Short-term scheduling method for cascade hybrid pumped storage power station based on additional pump station

Abstract

The invention discloses a short-term scheduling method for a cascade hybrid pumped storage power station based on pump station addition, which comprises the following steps of: adding an energy storage pump station between cascade series hydropower stations, and dynamically drawing up a reservoir capacity constraint by adopting a reservoir capacity dynamic control strategy considering the cascade hybrid pumped storage power station; constructing a cascade hybrid pumped storage power station short-term scheduling model based on the added energy storage pump station, wherein the cascade hybrid pumped storage power station short-term scheduling model takes the minimum mean square error of the residual load of a power grid as a target; solving the scheduling model based on an improved step-by-step optimization algorithm POA; and a comprehensive risk-benefit evaluation system is constructed, multi-dimensional targets of a system scheduling level and a power station operation level are considered, and the influence of additionally arranging an energy storage pump station on the risk and benefit of the power grid is deeply analyzed. The method can be used for guiding daily scheduling of the cascade hybrid pumped storage power station based on the additionally-arranged pump station, wind and light abandoning phenomena are reduced to the maximum extent while safe and stable operation of a power system is guaranteed, and the absorption capacity of wind and light resources and the power supply reliability of the power system are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of multiple energy sources, and relates to a short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations. Background Art

[0002] At present, the contradiction between new energy consumption and the safe operation of the power system urgently requires the construction of a large-scale regulating power source system with fast and efficient regulation capabilities. Pumped-storage power stations are currently the most mature in technology, the most economical, and the most suitable for large-scale development. They have the advantages of large energy storage capacity, flexible operation, clean and efficient, etc., and can play functions such as energy storage, peak shaving and valley filling, and emergency standby in the power system. The hybrid pumped-storage power station transformed by adding reversible units or energy storage pumping stations and building new upper reservoirs on the basis of conventional hydropower stations has the advantages of low construction cost, short development cycle, and small impact on reservoir inundation compared with pure pumped-storage power stations. Therefore, existing research has proposed to build a hybrid pumped-storage power station by adding energy storage pumping stations to conventional hydropower stations, realizing a clean energy development and utilization model of multi-energy complementary scheduling operation of water, wind and light storage, which is an important means to promote the development of future clean energy.

[0003] However, most of the current scheduling research on hybrid pumped-storage power stations is for single-stage hybrid pumped-storage power stations. When conditions are suitable, traditional cascaded hydropower stations have the potential to be developed into cascaded hybrid pumped-storage power stations, and the scheduling of cascaded hybrid pumped-storage power stations is more difficult. On the one hand, the pumping condition of the hybrid pumped-storage power station expands the one-way hydraulic connection of the original cascaded reservoir into a two-way hydraulic cycle, and the pumping flow is newly added to the inflow and outflow items in the water balance equation, making it more difficult to control the reservoir capacity; on the other hand, the scheduling objects in the hybrid pumped-storage power station include cascaded hydropower stations and energy storage pumping stations, which changes the single decision variable into a multi-variable decision variable in the short-term model solving process, greatly increasing the solving difficulty. Therefore, problems such as how to analyze the water balance relationship of cascaded hybrid pumped-storage power stations, how to control the reservoir capacity, and how to solve the short-term model considering the complex coupling relationship between the operating power, pumping flow and working head of hybrid pumped-storage power stations remain to be answered. Summary of the Invention

[0004] Object of the Invention: The object of the invention is to provide a short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations, to guide the daily scheduling of a cascaded hybrid pumped-storage power station based on adding pumping stations, and while ensuring the safe and stable operation of the power system, minimize the phenomenon of wind and light abandonment to the greatest extent, and improve the consumption capacity of wind and light resources and the power supply reliability of the power system.

[0005] Technical Solution: The short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations described in the invention includes the following steps:

[0006] An energy storage pumping station is added between cascade hydropower stations, and a dynamic control strategy for the reservoir storage capacity of a cascade hybrid pumped-storage power station is adopted to dynamically determine the storage capacity constraint.

[0007] A short-term scheduling model of a cascade hybrid pumped-storage power station based on the added energy storage pumping station is constructed with the goal of minimizing the mean square deviation of the remaining load of the power grid.

[0008] Based on the improved Progressive Optimization Algorithm (POA), a decoupling and coordination mechanism is constructed for the coupling relationship among the pumping flow rate, operating power, and upstream and downstream reservoir water levels of the cascade energy storage pumping station to solve the scheduling model. In the improved POA, in the initial solution generation stage, based on the objective function of minimizing the mean square deviation of the remaining load, the hydropower station tracks the remaining load of the power grid and discharges water during the pump station shutdown period. In the feasible region generation stage, a dynamic feasible region generation strategy combining forward and backward deductions is adopted. During the pump station shutdown period, according to the water balance constraint, and during the pump station operation period, according to the dynamic control strategy of the storage capacity, a dynamic feasible region within the scheduling period is formed. For the working conditions involving multiple decision variables, two-stage trial calculations are carried out, that is, the pumping flow rate, working head, and operating power of the upper and lower energy storage pump stations of the current hydropower station are fixed respectively.

[0009] A comprehensive risk-benefit evaluation system is constructed, taking into account the multi-dimensional objectives at the system scheduling level and the power station operation level, and deeply analyzing the impact of adding an energy storage pumping station on the power grid risk and benefit.

[0010] Furthermore, after adding an energy storage pumping station between cascade hydropower stations, the dynamic control strategy of the reservoir storage capacity follows the following water balance relationship:

[0011]

[0012] where, V s,t-1 ′ and V s,t ′ are the initial and final storage capacities of hydropower station s at the beginning and end of the t-th period after adding the energy storage pumping station, respectively; and are the inflow and outflow water volumes of hydropower station s in the t-th period after adding the energy storage pumping station, respectively; I s,t , are the natural inflow rate, power generation flow rate, and water discharge flow rate of hydropower station s in the t-th period, respectively; is the outflow rate of hydropower station s-1 in the (t-τ)-th period; τ is the water lag time between the s-th and (s + 1)-th reservoirs; △t is the period length; is the pumping flow rate of pump station s from reservoir s + 1 to reservoir s in the t-th period; is the pumping flow rate of pump station s from reservoir s to reservoir s-1 in the t-th period; α s , α s-1 are both binary variables. When an energy storage pumping station is added between hydropower station s and hydropower station s + 1, αs = 1, otherwise α s = 0; When an energy storage pumping station is added between hydropower station s-1 and hydropower station s, α s-1 = 1, otherwise α s-1 = 0.

