river section of the power station. This is the technical problem that this invention aims to solve. Summary of the Invention

[0005] To address the existing technical problems, the main objective of this invention is to provide a tidal navigation scheduling method for hydropower stations under low water conditions. By scientifically controlling the tidal increase or decrease of the outflow from the power station, the method can achieve a win-win situation for multiple objectives while meeting power generation requirements and taking into account the navigation needs of the downstream river section. To achieve the above-mentioned technical features, the objective of this invention is as follows: a method for tidal navigation scheduling of a hydropower station under low water conditions, comprising the following steps: Step 1, Basic Data Collection and Processing: Collect information on the power station's operation, the topography of the affected river channel, and information on wharves and vessels; Step 2, Determine the minimum navigable flow rate: Based on the basic data from Step 1, construct a one-dimensional hydrodynamic model, and combine the relationship between the ship's cargo load and draft to determine the minimum navigable flow rate; Step 3, Set constraints: Based on the basic data from Step 1, set the highest and lowest water levels, maximum and minimum flow rates, and water balance constraints to ensure the operation of the power station. Step 4, Set up the adjustment plan: Based on the actual situation of the dock operations in the waterway and the loading and unloading time of ships, set up a reasonable adjustment cycle and divide the period of high flow and low flow. Step 5, Reservoir Tidal Dispatch and Regulation Calculation: Based on the inflow volume, determine whether to initiate tidal navigation dispatch; after initiation, set the outflow volume during high-flow periods as the minimum navigable flow volume, and then calculate the outflow volume during low-flow periods through water balance. If the outflow volume during low-flow periods meets the constraints, output the calculation result; if the outflow volume during low-flow periods does not meet the constraints, reset the outflow volume during high-flow periods and iteratively calculate the outflow volume during low-flow periods until the outflow volume meets all constraints, and then output the outflow volume for each period as the final dispatch result.

[0006] Preferably, the basic data collection and processing in step 1 specifically includes the power station's inflow, outflow, water level-storage curve, downstream water level-flow relationship curve, power generation water consumption rate curve, channel cross-section, ship dimensions, water depth at the wharf front, and operating time.

[0007] Preferably, the ship dimensions include length, width, and draft.

[0008] Preferably, step 2, which involves determining the minimum navigable flow rate, specifically includes: establishing a one-dimensional hydrodynamic model of the power station's influence area, analyzing the relationship between ship load capacity and draft, and determining the minimum navigable flow rate that meets the ship's load requirements.

[0009] Preferably, in step 2, a one-dimensional hydrodynamic model of the power station's influence area is established to calculate the power station's outflow and the water depth along the channel. The governing equations are as follows: ; In the formula, A Cross-sectional area of ​​the flow path, m 2 ; t time, ; Q Flow rate, m 3 / s; x Horizontal distance in the direction of water flow, in meters; q Lateral inflow per unit river length, m 3 / s; Momentum correction factor; g Gravitational acceleration, m / s 2 ; hWater level, in meters (m); C Chey coefficient, m 0.5 / s; R Hydraulic radius, m.

[0010] Preferably, in step 2, when analyzing the relationship between ship loading and draft, cargo loading and draft data are statistically analyzed for ships of different tonnages, and the relationship is fitted by mathematical regression analysis to fit the curve of the relationship between ship loading and draft.

[0011] Preferably, in step 2, the minimum navigable flow rate to meet the loading requirements of ships is calculated by taking into account the relationship between the power station outflow and the water depth along the channel, as well as the relationship between the loading capacity and draft of the main vessels. This leads to the calculation of the relationship between the power station outflow and the loading capacity of the main vessels in the channel, and the determination of the minimum navigable flow rate under the condition that the main vessels are fully loaded or 90% fully loaded.

