Capacity configuration method for transforming conventional hydropower station and combining pure pumped storage power station

Abstract

The invention discloses a capacity configuration method for transforming a conventional hydropower station and combining a pure pumped storage power station, and relates to the technical field of power systems. The method comprises the following steps: acquiring basic parameters; the basic parameters comprise operation parameters of each unit and a system; inputting the basic parameters into a pure storage and mixed storage power station cooperative configuration model, and performing configuration optimization by taking the installed capacity and the number of pumping storage units additionally arranged in a hydropower station, the installed capacity and the number of units of a pure storage power station and the capacity of an upper reservoir as to-be-planned quantities to obtain a final planning scheme; the pure storage power station and mixed storage power station cooperative configuration model is optimized and constructed based on an objective function, a power station model, constraint conditions, inertia requirements and a scene method; the power station model comprises a pure pumped storage power station model, a hybrid pumped storage power station model and operation constraints corresponding to the models. According to the invention, the configured capacity can be ensured to meet the flexibility and safety requirements of the system under different conditions.

Description

Technical Field

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

[0002] The grid connection of new energy has the problem of output uncertainty and the inability to provide inertia support when the system is disturbed, which limits its development. Therefore, it is urgent to flexibly adjust resources to cooperate with the output of new energy. Hydropower is an important resource to ensure the safe and stable operation of the power system and the consumption of new energy, but limited development resources restrict the planning and construction of hydropower. Therefore, it is crucial to reasonably transform conventional hydropower and give full play to the advantages of "equal emphasis on power supply and flexible regulation" to promote the development of new energy and hydropower industries.

[0003] China encourages the transformation of conventional hydropower stations and the scientific development of pumped storage power stations. As a green regulating power source with mature technology and large-scale development, pumped storage power stations play a key role in promoting new energy to become the main force of electricity and ensuring the stable development of the power system. Therefore, reasonable planning of the capacity of pumped storage power stations is of great significance to ensure their efficient operation and improve the flexibility of the system.

[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] At present, the research on hybrid storage power stations mainly focuses on the direct transformation of existing hydropower stations and the analysis of their advantages in dispatching, but there is a lack of research on the impact of the scale of transformation on the system. Secondly, due to the limited scale of transformation of conventional hydropower stations, only considering the planning of hybrid storage power stations may not meet the system needs. Considering the joint planning of hybrid storage and pure storage power stations, the impact of the capacity of the two configurations on the system operation needs to be studied urgently. In addition, the current rationality of pumped storage planning is mainly analyzed from an economic perspective, while ignoring its ability to provide inertia support to the system to 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 transformation 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 quantities to be planned 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 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 operating constraints corresponding to each model.

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

[0012] The basic parameters of the planning year are obtained by operation simulation, and the typical daily data of the flood season and the dry season are determined by 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, and the total cost includes the full life cycle cost of the pumped storage power station and the system operation cost:

[0014]

[0015] In the formula, F op is the average system operation 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] In the formula, and They are the water storage and release of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power generated by the i-th pumped storage unit at time t; η c and η d is 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 water head; N 2 Planned number of pumped storage units in pure storage power stations.

[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 generation of the i-th hydropower unit at time t; H is the power generation flow of the hydropower unit; 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, a second storage capacity constraint, a water level variation constraint and a hydropower unit constraint; wherein the hydropower unit constraints include output constraints, vibration zone constraints, generating head constraints, climbing constraints and output operating condition constraints between units of the pumped storage power station.

[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 by using a scene method, and the data generated and reduced by 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 capacity configuration method for a conventional hydropower station transformation combined with a pure pumped-storage power station, the method comprising obtaining basic parameters; the basic parameters comprising operating parameters of each unit and system; inputting the basic parameters into a pure storage and hybrid storage power station coordinated configuration model, and taking 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 the quantities to be planned for configuration optimization, and obtaining a final planning scheme; the pure storage and hybrid storage power station coordinated configuration model is constructed based on objective function, power station model, constraint conditions, inertia demand and scenario method optimization; the power station model comprises 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 demand after system disturbance, 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 conditions. 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

