A multi-level, multi-objective collaborative scheduling method and system for a cascade hydropower station group

Abstract

This invention discloses a multi-level, multi-objective collaborative scheduling method and system for a cascade hydropower station group. The method considers three levels: the power grid, the cascade, and the power stations, establishing optimized scheduling models for different scheduling levels at each level. Based on this, a nested coupling mechanism between the multi-level scheduling models is proposed. Through mutual nesting between different levels, collaborative optimization of different scheduling objectives of the "power grid-cascade-power station" is achieved. Different algorithms are employed for different scheduling level models to achieve efficient model solving, resulting in a refined day-ahead scheduling scheme for the cascade hydropower stations. This method, while ensuring the requirements of watershed water allocation and clean energy consumption, achieves collaborative optimization of the power generation efficiency of cascade hydropower stations, the stability of thermal power plant operation, and the operating status of hydropower units.

Description

Technical Field

[0001] This invention relates to the field of hydropower dispatching technology, and in particular to a multi-level, multi-objective collaborative dispatching method and system for a cascade hydropower station group. Background Technology

[0002] Cascade hydropower stations in river basins undertake comprehensive utilization tasks such as power generation, water supply, and flood control. They are not only an important support for the construction of new power systems under the dual-carbon goals, but also a reliable guarantee for the efficient utilization of water resources in the new era. In recent years, with the rapid development of new energy sources and increasingly refined and stringent management requirements for water resources in river basins, cascade hydropower stations face not only higher intensity and frequency of grid peak shaving and frequency regulation tasks, but also more rigid flow and water level constraints at reservoir outflows or key sections of the basin. At the same time, requirements from both water conservancy and power sectors greatly limit the optimization space for cascade hydropower scheduling and operation, resulting in problems such as large fluctuations in water levels and prolonged inefficient operation of generating units. How to better coordinate power dispatching and water dispatching tasks, further tap the potential of joint optimization space for cascade hydropower stations, and reduce the operating time of generating units under unfavorable conditions is the key to ensuring the scientific scheduling and efficient operation of cascade hydropower stations in the new era.

[0003] Short-term optimal dispatching of cascade hydropower stations typically involves dispatching decisions on a daily, hourly, or minute scale. Current research in this field, in terms of target objects, can be mainly divided into cross-regional multi-grid joint optimal dispatching, regional grid optimal dispatching, inter-station optimal dispatching, and intra-station economic operation. From the perspective of optimization objectives, the focus is primarily on single or multi-objective problems such as power generation, peak shaving, flood control, irrigation, ice control, and navigation. Under the new situation of high-proportion integration of renewable energy, how to cope with short-term wind and solar uncertainties has become a hot topic in hydropower short-term dispatching research in recent years. Current research mostly focuses on mitigating output fluctuations in complementary systems, proposing short-term dispatching models for the coordinated operation of hydropower and renewable energy. From the perspective of model solution methods, short-term optimal dispatching involves considering more and more complex hydraulic and electrical coupling constraints, making the optimization model exhibit high-dimensionality, nonlinearity, and non-convexity characteristics, which places higher demands on the accuracy and efficiency of model solution. In summary, current research on short-term scheduling of cascade hydropower mainly focuses on single-level or two-level nested studies of cascade hydropower stations in river basins, hydropower peak shaving in power grids, or economic operation within stations. Various objectives and requirements of power grids, river basins, and power stations interact and influence each other, forming an extremely complex high-dimensional spatiotemporal interconnection and coupling relationship. At present, research on multi-level scheduling of power grids, river basins, and power stations is still rare. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-level, multi-objective collaborative scheduling method and system for cascade hydropower station groups, which solves problems such as difficulty in coordinating water and power dispatch, insufficient benefits, and long-term inefficient operation of units under the conditions of high-intensity peak-shaving and frequency regulation requirements and strict water resource utilization constraints in the basin. It provides a reference for the optimal scheduling decision of cascade hydropower under complex conditions.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a multi-level, multi-objective coordinated scheduling method for a cascade hydropower station group, comprising:

[0007] A hydropower-thermal power synergistic optimization model with the objective of minimizing the average distance between thermal power loads was established and solved to obtain the total power output process of cascade hydropower stations.

[0008] With the shape of the power output process of the cascade hydropower stations as a constraint, an inter-station optimization model of the cascade hydropower stations with the objective function of maximizing the power generation of the cascade hydropower stations is established and solved to obtain the power output process of each hydropower station.

[0009] With the output of each hydropower station as a constraint, a load distribution model within the hydropower station is established and solved with the objective function of minimizing the water consumption for power generation by the hydropower station units, so as to obtain the output process of each unit of each hydropower station.

[0010] Furthermore, the establishment of a hydropower-thermal power synergistic optimization model with the objective of minimizing the average distance between thermal power loads includes:

[0011] The objective function is defined as follows:

[0012] ;

[0013] in, The objective function of the hydropower-thermal power synergistic optimization model is... The time period number. =1,2,… , The total number of scheduling periods. express Thermal power load during certain periods;

[0014] The objective function must satisfy the following constraints:

[0015] A1. Power balance constraints:

[0016] ;

[0017] in, for Grid load during the time period , , They represent The combined output of hydropower, wind power, and solar power during the specified time period;

[0018] A2. Constraints on dispatchable power capacity of hydropower stations:

[0019] ;

[0020] in, The dispatchable electricity for cascade hydropower stations The duration of the scheduling period;

[0021] A3. Output Constraints:

[0022] ; ;

[0023] in, , These are the lower and upper limits of thermal power output, respectively. , These are the lower and upper limits of hydropower output, respectively.

[0024] A4. Climbing ability constraint:

[0025] ;

[0026] in, This represents the maximum climbing capacity of thermal power plants.

[0027] A5. Spinning reserve capacity constraint:

[0028] ;

[0029] in, For hydroelectric rotating reserve capacity, For rotating reserve capacity of thermal power plants;

[0030] A6. Constraints on the number of generating units in operation at cascade hydropower stations:

[0031] ;

[0032] in, for Number of generating units in cascade hydropower stations during a given time period. The maximum and minimum number of generating units that can be operated at a cascade hydropower station.

[0033] Furthermore, the establishment of the inter-station optimization model for cascade hydropower stations with the objective function of maximizing the power generation of the cascade hydropower stations includes:

[0034] The objective function is established as follows:

[0035] ;

[0036] in, The objective function is the optimization model between cascade hydropower stations. Time period number =1,2,…, , The total number of scheduling periods. This refers to the serial number of the hydropower station. =1,2,…, , For the number of hydroelectric power stations, for Periodic hydroelectric power station contribution;

[0037] The objective function must satisfy the following constraints:

[0038] B1. Water level constraints of cascade hydropower stations:

[0039] ;

[0040] in, This refers to the planned water outflow from the reservoir of the leading hydropower station. for Periodic hydroelectric power station The average outflow from the reservoir, and They are respectively =1 and =T-time hydropower station The reservoir water level and They represent hydroelectric power stations Initial and final water level control requirements during the scheduling period;

[0041] B2. Load shape constraint:

[0042] ;

[0043] in, The load shape characteristics of the cascade hydropower stations are determined based on the solution results of the hydropower-thermal power synergistic optimization model;

[0044] B3. Water balance constraint:

[0045] ;

