A joint planning method for transmission and storage considering wind-solar complementarity

Abstract

A transmission and storage joint planning method considering wind-solar complementarity includes inputting wind power data, photovoltaic power data, load data, and grid structure of typical scenarios in the planning target year; a transmission and storage joint planning model based on ensuring the reasonable investment and construction of wind farms and photovoltaic power stations as the planning target: considering the wind-solar complementarity characteristics, the operating characteristics of the energy storage system, and the line planning, with the goal of minimizing the equivalent annual investment cost of the line and energy storage, and the annual wind and photovoltaic abandonment costs, a transmission and storage joint planning model that improves the large-scale wind and photovoltaic acceptance capacity is established, and the location and power of the energy storage and the transmission network planning results are obtained; and three evaluation indicators, namely, wind-solar complementarity characteristics, power loss rate, and wind-photovoltaic-storage hybrid power system contribution rate, are proposed to evaluate the system. The present invention realizes coordinated planning between configuring energy storage and expanding lines, not only obtaining the optimal planning scheme for energy storage configuration and transmission network expansion, but also completely solving the wind and photovoltaic abandonment problems from the two aspects of wind-solar absorption and transmission congestion.

Description

Technical Field

[0001] The present invention relates to the technical field of a transmission and storage joint planning method, and in particular to a transmission and storage joint planning method combining energy storage with a transmission network to cope with wind and solar power consumption and transmission line congestion. Background Art

[0002] In recent years, wind power and photovoltaic power have been connected to the power grid on a large scale. However, the insufficient regulation capacity of thermal power units and the limitations of the network structure have resulted in the inability to solve the volatility and uncertainty of wind power and photovoltaic power [1-2], and will cause transmission lines to be blocked or overloaded. Therefore, it is necessary to plan the expansion of the transmission network and configure flexible energy storage to improve the absorption of wind and solar power.

[0003] There are many reasons for the abandonment of wind and solar power, and the main reasons include three aspects: 1) The intermittent and uncertain nature of new energy makes system planning more difficult and also affects the system's ability to adjust power. When the output of wind power and photovoltaic power generation increases rapidly, conventional units cannot reduce their output in time; or when the output of new energy is highly volatile, the system cannot fully meet the demand for new energy consumption in order to ensure safe and stable operation, which leads to the abandonment of wind and solar power; 2) The anti-peak regulation characteristics of wind power will greatly occupy the system's spare resources, increase the complexity of system scheduling and operation, and too few spare resources may not be able to suppress the fluctuation of new energy, causing safety and reliability problems in the system, thus causing the abandonment of wind and solar power; 3) The large-scale investment and construction of wind farms and photovoltaic power stations are generally far away from the load center, and their grid connection points may be located at the edge of the power grid, which is difficult to coordinate with the development of new energy. That is, due to the limitations of the system grid structure, the transmission capacity of the transmission line is insufficient, and line blocking may occur, making it difficult to send wind and solar power in time, thereby reducing the scope of wind and solar power consumption.

[0004] In order to improve the safety and reliability of power generation in wind farms and photovoltaic power stations, it is necessary to introduce flexible resources (energy storage). Energy storage access is conducive to improving the system's regulation capabilities. As a flexible resource, energy storage devices can reduce the capacity requirements of transmission lines and improve the flexibility of the system through their reasonable deployment. There are many existing planning methods for energy storage configuration, which are mainly divided into two categories: 1) configuring energy storage to increase the flexibility of the power supply side (i.e., peak-shaving capacity); 2) coordinated planning between energy storage and the transmission network. These two methods separate the power supply side from the grid side. Although they can solve the problem of wind and solar abandonment to a certain extent, they are likely to result in low utilization efficiency of energy storage, and the cost is too high, and the economy is not ideal.

[0005] Therefore, a transmission and storage joint planning method considering the complementarity of wind and solar power is proposed to solve the problems of wind and solar power abandonment from the two aspects of "being able to transmit" and "being able to absorb". Summary of the invention

[0006] The present invention provides a transmission and storage joint planning method taking into account wind-solar complementarity. Configuring a certain capacity of energy storage in a wind-solar complementary power generation system can not only effectively improve the consumption capacity of wind and solar power generation, but also improve the reliability and economy of the wind-solar complementary power generation system.

