Flexible interconnection power distribution network energy storage optimal configuration method and device

Abstract

The invention provides a flexible interconnected power distribution network energy storage optimal configuration method and device, and belongs to the field of power systems. The method comprises the following steps: establishing a target function by taking the minimum sum of the investment cost of an energy storage system and the operation and maintenance cost of the flexible interconnected power distribution network as a target; according to the energy storage parameters of the energy storage system, establishing energy storage system constraint conditions of the objective function; according to the energy storage parameter, an inverter parameter of a distributed power generation inverter in the flexible interconnected power distribution network and a net load parameter of the flexible interconnected power distribution network, establishing a flexibility constraint condition of the target function; establishing a configuration constraint condition of the target function according to the node parameters of the flexible interconnected power distribution network; and based on the energy storage system constraint condition, the flexibility constraint condition and the configuration constraint condition, solving the objective function to obtain a flexible interconnection power distribution network energy storage optimization configuration scheme. The flexibility of the power distribution network can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and device for optimizing energy storage configuration in a flexible interconnected distribution network. Background Art

[0002] Distributed energy continues to be connected to distribution networks in large quantities around the world. The large-scale access of distributed energy has brought problems such as transformer overload and line congestion to distribution networks. These problems can be effectively alleviated by configuring energy storage systems (ESS).

[0003] In the related art, when configuring the energy storage system, the energy storage configuration is mainly planned with the goal of minimizing the investment, operation and maintenance and loss costs of the ESS, wherein the uncertainty of distributed energy and load is mainly handled by scenario-based stochastic programming or robust optimization. However, the inventors have found that with the increase in the amount of variable renewable energy access, it is difficult to further optimize the energy storage configuration by configuring the energy storage according to the above-mentioned stochastic programming and robust optimization, and the distribution network's ability to cope with uncertainty and supply-demand imbalance is still insufficient. Summary of the invention

[0004] The embodiments of the present invention provide a method and device for optimizing the configuration of energy storage in a flexible interconnected distribution network, so as to optimize the configuration of an energy storage system in the distribution network, improve the flexibility of the distribution network, and enhance the ability of the distribution network to balance supply and demand.

[0005] In a first aspect, an embodiment of the present invention provides a method for optimizing energy storage configuration in a flexible interconnected distribution network, comprising:

[0006] The objective function is established with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network.

[0007] Establishing energy storage system constraints of the objective function according to energy storage parameters of the energy storage system;

[0008] Establishing flexibility constraints of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverter in the flexible interconnected distribution network, and the net load parameters of the flexible interconnected distribution network;

[0009] Establishing configuration constraints of the objective function according to node parameters of the flexible interconnected distribution network;

[0010] Based on the energy storage system constraints, the flexibility constraints and the configuration constraints, the objective function is solved to obtain an optimal configuration plan for energy storage in the flexible interconnected distribution network.

[0011] In a possible implementation, the energy storage parameters include the charge and discharge power, current capacity, rated power and rated capacity of the energy storage system; the energy storage system constraints include energy storage operation constraints and continuous working time constraints;

[0012] The energy storage system constraint conditions of the objective function are established according to the energy storage parameters of the energy storage system, including:

[0013] Establishing energy storage operation constraints for steady-state operation of the energy storage system according to the charge and discharge power, current capacity, rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network;

[0014] According to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset duration, and the continuous working time constraint condition of each energy storage system is obtained.

[0015] In a possible implementation, the flexibility constraint includes a ramping capability constraint and a net load fluctuation rate constraint;

[0016] The establishing of the flexibility constraint condition of the objective function according to the energy storage parameter, the inverter parameter of the distributed generation inverter in the flexible interconnected distribution network and the net load parameter of the flexible interconnected distribution network comprises:

[0017] Determining the flexibility supply capability of the flexible interconnected distribution network according to the energy storage parameters of the energy storage system at each node in the flexible interconnected distribution network and the inverter parameters of the distributed generation inverter at each node;

[0018] Determining the flexibility requirement of the flexible interconnected distribution network according to the net load parameters at each node in the flexible interconnected distribution network;

[0019] Establishing the ramping capability constraint condition based on the flexibility supply capability and the flexibility demand;

[0020] Calculating the net load fluctuation rate at each node according to the net load parameters at each node in the flexible interconnected distribution network;

[0021] The net load fluctuation rate constraint condition is established based on the net load fluctuation rate and a preset fluctuation rate threshold.

[0022] In a possible implementation, according to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset duration, and the continuous working time constraint condition of each energy storage system is obtained, including:

[0023] According to the expression: ERs,ESS =t ESS P Rs,ESS , respectively establish the continuous working time constraints of each energy storage system;

[0024] In the formula, E Rs,ESS represents the rated capacity of the energy storage system at node s, P Rs,ESS represents the rated power of the energy storage system at node s, t ESS Indicates the preset duration.

[0025] In a possible implementation, the flexibility supply capability includes flexibility upward climbing capability and flexibility downward climbing capability, and the flexibility demand includes flexibility upward climbing demand and flexibility downward climbing demand;

[0026] The step of establishing the ramp capability constraint condition based on the flexibility supply capability and the flexibility demand includes:

[0027] According to the expression: Establishing the gradeability constraint condition;

[0028] Where, FRU t It represents the flexibility upward climbing capability of the flexible interconnected distribution network in period t, URR t represents the upward flexibility demand of the flexible interconnected distribution network in period t, FRD t represents the downward flexibility climbing capability of the flexible interconnected distribution network in period t, DRR t represents the flexibility downward climbing demand of the flexible interconnected distribution network corresponding to the time period t, and T represents the total number of time periods in the scheduling cycle composed of the set of all time periods.

[0029] In a possible implementation, the establishing of the net load fluctuation rate constraint condition based on the net load fluctuation rate and a preset fluctuation rate threshold includes:

[0030] According to the expression: FRNL i ≤FRNL set ,i∈Ω b , establishing the net load fluctuation rate constraint condition;

[0031] Where FRNL i represents the net load fluctuation rate at node i, FRNL set represents the volatility threshold at node i, Ω b Represents a set of all nodes in the flexible interconnected distribution network.

[0032] In a possible implementation, the calculating the net load fluctuation rate at each node according to the net load parameter at each node in the flexible interconnected distribution network includes:

[0033] According to the expression: Calculate the net load fluctuation rate at each node respectively;

[0034] Where FRNL i represents the net load fluctuation rate at node i, σ i represents the load injection power variance at point i, S Ti represents the apparent capacity of the transformer at node i, P i,t represents the active power injected at node i during period t, represents the average injected power of node i during the scheduling period, Ω T represents a scheduling period consisting of a set of all time periods, and T represents the total number of all time periods in the scheduling period.