[0046] in, for Periodic hydroelectric power station Reservoir capacity for Periodic hydroelectric power station Average inbound flow for Periodic hydroelectric power station The outflow rate, for Periodic hydroelectric power station Water loss due to evaporation and seepage from the reservoir;

[0047] B4. Hydropower station output, power generation flow, discharge flow, and upper and lower limits of reservoir water level:

[0048] ;

[0049] in, , Hydropower stations Upper and lower limits of output for Periodic hydroelectric power station Power generation flow, , Hydropower stations Upper and lower limits of power generation flow rate , Hydropower stations The upper and lower limits of the discharge flow. for Periodic hydroelectric power station The reservoir water level , Hydropower stations Upper and lower limits of reservoir water level;

[0050] B5. Hydraulic connection of cascade hydropower stations:

[0051] ;

[0052] in, for Periodic hydroelectric power station Average outbound flow For hydroelectric power station Outflow reaches hydropower station The time required for Periodic hydroelectric power station To the hydroelectric power station Interval flow between;

[0053] B6. Water level fluctuation constraints:

[0054] ;

[0055] in, Hydropower stations in adjacent time periods Maximum permissible fluctuation in water level;

[0056] B7. Spinning reserve capacity constraints of hydropower stations:

[0057] ;

[0058] in, For hydroelectric power station Rotating reserve capacity, For hydroelectric power station The rotating reserve capacity factor.

[0059] Furthermore, the establishment of the load allocation model within the hydropower station with the objective function of minimizing the water consumption for power generation by the hydropower station units includes:

[0060] The objective function is established as follows:

[0061] ;

[0062] in, Let be the objective function of the load allocation model within the hydropower station. The time period number. =1,2,…, , The total number of scheduling periods. This refers to the serial number of the hydropower station. =1,2,…, , For the number of hydroelectric power stations, For hydroelectric power station Unit serial number =1,2,…, , For hydroelectric power station Number of medium-sized generating units Indicates in Periodic hydroelectric power station medium-sized units The power generation flow rate;

[0063] The objective function must satisfy the following constraints:

[0064] C1. Power balance constraints:

[0065] ;

[0066] in, Indicates in Periodic hydroelectric power station medium-sized units contribution;

[0067] C2. Unit output and upper / lower limits for unit power generation flow:

[0068] ;

[0069] in, , Hydropower stations medium-sized units Upper and lower limits of output , Hydropower stations medium-sized units Upper and lower limits for power generation flow;

[0070] C3. Unit vibration zone constraints:

[0071] ;

[0072] in, and They are respectively Periodic hydroelectric power station medium-sized units Minimum and maximum output, , Hydropower stations medium-sized units The The upper and lower limits of the output power in each vibration zone;

[0073] C4. Minimum start-up and shutdown duration constraint for the unit:

[0074] ;

[0075] in, for Periodic hydroelectric power station medium-sized units The running status, This indicates that the unit is powered on; otherwise... ; , For hydroelectric power station medium-sized units Minimum downtime and minimum startup time; For unit start-up operation variables, express Periodic hydroelectric power station medium-sized units The power-on operation was performed; otherwise... ; This is a variable for unit shutdown operations. express Periodic hydroelectric power station medium-sized units The shutdown operation was performed; otherwise... ;

[0076] C5. Constraint on the number of generating units in operation:

[0077] ;

[0078] in, for Periodic hydroelectric power station Number of medium-sized generating units in operation. For hydroelectric power station Maximum and minimum number of machines that can be started.

[0079] Furthermore, the method also includes:

[0080] During the solution process, the maximum power generation of the cascade hydropower stations obtained from the inter-station optimization model is used as the dispatchable power of the cascade hydropower stations at the grid level and fed back to the hydropower-thermal power co-optimization model. With this as a constraint, the hydropower-thermal power co-optimization model is optimized and solved, the total output process of the cascade hydropower stations is updated, and the load shape characteristics of the cascade hydropower stations are extracted and transferred to the inter-station optimization model.

[0081] The optimization model of the cascade hydropower stations is optimized by taking the load shape characteristics of the cascade hydropower stations as constraints, optimizing the output of each hydropower station in the cascade, and feeding back the maximum power generation of the cascade hydropower stations to the hydropower-thermal power collaborative optimization model.

[0082] This cycle repeats;

[0083] The method further includes:

[0084] During the solution process, the output of each cascade hydropower station obtained from the inter-station optimization model is fed back to the load distribution model within the hydropower station. Using this as a constraint, the load distribution model within the station is optimized to obtain the output of each unit. The power generation flow of each hydropower station is then fed back to the inter-station optimization model of the cascade hydropower station. The power generation flow of each hydropower station is the sum of the power generation flow of each unit in each hydropower station.

[0085] The optimization model between cascade hydropower stations is optimized and solved with the power generation flow of each hydropower station as a constraint. The output of each cascade hydropower station is updated and fed back to the load distribution model within the hydropower station.

[0086] This cycle continues.

[0087] Furthermore, the hydropower-thermal power synergistic optimization model is solved, including:

[0088] S11, Based on the load forecast for the next day New energy power forecast Determine the equivalent load for the next day , ;

[0089] S12. The total power generation of the cascade hydropower stations in the previous dispatch cycle. As the initial power source, the load command for the cascade hydropower stations is obtained using a successive load shedding method. ;

[0090] S13, Load assessment command for cascade hydropower stations Does it meet the output constraint? If not, consider the thermal power plant's ramp-up capability. The output process of the cascade hydropower stations during this period and the nearby periods is adjusted, and the adjustment amount is spread out from the other periods until the load command of the cascade hydropower stations fully meets the output constraints.

[0091] S14. Extracting the load shape characteristics of cascade hydropower stations based on the following formula. This feedback is fed back to the optimization model between the cascade hydropower stations to optimize the dispatchable power capacity of the cascade hydropower stations. ,

[0092] ;

[0093] S15. Determine the increase in dispatchable power capacity of cascade hydropower stations. Does it meet the preset accuracy? If satisfied, the iteration ends, and the output processes of thermal power, hydropower stations at each stage, and generating units within each hydropower station are output. If not satisfied, the dispatchable power of the hydropower stations at each stage is updated, and the process returns to step S12. The iteration continues until the increase in the dispatchable power of the hydropower stations at each stage meets the preset accuracy.

[0094] Furthermore, the optimization model between the cascade hydropower stations is solved, including:

[0095] S211, Based on the comprehensive output coefficient of each hydropower station Helong Hydropower Station Outflow Plan Estimate the total power generation of each hydropower station during the dispatch period ;

[0096] S212, Based on the total power generation of each hydropower station during the dispatch period and the load shape characteristics of hydropower stations The power output process lines of each hydropower station were generated using a synchronous peak-shaving strategy, as follows:

[0097] ;

[0098] S213. Determine the start-up plan for each hydropower station unit based on the principle of minimum number of units required to be started. And correct it according to the unit start-up and shutdown constraints;

[0099] S214. Taking the output of each hydropower station as a constraint, and combining the start-up plans of each hydropower station unit. Based on the load distribution model within the hydropower station, the power generation flow of each generating unit is calculated, thereby obtaining the power generation flow of the hydropower station. Water level process and the process of discharge flow ;

[0100] S215. Determine whether the total water volume / final water level of the hydropower station meets the water level constraints of the cascade hydropower stations. If not, determine the water volume / water level deviation according to a certain step size. Adjust the total power output of the hydropower station during the scheduling period, return to S212, recalculate, until all the cascade hydropower stations have been calculated, and obtain the initial solution of the power output of each cascade hydropower station.