[0012] Preferably, the constraints set in step 3 mainly include flow constraints, water level constraints, initial and final water level control, and water balance constraints, as detailed below: (1) Water balance constraint: ; In the formula: For the reservoir in t Storage capacity at the end of the period, m 3 ; For the reservoir in t The inflow during a given period is fed by the outflow from its directly upstream reservoir, m 3 / s; For the reservoir in t Outbound flow rate during a given time period, m 3 / s, ; For the power station t Power generation flow rate during the period, m 3 / s; For the power station t The water discharge rate during the time period, m 3 / s; For time intervals; (2) Power generation flow limit: ; In the formula: Let m be the maximum and minimum power generation flow of the power plant. 3 / s; (3) Reservoir water level restrictions: ; In the formula: , These are the highest and lowest water levels during reservoir operation; For the reservoir int The final water level value for the time period, in meters (m). (4) Water level-reservoir capacity constraints, tailwater level-discharge: ; In the formula: This is a function of water level and reservoir capacity. This is a function relating the tailwater level to the discharge rate. For the reservoir in t The tailwater level during that period; For the reservoir in t Storage capacity for a given period of time; For the reservoir in t Hourly discharge volume; (5) Outbound flow limit: ; In the formula: These represent the maximum and minimum outflow rates of the reservoir, respectively, in m. 3 / s; (6) Flow constraints for each time period: ; In the formula: , Let m be the outflow rate during the low-flow and high-flow periods of the reservoir in each scenario. 3 / s; m , n , N These are the high-volume navigation time, low-volume navigation time, and total time period, respectively. For optimal airworthiness flow; This is the lower limit for navigable traffic volume; This represents the average outbound flow rate over the specified time period.

[0013] Preferably, in step 5, the condition for determining whether to initiate adjustment based on the inflow volume is: according to the rolling weekly forecast, the inflow volume is less than the minimum seaworthy flow for a consecutive week.

[0014] Preferably, in step 5, the recommended outflow rate for the "0" period during the low-flow discharge period in each scheme is [value missing]. The recommended outflow rate for the period of high-volume discharge "1" is [value missing]. ,calculate , The specific calculation rules are as follows: (a) Determine whether to initiate tidal shipping scheduling; when , For the inflow to the reservoir, if the forecast for the next week is that the inflow to the hydropower station is greater than the optimal navigable flow during the dry season in the downstream river section, the navigation conditions are good and no shipping scheduling is carried out; otherwise, tidal shipping scheduling is carried out and the process proceeds to step (b). (b) Set the initial flow ,make ; (c) The recommended outflow rate for the low-flow discharge period "0" is calculated as follows: Calculate based on the flow constraints for each time period in step 3. and judge Does the constraint satisfy? If Then let ;like ,but Then proceed to step (d) to calculate. ; (d) Calculate the recommended outflow rate for the large-flow discharge period "1". ;make Calculate based on the flow constraints for each time period in step 3. ,make .

[0015] Preferably, the high-volume and low-volume periods should be divided into two periods, which should be carried out alternately. Based on the loading and unloading patterns of the dock and ships and the demand of the power grid, 12h, 24h, 36h, and 48h should be set as time intervals.

[0016] The present invention has the following beneficial effects: 1. Based on practical considerations, this invention analyzes the relationship between the loading capacity of the main vessel types and the outflow in the river section affected by the hydropower station to determine the minimum navigable flow in the affected area. Combining the actual operation of power generation and dock vessels, a "tidal navigation scheduling" model for the intermittent release of navigable flow by the hydropower station is established, providing technical support for the optimized scheduling of hydropower station navigation during the dry season.

[0017] 2. The method of this invention, through "artificial tides," has significant benefits for shipping, power generation, and ecology. Firstly, it can greatly alleviate navigation pressure in the river sections affected by hydropower stations during the dry season, increasing navigation time for large vessels and improving cargo throughput per vessel. Secondly, it can increase the average daily head for power generation, improving water resource utilization. Thirdly, by controlling the periodic rise and fall of water levels above the dam, it can promote water exchange in the reservoir, potentially inhibiting algal blooms, thereby achieving a win-win situation for power generation, shipping, and ecology during the dry season. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a flowchart illustrating the principle of the method of the present invention.

[0020] Figure 2 A typical scheduling result is shown in the embodiment of this invention.

[0021] Figure 3 This is a diagram showing the scheduling results of the recommended scheme in an embodiment of the present invention. Detailed Implementation

[0022] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0023] Example 1: A method for tidal navigation scheduling of a hydropower station under low water conditions includes the following steps: Step 1, Basic Data Collection and Processing: Collect information on the power station's operation, the topography of the affected river channel, and information on wharves and vessels; Specifically, this includes the power station's inflow, outflow, water level-capacity curve, downstream water level-flow relationship curve, power generation water consumption rate curve, channel cross-section, vessel dimensions (length, width, and draft), water depth at the wharf front, and operating time.

