A reservoir dispatching operation method

Abstract

The application provides a reservoir operation method, the reservoir comprises a reservoir, a hydropower station and a dam, the dam is provided with an overflow dam section, during a rainfall period, the inflow of the reservoir is predicted by a runoff prediction system, an optimal power generation scheme of the hydropower station is formulated in combination with the current reservoir water level, and the scheme is corrected in real time according to the hourly reservoir water level and the prediction result of the runoff prediction system, the efficient utilization of the reservoir and the hydropower station and the inflow is ensured through rolling scheme adjustment, and the utilization efficiency of the reservoir and the hydropower station on rainfall runoff is improved.

Description

[0001] Technical Field: This invention relates to the field of water conservancy engineering, and more specifically to a method for reservoir scheduling and operation.

[0002] Background Technology: Reservoir hydropower stations are a common type of hydropower station structure in my country. They regulate natural flow by constructing reservoirs to ensure the rational and efficient utilization of the flow. Reservoir hydropower stations also need to undertake certain flood control tasks. This is achieved by constructing spillway structures on the reservoir dam to ensure the discharge of floodwaters under flood conditions, thus guaranteeing structural safety. Constructing spillway sections on the dam is a common form of flood discharge design. Once the reservoir water level exceeds the elevation of the spillway section, the natural discharge will occur. During normal operation, the reservoir water level should be kept below the elevation of the spillway section to avoid water wastage.

[0003] During rainfall, the inflow to a reservoir increases, which generally requires increasing the load on the generating units and making the most of the rainfall. Although some reservoirs are equipped with runoff forecasting systems, there may be errors in the forecasted rainfall data during the rainfall period, which will also lead to errors in the runoff forecast. The accumulation of these errors may result in unreasonable start-up plans for reservoir hydropower stations, or cause the reservoir water level to be too high, resulting in unnecessary water wastage, or cause the reservoir water level to be too low, failing to effectively utilize rainfall runoff to raise the reservoir water level, resulting in a waste of water resources.

[0004] Summary of the Invention: This invention addresses the problems of existing technologies by providing a reservoir scheduling and operation method to achieve rational scheduling of reservoirs during rainfall periods.

[0005] This invention provides a reservoir scheduling and operation method. The reservoir is equipped with a dam, and a hydropower station is located downstream of the dam. The dam has an overflow section, and the hydropower station is connected to the reservoir via a pressure pipeline. The method is characterized by: the reservoir being equipped with a reservoir water level monitoring device and a rainfall measurement device. The reservoir water level monitoring device is used to monitor the reservoir water level, and the rainfall measurement device is used to obtain the rainfall at the dam site. The reservoir is equipped with a runoff forecasting system, which can obtain the hourly inflow of the reservoir for future periods. The reservoir only discharges water through the hydropower station. The method is characterized by: the elevation of the overflow section being H0; when the reservoir water level is higher than H0, the reservoir overflows. The scheduling and operation method is as follows:

[0006] S1: At the moment of rainfall, the hourly inflow Q1i from the current moment to the end of the rainfall period is predicted by the runoff forecasting system, and the reservoir water level H1 at the current moment is obtained. The reservoir water level H1 at the current moment is less than the elevation H0 of the overflow dam section.

[0007] S2: Set the hourly power generation flow rate Qg1 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg1 is always equal. Based on the hourly inflow rate Q1i, the hourly power generation flow rate Qg1, and the reservoir water level H1 at the current time, calculate the hourly reservoir water level H1i and the corresponding maximum reservoir water level H1max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H1max is the maximum value among the hourly reservoir water levels H1i.

[0008] S3: From the H1max corresponding to different power generation flows Qg1, find the maximum value H1m among all H1max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg10 corresponding to H1m. Based on the reservoir water level H1 and power generation flow Qg10 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H1 and power generation flow Qg10. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units.

[0009] S4: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S3, the reservoir water level H2 at the current moment is obtained, and the runoff forecasting system predicts the hourly inflow Q2i from the current moment to the end of the rainfall period.