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

[0032] Figure 2 This is a schematic diagram of peak load regulation and inertia support of a pumped storage power station in this embodiment;

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

[0034] Figure 4 Schematic diagram of the system inertia during the flood season and the dry season in this embodiment; wherein, part (a) is a schematic diagram of the flood 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 the dry season considering the 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 the start-stop state of the unit during the flood season when the inertia demand is not considered in 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;

[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] Fig. 9 Schematic diagram of the operating power of the hydropower unit and the pumped storage unit in scenario 1 and scenario 6 of this embodiment; wherein, part (a) is a schematic diagram of scenario 1; part (b) is a schematic diagram of scenario 6;

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

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 transformation 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 pure pumped-storage power station. While coping with the complex working conditions of the hybrid power station and reducing the construction cost of the pure power station, the system inertia demand is taken into account to ensure its economic and safe operation. First, the planning year data is obtained by operation simulation, and the minimum system inertia that meets the frequency safety constraint 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 integrated, 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 operation requirements under different circumstances. Finally, the example 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 system flexibility, while ensuring that the frequency index of the system is within a reasonable range after the disturbance.

[0045] The present invention provides a method for configuring the capacity of a conventional hydropower station 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 quantities to be planned 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 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 operating constraints corresponding to each model.

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

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

[0050] 1. System inertia requirement analysis

[0051] When the system is disturbed, the inertia response process is used to maintain stability. Even if new energy generation can provide virtual inertia through control means, the uncertainty of new energy output will cause difficulty in system regulation or insufficient inertia. Therefore, pumped storage power stations are planned to provide the system with the inertial kinetic energy required for anti-disturbance. Factors that affect the size of the system's required inertia 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] In the formula, f 0 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 generation needs to cooperate with energy storage power stations to participate in frequency regulation, the new energy of the present invention only considers the virtual inertia provided by wind power generation, and uses an equivalent model to calculate its virtual inertia time constant. The formula is as follows:

[0055]

[0056] In the formula, 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 fan; 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 inertia support of the system 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, and the formula is as follows:

[0058]

[0059] In the formula, 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, and a balance point must be found to take 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] When a disturbance occurs suddenly in the system, unbalanced power will be generated, causing the system frequency to change. The instantaneous frequency change of the system disturbance is 0, and the frequency change rate reaches the maximum value at this time. In order to prevent the frequency change rate after the disturbance from exceeding the specified value and causing system safety problems, the units in the system need to provide sufficient inertia. The frequency change rate formula is as follows, and its size is inversely proportional to the inertia of the system.

[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 climbing models, dynamic response models and response time models. The model used in the present invention depends on the system inertia, the unit climbing 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 reserve units.

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

[0068] Conventional hydropower stations are transformed into hybrid power stations by adding pumped storage units, realizing the functional transformation from one-way power generation to two-way regulation. Hybrid power stations make full use of water resources to improve the flexibility and economy of system operation, but after the transformation, the operating conditions and water conditions between the units are more complicated, with complex nonlinear characteristics inside, and affected by the scale of the hydropower station, the installed capacity of the pumped storage units that can be added is limited. Therefore, it is considered to plan a pure storage power station at the same time, and the two together provide flexible adjustment capabilities and inertia support for the system.