[0024] Step 2, Determine the minimum navigable flow rate: Based on the basic data from Step 1, establish a one-dimensional hydrodynamic model of the power station's influence area, analyze the relationship between ship loading capacity and draft, and determine the minimum navigable flow rate to meet the ship loading requirements.

[0025] A one-dimensional hydrodynamic model of the power station's influence area was established to calculate the power station's outflow and the water depth along the channel. The governing equations are as follows: ; In the formula, A Cross-sectional area of ​​the flow path, m 2 ; t time, ; Q Flow rate, m 3 / s; x Horizontal distance in the direction of water flow, in meters; q Lateral inflow per unit river length, m 3 / s; Momentum correction factor; g Gravitational acceleration, m / s 2 ; h Water level, in meters (m); C Chey coefficient, m 0.5 / s; R Hydraulic radius, m; When analyzing the relationship between ship loading capacity and draft, cargo loading capacity and draft data of ships of different tonnages are statistically analyzed by category, and the relationship between ship loading capacity and draft is fitted by mathematical regression analysis. To determine the minimum navigable flow rate required to meet ship loading needs, the relationship between the power station outflow and the water depth along the channel, as well as the relationship between the main vessel's load capacity and draft, is calculated. This leads to the determination of the minimum navigable flow rate required to meet the full load or 90% full load requirements of the main vessels.

[0026] Step 3, Set constraints: Based on the basic data from Step 1, set the highest and lowest water levels, maximum and minimum flow rates, and water balance constraints to ensure the operation of the power station. Specifically, these include flow constraints, water level constraints, initial and final water level control, and water balance constraints, as detailed below: (1) Water balance constraint: ; In the formula: For the reservoir in t Storage capacity at the end of the period, m 3 ; For the reservoir in t The inflow during a given period is fed by the outflow from its directly upstream reservoir, m 3 / s; For the reservoir in t Outbound flow rate during a given time period, m 3 / s, ; For the power station t Power generation flow rate during the period, m 3 / s; For the power station t The water discharge rate during the time period, m 3 / s; For time intervals; (2) Power generation flow limit: ; In the formula: Let m be the maximum and minimum power generation flow of the power plant. 3 / s; (3) Reservoir water level restrictions: ; In the formula: , These are the highest and lowest water levels during reservoir operation; For the reservoir in t The final water level value for the time period, in meters (m). (4) Water level-reservoir capacity constraints, tailwater level-discharge: ; In the formula: This is a function of water level and reservoir capacity. This is a function relating the tailwater level to the discharge rate. For the reservoir in t The tailwater level during that period; For the reservoir in t Storage capacity for a given period of time; For the reservoir in t Hourly discharge volume; (5) Outbound flow limit: ; In the formula: These represent the maximum and minimum outflow rates of the reservoir, respectively, in m. 3 / s; (6) Flow constraints for each time period: ; In the formula: , Let m be the outflow rate during the low-flow and high-flow periods of the reservoir in each scenario. 3 / s; m , n , N These are the high-volume navigation time, low-volume navigation time, and total time period, respectively. For optimal airworthiness flow; This is the lower limit for navigable traffic volume; This represents the average outbound flow rate over the specified time period.

[0027] Step 4, Set up the adjustment plan: Based on the actual situation of the dock operations in the waterway and the loading and unloading time of ships, set up a reasonable adjustment cycle and divide the period of high flow and low flow. Preferably, in step 4, a navigation plan is set, and it is recommended to use a 7-day adjustment cycle based on the actual situation.

[0028] Step 5, Reservoir Tidal Dispatch and Regulation Calculation: Based on the inflow volume, determine whether to initiate tidal navigation dispatch; after initiation, set the outflow volume during high-flow periods as the minimum navigable flow volume, and then calculate the outflow volume during low-flow periods through water balance. If the outflow volume during low-flow periods meets the constraints, output the calculation result; if the outflow volume during low-flow periods does not meet the constraints, reset the outflow volume during high-flow periods and iteratively calculate the outflow volume during low-flow periods until the outflow volume meets all constraints, and then output the outflow volume for each period as the final dispatch result.

[0029] The condition for determining whether to initiate regulation based on the inflow volume is: according to the rolling weekly forecast, the inflow volume is less than the minimum seaworthy flow for one consecutive week.

