Cascade hydropower station scheduling method considering supply insurance and flood prevention restriction relation

Abstract

The invention relates to the technical field of hydroelectric power generation, and discloses a cascade hydropower station scheduling method considering supply guarantee and flood prevention restriction relation, which comprises the following steps: analyzing power generation characteristics of cascade hydropower stations, carrying out centralized hydro-fluctuation control on a reservoir with regulation capability through a simulation experiment method, determining the optimal hydro-fluctuation time, and establishing a pre-flood water level hydro-fluctuation time constraint; the maximum generating capacity and the minimum abandoned water amount are taken as targets, a pre-flood water level fluctuation time constraint and a hydropower station basic constraint are combined, an electric power supply guarantee constraint and a flood control constraint are considered, a coordinated optimization scheduling model of the hydropower station is constructed and solved, an optimal scheduling scheme is generated, and efficient utilization of water resources and maximization of electric power are achieved. According to the method, optimal dispatching of combined operation of the cascade hydropower stations is achieved, the water level of the hydropower stations is effectively adjusted, water waste is reduced, meanwhile, the power generation efficiency is improved, and the supply protection capacity under different inflow water conditions is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of hydropower generation, and in particular to a scheduling method for cascade hydropower stations taking into account the constraints between power supply guarantee and flood prevention. Background Art

[0002] The power system is currently transitioning towards a green and low-carbon economy. Large-scale development of hydropower, a renewable, pollution-free, and highly peak-shaving clean energy source, is an inevitable choice for meeting clean energy demand and improving system flexibility. Cascade hydropower, with its large capacity, rapid response, and flexible regulation capabilities, is considered a key way to promote large-scale renewable energy consumption and effectively alleviate the pressure on the supply-demand balance of power grids with a high proportion of clean energy. The major river basins in Southwest China enjoy abundant water flows, but this flow is highly seasonal, with flood season water inflow accounting for approximately 70% of the annual total. To optimize water resource allocation, controlled reservoirs in each river basin are necessary to regulate water flows, redistributing natural water flows. The reservoir clusters that have gradually emerged across the river basins of Southwest China effectively address the uneven spatial and temporal distribution of water resources in the basins. The way these reservoirs operate significantly impacts water resource utilization in the basins. The pre-flood season drawdown is a critical stage in the transition from normal water levels to flood season. To meet flood control storage capacity and summer power generation needs, reservoirs responsible for flood control should gradually lower their water levels to below the flood control limit before the flood season, while also controlling the water level to ensure that users can meet the large electricity demand in the summer. If the water level does not drop sufficiently, the reservoir's storage and regulation function will be limited, and flood discharges may be required, resulting in water abandonment, wasting water resources or causing man-made flood disasters. If the water level drops too much, the head will decrease, and the power generation capacity will drop, which may lead to power supply shortages. At the same time, the water storage capacity will decrease, the total power generation will decrease, and the power supply risk will increase. Therefore, it is necessary to propose a joint operation and scheduling method for cascade hydropower stations that can not only ensure that the water level does not rise too high before the flood season, and that water abandonment is reduced during the flood season, thereby reducing flood control risks, but also meet the large electricity demand of users during the peak summer electricity demand period.

[0003] In summary, the research on the joint operation and dispatching of cascade hydropower stations has the following main deficiencies: (1) The research on the optimal dispatching of reservoirs only considers the impact of a single supply guarantee or flood control factor, without comprehensively considering the two situations of supply guarantee and flood control constraints and the impact of their constraints; (2) The water level control operation rarely considers the separate control of the water level before the flood season. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, the present invention provides a scheduling method for cascade hydropower stations that takes into account the constraints between supply guarantee and flood prevention, so as to solve the problems that the existing scheduling method for cascade hydropower stations does not take into account a single flood guarantee or flood prevention factor and does not introduce separate control of the pre-flood water level, thereby leading to water waste and low power generation efficiency.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: A method for dispatching cascade hydropower stations taking into account the constraints between power supply guarantee and flood prevention includes the following steps: S1. Analyze the power generation characteristics of cascade hydropower stations, conduct centralized water level drawdown control on reservoirs with regulatory capabilities through simulation experiments, determine the optimal drawdown time, and establish pre-flood water level drawdown time constraints; S2. With the goal of maximizing power generation and minimizing water abandonment, combined with the pre-flood water level drawdown time constraints and hydropower station infrastructure constraints, and considering power supply security constraints and flood control constraints, a coordinated optimization scheduling model for the hydropower station is constructed and solved to generate the optimal scheduling plan to achieve efficient use of water resources and maximize power generation.