[0035] In a possible implementation, the objective function is expressed as:

[0036]

[0037] In the formula, C Total represents the sum of the annual investment cost of the energy storage system and the annual operation and maintenance cost of the distribution network, C EAI represents the annual investment cost of the energy storage system, C OM represents the annual operation and maintenance cost of the flexible interconnected distribution network, C NLC represents the daily network loss cost of the flexible interconnected distribution network, C PRC represents the daily electricity purchase cost from the upper main grid, C PC represents the daily penalty cost for abandoning light, C FRSC represents the daily dispatch cost of energy storage, r represents the discount rate, y represents the operating life of the energy storage system, c e represents the investment cost per unit capacity of the energy storage system, E Rs,ESS represents the rated capacity of the energy storage system at node s, c p represents the unit power investment cost of the energy storage system, P Rs,ESS represents the rated power of the energy storage system at node s, c loss Represents the unit power network loss cost, P i,t represents the active power injected at node i during period t, Δt represents the duration of each period, c g represents the unit price of electricity purchased from the upper power grid, P t g represents the power purchased from the upper power grid during period t, c ap It represents the penalty cost of abandoned light per unit power, represents the active power reduced by DG (Distributed Generations) at node k during period t, c ess Represents the operating cost of the unit power energy storage system, P s,t,ESS represents the charging and discharging power of the energy storage system at node s during period t, Ω ESS represents the set of all energy storage systems, Ω T represents the scheduling period consisting of the set of all time periods, Ω b represents the set of all nodes of the flexible interconnected distribution network, Ω DG Represents the set of all distributed generation inverters.

[0038] In a possible implementation, the configuration constraints include flexible switch constraints, distributed power inverter constraints, power flow constraints, and safety constraints.

[0039] In a second aspect, an embodiment of the present invention provides a flexible interconnected distribution network energy storage optimization configuration device, comprising:

[0040] The first establishment module is used to establish an objective function with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network within a preset time period;

[0041] The second establishment module is used to establish the energy storage system constraint conditions of the objective function according to the energy storage parameters of the energy storage system; establish the flexibility constraint conditions of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverter in the flexible interconnected distribution network and the net load parameters of the flexible interconnected distribution network; establish the configuration constraint conditions of the objective function according to the node parameters of the flexible interconnected distribution network;

[0042] A solution module is used to solve the objective function based on the energy storage system constraints, the flexibility constraints and the configuration constraints to obtain an optimal configuration plan for energy storage in a flexible interconnected distribution network.

[0043] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0044] The embodiment of the present invention establishes an objective function by taking the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network as the minimum as the goal, and establishes the energy storage system constraints and flexibility constraints of the objective function through the energy storage parameters of the energy storage system, the inverter parameters of the distributed power generation inverter in the flexible interconnected distribution network and the net load parameters of the flexible interconnected distribution network, so as to constrain the configuration of the energy storage system and the flexibility of the distribution network; then, the objective function is solved through the energy storage system constraints, the flexibility constraints and the established configuration constraints, and the energy storage optimization configuration scheme of the flexible interconnected distribution network is obtained, so as to optimize the configuration of the energy storage system and improve the regulation capability of the distribution network, thereby improving the flexibility of the distribution network and improving the supply and demand balance capability of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 This is an application scenario diagram of the method for optimizing energy storage configuration in a flexible interconnected distribution network provided by an embodiment of the present invention;

[0047] Figure 2 It is a flow chart of the implementation of the method for optimizing energy storage configuration of a flexible interconnected distribution network provided by an embodiment of the present invention;

[0048] Figure 3 is a schematic diagram of a ramp demand considering net load volatility and uncertainty provided by an embodiment of the present invention;

[0049] Figure 4 is a schematic diagram of a flexible switch provided by an embodiment of the present invention;

[0050] Figure 5 is a curve diagram of load factors and PV factors of 32 nodes in a distribution network provided by an embodiment of the present invention;

[0051] Figure 6 The embodiment of the present invention provides different FRNL set Schematic diagram of the total cost, investment cost and operation and maintenance cost curves under constraints and PV installed capacity;

[0052] Figure 7 The embodiment of the present invention provides different FRNL set Schematic diagram of the curves of various components of operation and maintenance costs under constraints and PV installed capacity;

[0053] Figure 8is a curve diagram of the flexible climbing capability and demand provided by an embodiment of the present invention;

[0054] Fig. 9 The embodiment of the present invention provides different FRNL set Schematic diagram of active power injection curve under constraints and PV installed capacity;

[0055] Fig.10 The embodiment of the present invention provides different FRNL set Schematic diagram of total installed capacity of ESS under constraints and PV installed capacity;

[0056] Fig.11 The embodiment of the present invention provides different FRNL set Schematic diagram of the detailed configuration of ESS for all nodes under constraints and PV installed capacity;

[0057] Fig.12 It is a structural schematic diagram of a flexible interconnected distribution network energy storage optimization configuration device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0059] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0060] Figure 1 This is a diagram of an application scenario of the method for optimizing energy storage configuration in a flexible interconnected distribution network provided in an embodiment of the present invention. Figure 1 A 33-node flexible interconnected distribution network is shown in the figure, in which a three-terminal flexible switch (flexible distribution switch, FDS) connecting node 18, node 22 and node 33 is configured, and 10 distributed photovoltaics (photovoltaic, PV) are configured at node 3, node 6, node 9, node 12, node 15, node 18, node 21, node 24, node 27 and node 30 respectively.

[0061] Here, the FDS, ESS, DG inverter, reactive power compensation device, network reconstruction, on-load tap-changing transformer, electric vehicle and interruptible load in the distribution system composed of the flexible interconnected distribution network have power regulation functions and can be regarded as flexibility resources. In this embodiment, the main focus is on the active power balance problem, so the three types of flexibility resources, FDS, ESS and DG inverter, are mainly considered.

[0062] Figure 2 The implementation flow chart of the method for optimizing energy storage configuration of a flexible interconnected distribution network provided by the embodiment of the present invention is described in detail as follows:

[0063] Step 201, establishing an objective function with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network.

