Power distribution network dispatching method and system, computer program product

Abstract

The application discloses a power distribution network scheduling method and system, and a computer program product, and belongs to the technical field of smart grids, and comprises the following steps: dividing a power distribution network into multiple power distribution network levels according to voltage grades, collecting data of each power distribution network level, setting a minimum total cost of virtual power plant output as a target function, and constructing an optimization model; starting from a lower power distribution network level, sequentially and independently calculating power flow of each power distribution network level, equivalently taking first-end injected power of the lower power distribution network level as corresponding node load of an upper level, outputting power flow operation conditions of each power distribution network level, establishing a power flow checking constraint model, judging whether the safety operation checking constraint is met, if yes, solving the optimization model by using an optimization algorithm to obtain the minimum total cost and corresponding output values of an output unit group, and if not, reassigning data to perform a new round of optimization. The application considers inverse-level dynamic coupling modeling of grid connection of new power generation units, and provides an integrated solution for dynamic safety and economic scheduling of the power distribution network.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of smart grid, and particularly to a power distribution network dispatching method and system, and a computer program product. BACKGROUND

[0002] In recent years, with the rapid development of renewable energy technology, the energy structure is transforming towards low carbonization and intelligence, which makes the scale and type of distributed resources grow rapidly. The access of large-scale distributed resources not only promotes energy transformation, but also brings technical challenges such as voltage fluctuation, reverse power flow, and complex protection and control to the power distribution network, which puts higher requirements on the flexibility and stability of the traditional centralized power system.

[0003] Virtual power plant (VPP) is a way of coordinated management of power system based on intelligent control technology, which aggregates new energy and other new power generation units, energy storage systems, flexible loads and fast response resources to build a virtual power aggregation body with multi-level coordinated dispatching capability. However, there are still some key technical defects in the application of existing virtual power plant technology in the power distribution network level, which restricts the actual effectiveness of virtual power plant from system modeling, operation optimization to market mechanism.

[0004] At the level of technical modeling, the existing scheme generally adopts a hierarchical independent modeling method, which only performs power flow calculation for a single voltage level, and does not fully consider the power injection effect of the upper layer power grid on the lower layer power grid. The lack of cross-level coupling effect leads to obvious limitations in safety inspection results. In terms of cross-level coordinated control, the existing technology lacks the integration of global constraints for multi-voltage level power grid, resulting in a mismatch between dispatching instructions and actual carrying capacity of the power grid. SUMMARY

[0005] The present application aims to provide a power distribution network dispatching method and system, and a computer program product considering multi-level power distribution network power flow safety inspection and optimization.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is:

[0007] A power distribution network dispatching method, comprising,

[0008] Step S1: dividing the power distribution network into multiple power distribution network levels according to voltage levels, each power distribution network level comprising multiple network frames;

[0009] Step S2: collecting data of each power distribution network level, setting the minimum total cost of virtual power plant output as the objective function, and constructing a virtual power plant output cost optimization model;

[0010] Step S3: input the collected data of each power distribution network level, independently calculate the power flow of each power distribution network level in turn from the lowest voltage level of the power distribution network level, and equivalently output the power injection of the first end of the low voltage level of the power distribution network level as the node load of the high voltage level of the power distribution network level, and output the power flow operation of each power distribution network level;

[0011] Step S4: establish a power flow checking constraint model of each power distribution network level, perform power flow checking of each power distribution network level according to the power flow operation of each power distribution network level, and judge whether the power flow of each power distribution network level meets the safety operation checking constraint, if yes, go to step S5, if not, go to step S6;

[0012] Step S5: solve the virtual power plant output cost optimization model by using an optimization algorithm to obtain the lowest total cost of the virtual power plant output of the power distribution network and the corresponding virtual power plant output unit group output value of each power distribution network level;

[0013] Step S6: reassign the collected data of each power distribution network level, and return to step S2.

[0014] Optionally, the collected data of each power distribution network level includes: the active load and reactive load of the node load of the grid frame of each power distribution network level, the active output and reactive output of the distributed power unit output of the grid frame of each power distribution network level, the active output and reactive output of the virtual power plant output unit group output of the grid frame of each power distribution network level, the virtual power plant output unit group offer, and the branch resistance and reactance of the grid frame of each power distribution network level.

[0015] Optionally, the objective function of the virtual power plant output cost optimization model is represented as follows:

[0016]

[0017] wherein, OBJ eco represents the lowest total cost of the virtual power plant output, represents the offer of the i-th virtual power plant output unit group of the n-th grid frame of the m-th power distribution network level. m represents the active output of the i-th virtual power plant output unit group of the n-th grid frame of the m-th power distribution network level. m

[0018] Optionally, the constraint conditions of the virtual power plant output cost optimization model include: power flow checking constraint of each power distribution network level and upper and lower limit constraint of virtual power plant output unit group processing; the upper and lower limit constraint of virtual power plant output unit group processing is represented as follows:

[0019]

[0020] wherein, represents the n-th grid frame of the m-th power distribution network level.​​m Lower limit of active power output of the j-th virtual power plant output unit group in the grid structure Represents the nth level of the m-th distribution network level m The upper limit of active power output of the j-th virtual power plant output unit group in the grid structure. Represents the nth level of the m-th distribution network level m Lower limit of reactive power output of the j-th virtual power plant output unit group in the grid structure Represents the nth level of the m-th distribution network level m The upper limit of reactive power output of the j-th virtual power plant output unit group in the grid structure.