[0013] Furthermore, during the pumping operation of the energy storage pumping station, the reservoir capacity constraint is dynamically formulated, and the reservoir capacity constraint is:

[0014]

[0015] where V s,t is the end reservoir capacity of reservoir s at time period t; are the reservoir capacities corresponding to the dead water level and the normal storage level of reservoir s respectively; are the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pumping station s respectively; are the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pumping station s-1 respectively; T p is the continuous pumping duration starting from time period t.

[0016] Furthermore, the objective function of the short-term scheduling model of the cascade hybrid pumped-storage power station with an added energy storage pumping station is:

[0017]

[0018] where σ is the standard deviation of the remaining load; t is the time period, t = 1, 2, 3,..., T, and T is the number of time periods within the scheduling period; P t represents the remaining load of the system at time period t; represents the average value of the remaining load; P t G and P t W and P t S and P t H are the load command, total wind power output, total photovoltaic power output, and total hydropower output of the power grid at time period t respectively; P t P is the sum of the operating powers of the energy storage pumping station at time period t.

[0019] Furthermore, after adding an energy storage pumping station between cascade hydropower stations, on the basis of satisfying the conventional constraint conditions, the scheduling model also introduces a number of new physical and operating constraints, including pumping station energy consumption constraint, pumping flow rate constraint, and pumping station working power constraint; specifically as follows:

[0020] Pumping station power consumption constraint:

[0021]

[0022] Among them, is the operating power of pumping station s at time period t; is the working head of pumping station s at time period t; ρ is the density of the pumped liquid; g is the acceleration due to gravity; η s is the overall efficiency of pumping station s; is the motor efficiency of pumping station s; is the pump efficiency of pumping station s; is the pressure pipeline efficiency of pumping station s;

[0023] Pumping flow rate constraint:

[0024]

[0025]

[0026] Among them, is the pumping flow rate of pumping station s at time period t; is the minimum allowable pumping flow rate of pumping station s; is the maximum allowable pumping flow rate of pumping station s at time period t; are respectively the maximum pumping flow rates of the lower reservoir of pumping station s "with water available for pumping" and the upper reservoir of pumping station s "with storage available in the reservoir"; is the inflow of hydropower station s + 1 at time period t; is the minimum discharge of hydropower station s + 1; is the minimum allowable reservoir capacity of the lower reservoir of pumping station s + 1 under the reservoir capacity control strategy in time period t; V s+1,t is the reservoir capacity of the lower reservoir of pumping station s + 1 in time period t; is the inflow of hydropower station s at time period t; is the minimum discharge of hydropower station s; is the maximum allowable reservoir capacity of the upper reservoir of pumping station s under the reservoir capacity control strategy in time period t; V s,t is the reservoir capacity of the lower reservoir of pumping station s in time period t;

[0027] Pumping station working power constraint:

[0028]

[0029] Among them, is the working power of pumping station s in time period t; is the minimum allowable working power of pumping station s; is the maximum allowable working power of pumping station s; is a binary variable representing the operating state of pumping station s in time period t.

[0030] Furthermore, the initial solution of the cascade hydropower stations in the improved progressive optimization algorithm is:

[0031]

[0032] Among them, is the discharge flow of the s-th power station at the t-th time period calculated from the initial solution; is the total discharge flow corresponding to the total available water volume obtained by the s-th power station during the calculation period; P s,t is the remaining load faced by the s-th power station at the t-th time period; P min is the minimum value of the remaining load after the regulation of the hydropower station; is the minimum discharge flow of the hydropower station s.

[0033] Furthermore, the cascade hydropower stations calculate the initial and final reservoir capacities according to the water level-reservoir capacity relationship. When the pump station stops operating, according to the water balance equation and the discharge flow constraint, and when the pump station is working, according to the dynamic control strategy of the reservoir capacity, the forward feasible interval of the reservoir capacity and the reverse feasible interval of the reservoir capacity are deduced within the scheduling period, and the intersection of the above intervals is obtained to get the feasible region of the reservoir capacity [V s,1 , V s,1 and [V s,T+1 , V s,T+1 ; among them, V s,1 is the initial reservoir capacity of the s-th reservoir at the first time period, are respectively the lower and upper limits of the feasible region of the initial reservoir capacity of the s-th reservoir at the second time period, are respectively the lower and upper limits of the feasible region of the initial reservoir capacity of the s-th reservoir at the t-th time period, are respectively the lower and upper limits of the feasible region of the initial reservoir capacity of the s-th reservoir at the T-th time period, V s,T+1 is the final reservoir capacity of the s-th reservoir at the T-th time period.

[0034] Furthermore, in the improved progressive optimization algorithm, it is necessary to conduct a trial calculation on the operation process of the pump station. If the hydropower station s is only the upper reservoir or the lower reservoir of the energy storage pump station, the first-stage trial calculation is carried out, fixing the pumping flow rate, working head, and operating power of the energy storage pump station s, and conducting a trial calculation on the energy storage pump station s-1; the steps of the trial calculation are: ① Assume the pumping flow rate of the pump station or ② Calculate the working head of the pump station or ③ Calculate the operating power of the pump station or ④ Use the bisection method to update the pumping flow rate to or or and return to ② when; ⑤ or stop the iteration when;

[0035] If the hydropower station s is both the upper reservoir of the energy storage pumping station s and the lower reservoir of the energy storage pumping station s-1, then it proceeds to two-stage trial calculations. In the first stage, the pumping flow rate, working head, and operating power of the energy storage pumping station s are fixed, and trial calculations are carried out for the energy storage pumping station s-1. In the second stage, the trial calculation results of the energy storage pumping station s-1 are fixed, and trial calculations are carried out for the energy storage pumping station s.

[0036] Furthermore, the constructed comprehensive risk-benefit evaluation system includes: selecting power generation and power generation benefits, the peak-valley difference of the remaining load of the power grid, the average value of the remaining load of the power grid, the mean square deviation of the remaining load of the power grid, and the consumption of abandoned electricity by the pumping station as comprehensive benefit evaluation indicators, and selecting the amount of abandoned electricity, the rate of abandoned electricity, the reservoir water level fluctuation coefficient, and the difference coefficient of the reservoir discharge flow rate as comprehensive risk evaluation indicators.