[0007] The technical solution adopted by the present invention is:

[0008] A transmission and storage joint planning method considering wind-solar complementarity is characterized by the following specific steps:

[0009] Input wind power data, photovoltaic power data, grid structure, information of each power source, and constraint boundary conditions for typical scenarios of wind and solar power consumption and transmission congestion in the planning target year;

[0010] A transmission and storage joint planning method based on ensuring the reasonable investment and construction of wind farms and photovoltaic power stations as the planning goal, specifically including considering the complementary characteristics of wind and solar power, the operating characteristics of the energy storage system and line planning, with the goal of minimizing the equivalent annual investment cost of lines and energy storage and the annual wind and solar abandonment costs, establishing a transmission and storage joint planning model that combines energy storage and transmission networks to improve the large-scale wind and solar acceptance capacity, and obtaining the location and power of energy storage and the transmission network planning results;

[0011] Based on the established transmission and storage joint planning model, three evaluation indicators are proposed to evaluate the system, namely, wind-solar complementary characteristics, power loss rate and wind-photovoltaic-storage hybrid power system contribution rate;

[0012] By utilizing the transmission and storage joint planning model that takes into account the complementarity of wind and solar, coordinated planning can be achieved between the configuration of energy storage and the expansion of transmission lines, which not only obtains the optimal planning scheme for energy storage configuration and transmission network expansion, but also completely solves the problems of wind and solar power abandonment from the two aspects of insufficient peak regulation and transmission congestion. At the same time, as the scale of the system continues to increase, the penetration rate of wind and solar energy continues to increase, energy storage technology continues to improve, and unit costs continue to decrease, the economic benefits of the transmission and storage joint planning that cooperates with the grid connection of wind and solar power become more and more significant, ultimately achieving the optimization of resource utilization and the maximization of social benefits.

[0013] Due to the phenomenon of wind and solar power abandonment caused by insufficient peak-shaving depth and transmission line congestion, it is necessary to build a transmission and storage joint planning model to deal with wind and solar power consumption and transmission congestion, and achieve coordinated optimization between configuring energy storage and expanding transmission lines, including:

[0014] In order to reduce the wind and solar power abandonment rate of the power grid, the optimization configuration model is established with the minimum sum of the annual wind power abandonment cost, solar power abandonment cost, equivalent annual investment cost of energy storage and equivalent annual investment cost of transmission lines as the objective function, that is:

[0015] min f=f ess +f wind +f pv +fline

[0016] In the formula, f ess is the energy storage investment cost; f wind is the annual wind curtailment cost; f pv is the annual abandoned light cost; f line is the transmission line cost;

[0017] The equivalent annual investment cost of energy storage includes two parts: variable power cost and fixed installation cost;

[0018]

[0019] c vess,k =k de (1+k oc +k mc +k dc )·(c p P ress,k +c e E ress,k )

[0020] Where: c vess,k and c fess,k are the variable cost and fixed cost of energy storage at node k; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; Ω ess P is a collection of available installation locations for energy storage; ress,k 、E ress,k is the continuous decision variable of the energy storage power and capacity to be configured at node k; de is the annual depreciation coefficient of energy storage; k oc , k mc , k dc are the energy storage operation, maintenance and disposal cost coefficients respectively; c p 、c e They are the unit power and unit capacity cost of energy storage respectively;

[0021] Annual wind and solar curtailment costs:

[0022]

[0023]

[0024] Where: Ω pv and Ω wind are the photovoltaic power station and wind farm sets respectively; Γ is the typical scene set; ψ is the scene time set; c wind is the unit wind power abandonment price, c pv is the unit power curtailment price; day s is the number of samples contained in scene s, P pv,j,t,sand P wind,j,t,s are the actual active power of PV power station or wind farm j in time period t and scenario s respectively; They are respectively the maximum actual active power of PV power station or wind farm j in time period t and scenario s.

[0025] Equivalent annual investment cost of transmission lines:

[0026]

[0027] Where: i is the discount rate; n is the economic useful life of the line; c line,ij is the investment cost of building a new line on branch ij; is the 0-1 decision variable for building the pth line on branch ij; Ω p is a set of lines to be selected;

[0028] The transmission and storage joint planning model considering wind-solar complementarity achieves coordinated optimization between configuring energy storage and expanding transmission lines, including the following constraints:

[0029] Node power balance constraints:

[0030]

[0031] Where: and are the branch active power column vectors of the existing line and the candidate line in the t period and s scenario respectively; A o and A p Represent the node-branch association matrix of the existing line and the line to be selected respectively; P wind,t,s , P pv,t,s and P gen,t,s are the active output column vectors of wind farm, photovoltaic power station and thermal power plant in time period t and scenario s respectively; P l,t,s and P ess,t,s They are the load demand column vector and energy storage charging power column vector in time period t and scenario s respectively.

[0032] Branch flow constraints:

[0033]

[0034] θ ref,t,s =0

[0035] Where: Ω o is a collection of lines; is the number of lines; b ij is the susceptance of branch ij; θ i,t,s and θ j,t,s are the voltage phase angles of nodes i and j in time period t and scenario s respectively; the voltage phase angle of the balance node θref,t,s Take 0. It is the column vector of branch active power transmitted by the existing line in time period t and scenario s.