[0030] For reservoir tidal regulation calculations, the recommended outflow rate during the low-flow discharge period ("0") in each scheme is [value missing]. The recommended outflow rate for the period of high-volume discharge "1" is [value missing]. ,calculate , The specific calculation rules are as follows: (a) Determine whether to initiate tidal shipping scheduling; when , For the inflow to the reservoir, if the forecast for the next week is that the inflow to the hydropower station is greater than the optimal navigable flow during the dry season in the downstream river section, the navigation conditions are good and no shipping scheduling is carried out; otherwise, tidal shipping scheduling is carried out and the process proceeds to step (b). (b) Set the initial flow ,make ; (c) The recommended outflow rate for the low-flow discharge period "0" is calculated as follows: Calculate based on the flow constraints for each time period in step 3. and judge Does the constraint satisfy? If Then let ;like ,but Then proceed to step (d) to calculate. ; (d) Calculate the recommended outflow rate for the large-flow discharge period "1". ;make Calculate based on the flow constraints for each time period in step 3. ,make .

[0031] Based on the above calculation rules, the scheduling rule table 1 is obtained.

[0032] Table 1 Scheduling Rules

[0033] Preferably, the high-volume and low-volume periods should be divided into two periods, which should be carried out alternately. Based on the loading and unloading patterns of the dock and ships and the demand of the power grid, 12h, 24h, 36h, and 48h should be set as time intervals.

[0034] Example 2: In this embodiment, the approximately 30-kilometer section of the Jinsha River from Xiangjiaba to Yibin is used as the navigation channel within the power station's influence area. Historical operational data of the Xiangjiaba Reservoir from April to June 2023 are selected, and the method provided by this invention is used to simulate and schedule the reservoir. The specific steps are as follows: Step 1: Basic Data Collection and Processing 1. First, obtain historical operational data for a certain reservoir. From April to June 2023, the inflow of water into the Jinsha River was significantly lower than normal, 20% lower than the average since the Jinsha River began operation (2022-2024). The discharge flow from Xiangjiaba was 2000 m³ / h. 3Large cargo ships frequently experience backlogs at around 1000 km / s. This invention example is based on the Xiangjiaba reservoir's water conditions from April to June 2023 (91 days). Historical water levels, inflows, outflows, and power output data for the reservoir from April to June 2023 were collected, as shown in Table 2.

[0035] Table 2 Historical Data

[0036] 2. Obtain information on the Xiangjiaba-Yibin waterway. The main shoals affecting navigation are as follows: Table 3. Statistics on the Risks of Streams and Beaches in the Xiangyi Section of the Jinsha River

[0037] 3. Currently, all vessels operating on the Yijiang section of the river use single-vessel transport, mainly dry bulk carriers, carrying primarily coal, phosphate rock, and sand and gravel. During the high-water season, this section can accommodate large vessels of 4,000-6,000 tons, while during the low-water season, the main vessels must reduce their load to approximately 1,000-2,000 tons. Through site visits and surveys at wharves along the river, comprehensive information on the main vessels navigating this section was collected; details of the main vessel types are shown in Table 4.

[0038] Table 4: Current Status of Major Vessel Types Navigating the Yijiang Section

[0039] Step 2: Determine the minimum navigable flow rate. Based on the data from Step 1, construct a one-dimensional hydrodynamic model and, considering the relationship between the ship's cargo load and draft, determine the minimum navigable flow rate. This mainly includes the following steps: Step 21: By establishing a hydrodynamic model of the power station's influence area, the relationship between the water depth along the channel and the power station's outflow is calculated. The Xiangyi section is the upstream extension of the Yangtze River channel, and its planned channel grade is Class III. This invention example is analyzed according to the Class III channel. According to the "Standards for Navigation of the Yangtze River Main Channel," the draft of a Class III channel is within the range of 2.4-3m, and the width is not less than 80m. This paper uses the MIKE11 hydrodynamic model to construct a one-dimensional hydrodynamic model of the Xiangjiaba to Yibin section, simulating the water depth along the channel under different outflow conditions at Xiangjiaba. It is concluded that the Shaowatuo section is the main shallow shoal section affecting the channel, and the water depth at this section restricts the overall channel depth scale.

