Cascade reservoir connection water level simulation calculation method and system based on water resource rigid constraint requirement

Abstract

The invention provides a cascade reservoir connection water level simulation calculation method based on water resource rigid constraint requirements, which comprises the following steps of: S1, judging a water level connection relation of upstream and downstream cascade reservoirs, and determining whether the connection water level needs to be subjected to simulation calculation or not; s2, rechecking the downstream water level flow relation of the upstream reservoir according to the actually measured water level flow data of the upstream and downstream cascade reservoirs, and determining a first connection water level range; s3, according to the upstream reservoir under-dam water level and flow relation, a connection water level initial value is calculated; s4, obtaining a second connection water level range according to the ecological water demand of the river reach between the upstream and downstream cascade reservoirs and the water taking demand outside the riverway; and S5, in the second connection water level range, the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs serves as the optimal connection water level of the upstream and downstream cascade reservoirs. By considering the ecological requirements of river reach water, the requirements of water taking and using users outside the river channel and the power generation benefits of the upstream and downstream reservoirs, it is ensured that the connection water level is determined more scientifically and reasonably.

Description

Technical Field

[0001] The present invention relates to the technical field of water conservancy and hydropower engineering, and specifically to a method and system for simulating and calculating water levels of cascade reservoir connections based on rigid constraints on water resources. Background Art

[0002] In implementing the rigid constraints on river basin water resources, the connection water levels of cascade reservoirs are crucial for the comprehensive management of water resources. Reasonable connection water levels can ensure the ecological flow of downstream river sections, meet navigation needs, and guarantee the safe and stable operation of hydropower stations. Currently, commonly used methods for determining connection water levels include empirical judgment, numerical simulation, and field measurement. However, these methods have certain limitations. For example, empirical judgment may be affected by subjective factors, numerical simulation requires high computational costs and expertise, and field measurement is limited by measurement conditions and time costs. Therefore, a scientific, accurate, and practical method for simulating and calculating the connection water levels of cascade reservoirs is urgently needed to meet the increasingly stringent requirements of water resource management. Summary of the Invention

[0003] The purpose of the present invention is to address the shortcomings of the existing technology and provide a cascade reservoir connection water level simulation calculation method based on the rigid constraint requirements of water resources. This method can be used to accurately determine the connection water level between cascade reservoirs to ensure the rational utilization and scheduling of water resources while meeting the requirements of ecological protection, power generation efficiency and other aspects.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for simulating and calculating the water level of cascade reservoir connections based on rigid water resource constraints includes the following steps:

[0006] Step S1: judging the connection relationship of the water levels of the upstream and downstream cascade reservoirs according to the normal water level DH0 and the dead water level DH1 of the downstream reservoir and the natural low water level UH0 below the dam of the upstream reservoir, and determining whether it is necessary to simulate and calculate the connection water level;

[0007] Step S2: reviewing the relationship between the water level and flow rate below the dam of the upstream reservoir based on the measured water level and flow rate data of the upstream and downstream cascade reservoirs to determine the first connection water level range;

[0008] Step S3, calculating the initial value of the connection water level according to the relationship between the water level and flow rate below the dam of the upstream reservoir;

[0009] Step S4: further narrowing the range of the connection water level to obtain a second connection water level range based on the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the water intake demand outside the river channel;

[0010] Step S5, within the determined connection water levels, the optimal connection water level of the upstream and downstream cascade reservoirs is taken as the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs.

[0011] Further, step S1 includes the following sub-steps:

[0012] Step S1.1, if UH0 > DH0, the upstream and downstream cascade reservoirs are not connected at all, and there is no need to calculate the connection water level;

[0013] Step S1.2, if UH0 ≤ DH1, the water levels of the upstream and downstream cascade reservoirs are completely connected, and there is no need to calculate the connection water level;

[0014] Step S1.3, if DH1 < UH0 ≤ DH0, the upstream and downstream cascade reservoirs are not completely connected, and it is necessary to perform simulation calculations for the connection water level.