[0036] Power limit constraints for branch transmission:

[0037]

[0038]

[0039] Where: is the maximum active power transmitted by branch ij. and They are the column vectors of branch active power transmitted by the existing line and the selected line in the time period t and the scenario s. is a 0-1 decision variable for building the pth line on branch ij; The number of lines.

[0040] The constraints also include:

[0041] Thermal power unit operation constraints:

[0042]

[0043]

[0044] Where: P gen,i,t,s is the active power of thermal power plant i in time period t and scenario s; and They are the upper and lower limits of active output of thermal power plant i respectively; and are the climbing rate and sliding rate of thermal power plant i respectively.

[0045] Wind power operation constraints:

[0046]

[0047] Photovoltaic power generation operation constraints:

[0048]

[0049] The constraints also include:

[0050] Energy storage operation constraints:

[0051] -P ress,k ≤P ess,k,t,s ≤P ress,k

[0052]

[0053] 0≤Eess,k,t,s ≤E ress,k

[0054] Where: P ress,k and E ress,k are the rated power and rated capacity of the kth energy storage respectively; E ess,k,t,s and P ess,k,t,s are the storage energy and discharge power of the kth energy storage in the t period and the s scenario respectively; and are the upper and lower limits of the rated power of the kth energy storage; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1;

[0055] E ess,k,1,s =E ess,k,t,s +P ess,k,1,s

[0056]

[0057] Where: E ess,k,1,s and E ess,k,t,s is the storage energy of the kth energy storage at the beginning and end of the sth scenario; E ess,k,t-1,s is the stored energy of the kth energy storage in the t-1 period in the sth scenario; P ess,k,1,s and P ess,k,t,s It is the charging and discharging power of the kth energy storage at the beginning and end of the sth scenario; T only represents the end moment and has no special meaning.

[0058]

[0059] Where: and are the upper and lower limits of the energy storage configuration number; ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; Ω ess A collection of possible installation locations for energy storage.

[0060] Spinning reserve constraints:

[0061]

[0062] Where: Ω gen ,Ω l ,Ω ess ,Ω pv and Ω wind They are the system thermal power plant set, load node set, energy storage optional installation site set, photovoltaic power station and wind farm set; P pv,j,t,s and P wind,j,t,s are the actual active power of PV power station or wind farm j in time period t and scenario s; P gen,i,t,sis the actual active power of thermal power plant i in time period t and scenario s; P l,m,t,s and R t,s They are the power demand and necessary backup demand of load node m in period t and scenario s respectively.

[0063] Based on the established transmission and storage joint planning model, three evaluation indicators are proposed to evaluate the system, namely, wind-solar complementary characteristics, power loss rate and contribution rate of wind-photovoltaic-storage hybrid power system, including:

[0064] The wind-solar complementary characteristic index is shown in formula 22:

[0065] The output power of the wind-solar-storage hybrid system relative to load fluctuation reflects the complementary characteristics of wind energy and solar energy, which is expressed by Equation 22.

[0066]

[0067] Where: D is the complementary characteristics of wind energy and solar energy, P wind,t is the wind power generation at time t, P pv,t is the photovoltaic power generation at time t, P l,t is the load power at time t, is the average power of the load. The smaller the index D is, the better the wind-solar-storage hybrid system can meet the load demand. The results of Case 4 show that the stronger the complementarity between wind energy and solar energy, the smaller the capacity of the energy storage system and the lower the cost.

[0068] The power loss rate indicator is shown in formula 23:

[0069] The power loss rate is used to indicate the ability of the wind-solar-storage hybrid system to meet load demand, as expressed by Equation 23:

[0070]

[0071] Where: f is the power loss rate; P wind,t , P pv,t , P l,t are wind power, photovoltaic power and load power at time t respectively; P ess,t is the power of the energy storage system at time t. The smaller f is, the more reliable the system power supply is;

[0072] The contribution rate of the wind-solar-storage hybrid system is shown in Formula 24:

[0073]

[0074] When P wind,t +P pv,t ≥P l,t , E t =P l,t

[0075] When P wind,t +P pv,t <P l,t , E t =P wind,t +P pv,t

[0076] When P l,t <P wind,t +P pv,t +P ess,t-1 ,P wind,t +P pv,t <P l,t , P ess,t-1 >0, E t =P l,t

[0077] When P l,t ≥P wind,t +P pv,t +P ess,t-1 , P ess,t-1 >0, E t =P wind,t +P pv,t +P ess,t-1

[0078] Where: R is the contribution rate of the wind, solar and storage system; E t is the power provided by the wind-solar-storage system to the load at time t. The larger R is, the less power is purchased from the grid; P wind,t , P pv,t , P l,t are wind power, photovoltaic power and load power at time t respectively; P ess,t-1 is the energy storage charging and discharging power at time t-1.