[0006] The present invention has the following beneficial effects: The present invention proposes a scheduling method for cascade hydropower stations that takes into account the constraints of power supply security and flood prevention. It comprehensively considers the constraints of power supply security and flood control, establishes a coordinated optimization scheduling model for hydropower stations, realizes the optimized scheduling of the joint operation of cascade hydropower stations, effectively regulates the water level of the hydropower stations, reduces water waste, improves power generation efficiency, and ensures the power supply capacity under different water inflow conditions; at the same time, it also adjusts the degree of water level drop before the flood season by controlling the water level of centralized pumping before the flood season, and takes into account the power supply security and flood control requirements of cascade hydropower stations, thereby verifying its scientific rationality and feasibility in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a flow chart of a method for dispatching cascade hydropower stations that takes into account the constraints between supply guarantee and flood prevention, as proposed by the present invention; Figure 2 Schematic diagram comparing the optimized solution and the actual solution of the hydropower station 1 in the embodiment; Figure 3 Schematic diagram comparing the optimized solution and the actual solution of Hydropower Station 2 in the embodiment; Figure 4 Schematic diagram comparing the optimized solution and the actual solution of the hydropower station 3 in the embodiment; Figure 5 A comparative schematic diagram of the optimization schemes corresponding to different water supply conditions in the embodiment; Figure 6 A comparative schematic diagram of the optimization schemes corresponding to different water supply conditions in the embodiment; Figure 7 Schematic diagram for comparing optimization solutions corresponding to different water inflow conditions in the embodiment. DETAILED DESCRIPTION

[0008] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0009] like Figure 1 As shown, a method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention includes the following steps S1-S2: S1. Analyze the power generation characteristics of cascade hydropower stations, conduct centralized drawdown control on reservoirs with regulation capabilities through simulation experiments, determine the optimal drawdown time, and establish pre-flood water level drawdown time constraints.

[0010] Specifically, the water level drawdown time constraint before the flood season is:

[0011] in, Indicates the time constraint of water level drawdown before flood season. Indicates the best disappearance time, 、 、 Respectively represent The hydropower station in , No. , No. The water level of the moon.

[0012] In this embodiment, the operation and scheduling of cascade hydropower stations is taken as the research object, and the simulation experiment method is used to determine the optimal drawdown time of the reservoir, thereby establishing the pre-flood water level drawdown time constraint. Specifically, first, the power generation characteristics of the cascade hydropower station are analyzed, and it is found that the operation of the entire cascade hydropower station is affected by the upstream water, and the operation of the downstream power station is limited by the regulation capacity of the upstream reservoir. Therefore, in order to improve the power generation efficiency and power supply reliability, it is necessary to conduct centralized drawdown control on reservoirs with regulation capacity, that is, by appropriately extending the centralized drawdown period of the regulating reservoir, enhancing the flexibility of power scheduling during this period, and reducing the impact of ecological and sediment scheduling on reservoir drawdown. However, if the drawdown period is extended in advance, although it will not increase the flood risk downstream, it may reduce the power generation efficiency of the reservoir. Therefore, this embodiment determines the optimal drawdown time of the reservoir through the simulation experiment method to achieve the optimized operation of the cascade hydropower station. Among them, the simulation experiment controlled different pre-flood water level drawdown times, obtained results through conventional model operation, compared the total power generation and total water abandonment at different times, and took the plan with the maximum total power generation and the minimum water abandonment as the optimal pre-flood water level drawdown time plan.

[0013] S2. With the goal of maximizing power generation and minimizing water abandonment, combined with the pre-flood water level drawdown time constraints and hydropower station infrastructure constraints, and considering power supply security constraints and flood control constraints, a coordinated optimization scheduling model for the hydropower station is constructed and solved to generate the optimal scheduling plan to achieve efficient use of water resources and maximize power generation.