[0069] Depend on Figure 2 It can be seen that during load peak, 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 to alleviate the peak-shaving pressure and provide inertia support for the system; during load valley, the hybrid and pure storage are in pumping conditions, and the hybrid storage power station is affected by internal operating constraints. Only the hydropower units that undertake daily power generation tasks are in the start-up state, and the other hydropower units cannot be started. Therefore, only some units of 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, through coordinated planning of hybrid storage power stations and pure storage power stations, the construction scale limitations of hybrid storage power stations themselves can be solved and the impact of complex internal working conditions can be eliminated. At the same time, the high construction cost of pure storage power stations can be reduced, and sufficient inertial response can be provided in the event of sudden disturbances in the system, thereby enhancing the system's anti-disturbance capability and ensuring 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 mixed storage power stations is established. 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 the quantities to be planned. To simplify the calculation, the data during the flood season and the dry season in the annual data are clustered to form typical daily data, and the appropriate installed capacity of the pumped storage power station is configured through the typical daily data. However, the planning results obtained only through typical days may not meet the different operating conditions of the system. Therefore, in order to make the final planning results universal, the preliminary planning results are subsequently optimized through the scenario analysis method to ensure that the planned pumped storage power station can effectively cope with the uncertainty of new 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] In the formula, F op is the average system operation 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] In the formula, 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 They are respectively the operating costs of thermal power, hydropower, pumped storage, the cost of abandoned power from new energy sources and the cost of spinning reserve. The variables in the formula are in 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; The planned capacity of the reservoir for a pure storage power station; ρ 1 and ρ 2 is the unit installed capacity investment cost, ρ 3 is the unit capacity investment cost of the reservoir in the pure storage power station α mis 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; N 1 and N 2 The planned number of pumped storage units for hybrid storage and pure storage power stations are respectively.

[0081]

[0082] In the formula, λ 1,i and λ 2,i 0-1 variables indicating whether unit i is put into construction, 1 indicates construction, 0 indicates no construction; P 1 and P 2 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 capacity of a single hybrid 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 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] In the formula, 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 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] In the formula, C hy The operating cost of the hydropower unit; is the start-up and shutdown cost of the hydropower unit; hy is the hydropower operation and maintenance cost coefficient.

[0090]

[0091] In the formula, C pump is the operating cost of the pumped storage unit; is the start-stop cost of pumped storage. Since the pumped storage power station recovers the variable cost of peak load regulation through the electricity price, the profit coefficient α is considered 1 and α 2 Quantify the operating benefits of pumped storage power stations; 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] In the formula, C cur is the penalty cost for power abandonment; ξ is the penalty cost for unit power abandonment; and Forecast power for wind and solar; and It is the actual grid power of wind and solar power.

[0094]

[0095] In the formula, C x is the spinning reserve cost; μ 1 and μ 2 are the spinning reserve cost coefficients for conventional units and pumped storage units respectively; They provide rotating reserve capacity for thermal power, hydropower, pumped storage units in pure storage power stations and pumped storage units in 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 water storage and release of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power generated by the i-th pumped storage unit at time t; η c and η d is 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 water head; N 2 Planned number of pumped storage units in pure storage power stations.

[0100] Operation constraints of pure storage power station:

[0101] Generally, the water volume of the lower reservoir of a pumped storage power station is sufficient, and only the capacity of the upper reservoir is considered. The operating constraints of the pumped storage units in a mixed storage power station are the same as below.

[0102] 1) Output Limitation 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 full power generation of the pure storage power station for 6 hours.

[0108] 3) Spinning reserve constraints

[0109]

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

[0111]

[0112] In the formula, It is the pumping and discharge volume of the rotating reserve of the pumped storage power station. It indicates the reservoir capacity required for the rotating 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 generation of the i-th hydropower unit at time t; H is the power generation flow of the hydropower unit; 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] In the formula, 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] In the formula, 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 range of variation of the initial and final capacity of the reservoir.

[0129] Hydropower unit constraints

[0130] 1) Output constraints

[0131]

[0132] In the formula, and It is the lower and upper limits of the power generation of the hydropower unit; and It is the lower and upper limits of the power generation flow of the hydropower unit; It is the start and stop variable of the hydropower unit.

[0133] 2) Vibration zone constraints

[0134]

[0135] In the formula, 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 constraints

[0137]

[0138] In the formula, is the head loss.

[0139] 4) Climbing constraints

[0140]

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

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

[0143]

[0144] In the formula, They are the start and stop of the hydropower unit in the hybrid storage power station and the pumping and power generation status of the pumped storage unit. This formula indicates that the pumping and power generation status 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] In the formula, is the system load; and They are the pumping power of mixed storage and pure storage power stations respectively; and They are the power generation capacities of hybrid storage and pure storage power stations respectively.

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

[0152]

[0153] In the formula, 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; θ 0 is the equilibrium node phase angle value.