[0079] Taking advantage of the phenomenon of wind and solar power abandonment caused by insufficient peak-shaving depth and transmission line congestion, it is necessary to build a transmission and storage joint planning model that takes into account the complementarity of wind and solar power to cope with wind and solar power consumption and transmission congestion, so as to achieve coordinated optimization between configuring energy storage and expanding transmission lines, including:

[0080] Calculate the comprehensive cost of wind and solar power abandonment, transmission line investment cost, and energy storage investment cost, then modify the energy storage configuration and repeatedly calculate to obtain the optimal energy storage configuration under the current grid topology:

[0081] Correct the capacity of wind power and photovoltaic grid connection points, obtain a new grid topology through grid planning, and re-execute the steps of inputting wind power data, photovoltaic power data, information of each power source and current grid topology for the planning target year until the optimal solution for coordination of energy storage and transmission lines is obtained.

[0082] The present invention addresses the problems of insufficient peak regulation and transmission congestion caused by large-scale wind-solar grid connection, and proposes a transmission and storage joint planning method that considers wind-solar complementarity. The advantages are as follows:

[0083] 1. As a flexible resource, energy storage devices can reduce the capacity requirements of transmission lines and improve the flexibility of the system through their reasonable deployment. The power and capacity of energy storage devices can be flexibly selected and adjusted, which can better achieve "continuous" adjustment and improve the flexibility of the system.

[0084] 2. Consider the complementary characteristics of wind and solar power. This complementarity can be used to make up for the stability defects of individual wind power or photovoltaic power generation systems, improve system utilization efficiency, and reduce the impact on the power grid, so that the total output is consistent with the load size and change trend, thereby considering the joint transmission and storage planning of wind and solar power complementarity.

[0085] 3. Achieve coordinated planning between energy storage configuration and line expansion, so as to not only obtain the optimal planning scheme for energy storage configuration and transmission network expansion, but also completely solve the problems of wind and solar power abandonment from the two aspects of wind and solar power consumption and transmission congestion. At the same time, as the scale of the system continues to increase, the penetration rate of wind and solar energy continues to increase, the energy storage technology continues to improve, and the unit cost continues to decrease, the economic benefits of the joint planning of transmission and storage in conjunction with wind and solar power grid connection are becoming more and more significant, ultimately achieving the optimization of resource utilization and the maximization of social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 IEEE RTS-24 node system diagram provided for an embodiment of the present invention;

[0087] Figure 2 A typical wind power output scenario diagram provided by an embodiment of the present invention;

[0088] Figure 3 A typical photoelectric output scene diagram provided by an embodiment of the present invention;

[0089] Figure 4 A typical load scenario diagram provided by an embodiment of the present invention;

[0090] Figure 5 The calculation process of the combined planning of transportation and storage of the present invention;

[0091] Figure 6 A diagram showing changes in total power of energy storage configuration and total cost of wind and solar power abandonment provided in an embodiment of the present invention;

[0092] Figure 7 A comparison chart of wind power and photovoltaic access power and total wind and solar power abandonment costs for Case 1 and Case 2 provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0093] The following describes exemplary embodiments of the present invention in conjunction with the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention.

[0094] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0095] The following describes in detail the combined planning method for transmission and storage taking into account wind-solar complementarity to cope with the phenomenon of wind and solar power abandonment of the present invention using drawings and embodiments.

[0096] A transmission and storage joint planning method considering wind and solar complementarity, the specific steps are as follows:

[0097] (1) Input wind power data, photovoltaic power data, grid structure, and information on various power sources for typical scenarios in the target year.

[0098] For example, in a future planning year, all loads and power capacity of the IEEE RTS-24 node system are increased to three times the current value. On this basis, 7 new transmission corridors are added, with a total of 41 feasible expansion transmission corridors. Each transmission corridor can be equipped with up to 3 lines (including the original lines). In this section, the wind farm access point is 19 nodes, the photovoltaic power station access point is 4 nodes, and the 0-120MW*4h compressed air energy storage system is selected. The node system diagram is as follows Figure 1 As shown, the wind and solar load output is as follows Figure 2 , 3 , as shown in Figure 4.

[0099] (2) A transmission and storage joint planning model considering wind-solar complementarity to deal with insufficient peak load regulation and transmission congestion

[0100] Taking into account the complementary characteristics of wind and solar power, the operating characteristics of the energy storage system and line planning, with the goal of minimizing the equivalent annual investment cost of lines and energy storage and the annual cost of wind and solar power abandonment, a joint planning model of energy storage and transmission network is established to improve the large-scale wind and solar power acceptance capacity, and the location and power of the energy storage and the transmission network planning results are obtained.