[0010] S5: Set the hourly power generation flow rate Qg2 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg2 is always equal. Based on the hourly inflow rate Q2i, the hourly power generation flow rate Qg2, and the reservoir water level H2 at the current time, calculate the hourly reservoir water level H2i and the corresponding maximum reservoir water level H2max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H2max is the maximum value among the hourly reservoir water levels H2i.

[0011] S6: From the H2max corresponding to different power generation flows Qg2, find the maximum value H2m among all H2max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg20 corresponding to H2m. Based on the reservoir water level H2 and power generation flow Qg20 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H2 and power generation flow Qg20. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units.

[0012] S7: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S6, the reservoir water level H3 at the current moment is obtained. The runoff forecasting system predicts the hourly inflow Q3i from the current moment to the end of the rainfall period, and repeats steps S5-S6 until the end of the rainfall period.

[0013] Preferably, the runoff forecasting system can acquire predicted hourly rainfall data for future periods and predict the hourly inflow of the reservoir for future periods based on the predicted hourly rainfall data for future periods.

[0014] Preferably, the time when the rainfall ends is obtained based on hourly weather forecasts.

[0015] Preferably, the method for calculating the hourly reservoir water level from the current moment to the end of the rainfall period according to the reservoir water balance equation is as follows: obtain the reservoir water level at the current moment, calculate the reservoir capacity at the current moment according to the water level-capacity curve, obtain the inflow and power generation flow for the next hour, and calculate the storage flow and storage volume for the next hour. Add the reservoir capacity at the current moment to the storage volume for the next hour to obtain the reservoir capacity for the next hour. Calculate the reservoir water level for the next hour based on the storage capacity for the next hour and the water level-capacity curve. Repeat this water balance calculation until the end of the period.

[0016] As a preferred option, the in-plant optimization calculation of the reservoir hydropower station is as follows: based on the reservoir water level and power generation flow, conduct trial allocation of the unit start-up combination and the load of the start-up units, and find the allocation scheme with the largest total unit load under the reservoir water level and power generation flow.

[0017] The working principle of this invention is as follows:

[0018] In this invention, when the reservoir water level exceeds the elevation of the overflow dam section, the discharge flow rate at the overflow dam section elevation is adopted. When the reservoir water level is lower than the overflow dam section elevation, the discharge flow rate of the hydropower station is adopted. During the operation of the reservoir, a high water level is maintained as much as possible to increase the power generation head. However, the reservoir water level should be lower than the overflow dam section elevation to avoid water waste caused by water being discharged through the overflow dam section.

[0019] During periods of rainfall, the increased inflow into the reservoir can lead to several problems. If the generator load is set too low, the reservoir level may rise too quickly, exceeding the spillway elevation and resulting in wasted water discharge. Conversely, if the generator load is set too high, the reservoir level may drop, reducing the hydroelectric head. Furthermore, while hourly rainfall forecasts can provide data on future rainfall amounts, and the runoff forecasting system can calculate the hourly inflow into the reservoir based on these amounts for scheduling purposes, weather forecasts are updated as rainfall progresses. Additionally, the runoff forecasting system's calculations of inflow based on rainfall amounts are subject to error. Therefore, relying solely on weather and runoff forecasts to guide reservoir operation is insufficient.

[0020] The operating method proposed in this invention adopts an hourly correction approach. That is, for the formulated optimized operating plan, after one hour of execution, the reservoir water level is reacquired and the runoff forecasting system is re-forecasted. At this time, the weather forecast data obtained by the runoff forecasting system is updated, and its prediction accuracy is higher than that of the previous hour. By performing rolling optimization, the accuracy of the plan can be continuously improved, avoiding water wastage or operation at low water levels.