[0037] On the other hand, a short-term scheduling system for a cascade hybrid pumped-storage power station based on adding pumping stations includes:

[0038] A dynamic control strategy unit, which is used to add energy storage pumping stations between cascade series hydropower stations and adopt a dynamic control strategy for the reservoir storage capacity considering the cascade hybrid pumped-storage power station to dynamically formulate the storage capacity constraint;

[0039] A scheduling model construction unit, which is used to construct a short-term scheduling model for a cascade hybrid pumped-storage power station based on adding energy storage pumping stations with the goal of minimizing the mean square deviation of the remaining load of the power grid;

[0040] A scheduling model solving unit, which is used to construct a decoupling and coordination mechanism based on the improved Progressive Optimization Algorithm (POA) for the coupling relationship between the pumping flow rate, operating power of the cascade energy storage pumping stations, and the water levels of the upstream and downstream reservoirs, and solve the scheduling model. For the improved Progressive Optimization Algorithm (POA), in the initial solution generation stage, based on the objective function of minimizing the mean square deviation of the remaining load, the hydropower station tracks the remaining load of the power grid and discharges water during the shutdown period of the pumping station. In the feasible region generation stage, a dynamic feasible region generation strategy combining forward and backward inferences is adopted. During the shutdown period of the pumping station, according to the water balance constraint, and during the working period of the pumping station, according to the dynamic control strategy of the storage capacity, a dynamic feasible region within the scheduling period is formed. For the working conditions involving multiple decision variables, two-stage trial calculations are carried out, that is, the pumping flow rate, working head, and operating power of the upper and lower energy storage pumping stations of the current hydropower station are fixed respectively;

[0041] An evaluation unit, which is used to construct a comprehensive risk-benefit evaluation system, taking into account the multi-dimensional objectives at the system scheduling level and the power station operation level, and deeply analyzing the impact of adding energy storage pumping stations on the risks and benefits of the power grid.

[0042] Beneficial effects: Compared with the prior art, the remarkable technical effects of the present invention are as follows: (1) Improve the new energy consumption level of the system and alleviate the problem of wind and photovoltaic curtailment. On the one hand, the short-term scheduling of the cascade hybrid pumped-storage power station can make full use of the flexible regulation ability of the hydropower station to compensate for the random fluctuation characteristics of wind and light output, improve the stability of the system output, and promote the high proportion consumption of wind power and photovoltaic power. On the other hand, using the surplus power of the system as the power source of the pumping station and converting potential curtailment into potential energy storage can significantly reduce the curtailment of the system. (2) Improve the safety of the dispatching operation of the hydropower station. The proposed dynamic control strategy for the reservoir storage capacity of the cascade hybrid pumped-storage power station effectively releases the pumping regulation potential of the energy storage pumping station by ensuring that there is water to pump in the lower reservoir and there is a reservoir to store in the upper reservoir. This strategy not only reduces the regulation load generated by the hydropower units due to frequent response to wind and light fluctuations, reduces equipment loss and operation risks, but also enables the system to have the ability to "actively adjust the water level", enhances the adaptability to incoming water changes and load fluctuations, and thus significantly improves the overall operation safety and dispatching reliability of the hydropower station. (3) By constructing a collaborative optimization dispatching mechanism for the cascade hydropower station and the energy storage pumping station, giving full play to the fast response characteristics of hydropower and the energy bidirectional regulation ability of the energy storage pumping station, significantly enhancing the peak shaving and frequency modulation ability of the system, effectively reducing load fluctuations, and improving the stability of the system output. At the same time, by storing the surplus power of the system in the energy storage pumping station, not only the level of wind and photovoltaic curtailment is reduced, the resource utilization efficiency is improved, but also a practical path for realizing multi-energy complementarity and coordinated operation of the power grid, load and energy storage is provided. This technical solution has good scalability and implementation value, provides strong support for the construction of a new power system, and helps to promote the safe and efficient operation of a power system mainly based on new energy. Brief Description of the Drawings

[0043] Figure 1 It is the flowchart of the method of the present invention;

[0044] Figure 2 It is the schematic diagram of the transformation of the traditional cascade hydropower energy storage;

[0045] Figure 3 It is the flowchart for solving the short-term scheduling model. Detailed Embodiments

[0046] The present invention will be described in detail below with reference to the drawings and specific embodiments: To make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0047] As Figure 1 shown, the short-term scheduling method of the cascade hybrid pumped-storage power station based on adding a pumping station according to the present invention includes the following steps:

[0048] S1. Propose a dynamic control strategy for the reservoir storage capacity of the cascade hybrid pumped-storage power station;

[0049] The water balance equation is the core principle of reservoir operation, which describes the mutual relationship among the inflow water volume, outflow water volume, and storage water volume of the reservoir. The traditional water balance equation is Equation (1), where the inflow water volume includes natural inflow and the outflow water volume of the upper reservoir, and the outflow water volume includes the power generation water volume and the water abandonment volume of the hydropower station. After adding energy storage pump stations between cascade hydropower stations, the topological structure of the basin water network changes significantly (as shown in Figure 2 ), and the newly added energy storage pump station scheduling unit changes the unidirectional flow path of the hydraulic connection from upstream to downstream into a bidirectional circulation loop between upstream and downstream. Taking the hydropower station in Figure 2 as an example, after the energy storage transformation, the inflow water volume in the water balance equation adds the pumping water volume of the energy storage pump station, and the outflow water volume adds the pumping water volume of the energy storage pump station. Therefore, the water balance relationship changes from Equation (1) to Equation (2).

[0050]

[0051] Among them, V s,t-1 , V s,t are the initial and final reservoir storage capacities of hydropower station s at the t-th time period respectively; and are the inflow water volume and outflow water volume of hydropower station s at the t-th time period respectively; V s,t-1 ′, V s,t ′ are the initial and final reservoir storage capacities of hydropower station s at the t-th time period after adding the energy storage pump station respectively; and are the inflow water volume and outflow water volume of hydropower station s at the t-th time period after adding the energy storage pump station respectively; I s,t , are the natural inflow discharge, power generation discharge, and water abandonment discharge of hydropower station s at the t-th time period respectively; is the outflow discharge of hydropower station s-1 at the (t-τ)-th time period; τ is the water flow lag time between the s-th and (s + 1)-th reservoirs; △t is the time period length; is the pumping water flow of pump station s from reservoir s + 1 to reservoir s at the t-th time period; is the pumping water flow of pump station s from reservoir s to reservoir s-1 at the t-th time period; α s , α s-1 are both binary variables. When an energy storage pump station is added between hydropower station s and hydropower station s + 1, α s = 1, otherwise α s = 0; when an energy storage pump station is added between hydropower station s-1 and hydropower station s, α s-1 = 1, otherwise α s-1 = 0.

