Pumped storage multi-year capacity optimization method and system considering wind and light continuous low output

Abstract

The invention discloses a pumped storage multi-year capacity optimization method and system considering wind and light continuous low output. The method comprises the steps of constructing a target function comprehensively considering economical efficiency and new energy consumption requirements, and constructing pumped storage construction constraints, typical scene constraints and extreme scene constraints; a pumped storage multi-year capacity optimization model considering wind and light continuous low output is composed of an objective function, pumped storage construction constraints, typical scene constraints and extreme scene constraints, a typical week scene and an extreme week scene are used as input, a solver is used for optimization solution, and finally an optimal configuration scheme of pumped storage capacity is obtained. The system comprises an objective function construction module, a constraint construction module and a model construction and solving module. According to the invention, the potential extreme supply protection problem of the power system is solved.

Description

Technical Field

[0001] The present invention belongs to the field of power system operation planning, and specifically relates to a method and system for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power. Background Art

[0002] With the rapid progress of new energy generation technologies such as wind power and photovoltaic power, a high proportion of new energy access to the power grid has become an important feature of the new power system. However, due to the greater randomness and volatility of new energy generation, the future power system will face a series of severe challenges in planning and operation, including the increasing difficulty of ensuring the safe supply of electricity, the continued pressure of new energy consumption, and the increasingly prominent problems of system safety and stability. Therefore, flexible adjustment resources that can ensure power supply, support new energy consumption, and enhance system stability are extremely critical to the construction of new power systems.

[0003] Pumped storage is currently the most mature, most economically efficient, and most suitable regulating power source for large-scale development.

[0004] Traditional pumped storage capacity optimization methods are usually based on wind and solar output characteristics and load characteristics. They are optimized by constructing typical scenarios, focusing on the power balance on a short-term daily time scale, and providing capacity planning solutions that meet the system's economic and reliability requirements. However, with the frequent occurrence of extreme weather events, new power systems with a high proportion of renewable energy are facing severe power balance risks. In the scenario of no wind or no light for many consecutive days, due to the significant decline in wind and solar output, the power system will face the dilemma of insufficient power supply during multiple consecutive peak load periods. The load supply situation is extremely severe, and even large-scale load shedding events may occur, which will lead to serious social and economic losses and endanger the overall safety of the power system. The existing pumped storage capacity optimization methods have not fully considered the medium- and long-term power imbalance risks brought about by the extreme continuous low output of renewable energy and its impact on the optimal configuration plan of pumped storage capacity.

[0005] In summary, it is urgent to identify and extract extreme scenarios based on the extreme low output fluctuation conditions and output levels of new energy, consider extreme scenario constraints including load shedding constraints, and take into account the supply guarantee needs of extreme scenarios on the basis of taking into account the economy and reasonable absorption requirements of typical scenarios. A pumped storage capacity optimization model considering extreme continuous low output of wind and solar power is constructed, and in-depth research is conducted on how to improve the system's flexible adjustment capability and power supply reliability under extreme conditions by optimizing pumped storage capacity, and analyze the mechanism of peak supply guarantee of pumped storage in the continuous low output scenario of new energy. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the existing pumped storage capacity optimization method, consider the supply guarantee requirements of continuous low output of wind and solar power in extreme scenarios, and propose a pumped storage multi-year capacity optimization method and system considering continuous low output of wind and solar power. By constructing extreme scenario constraints to avoid large-scale load shedding in extreme situations, the pumped storage capacity optimization method comprehensively describes the fluctuation characteristics of extreme continuous low output of wind and solar power through identification and extraction of extreme continuous low output scenarios of wind and solar power, and explore how to optimize the pumped storage capacity configuration to improve the supply guarantee pressure in extreme scenarios, so as to promote the solution of potential extreme supply guarantee problems of power systems.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The multi-year capacity optimization method of pumped storage considering the continuous low output of wind and solar power includes the following steps:

[0009] Step 1: Construct an objective function that comprehensively considers economic efficiency and new energy consumption needs;

[0010] Step 2: Combine the construction scale limit and the unit operation relationship, constrain the investment decision to ensure the feasibility of the plan, and construct the pumped storage construction constraints;

[0011] Step 3: Consider various power sources and pumped storage operations, spare capacity, upper and lower limits of transmission lines, and power balance conditions to construct typical scenario constraints;

[0012] Step 4: Identify and extract low-output scenarios based on historical data, moderately relax load shedding restrictions, and build extreme scenario constraints for safety verification;

[0013] Step 5: A multi-year capacity optimization model for pumped storage considering continuous low output of wind and solar power is constructed, which is composed of objective function, pumped storage construction constraints, typical scenario constraints and extreme scenario constraints. The typical weekly scenario and extreme weekly scenario are used as input, and the solver is used for optimization and solution, and finally the optimal configuration plan of pumped storage capacity is obtained.

[0014] A further improvement of the present invention is that, in step 1, an objective function that comprehensively considers economic efficiency and new energy consumption demand is constructed, including:

[0015] The goal is to minimize the overall system cost. The objective function includes: investment depreciation, coal consumption, start-up and shutdown, power abandonment and load shedding costs, and the weighted sum is calculated according to the weight of typical scenarios to convert them into equal annual values.