[0101] (3) Objective function:

[0102] min f=f ess +f wind +f pv +fline (1)

[0103] In the formula, f ess is the energy storage investment cost; f wind is the annual wind curtailment cost; f pv is the annual abandoned light cost; f line is the transmission line cost.

[0104] The calculation formula for equivalent annual investment cost of transmission lines is:

[0105]

[0106] Where i is the discount rate; n is the economic useful life of the line; c line,ij is the investment cost of building a new line on branch ij; is the 0-1 decision variable for building the pth line on branch ij; Ω p is the line set to be selected.

[0107] Energy storage investment cost calculation formula (the annual investment cost of energy storage includes variable power cost and fixed installation cost):

[0108]

[0109] c vess,k =k de (1+k oc +k mc +k dc )·(c p P ress,k +c e E ress,k ) (3)

[0110] In the formula, c vess,k and c fess,k are the variable cost and fixed cost of energy storage at node k; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; Ω ess P is a collection of available installation locations for energy storage; ress,k 、E ress,k is the continuous decision variable of the energy storage power and capacity to be configured at node k; de is the annual depreciation coefficient of energy storage; k oc , k mc , k dc are the energy storage operation, maintenance and disposal cost coefficients respectively; c p 、c e They are the unit power and unit capacity cost of energy storage respectively.

[0111] The annual wind curtailment cost calculation formula is:

[0112]

[0113] In the formula, Ω wind is the wind farm set; Γ is the typical scenario set; ψ is the scenario time set; c wind is the unit wind power abandonment price; day s is the number of samples contained in scene s; P wind,j,t,s and are the actual active power and maximum power of wind farm j in time period t and scenario s respectively.

[0114] The annual abandoned light cost calculation formula is:

[0115]

[0116] In the formula, Ω pv For photovoltaic power station collection; c pv is the unit price of abandoned photovoltaic power; P pv,j,t,s , are the actual active power and maximum power of PV power station j in time period t and scenario s, respectively.

[0117] (4) Constraints:

[0118] Node power balance constraints:

[0119]

[0120] In the formula, and are the branch active power column vectors of the existing line and the candidate line in the t period and s scenario respectively; A o and A p Represent the node-branch association matrix of the existing line and the line to be selected respectively; P wind,t,s , P pv,t,s and P gen,t,s are the active output column vectors of wind farm, photovoltaic power station and thermal power plant in time period t and scenario s respectively; P l,t,s and P ess,t,s They are the load demand column vector and energy storage charging power column vector in time period t and scenario s respectively.

[0121] Branch flow constraints:

[0122]

[0123] θ ref,t,s =0

[0124] In the formula, Ω o is a collection of lines; is the number of lines; b ij is the susceptance of branch ij; θi,t,s and θ j,t,s are the voltage phase angles of nodes i and j in time period t and scenario s respectively; the voltage phase angle of the balance node θ ref,t,s Take 0.

[0125] Power limit constraints for branch transmission:

[0126]

[0127]

[0128] In the formula, is the maximum active power transmitted by branch ij. and They are the column vectors of branch active power transmitted by the existing line and the selected line in the time period t and the scenario s. is a 0-1 decision variable for building the pth line on branch ij; The number of lines.

[0129] Thermal power unit operation constraints:

[0130]

[0131]

[0132] Where, P gen,i,t,s is the active power of thermal power plant i in time period t and scenario s; and They are the upper and lower limits of active output of thermal power plant i respectively; and are the climbing and sliding rates of thermal power plant i respectively.

[0133] Wind power operation constraints:

[0134]

[0135] Where P wind,j,t,s and are the actual active power and maximum power of wind farm j in time period t and scenario s respectively.

[0136] Photovoltaic power generation operation constraints:

[0137]

[0138] Where P wind,j,t,s and are the actual active power and maximum power of wind farm j in time period t and scenario s respectively.

[0139] Energy storage operation constraints:

[0140] -Press,k ≤P ess,k,t,s ≤P ress,k

[0141]

[0142] 0≤E ess,k,t,s ≤E ress,k

[0143] E ess,k,1,s =E ess,k,T,s +P ess,k,1,s

[0144]

[0145]

[0146] Where, P ress,k and E ress,k are the rated power and rated capacity of the kth energy storage respectively; E ess,k,t,s and P ess,k,t,s are the storage energy and discharge power of the kth energy storage in the t period and the s scenario respectively; and are the upper and lower limits of the rated power of the kth energy storage; E ess,k,1,s and E ess,k,t,s is the storage energy of the kth energy storage at the beginning and end of the sth scenario; E ess,k,t-1,s is the stored energy of the kth energy storage in the t-1 period in the sth scenario; P ess,k,1,s and P ess,k,t,s is the charge and discharge power of the kth energy storage at the beginning and end of the sth scenario; and They are the upper and lower limits of the energy storage configuration number respectively.