[0064] In this embodiment, the investment cost of the energy storage system can be considered with the full life cycle cost of ESS, and the operation and maintenance cost of the flexible interconnected distribution network can be considered with the network loss cost, abandoned light cost, electricity purchase cost and dispatching cost. Thus, with the goal of minimizing the full life cycle cost of ESS, network loss cost, abandoned light penalty cost, electricity purchase cost and dispatching cost, an ESS optimization configuration model is established to obtain the objective function.

[0065] Here, the planning time can be one year to determine the annual investment cost, annual network loss cost and annual operation and maintenance cost. When determining the annual operation and maintenance cost, the network loss cost, abandoned light cost, electricity purchase cost and dispatching cost can be determined in days, that is, daily network loss cost, daily abandoned light penalty cost, daily electricity purchase cost and daily dispatching cost. Different time lengths can also be selected for calculation as needed.

[0066] Optionally, the objective function can be expressed as:

[0067]

[0068] In the formula, C Total represents the sum of the annual investment cost of the energy storage system and the annual operation and maintenance cost of the distribution network, C EAI represents the annual investment cost of the energy storage system, C OM represents the annual operation and maintenance cost of the flexible interconnected distribution network, C NLC represents the daily network loss cost of the flexible interconnected distribution network, C PRC represents the daily electricity purchase cost from the upper main grid, C PC represents the daily penalty cost for abandoning light, C FRSC represents the daily dispatch cost of energy storage, r represents the discount rate, y represents the operating life of the energy storage system, c e represents the investment cost per unit capacity of the energy storage system, E Rs,ESS represents the rated capacity of the energy storage system at node s, c pRepresents the investment cost per unit power of the energy storage system, P Rs,ESS represents the rated power of the energy storage system at node s, c loss Represents the unit power network loss cost, P i,t represents the active power injected at node i during period t, Δt represents the duration of each period, c g represents the unit price of electricity purchased from the upper power grid, P t g represents the power purchased from the upper power grid during period t, c ap It represents the penalty cost of abandoned light per unit power, represents the active power reduced by DG at node k during period t, c ess Represents the operating cost of the unit power energy storage system, P s,t,ESS represents the charging and discharging power of the energy storage system at node s during period t, Ω ESS represents the set of all energy storage systems, Ω T represents the scheduling period consisting of the set of all time periods, Ω T ={1,…,T},Ω b represents the set of all nodes in the flexible interconnected distribution network, Ω DG Represents the set of all distributed generation inverters.

[0069] Step 202: Establish energy storage system constraint conditions of the objective function according to energy storage parameters of the energy storage system.

[0070] In this embodiment, when establishing the energy storage system constraint conditions, not only the steady-state operation of the energy storage system is considered, but also the continuous working time of the energy storage system may be constrained to more accurately optimize the configuration of the energy storage system.

[0071] Optionally, the energy storage parameters include the charging and discharging power, current capacity, rated power and rated capacity of the energy storage system; the energy storage system constraints include energy storage operation constraints and continuous working time constraints.

[0072] This embodiment establishes the energy storage system constraint conditions of the objective function according to the energy storage parameters of the energy storage system. First, the energy storage operation constraint conditions of the steady-state operation of the energy storage system can be established according to the charging and discharging power, current capacity, rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network; then, according to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset duration, thereby obtaining the continuous working time constraint conditions of each energy storage system.

[0073] Here, for the energy storage system, each energy storage should meet the following constraints:;

[0074]

[0075] In the formula, represents the charging power of the energy storage system at node s during period t, represents the discharge power of the energy storage system at node s during period t, P Rs,ESS represents the rated power of the energy storage system at node s, is a binary variable, indicating the charging of the energy storage system at node s during period t. is a binary variable, indicating the discharge of the energy storage system at node s during period t, E s,t represents the amount of electricity stored in the energy storage system at node s during period t, E s,t-1 represents the amount of electricity stored in the energy storage system at node s during period t-1, represents the charging efficiency of the energy storage system at node s, represents the discharge efficiency of the energy storage system at node s, Δt represents the duration of each time period, and E Rs,ESS Indicates that SOC min Indicates the minimum state of charge of the energy storage system, SOC max Indicates the maximum state of charge of the energy storage system, E Rs,ESS represents the rated capacity of the energy storage system at node s, E s,0 represents the amount of electricity stored in the energy storage system at node s in period 0, E s,T represents the amount of electricity stored in the energy storage system at node s during period T, Represents the active power loss of the energy storage system at node s during period t.

[0076] In order to simplify the complexity of the model caused by binary variables, the ESS loss can be ignored, and the energy storage operation constraints can be:

[0077]

[0078] Optionally, this embodiment limits the maximum continuous working time of each energy storage system to a preset duration according to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, and obtains the continuous working time constraint condition of each energy storage system, which can be obtained according to the expression: E Rs,ESS =t ESS P Rs,ESS , and establish the continuous working time constraints of each energy storage system.

[0079] In the formula, E Rs,ESS represents the rated capacity of the energy storage system at node s, P Rs,ESS represents the rated power of the energy storage system at node s, t ESS Indicates the preset duration.

[0080] Here, the preset duration can be set to 2 hours, 3 hours, 4 hours, etc., and can be determined according to the specific needs of the energy storage system.

[0081] Step 203: Establish the flexibility constraint conditions of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverters in the flexible interconnected distribution network, and the net load parameters of the flexible interconnected distribution network.

[0082] The flexibility of the power system is defined as the ability to adapt to the random changes on both the supply and demand sides by coordinating various flexible resources within a certain time range. The flexibility can be modeled by calculating the flexibility requirements of each node during each scheduling period.

[0083] See Figure 3 the schematic diagram of the ramp-up requirements considering the volatility and uncertainty of the net load shown in

[0084] 1) At time t0, the net load is L0. The predicted value of the net load at time t1 and its upper and lower limits are L1, u1, and d1 respectively. Since d1 > L0, there is only a flexible ramp-up (FRU) requirement and no flexible ramp-down (FRD) requirement. Considering the prediction uncertainty, the FRU requirement FRU0 = u1 - L0.

[0085] 2) At time t1, the net load is L1. The predicted value of the load at time t2 and its upper and lower limits are L2, u2, and d2 respectively. Since d2 < L1 < u2, there are both FRU and FRD requirements. Considering the prediction uncertainty, FRU1 = u2 - L1 and FRD1 = L1 - d2.

[0086] 3) Similarly, at time t2, the net load is L2. The predicted value at time t3 and its upper and lower limits are L3, u3, and d3 respectively. Since d3 < L2 < u3, there are both FRU and FRD requirements. FRU2 = u3 - L2 and FRD2 = L2 - d3.

