Energy storage planning method considering comprehensive benefits of independent energy storage

Abstract

The invention discloses an energy storage planning method considering the comprehensive benefit of independent energy storage, and the method comprises the steps: building a section recognition index, and screening a key section; obtaining energy storage benefit cost data, and calculating independent energy storage comprehensive benefits; and establishing an energy storage planning model considering the independent energy storage comprehensive benefits according to the independent energy storage comprehensive benefits and consideration of key section power flow constraints. According to the invention, the technical performance of independent energy storage can be fully considered, multiple applications of energy storage in an electric energy market, an auxiliary service market and a capacity leasing market are expanded, and the comprehensive benefits of independent energy storage are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage planning models, and more specifically, to an energy storage planning method that takes into account the comprehensive benefits of independent energy storage. Background Art

[0002] As the proportion of clean energy in the grid energy structure continues to increase, clean energy power systems based on wind power and photovoltaic power generation are gradually replacing high-carbon emission power systems based on traditional fossil fuel power generation. In order to cope with the volatility of large-scale clean energy access to the grid system, the system needs to reserve a certain amount of spare capacity, and energy storage, with its advantages of both charging and discharging characteristics, rapid response and flexible configuration, is an important resource for system spare capacity.

[0003] At present, the main application scenarios of energy storage at home and abroad include distributed power supply side, user side and grid side, presenting various forms such as independent energy storage, joint operation with distributed power generation, microgrid, etc. With the continuous deepening of power market construction, energy storage has gradually participated in power market transactions as an independent entity. However, for areas with small market compensation for power peak-valley price difference and frequency regulation auxiliary service, the market operation value of energy storage may be limited, making it difficult to achieve the expected profit target, and in the long-term planning of energy storage, there is a lack of consideration for alleviating network congestion effects and dynamic updating of grid structure. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an energy storage planning method that takes into account the comprehensive benefits of independent energy storage, fully considers the technical performance of independent energy storage, expands the diversified application of energy storage in the electric energy market, ancillary service market and capacity leasing market, and improves the comprehensive benefits of independent energy storage.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for energy storage planning considering the comprehensive benefits of independent energy storage includes the following steps: Establish section identification indicators and screen key sections; obtain energy storage benefit cost data and calculate the comprehensive benefits of independent energy storage; establish an energy storage planning model that considers the comprehensive benefits of independent energy storage based on the comprehensive benefits of independent energy storage and the flow constraints of key sections; Among them, the formula for calculating the comprehensive benefits of independent energy storage is:

[0006] The energy storage planning model is:

[0007] In the formula, Y and T are the total number of typical days selected in a year and the set of typical day scheduling time periods respectively; is the operating cost of the generator set.

[0008] Furthermore, the steps of establishing section identification indicators and screening key sections are as follows: Establish the power transmission distribution factor and key section identification index of key section identification index; judge the line with the largest disconnection index according to the key section identification index value of each transmission line in the power grid, and search for the line that is closely connected to the current disconnected line branch; check whether the line set meets the cut set characteristics, restore the non-cut set transmission lines to form a new partition, and the connecting lines between the partitions constitute the initial transmission section; calculate the transmission capacity margin of each transmission section, and select the transmission section with heavy section flow and transmission capacity margin lower than the minimum safety margin as the key section; screen the identified key sections, and establish key section flow constraints.

[0009] The establishment of an energy storage planning model that takes into account the comprehensive benefits of independent energy storage specifically includes: establishing an objective function of the independent energy storage planning model to calculate the operating cost of the generator set; establishing constraints, which include generator set operating constraints, power flow constraints, independent energy storage system constraints, and node power balance constraints.

[0010] Technical effects and advantages of an energy storage planning method considering the comprehensive benefits of independent energy storage according to the present invention: The present invention comprehensively considers the characteristics of key sections, the grid topology, the reliability and criticality of the lines, and proposes key section identification indicators. By using the proposed key section identification indicators, weak transmission channels in the network can be accurately obtained. The present invention selects the connection area of ​​the key section as the configuration location of the independent energy storage, and dynamically updates it year by year to clarify the optimal location area in the long-term planning of independent energy storage. Based on the identified key sections, energy storage planning is carried out in its connection area, and the energy storage site selection is adjusted as the key sections are dynamically updated, which can effectively alleviate network congestion. The present invention establishes an energy storage planning model that takes into account the comprehensive benefits of independent energy storage, expands the diversified applications of energy storage in the power market, and realizes the improvement of the comprehensive benefits of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the key section identification process of the present invention; Figure 2 Schematic diagram of the stochastic planning process of independent energy storage considering dynamic update of key sections; Figure 3 This is a schematic diagram of the improved IEEE RTS-79 system grid partitioning results; Figure 4 This is a schematic diagram of wind power output and load demand curve; Figure 5 This is a schematic diagram of the demand curve for leasing power at a wind farm; Figure 6 Schematic diagram of frequency modulation power demand curve. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product.