[0016] The specific mathematical expression of the objective function is as follows:

[0017]

[0018] Where: k refers to the typical scenario number; h refers to the year number; t refers to the time number; w refers to the new energy base number; n refers to the load node number; g refers to the thermal power unit number; N K is the total number of typical scenes; N H is the capacity planning period; T is the total duration of the calculation cycle, which is 168; N W is the total number of new energy bases; N N is the total number of load nodes; N G is the number of thermal power units; P k is the sampling probability of each typical scene; q h K is the conversion factor of weekly operating expenses to annual operating expenses; w K is the penalty coefficient for abandonment of renewable energy; n is the load shedding penalty coefficient; The new energy output of the system at time t is predicted, is the new energy output actually consumed by the system at time t; is the load shedding amount of each load node; C g,Ge is the slope of the approximated coal consumption function; C g,min The coal consumption cost of each thermal power unit with the minimum technical output; is the actual output of each thermal power unit, P g,min is the minimum technical output of each thermal power unit; S gz is the shutdown cost coefficient of thermal power units; S gy is the startup cost coefficient of thermal power units; It is the 0-1 state variable of the thermal power unit; It is the 0-1 shutdown action variable of the thermal power unit; is the thermal power unit 0-1 startup action variable; r h is the discount factor for year h; The investment cost of the pumped storage unit;

[0019]

[0020]

[0021] Where: ps refers to the number of the pumped storage power station; c refers to the number of the constant speed and constant frequency pumped storage unit in the pumped storage power station ps; v refers to the number of the variable speed and constant frequency pumped storage unit in the pumped storage power station ps; N PS is the number of pumped storage power stations; C c,h , C v,h Y is the investment depreciation coefficient of each pumped storage unit; c,h , Y v,h is the construction state variable of each pumped storage unit; r m,c / v is the equal annual value coefficient of the c / v of the pumped storage unit, i is the discount rate, which is 6%, and m is the operating life of the c / v of the pumped storage unit.

[0022] A further improvement of the present invention is that, in step 2, combined with the construction scale limitation and the unit operation relationship, the investment decision is constrained to ensure the feasibility of the plan, and the pumped storage construction constraints are constructed, including: annual maximum investment constraints, single power station maximum investment constraints, power station investment sequence constraints, power station unit investment sequence constraints, investment and construction and unit output relationship constraints, investment and construction action and status relationship constraints.

[0023] A further improvement of the present invention is that, in step three, various power sources and pumped storage operation, spare capacity, upper and lower limits of transmission lines and power balance conditions are comprehensively considered to construct typical scenario constraints, including: thermal power unit status constraints, thermal power unit operation constraints, unit minimum continuous start-up and shutdown time constraints, thermal power unit spare constraints, pumped storage unit constraints, new energy power operation constraints, load shedding constraints, power balance constraints, flow safety constraints and total spare constraints.

[0024] A further improvement of the present invention is that the pumped storage unit constraint models the constant speed and constant frequency unit and the variable speed and constant frequency unit respectively;

[0025] The constant speed and frequency pumped storage unit is modeled as follows:

[0026]

[0027]

[0028]

[0029] Where: Indicates the actual power generation output of constant speed pumped storage unit c; Indicates the upward reserve of constant speed pumped storage unit c; Indicates the maximum and minimum power output of the constant speed pumped storage unit c; represents the power generation state variable of the constant speed pumped storage unit c; Indicates the downward reserve of constant speed pumped storage unit c; represents the actual pumping power of the constant speed pumped storage unit c;

[0030] represents the constant speed pumping power of the constant speed pumped storage unit c; represents the pumping state variable of the constant speed pumped storage unit c;

[0031] At the same time, the variable speed constant frequency pumped storage unit is modeled, namely:

[0032]

[0033]

[0034]

[0035]

[0036] Where: Indicates the actual power generation output of variable speed pumped storage unit v; represents the actual pumping power of variable speed pumped storage unit v; represents the power generation state variable of the variable speed pumped storage unit v; represents the pumping state variable of the variable speed pumped storage unit v; Indicates the maximum and minimum power generation output of variable speed pumped storage unit v; Indicates the maximum and minimum pumping power of variable speed pumped storage unit v; Indicates the upward reserve of variable speed pumped storage unit v; Indicates the downward reserve of variable speed pumped storage unit v;

[0037] Pumped storage cannot be in power generation and pumping state at the same time.

[0038]

[0039] In addition, it is necessary to construct a storage capacity balance constraint:

[0040]

[0041]

[0042]

[0043]

[0044] Where: Represents the real-time storage capacity of the pumped storage power station ps; represents the initial storage capacity of the pumped storage power station ps; represents the storage capacity of the pumped storage power station ps at time T; η p and η g denote the pumping and power generation efficiencies, respectively; and They represent the maximum storage capacity and minimum storage capacity of the pumped storage power station ps respectively.

[0045] A further improvement of the present invention is that in the new energy power operation constraint, the new energy output is less than the total resource volume, and the new energy consumption rate restriction is considered:

[0046] First, the power generation needs to meet the constraint of being less than the resource amount;

[0047]

[0048] Where: represents the actual wind and solar power of new energy base w at time t under typical scenario k; represents the predicted wind and solar power of new energy base w at time t under typical scenario k;

[0049] At the same time, it is necessary to ensure that the output of new energy is within a reasonable consumption range;

[0050]

[0051] In the formula: μ represents the reasonable consumption rate of new energy, which is taken as 95%.

[0052] A further improvement of the present invention is that, in the load shedding constraint, the total load shedding amount in a single scenario is less than a certain threshold:

[0053]

[0054] Where: It represents the upper limit of the total load shedding under the typical scenario k.