[0101] S221. Decompose the scheduling cycle with the unit start-up and shutdown time as the optimization step size, and combine every two optimization time periods after the start time into a new sub-problem.

[0102] S222, Discretize the reservoir capacity status of each hydropower station between optimization steps into... The data are combined to form a set of reservoir capacity statuses for cascade hydropower stations. Calculate and optimize step size water volume limit ,in, For hydroelectric power station Storage capacity status ;

[0103] S223. Determine the feasible number of generating units to be started at each hydropower station in the cascade under different water volume constraints. The cascade hydropower station commissioning scheme , For hydroelectric power station Storage capacity status The number of machines started;

[0104] S224. The sum of the initial output solutions of each hydropower station within the optimization period is distributed among the hydropower stations according to their operating capacity. The power generation flow is determined using a load distribution model within the hydropower station. And calculate whether the water volume limit is met. If the water volume limit is not met, the output process will be adjusted according to the load shape until the water volume limit calculation accuracy is met.

[0105] S225. Combine the start-up schemes in the two optimization time period start-up scheme sets one by one, store the schemes that meet the unit start-up and shutdown constraints into the sub-problem start-up combination scheme set, and store the corresponding output process.

[0106] S231. Connect the sub-problems according to the unit start-up and shutdown constraints to form the set of start-up combination schemes, and search for the scheme with the maximum power generation in order.

[0107] S232. Shift the starting time period backward by one optimization step, return to step S221 to reallocate the subproblems and solve them;

[0108] S233, iterate in a loop until the increase in power is less than the preset precision.

[0109] Furthermore, the load distribution model within the hydropower station is solved, including:

[0110] The dynamic programming algorithm is used to solve the load distribution model within the hydropower station.

[0111] This invention also provides a multi-level, multi-objective collaborative scheduling system for a cascade hydropower station group, characterized in that it is used to implement the aforementioned multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group, the system comprising:

[0112] The power grid hierarchical scheduling module is used to establish and solve a hydropower-thermal power coordinated optimization model with the objective of minimizing the average distance between thermal power loads, and obtain the total output process of cascade hydropower stations.

[0113] The cascade-level scheduling module is used to establish and solve an inter-station optimization model of cascade hydropower stations with the shape of the power output process of cascade hydropower stations as a constraint and the objective function of maximizing the power generation of cascade hydropower stations, so as to obtain the power output process of each hydropower station.

[0114] The power station hierarchical scheduling module is used to establish and solve a load distribution model within a hydropower station with the output of each hydropower station as a constraint and the objective function of minimizing the water consumption of the hydropower station units, so as to obtain the output process of each unit of each hydropower station.

[0115] The beneficial effects of this invention are as follows:

[0116] (1) This invention classifies various scheduling objectives and requirements into three levels: power grid, cascade and power station. It establishes optimized scheduling models for different levels of power grid, cascade and power station, and proposes a multi-level multi-objective collaborative optimization mechanism. By nesting different levels, it solves problems such as difficulty in coordinating water and electricity scheduling, insufficient benefits, and long-term inefficient operation of units under the constraints of high-intensity peak and frequency regulation requirements and rigid water volume scheduling in the basin.

[0117] (2) This invention uses different optimization algorithms to solve the scheduling models at different levels, based on the objective constraint forms and computational scale of different scheduling models, thus solving the problem of solving the multi-level, multi-objective optimization scheduling model of "power grid-cascade-power station" for cascade hydropower stations. Attached Figure Description

[0118] Figure 1 Here is a flowchart of a multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group provided in Embodiment 1 of the present invention;

[0119] Figure 2 This is the framework of the multi-level, multi-objective optimization scheduling model of "power grid-cascade-power station" in this invention;

[0120] Figure 3 This is the multi-level nested optimization mechanism in this invention;

[0121] Figure 4This is a flowchart of the staggered stepwise optimization algorithm in this invention. Detailed Implementation

[0122] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0123] Example 1

[0124] This embodiment provides a multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group. (See also...) Figure 1 ,include:

[0125] A hydropower-thermal power synergistic optimization model with the objective of minimizing the average distance between thermal power loads was established and solved to obtain the total power output process of cascade hydropower stations.

[0126] With the shape of the power output process of the cascade hydropower stations as a constraint, an inter-station optimization model of the cascade hydropower stations with the objective function of maximizing the power generation of the cascade hydropower stations is established and solved to obtain the power output process of each hydropower station.

[0127] With the output of each hydropower station as a constraint, a load distribution model within the hydropower station is established and solved with the objective function of minimizing the water consumption for power generation by the hydropower station units, so as to obtain the output process of each hydropower station unit.

[0128] In this embodiment, a hydropower-thermal power co-optimization model is established with the objective of minimizing the average distance between thermal power loads. The objective function is:

[0129] ;

[0130] in, The objective function of the hydropower-thermal power synergistic optimization model is... The time period number. =1,2,… , The total number of scheduling periods. express Thermal power load during specific time periods.

[0131] The objective function mentioned above must satisfy the following constraints: power balance, dispatchable power capacity of hydropower stations, output, ramp-up capability, spinning reserve capacity, and number of generating units in operation of cascade hydropower stations.

[0132] In this embodiment, an inter-station optimization model for cascade hydropower stations is established with the objective function of maximizing the power generation of the cascade hydropower stations. The objective function is:

[0133] ;

[0134] in, The objective function is the optimization model between cascade hydropower stations. Time period number =1,2,…, , The total number of scheduling periods. This refers to the serial number of the hydropower station. =1,2,…, , For the number of hydroelectric power stations, for Periodic hydroelectric power station of effort.

[0135] The above objective function must satisfy the following constraints: water level constraints of cascade hydropower stations, load shape constraints, water balance constraints, power output, power generation flow, discharge flow, upper and lower limits of reservoir water level constraints, hydraulic connection constraints of cascade hydropower stations, water level fluctuation constraints, and spinning reserve capacity constraints of hydropower stations.

[0136] In this embodiment, a load allocation model within a hydropower station is established with the objective function of minimizing the water consumption for power generation by the hydropower station units. The objective function is:

[0137] ;

[0138] in, The objective function for the load allocation model within a hydropower station is [function name]. The time period number. =1,2,…, , The total number of scheduling periods. This refers to the serial number of the hydropower station. =1,2,…, , For the number of hydroelectric power stations, For hydroelectric power station Unit serial number =1,2,…, , For hydroelectric power station Number of medium-sized generating units Indicates in Periodic hydroelectric power station medium-sized units The power generation flow.

[0139] The above objective function must satisfy: power balance constraints, upper and lower limits of unit output and unit power generation flow, unit vibration zone constraints, minimum start-up and shutdown duration constraints, and number of units in operation constraints.