[0147] Spinning reserve constraints:

[0148]

[0149] Where: Ω gen ,Ω l ,Ω ess ,Ω pv and Ω wind They are the system thermal power plant set, load node set, energy storage set to be configured, photovoltaic power station set and wind farm set; P pv,j,t,s and P wind,j,t,s are the actual active power of PV power station or wind farm j in time period t and scenario s; P gen,i,t,s is the actual active power of thermal power plant i in time period t and scenario s; P l,m,t,s and R t,sThey are the power demand and necessary backup demand of load node m in period t and scenario s respectively.

[0150] (5) Specific planning process

[0151] The first step is to input the wind power data, photovoltaic power data and load power data for the planning target year to give the initial grid structure. The second step is to make the thermal power units have the lowest output, consider the complementary output of wind and solar power, smooth the total output, and reduce the peak load pressure. The third step is to set the initial number of accessible nodes and expandable lines for wind farms, photovoltaic power stations, and energy storage. The fourth step is to consider the flow constraints and the operating constraints of the system power supply, and establish a joint transmission and storage planning model. The fifth step is to configure energy storage, calculate the comprehensive cost including transmission investment, energy storage investment and the cost of wind and solar power abandonment, and then correct the energy storage configuration. Correct the capacity of the grid connection point, obtain a new grid topology through grid planning, and repeat the first step to the fifth step until the optimal solution for the coordinated planning of energy storage and transmission lines is obtained. The specific optimization planning process is as follows: Figure 5 shown.

[0152] (6) The present invention designs four schemes: Case 1 considers the single planning of the transmission network under different scales of wind power or photovoltaic access; Case 2 considers the joint planning of energy storage and transmission network under different scales of wind power or photovoltaic access; Scheme 3 considers the single planning of the transmission network under different wind-solar ratios; Case 4 considers the joint planning of energy storage and transmission network under different wind-solar ratios.

[0153] (7) In order to further investigate the changing trend of total energy storage configuration power and wind and solar power abandonment costs when energy storage costs change, the energy storage cost coefficient γ is introduced into the energy storage variable cost function. ess ,Right now:

[0154]

[0155] Combined with the IEEE RTS-24 node system operation data, the above planning model and algorithm are used to obtain the relationship between the optimal configuration results of energy storage under different energy storage costs and the cost of wind and solar power abandonment, such as Figure 7 shown.

[0156] Wind power generation and photovoltaic power generation from 3000MW to 600MW, analyze the energy storage cost, line cost, wind abandonment cost, and solar abandonment cost, and finally compare the total cost, reflecting the advantages of joint planning of transmission and storage. The planning scheme is shown in Table 1 and Table 2. Comparison of wind power and photovoltaic access power and total wind and solar abandonment cost Figure 7 shown.

[0157] Table 1 Planning results of wind power generation cases 1 and 2 in IEEE RTS-24 bus system

[0158]

[0159] Table 2 Planning results of IEEE RTS-24 node system photovoltaic power generation cases 1 and 2

[0160]

[0161] The total of wind power and photovoltaic power is 5000MW, with the ratios of 4:1; 3:2; 2:3; 1:4 respectively. Compared with wind power generation or photovoltaic power generation alone, it can be seen that the complementary nature of wind and solar power will further reduce costs. The planning scheme is shown in Table 3.

[0162] Table 3 Planning results of wind-solar ratio cases 3 and 4 for IEEE RTS-24 node system

[0163]

[0164] The specific embodiments of the present invention have been described in detail. However, it is known to those skilled in the art that, as defined by the attached patent claims, other embodiments than the above disclosed embodiments of the present invention are equally within the scope of the present invention.

[0165] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary hardware platform. Based on such an understanding, all or part of the contribution of the technical solution of the present application to the background technology can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a magnetic disk, an optical disk, etc., including several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0166] The various embodiments of the present invention are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to in detail.