[0087] Based on this, the flexibility constraint conditions can be established using the FRU and FRD requirements.

[0088] Optionally, the flexibility constraint conditions include ramp-up capacity constraint conditions and net load volatility constraint conditions.

[0089] In this embodiment, the flexibility constraint conditions of the objective function established according to the energy storage parameters, the inverter parameters of the distributed generation inverters in the flexible interconnected distribution network, and the net load parameters of the flexible interconnected distribution network can be:

[0090] Step 2031, determining the flexibility supply capability of the flexible interconnected distribution network according to the energy storage parameters of the energy storage system at each node in the flexible interconnected distribution network and the inverter parameters of the distributed generation inverter at each node.

[0091] Here, the flexibility supply capacity includes flexibility upward climbing capacity and flexibility downward climbing capacity, which are mainly provided by the energy storage system and DG inverter, that is, the flexibility supply capacity can include energy storage flexibility supply capacity and inverter flexibility supply capacity.

[0092] Among them, the energy storage flexibility supply capacity may include the energy storage flexibility upward climbing capacity and the energy storage flexibility downward climbing capacity.

[0093] Specifically, it can be expressed as: Sure.

[0094] Accordingly, the inverter flexibility supply capability may include inverter flexibility up-climbing capability and inverter flexibility down-climbing capability.

[0095] Specifically, it can be expressed as: Sure.

[0096] Where, FRU s,t,ESS Indicates the upward climbing ability of energy storage flexibility, FRD s,t,ESS Indicates the downward climbing capability of energy storage flexibility, FRU k,t,DG Indicates the inverter's flexibility upward climbing capability, FRD k,t,DG Indicates the inverter's flexibility in ramping down. represents the active power reduced by DG at node k during period t, P k,t,DG It represents the active power output by DG at node k during period t.

[0097] Based on this, we can use the expression: Determine the flexibility supply capability of the flexible interconnected distribution network.

[0098] Where, FRU t represents the flexibility upward climbing capability of the flexible interconnected distribution network in period t, FRD t It represents the downward flexibility climbing capability of the flexible interconnected distribution network in period t.

[0099] Step 2032: Determine the flexibility requirement of the flexible interconnected distribution network according to the net load parameters at each node in the flexible interconnected distribution network.

[0100] Ignoring forecast uncertainty, the flexibility ramp-up demand and flexibility ramp-down demand of the entire system are defined as follows:

[0101]

[0102] Where URR i,t represents the upward flexibility demand at node i during period t, DRR i,t represents the downward flexibility demand at node i during period t, P i,t,NET represents the net load power at node i during period t, P i,t+1,NET represents the net load power at node i in period t+1. i,t,NET =P i,t,L -P i,t,DG , P i,t,L represents the active load at node i during period t, P i,t,DG represents the active power output of DG at node i during period t,

[0103] The flexibility requirement of the entire system can be:

[0104]

[0105] Where URR t represents the upward flexibility demand of the flexible interconnected distribution network during period t, DRR t represents the downward flexibility demand of the flexible interconnected distribution network during period t, Ω b \{root} represents the set of nodes except the root node.

[0106] Step 2033, establishing ramping capacity constraints based on flexibility supply capacity and flexibility demand.

[0107] In this embodiment, a ramp capacity constraint condition may be established through the relationship between supply and demand, so that the FRU / FRD capacity provided by the system is greater than the system FRU / FRD demand during the T-1 period.

[0108] Optionally, the flexibility supply capability includes flexibility upward climbing capability and flexibility downward climbing capability, and the flexibility demand includes flexibility upward climbing demand and flexibility downward climbing demand.

[0109] In this embodiment, based on the flexibility supply capability and the flexibility demand, a ramp capability constraint condition is established, which may be based on the expression: Establish gradeability constraints.

[0110] Where, FRU t It represents the flexibility upward climbing capability of the flexible interconnected distribution network in period t, URR t represents the upward flexibility demand of the flexible interconnected distribution network in period t, FRD t represents the downward flexibility climbing capability of the flexible interconnected distribution network in period t, DRR tIt represents the downward flexibility demand of the flexible interconnected distribution network corresponding to the period t, and T represents the total number of periods in the scheduling cycle composed of the set of all periods.

[0111] Step 2034, calculating the net load fluctuation rate at each node according to the net load parameters at each node in the flexible interconnected distribution network.

[0112] In this embodiment, in addition to the upward and downward flexibility supply and demand balance indicators, the net load fluctuation rate (FRNL) is introduced as another flexibility evaluation indicator.

[0113] Optionally, according to the net load parameters at each node in the flexible interconnected distribution network, the net load fluctuation rate at each node is calculated respectively, which can be expressed as follows: Calculate the net load fluctuation rate at each node respectively; where FRNL i represents the net load fluctuation rate at node i, σ i represents the load injection power variance at point i, S Ti represents the apparent capacity of the transformer at node i, P i,t represents the active power injected at node i during period t, represents the average injected power of node i during the scheduling period, Ω T represents the scheduling period consisting of the set of all time periods, and T represents the total number of all time periods in the scheduling period.

[0114] Step 2035: Establish a net load fluctuation rate constraint condition based on the net load fluctuation rate and a preset fluctuation rate threshold.

[0115] Optionally, based on the net load volatility and a preset volatility threshold, a net load volatility constraint condition is established, which can be based on the expression: FRNL i ≤FRNL set ,i∈Ω b , establish the net load fluctuation rate constraint condition; where FRNL i represents the net load fluctuation rate at node i, FRNL set represents the volatility threshold at node i, Ω b Represents the set of all nodes in the flexible interconnected distribution network.

[0116] Here, the constraint is used to ensure that the FRNL of all nodes is less than the preset threshold FRNL set .

[0117] Step 204: establishing configuration constraints of the objective function according to the node parameters of the flexible interconnected distribution network.

[0118] In this embodiment, in addition to the above constraints, configuration constraints may also be established to constrain the flexible interconnected distribution network and the DG inverter.

[0119] Step 205, based on the energy storage system constraints, flexibility constraints and configuration constraints, solve the objective function to obtain the flexible interconnected distribution network energy storage optimization configuration plan.

[0120] The embodiment of the present invention establishes an objective function by taking the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network as the minimum as the goal, and establishes the energy storage system constraints and flexibility constraints of the objective function through the energy storage parameters of the energy storage system, the inverter parameters of the distributed power generation inverter in the flexible interconnected distribution network and the net load parameters of the flexible interconnected distribution network, so as to constrain the configuration of the energy storage system and the flexibility of the distribution network; then, the objective function is solved through the energy storage system constraints, the flexibility constraints and the established configuration constraints, and the energy storage optimization configuration scheme of the flexible interconnected distribution network is obtained, so as to optimize the configuration of the energy storage system and improve the regulation capability of the distribution network, thereby improving the flexibility of the distribution network and improving the supply and demand balance capability of the distribution network.