[0140] Example 2

[0141] As a specific implementation of Example 1, this example provides a multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group. For details, please refer to [link to example 1]. Figure 2 ,include:

[0142] (1) At the power grid level, a hydropower-thermal power synergistic optimization model is established with the goal of minimizing the average distance between thermal power loads. Considering the requirements for safe operation of the power grid and the consumption of clean energy, the equivalent load process after removing wind and solar power output from the power grid load is smoothed using cascade hydropower stations. This generates the range of total hydropower output, the shape of the total output process, and the required number of generating units to be in operation for each time period. Specifically:

[0143] The hydropower-thermal power synergistic optimization model aims to minimize the average load distance of thermal power, using full absorption of new energy sources as the boundary condition. It smooths the thermal power output process by optimizing the hydropower output process. The objective function is expressed as:

[0144] (1)

[0145] In the formula, The objective function of the hydropower-thermal power synergistic optimization model is... The time period number. =1,2,… ; This represents the total number of scheduling periods; express Thermal power load during the time period, kW.

[0146] The model must satisfy the following constraints:

[0147] A1. Power balance constraints:

[0148] (2)

[0149] In the formula, for Grid load during the time period, kW; , , They represent The combined output of hydropower, wind power, and solar power during the period is kW.

[0150] A2. Dispatchable power constraints of hydropower stations

[0151] (3)

[0152] In the formula: The dispatchable power of the cascade hydropower stations is expressed in kW·h. This refers to the duration of the scheduling period.

[0153] A3. Output Constraints

[0154] ; (4)

[0155] In the formula: , These represent the lower and upper limits of thermal power output, in kW; , These represent the lower and upper limits of hydropower output, respectively, in kW.

[0156] A4. Climbing ability constraints

[0157] (5)

[0158] In the formula: This represents the maximum ramping capability of thermal power plants, in kW.

[0159] A5. Spinning Reserve Capacity Constraints

[0160] ; (6)

[0161] In the formula: The rotating reserve capacity for hydropower is kW; The rotating reserve capacity for thermal power plants is in kW.

[0162] A6. Constraints on the Number of Generating Units in Operation of Cascade Hydropower Stations

[0163] To meet the grid phase regulation requirements under large-scale renewable energy grid integration, calculations and analyses based on measured parameters, operating limits, and overload capacity of power equipment determine that the number of generating units in a cascade hydropower station must meet the following operational control principles:

[0164] (7)

[0165] In the formula: The number of cascade hydropower stations in operation during time period t. The maximum and minimum number of generating units that can be operated at a cascade hydropower station.

[0166] It should be noted that in this level, the grid load, wind power aggregate output, solar power aggregate output, dispatchable hydropower, hydropower output limit, thermal power ramp-up capability, and spinning reserve capacity are known quantities, while the process of aggregating hydropower and thermal power output is an unknown quantity for decision-making in this level of the model.

[0167] (2) At the cascade level, an inter-station optimization model for cascade hydropower stations is established with the objective function of maximizing the power generation of the cascade hydropower stations. Considering the power generation characteristics of each hydropower station and the hydraulic connection between stations, the power output process of each hydropower station is obtained by optimizing the load distribution and water storage and release strategies of each hydropower station, as follows:

[0168] The optimization model for cascade hydropower stations uses maximizing the power generation of each station as the objective function, and uses the water volume / level requirements of each station and the total load shape of the cascade hydropower stations as boundaries to optimize the power output process of each station. The objective function is expressed as:

[0169] (8)

[0170] In the formula: The objective function is the optimization model between cascade hydropower stations. Time period number =1,2,…, ; This represents the total number of scheduling periods; This refers to the serial number of the hydropower station. =1,2,…, , The number of hydroelectric power stations; for Periodic hydroelectric power station The output power is kW.

[0171] The above objective function must satisfy the following constraints:

[0172] B1. Utilization Rules for Cascade Hydropower Stations

[0173] To meet the needs of comprehensive utilization, the head reservoir of a cascade hydropower station must meet the total outflow requirements during the scheduling period; the downstream daily regulating hydropower stations must maintain stable water levels and meet the initial and final water level constraints within the day.

[0174] (9)

[0175] In the formula, For the planned outflow of water from the headwater hydropower station, m 3 ; for Periodic hydroelectric power station Average outflow from the reservoir, m 3 / s; express Periodic hydroelectric power station Reservoir water level, m and for =1 and =T-time hydropower station The reservoir water level and They represent hydroelectric power stations The initial and final water level control requirements during the scheduling period are in meters (m).

[0176] B2. Load Shape Constraints

[0177] To meet the requirements for renewable energy consumption, the load commands undertaken by cascade hydropower stations exhibit specific variation patterns. Therefore, load shape curves are used to constrain the output process of cascade hydropower stations.

[0178] (10)

[0179] In the formula, The load shape characteristics of cascade hydropower stations are determined by the load process of cascade hydropower stations in the power grid load allocation scheme.

[0180] B3. Water Balance Constraints

[0181] (11)

[0182] In the formula: for Periodic hydroelectric power station Reservoir capacity, m 3 ; for Periodic hydroelectric power station Average inbound flow, m 3 / s; for Periodic hydroelectric power station The outflow rate, m 3 / s; for Periodic hydroelectric power station Reservoir evaporation and seepage losses, m 3 It is generally related to the water area of ​​the reservoir.

[0183] B4. Hydropower station output, power generation flow, discharge flow, and upper and lower limits of reservoir water level:

[0184] (12)

[0185] In the formula: for Periodic hydroelectric power station The output power, kW; , Hydropower stations Upper and lower limits of output, kW; for Periodic hydroelectric power station The power generation flow, m 3 / s; , For hydroelectric power station Upper and lower limits of power generation flow, m 3 / s; for Periodic hydroelectric power station The outflow rate, m 3 / s; , For hydroelectric power station The upper and lower limits of the discharge flow, m 3 / s, for Periodic hydroelectric power station The reservoir water level, in meters; , For hydroelectric power station Upper and lower limits of reservoir water level, in meters (m).

[0186] B5. Hydraulic connection of cascade hydropower stations

[0187] (13)

[0188] In the formula: for Periodic hydroelectric power station Average outbound flow, m 3 / s; For hydroelectric power station Outflow reaches hydropower station The required time, in hours; for Periodic hydroelectric power station To the hydroelectric power station The flow rate between the intervals, m 3 / s.

[0189] B6. Water level fluctuation constraints

[0190] (14)

[0191] In the formula: Hydropower stations in adjacent time periods Maximum permissible water level fluctuation, in meters (m).

[0192] B7. Spinning Reserve Capacity Constraints of Hydropower Stations

[0193] (15)

[0194] In the formula: For hydroelectric power station Rotating reserve capacity, kW; For hydroelectric power station The rotating reserve capacity factor.

[0195] It should be noted that in this level, the planned outflow of water from the head reservoir, the initial and final water levels of the downstream reservoirs during the scheduling period, the flow delay between the cascade hydropower stations, the allowable fluctuation of water levels at each power station, the power output of the hydropower station, the power generation flow, the upper and lower limits of the reservoir water levels, and the reserve capacity of each power station are known values, while the power output process of each hydropower station is the decision variable.

[0196] It should be noted that by optimizing the objective function at this level, the output of each hydropower station is obtained, and multiplying it by time gives the power generation.