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

[0155]

[0156] In the formula, 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] In the formula, and are the upper and lower limits of the operating area of ​​the hydropower unit; k is the number of operating areas of the hydropower unit, that is, the number of areas outside the vibration area; y i,t,j 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 is 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] The uncertainty of wind and solar power output is quantified by using scenario analysis. Since there are certain errors in the predicted values, 1000 sets of data are generated by using Latin hypercube sampling for the prediction error, and the 1000 sets of data are reduced to 5 scenarios by using the fast previous generation elimination technology based on probability distance. The data after scenario generation and reduction are 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 , P Lpre 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 Error 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 The planned annual wind and solar load data are obtained by running simulations, and typical daily data of the flood season and the dry season are obtained by clustering methods. The preliminary planning values ​​of the pumped storage units are obtained under typical scenarios, and then it is judged whether the obtained planning values ​​can meet the operating constraints of other scenarios. If they do, the planning values ​​are output; otherwise, the unsatisfactory scenario data are added to the basic scenario to re-plan the results, and the iterations are continued until the judgment conditions are met and the planning results are output.

[0174] As an embodiment 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 by 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 The average daily construction cost is 924,900 yuan. Without considering the inertia demand, the hybrid power station is planned to add 3 units with a capacity of 264.58MW, the pure power station is planned to add 1 unit with a capacity of 157.59MW, and the reservoir capacity is 2.0293 million m 3 The average daily construction cost is 432,500 yuan. When the inertia demand is not considered, the system plans multiple hybrid storage units with lower unit construction costs, and because they are not affected by the inertia constraint, the output of the thermal power units is relatively small, which reduces the total system cost by 30.01% compared with the case of considering the inertia demand.

[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 high, the gap in system inertia is most serious, reaching a maximum of 5258MW·s and 5060MW·s respectively. The pumped-storage units supplement the insufficient system inertia and absorb the power of new energy. 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 to effectively provide inertia support for the system, it is ensured that the initial frequency change rate of the system remains within a safe range when disturbances occur. Figure 5 From (a), we can see that the minimum initial frequency change rate is 0.3932 Hz / s at 8:00. During the dry season, the load is relatively stable throughout the day, so the minimum inertia required by the system changes little, especially when the wind power generation is large, the inertia provided far exceeds the system demand, and the initial frequency change rate of the system at each moment is higher than the minimum limit.

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

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

[0187] 2) Validity analysis of configuration results

[0188] As shown in Table 2, when the uncertainty of new energy is not considered, the construction cost and operating cost of the system are reduced by 11.24% and 2.95% respectively compared with the scenario optimization method. This cost difference mainly comes from the fact that the scenario optimization configuration is not adopted. The system does not need to be equipped with a large amount of flexible resources to cope with different output scenarios, thereby reducing the installed capacity demand and related investment costs of pumped storage power stations. However, this configuration ignores the changes in demand brought about by the diversity of scenarios. Although it reduces the initial investment, it may weaken the system's ability to adjust in diversified operating scenarios and affect its overall stability and reliability.

[0189] Table 2 Configuration results without considering scenario optimization

[0190]

[0191] The operation of the scenario considering the uncertainty of new energy is analyzed, that is, the configuration method of the present invention. The scenario method is used to generate multiple scenario data for the basic data. Due to the limited space, this section analyzes one of the scenarios in the dry season and the wet season respectively, taking the scenario 1 data in the wet season and the scenario 6 data in 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 system requirements. 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 room to start other pumped storage units to maintain safe operation. Similarly, Figure 8 In the afternoon and evening when wind power is weak, the system inertia is small and the frequency change rate is large, but there are still flexible pumped storage units remaining during this period, which effectively ensures the safety of system operation. The frequency change rate in other scenarios is similar, and the planning results effectively meet the operation requirements in each scenario.

