Micro-grid energy storage optimal configuration method and system based on steady-state balance and transient verification

Abstract

The invention discloses a microgrid energy storage optimal configuration method and system based on steady-state balance and transient verification. The method comprises the steps of obtaining model input data including load characteristics, a construction site, meteorological data, economic cost and policy subsidy; establishing models of all parts of the wind and light storage micro-grid in a steady state, wherein the models comprise power models output by photovoltaic power generation equipment, a wind driven generator and an energy storage battery in a steady state condition; carrying out electric power and electric quantity balance calculation to obtain a plurality of reasonable configuration schemes; and performing scheme comparison and selection by taking the cost per kilowatt-hour as an optimization target: verifying the transient stability of each scheme by adopting an electromechanical transient simulation method, and finally selecting a scheme which can pass the transient stability verification and has the lowest cost per kilowatt-hour as an optimal configuration scheme. According to the technical scheme, factors such as loads, sites, meteorology, economy and policies are comprehensively considered, the characteristics of the wind and light storage micro-grid system are reflected more practically and comprehensively, and economical efficiency and reliability of configuration of the wind and light storage micro-grid are considered.

Description

Technical Field

[0001] The present invention relates to a method for optimizing configuration of a wind, solar and energy storage microgrid, and in particular to a method and system for optimizing configuration of a microgrid energy storage based on steady-state balance and transient verification. Background Art

[0002] With the intensification of environmental pollution and the reduction of fossil fuels, my country proposed the "dual carbon" goal in 2020, that is, to achieve carbon peak by 2030 and carbon neutrality by 2060, and renewable energy power generation has developed rapidly. According to statistics from the National Energy Administration, by the end of April 2023, my country's wind power installed capacity will be 380 million kilowatts, photovoltaic power generation installed capacity will be 440 million kilowatts, and the total installed capacity of wind power and photovoltaic power will exceed 800 million kilowatts, reaching 820 million kilowatt-hours. The rapid development of new energy and the continuous updating of energy storage technology have made wind, solar and energy storage microgrids feasible and economical in specific scenarios.

[0003] Microgrid, also known as microgrid, is a small power system that includes distributed power generation, energy storage devices, protection and control equipment, and loads. Networked microgrids are generally used in industrial parks, enterprises, communities, hospitals, schools and other areas. They have two operating modes: grid-connected and independent. In the grid-connected working mode, they are connected to the distribution network to achieve two-way energy exchange; in the case of power outages in the external power grid, they can be switched to island operation mode to improve power supply reliability. Independent microgrids are generally used in remote areas such as rural areas and islands that are not covered by large power grids. They are not connected to conventional power grids, operate in islands, and use their own distributed power sources to meet the load requirements within the microgrid. The optimal configuration of the capacity of a microgrid refers to the optimization of a certain evaluation index of the microgrid by reasonably allocating the capacity of power and energy storage. The indicators for evaluating whether the configuration of microgrid energy storage capacity is reasonable mainly include economy, reliability, environmental protection, etc.

[0004] The existing technology mainly has the following shortcomings:

[0005] (1) The factors considered when modeling the components of the microgrid are relatively limited, and factors such as load, site, meteorology, economy, and policy are not fully considered.

[0006] (2) Conventional planning methods measure the economic efficiency of microgrid energy storage mainly based on investment cost, without taking into account load power consumption. This cannot accurately reflect the operating characteristics of the microgrid, and therefore the economic evaluation is not accurate enough.

[0007] (3) The transient stability of the microgrid is not considered. The system may lose stability when there is a large fluctuation in renewable energy, the start-up of large-capacity impact loads, or grid failure. Summary of the invention

[0008] The purpose of the present invention is to provide a microgrid energy storage optimization configuration method and system based on steady-state balance and transient verification, which can make up for the shortcomings of the existing technology while taking into account the simplicity of the model.