[0014] Specifically, the basic constraints of a hydropower station include hydraulic constraints of upstream and downstream hydropower stations, water quantity coupling constraints, initial and final storage capacity constraints, hydropower station flow relationship constraints, water level and storage capacity relationship constraints, upper and lower limit constraints, and head constraints. The corresponding formulas are:

[0015] in, represents the hydraulic constraints of upstream and downstream hydropower stations, Indicates the water flow lag between hydropower stations. Indicates the The hydropower station in Inflow flow at any moment, Indicates the The hydropower station in The power generation flow at the moment, Indicates the Moment The hydropower station and The flow between hydropower stations.

[0016]

[0017] in, represents the water quantity coupling constraint, represents the storage capacity of the first hydropower station, Indicates the The storage capacity of a hydropower station, represents the initial storage capacity of the first hydropower station, Indicates the The initial storage capacity of a hydropower station, Indicates that the first hydropower station is in Inflow flow at any moment, Indicates that the first hydropower station is in Outbound flow at any given moment, Indicates the The hydropower station in Outbound flow at any given moment, Indicates the The hydropower station in Outbound flow at a given moment.

[0018]

[0019] in, represents the initial and final storage capacity constraints, 、 Respectively represent The target control storage capacity of each hydropower station in the initial dispatching period, The target control storage capacity of each hydropower station at the end of the dispatch period is: Indicates the The actual controlled storage capacity of a hydropower station at the end of the dispatching period.

[0020] In this embodiment, the initial scheduling period is the first month of each year, and the final scheduling period is the last month of each year (December).

[0021]

[0022] in, represents the flow relationship constraint of the hydropower station, Indicates the Outbound flow at any given moment, Indicates the The power generation flow at the moment, Indicates the The abandoned water flow at the moment.

[0023]

[0024] in, represents the relationship constraint between water level and reservoir capacity, Indicates the The water level of the hydropower station at the moment, represents the relationship function between water level and reservoir capacity, Indicates the The reservoir capacity of the hydropower station at the moment.

[0025] In this embodiment, the relationship between water level and reservoir capacity is relatively linear, and a linear function can be used for fitting. The function form of the linear fitting is: ,in, Represents storage capacity, Indicates the water level, 、 They all represent fitting parameters, which can be estimated by statistical methods such as the least squares method.

[0026]

[0027] in, Indicates upper and lower limit constraints, 、 Respectively represent the minimum and maximum storage capacity of the hydropower station, 、 Represent the minimum and maximum power generation flow, Indicates the maximum water discharge rate, 、 Represent the minimum and maximum outbound flows, Indicates the The power generation at the moment, 、 Represent the minimum and maximum power generation respectively.

[0028]

[0029] in, represents the head constraint, Indicates the The water head of the moment, Indicates the Tailwater level at the moment.

[0030] Specifically, power supply security constraints include power generation security rate constraints and hydropower output relationship constraints, and their corresponding formulas are:

[0031] in, represents the power generation guarantee rate constraint, represents the number of hydropower stations, Indicates the first The hydropower station in The power generation at the moment, Indicates the time interval, Indicates the load amount.

[0032]

[0033] in, Represents the hydropower output constraint, Represents the hydropower generation coefficient.

[0034] In this embodiment, power supply security constraints are taken into consideration to ensure stable and reliable operation of the power system, meet the electricity demand for social production and life, promote economic development, ensure the stability of people's livelihood, improve energy utilization efficiency, and promote energy transformation and sustainable development.

[0035] Specifically, flood control constraints include water level change constraints, water level change rate constraints, and flood season constraints, and their corresponding formulas are:

[0036] in, represents the water level change constraint, Indicates the The hydropower station in The water level at the moment, Indicates the The hydropower station in The water level at the moment, Indicates the The maximum water level change allowed for a hydropower station in one day.

[0037]

[0038] in, Indicates flood season constraints, Indicates the The water level of a hydropower station during flood season.

[0039] In this embodiment, flood control constraints are intended to reduce the scope and risk of flooding, protect people's lives and livelihoods, reduce property losses, and maintain the normal operation of the social economy.

[0040] Specifically, the coordinated optimization scheduling model of the hydropower station is:

[0041]

[0042] in, represents the coordinated optimization scheduling model of hydropower stations, Respectively represent the minimum and maximum values, Indicates the first The hydropower station in The abandoned water flow at the time, To satisfy it, Indicates the The hydropower station in Hydropower generation capacity at the time, Indicates the total number of months in the scheduling period.