[0040] The water depth at the Shaowatuo section is mainly affected by the outflow from Xiangjiaba Reservoir, the inflow from Hengjiang River, and the backwater effect of the Minjiang River. Since the Minjiang and Hengjiang Rivers have relatively low flow rates during the dry season, this paper sets their flow rates as fixed values ​​and simulates the relationship between different outflows from Xiangjiaba Reservoir and the water depth at the Shaowatuo section under this scenario. According to the "Standards for Navigation of the Yangtze River Main Channel," a margin of 0.3-0.4m is required for Class III waterways. Considering that the actual vessels navigating the Xiangjiaba-Yibin waterway have reached 4000-6000 tons and are significantly affected by the peak-shaving effect of the Xiangjiaba Hydropower Station, this invention considers a margin of 0.7m to further ensure navigation safety. The relationship between different outflows from Xiangjiaba Reservoir and the water depth at the Shaowatuo section is shown in Table 5 below.

[0041] Table 5 Relationship between navigable water depth at Shaowatuo section and outflow from Xiangjiaba Reservoir

[0042] Step 22: Statistically analyze the cargo load of major vessels within the waterway section. Classify and statistically analyze the cargo load and draft data of vessels of different tonnages, and use mathematical regression analysis to determine the relationship between cargo load and draft. Based on vessel dimensions, the main vessel types in this waterway section are divided into 1000-2500 ton and 3000-6000 ton ranges. For vessels in different tonnage ranges, analyze the regression analysis of cargo load and draft. The overall correlation is linear. The relationship between cargo load and draft for different tonnage vessels is shown in Table 6. Major vessels refer to the type of vessels comprising half or more of the total vessels in this waterway.

[0043] Table 6. Loading Capacity and Draft of Main Vessels in the Yijiang Section

[0044] Step 23: Combining the mapping relationship between Steps 21 and 22, deduce the relationship between the power station's outflow and the loading capacity of the main vessels in the waterway, and obtain the minimum navigable flow rate to meet the loading requirements of the main vessels. Based on the relationship between different outflows from Xiangjiaba and the water depth at the Shaowatuo section, and the relationship between the loading capacity and draft of the main vessel types, the relationship between the loading capacity of the main vessels and the outflow from Xiangjiaba is further deduced, as shown in Table 7 below.

[0045] Table 7 Relationship between Load Capacity of Main Ship Types and Outflow from Xiangjiaba Reservoir

[0046] The minimum navigable flow rate during the dry season mentioned in this invention refers to the minimum flow rate at which all ship types can navigate at full or near full load. As shown in Table 5, the outflow from Xiangjiaba Reservoir is 4500 m³ / s. 3 At a flow rate of / s, all vessels of different tonnages can sail fully loaded. Field research indicates that the main vessels typically carry around 5000 tons, meaning that when the outflow from Xiangjiaba Reservoir is 4000 m³ / s... 3At a flow rate of approximately 4000 m³ / s, all vessel types can navigate at full or near full capacity. Therefore, the optimal navigable flow rate during the dry season in the Xiangyi River section is currently determined to be 4000 m³ / s. 3 / s.

[0047] Step 3: Set constraints. The following constraints must be met for the power station's operation: maximum and minimum water levels, maximum and minimum flow rates, and water balance. Specific parameter settings: The Xiangjiaba control water level is set at the average water level of 375m for this period. The inflow rate is the actual inflow rate from April to June 2023, divided into 7-day cycles. The minimum navigable flow rate is set at 4000m³. 3 / s, the minimum outflow rate is set at 1500m³ / s according to relevant regulations of the Ministry of Transport. 3 / s.

[0048] Step 4: Set up navigation plans. Based on the actual conditions of wharf operations and ship loading / unloading times within the waterway, set a reasonable adjustment cycle and divide the period into high and low flow periods. Through actual research and considering the needs of ship owners, this paper sets up 5 adjustment plans with a 7-day adjustment cycle. Considering that the load is lower on Saturdays and Sundays in actual power dispatching, and the outflow from the Xiangjiaba Hydropower Station is correspondingly lower, this period is set as a low flow discharge of "0", allowing ships to load and unload during this time. On Mondays and Fridays, ships need to sail to transport goods, so it is set as a high flow discharge of "1". The flow from Tuesday to Thursday can be freely set. See Table 8 below for specific plans.

[0049] Table 8 High-volume navigation schemes

[0050] Note: "1" represents a period of high flow discharge; "0" represents a period of low flow discharge.

