A combined primary and secondary energy storage optimization clearing method considering multiple backup modes

Abstract

This invention discloses a joint optimization clearing method for energy storage main and auxiliary systems considering multiple backup modes. First, an energy operation model is constructed, followed by a spinning reserve operation model. Then, with the goal of minimizing clearing costs, the energy operation model and the spinning reserve operation model are coupled to construct a joint optimization clearing model for energy storage main and auxiliary systems. Finally, the joint optimization clearing model is solved. This method can more comprehensively consider scenarios where energy storage provides backup, enhance the competitiveness of energy storage in the backup market, and provide more backup resources for the power grid.

Description

Technical Field

[0001] This invention belongs to the field of electricity trading spot market, specifically involving an energy storage main and auxiliary joint optimization clearing model that considers multiple backup modes in the electricity market environment. Background Technology

[0002] Energy storage possesses the ability to migrate energy in time and space, making it an excellent resource for peak shaving and valley filling. It also demonstrates superior performance in participating in a combined market primarily based on the energy market, supplemented by spinning reserve. The optimization and clearing method for energy storage's primary and secondary functions needs to focus on both the energy market and the reserve market aspects. Currently, models for energy storage participation in the energy market are relatively mature, often expressed using a six-equation model. However, models for energy storage participation in the reserve market need improvement. Energy storage can provide reserve in various ways, including: reduced charging power, reduced discharging power, increased charging power, increased discharging power, charging to discharging, and discharging to charging. Existing energy storage reserve models are mainly divided into two types: the first only considers two cases—increased charging power and increased discharging power; the second considers four cases—increased and decreased charging power, and increased and decreased discharging power. Most existing models neglect the reserve capacity provided by energy storage state switching. Furthermore, most existing models do not consider the limited energy capacity of energy storage. Continuous charging and discharging behavior and reserve call-up will change the state of charge of the energy storage, causing it to be too low or too high, making the original charging and discharging plan impossible to achieve. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this method provides a combined optimization and clearing approach for energy storage main and auxiliary systems that considers multiple backup modes.

[0004] This invention proposes a joint optimization and clearing model for energy storage considering multiple backup modes, comprising two parts: an energy operation model for energy storage and a spinning reserve operation model for energy storage. The energy operation model includes: charge / discharge power constraints, energy storage energy constraints, charge / discharge state constraints, an energy transfer function model, and a final value constraint. The backup constraint model includes: a multi-power backup constraint model and an energy backup constraint model.

[0005] Then, with the goal of minimizing energy and spinning reserve clearing costs, and using energy operation models and spinning reserve operation models as constraints, a joint optimization clearing model for energy storage as the primary and secondary energy storage components is formed. This model is then optimized and solved using Matlab and Cplex to obtain the energy storage primary and secondary energy storage clearing scheme. This invention mainly focuses on energy storage as the object and proposes a joint optimization clearing method for primary and secondary energy storage. This method can be combined with existing clearing methods to form a joint optimization clearing model for the electricity market that includes energy storage.

[0006] A method for optimizing and clearing energy storage systems that considers multiple backup modes, comprising the following steps:

[0007] Step (1): Construct an energy operation model;

[0008] The energy operation model includes: charging and discharging power constraints, energy storage constraints, charging and discharging state constraints, energy transfer function model, and final value constraints.

[0009] Step (2): Construct a rotating standby operation model;

[0010] The aforementioned spinning reserve operation model includes two parts: a multi-power reserve constraint model and an energy reserve constraint model.

[0011] Step (3): Construct a joint optimization and clearing model for energy storage main and auxiliary functions;

[0012] With the goal of minimizing clearing costs, the energy operation model and the spinning reserve operation model are coupled to construct a joint optimization clearing model for energy storage main and auxiliary functions;

[0013] Step (4): Solving the joint optimization clearing model;

[0014] The established energy storage main and auxiliary joint optimization and clearing model was optimized and solved using Matlab and Cplex to obtain the energy storage main and auxiliary clearing scheme.

[0015] Furthermore, the specific method for step (1) is as follows:

[0016] The energy storage operation model is modeled from two perspectives: power constraints and state of charge constraints. Power constraints include upper and lower limits for charging power and upper and lower limits for discharging power, as shown in equations (1) and (2), respectively. The energy state transition function and its constraints are shown in equations (3) and (4), respectively. In the modeling process, two variables are introduced to characterize the charging and discharging behavior of energy storage. Since charging and discharging of energy storage cannot occur simultaneously, they need to be constrained, as shown in equation (5). During the scheduling handover process, the scheduler tends to "reset" the state of energy storage before handing over the work. Therefore, there is a "reset" final value constraint for energy storage, as shown in equation (6).