[0052] During the pumping operation of the energy storage pumping station, to ensure its normal operation and maximize the pumping capacity, it is necessary to reasonably utilize the water volume and storage capacity space of the upper and lower reservoirs. Specifically, the lower reservoir needs to reserve sufficient water volume in advance according to the pumping flow rate and pumping duration of the energy storage pumping station, that is, to ensure "there is water to pump", to avoid shutdown due to insufficient water volume during pumping; at the same time, the upper reservoir needs to reserve sufficient storage capacity space to ensure "there is a reservoir to store", and prevent the reservoir from discharging water due to exceeding the storage capacity limit. Therefore, in order to give full play to the pumping efficiency of the energy storage pumping station, the present invention proposes a dynamic control strategy for the reservoir storage capacity of a cascade hybrid pumped-storage power station. This strategy dynamically formulates the storage capacity constraint according to the inflow and outflow of the hydropower station s in the current period, the pumping flow rate and pumping duration of pumping stations s and s-1, as follows:

[0053]

[0054] Among them, are respectively the storage capacity corresponding to the dead water level of reservoir s and the storage capacity corresponding to the normal storage level; are respectively the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pumping station s; are respectively the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pumping station s-1; T p is the continuous pumping duration after period t.

[0055] S2. Establish a short-term scheduling model for a cascade hybrid pumped-storage power station with an additional pumping station;

[0056] Considering that the energy storage pumping station can act as a "valley filling" for the load during the low load period, and the conventional hydropower unit can act as a "peak shaving" for the power source during the high load period, in order to ensure the safe and stable operation of the power system and minimize the curtailment of wind and solar power as much as possible, a short-term peak shaving scheduling model for a cascade hybrid pumped-storage power station with an additional pumping station is constructed.

[0057] (1) Objective function:

[0058] To alleviate the problem of "excess during the day and shortage at night" in the power grid power supply, meet the power supply and demand balance of the power grid and maintain the safe and stable operation of the power system, the model aims to minimize the mean square deviation of the remaining load in the power grid, so that the remaining load after being regulated by the cascade hybrid pumped-storage power station is as stable as possible. The objective function is as follows:

[0059]

[0060] Among them, σ is the mean square deviation of the remaining load; t is the period, t = 1, 2, 3,..., T; P t represents the remaining load of the system in period t; represents the average value of the remaining load, P tG , P t W , P t S , P t H are the load command, total wind power output, total photovoltaic power output, and total hydropower station output of the power grid during the t period; P t P is the sum of the operating powers of the energy storage pumping stations during the t period.

[0061] (2) Constraint conditions:

[0062] ① Storage capacity constraint:

[0063]

[0064] ② Output constraint:

[0065]

[0066] Among them, N s,t , are the output, minimum output, and maximum output of hydropower station s during the t-th period, respectively.

[0067] ③ Generation flow constraint:

[0068]

[0069] Among them, is the generation flow of hydropower station s during the t-th period; are the minimum generation flow and maximum generation flow of hydropower station s, respectively.

[0070] ④ Discharge flow constraint:

[0071]

[0072] Among them, is the discharge flow of hydropower station s during the t-th period; are the minimum discharge flow and maximum discharge flow of hydropower station s, respectively.

[0073] ⑤ Hydraulic connection constraint:

[0074]

[0075] ⑥ Water volume balance constraint:

[0076]

[0077] ⑦ Comprehensive utilization requirements:

[0078]

[0079] Among them, d is the scheduling period; W s,d is the comprehensive water utilization demand of hydropower station s during the scheduling period.

[0080] ⑧ Pumping station power consumption constraint:

[0081]

[0082] Among them, is the operating power of pumping station s at the t-th time period; is the working head of pumping station s at the t-th time period; ρ is the density of the pumped liquid, which is the density of water here; g is the acceleration due to gravity; η s is the overall efficiency of pumping station s; is the motor efficiency of pumping station s; is the pump efficiency of pumping station s; is the pressure pipeline efficiency of pumping station s.

[0083] ⑨ Pumping flow constraint:

[0084] When pumping station s is working, in addition to meeting the maximum and minimum pumping flow constraints, its pumping flow also needs to meet the constraints that the water volume in the lower reservoir can be pumped and the water volume can be stored in the upper reservoir. Specifically, the formula is as follows:

[0085]

[0086] Among them, is the pumping flow of pumping station s at the t-th time period; is the minimum allowable pumping flow of pumping station s; is the maximum allowable pumping flow of pumping station s at the t-th time period; are respectively the maximum pumping flow of "water available for pumping" in the lower reservoir of pumping station s and the maximum pumping flow of "reservoir available for storage" in the upper reservoir; is the inflow of hydropower station s+1 at the t-th time period; is the minimum discharge of hydropower station s+1; is the minimum allowable reservoir capacity of the lower reservoir of pumping station s+1 under the reservoir capacity control strategy in the t-th time period; V s+1,t is the reservoir capacity of the lower reservoir of pumping station s+1 in the t-th time period; is the inflow of hydropower station s at the t-th time period; is the minimum discharge of hydropower station s; is the maximum allowable reservoir capacity of the upper reservoir of pumping station s under the reservoir capacity control strategy in the t-th time period; V s,t is the reservoir capacity of the lower reservoir of pumping station s in the t-th time period.

[0087] ⑩ Pumping station working power constraint:

[0088]

[0089] Among them, is the working power of pumping station s at time period t; is the minimum allowable working power of pumping station s; is the maximum allowable working power of pumping station s; is a binary variable representing the operating state of pumping station s at time period t ( in the on state; in the off state).