[0014] A storage planning model considering the comprehensive benefits of independent energy storage, see Figure 1 , comprehensively considering the characteristics of key sections, power grid topology, reliability and criticality of lines, propose key section identification indicators and identify key sections; then refer to Figure 2 , 3 , screen the identified key sections and establish the key section flow constraints; then, establish an energy storage planning model that considers the comprehensive benefits of independent energy storage, expand the diversified application of energy storage in the power market, and achieve the improvement of the comprehensive benefits of the energy storage system. Specifically, it is carried out in the following steps: Step 1: Comprehensively consider the characteristics of key sections, grid topology, reliability and criticality of lines, propose key section identification indicators and identify key sections.

[0015] Step 1.1: Establish the power transmission distribution factor of key section identification index: The power transfer distribution factor is defined as the change in the injected active power of the load at node b when the active power injection of other nodes remains unchanged. , the change in active power injected by the generator at node a is When, line It has been produced The active power change, at this time the power transfer distribution factor is expressed as and The ratio can be expressed by formula (1); (1) In formula (1), is the mutual reactance between the i-th row and a-th column of the node reactance matrix; For line lij reactance.

[0016] Under the assumption of DC power flow model, the power transfer distribution factor is only related to the grid topology and node susceptance, ignoring the impact of node injection power on line criticality.

[0017] Step 1.2: Establish key section identification indicators , comprehensively considering the node injection power, grid topology and line reliability, as shown in formula (2): (2) In formula (2), and They are respectively the set of power generation nodes and the set of load nodes; is the load factor of line l, and heavily loaded lines are more susceptible to power flow transfer; and They are the active power of the generation node and the active power of the load node respectively; Used to quantify the importance of a line to power transfer at a generator node or load node.

[0018] Step 1.3, calculate the key section identification index value of each transmission line of the power grid, disconnect the line with the largest index, and search for the line that is more closely connected to the branch of the currently disconnected line; Step 1.4, check whether the line set meets the cut set characteristics, restore the non-cut set transmission lines to form new partitions, and the connecting lines between the partitions constitute the initial transmission section; Step 1.5: Calculate the transmission capacity margin of each transmission section using formula (3), and select the transmission section with heavy section flow and transmission capacity margin lower than the minimum safety margin as the key section. In this embodiment, the minimum transmission margin of the key section is set to 20%.

[0019] (3) In formula (3), is the transmission capacity margin of section m; is the rated transmission power of section m; is the transmission power of section m.

[0020] Step 1.6, screen the identified key sections and establish the key section flow constraints; Step 1.6.1: Define the line The flow load fraction , as shown in formula (4).

[0021] (4) (5) In formula (5), For line ij The load factor, is the set of all lines; Based on each moment in a typical day, the flow load fractions of all lines are calculated and summed up, and the selected The biggest moment is to screen the key sections.

[0022] Step 1.6.2, select the transmission area and receiving area of ​​the key section as the planning location of the independent energy storage, and establish the key section power flow constraint as shown in formula (6); (6) Formula (6) is the flow constraint of the key section. and Key sections Tidal lower and upper limits; For the cross section The planning period is set to 5 years in this embodiment. For the convenience of analysis, the historical load demand and wind power output of 3 typical days are selected from each quarter of the year, a total of 12 typical days are analyzed, and the load demand increases by 3% each year thereafter. Figure 4 .

[0023] Step 2: Calculate the comprehensive benefits of independent energy storage; Step 2.1, calculate the cost of the independent energy storage system, the formula is as shown; (7) In formula (7) , The daily investment cost and life loss cost of independent energy storage, and They are the frequency regulation market income and peak-valley arbitrage income of energy storage; Independent energy storage operators , , , , The formulas are as follows (8)-(15).