[0017]

[0018] e t =e t-1 +η chr ·chr t -η dis ·dis t (3)

[0019] e MIN ≤e t ≤eMAX (4)

[0020]

[0021] e0 = e T (6)

[0022] In the formula, t represents the t-th hour. and chr t chr represents charging power and status respectively. MAX and chr MIN This represents the maximum and minimum charging power (where chr) MIN It can be 0), and dis t Dis represents the discharge power and state of the stored energy, respectively. MAX and dis MIN Indicates the maximum and minimum values ​​of discharge power (where dis) MIN (can be 0), e t As an energy state, e MAX and e MIN η represents the maximum and minimum values ​​of energy. chr and η dis These represent the charging and discharging efficiencies of energy storage, e0 and e, respectively. T These represent the initial state and the final state, respectively, and T represents the time to calculate the final value.

[0023] Furthermore, the specific method for step (2) is as follows:

[0024] The aforementioned spinning reserve operation model comprises two parts: a multi-power reserve constraint model and an energy reserve constraint model.

[0025] 1) Multiple power reserve constraint model:

[0026] Energy storage systems that provide spinning backup services mean that they participate in the energy market while also providing backup services.

[0027] Energy storage participating in the primary and secondary market will simultaneously participate in the energy market and the spinning reserve market for clearing. Therefore, when the spinning reserve is called upon, the energy storage itself is in a working state, and its reserve provision is achieved by changing the current state. The possible modes of providing reserve are shown in Table 1.

[0028] Table 110 Methods of Energy Storage Providing Spinning Reserve

[0029]

[0030]

[0031]

[0032] In the formula, and These represent positive and negative spinning reserves of energy storage, respectively. t' and chr t' This indicates the energy storage discharge and charging power parameters under backup demand.

[0033] The above 10 possibilities can be uniformly written as (17) and (18).

[0034]

[0035] 2) Energy reserve constraint model:

[0036] Traditional generators only consider power constraints when describing standby models. However, due to long-term participation in standby operation, the energy / state of charge of the energy storage will deviate from the expected value. In order to avoid the inability to provide clearing power or standby due to insufficient internal energy or rechargeable space, it is necessary to further consider its energy standby constraints.

[0037] After the power is called up for reserve, the energy deviation generated by the single step is shown in Equation (19) and Equation (20), respectively.

[0038]

[0039] In the formula, This indicates the energy deviation caused by negative spin-off reserve. This indicates the energy deviation caused by the positive rotation of the standby mode.

[0040] The market has set clear requirements for the sustainable operation capabilities of energy storage systems that participate in both the energy and backup markets. Therefore, to ensure that energy storage systems can continuously provide C-hour state of charge constraints, a multi-period positive and negative energy backup model is needed. and It can be written separately as:

[0041]

[0042] In the formula, e t and e t+c These represent the energy storage states at hour t and hour t+c, obtained according to the energy operation model. and These represent the energy deviation caused by negative and positive spinning reserves at hour t+m, respectively.

[0043] Furthermore, the specific method for step (3) is as follows:

[0044] From the perspective of clearing out the primary and secondary markets, energy storage participating in both the energy and spinning reserve markets simultaneously increases the cost of reserve clearing compared to participating only in the energy market. Therefore, its cost function is written as equation (23). In terms of constraints, it is necessary to consider both the constraints of the energy storage operation model, i.e., equations (1)-(6), and the constraints of the energy storage spinning reserve operation model, i.e., equations (17)-(22).

[0045]

[0046] Among them, C chr and C dis These are the charging and discharging costs of energy storage, C. + and C - These are the positive and negative spinning reserve costs for energy storage, respectively.

[0047] Furthermore, the specific method for step (4) is as follows;

[0048] For the model of joint optimization and clearing of energy storage main and auxiliary facilities, a solution method based on Matlab and Cplex is proposed. Matlab is used to compile the joint optimization and clearing model of hybrid energy storage main and auxiliary facilities, and the commercial solver Cplex is used to optimize and solve the model to obtain the energy storage main and auxiliary clearing scheme.