[0055] A further improvement of the present invention is that the total reserve constraint takes into account the reserve capacity demand due to the load forecast error and the new energy forecast error;

[0056]

[0057]

[0058] Where: ω is the spinning reserve rate, which is 5%; is the maximum load of the system under typical scenario k; ω w It represents the coefficient of the spinning reserve capacity increased to cope with the random fluctuation of renewable energy, which is taken as 25%.

[0059] A further improvement of the present invention is that, in step 4, the extreme scenario constraint further relaxes the load shedding limit on the basis of the typical scenario constraint, and at the same time, the extreme scenario variable is not included in the objective function, but only included in the constraint for extreme supply security inspection;

[0060] Replace the variables in various power sources and pumped storage constraints with variables in extreme scenarios, introduce extreme scenario constraints, and for storage capacity balance constraints (12)-(15):

[0061]

[0062]

[0063]

[0064]

[0065] And so on, the remaining typical scenario constraints are rewritten.

[0066] The multi-year capacity optimization system of pumped storage considering the continuous low output of wind and solar power includes:

[0067] Objective function construction module, which constructs an objective function that comprehensively considers economic efficiency and new energy consumption needs;

[0068] The first constraint construction module combines the construction scale limit and the unit operation relationship to constrain investment decisions to ensure the feasibility of the plan and construct pumped storage construction constraints;

[0069] The second constraint building module builds typical scenario constraints by comprehensively considering various power sources and pumped storage operations, spare capacity, upper and lower limits of transmission lines, and power balance conditions;

[0070] The third constraint construction module identifies and extracts low-output scenarios based on historical data, moderately relaxes load shedding restrictions, and constructs extreme scenario constraints for safety verification;

[0071] The model construction and solution module is composed of objective function, pumped storage construction constraints, typical scenario constraints and extreme scenario constraints. It takes the typical weekly scenario and extreme weekly scenario as input, uses the solver to perform optimization and solution, and finally obtains the optimal configuration plan of pumped storage capacity.

[0072] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0073] The present invention focuses on the power supply guarantee needs of renewable energy power generation in extremely low-output scenarios. Based on the requirements of power system safety and reliability, it considers the system load shedding limitations and constructs extreme scenario constraints. In the optimization model, it takes into account the economic goals in typical scenarios, the demand for renewable energy consumption and the safety verification in extreme situations.

[0074] Compared with existing methods, this model meticulously depicts the fluctuation characteristics of wind power and photovoltaic power generation under extreme continuous low output conditions, and incorporates extreme scenario constraints into the multi-year capacity optimization configuration model of pumped storage, effectively reflecting the weekly time scale regulation capability of pumped storage in response to continuous low output conditions. Specifically, this model takes into account the power supply constraints during extremely low output periods, and significantly reduces the system's load shedding risk in extreme scenarios by configuring more pumped storage units, improving the reliability and safety of power supply, thereby demonstrating its significant advantages in responding to extreme weather. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 It is the overall flow chart of the present invention.

[0076] Figure 2 is the load curve of the example system, where Figure 2 (a) is a typical scenario 1. Figure 2 (b) is typical scenario 2. Figure 2 (c) is typical scenario 3. Figure 2 For (d) typical scenario 4, Figure 2 (e) is extreme scenario 1, Figure 2 (f) is extreme scenario 2.

[0077] Figure 3 is the wind and solar resource curve of the example system, where Figure 3 (a) is a typical scenario 1. Figure 3 (b) is typical scenario 2. Figure 3 (c) is typical scenario 3. Figure 3 (d) is typical scenario 4. Figure 3 (e) is extreme scenario 1, Figure 3 (f) is extreme scenario 2.

[0078] Figure 4 is the output accumulation curve of each unit in a typical scenario, where Figure 4 (a) is a typical scenario 1. Figure 4 (b) is typical scenario 2. Figure 4 (c) is typical scenario 3. Figure 4 (d) is typical scenario 4.

[0079] Figure 5 Provides stacking diagrams for extreme scenarios, including Figure 5 (a) is extreme scenario 1, Figure 5 (b) is extreme scenario 2.

[0080] Figure 6 is the change diagram of pumped storage output, where Figure 6 (a) is extreme scenario 1, Figure 6 (b) is extreme scenario 2.

[0081] Figure 7 is the real-time reservoir capacity change diagram, where Figure 7 (a) is extreme scenario 1, Figure 7 (b) is extreme scenario 2.

[0082] Figure 8 It is a structural block diagram of the present invention. DETAILED DESCRIPTION

[0083] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0084] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0085] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0086] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0087] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0088] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0089] Example 1

[0090] The present invention provides a method for optimizing the multi-year capacity of pumped storage considering the continuous low output of wind and solar power, comprising:

[0091] First, the objective function of the pumped storage capacity optimization model is determined, and the goal is to minimize the optimal system comprehensive cost, where the cost items include the investment depreciation cost of pumped storage, the coal consumption cost of thermal power, the start-up and shutdown cost of the unit, the power abandonment cost and the load shedding cost. Each cost is calculated for each typical scenario, and the weighted sum is performed according to the scenario weight to obtain the system comprehensive cost. Secondly, the pumped storage construction constraint is incorporated, and the investment decision of pumped storage is constrained in combination with the construction scale limit of the pumped storage power station and the relationship between unit construction and output to ensure the feasibility of the planning scheme. After that, based on the output and load fluctuation characteristics of wind power and photovoltaic power, representative typical days are selected to construct typical scenario constraints, comprehensively considering the state constraints of thermal power units, output constraints of thermal power units, start-up and shutdown constraints, spare capacity constraints, pumped storage operation constraints, new energy power generation output constraints, load shedding constraints, power balance constraints, flow safety constraints, and system total spare capacity constraints. Then, based on the statistical analysis of historical wind power, photovoltaic and load data, the low output standard is set, the extreme wind and solar continuous low output scenario is identified and extracted, and the extreme scenario constraints are constructed. On the basis of typical scenario constraints, the load shedding constraints are appropriately relaxed to allow a higher degree of load shedding. Extreme scenario variables are not included in the objective function, and only the system safety verification is performed through constraints to ensure that the planning scheme not only takes into account the economic and consumption requirements, but also has the risk resistance and power supply guarantee level under extreme weather conditions. Finally, with the goal of minimizing the optimal comprehensive cost of the system, considering the pumped storage construction constraints, typical scenario constraints, and extreme scenario constraints, a multi-year capacity optimization model for pumped storage considering the continuous low output of wind and solar power is constructed. Using several typical scenarios and extreme scenarios as input, the solver is used for optimization and solution to obtain the capacity optimization configuration plan for pumped storage.

[0092] The above describes the modeling process of the multi-year capacity optimization method for pumped storage considering the continuous low output of wind and solar power, including the following steps, and its flow chart is as follows: Figure 1 shown.

[0093] Step 1: This model aims to minimize the overall system cost, taking into account multiple factors such as the investment cost of the pumped storage power station, the operating cost of the thermal power unit, the power abandonment loss cost, and the load shedding cost, and performs a weighted summation of multiple typical scenarios. Its objective function can be expressed as:

[0094]

[0095] Where: k refers to the typical scenario number; h refers to the year number; t refers to the time number; w refers to the new energy base number; n refers to the load node number; g refers to the thermal power unit number; N K is the total number of typical scenes; N H is the capacity planning period; T is the total duration of the calculation cycle, which is 168; N Wis the total number of new energy bases; N N is the total number of load nodes; N G is the number of thermal power units; P k is the sampling probability of each typical scene; q h K is the conversion factor of weekly operating expenses to annual operating expenses; w K is the penalty coefficient for abandonment of renewable energy; n is the load shedding penalty coefficient; The new energy output of the system at time t is predicted, is the new energy output actually consumed by the system at time t; is the load shedding amount of each load node; C g,Ge is the slope of the approximated coal consumption function; C g,min The coal consumption cost of each thermal power unit with the minimum technical output; is the actual output of the thermal power unit, P g,min is the minimum technical output of each thermal power unit; S gz is the shutdown cost coefficient of thermal power units; S gy is the startup cost coefficient of thermal power units; It is the 0-1 state variable of the thermal power unit; It is the 0-1 shutdown action variable of the thermal power unit; is the thermal power unit 0-1 startup action variable; r h is the discount factor for year h; It is the investment cost of the pumped storage unit.

[0096]

[0097]

[0098] Where: ps refers to the number of the pumped storage power station; c refers to the number of the constant speed and constant frequency pumped storage unit in the pumped storage power station ps; v refers to the number of the variable speed and constant frequency pumped storage unit in the pumped storage power station ps; N PS is the number of pumped storage power stations; C c,h , C v,h Y is the investment depreciation coefficient of each pumped storage unit; c,h , Y v,h is the construction state variable of each pumped storage unit; r m,c / v is the equal annual value coefficient of the c / v of the pumped storage unit, i is the discount rate, which is 6%, and m is the operating life of the c / v of the pumped storage unit.

[0099] Step 2: In order to ensure the feasibility of the optimization plan, the investment and construction constraints of pumped storage are introduced into the model. It mainly includes the following aspects:

[0100] 1) Annual maximum investment and construction constraints

[0101]

[0102] Where: Indicates the maximum construction capacity of constant speed unit c; Indicates the maximum investment capacity of variable speed unit v; represents the maximum construction capacity in the hth year; X c,h , X v,h It is the construction action variable of each pumped storage unit.

[0103] 2) Maximum investment and construction constraints for a single power station

[0104] Consider the construction progress and resource constraints, ensure planning feasibility and safety, and constrain the maximum investment and construction capacity of each pumped-storage power station.

[0105]

[0106] Where: It indicates the maximum investment capacity of the power station during its entire life cycle.

[0107] 3) Constraints on the order of construction of power plants

[0108]

[0109] Where: X ps,h Represents the construction action variable of power station ps; the above formula indicates that power station ps1 is constructed before ps2.

[0110] 4) Constraints on the order of construction of power station units

[0111] Y c ≤Y ps ,c∈ps(7)

[0112] Y v ≤Y ps ,v∈ps(8)

[0113] The above formula indicates that the power station ps is put into construction before the units c and v.

[0114] 5) Constraints on the relationship between investment and construction and unit output

[0115]

[0116]

[0117]

[0118]

[0119] The above formula indicates that only when the unit is under construction can it participate in power generation or water pumping.

[0120] 6) Constraints on the relationship between investment and construction actions and status

[0121] Similar to the start-stop constraints of thermal power units, the construction action variable X is also set c,h And the investment state variable Y c,h And constrain the relationship between the two.

[0122] Y c / v,h -Y c / v,h-1 =X c / v,h (13)

[0123] X c / v,h ≤Y c / v,h (14)

[0124] Step 3: Based on historical wind and load data, select a representative typical week and build typical scenario constraints. The main constraints include:

[0125] 1) Thermal power unit status constraints

[0126]

[0127]

[0128] The above formula represents the coupling relationship between the start-stop state variables and the start-stop action variables of the thermal power unit.