[0021] For the optimization scheme formulation, firstly, hourly rainfall data for the future period (from the current moment to the end of rainfall, where the end of rainfall can be obtained from weather forecast data) is obtained. Then, the runoff forecasting system generates hourly inflow data based on the hourly rainfall data, sets the power generation flow rate of the reservoir hydropower station, where the power generation flow rate adopts an equal hourly flow rate. Based on the reservoir water balance principle, the hourly reservoir water level change value is calculated, and the maximum reservoir water level corresponding to different power generation flow rates is obtained. The maximum reservoir water level value less than the maximum value in the overflow dam section elevation is selected as the optimization scheme. This scheme indicates that using this power generation flow rate can ensure that the reservoir water level rises to the high water level during the period from the current moment to the end of rainfall without overflow. This power generation flow rate is used as the start-up scheme flow rate of the reservoir hydropower station. Based on the plant optimization theory, with the goal of maximizing the power generation load of the hydropower station, trial allocation of unit flow is carried out to find the set of different allocation schemes that maximizes the load of the hydropower station as the optimized start-up scheme.

[0022] Rolling correction can avoid the accumulation of errors, especially in the case of inaccurate inflow during the period that has already occurred, which may cause the reservoir water level to not change according to the preset reservoir water level. However, in the next period, the reservoir water level is re-acquired and optimized, which can eliminate the error. Through rolling correction, each plan is formulated based on the current data in the optimal state, until the rainfall period ends and the reservoir inflow returns to the normal level, so as to realize the rational utilization of the inflow during the rainfall period.

[0023] The advantages of this invention are:

[0024] This invention provides a reservoir scheduling and operation method. The reservoir includes a reservoir, a hydropower station, and a dam. The dam is equipped with an overflow section. During rainfall periods, the inflow to the reservoir is predicted by a runoff forecasting system. Based on the current reservoir water level, the optimal power generation scheme of the hydropower station is formulated. The scheme is then adjusted in real time according to the hourly reservoir water level and the forecast results of the runoff forecasting system. Through rolling adjustments, the efficient utilization of the reservoir and hydropower station and the inflow is ensured, thereby improving the utilization efficiency of the reservoir and hydropower station for rainfall runoff.

[0025] Detailed Implementation: The following provides a detailed explanation of the scope of this invention.

[0026] This invention provides a reservoir scheduling and operation method. The reservoir is equipped with a dam, and a hydropower station is located downstream of the dam. The dam has an overflow section, and the hydropower station is connected to the reservoir via a pressure pipeline. The method is characterized by: the reservoir being equipped with a reservoir water level monitoring device and a rainfall measurement device. The reservoir water level monitoring device is used to monitor the reservoir water level, and the rainfall measurement device is used to obtain the rainfall at the dam site. The reservoir is equipped with a runoff forecasting system, which can obtain the hourly inflow of the reservoir for future periods. The reservoir only discharges water through the hydropower station. The method is characterized by: the elevation of the overflow section being H0; when the reservoir water level is higher than H0, the reservoir overflows. The scheduling and operation method is as follows:

[0027] S1: At the moment of rainfall, the hourly inflow Q1i from the current moment to the end of the rainfall period is predicted by the runoff forecasting system, and the reservoir water level H1 at the current moment is obtained. The reservoir water level H1 at the current moment is less than the elevation H0 of the overflow dam section.

[0028] S2: Set the hourly power generation flow rate Qg1 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg1 is always equal. Based on the hourly inflow rate Q1i, the hourly power generation flow rate Qg1, and the reservoir water level H1 at the current time, calculate the hourly reservoir water level H1i and the corresponding maximum reservoir water level H1max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H1max is the maximum value among the hourly reservoir water levels H1i.

[0029] S3: From the H1max corresponding to different power generation flows Qg1, find the maximum value H1m among all H1max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg10 corresponding to H1m. Based on the reservoir water level H1 and power generation flow Qg10 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H1 and power generation flow Qg10. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units.

[0030] S4: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S3, the reservoir water level H2 at the current moment is obtained, and the runoff forecasting system predicts the hourly inflow Q2i from the current moment to the end of the rainfall period.

[0031] S5: Set the hourly power generation flow rate Qg2 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg2 is always equal. Based on the hourly inflow rate Q2i, the hourly power generation flow rate Qg2, and the reservoir water level H2 at the current time, calculate the hourly reservoir water level H2i and the corresponding maximum reservoir water level H2max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H2max is the maximum value among the hourly reservoir water levels H2i.