[0049] The beneficial effects of this invention are as follows:

[0050] This method can more comprehensively consider the scenario of energy storage providing backup, enhance the competitiveness of energy storage in the backup market, and provide more backup resources for the power grid. Attached Figure Description

[0051] Figure 1 A schematic diagram of the market-oriented model structure of energy storage main and auxiliary storage considering multiple backup modes in an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the test system structure according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the energy storage operation state structure according to an embodiment of the present invention;

[0054] Figure 4 This is a day-ahead positive and negative rotational reserve clearing scheme for energy storage according to an embodiment of the present invention. Detailed Implementation

[0055] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0056] Figure 1 A schematic diagram of the market-oriented model structure of energy storage main and auxiliary storage considering multiple backup modes in an embodiment of the present invention;

[0057] A method for optimizing and clearing energy storage systems that considers multiple backup modes, comprising the following steps:

[0058] Step (1) Constructing an energy operation model

[0059] From the perspective of energy storage participating in the electricity market, the energy storage operation model needs to be modeled from two angles: power constraints and state of charge constraints. The power constraints include upper and lower limits of charging power (Equation (1)) and upper and lower limits of discharging power (Equation (2), and the energy state transition function and its constraints are shown in Equations (3) and (4), respectively. In the modeling process, two variables are introduced to characterize the charging and discharging behavior of energy storage. However, the charging and discharging of energy storage cannot be carried out simultaneously, so they need to be constrained, as shown in Equation (5). During the dispatch handover process, the dispatcher tends to "reset" the state of energy storage before handing over the work. Therefore, there is a "reset" final value constraint for energy storage, as shown in Equation (6).

[0060]

[0061] e t =e t-1 +η chr ·chr t -η dis ·dis t (3)

[0062] e MIN ≤e t ≤e MAX (4)

[0063]

[0064] e0 = e T (6)

[0065] In the formula, t represents the t-th hour. and chr t chr represents charging power and status respectively. MAX and chr MIN This represents the maximum and minimum charging power (where chr) MIN It can be 0), and dis t Dis represents the discharge power and state of the stored energy, respectively. MAX and dis MIN Indicates the maximum and minimum values ​​of discharge power (where dis) MIN (can be 0), e t As an energy state, e MAX and e MIN η represents the maximum and minimum values ​​of energy. chr and η disThese represent the charging and discharging efficiencies of energy storage, e0 and e, respectively. T These represent the initial state and the final state, respectively, and T represents the time to calculate the final value.

[0066] Step (2): Construct a rotating standby operation model;

[0067] The aforementioned spinning reserve operation model comprises two parts: a multi-power reserve constraint model and an energy reserve constraint model.

[0068] 1) Multiple power reserve constraint model:

[0069] Energy storage systems that provide spinning backup services mean that they participate in the energy market while also providing backup services.

[0070] Energy storage participating in the primary and secondary market will simultaneously participate in the energy market and the spinning reserve market for clearing. Therefore, when the spinning reserve is called upon, the energy storage itself is in a working state, and its reserve provision is achieved by changing the current state. The possible modes of providing reserve are shown in Table 1.

[0071] Table 110 methods to provide spinning reserve for energy storage

[0072]

[0073]

[0074]

[0075] In the formula, and These represent positive and negative spinning reserves of energy storage, respectively. t' and chr t' This indicates the energy storage discharge and charging power parameters under backup demand.

[0076] The above 10 possibilities can be uniformly written as (17) and (18).

[0077]

[0078] 2) Energy reserve constraint model:

[0079] Traditional generators only consider power constraints when describing standby models. However, due to long-term participation in standby operation, the energy / state of charge of the energy storage will deviate from the expected value. In order to avoid the inability to provide clearing power or standby due to insufficient internal energy or rechargeable space, it is necessary to further consider its energy standby constraints.

[0080] After the power is called up for reserve, the energy deviation generated by the single step is shown in Equation (19) and Equation (20), respectively.

[0081]

[0082] In the formula, This indicates the energy deviation caused by negative spin-off reserve. This indicates the energy deviation caused by the positive rotation of the standby mode.

[0083] The market has set clear requirements for the sustainable operation capabilities of energy storage systems that participate in both the energy and backup markets. Therefore, to ensure that energy storage systems can continuously provide C-hour state of charge constraints, a multi-period positive and negative energy backup model is needed. and It can be written separately as:

[0084]

[0085] In the formula, e t and e t+c These represent the energy storage states at hour t and hour t+c, obtained according to the energy operation model. and These represent the energy deviation caused by negative and positive spinning reserves at hour t+m, respectively.