[0009] In order to achieve the above object, the solution of the present invention is:

[0010] A microgrid energy storage optimization configuration method based on steady-state balance and transient verification includes the following steps:

[0011] Step 1: Obtain model input data including load characteristics, construction sites, meteorological data, economic costs, and policy subsidies;

[0012] Step 2: Establish models of each part of the wind-solar-storage microgrid under steady-state conditions, including power models of photovoltaic power generation equipment, wind turbines, and energy storage battery output under steady-state conditions; and perform power balance calculations to obtain several reasonable configuration schemes;

[0013] Step 3: Taking the electricity cost as the optimization target, compare the several configuration schemes in step 2:

[0014] Step 4: Use the electromechanical transient simulation method to verify the transient stability of each solution, and finally select the solution that can pass the transient stability verification and has the lowest cost per kilowatt-hour as the optimal configuration solution.

[0015] In step 1 above, the model input data including load characteristics, construction site, meteorological data, economic cost, and policy subsidies are obtained, including: the load size, type, important load power, and annual electricity consumption must be clarified; the size, longitude and latitude, and altitude of the construction site must be clarified; the local wind and light resources must be clarified; and the local electricity price and policy subsidies must be clarified.

[0016] In the above step 2, the models of each part of the wind-solar-storage microgrid under steady state are established, including the power model of photovoltaic power generation equipment, wind turbines and energy storage battery output under steady state conditions; including,

[0017] Theoretical maximum output of photovoltaic power generation equipment P PV The calculation model is as follows:

[0018]

[0019] Where P PN is the output of the photovoltaic array under experimental conditions; k df is the photovoltaic derating factor; R T is the solar radiation in the current environment; R TS is the solar radiation in the test environment; b p is the temperature coefficient of power; T C is the current photovoltaic cell temperature; TCS is the photovoltaic cell temperature of the test environment;

[0020] Theoretical maximum output of wind turbine generator set P w The calculation model is as follows:

[0021] First calculate the wind speed v at the hub height of the wind turbine h :

[0022]

[0023] In the formula, v a is the wind speed at the anemometer height, in m / s; h h is the hub height of the wind turbine, in m; h a is the height of the anemometer, in meters; h0 is the surface roughness length, ln is the natural logarithm; the wind speed v at the hub height is determined according to the wind turbine output power curve given by the wind turbine manufacturer h The theoretical maximum output of a single wind turbine generator set is P w ;

[0024] The energy storage charging and discharging model is as follows: when the power generated by photovoltaic and wind turbines is greater than the load power consumption, the energy storage battery can be charged; when the power generated by photovoltaic and wind turbines cannot meet the load demand, the energy storage battery discharges to meet the load demand. The rated power of the energy storage battery is P ES .

[0025] In the above step 2, the power balance calculation is performed, including performing a power balance calculation with a step length of 1 hour and 8760 hours throughout the year, including a steady-state power balance calculation and a battery balance calculation, specifically including:

[0026] The steady-state power balance calculation model is as follows:

[0027]

[0028] Where n pv is the number of photovoltaic power generation equipment, P pv，i is the output of photovoltaic power generation equipment, and the number of wind turbines is n w , P w，i is the output of the wind turbine, n ES is the capacity of the energy storage battery, P ES，i P is the energy storage charging and discharging power per kilowatt-hour, Load，i is the load power;

[0029] The battery charge balance calculation model is as follows:

[0030]

[0031] In the formula, SES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency, η ES,c For charging efficiency.

[0032] In the above step 2, several reasonable configuration solutions are obtained, including several reasonable configuration solutions obtained according to the following constraints:

[0033] ① Photovoltaic and wind turbine output constraints: The output of photovoltaic power generation equipment P pv，i Not greater than the theoretical maximum output P PV , the output of wind turbine generator set P w，i Not greater than the theoretical maximum output P W ,Right now:

[0034] 0≤P pv，i ≤P PV

[0035] 0≤P w，i ≤P W

[0036] ② Energy storage charging and discharging power constraint: The charging and discharging power of energy storage shall not exceed the rated power, so the energy storage charging / discharging power P ES，i The following constraints are met:

[0037] 0≤P ES，i ≤P ES

[0038] Where P Es is the energy storage rated power;