[0015] Further, step S2 includes the following sub-steps:

[0016] Step S2.1, select the water level-discharge scatter points during the stable period of the upstream reservoir's outflow in recent years for fitting, and take the water level downstream of the upstream reservoir dam at the middle moment and the corresponding upstream reservoir's outflow as sample points;

[0017] Step S2.2, according to the range from the normal storage water level DH^0 of the downstream reservoir to the dead water level DH^1, select different water levels in front of the dam at a fixed elevation interval starting from DH^0. For each selected water level in front of the downstream dam, obtain the corresponding outflow of the upstream reservoir and the water level downstream of the upstream reservoir dam, plot the scatter points of the water level-discharge relationship, and fit the water level-discharge relationship upstream under the influence of different water levels of the downstream reservoir according to the scatter point distribution;

[0018] Step S2.3, analyze the backwater effect of the downstream on the water level downstream of the upstream reservoir dam, and record the water level DH

[0020] , u , u , u , , q , q (m) of the downstream reservoir in front of the dam when the water level in front of the downstream dam starts to have an obvious influence on the water level downstream of the upstream reservoir dam. The range of the first connection water level is between DH q (m - 1) and DH^0.

[0019] Further, the water level-discharge relationship upstream under the influence of different water levels of the downstream reservoir is expressed as: H u (t) = f(Q u (t), DH q (i))

[0020] where, H u (t) is the water level downstream of the upstream reservoir dam at the t-th moment, DH q (i) is the water level in front of the downstream dam at the i-th elevation interval, Q u(t) is the outflow of the upstream reservoir at time t, and f() represents the function.

[0021] Furthermore, step S3 includes:

[0022] According to the relationship between the water level and flow rate below the upstream reservoir dam H u (t) = f(Q u (t),DH q (i)) Calculate the minimum discharge flow Q of the upstream reservoir min The corresponding water level below the dam is used as the initial value of the connection water level S0, where DH q (m-1)≤S0≤DH0.

[0023] Furthermore, step S4 includes the following sub-steps:

[0024] Step S4.1: Obtain the minimum water depth H required for water ecology in the river sections between upstream and downstream cascade reservoirs through investigation or experiment. e And the minimum water depth H for users taking water outside the river ou ;

[0025] Step S4.2, take H e and H ou The larger value is taken as the minimum water depth H min ;

[0026] Step S4.3: Measure the highest elevation H of the deep point of the river 3 km below the upstream reservoir dam. L ;

[0027] Step S4.4, connect the minimum value of water level S min Should satisfy S min =H L +H min ;

[0028] Step S4.5, determine the second connection water level range as: [S min ,DH0],

[0029] Compare the initial value of the connection water level S0 and the minimum value of the connection water level S min ; If S0≤S min , then S min unchanged; if S0>S min , then S min =S0.

[0030] Furthermore, the minimum water depth H of the river section min The value range is 0.5~1.0m.

[0031] Furthermore, step S5 includes the following sub-steps:

[0032] Step S5.1, the second connection water level range [S min ,DH0] is divided into n small intervals, and the interval length is The boundary of the i-th interval is S i =S min +i·ΔS,i=0,1,2,…,n;

[0033] Step S5.2: For each interval, calculate the combined power generation of the upstream and downstream reservoirs at different water levels within the interval based on the typical power generation processes of the upstream and downstream cascade reservoirs in recent years;

[0034] Step S5.3, traverse all the divided intervals, compare the comprehensive power generation of each interval, and find the interval with the largest comprehensive power generation [S j ,S j+1j ]; The middle water level of this interval is the connection water level

[0035] Step S5.4: If higher accuracy is required, the water level interval where the maximum comprehensive power generation is located can be further subdivided, and steps S5.1-S5.3 can be repeated until a more accurate connection water level S1 is found.

[0036] Furthermore, the comprehensive power generation is:

[0037]

[0038] Among them, E i (S) is the comprehensive power generation, P up (S,t) and P down (S, t) are the power generation of the upstream reservoir and the downstream reservoir under water level, respectively, and [t1, t2] is the period of stable outflow from the upstream reservoir.