[0121] In some embodiments, the configuration constraints include flexible switching constraints, distributed power inverter constraints, power flow constraints, and safety constraints.

[0122] Here, see Figure 4 The schematic diagram of the flexible switch shown in Figure 1 shows a typical multi-terminal back-to-back FDS consisting of multiple voltage source converters (VSCs). In normal operation mode, the control variables of the FDS are the active power and reactive power transmitted by each VSC. Assuming that the power injection direction of the grid is positive and ignoring power losses, each FDS should satisfy the following constraints, namely the flexible switch constraints:

[0123]

[0124] Where P u,t,FDS represents the active power injected by FDS at node u during period t, Q u,t,FDS represents the reactive power injected by FDS at node u during period t, S max,FDS Indicates the maximum apparent power of FDS, Ω b(v) Represents the node set associated with the vth FDS.

[0125] In most cases, the DG inverter operates in maximum power point tracking mode and can cut active power when overvoltage occurs. The following distributed power inverter constraints exist:

[0126]

[0127] In the formula, represents the active power reduced by DG at node k during period t, P k,t,DG It represents the active power output by DG at node k during period t.

[0128] For power flow constraints, the DistFlow power flow model can be used, as follows:

[0129]

[0130] Where P i,t represents the active power injected at node i during period t, P i,t,DG represents the active power output of DG at node i during period t, represents the active power reduced by DG at node i during period t, P i,t,L represents the active load at node i during period t, P i,t,FDS represents the active power injected by FDS at node i during period t, P i,t,ESS represents the charging and discharging power of ESS at node i during period t, Q i,t represents the reactive power injected at node i during period t, Q i,t,L represents the reactive load at node i during period t, Q i,t,FDS represents the reactive power injected by FDS at node i during period t, P ij,t represents the active power of the branch wi formed from node w to node i during period t, I wi,t represents the current amplitude of the branch wi formed from node w to node i during period t, r ij represents the resistance of the branch wi formed from node w to node i, P ij,t represents the active power of the branch ij formed from node i to node j during period t, Q ij,t represents the reactive power of the branch wi formed by node w to node i during period t, x ij represents the reactance of the branch wi formed from node w to node i, Q ij,t represents the reactive power of the branch ij formed by node i to node j during period t, V j,t represents the voltage amplitude of node j at time period t, V i,t represents the voltage amplitude of node i during period t, r ij represents the resistance of the branch ij formed from node i to node j, x ij represents the reactance of the branch ij formed from node i to node j, I ij,t represents the current amplitude of the branch ij formed from node i to node j during period t, Ω l Represents the set of all branches in the flexible interconnected distribution network.

[0131] For safety constraints, the voltage amplitude of each node cannot exceed its upper and lower limits, and the current amplitude of each line cannot exceed the line current carrying capacity, as follows:

[0132]

[0133] Where V min Indicates the voltage lower limit, V max Indicates the voltage upper limit, I ij,max Represents the current carrying capacity of the branch ij formed from node i to node j.

[0134] In some embodiments, due to the non-convexity of the power flow constraint, the model is a non-convex problem. At the same time, setting a net load fluctuation rate constraint for each node will introduce a large number of second-order cone constraints, which are difficult to solve quickly. Therefore, the non-convex power flow constraint can be subjected to second-order cone relaxation, and the net load fluctuation rate constraint can be converted into a linear constraint, so that the original non-convex model is converted into a second-order cone programming (SOCP) model, which can be efficiently solved by a mature solver.

[0135] Among them, the auxiliary variable u can be introduced i,t replace w wi,t replace w ij,t replace By using second-order cone relaxation, the power flow constraint can be reformulated as:

[0136]

[0137] Correspondingly, the security constraints can also be converted to:

[0138]

[0139] In addition, the variance form in net load volatility and its corresponding flexibility constraint are reformulated as:

[0140]

[0141] In the formula, σ i >0 is an auxiliary variable, indicating P i,t and The absolute deviation.

[0142] In some embodiments, using Figure 1 The proposed method is verified in the 33-node flexible interconnected distribution network shown in the figure. The objective function is established with the goal of minimizing the annual investment cost of ESS and the annual operation and maintenance cost of the distribution network. The parameters required for configuring the energy storage system can be found in Table 1 below:

[0143] Table 1 Parameters required to configure the energy storage system

[0144] parameter Numeric parameter Numeric <![CDATA[c e ]]> 1270￥ / kWh <![CDATA[c g ]]> 0.6￥ / kWh <![CDATA[c p ]]> 1650￥ / kWh <![CDATA[c ap ]]> 0.6￥ / kWh y 10years <![CDATA[c ess ]]> 0.08￥ / kWh r 0.1 <![CDATA[S T1 ]]> 6.3MVA <![CDATA[c loss ]]> 0.6￥ / kWh <![CDATA[S T2～33 ]]> 800kVA

[0145] The active and reactive load data of multiple actual substations are used, and the data collection frequency is 15 minutes. The typical day with the maximum load is selected as the worst scenario. The 96-point load curves of 32 substations are extracted, normalized to the interval of 0-1, and randomly assigned to each node of the 33-node distribution network; similarly, the actual 96-point photovoltaic power generation data of a typical day is normalized to the interval of 0-1 and assigned to 10 PVs. The load factor curves and PV factor curves of the 32 load nodes are shown in Figure 2. Figure 5 shown.

[0146] In different FRNL set The proposed method is tested under constraints and PV installed capacity. The installed capacities of 10 PVs are set to 100kW, 200kW, 300kW, 400kW and 500kW, respectively, and the total PV capacity is 1 to 5MW. In addition, the following two scenarios are designed for comparative analysis:

[0147] 1) Scenario 1: ESS configuration without considering the continuous working time constraint and flexibility constraint;

[0148] 2) Scenario 2: ESS configuration considering flexibility constraints, that is, the energy storage system is configured using the flexible interconnected distribution network energy storage optimization configuration method provided by the present invention (hereinafter referred to as "FC").