[0043] In this embodiment, with the goal of maximizing power generation and minimizing water abandonment, a coordinated optimization scheduling model for the hydropower station is constructed, combining the pre-flood water level drawdown time constraint with the basic constraints of the hydropower station, and considering the power supply guarantee constraint and flood control constraint. This model comprehensively considers key factors such as the hydropower station's flow relationship, the nonlinear relationship between water level and energy storage, and the flood season, ensuring that the hydropower station can operate effectively under different hydrological conditions. Ultimately, by solving this model, the hydropower station's scheduling plan is optimized, the utilization efficiency of water resources is improved, and this method meets the power supply needs and flood control safety requirements of the power system. Among them, the power generation is obtained by multiplying the maximum power generation power by time. That is, when the optimal hydropower generation power is obtained, the optimal power generation can be obtained, that is, the power is maximized.

[0044] In addition, to verify the effectiveness of the proposed method for scheduling cascade hydropower stations that considers the constraints between supply guarantee and flood prevention, the following experiments were conducted using a cascade hydropower station group in a certain river basin in the southwest region as the research object: First, the region contains a total of 7 hydropower stations, including 3 seasonal regulation and above hydropower stations. The basic information of the 3 hydropower stations is shown in Table 1: Table 1 Basic information of long-term regulation hydropower stations in a certain river basin in Southwest China

[0045] Secondly, the method proposed in this invention is used to optimize the scheduling of the cascade hydropower station group in a certain river basin in the southwest region; by inputting the monthly average flow of historical years respectively, the water level control comparison of seasonal regulation and above hydropower stations can be obtained, as shown in the following figure. Figure 2-Figure 4 As shown, Figure 2-Figure 4 The optimized solution is obtained by using the method proposed in this invention, and the actual solution is obtained by using the actual data. Figure 2-Figure 4 By comparing the optimization scheme and the actual scheme in the simulation, it can be observed that the water level regulation scheme of the optimization model is relatively close to the actual scheme. This phenomenon shows that the optimization of the scheduling of cascade hydropower stations using the method proposed in the present invention is highly reasonable and feasible. That is, under various uncertain conditions, the optimization scheme generated by the method proposed in the present invention can effectively simulate a water level regulation path that is relatively close to the actual operating conditions, and the water level difference between the two is small. Therefore, the method proposed in the present invention provides theoretical support for actual operation and verifies its scientific rationality.

[0046] also, Figure 5-Figure 7 This is a comparison chart of multiple water supply scenarios. Figure 2-Figure 7 From the optimization scheme, actual scheme and water inflow scheme in the paper, it can be observed that the optimization scheme is relatively close to the schemes under different water inflow conditions. This phenomenon shows that the optimization scheme generated by the proposed method has high adaptability in water level scheduling under different water inflow conditions, that is, under various uncertain water inflow conditions, the optimization model runs and simulates a more reasonable water level regulation path, and the optimization scheme is relatively consistent with the water level regulation strategy of the multi-scenario water inflow scheme.

[0047] Then, the results of the optimization scheme generated by the method proposed in the present invention and the actual scheme are compared and analyzed. The results of power generation and water abandonment are shown in Table 2: Table 2 Comparison of total power generation and water abandonment in a river basin in the southwest region

[0048] It can be seen from Table 2 that the optimization scheme generated by the method proposed in the present invention reduces water abandonment while increasing the power generation of cascade hydropower stations in the basin, and has good power supply guarantee and flood control capabilities.

[0049] In summary, the present invention proposes a scheduling method for cascade hydropower stations that takes into account the constraints of power supply security and flood control. It comprehensively considers the constraints of power supply security and flood control, establishes an optimization model, and realizes the optimized scheduling of the joint operation of cascade hydropower stations. It effectively regulates the water level of the hydropower station, reduces water waste, improves power generation efficiency, and ensures the power supply capacity under different water inflow conditions. At the same time, it also adjusts the degree of water level drop before the flood season by controlling the water level of centralized pumping before the flood season, and takes into account the power supply security and flood control requirements of the cascade hydropower station, thereby verifying its scientific rationality and feasibility in practical applications.