[0167] The present invention uses specific examples to illustrate the principles and implementation methods of the present application. The above examples are only used to help understand the method and core ideas of the application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A method for joint planning of transmission and storage considering wind-solar complementarity, characterized in that: The specific steps are as follows: Input wind power data, photovoltaic power data, grid structure, information of each power source, and constraint boundary conditions for typical scenarios of wind and solar power consumption and transmission congestion in the planning target year; A transmission and storage joint planning method based on ensuring the reasonable investment and construction of wind farms and photovoltaic power stations as the planning goal, specifically including considering the complementary characteristics of wind and solar power, the operating characteristics of the energy storage system and line planning, with the goal of minimizing the equivalent annual investment cost of lines and energy storage and the annual wind and solar abandonment costs, establishing a transmission and storage joint planning model that combines energy storage and transmission networks to improve the large-scale wind and solar acceptance capacity, and obtaining the location and power of energy storage and the transmission network planning results; Based on the established transmission and storage joint planning model, three evaluation indicators are proposed to evaluate the system, namely, wind-solar complementary characteristics, power loss rate and wind-photovoltaic-storage hybrid power system contribution rate; A transmission and storage joint planning model that takes into account the complementarity of wind and solar power is used to coordinate the planning between energy storage configuration and line expansion. Due to the phenomenon of wind and solar power abandonment caused by insufficient peak-shaving depth and transmission line congestion, it is necessary to build a transmission and storage joint planning model to deal with wind and solar power consumption and transmission congestion, and achieve coordinated optimization between configuring energy storage and expanding transmission lines, including: In order to reduce the wind and solar power abandonment rate of the power grid, the optimization configuration model is established with the minimum sum of the annual wind power abandonment cost, solar power abandonment cost, equivalent annual investment cost of energy storage and equivalent annual investment cost of transmission lines as the objective function, that is: minf=f ess +f wind +f pv +f line In the formula, f ess is the equivalent annual investment cost of energy storage; f wind is the annual wind curtailment cost; pv is the annual abandoned light cost; f line is the equivalent annual investment cost of the transmission line; The equivalent annual investment cost of energy storage includes two parts: variable power cost and fixed installation cost; c vess,k =k de (1+k oc +k mc +k dc )·(c p P ress,k +c e E ress,k ) Where: c vess,k and c fess,k are the variable power cost and fixed installation cost of energy storage at node k respectively; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; Ω ess P is a collection of available installation locations for energy storage; ress,k 、E ress,k is the continuous decision variable of the energy storage power and capacity to be configured at node k; de is the annual depreciation coefficient of energy storage; k oc , k mc , k dc are the energy storage operation, maintenance and disposal cost coefficients respectively; c p 、c e They are the unit power and unit capacity cost of energy storage respectively; Annual wind and solar curtailment costs: Where: Ω pv and Ω wind are the photovoltaic power station and wind farm sets respectively; Γ is the typical scene set; ψ is the scene time set; c wind is the unit wind power abandonment price, c pv is the unit power curtailment price; day s is the number of samples contained in scene s, P pv,j,t,s and P wind,j,t,s are the actual active power of PV power station or wind farm j in time period t and scenario s respectively; are the maximum actual active power of PV power station or wind farm j in time period t and scenario s respectively; Equivalent annual investment cost of transmission lines: Where: i is the discount rate; n is the economic useful life of the line; c line,ij is the investment cost of building a new line on branch ij; is the 0-1 decision variable for building the pth line on branch ij; Ω p is a set of lines to be selected; The transmission and storage joint planning model considering wind-solar complementarity achieves coordinated optimization between configuring energy storage and expanding transmission lines, including the following constraints: Node power balance constraints: Where: and are the branch active power column vectors of the existing line and the candidate line in the t period and s scenario respectively; A o and A p Represent the node-branch association matrix of the existing line and the line to be selected respectively; P wind,t,s , P pv,t,s and P gen,t,s are the active output column vectors of wind farm, photovoltaic power station and thermal power plant in time period t and scenario s respectively; P l,t,s and P ess,t,s are the load demand column vector and energy storage charging power column vector in the t period and s scenario respectively; Branch flow constraints: i ref,t,s =0 Where: Ω o is a collection of lines; is the number of lines; b ij is the susceptance of branch ij; θ i,t,s and θ j,t,s are the voltage phase angles of nodes i and j in time period t and scenario s respectively; the voltage phase angle of the balance node θ ref,t,s Take 0; is the column vector of branch active power transmitted by the existing line in time period t and scenario s; Power limit constraints for branch transmission: Where: is the maximum active power transmitted by branch ij; and are the branch active power column vectors transmitted by the existing line and the selected line in the t period and the s scenario respectively; is a 0-1 decision variable for building the pth line on branch ij; is the number of lines; The constraints also include: Thermal power unit operation constraints: Where: P gen,i,t,s is the active power of thermal power plant i in time period t and scenario s; and They are the upper and lower limits of active output of thermal power plant i respectively; and are the climbing rate and sliding rate of thermal power plant i respectively; Wind power operation constraints: Photovoltaic power generation operation constraints: Energy storage operation constraints: -P ress,k ≤P ess,k,t,s ≤P ress,k 0≤E ess,k,t,s ≤E ress,k Where: P ress,k and E ress,k are the rated power and rated capacity of the kth energy storage respectively; E ess,k,t,s and P ess,k,t,s are the storage energy and discharge power of the kth energy storage in the t period and the s scenario respectively; and are the upper and lower limits of the rated power of the kth energy storage; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; AND ess,k,1,s =And ess,k,t,s +P ess,k,1,s Where: E ess,k,1,s and E ess,k,t,s is the storage energy of the kth energy storage at the beginning and end of the sth scenario; E ess,k,t-1,s is the stored energy of the kth energy storage in the t-1 period in the sth scenario; P ess,k,1,s and P ess,k,t,s is the charge and discharge power of the kth energy storage at the beginning and end of the sth scenario; T only represents the end time and has no special meaning; Where: and are the upper and lower limits of the energy storage configuration number; x ess,k is the decision variable for whether to install energy storage at node k, which takes 0 or 1; Ω ess A collection of possible installation locations for energy storage; Spinning reserve constraints: Where: Ω gen ,Ω l ,Ω ess ,Ω pv and Ω wind They are the system thermal power plant set, load node set, energy storage optional installation site set, photovoltaic power station and wind farm set; P pv,j,t,s and P wind,j,t,s are the actual active power of PV power station or wind farm j in time period t and scenario s; P gen,i,t,s is the actual active power of thermal power plant i in time period t and scenario s; P l,m,t,s and R t,s They are the power demand and necessary backup demand of load node m in period t and scenario s respectively.