[0193] like Fig. 9As 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 units in the hybrid power station generate electricity. At this time, wind power surges at 2:00 and 7:00, but the pumped storage units in 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 a pumping state, increasing the space for new energy to be connected to the grid. Fig. 9 (b) shows the operating power of the hydropower units and pumped storage units under scenario 6. From 1:00 to 14:00, due to the large generation of renewable energy, the pumped storage units of the hybrid and pure storage power stations are started to increase the amount of wind and solar power connected to the grid. From 15:00 to 17:00, the wind power is low but the photovoltaic power generation is still high. At this time, some hydropower units are started to maintain the system inertia, while the pumped storage units of the hybrid power station cannot be started due to operating conditions. Therefore, the photovoltaic power is absorbed by the pure storage power station units.

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

[0195] 2. The 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 specified indicators are only met at certain moments. Therefore, the frequency change rate indicator is the key factor affecting the configuration result. The influence of different frequency change rate indicators on the system configuration results is analyzed.

[0197] It can be seen from Table 3 that as the frequency change rate index increases, the total system cost decreases significantly. When the frequency change rate increases from 0.5Hz / s to 0.6Hz / s, the total system cost decreases by 9.46%, and when it increases to 0.8Hz / s, the total cost further decreases to 23.71%. In addition, the number of units built in pure storage power stations gradually decreases, while the number of units built in hybrid storage power stations increases. This is because as the frequency change rate increases, the inertial kinetic energy required when the system is disturbed gradually decreases, so that the system does not need a large number of units to provide inertia, and the unit construction cost of pure storage power stations is large, so the number of units built in pure storage power stations is reduced, and in order to ensure the economy of system operation, the number of units built in hybrid storage power stations is increased.

[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 result remains unchanged, indicating that after RoCoF reaches a certain value, the system operation and planning decisions are mainly affected by economic indicators, and the system planning results are consistent with the results when the system inertia demand is not considered.

[0201] In summary, after relaxing the system inertia demand constraint, the total cost of the system gradually decreases. Pumped storage units can use the advantages of flexible operation and fast response speed to support the stable operation of the system. Planning appropriate pumped storage units can effectively provide the inertial kinetic energy required by the system and ensure the economy of the system.

[0202] 3. Impact of installed capacity ratio of hybrid storage 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 and installed capacity of the hybrid storage power station 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, a single hybrid storage power station cannot meet the system's operation and inertia requirements. Fig.10 When the ratio is 6:4, the total construction cost of the pumped storage power station is 871,300 yuan, and 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 penalty cost of power abandonment of 213,800 yuan, so the total cost is relatively high.

[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, due to the planning of 5 270MW units for the pure storage power station, the high investment and construction costs make its total cost higher than the case of configuring a pure storage power station alone. When the 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 hybrid 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. Consider the inertia requirements of the system when configuring hybrid and pure storage power stations, significantly improve the inertia level of the system, and enhance its adjustment flexibility. If the inertia requirements are not considered, the safe operation of the system cannot be guaranteed.

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

[0211] 3. Through 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 dealt with.

[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 article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood 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 quantities to be planned 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 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 operating constraints corresponding to each model.

2. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 1 is characterized in that: The final planning scheme is determined by: The basic parameters of the planning year are obtained by operation simulation, and the typical daily data of the flood season and the dry season are determined by 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.

3. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 1 is characterized in that: 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: In the formula, F op is the average system operation cost on typical days in the flood season and dry season, F inv The full life cycle cost of the pumped storage unit.

4. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 1 is characterized in that: The pure storage power station output model of the pure pumped storage power station model is: In the formula, and They are the water storage and release of the pure storage power station, is the pumping power of the i-th pumped storage unit at time t, is the power generated by 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 water head; N2 is the planned number of pumped-storage units in the pure storage power station.

5. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 4 is characterized in that: The operation constraints corresponding to the output model of the pure storage power station include output limit constraints, first storage capacity constraints and spinning reserve constraints.

6. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method 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 generation of the i-th hydropower unit at time t; H is the power generation flow of the hydropower unit; i,t is the generating head of the hydropower unit; η is the generating efficiency.

7. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 6 is characterized in that: The operating constraints corresponding to the conventional hydropower unit output model include upper and lower reservoir constraints, second reservoir 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.

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

9. The conventional hydropower station transformation combined with pure pumped storage power station capacity configuration method according to claim 2 is characterized in that: The typical scene data is generated by 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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