[0039] ③ Energy storage battery power SOC constraint:

[0040] The remaining battery capacity SOC S of the energy storage battery ES，i At the lower limit of remaining power control SOC min And the remaining power control upper limit SOC max Between, that is:

[0041] SOC min ≤S ES，i ≤SOC max

[0042] ④ Power supply reliability constraint: Set the uninterrupted operation time of important loads to t imp , in hours;

[0043] That is, the capacity of the energy storage should not be less than the capacity of the important load at t imp The amount of electricity consumed, and the discharge power is not less than the power consumed by the important load, that is:

[0044]

[0045] Where W ES is the energy storage capacity, in kWh; P imp is the important load power, in kW; η ES,d is the discharge efficiency.

[0046] In step 2 above, several reasonable configuration schemes are obtained, including configuration scheme X k ={n pv，k , n w,k , n ES,k}, k=1,2,…μ is calculated as follows:

[0047]

[0048] Where n pv P is the number of photovoltaic power generation equipment configured; pv，i is the output of photovoltaic power generation equipment, P PV is the theoretical maximum output of photovoltaic power generation equipment; n w is the number of wind turbine generator sets; P w，i is the output of the wind turbine, P W is the theoretical maximum output of the wind turbine; n ES is the capacity of the energy storage battery; P ES，i P is the charging / discharging power of the energy storage battery per kilowatt-hour; Load，i is the load power; S ES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency; P imp is the important load power; t imp The non-stop operation time for important loads; SOC min SOC is the lower limit of remaining power control. max is the upper limit of remaining power control, and μ is the number of configuration schemes.

[0049] In the above step 3, the objective function COE is expressed as:

[0050]

[0051] In the formula, N is the life of the project, C0 is the initial investment cost, C om，i is the operation and maintenance cost, C repla，i is the replacement cost, I sub,i For policy subsidies, I rv (i) is the residual value in the i-th year, W load is the electricity consumed by the load in one year, and λ is the discount rate.

[0052] In step 3 above, configure solution X k Substitute the calculation model of COE into the cost per kilowatt-hour in turn to calculate COE (X k ), and then sort them from low to high according to the electricity cost, and get a set of solutions: Y j ={n pv，j , n w,j , n ES，j}, j=1,2,…μ, satisfies: COE(Y1)<COE(Y2)<COE(Y3)…COE(Y μ ).

[0053] The specific content of the above step 4 is,

[0054] Step 41: firstly, for the jth configuration scheme Y j Perform power flow calculation. When the following conditions are met, go to step 42. Otherwise, this solution is eliminated and step 41 is repeated for the j+1th configuration solution. Condition 1: whether the power flow calculation converges. Condition 2: whether the voltage of each node is within the allowable range. Condition 3: whether each component is overloaded.

[0055] Step 42: Verify configuration scheme Y using electromechanical transient simulation method j Under the transient stability of large fluctuations in new energy, large-capacity impact load startup, and power grid failure, if the voltage and frequency can be kept stable, it means that the configuration scheme meets the transient stability requirements, and the output scheme Y j Otherwise, this solution is eliminated and the j+1th configuration solution is transferred to step 41, and finally the solution that can pass the transient stability check and has the lowest cost per kilowatt-hour is selected as the optimal configuration solution.

[0056] A microgrid energy storage optimization configuration system based on steady-state balance and transient verification, comprising:

[0057] Data acquisition module, used to obtain model input data including load characteristics, construction sites, meteorological data, economic costs, and policy subsidies;

[0058] The configuration scheme construction model is used to establish the models of each part of the wind-solar-storage microgrid under steady-state conditions, including the power model of photovoltaic power generation equipment, wind turbines and energy storage battery output under steady-state conditions; and perform power balance calculations to obtain several reasonable configuration schemes;

[0059] The scheme comparison module is used to compare several configuration schemes output by the configuration scheme construction model, taking the cost per kilowatt-hour as the optimization target: and,

[0060] The optimal configuration scheme output module is used to verify the transient stability of each scheme using the electromechanical transient simulation method, and finally select the scheme that can pass the transient stability verification and has the lowest cost per kilowatt-hour as the optimal configuration scheme.