2. A method for joint planning of transmission and storage considering wind-solar complementarity as claimed in claim 1, characterized in that: Based on the established transmission and storage joint planning model, three evaluation indicators are proposed to evaluate the system, namely, wind-solar complementary characteristics, power loss rate and contribution rate of wind-photovoltaic-storage hybrid power system, including: The wind-solar complementary characteristic index is shown in formula 22: The output power of the wind-solar-storage hybrid system relative to load fluctuation reflects the complementary characteristics of wind energy and solar energy, which is expressed by Equation 22: Where: D is the complementary characteristics of wind energy and solar energy, P wind,t is the wind power generation at time t, P pv,t is the photovoltaic power generation at time t, P l,t is the load power at time t, is the average power of the load. The smaller the index D is, the better the wind-solar-storage hybrid system can meet the load demand; The power loss rate indicator is shown in formula 23: The power loss rate is used to indicate the ability of the wind-solar-storage hybrid system to meet load demand, which is expressed by equation 23: Where: f is the power loss rate; P wind,t , P pv,t , P l,t are wind power, photovoltaic power and load power at time t respectively; P ess,t is the power of the energy storage system at time t. The smaller f is, the more reliable the system power supply is; The contribution rate of the wind-solar-storage hybrid system is shown in Formula 24: When P wind,t +P pv,t ≥P l,t , E t =P l,t When P wind,t +P pv,t <P l,t , E t =P wind,t +P pv,t When P l,t <P wind,t +P pv,t +P ess,t-1 ,P wind,t +P pv,t <P l,t , P ess,t-1 >0, E t =P l,t When P l,t ≥P wind,t +P pv,t +P ess,t-1 , P ess,t-1 >0, E t =P wind,t +P pv,t +P ess,t-1 Where: R is the contribution rate of the wind, solar and storage system; E t is the power provided by the wind-solar-storage system to the load at time t. The larger R is, the less power is purchased from the grid; P wind,t , P pv,t , P l,t are wind power, photovoltaic power and load power at time t respectively; P ess,t-1 is the energy storage charging and discharging power at time t-1.

3. A method for joint planning of transmission and storage considering wind-solar complementarity as claimed in claim 1, characterized in that: Taking advantage of the phenomenon of wind and solar power abandonment caused by insufficient peak-shaving depth and transmission line congestion, it is necessary to build a transmission and storage joint planning model that takes into account the complementarity of wind and solar power to cope with wind and solar power consumption and transmission congestion, so as to achieve coordinated optimization between configuring energy storage and expanding transmission lines, including: Calculate the comprehensive cost of wind and solar power abandonment, transmission line investment cost, and energy storage investment cost, then modify the energy storage configuration and repeatedly calculate to obtain the optimal energy storage configuration under the current grid topology: Correct the capacity of wind power and photovoltaic grid connection points, obtain a new grid topology through grid planning, and re-execute the steps of inputting wind power data, photovoltaic power data, information of each power source and current grid topology for the planning target year until the optimal solution for coordination of energy storage and transmission lines is obtained.

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