A capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station

Abstract

The present invention discloses a method for capacity configuration of a conventional hydropower station transformation combined with a pure pumped-storage power station, and relates to the technical field of power systems. The method comprises: obtaining basic parameters; the basic parameters include operating parameters of each unit and system; inputting the basic parameters into a coordinated configuration model of a pure storage and hybrid storage power station, and performing configuration optimization using the installed capacity and number of pumped storage units added to the hydropower station, the installed capacity and number of units of the pure storage power station, and the storage capacity of the upper reservoir as quantities to be planned, to obtain a final planning scheme; the coordinated configuration model of the pure storage and hybrid storage power station is constructed based on an objective function, a power station model, constraints, inertia requirements, and a scenario method optimization; the power station model includes a pure pumped-storage power station model, a hybrid pumped-storage power station model, and the corresponding operating constraints of each model. The present invention can ensure that the configured capacity meets the flexibility and safety requirements of the system under different circumstances.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a capacity configuration method for transforming a conventional hydropower station into a combined pure pumped-storage power station. Background Art

[0002] The integration of renewable energy into the grid presents uncertainties in output and an inability to provide inertia support during system disturbances, hindering its development. Therefore, there is an urgent need to flexibly adjust resources to support renewable energy output. Hydropower is a crucial resource for ensuring the safe and stable operation of the power system and the absorption of renewable energy, but limited development resources constrain hydropower planning and construction. Therefore, rationally transforming conventional hydropower to leverage its advantages of "balancing power supply and flexible regulation" is crucial to promoting the development of the renewable energy and hydropower industries.

[0003] China encourages the transformation of conventional hydropower stations and the scientific development of pumped-storage power plants. As a green, regulating power source with mature technology and scalable scale, pumped-storage power plants play a key role in promoting renewable energy as a major source of electricity and ensuring the stable development of the power system. Therefore, rationally planning the capacity of pumped-storage power plants is crucial to ensuring their efficient operation and enhancing system flexibility.

[0004] Hybrid pumped-storage power stations (referred to as "hybrid storage" power stations) are built based on hydropower, with lower investment costs and the advantages of both quantity and regulation, but their transformation potential is limited and their operating conditions are complex; pure pumped-storage power stations (referred to as "pure storage" power stations) have flexible operating modes, but their investment costs are high and they cannot undertake power generation tasks. Therefore, through joint planning of the two, their advantages can be complementary to ensure stable operation of the system.

[0005] Current research on hybrid-storage power plants primarily focuses on directly retrofitting existing hydropower plants, analyzing their advantages during operation, but lacks research on the impact of the scale of the retrofit on the system. Furthermore, due to the limited scale of conventional hydropower plants that can be retrofitted, planning hybrid-storage power plants alone may not meet system requirements. Considering the combined planning of hybrid and pure-storage power plants, the impact of the capacity of both configurations on system operation urgently needs to be studied. Furthermore, current analysis of pumped storage planning primarily focuses on economic rationality, while ignoring its ability to provide inertia support and ensure system safety. Summary of the Invention

[0006] The purpose of the present invention is to provide a capacity configuration method for a conventional hydropower station combined with a pure pumped storage power station, which can ensure that the configured capacity meets the flexibility and safety requirements of the system under different conditions.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station, comprising:

[0009] Obtaining basic parameters; the basic parameters include operating parameters of each unit and system;

[0010] The basic parameters are input into the coordinated configuration model of pure-storage and hybrid-storage power stations, and the installed capacity and number of pumped-storage units added to the hydropower station, the installed capacity and number of units of the pure-storage power station, and the storage capacity of the upper reservoir are used as the planned quantities for configuration optimization to obtain the final planning scheme; the coordinated configuration model of pure-storage and hybrid-storage power stations is constructed based on the objective function, power station model, constraints, inertia requirements and scenario method optimization; the power station model includes a pure pumped-storage power station model, a hybrid pumped-storage power station model and the corresponding operating constraints of each model.

[0011] Optionally, the final planning scheme is determined by:

[0012] The basic parameters of the planning year are obtained through operation simulation, and the typical daily data of the flood season and the dry season are determined through cluster analysis. The uncertainty of wind and solar power output is considered in the typical scenario data to optimize the configuration. The preliminary planning results of the pumped storage units are first obtained, and then the preliminary planning results are judged. If the set scenario data is met, the preliminary planning results are output as the final planning scheme. If the set scenario data is not met, the unsatisfactory data is added to the scenario data of the previous moment for re-planning until the final planning scheme is output.

[0013] Optionally, the objective function aims to minimize the total cost, which includes the full life cycle cost of the pumped storage power station and the system operation cost:

[0014]

[0015] Where, F op is the average system operating cost on typical days in the flood season and dry season, F inv The full life cycle cost of the pumped storage unit.

[0016] Optionally, the pure storage power station output model of the pure pumped storage power station model is:

[0017]

[0018] Where, and They are the storage and release water volumes of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power output of the i-th pumped storage unit at time t; η c and η d are the pumping efficiency and power generation efficiency of the pumped storage unit; ρ is the water density; g is the acceleration of gravity; h is the average head; N2 is the planned number of pumped storage units in the pure storage power station.

[0019] Optionally, the operating constraints corresponding to the pure storage power station output model include output limit constraints, first storage capacity constraints and spinning reserve constraints.