[0024] Calculate the daily cost of energy storage investment; (8) Calculate life loss costs; (9) Calculate the market benefits of energy storage and frequency regulation; (10) Calculate the peak-valley arbitrage benefits of energy storage; (11) Calculate energy storage leasing revenue; (12) Calculate penalty costs for not meeting frequency regulation and leasing requirements with energy storage; (13) (14) (15) In formula (8): B is the AC busbar set, is the independent energy storage set of bus node i; r is the discount rate, Tyear is the economic service life of the energy storage device; and are the unit capacity investment cost and configuration capacity of energy storage u respectively.

[0025] In formula (9): The life loss cost per unit charge and discharge of energy storage; and They represent the charging and discharging power of energy storage u used for leasing at time t respectively; and They represent the power purchased and sold by energy storage u to the grid at time t respectively; and They respectively represent the charging and discharging power of energy storage u participating in frequency modulation at time t; For the time interval.

[0026] In formula (10): is the unit capacity price of energy storage u at time t; is the price per mileage of energy storage u at time t; is the frequency modulation mileage coefficient, which is the hourly historical average of the frequency modulation mileage calculated from the historical AGC signal.

[0027] In formula (11): and They are respectively the time-of-use electricity sales and purchase prices of the power grid.

[0028] In formula (12): W is the wind farm set; , are the unit prices for charging and discharging set by the independent energy storage operator for wind farm w at time t; , They are respectively the charging and discharging power required by wind farm w for independent energy storage at time t.

[0029] In formula (13): The penalty cost coefficient for energy storage failing to meet leasing demand and frequency regulation demand; and They are the deviations of the leasing demand and frequency regulation demand that are not met by energy storage at time t.

[0030] In formula (14), and They are respectively the charging deviation and discharging deviation of energy storage for wind farm leasing demand In formula (15), and They are respectively the charging deviation and discharging deviation of energy storage for frequency regulation demand; and They are the frequency regulation, charging and discharging power demands of the ancillary service market respectively.

[0031] Step 3: Establish an energy storage planning model that considers the comprehensive benefits of independent energy storage; Step 3.1, establish the objective function of the independent energy storage planning model; The present invention takes the planned investment cost of energy storage and the minimum total operating cost of the entire system as the optimization goal, and proposes an energy storage planning model that considers the comprehensive benefits of independent energy storage.

[0032] The present invention takes into account the overall interests of power plants and independent energy storage operators and establishes the objective function of the independent energy storage planning model, as shown in formula (16).

[0033] (16) Where: Y and T are the total number of typical days selected in a year and the set of typical day scheduling time periods respectively; is the operating cost of the generator set; , They are the daily investment cost and life loss cost of independent energy storage. and They are the frequency regulation market income and peak-valley arbitrage income of energy storage; Lease costs paid to independent energy storage operators for wind farms. The formula is shown in (17). The relevant important parameters of the energy storage configuration of this embodiment are shown in Table 1, and the wind farm leasing requirements and system frequency regulation power requirements are shown in Figure 5 and Figure 6 .

[0034] Table 1 Key parameters of independent energy storage

[0035] Calculate the operating cost of the generator set: (17) In formula (17): G is the set of generator sets; , and are the power generation cost coefficients of generator set g respectively; is the active output of generator set g at time t; is a 0-1 variable indicating the start / stop status of the generator set g at time t; and are respectively the startup cost and shutdown cost of generator set g at time t; and The upward reserve and downward reserve capacity of generator set g at time t, It is the standby cost coefficient fee.

[0036] Step 3.2, establish the operating constraints of the generator set; Active output constraints: (18) In formula (18), and They are the lower and upper bounds of the unit g output respectively.

[0037] Hill climbing constraints: (19) In formula (19), and They are the upward and downward climbing rate limits of unit g respectively.

[0038] Spare capacity constraints: (20) In formula (20), and They are respectively the maximum upward and downward reserves that unit g can provide.

[0039] Minimum start and stop time constraints: (twenty one) In formula (21), and are the time that unit g has been in the on state and in the off state at time t-1, respectively. and are the minimum start-up time and minimum shutdown time of unit g respectively.

[0040] Start-stop fee constraints: (twenty two) (twenty three) In formula (22), and They represent the single startup cost and shutdown cost of unit g respectively.

[0041] Step 3.3, establish power flow constraints; Branch flow constraints: (twenty four) (25) In formula (24), is the power flow of line ij at time t, is the admittance of line ij, is the voltage phase angle of node i at time t, is the transmission capacity of line ij. Equation (24) is the node voltage phase angle constraint, where and are the upper and lower limits of the voltage phase angle respectively.