[0039] In another aspect, the present invention provides a cascade reservoir connection water level simulation calculation system based on water resource rigid constraint requirements, comprising:

[0040] The connection relationship judgment module is used to judge the connection relationship of the upstream and downstream cascade reservoir water levels based on the normal water level DH0 and dead water level DH1 of the downstream reservoir and the natural low water level UH0 under the dam of the upstream reservoir, and determine whether it is necessary to simulate and calculate the connection water level;

[0041] The first connection water level range determination module is used to review the water level and flow relationship below the upstream reservoir dam based on the measured water level and flow data of the upstream and downstream cascade reservoirs to determine the first connection water level range;

[0042] The connection water level initial value calculation module is used to calculate the connection water level initial value according to the water level and flow relationship below the dam of the upstream reservoir;

[0043] The second connection water level range determination module is used to further narrow the connection water level value range to obtain the second connection water level range based on the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the water intake demand outside the river channel;

[0044] The optimal connection water level solving module is used to determine the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs within the determined connection water level range as the optimal connection water level of the upstream and downstream cascade reservoirs.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1) Scientific and accurate. Based on a detailed analysis and fitting of the relationship between water levels and flows in cascade reservoirs, this method accurately determines the connection method for cascade reservoirs and defines the range of the connection water level. By considering the water ecological requirements of the river section, the needs of off-river water users, and the power generation benefits of upstream and downstream reservoirs, the determination of the connection water level is scientifically and rationally determined.

[0047] 2) It is practical and efficient, with a simple and easy-to-use method. The data collection and calculation process is relatively simple, and results can be quickly obtained, providing strong support for engineering practice. It can be flexibly adjusted and optimized according to actual conditions to adapt to different hydrological, geological and engineering conditions.

[0048] 3) Maximizing comprehensive benefits: This approach not only considers ecological and environmental protection requirements but also balances power generation efficiency and the rational use of water resources, maximizing comprehensive benefits. This helps optimize water resource scheduling, improve water resource utilization efficiency, and promote the sustainable development of water conservancy and hydropower projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0050] Figure 1 A flow chart of a method for simulating and calculating the water level of cascade reservoir connections based on minimum downstream flow management requirements provided by the present invention;

[0051] Figure 2 A schematic diagram of a method for simulating and calculating the water level of cascade reservoir connections based on minimum downstream flow management requirements provided by the present invention. DETAILED DESCRIPTION

[0052] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0053] Embodiment 1

[0054] The present invention provides a simulation calculation method for the connecting water levels of cascade reservoirs based on the minimum drawdown flow management requirements. Referring to Figure 1 , it includes the following steps:

[0055] Step S1: Collect basic data such as the normal storage level DH0, dead level DH1 of the downstream reservoir, and the natural low water level UH0 downstream of the upstream reservoir dam. Determine the water level connection relationship between the upstream and downstream cascade reservoirs according to the following rules:

[0056] Step S1.1: If UH0 > DH0, the upstream and downstream cascade reservoirs are completely unconnected, and there is no need to calculate the connecting water level.

[0057] Step S1.2: If UH0 ≤ DH1, the water levels of the upstream and downstream cascade reservoirs are completely connected, and there is no need to calculate the connecting water level.

[0058] Step S1.3: If DH1 < UH0 ≤ DH0, the upstream and downstream cascade reservoirs are incompletely connected, and it is necessary to perform a simulation calculation of the connecting water level.

[0059] Step S2: For incompletely connected cascade reservoirs, collect the measured water level and flow data in recent years, and review the water level - flow relationship downstream of the upstream reservoir dam. The specific method is as follows:

[0060] Step S2.1: Select the water level - flow scatter points during the stable period of the upstream reservoir's outflow in recent years for fitting. The principle for selecting sample points is that the reservoir operates stably, the flow deviation from the initial moment is within 5%, and it operates continuously for more than 3 hours. Take the tail water level and flow at the middle moment as sample points; the upstream reservoir's outflow time series is The corresponding tail water level series is where t k represents the k - th sampling moment, and l is the number of sampling points;