[0020] Optionally, the conventional hydropower unit output model of the hybrid pumped storage power station model is:

[0021]

[0022] Where: is the power generated by the i-th hydropower unit at time t; is the power generation flow of the hydropower unit; H i,t is the generating head of the hydropower unit; η is the generating efficiency.

[0023] Optionally, the operating constraints corresponding to the conventional hydropower unit output model include upper and lower reservoir constraints, second storage capacity constraints, water level fluctuation constraints and hydropower unit constraints; wherein, the hydropower unit constraints include output constraints, vibration zone constraints, generating head constraints, climbing constraints and output operating condition constraints between pumped storage power station units.

[0024] Optionally, the constraint conditions include power balance constraint, line transmission capacity constraint and quasi-steady-state frequency constraint.

[0025] Optionally, the typical scene data is generated using a scene method, and the data generated and reduced using the scene method is:

[0026]

[0027] Where: P new,α 、P L,α is the new energy power and load value under the αth scenario; P newpre 、P Lpre is the power prediction value under the basic scenario; is the power prediction error value under the αth scenario.

[0028] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0029] The present invention discloses a method for configuring the capacity of a conventional hydropower station combined with a pure pumped-storage power station. The method comprises obtaining basic parameters; the basic parameters include operating parameters of each unit and the system; inputting the basic parameters into a coordinated configuration model for pure storage and hybrid storage power stations, and optimizing the configuration using the installed capacity and number of pumped storage units added to the hydropower station, the installed capacity and number of units of the pure storage power station, and the storage capacity of the upper reservoir as quantities to be planned, thereby obtaining a final planning scheme; the coordinated configuration model for pure storage and hybrid storage power stations is constructed based on an objective function, a power station model, constraints, inertia requirements, and a scenario method optimization method; the power station model includes a pure pumped-storage power station model, a hybrid pumped-storage power station model, and the corresponding operating constraints of each model. The present invention takes into account the operating characteristics of different types of pumped-storage power stations and the minimum inertia requirement after system disturbances, thereby obtaining the configuration results of the hybrid storage and pure storage power stations with the minimum total system cost, and optimizes the configuration results using data from different scenarios to ensure that the configured capacity meets the flexibility and safety requirements of the system under different circumstances. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 This is a schematic diagram of the overall operation and planning of the system in this embodiment;

[0032] Figure 2 Schematic diagram of peak load regulation and inertia support of the pumped storage power station in this embodiment;

[0033] Figure 3 This is a schematic diagram of the model solution process in this embodiment;

[0034] Figure 4 Schematic diagram of the system inertia during the wet season and the dry season in this embodiment; wherein, part (a) is a schematic diagram of the wet season; part (b) is a schematic diagram of the dry season;

[0035] Figure 5 Schematic diagram of the system initial frequency change rate during the flood season and dry season considering inertia demand in this embodiment; wherein, part (a) is a schematic diagram of the flood season; part (b) is a schematic diagram of the dry season;

[0036] Figure 6 Schematic diagram of the system initial frequency change rate and unit start-up and shutdown status during the flood season when inertia demand is not considered in this embodiment; part (a) is a schematic diagram of the frequency change rate; part (b) is a schematic diagram of the unit start-up and shutdown status;

[0037] Figure 7 Schematic diagram of the initial frequency change rate and the start-stop state of the pumped storage unit in scenario 1 of this embodiment; wherein, part (a) is a schematic diagram of the frequency change rate; part (b) is a schematic diagram of the start-stop state of the unit;

[0038] Figure 8 Schematic diagram of the initial frequency change rate and the start-stop state of the pumped storage unit in scenario 6 of this embodiment; wherein, part (a) is a schematic diagram of the frequency change rate; part (b) is a schematic diagram of the start-stop state of the unit;

[0039] Figure 9 Schematic diagrams of the operating power of the hydropower units and pumped storage units in scenarios 1 and 6 of this embodiment; wherein, part (a) is a schematic diagram of scenario 1; part (b) is a schematic diagram of scenario 6;

[0040] Figure 10 This is a schematic diagram of the total cost and construction cost of different installed capacity ratios of the hybrid storage and pure storage power stations in this embodiment. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] The purpose of the present invention is to provide a capacity configuration method for a conventional hydropower station combined with a pure pumped storage power station, which can ensure that the configured capacity meets the flexibility and safety requirements of the system under different conditions.

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] In response to the above problems, the present invention proposes a capacity planning method for conventional hydropower integration and transformation combined with the construction of a new pure pumped-storage power station. While coping with the complex working conditions of the hybrid storage power station and reducing the construction cost of the pure storage power station, it also takes into account the system inertia demand to ensure its economical and safe operation. First, the planning year data is obtained by operation simulation, and the minimum system inertia that meets the frequency safety constraints is calculated based on the clustered typical data of the flood season and the dry season; secondly, the hybrid pumped storage power station and the pure pumped storage power station of the hydropower transformation are jointly planned and modeled, and the minimum inertia demand of the system is incorporated, and the preliminary planning results are obtained with the minimum total cost as the goal; in order to ensure that the planning scheme effectively responds to the uncertainty of new energy, the scenario method is used to optimize the configuration results to meet the operating requirements under different circumstances. Finally, the case analysis shows that the coordinated planning of the two can effectively reduce the construction cost of the pure pumped storage power station and improve the flexibility of the system, while ensuring that the frequency index of the system after disturbance is within a reasonable range.