[0042] Key section flow constraints: (26) Step 3.4, establish independent energy storage system constraints; Constraints on independent energy storage investment and construction: (27) In formula (27): Set a cap on the amount of independent energy storage; A binary variable indicating whether independent energy storage u is configured; and are the upper and lower capacity limits configured for energy storage u respectively.

[0043] Power constraints for independent energy storage participating in frequency regulation: (28) In formula (28): and Binary variables representing the charging and discharging states of the energy storage system.

[0044] Independent energy storage charging and discharging power constraints: (29) (30) In formula (29): and are the charging and discharging power of energy storage u participating in peak-valley arbitrage at time t, and are the minimum and maximum charging power of energy storage u, and are the minimum and maximum discharge powers of energy storage u respectively; (31) (32) In formula (31): and are the total charging and discharging power of energy storage u at time t respectively.

[0045] Independent energy storage capacity constraints: (33) (34) In formula (33): is the capacity of energy storage u at time t; and are the charging and discharging efficiencies of energy storage u, respectively; and are the lower limit coefficient and upper limit coefficient of the remaining capacity of the energy storage system respectively; In order to ensure the safety and sustainability of the independent energy storage system, the charge after the energy storage reserved the rental charging and discharging power is restricted: (35) (36) In formula (35), is the capacity of energy storage u participating in peak-valley arbitrage at time t.

[0046] Wind farm rental energy storage charging and discharging power constraints: (37) (38) Formula (37) is the charging and discharging power limit constraint of the wind farm renting energy storage, where , They are the lower and upper limits of independent energy storage charging for wind farms. , are the lower and upper limits of wind farms using independent energy storage discharge, and are binary variables representing the charging and discharging status of the rented energy storage in the wind farm. Formula (37) constrains the total charging and discharging power demand of all wind farms to be equal to the total charging and discharging power of all independent energy storage devices for leasing.

[0047] Step 3.5, establish node power balance constraints; (39) In formula (39): , , , and They are the generator set set, wind farm set, independent energy storage set, branch set and load set connected to bus node i respectively; is the power of wind farm w at time t; is the power of load d at time t.

[0048] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0049] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0050] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0051] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for energy storage planning considering the comprehensive benefits of independent energy storage, characterized in that: The steps include: Establish section identification indicators and screen key sections; Obtain energy storage benefit cost data and calculate the comprehensive benefits of independent energy storage; According to the comprehensive benefits of independent energy storage and the constraints of the flow of key sections, an energy storage planning model considering the comprehensive benefits of independent energy storage is established; Among them, the formula for calculating the comprehensive benefits of independent energy storage is: The energy storage planning model is: In the formula, Y and T are the total number of typical days selected in a year and the set of typical day scheduling time periods respectively; is the operating cost of the generator set.

2. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 1 is characterized in that: The steps of establishing section identification index and screening key sections are as follows: Establish the power transmission distribution factor and key section identification index for key section identification; According to the key section identification index values ​​of each transmission line of the power grid, the line with the largest disconnection index is determined, and the line with a close electrical connection with the branch of the currently disconnected line is searched; Check whether the line set meets the cut set characteristics, restore the non-cut set transmission lines to form new partitions, and the connecting lines between the partitions constitute the initial transmission section; Calculate the transmission capacity margin of each transmission section, and select the transmission section with heavy section flow and transmission capacity margin lower than the minimum safety margin as the key section; The identified key sections are screened and the flow constraints of the key sections are established.

3. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 2 is characterized in that: The power transmission distribution factor of the key section identification indicator is expressed as: In the formula, is the mutual reactance between the i-th row and a-th column of the node reactance matrix; is the mutual reactance between the i-th row and b-th column of the node reactance matrix The mutual reactance between the jth row and ath column of the node reactance matrix is, is the mutual reactance between the jth row and bth column of the node reactance matrix; For line The reactance, is the change in active power injected by the generator at node a, For line The amount of active power change produced on The key section identification index is expressed as follows: In the formula, It is the key section identification index. and They are respectively the set of power generation nodes and the set of load nodes; is the load factor of line l, and heavily loaded lines are more susceptible to power flow transfer; and They are the active power of the generation node and the active power of the load node respectively; It is used to quantify the importance of a line to the power transfer of a generator node or a load node.

4. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 3 is characterized in that: The transmission capacity margin of the transmission section is expressed as follows: 。 In the formula, is the transmission capacity margin of section m; is the rated transmission power of section m; is the transmission power of section m.

5. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 3 is characterized in that: The establishment of an energy storage planning model that considers the comprehensive benefits of independent energy storage specifically includes: Establish the objective function of the independent energy storage planning model and calculate the operating cost of the generator set; Establishing constraint conditions, wherein the constraint conditions include generator set operation constraints, power flow constraints, independent energy storage system constraints, and node power balance constraints; Among them, the operating cost of the generator set is calculated as follows: Where: is the operating cost of the generator set, G is the set of generator sets; , and are the power generation cost coefficients of generator set g respectively; is the active output of generator set g at time t; is a 0-1 variable indicating the start / stop status of the generator set g at time t; and are respectively the startup cost and shutdown cost of generator set g at time t; and The upward reserve and downward reserve capacity of generator set g at time t, It is the standby cost coefficient fee.

6. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 5 is characterized in that: The specific steps of establishing the power flow constraint are as follows: Defining a route The flow load fraction , based on each moment in a typical day, calculate the flow load fractions of all lines and sum them up, and select The biggest moment is to screen the key sections; Select the transmission and receiving areas of key sections as the planning locations for independent energy storage, and establish the power flow constraints of key sections; Among them, define the line The flow load fraction , such as the formula; In the formula, For line ij The load factor, is the set of all lines; The formula for the flow constraint of the key section is as follows: In the formula, and Key sections Tidal lower and upper limits; For the cross section A collection of lines.

7. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 5 is characterized in that: The generator set operation constraints specifically include: Active output constraints: In the formula, and They are the lower and upper bounds of the unit g output respectively. Hill climbing constraints: In the formula, and They are the upward and downward climbing rate limits of unit g respectively. Spare capacity constraints: In the formula, and They are respectively the maximum upward and downward reserves that unit g can provide. Minimum start and stop time constraints: In the formula, and are the time that unit g has been in the on state and in the off state at time t-1, respectively. and are the minimum start-up time and minimum shutdown time of unit g respectively. Start-stop fee constraints: In the formula, and They represent the single startup cost and shutdown cost of unit g respectively.

8. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 5 is characterized in that: The independent energy storage system constraints include: Independent energy storage investment and construction constraints: Where: Set a cap on the amount of independent energy storage; A binary variable indicating whether independent energy storage u is configured; and are the upper and lower capacity limits configured for energy storage u respectively. Power constraints for independent energy storage participating in frequency regulation: Where: and are binary variables representing the charging and discharging states of the energy storage system, and They represent the charging and discharging power of energy storage u participating in frequency modulation at time t, and They are respectively the charging deviation and discharging deviation of energy storage for wind farm leasing demand, and They are respectively the charging deviation and discharging deviation of energy storage for frequency regulation requirements, and They are the frequency regulation charging and discharging power demand of the ancillary service market; Independent energy storage charging and discharging power constraints: Where: and are the charging and discharging power of energy storage u participating in peak-valley arbitrage at time t, and are the minimum and maximum charging power of energy storage u, and are the minimum and maximum discharge powers of energy storage u respectively; Indicates a short period of time. Where: and are the total charging and discharging power of energy storage u at time t, and They represent the power purchased and sold by energy storage u to the grid at time t respectively; Independent energy storage capacity constraints: Where: is the capacity of energy storage u at time t; is the capacity of energy storage u at time t+1; and are the charging and discharging efficiencies of energy storage u, respectively; and are the lower limit coefficient and upper limit coefficient of the remaining capacity of the energy storage system respectively; Charge Constraints: In the formula, The capacity of energy storage u participating in peak-valley arbitrage at time t; Wind farm rental energy storage charging and discharging power constraints: In the formula, , They are the lower and upper limits of independent energy storage charging for wind farms. , are the lower and upper limits of wind farms using independent energy storage discharge, and Binary variables representing the charging and discharging status of the rented energy storage of the wind farm.

9. The energy storage planning method considering the comprehensive benefits of independent energy storage according to claim 5 is characterized in that: The node power balance constraint is established: Where: , , , and They are the generator set set, wind farm set, independent energy storage set, branch set and load set connected to bus node i respectively; is the power of wind farm w at time t; is the power of load d at time t.

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