[0061] After adopting the above scheme, the present invention has the following significant advantages compared with the prior art:

[0062] (1) The establishment process of the model of the present invention comprehensively considers factors such as load, site, meteorology, economy, and policy, and reflects the characteristics of the wind, solar, and energy storage microgrid system in a more practical and comprehensive manner.

[0063] (2) The present invention is based on steady-state power balance calculation to ensure that the supply and demand of microgrid load electricity is balanced at every moment;

[0064] (3) Using the cost per kilowatt-hour as an indicator to measure the economic efficiency of a microgrid can better reflect the operating characteristics of the microgrid and provide a more accurate evaluation of its economic efficiency.

[0065] (4) Based on transient stability verification, the present invention eliminates solutions that do not meet the system stability requirements, taking into account the economy and reliability of wind, solar, and energy storage microgrid configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a flow chart of the present invention;

[0067] Figure 2 It is a flow chart of outputting the optimal configuration scheme based on transient stability verification in the present invention. DETAILED DESCRIPTION

[0068] The technical solutions and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.

[0069] like Figure 1 As shown, the present invention provides a microgrid energy storage optimization configuration method based on steady-state balance and transient verification, comprising the following steps:

[0070] Step S1: Obtain model input data such as load characteristics, construction site, meteorological data, economic costs, policy subsidies, etc.:

[0071] 1. Load information: the size and type of load and collect load data. In terms of load type, it is necessary to clarify whether there is an important load. In terms of load data, load data accurate to the minute or hour level and annual load power consumption data are required.

[0072] 2. Site information: the size, longitude and latitude of the construction site, and altitude. The size of the site affects the layout of solar photovoltaic panels, wind turbines, and energy storage cabins; determining longitude and latitude is a prerequisite for collecting local meteorological data; altitude will affect the operation of equipment, and equipment capacity reduction needs to be considered in high-altitude areas.

[0073] 3. Meteorological data: local wind and light resource conditions. The number of hours of wind and light utilization in the same area is generally fixed.

[0074] 4. Economic information: local electricity prices and policy subsidies.

[0075] Step S2: Establish models of each part of the wind, solar and energy storage microgrid in steady state, and perform power balance calculation to obtain several reasonable configuration schemes;

[0076] In order to perform power balance calculations, it is necessary to model the various components of the microgrid, specifically to establish power models for the output of photovoltaic power generation equipment, wind turbines, and energy storage batteries under steady-state conditions.

[0077] 1. Theoretical maximum output of photovoltaic power generation equipment P PV The calculation model is as follows:

[0078]

[0079] Where P PN is the output of the photovoltaic array under experimental conditions; k df is the photovoltaic derating factor; R T is the solar radiation in the current environment; R TS is the solar radiation in the test environment; b p is the temperature coefficient of power; T C is the current photovoltaic cell temperature; T CS is the photovoltaic cell temperature in the test environment.

[0080] 2. Theoretical maximum output P of wind turbine w The calculation model is as follows:

[0081] First calculate the wind speed v at the hub height of the wind turbine h :

[0082]

[0083] In the formula, v ais the wind speed at the anemometer height, in m / s; h h is the hub height of the wind turbine, in m; h a is the height of the anemometer, in meters; h0 is the surface roughness length, and ln is the natural logarithm. According to the wind turbine output power curve given by the wind turbine manufacturer, the wind speed v at the hub height can be determined. h The theoretical maximum output of a single wind turbine generator set is P w .

[0084] 3. The energy storage charging and discharging model is as follows: when the power generated by photovoltaic and wind turbines is greater than the load power consumption, the energy storage battery can be charged; when the power generated by photovoltaic and wind turbines cannot meet the load demand, the energy storage battery is discharged to meet the load demand. The rated power of the energy storage battery is P ES .