[0045] The present invention provides a capacity configuration method for a conventional hydropower station transformation combined with a pure pumped storage power station, comprising:

[0046] Obtain basic parameters; the basic parameters include operating parameters of each unit and system.

[0047] The basic parameters are input into the coordinated configuration model of pure-storage and hybrid-storage power stations, and the installed capacity and number of pumped-storage units added to the hydropower station, the installed capacity and number of units of the pure-storage power station, and the storage capacity of the upper reservoir are used as the planned quantities for configuration optimization to obtain the final planning scheme; the coordinated configuration model of pure-storage and hybrid-storage power stations is constructed based on the objective function, power station model, constraints, inertia requirements and scenario method optimization; the power station model includes a pure pumped-storage power station model, a hybrid pumped-storage power station model and the corresponding operating constraints of each model.

[0048] As a more specific implementation method, the following steps are included:

[0049] Step 1: System inertia requirements and joint planning analysis of different types of pumped storage power stations

[0050] 1. System inertia requirement analysis

[0051] When a disturbance occurs, the system maintains stability through the inertia response process. Even if renewable energy generation can provide virtual inertia through control measures, the uncertainty of renewable energy output can make system regulation difficult or cause insufficient inertia. Therefore, pumped storage power stations are planned to provide the system with the inertial kinetic energy required for disturbance resistance. Factors affecting the required inertia of the system include the rate of change of frequency (RoCoF) and the lowest frequency point. The formula for the dynamic frequency change process is as follows:

[0052]

[0053] Where f0 is the rated frequency of the system; Δf is the frequency deviation; D sys is the damping coefficient in the system; ΔP loss is the system disturbance power; ΔP is the power increment of the unit in the system; H e It is the overall inertia of the system, which is related to the number of units in operation and the total installed capacity in the system.

[0054] Since photovoltaic power plants need to cooperate with energy storage power stations to participate in frequency regulation, the new energy of this invention only considers the virtual inertia provided by wind power and uses an equivalent model to calculate its virtual inertia time constant. The formula is as follows:

[0055]

[0056] Where H w is the virtual inertia time constant of the wind farm; H w,i is the virtual inertia time constant of the i-th wind turbine; P wN is the total installed capacity of the wind farm; N w is the number of wind turbines in the wind farm.

[0057] Since the speed and frequency of the pumped storage unit are decoupled, it can participate in the system inertia support through control means or virtual inertia. At the same time, the inertia of different generators in the system is concentrated into an equivalent system inertia, the formula is as follows:

[0058]

[0059] Where H i represents the inertia constant of unit i; is the rated power of unit i; u i It is the start and stop variable of the unit.

[0060] From the above formula, we can see that the larger the capacity of the pumped storage unit, the more rotational inertia it can provide, but it will also cause excessive planning costs. It is necessary to find a balance point that takes into account the economy and safety of the system. Figure 1 By calculating the minimum inertia that meets system safety, the installed capacity and number of pumped storage units are planned to ensure that the initial frequency change rate and the lowest frequency point after the system is disturbed are within the specified range.

[0061] A sudden disturbance in the system generates unbalanced power, causing the system frequency to change. At the moment of the disturbance, the frequency change is zero, and the frequency rate of change reaches its maximum value. To prevent the frequency rate of change from exceeding the specified value after a disturbance, potentially compromising system safety, the units in the system must have sufficient inertia. The frequency rate of change formula is as follows: its magnitude is inversely proportional to the system's inertia.

[0062]

[0063] Where, RoCoF max is the maximum allowable frequency change rate.

[0064] The calculation of the lowest frequency point can be performed by simulation or numerical methods. The numerical methods include a ramp model, a dynamic response model, and a response time model. The model used in the present invention depends on the system inertia, the unit ramp rate, and the dead zone frequency.

[0065]

[0066] Where, P i x is the unit's spare capacity; r is the unit's ramp power; Δf db is the dead zone frequency of the unit; f UFLS is the minimum frequency allowed by the system; G is the set of spinning standby units.

[0067] 2. Analysis of the structure and joint planning of pure storage and hybrid storage power stations

[0068] Conventional hydropower stations can be transformed into hybrid hydropower stations by adding pumped-storage units, achieving a functional shift from one-way power generation to two-way regulation. Hybrid hydropower stations fully utilize water resources to improve system operational flexibility and economic efficiency. However, after transformation, the operating conditions and water conditions between the units become more complex, and the internal nonlinear characteristics are complex. Furthermore, the scale of the hydropower station limits the capacity of additional pumped-storage units. Therefore, consideration is given to simultaneously planning a pure hydropower station, with both providing flexible regulation capabilities and inertia support for the system.

[0069] Depend on Figure 2 It can be seen that during load peaks, the hybrid and pure storage power stations are in power generation conditions. At this time, the units in the pure storage power station and the hybrid storage power station can be started, alleviating the peak-shaving pressure while providing inertia support for the system; during load valleys, the hybrid and pure storage power stations are in pumping conditions. However, due to the influence of internal operating constraints, the hybrid storage power station has only the hydropower units that undertake daily power generation tasks in the start-up state, and the other hydropower units cannot be started. Therefore, only some units in the pure storage and hybrid storage power stations provide inertia support; if the hydropower of the hybrid storage power station undertakes the power generation task, at this time there is surplus wind and solar power or the system is disturbed, the pumped storage units cannot be started due to the internal operating constraints of the hybrid storage power station. At this time, the pure storage power station can be used to adjust the system fluctuations to absorb new energy and provide inertia support.