[0149] Different FRNL set Constraints and PV installed capacity under C EAI , C OM and C Total Curve like Figure 6 As shown, Figure 6 A shows different FRNL set Constraints and PV installed capacity under C EAI Curve B shows different FRNL set Constraints and PV installed capacity under C OM Curve C shows different FRNL set Constraints and PV installed capacity under C Total Curve. Figure 6 It can be seen that with FRNL set As the constraints tighten, both the annual investment cost and the annual total cost will increase, and when FRNL set When it drops to a certain threshold, the total cost suddenly increases. For example, if the installed capacity of 10 PV nodes is 300kW, when FRNL setWhen it is reduced to 50%, the total cost suddenly increases, and there are obvious inflection points. These inflection points provide effective references for PV planning: 1) When the installed capacity of PV is low (such as 100kW), the net load fluctuation level is also very low, so no additional ESS investment is required; 2) When the installed capacity of PV increases (such as 500kW), huge ESS investment is required to suppress the net load fluctuation to an acceptable level. Therefore, for this distribution network, when installing PV above 5MW, the ESS investment cost to avoid transformer overload will be very high, and the technical and economic efficiency will be poor. In addition, due to Figure 6 It can be seen that when flexibility constraints are considered, the investment cost and operation and maintenance cost only increase slightly.

[0150] Different FRNL set Constraints and PV installed capacity under C NLC , C PRC , C PC and C FRSC Curve like Figure 7 As shown, Figure 7 A shows different FRNL set Constraints and PV installed capacity under C NLC Curve B shows different FRNL set Constraints and PV installed capacity under C PRC Curve C shows different FRNL set Constraints and PV installed capacity under C PC Curve D shows different FRNL set Constraints and PV installed capacity under C FRSC Curve. Figure 7 It can be seen that with FRNL set As the constraints are tightened, the annual network loss cost increases first, and then decreases after the flexibility is introduced. For example, when the PV installed capacity is 400kW, C NLC The peak occurs at FRNL set =70%. This is because in FRNL set When starting to decrease, no additional ESS is required (see Figure 6 However, more PV power generation is cut, which results in more power being transmitted from the upper grid, thus increasing network losses. At this stage, it is more economical to cut PV power generation than to install ESS. NLC After the peak, installing ESS is more economical than cutting PV power generation, resulting in more PV power generation being absorbed and less power being transmitted from the upper grid, thereby reducing network losses. Figure 7 It can also be observed from C that the PV reduction cost first increases and then decreases.

[0151] On the other hand, when adding FRU / FRD constraints, this trend no longer exists and increases with FRNL. set As the constraints are tightened, the network loss cost and the abandoned light cost are reduced. This is because under the FRU / FRD constraints, a certain capacity of ESS is always required, so that the local consumption of PV power generation can always be achieved. set When the constraints are further tightened, the ESS configuration capacity increases, and the local consumption of PV power generation also increases monotonically, resulting in a decrease in network loss costs and abandoned solar power costs. set As the constraints are tightened, the dispatch cost of ESS increases rapidly, which indicates that the dispatch frequency of ESS has been greatly increased in order to reduce the net load fluctuation.

[0152] Photovoltaic installed capacity P PV =200kW, FRNL set = 60% FRU / FRD supply capacity and demand Figure 8 As shown. Figure 8 It can be seen that when the FRU / FRD constraints are not considered, the flexible FRU / FRD demand cannot be met in certain time periods; when the FRU / FRD constraints are added, the FRU / FRD demand can always be met throughout the day.

[0153] Different FRNL set The node active power injection curve under constraints and PV installed capacity is as follows: Fig. 9 As shown, Fig. 9 Only the results without considering FRU / FRD constraints are shown in Figure 2. Fig. 9 A in Figure 1 shows the active power injection curve of the root node, and B shows the active power injection curve of the 15-node PV. It can be seen that as FRNL set As the constraints are tightened, the net load fluctuation becomes more and more gentle, which shows that the configuration of ESS can significantly reduce the net load fluctuation and thus delay the expansion of transformer capacity.

[0154] Different FRNL set The total configuration capacity of ESS under the constraints and PV installed capacity is as follows: Fig.10 The detailed configuration of ESS for all nodes is shown in Fig.11 As shown. Fig.11 In Figure 1, A shows the different FRNL values ​​when the installed PV capacity of each photovoltaic node is 100kW. set Detailed configuration of ESS constraining all nodes; B shows different FRNL when the PV installed capacity of each photovoltaic node is 200kW set Detailed configuration of ESS constraining all nodes; C shows the different FRNL when the PV installed capacity of each photovoltaic node is 300kW setDetailed configuration of ESS constraining all nodes; D shows different FRNL when the PV installed capacity of each photovoltaic node is 400kW set Detailed configuration of ESS constraining all nodes; E shows the different FRNL when the PV installed capacity of each photovoltaic node is 500kW set Constrain the detailed configuration of ESS for all nodes.

[0155] Depend on Fig.11 It can be seen that most ESSs are installed on PV nodes, among which PV node 18 is not equipped with energy storage because the node is interconnected with other feeders through a three-terminal FDS. set As the constraints are tightened, the ESS configuration capacity increases rapidly. In addition, the ESS is not installed at node 1 of the distribution substation, which shows that the hierarchical configuration method of combining the substation centralized ESS with other distributed local ESS is not economically advantageous.

[0156] In this embodiment of the present invention, under the premise of satisfying safety constraints, an ESS optimization configuration model is established with the goal of minimizing the ESS life cycle cost, network loss cost, abandoned light cost, power purchase cost and dispatch cost, and upward / downward flexibility adjustment power constraints and node net load fluctuation rate constraints are introduced to improve the distribution network's ability to cope with supply and demand balance, and then the non-convex model is transformed into a second-order cone programming problem for efficient solution. The effectiveness of the proposed method is verified by testing the improved 33-node flexible distribution network example and sensitivity analysis under different user flexibility preferences, and the following conclusions are obtained:

[0157] 1) The introduction of net load fluctuation rate constraints provides planners with an intuitive reference for evaluating and improving the PV carrying capacity of distribution networks;

[0158] 2) Only a slight increase in ESS investment cost is required to improve the system's flexibility and ability to adjust upwards / downwards;

[0159] 3) The hierarchical configuration of centralized ESS in substations and other distributed local ESS is not economically advantageous.