[0085] 4. Power balance calculation: Perform power balance calculation with a step length of 1 hour and 8760 hours per year, including steady-state power balance calculation and battery balance calculation, specifically including:

[0086] The steady-state power balance calculation model is as follows:

[0087]

[0088] Where n pv is the number of photovoltaic power generation equipment, P pv，i is the output of photovoltaic power generation equipment, and the number of wind turbines is n w , P w，i is the output of the wind turbine, n ES is the capacity of the energy storage battery, P ES，i P is the energy storage charging and discharging power per kilowatt-hour, Load，i is the load power.

[0089] The battery charge balance calculation model is as follows:

[0090]

[0091] In the formula, S ES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency, η ES,c For charging efficiency.

[0092] 5. Inequality constraints:

[0093] ① Photovoltaic and wind turbine output constraints: The output of photovoltaic power generation equipment P pv，i Not greater than the theoretical maximum output P PV , the output of wind turbine generator set P w，i Not greater than the theoretical maximum output P W ,Right now:

[0094] 0≤P pv，i ≤P PV

[0095] 0≤P w，i ≤P W

[0096] ② Energy storage charging and discharging power constraint: The charging and discharging power of energy storage shall not exceed the rated power, so the energy storage charging / discharging power P ES，i The following constraints are met:

[0097] 0≤P ES，i ≤P ES

[0098] ③ Energy storage battery power SOC constraint:

[0099] The remaining battery capacity SOC of the energy storage battery is within the remaining battery capacity control lower limit SOC min And the remaining power control upper limit SOC max Between, that is:

[0100] SOC min ≤S ES，i ≤SOC max

[0101] ④ Power supply reliability constraint: If there is an important load, the energy storage configuration should ensure that the important load can run without power outage for a certain period of time as required. Set the important load uninterrupted operation time as t imp , in hours.

[0102] That is, the capacity of the energy storage should not be less than the capacity of the important load at t imp The amount of electricity consumed, and the discharge power is not less than the power consumed by the important load, that is:

[0103]

[0104] Where W ES is the energy storage capacity, in kWh; P imp is the important load power, in kW; η ES,d is the discharge efficiency.

[0105] In step S2, configure solution X k ={n pv，k , n w,k , nES,k}, k=1,2,…μ is calculated as follows:

[0106]

[0107] Where n pv P is the number of photovoltaic power generation equipment configured; pv，i is the output of photovoltaic power generation equipment, P PV is the theoretical maximum output of photovoltaic power generation equipment; n w is the number of wind turbine generator sets; P w，i is the output of the wind turbine, P W is the theoretical maximum output of the wind turbine; n ES is the capacity of the energy storage battery; P ES，i P is the charging / discharging power of the energy storage battery per kilowatt-hour; Load，i is the load power; S ES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency; P imp is the important load power; t imp The non-stop operation time for important loads; SOC min SOC is the lower limit of remaining power control. max is the upper limit of remaining power control, and μ is the number of configuration schemes.

[0108] S3. Take the electricity cost as the optimization target and compare the solutions:

[0109] The objective function COE can be expressed as:

[0110]

[0111] In the formula, N is the life of the project, C0 is the initial investment cost, C om，i is the operation and maintenance cost, Cr epla，i is the replacement cost, I sub，i For policy subsidies, I rv (i) is the residual value in the i-th year, W load is the electricity consumed by the load in one year, and λ is the discount rate.

[0112] The initial investment cost C0 includes: investment in photovoltaic power generation equipment, investment in wind turbines, and investment in energy storage. Photovoltaic power generation equipment investment: The investment C0 of a single photovoltaic power generation equipment PV , npv The total investment of photovoltaic power generation equipment is C PV n pv . Wind turbine investment: The investment of a single wind turbine is C W , n w The total investment of wind turbines is C W n w . Energy storage investment:

[0113] Initial investment cost of energy storage project C ES It is proportional to the scale of energy storage and can be expressed as follows:

[0114] C ES =K EPC ·W ES

[0115] In the formula, K EPC Indicates the EPC unit price per kilowatt-hour of energy storage.