[0070] In summary, by coordinating the planning of hybrid and pure-storage power stations, we can address the limitations of the hybrid power station's own construction scale and eliminate the impact of complex internal working conditions. At the same time, we can reduce the high construction cost of pure-storage power stations, provide sufficient inertial response in the event of sudden disturbances in the system, enhance the system's anti-disturbance capability, and ensure the safety of the system's power supply.

[0071] Step 2: Joint planning model for hydropower transformation and pure storage power stations

[0072] A coordinated configuration model for pure-storage and hybrid-storage power stations was established. The planned quantities included the installed capacity and number of pumped-storage units added to the hydropower station, the installed capacity and number of units in the pure-storage power station, and the upper reservoir capacity. To simplify calculations, the annual data for both the high-water and low-water periods were clustered to form typical daily data. This data was then used to configure the appropriate installed capacity of the pumped-storage power station. However, planning results based solely on typical days may not meet the diverse operating conditions of the system. Therefore, to ensure the universality of the final planning results, the preliminary planning results were subsequently optimized through scenario analysis to ensure that the planned pumped-storage power station can effectively cope with the uncertainties of renewable energy.

[0073] 1. Objective Function

[0074] The planning goal is to minimize the total cost, which includes the full life cycle cost of the pumped storage power station and the system operation cost:

[0075]

[0076] Where, F op is the average system operating cost on typical days in the flood season and dry season, F inv The full life cycle cost of the pumped storage unit.

[0077]

[0078] Where, F ci 、F cm 、F cd are the annual investment cost, maintenance cost, and replacement cost of the pumped storage power station respectively; when s is 1, it is the flood season, and when s is 2, it is the dry season; C s,h 、C s,hy 、C s,pump 、C s,cur 、C s,x The variables in the formula are for a single scenario.

[0079]

[0080] Where, P 1,i,max 、P 2,i,max They are the installed capacity of a single unit of the planned hybrid storage and pure storage power stations respectively; is the planned capacity of the reservoir of the pure storage power station; ρ1 and ρ2 are the unit installed capacity investment costs, and ρ3 is the unit capacity investment cost α of the upper reservoir of the pure storage power station m is the annual maintenance rate; γ is the discount rate; Y is the life cycle of the pumped storage power station; α dis the replacement rate; N1 and N2 are the planned numbers of pumped storage units in hybrid storage and pure storage power stations respectively.

[0081]

[0082] Where λ 1,i and λ 2,i 0-1 variables representing whether unit i is put into construction, 1 means it is put into construction, and 0 means it is not put into construction; P1 and P2 are the planned installed capacity of each unit of the two power stations; P 1,max 、P 1,min are the minimum and maximum installed capacities of a single hybrid storage power station; P 2,max 、P 2,min They are respectively the minimum and maximum installed capacity of a single pure storage power station.

[0083] The Big M method is used to linearize the multiplication of the 0-1 variable and the continuous variable in the above formula, and the intermediate variable y is used. 1,i .

[0084]

[0085] The above formula expresses the variable y 1,i Replaces the term that multiplies a Boolean variable by a continuous variable. M is a large constant term.

[0086]

[0087] Where C h is the operating cost of thermal power units; C hqt is the start-up and shutdown cost of the thermal power unit, and the subsequent start-up and shutdown cost formula is the same; U i,t is the start / stop status of the i-th unit at time t, which is a 0-1 variable; C h,i is the unit start-up and shutdown cost of the i-th unit; C h,i is the power generation capacity of the i-th thermal power unit at time t; a i 、b i 、c i is the coal consumption characteristic coefficient of the i-th unit.

[0088]

[0089] Where C hy The operating cost of the hydropower unit; is the start-up and shutdown cost of the hydropower unit; ω hy is the hydropower operation and maintenance cost coefficient.

[0090]

[0091] Where C pump is the operating cost of the pumped storage unit; is the start-up and shutdown cost of the pumped storage power station; since the pumped storage power station recovers the variable cost of peak regulation through the electricity price, the profit coefficients α1 and α2 are considered to quantify the operating profit of the pumped storage power station; G e is the benchmark price for coal-fired power generation; η z is the comprehensive power generation efficiency of the pumped storage unit; They are the pumping power of the hybrid storage power station and the generating power of the pure storage power station respectively.

[0092]

[0093] Where C cur is the penalty cost for power curtailment; ξ is the penalty cost per unit of power curtailment; and Power prediction for wind and solar power; and The actual grid power of wind and solar power.

[0094]

[0095] Where C x is the spinning reserve cost; μ1 and μ2 are the spinning reserve cost coefficients of conventional units and pumped storage units respectively; The rotating reserve capacity is provided for thermal power, hydropower, pumped storage units of pure storage power stations and pumped storage units of hybrid storage power stations.

[0096] 2. Pure pumped storage power station model

[0097] Pure storage power station output model:

[0098]

[0099] Where: and They are the storage and release water volumes of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power output of the i-th pumped storage unit at time t; η c and η d are the pumping efficiency and power generation efficiency of the pumped storage unit; ρ is the water density; g is the acceleration of gravity; h is the average head; N2 is the planned number of pumped storage units in the pure storage power station.