[0160] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0161] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0162] Fig.12The schematic diagram of the structure of the flexible interconnected distribution network energy storage optimization configuration device provided by the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0163] like Fig.12 As shown, the flexible interconnected distribution network energy storage optimization configuration device 120 includes:

[0164] The first establishing module 1201 is used to establish an objective function with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network within a preset time period;

[0165] The second establishing module 1202 is used to establish the energy storage system constraint conditions of the objective function according to the energy storage parameters of the energy storage system; establish the flexibility constraint conditions of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverter in the flexible interconnected distribution network and the net load parameters of the flexible interconnected distribution network; establish the configuration constraint conditions of the objective function according to the node parameters of the flexible interconnected distribution network;

[0166] The solution module 1203 is used to solve the objective function based on the energy storage system constraints, flexibility constraints and configuration constraints to obtain the energy storage optimization configuration plan for the flexible interconnected distribution network.

[0167] In a possible implementation, the energy storage parameters include the charging and discharging power, current capacity, rated power and rated capacity of the energy storage system; the energy storage system constraints include energy storage operation constraints and continuous working time constraints;

[0168] The second establishing module 1202 is specifically used for:

[0169] According to the charging and discharging power, current capacity, rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the energy storage operation constraint conditions for the steady-state operation of the energy storage system are established;

[0170] According to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset duration, and the continuous working time constraint conditions of each energy storage system are obtained.

[0171] In a possible implementation, the flexibility constraint includes a ramping capability constraint and a net load fluctuation rate constraint;

[0172] The second establishing module 1202 is specifically used for:

[0173] Determine the flexibility supply capability of the flexible interconnected distribution network based on the energy storage parameters of the energy storage system at each node in the flexible interconnected distribution network and the inverter parameters of the distributed generation inverter at each node;

[0174] Determine the flexibility requirement of the flexible interconnected distribution network according to the net load parameters at each node in the flexible interconnected distribution network;

[0175] Establish ramping capacity constraints based on flexibility supply capacity and flexibility demand;

[0176] According to the net load parameters at each node in the flexible interconnected distribution network, the net load fluctuation rate at each node is calculated respectively;

[0177] Based on the net load fluctuation rate and the preset fluctuation rate threshold, a net load fluctuation rate constraint condition is established.

[0178] In a possible implementation, the second establishing module 1202 is specifically configured to:

[0179] According to the expression: E Rs,ESS =t ESS P Rs,ESS , respectively establish the continuous working time constraints of each energy storage system;

[0180] In the formula, E Rs,ESS represents the rated capacity of the energy storage system at node s, P Rs,ESS represents the rated power of the energy storage system at node s, t ESS Indicates the preset duration.

[0181] In a possible implementation, the flexibility supply capability includes flexibility upward climbing capability and flexibility downward climbing capability, and the flexibility demand includes flexibility upward climbing demand and flexibility downward climbing demand; the second establishing module 1202 is specifically used to:

[0182] According to the expression: Establishing gradeability constraints;

[0183] Where, FRU t It represents the flexibility upward climbing capability of the flexible interconnected distribution network in period t, URR t represents the upward flexibility demand of the flexible interconnected distribution network in period t, FRD t represents the downward flexibility climbing capability of the flexible interconnected distribution network in period t, DRR t It represents the downward flexibility demand of the flexible interconnected distribution network corresponding to the period t, and T represents the total number of periods in the scheduling cycle composed of the set of all periods.

[0184] In a possible implementation, the second establishing module 1202 is specifically configured to:

[0185] According to the expression: FRNL i ≤FRNL set ,i∈Ωb , establish net load fluctuation rate constraint conditions;

[0186] Where FRNL i represents the net load fluctuation rate at node i, FRNL set represents the volatility threshold at node i, Ω b Represents the set of all nodes in the flexible interconnected distribution network.

[0187] In a possible implementation, the second establishing module 1202 is specifically configured to:

[0188] According to the expression: Calculate the net load fluctuation rate at each node respectively;

[0189] Where FRNL i represents the net load fluctuation rate at node i, σ i represents the load injection power variance at point i, S Ti represents the apparent capacity of the transformer at node i, P i,t represents the active power injected at node i during period t, represents the average injected power of node i during the scheduling period, Ω T represents the scheduling period consisting of the set of all time periods, and T represents the total number of all time periods in the scheduling period.

[0190] In one possible implementation, the objective function is expressed as:

[0191]

[0192] In the formula, C Total represents the sum of the annual investment cost of the energy storage system and the annual operation and maintenance cost of the distribution network, C EAI represents the annual investment cost of the energy storage system, C OM represents the annual operation and maintenance cost of the flexible interconnected distribution network, C NLC represents the daily network loss cost of the flexible interconnected distribution network, C PRC represents the daily electricity purchase cost from the upper main grid, C PC represents the daily penalty cost for abandoning light, C FRSC represents the daily energy storage dispatch cost, r represents the discount rate, y represents the operating life of the energy storage system, c e represents the investment cost per unit capacity of the energy storage system, E Rs,ESS represents the rated capacity of the energy storage system at node s, c p Represents the investment cost per unit power of the energy storage system, P Rs,ESS represents the rated power of the energy storage system at node s, c loss Represents the unit power network loss cost, P i,trepresents the active power injected at node i during period t, Δt represents the duration of each period, c g represents the unit price of electricity purchased from the upper power grid, P t g represents the power purchased from the upper power grid during period t, c ap It represents the penalty cost of abandoned light per unit power, represents the active power reduced by DG at node k during period t, c ess Represents the operating cost of the unit power energy storage system, P s,t,ESS represents the charging and discharging power of the energy storage system at node s during period t, Ω ESS represents the set of all energy storage systems, Ω T represents the scheduling period consisting of the set of all time periods, Ω b represents the set of all nodes in the flexible interconnected distribution network, Ω DG Represents the set of all distributed generation inverters.

[0193] In a possible implementation, the configuration constraints include flexible switch constraints, distributed power inverter constraints, power flow constraints, and safety constraints.

[0194] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0195] Those of ordinary skill in the art will appreciate that the templates, units, 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 the present invention.

[0196] If the module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable media may include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0197] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A method for optimizing energy storage configuration in a flexible interconnected distribution network, characterized in that: include: The objective function is established with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network. Establishing energy storage system constraints of the objective function according to energy storage parameters of the energy storage system; Establishing flexibility constraints of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverter in the flexible interconnected distribution network, and the net load parameters of the flexible interconnected distribution network; Establishing configuration constraints of the objective function according to node parameters of the flexible interconnected distribution network; Based on the energy storage system constraints, the flexibility constraints and the configuration constraints, the objective function is solved to obtain an optimal configuration plan for energy storage in the flexible interconnected distribution network.

2. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 1, characterized in that: The energy storage parameters include the charging and discharging power, current capacity, rated power and rated capacity of the energy storage system; the energy storage system constraints include energy storage operation constraints and continuous working time constraints; The energy storage system constraint conditions of the objective function are established according to the energy storage parameters of the energy storage system, including: Establishing energy storage operation constraints for steady-state operation of the energy storage system according to the charge and discharge power, current capacity, rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network; According to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset duration, and the continuous working time constraint condition of each energy storage system is obtained.

3. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 1, characterized in that: Flexibility constraints include ramping capability constraints and net load fluctuation rate constraints; The establishing of the flexibility constraint condition of the objective function according to the energy storage parameter, the inverter parameter of the distributed generation inverter in the flexible interconnected distribution network and the net load parameter of the flexible interconnected distribution network comprises: Determining the flexibility supply capability of the flexible interconnected distribution network according to the energy storage parameters of the energy storage system at each node in the flexible interconnected distribution network and the inverter parameters of the distributed generation inverter at each node; Determining the flexibility requirement of the flexible interconnected distribution network according to the net load parameters at each node in the flexible interconnected distribution network; Establishing the ramping capability constraint condition based on the flexibility supply capability and the flexibility demand; Calculating the net load fluctuation rate at each node according to the net load parameters at each node in the flexible interconnected distribution network; The net load fluctuation rate constraint condition is established based on the net load fluctuation rate and a preset fluctuation rate threshold.

4. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 2, characterized in that: According to the rated power and rated capacity of the energy storage system at each node in the flexible interconnected distribution network, the maximum continuous working time of each energy storage system is limited to a preset time length, and the continuous working time constraint conditions of each energy storage system are obtained, including: According to the expression: E Rs,ESS =t ESS P Rs,ESS , respectively establish the continuous working time constraints of each energy storage system; In the formula, E Rs,ESS represents the rated capacity of the energy storage system at node s, P Rs,ESS represents the rated power of the energy storage system at node s, t ESS Indicates the preset duration.

5. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 3, characterized in that: The flexibility supply capability includes the flexibility upward climbing capability and the flexibility downward climbing capability, and the flexibility demand includes the flexibility upward climbing demand and the flexibility downward climbing demand; The step of establishing the ramp capability constraint condition based on the flexibility supply capability and the flexibility demand includes: According to the expression: Establishing the gradeability constraint condition; In the formula, FRU t It represents the flexibility upward climbing capability of the flexible interconnected distribution network in period t, URR t represents the upward flexibility demand of the flexible interconnected distribution network in period t, FRD t represents the downward flexibility climbing capability of the flexible interconnected distribution network in period t, DRR t represents the flexibility downward climbing demand of the flexible interconnected distribution network corresponding to the time period t, and T represents the total number of time periods in the scheduling cycle composed of the set of all time periods.

6. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 3, characterized in that: The establishing of the net load fluctuation rate constraint condition based on the net load fluctuation rate and a preset fluctuation rate threshold comprises: According to the expression: FRNL i ≤FRNL set ,i∈Ω b , establishing the net load fluctuation rate constraint condition; In the formula, FRNL i represents the net load fluctuation rate at node i, FRNL set represents the volatility threshold at node i, Ω b Represents a set of all nodes in the flexible interconnected distribution network.

7. The method for optimizing energy storage configuration of a flexible interconnected distribution network according to claim 3, characterized in that: The calculating the net load fluctuation rate at each node according to the net load parameter at each node in the flexible interconnected distribution network comprises: According to the expression: Calculate the net load fluctuation rate at each node respectively; Where FRNL i represents the net load fluctuation rate at node i, σ i represents the load injection power variance at point i, S Ti represents the apparent capacity of the transformer at node i, P i,t represents the active power injected at node i during period t, represents the average injected power of node i during the scheduling period, Ω T represents a scheduling period consisting of a set of all time periods, and T represents the total number of all time periods in the scheduling period.

8. The method for optimizing energy storage configuration in a flexible interconnected distribution network according to any one of claims 1 to 7, characterized in that: The expression of the objective function is: In the formula, C Total represents the sum of the annual investment cost of the energy storage system and the annual operation and maintenance cost of the distribution network, C EAI represents the annual investment cost of the energy storage system, C OM represents the annual operation and maintenance cost of the flexible interconnected distribution network, C NLC represents the daily network loss cost of the flexible interconnected distribution network, C PRC represents the daily electricity purchase cost from the upper main grid, C PC represents the daily penalty cost for abandoning light, C FRSC represents the daily dispatch cost of energy storage, r represents the discount rate, y represents the operating life of the energy storage system, c e represents the investment cost per unit capacity of the energy storage system, E Rs,ESS represents the rated capacity of the energy storage system at node s, c p represents the unit power investment cost of the energy storage system, P Rs,ESS represents the rated power of the energy storage system at node s, c loss Represents the unit power network loss cost, P i,t represents the active power injected at node i during period t, Δt represents the duration of each period, c g represents the unit price of electricity purchased from the upper power grid, P t g represents the power purchased from the upper power grid during period t, c ap It represents the penalty cost of abandoned light per unit power, represents the active power reduced by DG at node k during period t, c ess Represents the operating cost of the unit power energy storage system, P s,t,ESS represents the charging and discharging power of the energy storage system at node s during period t, Ω ESS represents the set of all energy storage systems, Ω T represents the scheduling period consisting of the set of all time periods, Ω b represents the set of all nodes of the flexible interconnected distribution network, Ω DG Represents the set of all distributed generation inverters.

9. The method for optimizing energy storage configuration in a flexible interconnected distribution network according to any one of claims 1 to 7, characterized in that: The configuration constraints include flexible switch constraints, distributed power inverter constraints, power flow constraints and safety constraints.

10. A flexible interconnected distribution network energy storage optimization configuration device, characterized in that: include: The first establishment module is used to establish an objective function with the goal of minimizing the sum of the investment cost of the energy storage system and the operation and maintenance cost of the flexible interconnected distribution network within a preset time period; The second establishment module is used to establish the energy storage system constraint conditions of the objective function according to the energy storage parameters of the energy storage system; establish the flexibility constraint conditions of the objective function according to the energy storage parameters, the inverter parameters of the distributed generation inverter in the flexible interconnected distribution network and the net load parameters of the flexible interconnected distribution network; establish the configuration constraint conditions of the objective function according to the node parameters of the flexible interconnected distribution network; A solution module is used to solve the objective function based on the energy storage system constraints, the flexibility constraints and the configuration constraints to obtain an optimal configuration plan for energy storage in a flexible interconnected distribution network.

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