[0129] 2) Operation constraints of thermal power units

[0130] The output of thermal power units must meet the minimum technical output and installed capacity restrictions, and reserve spare capacity to cope with sudden increases or decreases in the output of renewable energy.

[0131]

[0132]

[0133]

[0134] Where: P g,min is the minimum technical output of thermal power unit g; P g,max The maximum technical output of thermal power unit g; is the maximum upward climbing rate of thermal power unit g; is the maximum downward climbing rate of thermal power unit g.

[0135] 3) Minimum continuous start and stop time constraints of the unit

[0136]

[0137]

[0138] Where: Indicates the minimum continuous start-up and shutdown time of thermal power units;

[0139] 4) Thermal power unit standby constraints

[0140]

[0141]

[0142]

[0143]

[0144] Where: Indicates the upward reserve of thermal power unit g; Indicates the downward reserve of thermal power unit g; T r Indicates the spinning standby response time (10 minutes).

[0145] 5) Constraints on pumped storage units

[0146] The constant speed and frequency pumped storage unit is modeled as follows:

[0147]

[0148]

[0149]

[0150] Where: Indicates the actual power generation output of constant speed pumped storage unit c; Indicates the upward reserve of constant speed pumped storage unit c; Indicates the maximum and minimum power output of the constant speed pumped storage unit c; represents the power generation state variable of the constant speed pumped storage unit c; Indicates the downward reserve of constant speed pumped storage unit c; represents the actual pumping power of the constant speed pumped storage unit c;

[0151] represents the constant speed pumping power of the constant speed pumped storage unit c; Represents the pumping state variable of the constant speed pumped storage unit c.

[0152] At the same time, the variable speed constant frequency pumped storage unit is modeled, namely:

[0153]

[0154]

[0155]

[0156]

[0157] Where: Indicates the actual power generation output of variable speed pumped storage unit v; represents the actual pumping power of variable speed pumped storage unit v; represents the power generation state variable of the variable speed pumped storage unit v; represents the pumping state variable of the variable speed pumped storage unit v; Indicates the maximum and minimum power generation output of variable speed pumped storage unit v; Indicates the maximum and minimum pumping power of variable speed pumped storage unit v; Indicates the upward reserve of variable speed pumped storage unit v; Indicates the downward standby of the variable speed pumped storage unit v.

[0158] Pumped storage cannot be in power generation and pumping state at the same time.

[0159]

[0160] In addition, it is necessary to construct a storage capacity balance constraint:

[0161]

[0162]

[0163]

[0164]

[0165] Where: represents the real-time storage capacity of the pumped storage power station ps; represents the initial storage capacity of the pumped storage power station ps; represents the storage capacity of the pumped storage power station ps at time T; η p and η g represent the pumping and power generation efficiencies, respectively; and They represent the maximum storage capacity and minimum storage capacity of the pumped storage power station ps respectively.

[0166] 6) Constraints on the operation of new energy power

[0167] First, the power generation needs to meet the constraint of being less than the resource amount.

[0168]

[0169] Where: represents the actual wind and solar power of new energy base w at time t under typical scenario k; represents the predicted wind and solar power of new energy base w at time t under typical scenario k;

[0170] At the same time, it is necessary to ensure that the output of new energy is within a reasonable consumption range.

[0171]

[0172] Where: μ represents the reasonable consumption rate of new energy, which is taken as 95% in this paper.

[0173] 7) Load shedding constraints

[0174]

[0175] Where: It represents the upper limit of the total load shedding under the typical scenario k.

[0176] 8) Power balance constraints

[0177]

[0178] Where: D n,t,h represents the injected power of node n.

[0179] 9) Power flow safety constraints

[0180]

[0181] Where: P l,min , P l,max They represent the lower and upper limits of the transmission power of line l respectively; and They represent the power flow distribution factors of the pumped storage power station ps, thermal power unit g, new energy base w and load node n on the line l respectively.

[0182] 10) System total backup constraints

[0183]

[0184]

[0185] Where: ω is the spinning reserve rate, which is taken as 5% in this paper; is the maximum load of the system under typical scenario k; ω w It represents the coefficient of the spinning reserve capacity increased to cope with the random fluctuation of renewable energy, and this paper takes 25%.

[0186] Step 4: In order to improve the reliability and risk resistance of the system under extreme weather conditions, identify and screen extreme low output scenarios based on the analysis of historical wind power, photovoltaic and load data.

[0187] The criteria for extreme scenarios where the wind and solar power output is continuously low are as follows:

[0188]

[0189] t2-t1≥θ (46)

[0190] This paper sets the average daily output of wind and solar power as ρ ave Less than the rated output of new energy ρ max When the power consumption is α times (10% in this paper) and the duration exceeds θ hours (72 in this paper), it is determined that an extreme continuous low output scenario of wind and solar power has occurred.

[0191] For these extreme scenarios, the variables in various power sources and pumped storage constraints are replaced with variables under extreme scenarios, and extreme scenario constraints are introduced (taking load shedding constraint (40), power balance constraint (41), and flow safety constraint (42) as examples):

[0192]

[0193]

[0194]

[0195] Where: Indicates the upper limit of the total load shedding in extreme scenario e.

[0196] By analogy, equations (15)-(39) and (43)-(44) are rewritten.