[0051] Step 5: Reservoir Tidal Regulation Calculation. Specifically, the calculation rule for cargo volume in the Xiangyi River section is as follows: Based on actual survey data, when the main vessel type's navigation flow rate is reached, navigation will primarily proceed according to the main vessel type's flow rate. When the flow rate does not meet the main vessel type's navigation conditions, vessels of all tonnage classes will be allocated proportionally, with the main vessel type's navigation flow rate set at 2500m³. 3 / s. Based on the relationship between the main vessel loading capacity and the outflow from Xiangjiaba Reservoir, the navigable freight volume for each time period is calculated. Due to the limited regulation capacity of the Xiangjiaba Hydropower Station during the dry season, it is usually controlled in a balanced inflow-outflow manner within short periods. To facilitate comparative analysis of changes in various indicators, a balanced inflow-outflow control scenario is added. The scheduling results for each scheme are as follows: Table 9 Simulation results for each scheduling method

[0052] Note: 1.3000m 3 The / s level range is 2900-3000m 3 / s, 4000m 3 The / s level range is 3600~4000m 3 / s. 2. This refers to the daily variation in water level at Xiangjiaba Dam.

[0053] By adopting the above-disclosed technical solution of this invention, the following beneficial effects are obtained: This invention provides a tidal navigation scheduling method for hydropower stations under low water conditions. By analyzing the relationship between the main vessel loading capacity and outflow in the river section affected by the hydropower station, the minimum navigable flow in the affected area is determined. Combined with the actual operation of power generation and dockside vessels, a "tidal navigation scheduling" model for the intermittent release of navigable flow by the hydropower station is established, providing technical support for optimized navigation scheduling of hydropower stations during the dry season. Simultaneously, this invention, through "artificial tides," can achieve a win-win situation for power generation, navigation, and ecology during the dry season. Firstly, it can significantly alleviate the navigation pressure on the Xiangyi River section during the dry season, increase the navigation time for large vessels, and increase the average cargo volume per vessel by 16%. Secondly, it can increase the average daily power generation head by 0.3m, improving water resource utilization. Thirdly, by controlling the periodic "rise and fall" of the water level above the Xiangjiaba Dam, it can promote water exchange in the reservoir and potentially inhibit algal blooms; however, the specific inhibitory effect on algal blooms in the Xiangjiaba reservoir area requires further in-depth research.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for tidal navigation scheduling of a hydropower station under low water conditions, characterized in that, Includes the following steps: Step 1, Basic Data Collection and Processing: Collect information on the power station's operation, the topography of the affected river channel, and information on wharves and vessels; Step 2, Determine the minimum navigable flow rate: Based on the basic data from Step 1, construct a one-dimensional hydrodynamic model, and combine the relationship between the ship's cargo load and draft to determine the minimum navigable flow rate; Step 3, Set constraints: Based on the basic data from Step 1, set the highest and lowest water levels, maximum and minimum flow rates, and water balance constraints to ensure the operation of the power station. Step 4, Set up the adjustment plan: Based on the actual situation of the dock operations in the waterway and the loading and unloading time of ships, set up a reasonable adjustment cycle and divide the period of high flow and low flow. Step 5, Reservoir Tidal Dispatch and Regulation Calculation: Determine whether to initiate tidal shipping dispatch based on the inflow volume; After startup, the outflow rate during high-flow periods is set as the minimum navigable flow rate. Then, the outflow rate during low-flow periods is calculated through water balance. If the outflow rate during low-flow periods meets the constraints, the calculation results are output. If the outbound flow during a low-flow period does not meet the constraints, the outbound flow during a high-flow period is reset, and the outbound flow during a low-flow period is iteratively calculated until the outbound flow meets all the constraints. Then, the outbound flow for each period is output as the final scheduling result.

2. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 1, characterized in that, The basic data collection and processing in step 1 specifically includes the power station's inflow, outflow, water level and reservoir capacity curve, downstream water level and flow relationship curve, power generation water consumption rate curve, channel cross-section, ship dimensions, water depth at the wharf front, and operating time.

3. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 2, characterized in that, The ship dimensions include length, width, and draft.

4. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 1, characterized in that, Step 2, which involves determining the minimum navigable flow rate, specifically includes: establishing a one-dimensional hydrodynamic model of the power station's influence area, analyzing the relationship between ship load capacity and draft, and determining the minimum navigable flow rate to meet ship load requirements.

5. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 4, characterized in that, In step 2, a one-dimensional hydrodynamic model of the power station's influence area is established to calculate the power station's outflow and the water depth along the channel. The governing equations are as follows: ； In the formula, A Cross-sectional area of ​​the flow path, m 2 ; t time, ; Q Flow rate, m 3 / s; x Horizontal distance in the direction of water flow, in meters; q Lateral inflow per unit river length, m 3 / s; Momentum correction factor; g acceleration due to gravity, m / s 2 ; h Water level, in meters (m); C Chey coefficient, m 0.5 / s; R Hydraulic radius, m.

6. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 4, characterized in that, In step 2, when analyzing the relationship between ship loading and draft, cargo loading and draft data of ships of different tonnages are statistically analyzed by category, and the relationship between ship loading and draft is fitted by mathematical regression analysis.

7. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 4, characterized in that, In step 2, the minimum navigable flow rate to meet the loading requirements of ships is calculated. Based on the relationship between the power station outflow and the water depth along the channel, as well as the relationship between the main vessel's loading capacity and draft, the relationship between the power station outflow and the main vessel's loading capacity in the channel is calculated, and the minimum navigable flow rate under the condition of the main vessel being fully loaded or 90% fully loaded is obtained.

8. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 4, characterized in that, The constraints set in step 3 mainly include flow constraints, water level constraints, initial and final water level control, and water balance constraints, as detailed below: (1) Water balance constraint: ； In the formula: For the reservoir in t Storage capacity at the end of the period, m 3 ; For the reservoir in t The inflow during a given period is fed by the outflow from its direct upstream reservoir, m 3 / s; For the reservoir in t Outbound flow rate during a given time period, m 3 / s, ; For the power station t Power generation flow rate during the period, m 3 / s; For the power station t The water discharge rate during the time period, m 3 / s; For time intervals; (2) Power generation flow limit: ； In the formula: The maximum and minimum power generation flow rates of the power plant are given by m. 3 / s; (3) Reservoir water level restrictions: ； In the formula: , These are the highest and lowest water levels during reservoir operation; For the reservoir in t The final water level value for the time period, in meters (m). (4) Water level-reservoir capacity constraints, tailwater level-discharge: ； In the formula: This is a function of water level and reservoir capacity. This is a function relating the tailwater level to the discharge rate. For the reservoir in t The tailwater level during that period; For the reservoir in t Storage capacity for a given period of time; For the reservoir in t Hourly discharge volume; (5) Outbound flow limit: ； In the formula: These represent the maximum and minimum outflow rates of the reservoir, respectively, in m. 3 / s; (6) Flow constraints for each time period: ； In the formula: , Let m be the outflow rate during the low-flow and high-flow periods of the reservoir in each scenario. 3 / s; m , n , N These are the high-volume navigation time, low-volume navigation time, and total time period, respectively. For optimal airworthiness flow; This is the lower limit for navigable traffic volume; This represents the average outbound flow rate over the specified time period.

9. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 4, characterized in that, In step 5, the condition for determining whether to initiate adjustment based on the inflow volume is: according to the rolling weekly forecast, the inflow volume is less than the minimum seaworthy flow for a consecutive week.

10. The method for tidal navigation scheduling of a hydropower station under low water conditions according to claim 8, characterized in that, In step 5, the recommended outflow rate for the reservoir's tidal regulation calculation during the low-flow discharge period ("0") in each scheme is: The recommended outflow rate for the period of high-volume outflow "1" is [value missing]. ,calculate , The specific calculation rules are as follows: (a) Determine whether to initiate tidal shipping scheduling; when , For the inflow to the reservoir, if the forecast for the next week is that the inflow to the hydropower station is greater than the optimal navigable flow during the dry season in the downstream river section, the navigation conditions are good and no shipping scheduling is carried out; otherwise, tidal shipping scheduling is carried out and the process proceeds to step (b). (b) Set the initial flow ,make ; (c) Calculate the recommended outflow rate for the low-flow discharge period "0". Calculate based on the flow constraints for each time period in step 3. and judge Does the constraint satisfy? If Then let ;like ,but Then proceed to step (d) to calculate. ; (d) Calculate the recommended outflow rate for the large-flow discharge period "1". ;make Calculate based on the flow constraints for each time period in step 3. ,make .

11. The method for tidal navigation scheduling of a hydropower station under low water conditions as described in claim 10, characterized in that, The periods of high and low traffic should be divided and should be carried out alternately. Based on the loading and unloading patterns of the dock and ships and the demand of the power grid, 12h, 24h, 36h and 48h should be set as time intervals.

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