[0090] S3. An improved Progressive Optimization Algorithm (POA) is proposed to solve the short-term scheduling model of a cascade hybrid pumped-storage power station with additional pumping stations;

[0091] The Progressive Optimization Algorithm (POA) was proposed by Canadian scholars H.R. Howson and N.G Sancho in 1975. This algorithm combines the optimization principle in the dynamic programming algorithm and aims to solve complex optimization problems. After adding energy storage pumping stations to a cascade hydropower station to form a hybrid pumped-storage power station, there are complex hydraulic connections. How to schedule the cascade hybrid pumped-storage power station is a high-dimensional, multi-constrained, non-linear optimization problem. When solving the model, two new unknowns are added to the water balance equation, and the operation processes of the hydropower station and the energy storage pumping station affect each other, increasing the difficulty of solution. The decision-making objects include not only the reservoir storage capacity but also the operating power, pumping flow rate, pumping duration, etc. of the pumping station. Among them, how to handle the coupling relationship between the pumping flow rate, operating power of the cascade energy storage pumping station, and the water levels of the upstream and downstream reservoirs is the key difficulty to be solved. For this reason, the present invention proposes an improved POA algorithm to solve the short-term scheduling model of a cascade hybrid pumped-storage power station with additional pumping stations. The improvement points of the POA algorithm include: (1) Initial solution improvement; in the initial solution generation stage (step 3 below), based on the objective function of minimizing the mean square error of the remaining load, the hydropower station tracks the remaining load of the power grid and discharges water during the shutdown period of the pumping station. Compared with the traditional equal-flow method and equal-output method for generating the initial solution, this initial solution generation strategy can improve the peak shaving effect of the scheduling results of the cascade hydropower station. (2) Feasible region improvement; adopt a dynamic feasible region generation strategy for reservoir storage capacity that combines forward and reverse deductions (step 4 below). According to the water balance constraint during the shutdown period of the pumping station and the dynamic control strategy of the reservoir storage capacity during the working period of the pumping station, a dynamic feasible region within the scheduling period is formed. Compared with the limitation of the fixed feasible region of the traditional POA algorithm, this strategy can avoid searching for infeasible regions and improve the model solution efficiency. (3) Multivariate decision variable processing strategy; for the working conditions involving multivariate decision variables (step 8 below), a two-stage trial calculation is adopted, that is, the pumping flow rate, working head, and operating power of the upper and lower energy storage pumping stations of the current hydropower station are fixed respectively. This strategy simplifies the processing of multivariate decision variables through variable decoupling and hierarchical solution.

[0092] The model solution process is as Figure 3 shown, and the specific solution steps are as follows:

[0093] Step 1: Set the number of power stations S, the number of scheduling periods T, the maximum number of iterations k max , the iteration termination accuracy ε, and initialize the iteration number k = 1, the power station s = 1, the period t = 1, and ε is a sufficiently small positive number.

[0094] Step 2: Generate the initial solution of the pumping station operating state. According to the given grid load curve and new energy output curve, the net load curve is deduced. During the periods when new energy is continuously curtailed, the pumping station is in the operating state, and the pumping flow rate is assumed to be the pumping flow rate under the rated working condition of the energy storage pumping station.

[0095] Step 3: Generate the initial solution of the cascade hydropower operation process. During the periods when the pumping station is shut down, to track the grid load and utilize the peak shaving capacity of the hydropower station, the discharge flow rate is calculated according to Equation (19); during the periods when the pumping station is operating, since the new energy output is large, to promote the consumption of new energy, the hydropower station discharges at the minimum flow rate that meets the comprehensive utilization requirements. After obtaining the discharge flow rate of each period of the current hydropower station, the reservoir water level of each period is calculated through the water balance equation, and then the output process is calculated. If there is a downstream hydropower station, the above hydropower initial solution generation strategy is looped; if there is no downstream power station, the initial solutions of each power station in the cascade are output.

[0096]

[0097] Among them, is the discharge flow rate of the s-th power station at the t-th period calculated from the initial solution; is the total discharge flow rate corresponding to the total available water volume obtained by the s-th power station during the calculation period; P s,t is the remaining load faced by the s-th power station at the t-th period; P min is the minimum value of the remaining load after being regulated by the hydropower station; is the minimum discharge flow rate of the hydropower station s.

[0098] Step 4: Generate the dynamic feasible region for each power station from upstream to downstream. Given the initial and final water levels that meet the comprehensive utilization requirements during the entire scheduling period, the initial and final reservoir capacities are obtained according to the water level-reservoir capacity relationship. When the pumping station is shut down, according to the water balance equation and the discharge flow rate constraint, and when the pumping station is operating, according to the dynamic reservoir capacity control strategy, the forward feasible interval of the reservoir capacity and the backward feasible interval of the reservoir capacity are deduced during the scheduling period, and the intersection of the above intervals is obtained to get the reservoir capacity feasible region [V s,1 ,V s,1 , [V s,T+1 ,V s,T+1 . Among them, V s,1 is the initial reservoir capacity of reservoir s at the first period, is the lower limit of the initial reservoir capacity feasible region of reservoir s at the second period, is the upper limit of the initial reservoir capacity feasible region of reservoir s at the second period, is the lower limit of the initial reservoir capacity feasible region for reservoir s in the t-th period, is the upper limit of the initial reservoir capacity feasible region for reservoir s in the t-th period, is the lower limit of the initial reservoir capacity feasible region for reservoir s in the T-th period, is the upper limit of the initial reservoir capacity feasible region for reservoir s in the T-th period, V s,T+1 is the final reservoir capacity of reservoir s in the T-th period.

[0099] Step 5: Conduct two-stage optimization for power station s in periods t and t + 1. First, fix V s,1 , V s,3 , and optimize V s,2 within the dynamic feasible region. When the pumping stations in both the t-th and (t + 1)-th periods are shut down, go to Step 6; otherwise, go to Step 7. Among them, V s,1 , V s,2 , and V s,3 are the initial reservoir capacities of reservoir s in the 1st, 2nd, and 3rd periods respectively,

[0100] Step 6: The decision variables in the t-th and (t + 1)-th periods are the reservoir capacities. With the goal of minimizing the mean square deviation of the remaining load of the entire power grid scheduling period, conduct discrete reservoir capacity optimization within the dynamic feasible region.

[0101] Step 7: The decision variables in the t-th and (t + 1)-th periods are the reservoir capacities, the pumping flow rate, and the operating power of the energy storage pumping station. It is necessary to conduct a trial calculation of the operation process of the pumping station. If hydropower station s is only the upper reservoir or the lower reservoir of the energy storage pumping station, conduct the first-stage trial calculation. Fix the pumping flow rate, working head, and operating power of energy storage pumping station s, and conduct a trial calculation of energy storage pumping station s - 1. The trial calculation steps are as follows: ① Assume the pumping flow rate of the pumping station or ② Calculate the working head of the pumping station or ③ Calculate the operating power of the pumping station or ④ Use the bisection method to update the pumping flow rate to or or and return to ②; ⑤ or Stop the iteration when it reaches. If hydropower station s is both the upper reservoir of energy storage pumping station s and the lower reservoir of energy storage pumping station s - 1, then go to Step 8.