[0100] Operation constraints of pure storage power station:

[0101] Generally, the lower reservoir of a pumped-storage power station has sufficient water, so only the upper reservoir capacity is considered in planning. The operating constraints of the pumped-storage units in a hybrid power station are the same as below.

[0102] 1) Output limit constraints

[0103]

[0104] Where: and are the lower limit of the unit's extraction power; P 2,i,max It is the installed capacity of a single unit in a pure storage power station; and The start and stop variables of the pumping and generating status of the i-th pumped storage unit at time t.

[0105] 2) Storage capacity constraints

[0106]

[0107] Where: is the storage capacity of the upper reservoir of the pure storage power station at time t; and are the upper and lower limits of the reservoir capacity of the pure storage power station; W μ The above formula indicates that the planned storage capacity can ensure that the pure storage power station can generate power for 6 hours at full capacity.

[0108] 3) Spinning reserve constraints

[0109]

[0110] Where, and They are the upper and lower spinning reserves during the power generation operation of the pumped storage unit; and They are the upper and lower rotating reserves of the pumped storage unit during pumping operation.

[0111]

[0112] Where, The pumping and discharge rates for the spinning reserve of a pumped-storage power station. This represents the reservoir capacity required for the spinning reserve.

[0113] 3. Hybrid pumped storage power station model

[0114] The present invention considers adding a pumped storage unit to a conventional hydropower station to form a hybrid pumped storage power station.

[0115] Output model of conventional hydropower units:

[0116]

[0117] Where: is the power generated by the i-th hydropower unit at time t; is the power generation flow of the hydropower unit; H i,t is the generating head of the hydropower unit; η is the generating efficiency.

[0118] Hybrid power station constraints:

[0119] 1) Upper and lower reservoir constraints

[0120] Among them, u represents the upper reservoir and d represents the lower reservoir. In the following, only the variables of the upper reservoir will be introduced, and the lower reservoir will not be repeated.

[0121]

[0122] Where, is the storage capacity of the upper reservoir of the hybrid storage power station at time t; is the natural water flow at time t; and are the flow rates during water storage and power generation at time t, respectively; is the power generation flow of the hydropower unit at time t; is the power generation flow of the pumped storage unit at time t.

[0123] 2) Storage capacity constraints

[0124]

[0125] Where, is the water level of the upper reservoir and the lower reservoir at time t, and are the upper and lower limits of the reservoir capacity, respectively.

[0126] 3) Water level fluctuation constraints

[0127]

[0128] Where β represents the allowable variation range of the reservoir's initial and final capacity.

[0129] Hydropower unit constraints

[0130] 1) Output constraints

[0131]

[0132] Where, and The lower and upper limits of the hydropower generating capacity; and The lower and upper limits of the hydropower generation flow rate; It is the start and stop variable of the hydropower unit.

[0133] 2) Vibration zone constraints

[0134]

[0135] Where, and It is the upper and lower limits of the kth vibration zone of the hydropower unit, indicating that the unit output is not within the vibration zone.

[0136] 3) Power generation head constraint

[0137]

[0138] Where, is the head loss.

[0139] 4) Climbing constraints

[0140]

[0141] Where, is the maximum ramp rate of the i-th hydropower unit.

[0142] 5) Output operating condition constraints between pumped storage power station units

[0143]

[0144] Where, The two states are the start and stop of the hydropower units in the hybrid storage power station and the pumping and power generation status of the pumped storage units. This formula indicates that the pumping and power generation states of the hybrid storage power station are mutually exclusive.

[0145]

[0146] The above formula not only constrains the pumping and power generation states within the pure storage power station to be mutually exclusive, but also constrains the pumping and power generation states of the pumped storage units between the two power stations to be mutually exclusive.

[0147] 4. Other constraints

[0148] 1) Power balance constraints

[0149]

[0150] Where, is the system load; and are the pumping power of mixed storage and pure storage power stations respectively; and They are the power generation capacity of hybrid storage and pure storage power stations respectively.

[0151] 2) The line transmission capacity constraints are as follows:

[0152]

[0153] Where, is the line transmission power at time t; is the maximum transmission power of the line; θ n,t is the phase angle value of node n at time t; θ max is the maximum phase angle value; θ0 is the equilibrium node phase angle value.

[0154] 3) Quasi-steady-state frequency constraint:

[0155]

[0156] Where, is the maximum allowable frequency deviation.

[0157] 5. Linearization

[0158] The McCormick convex envelope relaxation method was used to multiply two continuous variables.

[0159]

[0160] The linearization formula of vibration zone constraint is as follows:

[0161]

[0162] Where, and are the upper and lower limits of the hydropower unit operation area; k is the number of hydropower unit operation areas, that is, the number of areas outside the vibration area; y i,t,j It is a 0-1 variable that constrains the j-th feasible region. When it is 1, it means that unit i operates in the j-th region, otherwise it is 0.

[0163] Step 3: Optimize the configuration results considering the uncertainty of wind and solar power output

[0164] Due to the uncertainty of wind and solar power output, it may cause excessive regulation pressure on the units in the system or even make them unable to be regulated. Therefore, the scenario method is used to generate five scenarios for each basic scenario. The goal is to minimize the operating cost in formula (6) to determine whether the planning results meet the operating requirements. If they do, the planning results are output; otherwise, the unsolvable scenario data are added to the basic scenario, and the capacity of the pumped storage power station is replanned to ensure that the final result can meet the different operating conditions of the system.