[0116] The initial investment C0 is as follows:

[0117] C0=C PV +C W +C ES

[0118] Operation and maintenance cost C om，i :Including the operation and maintenance costs of photovoltaic arrays, wind turbines, and energy storage batteries. Operation and maintenance costs C om，i It can be considered as a constant value that does not change with time or changes in the system operating status, i≥1.

[0119] Replacement cost C repla，i : Replacement cost is the cost of replacing a component at the end of its life, specified by the life parameter in the component model, i ≥ 1.

[0120] Policy Subsidy I sub，i :All regions have corresponding subsidy policies for renewable energy power generation and supporting energy storage, which are generally related to capacity. Assume that the local wind power subsidy policy is β1 yuan per kilowatt, the photovoltaic power subsidy policy is β2 yuan per kilowatt, and the energy storage subsidy is β3 yuan per kilowatt-hour.

[0121]

[0122] Residual Value I rv (i): represents the residual value that is expected to be recovered at the end of the service life of the microgrid project. The residual value of the equipment in the i-th year is I rv (i) is proportional to the initial investment C0, and the proportionality coefficient is r rv (i) represents the depreciation rate in year i, as shown below:

[0123] Irv (i) = r rv (i) C0

[0124] satisfy:

[0125]

[0126] Configure Scheme X i Substitute COE in turn and sort from low to high to get a set of solutions: Y j ={n pv，j , n w，j , n ES，j}, j=1,2,…μ, satisfies: COE(Y1)<COE(Y2)<COE(Y3)…COE(Y μ ).

[0127] S4. Based on transient stability verification, output the optimal configuration solution:

[0128] like Figure 2 As shown, input the jth configuration scheme Y j , perform power flow calculation and judge: ①Whether the power flow calculation converges, ②Whether the voltage of each node is within the allowable range, and ③Whether each component is overloaded. When the above three conditions are met, the electromechanical transient simulation method is used to verify the transient stability of the microgrid under large fluctuations in new energy, large-capacity impact load startup, and power grid failure. Otherwise, eliminate this scheme and verify the j+1th scheme. Large fluctuations in new energy include the following expected accident sets: ①The solar radiation R in the current environment T Sudden drop, ②Sudden drop of wind speed V at the height of wind turbine hub h The start of large-capacity impact loads includes the following expected accident sets: ① A large-capacity impact load suddenly starts, and a large-capacity impact load suddenly stops. The power grid failure includes the following expected accident sets: ① A photovoltaic collection line fails, ② A wind power collection line fails, ③ A storage collection line fails, and ④ A load collection line fails. If the voltage and frequency can be kept stable, it means that the configuration scheme meets the transient stability requirements, and the output scheme Y j Otherwise, this solution is eliminated and the j+1th solution is verified, and finally the solution that can pass the transient stability verification and has the lowest cost per kilowatt-hour is selected as the preferred solution.

[0129] Based on the above method, the present invention also provides a microgrid energy storage optimization configuration system based on steady-state balance and transient verification, comprising:

[0130] Data acquisition module, used to obtain model input data including load characteristics, construction sites, meteorological data, economic costs, and policy subsidies;

[0131] The configuration scheme construction model is used to establish the models of each part of the wind-solar-storage microgrid under steady-state conditions, including the power model of photovoltaic power generation equipment, wind turbines and energy storage battery output under steady-state conditions; and perform power balance calculations to obtain several reasonable configuration schemes;

[0132] The scheme comparison module is used to compare several configuration schemes output by the configuration scheme construction model, taking the cost per kilowatt-hour as the optimization target: and,

[0133] The optimal configuration scheme output module is used to verify the transient stability of each scheme using the electromechanical transient simulation method, and finally select the scheme that can pass the transient stability verification and has the lowest cost per kilowatt-hour as the optimal configuration scheme.

[0134] Among them, the above modules realize their functions based on the aforementioned methods and will not be repeated here.