[0102] Step 8: Two-stage trial calculation. In the first stage, fix the pumping flow rate, working head, and operating power of energy storage pumping station s, and conduct a trial calculation of energy storage pumping station s - 1; in the second stage, fix the trial calculation results of energy storage pumping station s - 1 and conduct a trial calculation of energy storage pumping station s.

[0103] Step 9: After performing two-stage optimization on power station s and related energy storage pumping stations for time periods t and t+1, update the initial solution based on the optimization results. If t < T-1, set t = t+1 and perform two-stage optimization for the next time period; if t = T-1, proceed to Step 10.

[0104] Step 10: If s < S, set s = s+1, t = 1, and go back to Step 5 to perform two-stage optimization for the downstream power station and related energy storage pumping stations; otherwise, proceed to Step 11.

[0105] Step 11: If k < k max , set k = k+1, t = 1, and s = 1, then go back to Step 5 to perform the next round of iterative optimization; if k = k max , the optimization process ends, and output the result information such as the remaining grid load, hydropower station output, and operating power of the energy storage pumping station for different time periods.

[0106] S4. Propose a comprehensive risk-benefit evaluation system that takes into account multi-dimensional objectives at both the system scheduling level and the power station operation level, and deeply analyze the impact of adding energy storage pumping stations on grid risks and benefits;

[0107] At the whole-system level, divide the benefits into power generation benefits and peak shaving benefits. Select power generation volume, power generation benefits, peak-valley difference of the remaining grid load, average value of the remaining grid load, mean square deviation of the remaining grid load, and the amount of abandoned electricity consumed by the pumping station as comprehensive benefit evaluation indicators, and select the amount of abandoned electricity, abandonment rate, reservoir water level fluctuation coefficient, and difference coefficient of reservoir discharge flow as comprehensive risk evaluation indicators. Specifically as follows:

[0108] Power generation volume:

[0109]

[0110] Among them, E is the total power generation volume of cascade hydropower stations during the scheduling period; N s,t is the output of hydropower station s at the t-th time period; T is the number of time periods during the scheduling period; n is the number of hydropower stations.

[0111] Power generation benefits:

[0112]

[0113] Among them, B is the total power generation benefit of cascade hydropower stations during the scheduling period; C t is the on-grid electricity price at the t-th time period.

[0114] Peak-valley difference of the remaining load:

[0115] L d =P max -P min (22)

[0116] Among them, L dThe peak-valley difference of the remaining load of the power grid during the scheduling period; P max The maximum value reached by the remaining load of the power grid during the scheduling period; P min The minimum value reached by the remaining load of the power grid during the scheduling period.

[0117] Average value of the remaining load:

[0118] P t = P t G - P t W - P t S - P t H + P t P (23)

[0119] Wherein, P t is the remaining load of the power grid at time t; P t G , P t W , P t S , P t H are respectively the load command, the total wind power output, the total photovoltaic power output, and the total hydropower output of the power grid at time t; P t P is the sum of the operating powers of the energy storage pump stations at time t.

[0120] Standard deviation of the remaining load:

[0121]

[0122] Wherein, F is the standard deviation of the remaining load of the power grid; P t is the remaining load of the system at time t.

[0123] Wind and light abandoned power consumed by the pump station:

[0124]

[0125] Wherein, E pump is the wind and light abandoned power consumed by the pump station during the scheduling period; is the wind and light abandoned power consumed by pump station s in the t-th period; m is the number of energy storage pump stations.

[0126] Abandoned power:

[0127]

[0128] Wherein, E ab is the wind and light abandoned power during the scheduling period; They are the curtailment amounts of wind power and photovoltaic power in the t period respectively.

[0129] Curtailment rate:

[0130] R ab = E ab / (E W + E S ) (27)

[0131] Among them, R ab is the curtailment amount of wind and light during the scheduling period; E ab is the curtailment amount of wind and light during the scheduling period; E W , E S are the total power generation amounts of wind power and photovoltaic power during the scheduling period respectively.

[0132] Reservoir water level fluctuation coefficient:

[0133]

[0134] Among them, CVL is the reservoir water level fluctuation coefficient during the scheduling period; L t is the reservoir water level at the t-th moment; is the average reservoir water level during the scheduling period.

[0135] Reservoir discharge flow difference coefficient:

[0136]

[0137] Among them, CV Q is the reservoir discharge flow difference coefficient. The smaller the CV Q value, the more stable the reservoir water discharge; is the reservoir discharge flow at the t-th moment; is the average value of the discharge flow.

[0138] Taking the cascade hybrid pumped-storage power station formed by adding energy storage pump stations to Longyangxia, Laxiwa, and Nina hydropower stations in the upper reaches of the Yellow River as an example, the above scheduling method is applied for analysis. The parameters of each hydropower station are shown in Table 1, and the parameters of each energy storage pump station are shown in Table 2. It should be noted that the above hydropower stations must give priority to obeying the requirements of the Yellow River water volume scheduling, that is, the comprehensive utilization requirements such as irrigation, ice flood prevention, flood control, and water supply are superior to power generation. The specific parameters of the cascade hydropower stations are shown in Table 1.

[0139] Table 1 Parameters of cascade hydropower stations

[0140]

[0141] Table 2 Parameters of energy storage pump stations

[0142]

[0143]

[0144] By applying the above short-term scheduling technology for cascade hybrid pumped storage power stations based on adding pumping stations, and setting cascade hydropower stations without energy storage pumping stations as a comparison strategy. A typical week in the dry season is selected to calculate the peak shaving effect and wind-solar accommodation index of the two schemes (see Table 3). Compared with the cascade hydropower station scheme, the mean square deviation, peak-valley difference, and mean value of the remaining load of the cascade hybrid pumped storage power station scheme are significantly reduced. Among them, the reduction rate of the mean square deviation of the remaining load reaches 49.26%, which indicates that the cascade hybrid pumped storage power station has a good peak shaving effect. When the new energy output is large or the power transmission is limited, the cascade hybrid pumped storage power station consumes part of the wind-solar abandoned power to drive the energy storage pumping station for pumped storage, reducing the wind-solar abandonment rate from 28.34% to 17.70%. At the same time, the pumping of the pumping station increases the available water volume of the upper hydropower station, increasing the hydropower generation from 260 million kW·h to 293 million kW·h. It can be seen that through the combined dispatching operation of the cascade hydropower station and the energy storage pumping station, the peak shaving effect of the system and the accommodation level of wind-solar new energy can be significantly improved.