[0061] Step S2.2: According to the range from the normal storage level DH0 to the dead level DH1 of the downstream reservoir, select different pre - dam water levels DH q (i) (i = 0, 1, 2, 3,..., n) at a fixed elevation interval Δh starting from DH0. For each selected pre - dam water level DH of the downstream q(i) Obtain the outflow Q of the upstream reservoir at the corresponding moment u (t) and the water level H below the upstream reservoir dam u (t), plot the relationship between water level and flow rate below the dam (Q u (t k ),H u (t k )). According to the scatter distribution, a suitable mathematical model (such as polynomial fitting, exponential fitting, etc.) is used to fit the relationship between the water level and flow rate under the dam upstream under the influence of different water levels of the downstream reservoir, which can be expressed as H u =f(Q u ,DH q (i)); For example, using a polynomial fitting model where a0, a1, …, a n and b i is the fitting parameter, and n is the degree of the polynomial.

[0062] Step S2.3: Analyze the impact of downstream backwater on the water level below the upstream reservoir dam, and record the downstream reservoir dam water level DH corresponding to the point where the downstream dam water level begins to have a significant impact on the upstream reservoir dam water level. q (m). The preliminary range of the connection water level is determined to be DH q (m-1), DH0.

[0063] Step S3, connect the water level initial value calculation; according to the upstream reservoir dam water level flow relationship H u =f(Q u ,DH q (i)) Calculate the minimum discharge flow Q of the upstream reservoir min The corresponding water level below the dam is H u (i) As the initial value of the connection water level S0, it should generally meet DH q (m-1)≤S0≤DH0. The equation f(Q min ,DH qm )=H u (i), the obtained numerical solution of S0.

[0064] Step S4: Considering the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the demand for water intake outside the river channel; further narrowing the value range of the connection water level based on the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the demand for minimum water depth for water intake outside the river channel, the specific method is as follows:

[0065] Step S4.1: Obtain the minimum water depth H required for water ecology in the river sections between upstream and downstream cascade reservoirs through investigation or experiment. e And the minimum water depth H for users taking water outside the river ou ;

[0066] Step S4.2, take H e and H ou The larger value is taken as the minimum water depth H min If there are no relevant requirements, according to the specific conditions of the river section, H min The value can be 0.5~1.0m;

[0067] Step S4.3: Measure the highest elevation H of the deep point of the river 3 km below the upstream reservoir dam. L ;

[0068] Step S4.4, connect the minimum value of water level S min Should satisfy S min =H L +H min ;

[0069] Step S4.5, compare the initial value of the connection water level S0 and the minimum value of the connection water level S min ; If S0≤S min , then S min unchanged; if S0>S min , then S min =S0.

[0070] Step S5, considering the comprehensive power generation benefits of upstream and downstream cascade reservoirs to determine the connection water level;

[0071] The connection water level range determined in the above steps [S min ,DH0], the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs is used as the connection water level of the upstream and downstream cascade reservoirs. The specific method for determining it is:

[0072] Step S5.1, connect the water level range [S min ,DH0] is divided into n small intervals, and the interval length is The boundary of the i-th interval is S i =S min +i·ΔS,i=0,1,2,…,n;

[0073] Step S5.2: For each interval, calculate the comprehensive power generation of the upstream and downstream reservoirs at different water levels within the interval based on the typical power generation process of the upstream and downstream cascade reservoirs in recent years; comprehensive power generation Among them, P up and P down The power generated by the upstream and downstream reservoirs at the respective water levels can be calculated based on factors such as reservoir characteristics, hydrological data, and the performance of the power generation equipment. For example, power generation can be expressed as P = ηρgQH, where η is the power generation efficiency, ρ is the density of water, g is the acceleration due to gravity, Q is the flow rate, and H is the hydraulic head.

[0074] Step S5.3, traverse all the divided intervals, compare the comprehensive power generation of each interval, and find the interval with the largest comprehensive power generation [S j ,S j+1j ]; The middle water level of this interval is the connection water level

[0075] Step S5.4: If higher accuracy is required, the water level interval where the maximum comprehensive power generation is located can be further subdivided, and steps S5.1-S5.3 can be repeated until a more accurate connection water level S1 is found.