[0197] (3) At the power station level, an in-station load distribution model is established with the objective function of minimizing the water consumption for power generation of the hydropower station units. Considering the safe operation of the units and the requirement to reduce the water consumption rate for power generation, the operating conditions of the units are optimized to obtain the output process of each unit in different hydropower stations. The specific process is as follows:

[0198] The load distribution model within a hydropower station uses the minimum water consumption for power generation by the hydropower station units as the objective function and the safe operation of the units as the boundary condition to optimize the output process of each unit in different hydropower stations. The objective function is expressed as:

[0199] (16)

[0200] In the formula, The objective function for the load allocation model within a hydropower station is [function name]. The time period number. =1,2,…, ; This represents the total number of scheduling periods; This refers to the serial number of the hydropower station. =1,2,…, , The number of hydroelectric power stations; For hydroelectric power station Unit serial number =1,2,…, , For hydroelectric power station Number of medium-sized generating units; Indicates in Periodic hydroelectric power station medium-sized units The power generation flow, m 3 / s.

[0201] The objective function must satisfy the following constraints:

[0202] C1, Power Balance Constraints

[0203] (17)

[0204] In the formula, Indicates in Periodic hydroelectric power station medium-sized units The output power is kW.

[0205] C2. Upper and lower limits of unit output and unit power generation flow rate constraints

[0206] (18)

[0207] In the formula: , Hydropower stations medium-sized units Upper and lower limits of output, kW; , Hydropower stations medium-sized units Upper and lower limits of power generation flow, m 3 / s.

[0208] C3. Unit vibration zone constraints

[0209] (19)

[0210] In the formula: , They are respectively Periodic hydroelectric power station medium-sized units Minimum and maximum output, kW , Hydropower stations medium-sized units The The upper and lower limits of the output power of each vibration zone, in kW.

[0211] C4. Minimum start-up and shutdown duration constraint for the unit

[0212] (20)

[0213] In the formula: for Periodic hydroelectric power station medium-sized units The running status, This indicates that the unit is powered on; otherwise... ; , For hydroelectric power station medium-sized units Minimum downtime and minimum startup time; For unit start-up operation variables, express Periodic hydroelectric power station medium-sized units The power-on operation was performed; otherwise... ; This is a variable for unit shutdown operations. express Periodic hydroelectric power station medium-sized units The shutdown operation was performed; otherwise... .

[0214] C5. Unit operating limit constraint

[0215] ;(twenty one)

[0216] In the formula: for Periodic hydroelectric power station Number of medium-sized generating units in operation. For hydroelectric power station Maximum and minimum number of machines that can be started.

[0217] It should be noted that in this level, the power output of the hydropower station, the upper and lower limits of the unit's power output, the upper and lower limits of the unit's power generation flow, the shortest start-up and shutdown duration of the unit, the vibration zone range of each unit, and the constraints on the number of units in operation are known quantities, while the power output of each unit in the hydropower station is the decision variable.

[0218] It should be noted that by optimizing the objective function at this level, the power generation flow of each unit is obtained, and multiplying it by time gives the water consumption for power generation.

[0219] (4) A nested coupling mechanism is proposed among the different levels of optimization scheduling models of "power grid-cascade-power station" to achieve coordinated optimization of different scheduling objectives. See [link to relevant documentation]. Figure 3 The specific implementation method is as follows:

[0220] The "grid-cascade" coupling mechanism: The grid level receives the maximum power generation of the cascade hydropower stations from the cascade level based on the inter-station optimization model of the cascade hydropower stations, and uses this as the dispatchable power of the cascade hydropower stations at the grid level. The power output process of the hydropower station is obtained by solving the power grid hierarchical model. Extracting the load shape characteristics of hydropower stations And pass it back to the hierarchical level as a constraint;

[0221] The cascade hydropower stations integrate load shape characteristics and constraints such as water volume / level to optimize the power output process of each cascade hydropower station with the goal of maximizing power generation, and feed the power generation information of the cascade hydropower stations back to the power grid level.

[0222] It should be noted that the power generation information of the cascade hydropower stations is the sum of the maximum power generation of each cascade hydropower station.

[0223] "Cascade-Power Station" Coupling Mechanism: To simultaneously satisfy the load shape constraints and water volume / level constraints in the cascade levels, the model solves for the power output process of each power station in the cascade. A trial calculation involving "electricity-based water supply" is required. The calculation process is as follows: Given an initial power output scheme for each cascade power station that satisfies the cascade load shape, determine the water consumption and water level process using "electricity-based water supply." Calculate the deviation from the given water volume / water level constraints. Adjust the power output scheme for each cascade power station according to the load shape constraints based on the magnitude of the deviation, until both the load shape and water volume / water level constraints are simultaneously met. Output the power output process for each cascade power station. The "electricity-based water supply" process is completed at the power station level, with each level acting on load instructions from its respective cascade hydropower station. The power output of each unit is obtained by solving the load distribution model within the station, and the power generation flow of each hydropower station is calculated. Feedback is sent back to the hierarchical levels.

[0224] It should be noted that the load command for each cascade hydropower station refers to the output of each hydropower station in the cascade, calculated at each cascade level.

[0225] It should be noted that the power generation flow of each hydropower station is the sum of the power generation flow of each unit in the hydropower station.

[0226] (5) Different optimization algorithms are used to solve the multi-level multi-objective scheduling model, and the cascade hydropower optimization scheduling strategy for the multi-level scheduling needs of power grid, cascade, and power station is obtained.

[0227] The scheduling models at different levels—grid, cascade, and power plant—have different objective constraints and computational scales, and therefore require different model-solving algorithms. This embodiment employs different optimization algorithms to solve the scheduling models at each level. First, a heuristic algorithm is used for multi-source collaborative optimization at the grid level; an interleaved stepwise optimization algorithm is proposed to collaboratively optimize and generate inter-station load allocation schemes at the cascade level; and a dynamic programming algorithm is used to complete the inter-unit allocation of load commands at the power plant level. Details are as follows:

[0228] S1. A heuristic algorithm is used to solve the hydropower-thermal power co-optimization model, and multi-source co-optimization is performed at the power grid level, as follows:

[0229] S11, Based on the load forecast for the next day New energy power forecast Determine the equivalent load for the next day ;

[0230] S12. The total power generation of the cascade hydropower stations in the previous dispatch cycle. As the initial power source, the load command for the cascade hydropower stations is obtained using a successive load shedding method. ;

[0231] S13. Modify the load command for cascade hydropower stations.

[0232] If the load command of the cascade hydropower station If the output constraints are not met, the power output process of the cascade hydropower stations in the period and the nearby period will be corrected considering the ramping capacity of thermal power plants. The correction amount will be spread out by the remaining periods until all load commands of the cascade hydropower stations meet the output constraints.

[0233] S14. Use formula (22) to extract the load shape characteristics of cascade hydropower stations. Input the cascade level to obtain the optimized dispatchable power of the cascade hydropower stations. .

[0234] ;(twenty two)

[0235] S15. Determine the increase in dispatchable power capacity of cascade hydropower stations. Does it meet the accuracy requirements? If satisfied, the iteration ends, and the output processes of thermal power, each cascade power station, and each unit within the hydropower station are output. If not satisfied, the dispatchable power of the cascade hydropower stations is updated, and the process returns to step S12. The iteration continues until the increase in the dispatchable power of the cascade hydropower stations meets the accuracy requirements.

[0236] S2. An alternating successive optimization algorithm is used to solve the optimization model between cascade hydropower stations.