[0145] Table 3 Comparison of typical week indicators in the dry season

[0146]

[0147] The present invention also provides a short-term scheduling system for a cascade hybrid pumped storage power station based on adding pumping stations, including:

[0148] A dynamic control strategy unit, which is used to add an energy storage pumping station between cascade series hydropower stations and adopt a dynamic control strategy for the reservoir storage capacity of the cascade hybrid pumped storage power station. According to the inflow and outflow of the hydropower station in the current period, the pumping flow rate and pumping duration of two adjacent energy storage pumping stations, the storage capacity constraint is dynamically formulated;

[0149] A scheduling model construction unit, which is used to construct a short-term scheduling model for a cascade hybrid pumped storage power station based on adding an energy storage pumping station with the minimum mean square deviation of the remaining load of the power grid as the goal. On the basis of meeting the conventional constraint conditions, the scheduling model also introduces constraints on pumping station energy consumption, pumping flow rate, and pumping station working power;

[0150] The scheduling model solving unit is used to construct a decoupling and coordination mechanism based on the improved Progressive Optimization Algorithm (POA) for the coupling relationship among the pumping flow rate, operating power of the cascade energy storage pumping station, and the water levels of the upstream and downstream reservoirs, and solve the scheduling model. For the improved POA, in the initial solution generation stage, based on the objective function of minimizing the mean square error of the remaining load, the hydropower station releases water following the remaining load of the power grid during the pump station shutdown period. In the feasible region generation stage, a dynamic feasible region generation strategy for reservoir capacity that combines forward and backward calculations is adopted. During the pump station shutdown period, according to the water balance constraint, and during the pump station operation period, according to the dynamic control strategy of reservoir capacity, a dynamic feasible region within the scheduling period is formed. For the operating conditions involving multiple decision variables, two-stage trial calculations are carried out, that is, the pumping flow rate, working head, and operating power of the upper and lower energy storage pump stations of the current hydropower station are fixed respectively.

[0151] The evaluation unit is used to construct a comprehensive risk-benefit evaluation system, taking into account the multi-dimensional objectives at the system scheduling level and the power station operation level, and deeply analyze the impact of adding an energy storage pump station on the power grid risk and benefit.

Claims

1. A short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations, characterized in that, It includes the following steps: Add an energy storage pumping station between cascade hydropower stations, and adopt a dynamic control strategy for the reservoir storage capacity of the cascade hybrid pumped-storage power station to dynamically formulate the storage capacity constraint; Construct a short-term scheduling model for the cascade hybrid pumped-storage power station with an added energy storage pumping station aiming at minimizing the mean square deviation of the remaining load of the power grid; Based on the improved Progressive Optimization Algorithm (POA), aiming at the coupling relationship between the pumping flow rate, operating power of the cascade energy storage pumping station and the water levels of the upstream and downstream reservoirs, construct a decoupling and coordination mechanism to solve the scheduling model. In the improved POA, in the initial solution generation stage, based on the objective function of minimizing the mean square deviation of the remaining load, the hydropower station tracks the remaining load of the power grid and discharges water during the shutdown period of the pumping station; in the feasible region generation stage, adopt a dynamic feasible region generation strategy for the storage capacity that combines forward and backward deductions. According to the water balance constraint during the shutdown period of the pumping station and the dynamic control strategy for the storage capacity during the working period of the pumping station, form a dynamic feasible region within the scheduling period; for the working conditions involving multiple decision variables, adopt a two-stage trial calculation, that is, fix the pumping flow rate, working head and operating power of the upper and lower energy storage pumping stations of the current hydropower station respectively; Construct a comprehensive risk-benefit evaluation system, taking into account the multi-dimensional objectives at the system scheduling level and the power station operation level, and deeply analyze the impact of adding an energy storage pumping station on the risks and benefits of the power grid.

2. The short-term scheduling method of the cascade hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that After adding an energy storage pumping station between cascade hydropower stations, the dynamic control strategy for the reservoir storage capacity follows the following water balance relationship: Among them, V s,t-1 ′ and V s,t ′ are the initial and final reservoir storage capacities of hydropower station s at the beginning and end of the t-th period after adding an energy storage pumping station, respectively; and are the water inflow and outflow of hydropower station s during the t-th period after adding an energy storage pumping station, respectively; I s,t , are the natural inflow, power generation flow, and water discharge flow of hydropower station s during the t-th period, respectively; is the outflow of hydropower station s-1 during the (t - τ)-th period; τ is the water flow lag time between the s-th and (s + 1)-th reservoirs; △t is the period length; is the pumping flow of pumping station s from reservoir s + 1 to reservoir s during the t-th period; is the pumping flow of pumping station s from reservoir s to reservoir s-1 during the t-th period; α s , α s-1 are both binary variables. When an energy storage pumping station is added between hydropower station s and hydropower station s + 1, α s = 1, otherwise α s = 0; when an energy storage pumping station is added between hydropower station s-1 and hydropower station s, α s-1 = 1, otherwise α s-1 = 0.

3. The short-term scheduling method of the cascade hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that During the pumping operation of the energy storage pumping station, dynamically formulate the storage capacity constraint, and the storage capacity constraint is: Among them, V s,t is the end storage capacity of reservoir s at the t-th time period; are the storage capacities corresponding to the dead water level and the normal storage level of reservoir s respectively; are the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pump station s respectively; are the maximum allowable pumping flow rate and the minimum allowable pumping flow rate of pump station s-1 respectively; T p is the continuous pumping duration starting from time period t.

4. The short-term scheduling method of the cascade hybrid pumped storage power station based on adding pumping stations according to claim 1, characterized in that The objective function of the short-term scheduling model for the cascade hybrid pumped-storage power station with an added energy storage pumping station is: where, σ is the mean square deviation of the remaining load; t is the time period, t = 1, 2, 3, ..., T, and T is the number of time periods within the scheduling period; P t represents the remaining load of the system at time period t; represents the average value of the remaining load; are the load instruction, total wind power output, total photovoltaic power output, and total hydropower station output of the power grid at time period t, respectively; is the sum of the operating powers of the energy storage pump stations at time period t.