[0135] The above embodiments are only for illustrating 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 in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A microgrid energy storage optimization configuration method based on steady-state balance and transient verification, characterized in that The steps include: Step 1: Obtain model input data including load characteristics, construction sites, meteorological data, economic costs, and policy subsidies; Step 2: Establish models of each part of the wind-solar-storage microgrid under steady-state conditions, including power models of photovoltaic power generation equipment, wind turbines, and energy storage battery output under steady-state conditions; and perform power balance calculations to obtain several reasonable configuration schemes; Step 3: Taking the electricity cost as the optimization target, compare the several configuration schemes in step 2: Step 4: Use the electromechanical transient simulation method to verify the transient stability of each solution, and finally select the solution that can pass the transient stability verification and has the lowest cost per kilowatt-hour as the optimal configuration solution.

2. The method according to claim 1, characterized in that: In step 1, model input data including load characteristics, construction site, meteorological data, economic costs, and policy subsidies are obtained, including: the load size, type, important load power, and annual electricity consumption must be clarified; the size, longitude and latitude, and altitude of the construction site must be clarified; the local wind and light resources must be clarified; and the local electricity price and policy subsidies must be clarified.

3. The method according to claim 1, characterized in that: In the step 2, models of each part of the wind-solar-storage microgrid under steady state are established, including power models of photovoltaic power generation equipment, wind turbines, and energy storage battery output under steady state conditions; include ， Theoretical maximum output of photovoltaic power generation equipment P PV The calculation model is as follows: Where P PN is the output of the photovoltaic array under experimental conditions; k df is the photovoltaic derating factor; R T is the solar radiation in the current environment; R TS is the solar radiation in the test environment; b p is the temperature coefficient of power; T C is the current photovoltaic cell temperature; T CS is the photovoltaic cell temperature of the test environment; Theoretical maximum output of wind turbine generator set P w The calculation model is as follows: First calculate the wind speed v at the hub height of the wind turbine h : In the formula, v a is the wind speed at the anemometer height, in m / s; h h is the hub height of the wind turbine, in m; h a is the height of the anemometer, in meters; h0 is the surface roughness length, ln is the natural logarithm; the wind speed v at the hub height is determined according to the wind turbine output power curve given by the wind turbine manufacturer h The theoretical maximum output of a single wind turbine generator set is P w ; The energy storage charging and discharging model is as follows: when the power generated by photovoltaic and wind turbines is greater than the load power consumption, the energy storage battery can be charged; when the power generated by photovoltaic and wind turbines cannot meet the load demand, the energy storage battery discharges to meet the load demand. The rated power of the energy storage battery is P ES .

4. The method according to claim 1, characterized in that: In step 2, the power balance calculation is performed, including performing a power balance calculation with a step length of 1 hour and 8760 hours throughout the year, including a steady-state power balance calculation and a battery balance calculation, specifically including: The steady-state power balance calculation model is as follows: Where n pv is the number of photovoltaic power generation equipment, P pv，i is the output of photovoltaic power generation equipment, and the number of wind turbines is n w , P w，i is the output of the wind turbine, n ES is the capacity of the energy storage battery, P ES，i P is the energy storage charging and discharging power per kilowatt-hour, Load，i is the load power; The battery charge balance calculation model is as follows: In the formula, S ES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency, η ES,c For charging efficiency.

5. The method according to claim 1, characterized in that: In step 2, several reasonable configuration schemes are obtained, including obtaining several reasonable configuration schemes according to the following constraints: ① Photovoltaic and wind turbine output constraints: The output of photovoltaic power generation equipment P pv，i Not greater than the theoretical maximum output P PV , the output of wind turbine generator set P w，i Not greater than the theoretical maximum output P W ,Right now: 0≤P pv，i ≤P PV 0≤P w，i ≤P W ② Energy storage charging and discharging power constraint: The charging and discharging power of energy storage shall not exceed the rated power, so the energy storage charging / discharging power P ES，i The following constraints are met: 0≤P ES，i ≤P ES Where P Es is the energy storage rated power; ③ Energy storage battery power SOC constraint: The remaining battery capacity SOC S of the energy storage battery ES，i At the lower limit of remaining power control SOC min And the remaining power control upper limit SOC max Between, that is: SOC min ≤S ES，i ≤SOC max ④ Power supply reliability constraint: Set the uninterrupted operation time of important loads to t imp , in hours; That is, the capacity of the energy storage should not be less than the capacity of the important load at t imp The amount of electricity consumed, and the discharge power is not less than the power consumed by the important load, that is: Where W ES is the energy storage capacity, in kWh; P imp is the important load power, in kW; η ES,a is the discharge efficiency.