[0237] Optimizing load allocation between cascade hydropower stations requires consideration of numerous spatiotemporal coupling constraints, such as load characteristic constraints, water volume / level constraints, and unit start-up and shutdown times, which exacerbates the difficulty of optimization calculations. This embodiment improves upon the stepwise optimization algorithm by proposing an interleaved stepwise optimization algorithm, such as... Figure 4 As shown, it mainly includes two aspects:

[0238] A nested approach to handling time- and spatial coupling constraints is employed: Using a step-by-step optimization principle, the scheduling cycle is decomposed into optimization steps based on unit start-up and shutdown times. Every two optimization periods are combined into new sub-problems, and each sub-problem is assigned a water quantity constraint to satisfy the power station operation requirements and unit start-up and shutdown time constraints at different time scales. Spatial coupling constraints such as the load shape of the cascade hydropower stations are calculated using a power-to-water ratio method within each optimization step.

[0239] Joint optimization of unit combination and water allocation: Optimized water allocation can improve the head efficiency of each power station by changing the order of water storage and release, while optimized unit combination can improve unit operating efficiency through inter-station capacity compensation. However, the stepwise optimization of the water allocation problem requires finding the optimal water allocation path between the two stages, and solving the unit combination problem requires generating and connecting the set of unit operating states at each stage. Therefore, the joint optimization of water allocation and unit combination requires staggered iteration. First, the scheduling period is decomposed into a two-stage sub-problem with water constraints, and the unit operating scheme during the scheduling period is solved. Then, the initial time period is shifted backward by one optimization step, the water constraint sub-problem is re-allocated and solved, and the process is iterated until the computational accuracy is met.

[0240] The solution steps of the staggered successive optimization algorithm are as follows:

[0241] S21. Initial Solution Generation Strategy

[0242] S211, Based on the comprehensive output coefficient of each hydropower station Helong Hydropower Station Outflow Plan Estimate the total power generation of each hydropower station during the dispatch period ;

[0243] S212, Based on the total power generation of each hydropower station during the dispatch period and the load shape characteristics of hydropower stations The power output process lines of each hydropower station are generated by adopting a synchronous peak-shaving strategy, as shown in equation (23).

[0244] ;(twenty three)

[0245] S213. Determine the start-up plan for each hydropower station unit based on the principle of minimum number of units required to be started. And correct it according to the unit start-up and shutdown constraints;

[0246] S214. Taking the output of each hydropower station as a constraint, and combining the start-up plans of each hydropower station unit. The power generation flow of each unit is calculated based on the load distribution model within the station, thereby obtaining the power generation flow of the hydropower station. Water level process and the process of discharge flow ;

[0247] S215. If the total water volume / final water level of the power station does not meet the comprehensive utilization conditions of the cascade hydropower station, the deviation of water volume / water level shall be calculated according to a certain step size. Adjust the total power output of the hydropower station during the scheduling period, return to S212, recalculate, until all the cascade hydropower stations have been calculated, and obtain the initial solution of the power output of each cascade hydropower station;

[0248] S22. Stepwise optimization of subproblem solving

[0249] S221. Decompose the scheduling cycle into optimization periods based on the unit start-up and shutdown times. After the start time, combine every two optimization periods into a new sub-problem.

[0250] S222, Discretize the reservoir capacity status of each hydropower station during the optimization period as follows: The data are combined to form a set of reservoir capacity statuses for cascade hydropower stations. Calculate and optimize water volume limits during the optimal period ,in, For hydroelectric power station Storage capacity status ;

[0251] S223. Determine the feasible number of generating units to be started at each hydropower station in the cascade under different water volume constraints. The cascade hydropower station commissioning scheme , For hydroelectric power station Storage capacity status The number of machines started;

[0252] S224. The sum of the initial output solutions of each hydropower station within the optimization period is distributed among the hydropower stations according to their operating capacity, and the power generation flow is determined using an intra-station load distribution model. And calculate whether the water volume limit is met. If the water volume limit is not met, adjust the output process according to the load shape until the water volume limit calculation accuracy is met.

[0253] S225. Combine the start-up schemes in the two optimization time period start-up scheme sets one by one, store the schemes that meet the unit start-up and shutdown constraints into the sub-problem start-up combination scheme set, and store the corresponding output process.

[0254] S23, Interleaved Stepwise Optimization

[0255] S231. Connect the set of start-up combination schemes among the sub-problems according to the unit start-up and shutdown constraints, and retrieve the scheme with the maximum power generation in order.

[0256] S232. Shift the starting time period backward by one optimization step, return to step S22 to reallocate the subproblems and solve them;

[0257] S233, Iterate cyclically until the increase in power is less than the specified precision. .

[0258] S3. The dynamic programming algorithm is used to solve the load distribution model within the station.

[0259] Example 3

[0260] This embodiment takes five 1,000-megawatt-class hydropower stations on the upper reaches of the Yellow River—Longyangxia (1.28 million kW), Laxiwa (4.2 million kW), Lijiaxia (2 million kW), Gongboxia (1.5 million kW), and Jishixia (1.02 million kW)—as examples, and uses the method of Embodiment 2 to optimize the scheduling of the cascade hydropower stations.

[0261] According to the "Regulations on Water Dispatch of the Yellow River," the Longyangxia Reservoir must meet the daily water discharge target. Meanwhile, the five hydropower stations—Longyangxia, Laxiwa, Lijiaxia, Gongboxia, and Jishixia—also undertake peak shaving, frequency regulation, and phase regulation tasks for the Qinghai power grid during the non-flood season. In recent years, with the rapid growth of new energy installed capacity in Qinghai, the proportion of clean energy installed capacity has exceeded 90%, significantly increasing the difficulty of coordinating water and electricity dispatch at the upper reaches of the Yellow River. This has led to a series of problems, including daily unstable water levels at regulating power stations and long-term inefficient operation of generating units.

[0262] The multi-level, multi-objective optimization scheduling method of Example 2 was used to perform optimized scheduling calculations for the cascade hydropower stations in the upper reaches of the Yellow River, and the results were compared with actual scheduling results. The results show that this method can improve the power generation efficiency of the cascade hydropower stations, ensure power supply reliability, and optimize unit operating conditions, while avoiding frequent load adjustments at thermal power plants, all while meeting the requirements for downstream water discharge and high-proportion consumption of new energy sources. After optimization, the power generation of the cascade hydropower stations increased from 3.097 billion kWh to 3.183 billion kWh, an increase of 2.75%; the inefficient operating time of the units decreased from 4057.56 h to 2002.81 h, a decrease of 50.64%; and the average load distance of thermal power plants decreased from 9.1668 million kW to 1.0771 million kW, a decrease of 88.25%. See Table 1 for details.

[0263] Table 1. Optimized Scheduling Results of Cascade Hydropower Stations in the Upper Reaches of the Yellow River

[0264] Scheduling level Power Grid Layer Watershed layer Power station layer Optimization metrics Average distance of thermal power load Cascade hydropower station power generation Inefficient operation time of the unit Actual operation 9,166,800 kW 3.097 billion kWh 4057.56h Optimize operation 1,077,100 kW 3.183 billion kWh 2002.81h Optimization range 88.25% 2.75% 50.64%

[0265] In summary, the multi-level, multi-objective optimization scheduling method for cascade hydropower stations under complex water conservancy and power conditions proposed in this invention can effectively coordinate the multiple scheduling needs faced by cascade hydropower stations, such as grid security operation, clean energy consumption, and water resource security in the basin. It can also improve the power generation efficiency of cascade hydropower stations while ensuring power supply reliability, optimize unit operating conditions, and avoid large-scale adjustments to thermal power. It can provide a reference for the optimization scheduling decision of cascade hydropower under complex conditions.