[0086] Step (3): Construct a joint optimization and clearing model for energy storage main and auxiliary functions;

[0087] From the perspective of clearing out the primary and secondary markets, energy storage participating in both the energy and spinning reserve markets simultaneously increases the cost of reserve clearing compared to participating only in the energy market. Therefore, its cost function can be written as (23). In terms of constraints, it is necessary to consider both the constraints of the energy storage operation model (1)-(6) and the constraints of the energy storage spinning reserve operation model (17)-(22).

[0088]

[0089] Among them, C chr and C dis These are the charging and discharging costs of energy storage, C. + and C - These are the positive and negative spinning reserve costs for energy storage, respectively.

[0090] Step (4): Solving the joint optimization clearing model;

[0091] For the model of joint optimization and clearing of energy storage main and auxiliary facilities, a solution method based on Matlab and Cplex is proposed. Matlab is used to compile the joint optimization and clearing model of hybrid energy storage main and auxiliary facilities, and the commercial solver Cplex is used to optimize and solve the model to obtain the energy storage main and auxiliary clearing scheme.

[0092] Case Analysis

[0093] The example analysis in this application is based on, for example, Figure 2 The system shown is a 6-node system. It includes three conventional generating units with capacities of 50MW, 110MW, and 140MW, and a renewable energy unit with a rated power of 50MW. The parameters of the energy storage system are shown in Table 2.

[0094] Table 2 System parameters of the energy storage system

[0095]

[0096] The energy storage operating status and its reserve clearing scheme, obtained by calculation using the commercial solver Cplex after Matlab programming, are as follows: Figure 3 and Figure 4 As shown. Among them, from Figure 3 As can be seen, the energy storage system underwent two charge-discharge operations in this round of cleanup. The first charge occurred from 1 to 4 o'clock, charging from 10MWh to a full energy state of 30MWh. As the load increased, discharge began gradually from 5 o'clock. The second charge started at 12 o'clock, when the output of new energy sources was relatively high, so the energy storage absorbed this part of the electricity. Discharge began from the evening peak at 17:00.

[0097] The energy storage market clearing plan for primary and secondary products is as follows: Figure 4 As shown, the total positive spin-around reserve is 73.24 MWh, and the total negative spin-around reserve is 67.9 MWh. Figure 4 It can be seen that at any given time, energy storage can simultaneously provide positive and negative spinning reserve. This is because the method proposed in this patent considers both the positive and negative spinning reserve capabilities of energy storage, greatly enhancing its competitiveness in both the primary and secondary power markets. It is particularly important to note that at time 4, since the energy storage is at full capacity, it cannot be charged, therefore its negative power reserve is 0.

Claims

1. A method for optimizing and clearing energy storage systems that considers multiple backup modes, characterized in that, The steps are as follows: Step (1): Construct an energy operation model; The energy operation model includes: charging and discharging power constraints, energy storage constraints, charging and discharging state constraints, energy transfer function model, and final value constraints. Step (2): Construct a rotating standby operation model; The aforementioned spinning reserve operation model includes two parts: a multi-power reserve constraint model and an energy reserve constraint model. Step (3): Construct a joint optimization and clearing model for energy storage main and auxiliary functions; With the goal of minimizing clearing costs, the energy operation model and the spinning reserve operation model are coupled to construct a joint optimization clearing model for energy storage main and auxiliary functions; Step (4): Solving the joint optimization clearing model; The established energy storage main and auxiliary joint optimization and clearing model was optimized and solved using Matlab and Cplex to obtain the energy storage main and auxiliary clearing scheme; The specific method for step (1) is as follows: The energy storage operation model is modeled from two perspectives: power constraints and state of charge constraints. The power constraints include upper and lower limits of charging power and upper and lower limits of discharging power, as shown in Equations (1) and (2), respectively. The energy state transition function and its constraints are shown in Equations (3) and (4), respectively. In the modeling process, two variables are introduced to characterize the charging and discharging behavior of energy storage. Since the charging and discharging of energy storage cannot be carried out simultaneously, they need to be constrained, as shown in Equation (5). In the scheduling handover process, the scheduler tends to "reset" the state of energy storage before handing over the work. Therefore, there is a "reset" final value constraint for energy storage, as shown in Equation (6). (1) (2) (3) (4) (5) (6) In the formula, t represents the t-th hour. and These represent charging power and status, respectively. and Indicates the maximum and minimum charging power. and These represent the discharge power and state of the stored energy, respectively. and Indicates the maximum and minimum values ​​of discharge power. In energy state, and Represents the maximum and minimum values ​​of energy. and These represent the charging and discharging efficiencies of energy storage, respectively. and These represent the initial state and the final state, respectively, and T represents the time to calculate the final value.