[0165] 1. Scene generation and reduction

[0166] Scenario analysis was used to quantify the uncertainty of wind and solar power output. Since the predicted values have certain errors, Latin hypercube sampling was used to generate 1,000 sets of data for the prediction errors. Fast predecessor elimination based on probability distance was then used to reduce these 1,000 sets of data to five scenarios. The data after scenario generation and reduction is as follows:

[0167]

[0168] Where: P new,α 、P L,α is the new energy power and load value under the αth scenario; P newpre 、PLpre is the power prediction value under the basic scenario; is the power prediction error value under the αth scenario.

[0169] New energy and load forecast errors Satisfying the normal distribution, the probability density function is as follows:

[0170]

[0171] Where: σ is the standard deviation of the forecast error of new energy and load; μ is the mean of the forecast error.

[0172] 2. Overall flow chart

[0173] The model solving process of the present invention is as follows Figure 3 By running simulations, we obtain data such as wind and solar loads for the planned year. Using clustering methods, we obtain typical daily data for the flood and dry seasons. We then determine the initial planning values for the pumped storage units under typical scenarios. We then determine whether the resulting planning values meet the operational constraints of other scenarios. If so, we output these planning values. Otherwise, we add the unsatisfactory scenario data to the base scenario and re-plan the results. This process continues until the judgment conditions are met and the planning results are output.

[0174] As an example of the above steps, the present invention selects IEEE39 nodes as the research object for case analysis. To verify the effectiveness of the method proposed in the present invention, the following points are analyzed:

[0175] 1) Analysis of the rationality and effectiveness of configuration results;

[0176] 2) The impact of the frequency change rate indicator on the configuration results;

[0177] 3) The impact of the installed capacity ratio of hybrid storage and pure storage power stations on the configuration results.

[0178] 1. Analysis of the rationality and effectiveness of configuration results

[0179] 1) Configuration results and rationality analysis

[0180] The results of the coordinated configuration of the hybrid storage and pure storage power stations considering the inertia demand of the present invention are shown in Table 1. It is planned that the hybrid storage power station will add two units with a capacity of 249.04MW, the pure storage power station will add three units with a capacity of 272.22MW, and the reservoir capacity will be 10.516 million m 3 Without considering the inertia demand, the hybrid storage power station is planned to add 3 units with a capacity of 264.58MW, the pure storage power station is planned to add 1 unit with a capacity of 157.59MW, and the reservoir capacity is 2.0293 million m 3The average daily construction cost is 432,500 yuan. When inertia requirements are not considered, the system plans multiple hybrid storage units with lower unit construction costs. Because they are not affected by inertia constraints, the output of the thermal power units is lower, resulting in a 30.01% reduction in total system cost compared to when inertia requirements are considered.

[0181] Table 1 Configuration results

[0182]

[0183]

[0184] Depend on Figure 4 The data shows that the inertia provided by units other than pumped storage power stations is obviously insufficient, especially when photovoltaic power generation is large, the gap in system inertia is most serious, with the maximum reaching 5258MW·s and 5060MW·s respectively. The pumped storage units supplement the insufficient system inertia and absorb the power of new energy at the same time. During the flood season, the inertia demand of the system gradually increases, and the inertia of the units at all time points exceeds the minimum demand of the system, especially at 24:00, when the maximum inertia provided by all units is as high as 16626MW·s. Therefore, by planning pumped storage power stations, inertia support is effectively provided to the system to ensure that the initial frequency change rate of the system remains within a safe range when a disturbance occurs. Figure 5 As shown in (a), the minimum initial frequency change rate is 0.3932 Hz / s at 8:00 AM. During the dry season, the load is relatively stable throughout the day, so the minimum inertia required by the system varies little. Especially during periods of high wind power generation, the inertia provided far exceeds the system requirements, and the initial frequency change rate of the system at all times is above the minimum limit.

[0185] like Figure 6 It can be seen that when the inertia requirement is not considered, the system's initial frequency change rate remains within a reasonable range between 2:00 and 10:00. However, at other times, the initial frequency change rate exceeds 0.5 Hz / s, reaching a maximum of 0.8983 Hz / s at 22:00. As can be seen from the right figure, between 19:00 and 21:00, all units in the system are started, and the minimum initial frequency change rate at this time is 0.5703 Hz / s. Therefore, the configuration result without considering the inertia requirement cannot guarantee safe and reliable operation of the system.

[0186] In summary, the method of the present invention takes system inertia requirements into consideration when collaboratively planning hybrid storage and pure storage power stations, effectively enhancing the system's anti-interference capability.

[0187] 2) Validity Analysis of Configuration Results

[0188] As shown in Table 2, when the uncertainty of renewable energy sources is not considered, the system's construction and operating costs are reduced by 11.24% and 2.95%, respectively, compared to the scenario-based optimization approach. This cost difference stems primarily from the lack of scenario-based optimization. This eliminates the need for extensive flexible resources to accommodate diverse output scenarios, thereby reducing the required capacity of pumped-storage power plants and the associated investment costs. However, this configuration ignores the demand fluctuations brought about by scenario diversity. While this reduces initial investment, it may weaken the system's ability to adjust to diverse operating scenarios, impacting its overall stability and reliability.