[0266] Example 4

[0267] This embodiment provides a multi-level, multi-objective collaborative scheduling system for a cascade hydropower station group, used to implement the multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group in Embodiment 1 or Embodiment 2. The system includes:

[0268] The power grid hierarchical scheduling module is used to establish and solve a hydropower-thermal power coordinated optimization model with the objective of minimizing the average distance between thermal power loads, and obtain the total output process of cascade hydropower stations.

[0269] The cascade-level scheduling module is used to establish and solve an inter-station optimization model of cascade hydropower stations with the shape of the power output process of cascade hydropower stations as a constraint and the objective function of maximizing the power generation of cascade hydropower stations, so as to obtain the power output process of each hydropower station.

[0270] The power station hierarchical scheduling module is used to establish and solve a load distribution model within a hydropower station with the output of each hydropower station as a constraint and the objective function of minimizing the water consumption of the hydropower station units, so as to obtain the output process of each unit of each hydropower station.

[0271] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0272] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0273] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0274] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0275] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group, characterized in that, include: A hydropower-thermal power co-optimization model with the objective of minimizing the average distance between thermal power loads was established and solved to obtain the total power output process of the cascade hydropower stations. The objective function of the hydropower-thermal power co-optimization model with the objective of minimizing the average distance between thermal power loads is: ； in, The objective function of the hydropower-thermal power synergistic optimization model is... The time period number, =1,2,… , The total number of scheduling periods. express Thermal power load during certain periods; It must also meet the following constraints: power balance constraints, dispatchable power constraints of hydropower stations, output constraints, ramping capacity constraints, spinning reserve capacity constraints, and number of generating units in operation constraints of cascade hydropower stations. Using the shape of the power output process of cascade hydropower stations as a constraint, an inter-station optimization model for cascade hydropower stations is established and solved, with the objective function being the maximization of power generation of the cascade hydropower stations. The power output process of each hydropower station is obtained. The objective function of the inter-station optimization model for cascade hydropower stations with the objective function of maximizing power generation of the cascade hydropower stations is: ； in, The objective function is the optimization model between cascade hydropower stations. For the duration of the scheduling period, This refers to the serial number of the hydropower station. =1,2,…, , For the number of hydroelectric power stations, for Periodic hydroelectric power station contribution; It must also meet the following constraints: cascade hydropower station water level constraints, load shape constraints, water balance constraints, hydropower station output, power generation flow, discharge flow, reservoir water level upper and lower limits constraints, cascade hydropower station hydraulic connection constraints, water level fluctuation constraints, and hydropower station spinning reserve capacity constraints. Using the output of each hydropower station as a constraint, a load distribution model within the hydropower station is established and solved with the objective function of minimizing the water consumption for power generation by each hydropower station unit, yielding the output process of each unit in each hydropower station. The objective function of the load distribution model within the hydropower station with the objective function of minimizing the water consumption for power generation by each hydropower station unit is: ； in, Let be the objective function of the load allocation model within the hydropower station. For hydroelectric power station Unit serial number =1,2,…, , For hydroelectric power station Number of medium-sized generating units Indicates in Periodic hydroelectric power station medium-sized units The power generation flow rate; It must also meet the following constraints: power balance constraints, upper and lower limits of unit output and unit power generation flow, unit vibration zone constraints, minimum start-up and shutdown duration constraints, and number of units in operation constraints. During the solution process, the maximum power generation of the cascade hydropower stations obtained from the inter-station optimization model is used as the dispatchable power of the cascade hydropower stations at the grid level and fed back to the hydropower-thermal power co-optimization model. With this as a constraint, the hydropower-thermal power co-optimization model is optimized and solved, the total output process of the cascade hydropower stations is updated, and the load shape characteristics of the cascade hydropower stations are extracted and transferred to the inter-station optimization model. The optimization model of the cascade hydropower stations is optimized by taking the load shape characteristics of the cascade hydropower stations as constraints, optimizing the output of each hydropower station in the cascade, and feeding back the maximum power generation of the cascade hydropower stations to the hydropower-thermal power collaborative optimization model. This cycle repeats; During the solution process, the output of each cascade hydropower station obtained from the inter-station optimization model is fed back to the load distribution model within the hydropower station. Using this as a constraint, the load distribution model within the hydropower station is optimized to obtain the output of each unit. The power generation flow of each hydropower station is then fed back to the inter-station optimization model of the cascade hydropower station. The power generation flow of each hydropower station is the sum of the power generation flow of each unit in each hydropower station. The optimization model between cascade hydropower stations is optimized and solved with the power generation flow of each hydropower station as a constraint. The output of each cascade hydropower station is updated and fed back to the load distribution model within the hydropower station. This cycle continues.

2. The multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group according to claim 1, characterized in that, The objective function of the hydropower-thermal power co-optimization model must satisfy the following constraints: A1. Power balance constraints: ； in, for Grid load during the time period , , They represent The combined output of hydropower, wind power, and solar power during the specified time period; A2. Constraints on dispatchable power capacity of hydropower stations: ； in, This refers to the dispatchable power of cascade hydropower stations; A3. Output Constraints: ； ； in, , These are the lower and upper limits of thermal power output, respectively. , These are the lower and upper limits of hydropower output, respectively. A4. Climbing ability constraint: ； in, This represents the maximum climbing capacity of thermal power plants. A5. Spinning reserve capacity constraint: ； in, For hydroelectric rotating reserve capacity, For rotating reserve capacity of thermal power plants; A6. Constraints on the number of generating units in operation at cascade hydropower stations: ； in, for Number of generating units in cascade hydropower stations during a given time period. The maximum and minimum number of generating units that can be operated at a cascade hydropower station.

3. The multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group according to claim 1, characterized in that, The objective function of the optimization model for the inter-stations of the cascade hydropower stations must satisfy the following constraints: B1. Water level constraints of cascade hydropower stations: ； in, This refers to the planned water outflow from the reservoir of the leading hydropower station. for Periodic hydroelectric power station The average outflow from the reservoir, and They are respectively =1 and =T-time hydropower station The reservoir water level and They represent hydroelectric power stations. Initial and final water level control requirements during the scheduling period; B2. Load shape constraint: ； in, The load shape characteristics of the cascade hydropower stations are determined based on the solution results of the hydropower-thermal power synergistic optimization model; B3. Water balance constraint: ； in, for Periodic hydroelectric power station Reservoir capacity, for Periodic hydroelectric power station Average inbound flow for Periodic hydroelectric power station The outflow rate, for Periodic hydroelectric power station Water loss due to evaporation and seepage from the reservoir; B4. Hydropower station output, power generation flow, discharge flow, and upper and lower limits of reservoir water level: ； in, , Hydropower stations Upper and lower limits of output for Periodic hydroelectric power station Power generation flow, , Hydropower stations Upper and lower limits of power generation flow rate , Hydropower stations The upper and lower limits of the discharge flow. for Periodic hydroelectric power station The reservoir water level , Hydropower stations Upper and lower limits of reservoir water level; B5. Hydraulic connection of cascade hydropower stations: ； in, for Periodic hydroelectric power station Average outbound flow For hydroelectric power station Outflow reaches hydropower station The time required for Periodic hydroelectric power station To the hydroelectric power station Interval flow between; B6. Water level fluctuation constraints: ； in, Hydropower stations in adjacent time periods Maximum permissible fluctuation in water level; B7. Spinning reserve capacity constraints of hydropower stations: ； in, For hydroelectric power station Rotating reserve capacity, For hydroelectric power station The rotating reserve capacity factor.