[0032] S6: From the H2max corresponding to different power generation flows Qg2, find the maximum value H2m among all H2max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg20 corresponding to H2m. Based on the reservoir water level H2 and power generation flow Qg20 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H2 and power generation flow Qg20. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units.

[0033] S7: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S6, the reservoir water level H3 at the current moment is obtained. The runoff forecasting system predicts the hourly inflow Q3i from the current moment to the end of the rainfall period, and repeats steps S5-S6 until the end of the rainfall period.

[0034] The runoff forecasting system can access rainfall prediction data from weather forecasts and obtain hourly rainfall data, as well as the time when the rainfall ends. The rainfall data is updated in real time, and a rolling method of updating once per hour is adopted to ensure that the reservoir and hydropower station do not make frequent adjustments.

[0035] When predicting reservoir inflow in the future, the runoff forecasting system can also make predictions based on the rainfall data that has already occurred and the rainfall in the future. The prediction method adopts a short-term runoff forecasting model based on hydrology.

[0036] Preferably, the runoff forecasting system can acquire predicted hourly rainfall data for future periods and predict the hourly inflow of the reservoir for future periods based on the predicted hourly rainfall data for future periods.

[0037] Preferably, the time when the rainfall ends is obtained based on hourly weather forecasts.

[0038] Preferably, the method for calculating the hourly reservoir water level from the current moment to the end of the rainfall period according to the reservoir water balance equation is as follows: obtain the reservoir water level at the current moment, calculate the reservoir capacity at the current moment according to the water level-capacity curve, obtain the inflow and power generation flow for the next hour, and calculate the storage flow and storage volume for the next hour. Add the reservoir capacity at the current moment to the storage volume for the next hour to obtain the reservoir capacity for the next hour. Calculate the reservoir water level for the next hour based on the storage capacity for the next hour and the water level-capacity curve. Repeat this water balance calculation until the end of the period.

[0039] As a preferred option, the in-plant optimization calculation of the reservoir hydropower station is as follows: based on the reservoir water level and power generation flow, conduct trial allocation of the unit start-up combination and the load of the start-up units, and find the allocation scheme with the largest total unit load under the reservoir water level and power generation flow.

[0040] The reservoir hydropower station is equipped with an automatic control system, which is connected to the reservoir water level monitoring device, rainfall monitoring device, and runoff forecasting system. The runoff forecasting system is connected to a weather forecasting module. The automatic control system includes a reservoir water balance calculation submodule and an in-plant optimization calculation submodule. The reservoir water balance calculation submodule can automatically calculate the reservoir water level for future time periods based on hourly inflow, hourly power generation flow, overflow dam crest elevation, reservoir water level-overflow curve, water level-storage capacity curve, and current reservoir water level. The in-plant optimization calculation submodule can perform in-plant optimization calculations based on the current reservoir water level and power generation flow, combined with the unit operating characteristic curve, tailrace flow curve, and water diversion system losses, to provide the optimal start-up scheme. The optimal start-up scheme includes the start-up combination and the corresponding load value of the start-up unit.

[0041] The above embodiments are merely preferred embodiments of the present invention. The scope of protection of the present invention should not be considered as limited to the specific forms described in the embodiments. The scope of protection of the present invention also includes equivalent technical means that can be conceived by those skilled in the art based on the concept of the present invention.