[0197] Step 5: With the goal of minimizing the optimal comprehensive cost of the system, considering the constraints of pumped storage construction, typical scenarios, and extreme scenarios, a pumped storage multi-year capacity optimization model considering the continuous low output of wind and solar power is constructed. Furthermore, considering the load demand, wind power and photovoltaic output characteristics of the power system in different seasons, several typical scenarios and extreme scenarios are introduced as model inputs, and the operating parameters and investment cost coefficients of the pumped storage power station and units to be built are given. Set the appropriate solution accuracy, use the mathematical optimization solver to solve the constructed capacity optimization model, find the global optimal solution that achieves the best comprehensive cost within the constraints, and obtain the pumped storage multi-year capacity optimization configuration plan.

[0198] Example 2

[0199] Taking the adapted IEEE-RTS79 as an example for case analysis, the hydropower units and some thermal power units are replaced by new energy bases. After replacement, the installed capacity of thermal power is 4000MW, the installed capacity of wind power is 2000MW, and the installed capacity of photovoltaic power is 2000MW. Two pumped storage power stations to be built are set up, of which four constant-speed pumped storage units and four variable-speed pumped storage units can be built in each power station, with a total pumped storage capacity of 960MW to be built. The parameters of the pumped storage power station and units to be built are shown in Tables 1 to 3. The maximum load of the system is 4000MW, and the wind and solar output and load data are from actual statistical data of a province in Northwest my country. The example uses four typical weeks and two extreme weeks with hourly resolution. The accuracy of the model solution is 0.1%. The program is based on MATLAB, and the commercial solution software Gurobi is used as the solver.

[0200] Table 1 Pumped storage power station construction parameters

[0201]

[0202]

[0203] The constant speed pumped storage unit and variable speed pumped storage unit each include one type, and the parameters are as follows:

[0204] Table 2 Single unit parameters of constant speed pumped storage unit

[0205]

[0206] Table 3 Single unit parameters of variable speed pumped storage unit

[0207]

[0208] In order to analyze the system demand and dispatch characteristics under different scenarios, this paper constructs the load curve and wind and solar power generation curve. The load curve and wind and solar output curve are based on typical seasonal demand characteristics. Typical weeks in spring, summer, autumn and winter are selected to reflect the average renewable energy output level and load characteristics of each season. For extreme scenarios, it is believed that the renewable energy output will maintain a continuous low level for a certain period of time, forming a continuous low output state. The selected load curves and wind and solar resource curves are as follows: Figure 2 , Figure 3 shown.

[0209] According to the established pumped storage capacity optimization model considering the continuous low output of extreme wind and solar power, the results of pumped storage capacity configuration are summarized as shown in Table 4 based on the typical scenario example data.

[0210] Table 4 Typical scenario pumped storage capacity configuration results

[0211]

[0212] At the same time, the output accumulation curve of each unit is obtained, such as Figure 4 shown.

[0213] Figure 4 The output of each unit and the pumped storage power generation in four typical weeks are shown. It can be seen that pumped storage tends to pump water when the wind and solar power are strong, and to generate power when the system power demand is high and the wind and solar power output is small. It can be seen that pumped storage and wind and solar power output show a complementary trend, which smooths the volatility of wind and solar power output and alleviates the peak load pressure of the system.

[0214] Based on the above typical scenario case analysis, extreme scenarios are further introduced to analyze their impact on the investment and construction demand of pumped storage units. The pumped storage capacity configuration results considering extreme scenarios are shown in Table 5.

[0215] Table 5 Pumped storage capacity configuration results considering extreme scenarios

[0216]

[0217] In extreme scenarios, the low output of wind and solar power in extreme scenarios puts higher requirements on the regulation ability and reliability of the system. The above results show that after introducing extreme scenarios and adding extreme scenario constraints, the investment demand for pumped storage power stations is increased by 25% compared with the investment demand for pumped storage power stations that only consider typical scenarios.

[0218] The impact of extreme supply guarantee scenarios on the model solution results is further analyzed from the three aspects of green, economic and safety, as shown in Table 6. The load shedding in extreme scenarios is not considered, and the pumped storage capacity configuration scheme is set to be consistent with the typical scenario, and only the load shedding obtained by optimizing the extreme scenario is obtained.

[0219] Table 6 Comparison of solution results analysis considering and not considering extreme scenarios

[0220]

[0221] After considering extreme scenarios, the scale of investment and construction of pumped storage increased, the system power abandonment rate decreased, and the level of new energy consumption increased. However, due to the increase in the total cost of the system, the overall economic efficiency decreased. At the same time, the load shedding in extreme supply guarantee scenarios decreased, which significantly enhanced the safety of the system in extreme situations.

[0222] At the same time, the demand for pumped storage varies under different supply requirements. Table 7 is drawn up to analyze the impact of different supply requirements on the scale of pumped storage investment and construction.

[0223] Table 7 Investment and construction of pumped storage under different supply guarantee requirements

[0224]

[0225] As the supply guarantee requirements increase, the system's load shedding rate decreases, while the capacity demand for pumped storage increases accordingly. This shows that under high supply guarantee requirements, in order to reduce load shedding and improve the system's power supply reliability, the system needs to rely on more pumped storage capacity to provide flexible adjustment capabilities.

[0226] In addition, the output stacking diagrams of each unit, pumped storage, and wind and solar power under extreme scenarios are studied, such as Figure 5 shown.

[0227] exist Figure 5 It can be observed that the phenomenon of wind and solar power abandonment has been significantly reduced, but at the same time, the output fluctuation of thermal power units has intensified. In addition, it shows that load shedding occurred in some periods, which is unacceptable under normal typical operating conditions, reflecting the severe test faced by the system in dealing with supply and demand imbalance in extreme supply guarantee scenarios.