[0189] Table 2 Configuration results without considering scenario optimization

[0190]

[0191] The analysis considers the operational status of the new energy uncertainty scenario, i.e., the configuration method of the present invention. The scenario method is used to generate multiple scenario data for the basic data. Due to space limitations, this section analyzes one scenario each during the dry season and the wet season, taking the data for scenario 1 during the wet season and scenario 6 during the dry season.

[0192] like Figure 7 As shown in the figure on the left, the initial frequency changes at each moment meet the minimum requirements of the system. The figure on the right shows the start and stop status of the pumped storage units. Units 1 and 2 are hybrid storage power station units, and units 3, 4, and 5 are pure storage power station units. At 12:00 and 23:00, 4 and 3 units were started respectively to ensure that the minimum inertia required by the system is provided. Therefore, even if the system inertia demand increases, there is still margin to start other pumped storage units to maintain safe operation. Similarly, Figure 8 During the afternoon and evening hours, when wind power is weak, system inertia is low and the frequency variation rate is high. However, during these periods, there are still pumped storage units that can be flexibly adjusted, effectively ensuring system operational safety. The frequency variation rate in other scenarios is similar, and the planning results effectively meet the operational requirements in each scenario.

[0193] like Figure 9 As shown in (a), in scenario 1, during the period from 2:00 to 7:00 when photovoltaic power generation is not in progress, the hydropower unit in the hybrid power station generates electricity. At this time, wind power surges at 2:00 and 7:00, but the pumped storage units of the hybrid power station cannot be started due to constraints, so the excess wind power is absorbed by the units of the pure storage power station. When the wind and solar power are strong from 10:00 to 17:00, the pure storage power station and the hybrid power station are both in the pumping state, which increases the space for new energy to be connected to the grid. Figure 9Figure (b) shows the operating power of the hydropower units and pumped-storage units in scenario 6. From 1:00 to 14:00, due to the high generation of renewable energy, the pumped-storage units of the hybrid and pure-storage power stations are activated to increase the amount of wind and solar power connected to the grid. From 15:00 to 17:00, wind power is low but photovoltaic power generation is still high. At this time, some hydropower units are activated to maintain system inertia, while the pumped-storage units of the hybrid power station cannot be started due to operating conditions. Therefore, the pure-storage power station units absorb the photovoltaic power.

[0194] In summary, joint planning of pure storage units can effectively cope with the complex operating conditions within the hybrid storage power station and enhance system flexibility.

[0195] 2. Impact of frequency change rate on configuration results

[0196] Depend on Figure 6 It can be seen that when the inertia requirement is not considered, the system specifications are only met at certain moments. Therefore, the frequency change rate indicator is the key factor affecting the configuration results. The impact of different frequency change rate indicators on the system configuration results is analyzed.

[0197] Table 3 shows that as the frequency change rate increases, the total system cost decreases significantly. When the frequency change rate increases from 0.5 Hz / s to 0.6 Hz / s, the total system cost decreases by 9.46%. When it increases to 0.8 Hz / s, the total cost drops further to 23.71%. Furthermore, the number of units built in pure-storage power plants decreases, while the number of units in hybrid-storage power plants increases. This is because the increased frequency change rate reduces the inertial kinetic energy required during system disturbances, eliminating the need for a large number of units to provide inertia. Since pure-storage power plants have higher unit construction costs, the number of units built in pure-storage power plants decreases, while the number of units built in hybrid-storage power plants increases to ensure economical system operation.

[0198] Table 3 Configuration results at different frequency change rates

[0199]

[0200] When the frequency change rate index increases to above 0.9 Hz / s, the system planning results remain unchanged, indicating that after RoCoF reaches a certain value, system operation and planning decisions are mainly affected by economic indicators. The system planning results are consistent with those when the system inertia requirement is not considered.

[0201] In summary, relaxing the system inertia requirement constraint gradually reduces the total system cost. Pumped storage units can leverage their flexible operation and fast response speed to support stable system operation. Properly planning pumped storage units can effectively provide the required inertial kinetic energy and ensure the system's economic efficiency.

[0202] 3. Impact of the installed capacity ratio of hybrid and pure storage power stations on configuration results

[0203] Analyze the configuration results of pure storage power stations and hybrid storage power stations under different ratios of installed capacity.

[0204] Table 4 Configuration results under different installed capacity ratios

[0205]

[0206] As shown in Table 4, when the ratio is between 4:6 and 2:8, the system's new energy is fully absorbed. When the ratio is 6:4, the planned number of hybrid storage power stations and the installed capacity have reached the upper limit, and three 299.07MW units are configured. Since hybrid storage is limited by the operating conditions between internal units and the upper limit of configuration, configuring a single hybrid storage power station cannot meet the system's operation and inertia requirements. Figure 10 When the ratio is 6:4, the total construction cost of the pumped storage power station is 871,300 yuan, while the total cost is 2,926,500 yuan. This is because the hybrid storage power station and the pure storage power station are restricted by their own internal constraints, resulting in a power abandonment penalty cost of 213,800 yuan, so the total cost is higher.

[0207] As the proportion of installed capacity of pure storage power stations increases, the total cost of the system first decreases, reaching the minimum value when the ratio is 4:6, and then the total cost gradually increases. The construction cost between the ratio of 5:5 and 2:8 gradually decreases, but the operating cost gradually increases. When the ratio is 1:9, since the pure storage power station plans 5 270MW units, the high investment and construction costs make its total cost higher than the case of configuring a pure storage power station alone. When a pure storage power station is configured alone, 4 256.53MW units are planned, with a total cost of 2.5359 million yuan, which is 6.05% higher than the total cost of the planning result of the method of the present invention. The result ratio configured by the present invention is 3.8:6.2. Therefore, when the installed capacity ratio of the mixed storage power station and the pure storage power station is between 4:6 and 3:7, the system economy is optimal.