[0076] Example 2

[0077] This embodiment also provides a cascade reservoir connection water level simulation calculation system based on water resource rigid constraint requirements, including:

[0078] The connection relationship judgment module is used to judge the connection relationship of the upstream and downstream cascade reservoir water levels based on the normal water level DH0 and dead water level DH1 of the downstream reservoir and the natural low water level UH0 under the dam of the upstream reservoir, and determine whether it is necessary to simulate and calculate the connection water level;

[0079] The first connection water level range determination module is used to review the water level and flow relationship below the upstream reservoir dam based on the measured water level and flow data of the upstream and downstream cascade reservoirs to determine the first connection water level range;

[0080] The connection water level initial value calculation module is used to calculate the connection water level initial value according to the water level and flow relationship below the dam of the upstream reservoir;

[0081] The second connection water level range determination module is used to further narrow the connection water level value range to obtain the second connection water level range based on the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the water intake demand outside the river channel;

[0082] The optimal connection water level solving module is used to determine the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs within the determined connection water level range as the optimal connection water level of the upstream and downstream cascade reservoirs.

[0083] The above is only a preferred specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

[0084] It should be understood that parts not elaborated in detail in this specification belong to the prior art.

[0085] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of protection of the patent of the present invention. Under the guidance of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested by the present invention shall be based on the attached claims.

Claims

1. A method for simulating and calculating the water level of cascade reservoirs based on rigid constraints on water resources, characterized in that: It includes the following steps: Step S1. According to the normal storage level DH0 and dead level DH1 of the downstream reservoir, and the natural low water level UH0 downstream of the upstream reservoir dam, determine the water level connection relationship between the upstream and downstream cascade reservoirs, and determine whether it is necessary to perform a simulation calculation of the connection water level; Step S2. According to the measured water level and flow data of the upstream and downstream cascade reservoirs, review the water level - flow relationship downstream of the upstream reservoir dam, and determine the first connection water level range; Step S3. Calculate the initial value of the connection water level according to the water level - flow relationship downstream of the upstream reservoir dam; Step S4. According to the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the off - river water intake demand, further narrow the value range of the connection water level to obtain the second connection water level range; Step S5. Within the second connection water level range, take the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs as the optimal connection water level of the upstream and downstream cascade reservoirs.

2. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 1 is characterized in that: The said Step S1 includes the following sub - steps: Step S1.

1. If UH0 > DH0, then the upstream and downstream cascade reservoirs are completely not connected, and there is no need to calculate the connection water level; Step S1.

2. If UH0 ≤ DH1, then the water levels of the upstream and downstream cascade reservoirs are completely connected, and there is no need to calculate the connection water level; Step S1.

3. If DH1 < UH0 ≤ DH0, then the upstream and downstream cascade reservoirs are incompletely connected, and it is necessary to perform a simulation calculation of the connection water level.

3. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 1 is characterized in that: The said Step S2 includes the following sub - steps: Step S2.

1. Select the water level - flow scatter points during the stable outflow period of the upstream reservoir in recent years for fitting, and take the water level downstream of the upstream reservoir at the middle moment and the corresponding outflow of the upstream reservoir as the sample points; Step S2.

2. According to the range from the normal storage level DH0 to the dead level DH1 of the downstream reservoir, select different water levels in front of the dam at a fixed elevation interval starting from DH0. For each selected water level in front of the downstream dam, obtain the outflow of the upstream reservoir and the water level downstream of the upstream reservoir at the corresponding moment, plot the scatter points of the water level - flow relationship, and according to the distribution of the scatter points, use a mathematical model to fit the water level - flow relationship upstream under the influence of different water levels of the downstream reservoir; Step S2.3: Analyze the impact of downstream backwater on the water level below the upstream reservoir dam, and record the downstream reservoir dam water level DH corresponding to the point where the downstream dam water level begins to have a significant impact on the upstream reservoir dam water level. q (m), the range of the first connection water level is DH q (m-1), DH0.

4. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 3 is characterized in that: The relationship between the water level and flow rate at the upstream dam under the influence of different water levels of the downstream reservoir is expressed as: H u (t) = f(Q u (t),DH q (i)) Among them, H u (t) is the water level below the upstream reservoir dam at time t, DH q (i) is the water level in front of the downstream dam at the i-th elevation interval, Q u (t) is the outflow of the upstream reservoir at time t, and f() represents the function.

5. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 4 is characterized in that: The said Step S3 includes: According to the relationship between the water level and flow rate below the upstream reservoir dam H u (t) = f(Q u (t),DH q (i)) Calculate the minimum discharge flow Q of the upstream reservoir min The corresponding water level below the dam is used as the initial value of the connection water level S0, where DH q (m-1)≤S0≤DH0.

6. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 5 is characterized in that: The said Step S4 includes the following sub - steps: Step S4.1: Obtain the minimum water depth H required for water ecology in the river sections between upstream and downstream cascade reservoirs through investigation or experiment. e And the minimum water depth H for users taking water outside the river ou ; Step S4.2, take H e and H ou The larger value is taken as the minimum water depth H min ; Step S4.3: Measure the highest elevation H of the deep point of the river 3 km below the upstream reservoir dam. L ; Step S4.4, connect the minimum value of water level S min Should satisfy S min =H L +H min ; Step S4.5, determine the second connection water level range as: [S min ,DH0], Compare the initial value of the connection water level S0 and the minimum value of the connection water level S min ; If S0≤S min , then S min unchanged; if S0>S min , then S min =S0.

7. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 6 is characterized in that: The minimum water depth of the river section is H min The value range is 0.5~1.0m.

8. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 6 is characterized in that: The said Step S5 includes the following sub - steps: Step S5.1, the second connection water level range [S min ,DH0] is divided into n small intervals, and the interval length is The boundary of the i-th interval is S i =S min +i·ΔS,i=0,1,2,…,n; Step S5.

2. For each interval, according to the typical power generation processes of the upstream and downstream cascade reservoirs in recent years, calculate the comprehensive power generation of the upstream and downstream reservoirs at different water levels within this interval; Step S5.3, traverse all the divided intervals, compare the comprehensive power generation of each interval, and find the interval with the largest comprehensive power generation [S j ,S j+1j ]; The middle water level of this interval is the connection water level Step S5.

4. If higher accuracy is required, within the water level interval where the maximum comprehensive power generation is located, further subdivide the interval, and repeat Steps S5.1 - S5.3 until a more accurate connection water level S1 is found.

9. The method for simulating and calculating the water level of cascade reservoirs based on rigid water resource constraints according to claim 8 is characterized in that: The said comprehensive power generation is: Among them, E i (S) is the comprehensive power generation, P up (S,t) and P down (S, t) are the power generation of the upstream reservoir and the downstream reservoir under water level, respectively, and [t1, t2] is the period of stable outflow from the upstream reservoir.

10. A cascade reservoir connection water level simulation calculation system based on water resource rigidity constraint requirements, characterized in that: It includes: A connection relationship discrimination module, which is used to determine the water level connection relationship between the upstream and downstream cascade reservoirs according to the normal storage level DH0 and dead level DH1 of the downstream reservoir, and the natural low water level UH0 downstream of the upstream reservoir dam, and determine whether it is necessary to perform a simulation calculation of the connection water level; A first connection water level range determination module, which is used to review the water level - flow relationship downstream of the upstream reservoir dam according to the measured water level and flow data of the upstream and downstream cascade reservoirs, and determine the first connection water level range; The connection water level initial value calculation module is used to calculate the connection water level initial value according to the water level and flow relationship below the dam of the upstream reservoir; The second connection water level range determination module is used to further narrow the connection water level value range to obtain the second connection water level range based on the connection water level requirements under the ecological water demand of the river section between the upstream and downstream cascade reservoirs and the water intake demand outside the river channel; An optimal connection water level solving module is used to determine, within the determined connection water level range, the connection water level corresponding to the maximum comprehensive power generation benefit of the upstream and downstream cascade reservoirs as the optimal connection water level of the upstream and downstream cascade reservoirs; The cascade reservoir connection water level simulation calculation system based on water resource rigid constraint requirements is used to execute the steps in the cascade reservoir connection water level simulation calculation method based on water resource rigid constraint requirements as described in any one of claims 1-9.

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