[0228] Further analyze the mechanism of pumped storage participating in extreme water supply guarantee, draw the pumped storage output change diagram and the reservoir real-time storage capacity change diagram as shown in the figure. Figures 6-7 shown.

[0229] from Figure 6 It can be seen that in order to cope with extreme low output scenarios, pumped storage stores energy in the upper reservoir by pumping water in advance before the low output period arrives. When the low output period arrives, the pumped storage unit releases the energy stored in the upper reservoir to ensure power supply. This process can also be seen from Figure 7 This has been verified in the literature: before the low-output period, the reservoir capacity will reach a higher level in advance, providing sufficient reserves for subsequent energy release.

[0230] Therefore, in order to meet the supply guarantee requirements in extremely low output scenarios, the model plans more pumped storage unit capacity. Before the low output period arrives, the pumped storage unit reserves energy by pumping water in advance; during the low output period, the stored energy is gradually released to achieve the peak load guarantee function on a weekly time scale, thereby effectively alleviating the pressure of power supply guarantee in extremely continuous low output conditions.

[0231] If multi-year capacity optimization configuration is performed, the capacity planning period N needs to be changed. H , and make corresponding parameter configuration and adjustments to optimize the solution.

[0232] Example 3

[0233] like Figure 8 As shown, the present invention provides a pumped storage multi-year capacity optimization system taking into account the continuous low output of wind and solar power, including:

[0234] Objective function construction module, which constructs an objective function that comprehensively considers economic efficiency and new energy consumption needs;

[0235] The first constraint construction module combines the construction scale limit and the unit operation relationship to constrain investment decisions to ensure the feasibility of the plan and construct pumped storage construction constraints;

[0236] The second constraint building module builds typical scenario constraints by comprehensively considering various power sources and pumped storage operations, spare capacity, upper and lower limits of transmission lines, and power balance conditions;

[0237] The third constraint construction module identifies and extracts low-output scenarios based on historical data, moderately relaxes load shedding restrictions, and constructs extreme scenario constraints for safety verification;

[0238] The model construction and solution module is composed of objective function, pumped storage construction constraints, typical scenario constraints and extreme scenario constraints. It takes the typical weekly scenario and extreme weekly scenario as input, uses the solver to perform optimization and solution, and finally obtains the optimal configuration plan of pumped storage capacity.

[0239] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0240] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A multi-year capacity optimization method for pumped storage considering continuous low output of wind and solar power, characterized in that: The following steps are involved: Step 1: Construct an objective function that comprehensively considers economic efficiency and new energy consumption needs; Step 2: Combine the construction scale limit and the unit operation relationship, constrain the investment decision to ensure the feasibility of the plan, and construct the pumped storage construction constraints; Step 3: Consider various power sources and pumped storage operations, spare capacity, upper and lower limits of transmission lines, and power balance conditions to construct typical scenario constraints; Step 4: Identify and extract low-output scenarios based on historical data, moderately relax load shedding restrictions, and build extreme scenario constraints for safety verification; Step 5: A multi-year capacity optimization model for pumped storage considering continuous low output of wind and solar power is constructed, which is composed of objective function, pumped storage construction constraints, typical scenario constraints and extreme scenario constraints. The typical weekly scenario and extreme weekly scenario are used as input, and the solver is used for optimization and solution, and finally the optimal configuration plan of pumped storage capacity is obtained.

2. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 1 is characterized in that: In step 1, an objective function is constructed that comprehensively considers economic efficiency and new energy consumption needs, including: The goal is to minimize the overall system cost. The objective function includes: investment depreciation, coal consumption, start-up and shutdown, power abandonment and load shedding costs, and the weighted sum is calculated according to the weight of typical scenarios to convert them into equal annual values. The specific mathematical expression of the objective function is as follows: Where: k refers to the typical scenario number; h refers to the year number; t refers to the time number; w refers to the new energy base number; n refers to the load node number; g refers to the thermal power unit number; N K is the total number of typical scenes; N H is the capacity planning period; T is the total duration of the calculation cycle, which is 168; N W is the total number of new energy bases; N N is the total number of load nodes; N G is the number of thermal power units; P k is the sampling probability of each typical scene; q h K is the conversion factor of weekly operating expenses to annual operating expenses; w K is the penalty coefficient for abandonment of renewable energy; n is the load shedding penalty coefficient; The new energy output of the system at time t is predicted, is the new energy output actually consumed by the system at time t; is the load shedding amount of each load node; C g,Ge is the slope of the approximated coal consumption function; C g,min The coal consumption cost of each thermal power unit with the minimum technical output; is the actual output of each thermal power unit, P g,min is the minimum technical output of each thermal power unit; S gz is the shutdown cost coefficient of thermal power units; S gy is the startup cost coefficient of thermal power units; It is the 0-1 state variable of the thermal power unit; It is the 0-1 shutdown action variable of the thermal power unit; is the thermal power unit 0-1 startup action variable; r h is the discount factor for year h; The investment cost of the pumped storage unit; Where: ps refers to the number of the pumped storage power station; c refers to the number of the constant speed and constant frequency pumped storage unit in the pumped storage power station ps; v refers to the number of the variable speed and constant frequency pumped storage unit in the pumped storage power station ps; N PS is the number of pumped storage power stations; C c,h , C v,h Y is the investment depreciation coefficient of each pumped storage unit; c,h , Y v,h is the construction state variable of each pumped storage unit; r m,c / v is the equal annual value coefficient of the c / v of the pumped storage unit, i is the discount rate, which is 6%, and m is the operating life of the c / v of the pumped storage unit.

3. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 1 is characterized in that: In step 2, combined with the construction scale limit and the unit operation relationship, the investment decision is constrained to ensure the feasibility of the plan, and the pumped storage construction constraints are constructed, including: annual maximum investment constraints, single power station maximum investment constraints, power station construction sequence constraints, power station unit construction sequence constraints, investment and construction and unit output relationship constraints, investment and construction action and status relationship constraints.

4. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 1 is characterized in that: In step three, various power sources and pumped storage operations, reserve capacity, upper and lower limits of transmission lines and power balance conditions are comprehensively considered to construct typical scenario constraints, including: thermal power unit status constraints, thermal power unit operation constraints, unit minimum continuous start-up and shutdown time constraints, thermal power unit reserve constraints, pumped storage unit constraints, new energy power operation constraints, load shedding constraints, power balance constraints, flow safety constraints and total reserve constraints.

5. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 4 is characterized in that: The constraints of pumped storage units are modeled for constant speed and frequency units and variable speed and constant frequency units respectively; The constant speed and frequency pumped storage unit is modeled as follows: Where: Indicates the actual power generation output of constant speed pumped storage unit c; Indicates the upward reserve of constant speed pumped storage unit c; Indicates the maximum and minimum power output of the constant speed pumped storage unit c; represents the power generation state variable of the constant speed pumped storage unit c; Indicates the downward reserve of constant speed pumped storage unit c; represents the actual pumping power of the constant speed pumped storage unit c; represents the constant speed pumping power of the constant speed pumped storage unit c; represents the pumping state variable of the constant speed pumped storage unit c; At the same time, the variable speed constant frequency pumped storage unit is modeled, namely: Where: Indicates the actual power generation output of variable speed pumped storage unit v; represents the actual pumping power of variable speed pumped storage unit v; represents the power generation state variable of the variable speed pumped storage unit v; represents the pumping state variable of the variable speed pumped storage unit v; Indicates the maximum and minimum power generation output of variable speed pumped storage unit v; Indicates the maximum and minimum pumping power of variable speed pumped storage unit v; Indicates the upward reserve of variable speed pumped storage unit v; Indicates the downward reserve of variable speed pumped storage unit v; Pumped storage cannot be in power generation and pumping state at the same time. In addition, it is necessary to construct a storage capacity balance constraint: Where: Represents the real-time storage capacity of the pumped storage power station ps; represents the initial storage capacity of the pumped storage power station ps; ps represents the storage capacity of the pumped storage power station at time T; η p and η g denote the pumping and power generation efficiencies, respectively; and They represent the maximum storage capacity and minimum storage capacity of the pumped storage power station ps respectively.

6. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 4 is characterized in that: In the operation constraints of new energy power, the output of new energy is less than the total resource volume, and the restriction on the consumption rate of new energy is considered: First, the power generation needs to meet the constraint of being less than the resource amount; Where: represents the actual wind and solar power of new energy base w at time t under typical scenario k; represents the predicted wind and solar power of new energy base w at time t under typical scenario k; At the same time, it is necessary to ensure that the output of new energy is within a reasonable consumption range; In the formula: μ represents the reasonable consumption rate of new energy, which is taken as 95%.

7. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 4 is characterized in that: In the load shedding constraint, the total load shedding amount in a single scenario is less than a certain threshold: Where: It represents the upper limit of the total load shedding under the typical scenario k.

8. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 4 is characterized in that: The total reserve constraint takes into account the reserve capacity demand due to load forecast error and new energy forecast error; Where: ω is the spinning reserve rate, which is 5%; is the maximum load of the system under typical scenario k; ω w It represents the coefficient of the spinning reserve capacity increased to cope with the random fluctuation of renewable energy, which is taken as 25%.

9. The method for optimizing the multi-year capacity of pumped storage considering continuous low output of wind and solar power according to claim 1 is characterized in that: In step 4, the extreme scenario constraints further relax the load shedding restrictions based on the typical scenario constraints. At the same time, the extreme scenario variables are not included in the objective function, but only included in the constraints for extreme supply security inspection; Replace the variables in various power sources and pumped storage constraints with variables in extreme scenarios, introduce extreme scenario constraints, and for storage capacity balance constraints (12)-(15): And so on, the remaining typical scenario constraints are rewritten.

10. Considering the continuous low output of wind and solar power, the pumped storage multi-year capacity optimization system is characterized by: include: Objective function construction module, which constructs an objective function that comprehensively considers economic efficiency and new energy consumption needs; The first constraint construction module combines the construction scale limit and the unit operation relationship to constrain investment decisions to ensure the feasibility of the plan and construct pumped storage construction constraints; The second constraint building module builds typical scenario constraints by comprehensively considering various power sources and pumped storage operations, spare capacity, upper and lower limits of transmission lines, and power balance conditions; The third constraint construction module identifies and extracts low-output scenarios based on historical data, moderately relaxes load shedding restrictions, and constructs extreme scenario constraints for safety verification; The model construction and solution module is composed of objective function, pumped storage construction constraints, typical scenario constraints and extreme scenario constraints. It takes the typical weekly scenario and extreme weekly scenario as input, uses the solver to perform optimization and solution, and finally obtains the optimal configuration plan of pumped storage capacity.

Images