2. The energy storage main and auxiliary joint optimization and clearing method considering multiple backup modes according to claim 1, characterized in that, The specific method for step (2) is as follows: The aforementioned spinning reserve operation model comprises two parts: a multi-power reserve constraint model and an energy reserve constraint model. 1) Multiple power reserve constraint model: Energy storage systems that provide spinning backup services mean that they participate in the energy market and provide backup services at the same time. Energy storage participating in the primary and secondary market will simultaneously participate in the clearing of both the energy market and the spinning reserve market. Therefore, when spinning reserve is called upon, the energy storage itself is already in a working state, and its provision of reserve is achieved by changing the current state. The possible modes of providing reserve are as follows:

1. Current state "charging"; Demand state "charging increase"; Qualitative "negative rotation standby"; Calculation formula "(7)"; 2. Current status: "Charging"; Demand status: "Charging reduced"; Qualitative status: "Survival in positive rotation"; Calculation formula: "(8)"; 3. Current status: "Charging"; Required status: "Stationary"; Qualitative status: "Spinning forward for standby"; Calculation formula: "(9)"; 4. Current state: "Charging"; Demand state: "Discharging"; Qualitative state: "Side rotation standby"; Calculation formula: "(10)"; 5. Current state "Discharge"; Demand state "Discharge increase"; Qualitative "Positive rotation standby"; Calculation formula "(11)"; 6. Current state "discharge"; Demand state "discharge reduced"; Qualitative "negative rotation standby"; Calculation formula "(12)"; 7. Current state: "Discharge"; Required state: "Stationary"; Qualitative state: "Negative rotation standby"; Calculation formula: "(13)"; 8. Current state "discharging"; Demand state "charging"; Qualitative "negative rotation standby"; Calculation formula "(14)"; 9. Current state: "Still"; Demand state: "Charging"; Qualitative: "Negative rotation standby"; Calculation formula: "(15)"; 10. Current state: "Stationary"; Required state: "Discharge"; Qualitative state: "Straight-rotating standby"; Calculation formula: "(16)"; (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) In the formula, and These represent positive and negative spinning reserves for energy storage, respectively. and This indicates the energy storage discharge and charging power parameters under backup demand. The above may provide alternative patterns, uniform writing (17) and (18). (17) (18) 2) Energy Reserve Constraint Model: When describing the standby model, traditional generators only consider power constraints. However, due to long-term participation in standby operation, the energy / state of charge of the energy storage will deviate from the expected value. In order to avoid the inability to provide clearing power or standby due to insufficient internal energy or rechargeable space of the energy storage, it is necessary to further consider its energy standby constraints. After the power is called up for reserve, the energy deviation generated by a single step is shown in Equation (19) and Equation (20), respectively. (19) (20) In the formula, This indicates the energy deviation caused by negative spin-off reserve. This indicates the energy deviation caused by positive rotation for standby; The market has set clear requirements for the sustainable operation capabilities of energy storage that participates in both the energy and backup markets. Therefore, to ensure that energy storage needs to continuously provide a state of charge constraint of C hours, its multi-period positive and negative energy reserve model... and It can be written separately as: (21) (22) In the formula, and These represent the energy storage states at hour t and hour t+c, obtained according to the energy operation model. and These represent the energy deviation caused by negative and positive spinning reserves at hour t+m, respectively.

3. The energy storage main and auxiliary joint optimization and clearing method considering multiple backup modes according to claim 2, characterized in that, The specific method for step (3) is as follows: From the perspective of clearing out the primary and secondary markets, energy storage participating in both the energy and spinning reserve markets simultaneously increases the cost of reserve clearing compared to participating only in the energy market. Therefore, its cost function is written as equation (23). In terms of constraints, it is necessary to consider both the constraints of the energy storage operation model, i.e., equations (1)-(6), and the constraints of the energy storage spinning reserve operation model, i.e., equations (17)-(22). (23) in, and These are the charging and discharging costs of energy storage, respectively. and These are the positive and negative spinning reserve costs for energy storage, respectively.

4. The energy storage main and auxiliary joint optimization and clearing method considering multiple backup modes according to claim 3, characterized in that, The specific method for step (4) is as follows; For the model of joint optimization and clearing of energy storage main and auxiliary facilities, a solution method based on Matlab and Cplex is proposed. Matlab is used to compile the joint optimization and clearing model of hybrid energy storage main and auxiliary facilities, and the commercial solver Cplex is used to optimize and solve the model to obtain the energy storage main and auxiliary clearing scheme.

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