4. The multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group according to claim 1, characterized in that, The objective function of the load distribution model within the hydropower station must satisfy the following constraints: C1. Power balance constraints: ； in, Indicates in Periodic hydroelectric power station medium-sized units contribution; C2. Unit output and upper / lower limits for unit power generation flow: ； in, , Hydropower stations medium-sized units Upper and lower limits of output , Hydropower stations medium-sized units Upper and lower limits for power generation flow; C3. Unit vibration zone constraints: ； in, and They are respectively Periodic hydroelectric power station medium-sized units Minimum and maximum output, , Hydropower stations medium-sized units The The upper and lower limits of the output power in each vibration zone; C4. Minimum start-up and shutdown duration constraint for the unit: ； in, for Periodic hydroelectric power station medium-sized units The running status, This indicates that the unit is powered on; otherwise... ; , For hydroelectric power station medium-sized units Minimum downtime and minimum startup time; For unit start-up operation variables, express Periodic hydroelectric power station medium-sized units The power-on operation was performed; otherwise... ; This is a variable for unit shutdown operations. express Periodic hydroelectric power station medium-sized units The shutdown operation was performed; otherwise... ; C5. Constraint on the number of generating units in operation: ； in, for Periodic hydroelectric power station Number of medium-sized generating units in operation. For hydroelectric power station Maximum and minimum number of machines that can be started.

5. A multi-level, multi-objective coordinated scheduling method for a cascade hydropower station group according to claim 2, characterized in that, Solving the hydropower-thermal power synergistic optimization model includes: S11, Based on the load forecast for the next day New energy power forecast Determine the equivalent load for the next day , ; S12. The total power generation of the cascade hydropower stations in the previous dispatch cycle. As the initial power source, the load command for the cascade hydropower stations is obtained using a successive load shedding method. ; S13, Load assessment command for cascade hydropower stations Does it meet the output constraint? If not, consider the thermal power plant's ramp-up capability. The output process of the cascade hydropower stations during this period and the nearby periods is adjusted, and the adjustment amount is spread out from the other periods until the load command of the cascade hydropower stations fully meets the output constraints. S14. Extracting the load shape characteristics of cascade hydropower stations based on the following formula. This feedback is fed back to the optimization model between the cascade hydropower stations to optimize the dispatchable power capacity of the cascade hydropower stations. , ； S15. Determine the increase in dispatchable power capacity of cascade hydropower stations. Does it meet the preset accuracy? If satisfied, the iteration ends, and the output processes of thermal power, hydropower stations at each stage, and generating units within each hydropower station are output. If not satisfied, the dispatchable power of the hydropower stations at each stage is updated, and the process returns to step S12. The iteration continues until the increase in the dispatchable power of the hydropower stations at each stage meets the preset accuracy.

6. The multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group according to claim 3, characterized in that, Solving the optimization model between cascade hydropower stations includes: S211, Based on the comprehensive output coefficient of each hydropower station Helong Hydropower Station Outflow Plan Estimate the total power generation of each hydropower station during the dispatch period ; S212, Based on the total power generation of each hydropower station during the dispatch period and the load shape characteristics of hydropower stations The power output process lines of each hydropower station were generated using a synchronous peak-shaving strategy, as follows: ； S213. Determine the start-up plan for each hydropower station unit based on the principle of minimum number of units required to be started. And correct it according to the unit start-up and shutdown constraints; S214. Taking the output of each hydropower station as a constraint, and combining the start-up plans of each hydropower station unit. Based on the load distribution model within the hydropower station, the power generation flow of each generating unit is calculated, thereby obtaining the power generation flow of the hydropower station. Water level process and the process of discharge flow ; S215. Determine whether the total water volume / final water level of the hydropower station meets the water level constraints of the cascade hydropower stations. If not, determine the water volume / water level deviation according to a certain step size. Adjust the total power output of the hydropower station during the scheduling period, return to S212, recalculate, until all the cascade hydropower stations have been calculated, and obtain the initial solution of the power output of each cascade hydropower station. S221. Decompose the scheduling cycle with the unit start-up and shutdown time as the optimization step size, and combine every two optimization time periods after the start time into a new sub-problem. S222, Discretize the reservoir capacity status of each hydropower station between optimization steps into... The data are combined to form a set of reservoir capacity statuses for cascade hydropower stations. Calculate and optimize step size and water volume limit ,in, For hydroelectric power station Storage capacity status ; S223. Determine the feasible number of generating units to be started at each hydropower station in the cascade under different water volume constraints. The cascade hydropower station commissioning scheme , For hydroelectric power station Storage capacity status The number of machines started; S224. The sum of the initial output solutions of each hydropower station within the optimization period is distributed among the hydropower stations according to their operating capacity. The power generation flow is determined using a load distribution model within the hydropower station. And calculate whether the water volume limit is met. If the water volume limit is not met, the output process will be adjusted according to the load shape until the water volume limit calculation accuracy is met. S225. Combine the start-up schemes in the two optimization time period start-up scheme sets one by one, store the schemes that meet the unit start-up and shutdown constraints into the sub-problem start-up combination scheme set, and store the corresponding output process. S231. Connect the sub-problems according to the unit start-up and shutdown constraints to form the set of start-up combination schemes, and search for the scheme with the maximum power generation in order. S232. Shift the starting time period backward by one optimization step, return to step S221 to reallocate the subproblems and solve them; S233, iterate in a loop until the increase in power is less than the preset precision.

7. A multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group according to claim 4, characterized in that, Solving the load distribution model within the hydropower station includes: The dynamic programming algorithm is used to solve the load distribution model within the hydropower station.

8. A multi-level, multi-objective collaborative scheduling system for a cascade hydropower station group, characterized in that, The system is used to implement the multi-level, multi-objective collaborative scheduling method for a cascade hydropower station group as described in any one of claims 1 to 7, the system comprising: The power grid hierarchical scheduling module is used to establish and solve a hydropower-thermal power coordinated optimization model with the objective of minimizing the average distance between thermal power loads, and obtain the total output process of cascade hydropower stations. The cascade-level scheduling module is used to establish and solve an inter-station optimization model of cascade hydropower stations with the shape of the power output process of cascade hydropower stations as a constraint and the objective function of maximizing the power generation of cascade hydropower stations, so as to obtain the power output process of each hydropower station. The power station hierarchical scheduling module is used to establish and solve a load distribution model within a hydropower station with the output of each hydropower station as a constraint and the objective function of minimizing the water consumption of the hydropower station units, so as to obtain the output process of each unit of each hydropower station.

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