6. The method according to claim 1, characterized in that: In step 2, several reasonable configuration schemes are obtained, including configuration scheme X k ={n pv,k , n w,k , n ES，k }, k=1,2,…μ is calculated as follows: Where n pv P is the number of photovoltaic power generation equipment configured; pv，i is the output of photovoltaic power generation equipment, P PV is the theoretical maximum output of photovoltaic power generation equipment; n w is the number of wind turbine generator sets; P w，i is the output of the wind turbine, P W is the theoretical maximum output of the wind turbine; n ES is the capacity of the energy storage battery; P ES，i P is the charging / discharging power of the energy storage battery per kilowatt-hour; Load，i is the load power; S ES，i S is the remaining capacity of the battery after the i-th charge / discharge; ES，i-1 The remaining power of the battery before charging; P ES，i is the charge / discharge power; Δt c is the charging time; W ES is the battery capacity; Δt d is the discharge time; η ES,d is the discharge efficiency; P imp is the important load power; t imp The non-stop operation time for important loads; SOC min SOC is the lower limit of remaining power control. max is the upper limit of remaining power control, and μ is the number of configuration schemes.

7. The method according to claim 1, characterized in that: In step 3, the objective function cost of electricity (COE) is expressed as: In the formula, N is the life of the project, C0 is the initial investment cost, C om，i is the operation and maintenance cost, C repla，i is the replacement cost, I sub,i For policy subsidies, I rv (i) is the residual value in the i-th year, W load is the electricity consumed by the load in one year, and λ is the discount rate.

8. The method according to claim 1, characterized in that: In step 3, configure solution X k Substitute the calculation model of COE into the cost per kilowatt-hour in turn to calculate COE (X k ), and then sort them from low to high according to the electricity cost, and get a set of solutions: Y j ={n pv，j , n w,j , n ES，j }, j = 1, 2, ... μ, satisfying: COE (Y1) <COE(Y2)<COE(Y3)……COE(Y μ ).

9. The method according to claim 1, characterized in that: The specific content of step 4 is: Step 41: firstly, for the jth configuration scheme Y j Perform power flow calculation. When the following conditions are met, go to step 42. Otherwise, this solution is eliminated and step 41 is repeated for the j+1th configuration solution. Condition 1: whether the power flow calculation converges. Condition 2: whether the voltage of each node is within the allowable range. Condition 3: whether each component is overloaded. Step 42: Verify configuration scheme Y using electromechanical transient simulation method j Under the transient stability of large fluctuations in new energy, large-capacity impact load startup, and power grid failure, if the voltage and frequency can be kept stable, it means that the configuration scheme meets the transient stability requirements, and the output scheme Y j Otherwise, this solution is eliminated and the j+1th configuration solution is transferred to step 41, and finally the solution that can pass the transient stability check and has the lowest cost per kilowatt-hour is selected as the optimal configuration solution.

10. A microgrid energy storage optimization configuration system based on steady-state balance and transient verification, characterized in that: include, Data acquisition module, used to obtain model input data including load characteristics, construction sites, meteorological data, economic costs, and policy subsidies; The configuration scheme construction model is used to establish the models of each part of the wind-solar-storage microgrid under steady-state conditions, including the power model of photovoltaic power generation equipment, wind turbines and energy storage battery output under steady-state conditions; and perform power balance calculations to obtain several reasonable configuration schemes; The scheme comparison module is used to compare several configuration schemes output by the configuration scheme construction model, taking the cost per kilowatt-hour as the optimization target: and, The optimal configuration scheme output module is used to verify the transient stability of each scheme using the electromechanical transient simulation method, and finally select the scheme that can pass the transient stability verification and has the lowest cost per kilowatt-hour as the optimal configuration scheme.

Images