5. The short-term scheduling method of the cascade hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that After adding an energy storage pumping station between cascade hydropower stations, on the basis of meeting the conventional constraint conditions, the scheduling model also introduces a number of new physical and operating constraints, including the pump station energy consumption constraint, the pumping flow rate constraint and the pump station working power constraint; specifically as follows: Pump station power consumption constraint: Among them, is the operating power of pumping station s at the t-th time period; is the working head of pumping station s at the t-th time period; ρ is the density of the pumped liquid; g is the acceleration due to gravity; η s is the overall efficiency of pumping station s; is the motor efficiency of pumping station s; is the pump efficiency of pumping station s; is the pressure pipeline efficiency of pumping station s; Pumping flow rate constraint: Among them, is the pumping flow rate of pumping station s at the t-th time period; is the minimum allowable pumping flow rate of pumping station s; is the maximum allowable pumping flow rate of pumping station s at the t-th time period; are respectively the maximum pumping flow rate of the lower reservoir of pumping station s with "water available for pumping" and the maximum pumping flow rate of the upper reservoir of pumping station s with "reservoir available for storage"; is the inflow water volume of hydropower station s + 1 at the t-th time period; is the minimum discharge flow rate of hydropower station s + 1; is the minimum allowable reservoir capacity of the lower reservoir of pumping station s + 1 under the reservoir capacity control strategy at time period t; V s+1,t is the reservoir capacity of the lower reservoir of pumping station s + 1 at time period t; is the inflow water volume of hydropower station s at the t-th time period; is the minimum discharge flow rate of hydropower station s; is the maximum allowable reservoir capacity of the upper reservoir of pumping station s under the reservoir capacity control strategy at time period t; V s,t is the reservoir capacity of the lower reservoir of pumping station s at time period t; Pump station working power constraint: Among them, is the working power of pumping station s at time period t; is the minimum allowable working power of pumping station s; is the maximum allowable working power of pumping station s; is a binary variable representing the operating state of pumping station s at time period t.

6. The short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations according to claim 1, wherein The initial solution of the cascade hydropower station in the improved Progressive Optimization Algorithm is: Among them, is the discharge flow of the s-th power station at the t-th time period calculated from the initial solution; is the total discharge flow corresponding to the total available water volume obtained by the s-th power station during the calculation period; P s,t is the remaining load faced by the s-th power station at the t-th time period; P min is the minimum value of the remaining load after the regulation of the hydropower station; is the minimum discharge flow of the hydropower station s.

7. The short-term scheduling method for a cascaded hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that The cascade hydropower station calculates the initial and final reservoir capacities according to the water level-reservoir capacity relationship. When the pump station stops operating, it is based on the water balance equation and the downstream discharge constraint. When the pump station is working, it is based on the dynamic control strategy of the reservoir capacity. During the scheduling period, the forward feasible interval of the reservoir capacity and the backward feasible interval of the reservoir capacity are deduced, and the intersection of the above intervals is obtained to get the feasible region of the reservoir capacity [V s,1 ,V s,1 , [V s,T+1 ,V s,T+1 ; Among them, V s,1 is the initial storage capacity of reservoir s in the first period, are respectively the lower and upper limits of the feasible region of the initial storage capacity of reservoir s in the second period, are respectively the lower and upper limits of the feasible region of the initial storage capacity of reservoir s in the t-th period, are respectively the lower and upper limits of the feasible region of the initial storage capacity of reservoir s in the T-th period, V s,T+1 is the final storage capacity of reservoir s in the T-th period.

8. The short-term scheduling method of the cascade hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that In the improved step-by-step optimization algorithm, a trial calculation needs to be carried out on the operation process of the pumping station. If the hydropower station s is only the upper reservoir or the lower reservoir of the energy storage pumping station, the first-stage trial calculation is carried out. Fix the pumping flow rate, working head, and operating power of the energy storage pumping station s, and conduct a trial calculation on the energy storage pumping station s-1. The trial calculation steps are as follows: ① Assume the pumping flow rate of the pumping station or ② Calculate the working head of the pumping station or ③ Calculate the operating power of the pumping station or ④ Use the bisection method to update the pumping flow rate to or or and then return to ②; ⑤ or Stop the iteration when it reaches this point; If hydropower station s is both the upper reservoir of energy storage pumping station s and the lower reservoir of energy storage pumping station s-1, then transfer to the two-stage trial calculation; in the first stage, fix the pumping flow rate, working head and operating power of energy storage pumping station s, and conduct a trial calculation on energy storage pumping station s-1; in the second stage, fix the trial calculation results of energy storage pumping station s-1 and conduct a trial calculation on energy storage pumping station s.

9. The short-term scheduling method of the cascade hybrid pumped-storage power station based on adding pumping stations according to claim 1, characterized in that The constructed comprehensive risk-benefit evaluation system includes: selecting power generation volume and power generation benefit, the peak-valley difference of the remaining load of the power grid, the mean value of the remaining load of the power grid, the mean square deviation of the remaining load of the power grid, and the abandoned electricity consumption of the pump station as comprehensive benefit evaluation indicators, and selecting the abandoned electricity volume, abandoned electricity rate, reservoir water level fluctuation coefficient, and reservoir discharge flow difference coefficient as comprehensive risk evaluation indicators.

10. A short-term scheduling system for a cascaded hybrid pumped-storage power station based on adding pumping stations, characterized in that, It includes: A dynamic control strategy unit for adding an energy storage pumping station between cascade hydropower stations and adopting a dynamic control strategy for the reservoir storage capacity of the cascade hybrid pumped-storage power station to dynamically formulate the storage capacity constraint; A scheduling model construction unit for constructing a short-term scheduling model for the cascade hybrid pumped-storage power station with an added energy storage pumping station aiming at minimizing the mean square deviation of the remaining load of the power grid; The scheduling model solving unit is used to construct a decoupling and coordination mechanism and solve the scheduling model for the coupling relationship among the pumping flow rate, operating power of the cascade energy storage pump station, and the water levels of the upstream and downstream reservoirs based on the improved Progressive Optimization Algorithm (POA). In the improved POA, in the initial solution generation stage, based on the objective function of minimizing the mean square error of the remaining load, the hydropower station releases water following the remaining load of the power grid during the pump station shutdown period. In the feasible region generation stage, a dynamic feasible region generation strategy for reservoir storage that combines forward and backward calculations is adopted. During the pump station shutdown period, a water balance constraint is used, and during the pump station operation period, a dynamic control strategy for reservoir storage is adopted to form a dynamic feasible region within the scheduling period. For operating conditions involving multiple decision variables, a two-stage trial calculation is used, that is, the pumping flow rate, working head, and operating power of the upper and lower energy storage pump stations of the current hydropower station are fixed respectively. The evaluation unit is used to construct a comprehensive risk-benefit evaluation system, taking into account multi-dimensional objectives at both the system scheduling level and the power station operation level, and deeply analyzing the impact of adding an energy storage pump station on the risks and benefits of the power grid.

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