[0050] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

[0051] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A method for dispatching cascade hydropower stations taking into account the constraints between supply guarantee and flood prevention, characterized in that: The following steps are involved: S1. Analyze the power generation characteristics of cascade hydropower stations, conduct centralized water level drawdown control on reservoirs with regulatory capabilities through simulation experiments, determine the optimal drawdown time, and establish pre-flood water level drawdown time constraints; S2. With the goal of maximizing power generation and minimizing water abandonment, combined with the pre-flood water level drawdown time constraints and hydropower station infrastructure constraints, and considering power supply security constraints and flood control constraints, a coordinated optimization scheduling model for the hydropower station is constructed and solved to generate the optimal scheduling plan to achieve efficient use of water resources and maximize power generation.

2. The method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention according to claim 1, characterized in that: The water level drawdown time constraint before the flood season is: in, Indicates the time constraint of water level drawdown before flood season. Indicates the best disappearance time, 、 、 Respectively represent The hydropower station in , No. , No. The water level of the moon.

3. The method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention according to claim 2 is characterized in that: The basic constraints of a hydropower station include hydraulic constraints of upstream and downstream hydropower stations, water quantity coupling constraints, initial and final storage capacity constraints, hydropower station flow relationship constraints, water level and storage capacity relationship constraints, upper and lower limit constraints, and head constraints. The corresponding formulas are: in, represents the hydraulic constraints of upstream and downstream hydropower stations, Indicates the water flow lag between hydropower stations. Indicates the The hydropower station in Inflow flow at any moment, Indicates the The hydropower station in The power generation flow at the moment, Indicates the Moment The hydropower station and Interval flow between hydropower stations; in, represents the water quantity coupling constraint, represents the storage capacity of the first hydropower station, Indicates the The storage capacity of a hydropower station, represents the initial storage capacity of the first hydropower station, Indicates the The initial storage capacity of a hydropower station, Indicates that the first hydropower station is in Inflow flow at any moment, Indicates that the first hydropower station is in Outbound flow at any given moment, Indicates the The hydropower station in Outbound flow at any given moment, Indicates the The hydropower station in Outbound traffic at the moment; in, represents the initial and final storage capacity constraints, 、 Respectively represent The target control storage capacity of each hydropower station in the initial dispatching period, The target control storage capacity of each hydropower station at the end of the dispatch period is: Indicates the The actual controlled storage capacity of each hydropower station at the end of the dispatch period; in, represents the flow relationship constraint of the hydropower station, Indicates the Outbound flow at any given moment, Indicates the The power generation flow at the moment, Indicates the The abandoned water flow at the moment; in, represents the relationship constraint between water level and reservoir capacity, Indicates the The water level of the hydropower station at the moment, represents the relationship function between water level and reservoir capacity, Indicates the The reservoir capacity of the hydropower station at the moment; in, Indicates upper and lower limit constraints, 、 Respectively represent the minimum and maximum storage capacity of the hydropower station, 、 Represent the minimum and maximum power generation flow, Indicates the maximum water discharge rate, 、 Represent the minimum and maximum outbound flows, Indicates the The power generation at the moment, 、 Represent the minimum and maximum power generation respectively; in, represents the head constraint, Indicates the The water head of the moment, Indicates the Tailwater level at the moment.

4. The method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention according to claim 3 is characterized in that: Power supply security constraints include power generation security rate constraints and hydropower output relationship constraints, and their corresponding formulas are: in, represents the power generation guarantee rate constraint, represents the number of hydropower stations, Indicates the first The hydropower station in The power generation at the moment, Indicates the time interval, Indicates load amount; in, Represents the hydropower output constraint, Represents the hydropower generation coefficient.

5. The method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention according to claim 4 is characterized in that: Flood control constraints include water level change constraints and flood season constraints, and their corresponding formulas are: in, represents the water level change constraint, Indicates the The hydropower station in The water level at the moment, Indicates the The hydropower station in The water level at the moment, Indicates the The maximum water level change allowed for a hydropower station in one day; in, Indicates flood season constraints, Indicates the The water level of a hydropower station during flood season.

6. The method for dispatching cascade hydropower stations considering the constraints between supply guarantee and flood prevention according to claim 5, characterized in that: The coordinated optimization dispatch model of the hydropower station is: in, represents the coordinated optimization scheduling model of hydropower stations, 、 Respectively represent the minimum and maximum values, Indicates the first The hydropower station in The abandoned water flow at the time, To satisfy it, Indicates the The hydropower station in Hydropower generation capacity at the time, Indicates the total number of months in the scheduling period.

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