Claims

1. A method for reservoir scheduling and operation, wherein the reservoir is equipped with a dam, a hydropower station is located downstream of the dam, the dam has an overflow section, and the hydropower station is connected to the reservoir via a pressure pipeline, characterized in that: The reservoir is equipped with a reservoir water level monitoring device and a rainfall measurement device. The reservoir water level monitoring device is used to monitor the reservoir water level, and the rainfall measurement device is used to obtain the rainfall at the dam site. The reservoir is equipped with a runoff forecasting system, which can obtain the hourly inflow of the reservoir for future periods. The reservoir only discharges water through the hydropower station. The reservoir is characterized by: the elevation of the overflow dam section being H0; when the reservoir water level is higher than H0, the reservoir overflows. The scheduling and operation method is as follows: S1: At the moment of rainfall, the hourly inflow Q1i from the current moment to the end of the rainfall period is predicted by the runoff forecasting system, and the reservoir water level H1 at the current moment is obtained. The reservoir water level H1 at the current moment is less than the elevation H0 of the overflow dam section. S2: Set the hourly power generation flow rate Qg1 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg1 is always equal. Based on the hourly inflow rate Q1i, the hourly power generation flow rate Qg1, and the reservoir water level H1 at the current time, calculate the hourly reservoir water level H1i and the corresponding maximum reservoir water level H1max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H1max is the maximum value among the hourly reservoir water levels H1i. S3: From the H1max corresponding to different power generation flows Qg1, find the maximum value H1m among all H1max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg10 corresponding to H1m. Based on the reservoir water level H1 and power generation flow Qg10 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H1 and power generation flow Qg10. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units. S4: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S3, the reservoir water level H2 at the current moment is obtained, and the runoff forecasting system predicts the hourly inflow Q2i from the current moment to the end of the rainfall period. S5: Set the hourly power generation flow rate Qg2 of the reservoir hydropower station from the current time to the end of the rainfall period. The hourly power generation flow rate Qg2 is always equal. Based on the hourly inflow rate Q2i, the hourly power generation flow rate Qg2, and the reservoir water level H2 at the current time, calculate the hourly reservoir water level H2i and the corresponding maximum reservoir water level H2max from the current time to the end of the rainfall period according to the reservoir water balance equation. The maximum reservoir water level H2max is the maximum value among the hourly reservoir water levels H2i. S6: From the H2max corresponding to different power generation flows Qg2, find the maximum value H2m among all H2max that is less than the elevation H0 of the spillway section, and find the power generation flow Qg20 corresponding to H2m. Based on the reservoir water level H2 and power generation flow Qg20 at the current moment, perform in-plant optimization calculations for the reservoir hydropower station to obtain the optimal start-up scheme for the reservoir hydropower station under the reservoir water level H2 and power generation flow Qg20. The optimal start-up scheme includes the combination of start-up units and the start-up load corresponding to the start-up units. S7: After the reservoir hydropower station operates for 1 hour according to the optimal start-up scheme obtained in S6, the reservoir water level H3 at the current moment is obtained. The runoff forecasting system predicts the hourly inflow Q3i from the current moment to the end of the rainfall period, and repeats steps S5-S6 until the end of the rainfall period.

2. The reservoir scheduling and operation method as described in claim 1, characterized in that: The runoff forecasting system can acquire predicted hourly rainfall data for future periods and predict the hourly inflow of the reservoir for future periods based on the predicted hourly rainfall data for future periods.

3. The reservoir scheduling and operation method as described in claim 1, characterized in that: The time when the rainfall ends is obtained from hourly weather forecasts.

4. The reservoir scheduling and operation method as described in claim 1, characterized in that: According to the reservoir water balance equation, the method for calculating the hourly reservoir water level from the current moment to the end of the rainfall period is as follows: obtain the reservoir water level at the current moment, calculate the reservoir capacity at the current moment according to the water level-capacity curve, obtain the inflow and power generation flow for the next hour, and calculate the storage flow and storage volume for the next hour. Add the reservoir capacity at the current moment to the storage volume for the next hour to obtain the reservoir capacity for the next hour. Calculate the reservoir water level for the next hour based on the storage capacity for the next hour and the water level-capacity curve. Repeat this water balance calculation until the end of the period.

5. The reservoir scheduling and operation method as described in claim 1, characterized in that: The optimization calculation within the reservoir hydropower station is as follows: based on the reservoir water level and power generation flow, the plant's unit start-up combination and the load of the start-up units are trial-allocated to find the allocation scheme with the largest total unit load under the reservoir water level and power generation flow.