[0208] Through the above design scheme, the present invention can bring the following beneficial effects:

[0209] 1. Considering the system's inertia requirements when configuring hybrid and pure storage power stations significantly improves the system's inertia level and enhances its regulatory flexibility. Failure to consider inertia requirements can make it impossible to guarantee safe system operation.

[0210] 2. After relaxing the system's frequency index, the number of pure storage power station units will decrease, the number of hybrid storage power station units will increase, and the total cost of the system will gradually decrease. When the frequency index is relaxed to a certain value, the system planning results will not be affected by the inertia demand.

[0211] 3. Through the joint planning of pure-storage and hybrid-storage power stations, the construction cost of pure-storage power stations can be effectively reduced and the complex operating conditions within hybrid-storage power stations can be effectively addressed.

[0212] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0213] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for capacity configuration of conventional hydropower station transformation combined with pure pumped storage power station, characterized in that: include: Obtaining basic parameters; the basic parameters include operating parameters of each unit and system; The basic parameters are input into the coordinated configuration model of pure-storage and hybrid-storage power stations, and the installed capacity and number of pumped-storage units added to the hydropower station, the installed capacity and number of units of the pure-storage power station, and the storage capacity of the upper reservoir are used as the planned quantities for configuration optimization to obtain a final planning scheme; the coordinated configuration model of pure-storage and hybrid-storage power stations is constructed based on the objective function, power station model, constraints, inertia requirements, and scenario method optimization; the power station model includes a pure pumped-storage power station model, a hybrid pumped-storage power station model, and the corresponding operating constraints of each model; The final planning scheme is determined as follows: The basic parameters of the planning year are obtained through operational simulation, and typical daily data for the flood and dry seasons are determined through cluster analysis. Under typical scenario data, the optimal configuration is performed considering the uncertainty of wind and solar power output. The preliminary planning results of the pumped storage units are first obtained, and then the preliminary planning results are judged. If the set scenario data is met, the preliminary planning results are output as the final planning scheme. If the set scenario data is not met, the unsatisfactory data is added to the scenario data of the previous moment for re-planning until the final planning scheme is output; The objective function aims to minimize the total cost, which includes the life cycle cost of the pumped storage power station and the system operation cost: Where, F op is the average system operating cost on typical days in the flood season and dry season, F inv The full life cycle cost of the pumped storage unit; Where, F ci 、F cm and F cd are the annual investment cost, maintenance cost and replacement cost of the pumped storage power station respectively; when s is 1, it is the flood season, and when s is 2, it is the dry season; C s,h 、C s,hy 、C s,pump 、C s,cur and C s,x They are thermal power operation cost, hydropower operation cost, pumped storage operation cost, renewable energy curtailment cost and spinning reserve cost; the variables in the formula are for a single scenario; Where, P 1,i,max 、P 2,i,max They are the installed capacity of a single unit of the planned hybrid storage and pure storage power stations respectively; is the planned capacity of the reservoir of the pure storage power station; ρ1 and ρ2 are the unit installed capacity investment costs, ρ3 is the unit capacity investment cost of the reservoir of the pure storage power station, α m is the annual maintenance rate; γ is the discount rate; Y is the life cycle of the pumped storage power station; α d is the replacement rate; N1 and N2 are the planned numbers of pumped storage units in hybrid storage and pure storage power stations respectively.

2. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 1 is characterized in that: The pure storage power station output model of the pure pumped storage power station model is: Where, and They are the storage and release water volumes of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power output of the i-th pumped storage unit at time t; η c and η d are the pumping efficiency and power generation efficiency of the pumped storage unit; ρ is the water density; g is the acceleration of gravity; h is the average head; N2 is the planned number of pumped storage units in the pure storage power station.

3. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 2 is characterized in that: The operation constraints corresponding to the pure storage power station output model include output limit constraints, first storage capacity constraints and spinning reserve constraints.

4. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 1 is characterized in that: The conventional hydropower unit output model of the hybrid pumped storage power station model is: Where: is the power generated by the i-th hydropower unit at time t; is the power generation flow of the hydropower unit; H i,t is the generating head of the hydropower unit; η is the generating efficiency.

5. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 4 is characterized in that: The operating constraints corresponding to the conventional hydropower unit output model include upper and lower reservoir constraints, second storage capacity constraints, water level fluctuation constraints and hydropower unit constraints; wherein, the hydropower unit constraints include output constraints, vibration zone constraints, generating head constraints, climbing constraints and output operating condition constraints between pumped storage power station units.

6. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 1 is characterized in that: The constraints include power balance constraints, line transmission capacity constraints and quasi-steady-state frequency constraints.

7. The capacity configuration method for conventional hydropower station transformation combined with pure pumped storage power station according to claim 1 is characterized in that: The typical scene data is generated using the scene method. The data generated and reduced by the scene method is: Where: P new,α 、P L,α is the new energy power and load value under the αth scenario; P newpre 、P Lpre is the power prediction value under the basic scenario; is the power prediction error value under the αth scenario.

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