[0021] Optionally, step S3 specifically includes:

[0022] Input the collected data from each level of the power distribution network;

[0023] Perform distribution network hierarchy division and initialization, setting the distribution network hierarchy to start from the distribution network hierarchy with the lowest voltage level; set the network structure of each distribution network hierarchy to start from the network structure with the smallest sorting mark;

[0024] Within the upper and lower limits of the virtual power plant output unit group processing, the variables of the virtual power plant output cost optimization model are randomly assigned values;

[0025] Independent power flow calculations are performed on each grid structure at the distribution network level in sequence;

[0026] The power injected at the beginning of the distribution network hierarchy at a low voltage level is equivalent to the load of the node in the distribution network hierarchy at a higher voltage level.

[0027] Determine if the number of distribution network levels is equal to the highest number of distribution network levels. If not, increment the voltage level of the distribution network level by 1, perform power flow calculations on each grid structure of the distribution network level one voltage level higher, and continue to determine if the number of distribution network levels is equal to the highest number of distribution network levels. If yes, output the power flow operation status of each branch of each grid structure in all distribution network levels, including: branch current of each distribution network level, node voltage of each distribution network level, and branch power of each distribution network level.

[0028] Optionally, independent power flow calculations can be performed on each network structure at a certain distribution network level, as shown below:

[0029]

[0030] in, Represents the nth level of the m-th distribution network level m The current flowing on the branch connecting two nodes ij in a network structure. Represents the nth level of the m-th distribution network level m The corresponding active power flowing on the branch connecting two nodes of a network structure. represents the corresponding active power flowing on the branch connected between nodes i and j of the nth grid of the mth hierarchical level of the distribution network, m represents the corresponding reactive power flowing on the branch connected between nodes i and j of the nth grid of the mth hierarchical level of the distribution network, m represents the voltage of node i of the nth grid of the mth hierarchical level of the distribution network, m represents the voltage of node j of the nth grid of the mth hierarchical level of the distribution network, m represents the branch resistance on the branch connected between nodes i and j of the nth grid of the mth hierarchical level of the distribution network, m represents the branch reactance on the branch connected between nodes i and j of the nth grid of the mth hierarchical level of the distribution network, m represents the active power output of the distributed generator unit at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the reactive power output of the distributed generator unit at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the active power output of the virtual power plant output unit group at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the reactive power output of the virtual power plant output unit group at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the active load of the node load at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the reactive load of the node load at node j of the nth grid of the mth hierarchical level of the distribution network, m represents the equivalent active load of the node load at node i of the nth grid of the mth hierarchical level of the distribution network, m represents the equivalent reactive load of the node load at node i of the nth grid of the mth hierarchical level of the distribution network, m represents the corresponding active power flowing on the branch connected between nodes j and k of the nth grid of the mth hierarchical level of the distribution network, m

[0031] Optionally, the power injected at the head of the grid of the distribution network at the low voltage level is equivalent to the corresponding node load of the grid of the distribution network at the high voltage level, which is represented as follows:

[0032] ​​​​​​​​​​​​​​​

[0033] wherein, Pm,n,i represents the active power injected by the first end of the nth m grid frame of the mth layer of the power distribution network, Qm,n,i represents the reactive power injected by the first end of the nth m grid frame of the mth layer of the power distribution network, Rm+1,n,i represents the equivalent active load of the ith node of the nth m+1 grid frame of the (m+1)th layer of the power distribution network, Xm+1,n,i represents the equivalent reactive load of the ith node of the nth m+1 grid frame of the (m+1)th layer of the power distribution network.

[0034] Optionally, the safe operation verification constraints include: voltage safety constraints, branch power and current safe operation constraints;

[0035] The voltage safety constraints are represented as follows:

[0036]

[0037] wherein, Vmin,m,n,i represents the lower limit of the voltage of node i of the nth m grid frame of the mth layer of the power distribution network, Vmax,m,n,i represents the upper limit of the voltage of node i of the nth m grid frame of the mth layer of the power distribution network;

[0038] The branch power and current safe operation constraints are represented as follows:

[0039]

[0040] wherein, Imax,m,n,i represents the upper limit of the current flowing on the branch connecting the two nodes i and j of the nth m grid frame of the mth layer of the power distribution network, Smax,m,n,i represents the apparent power on the branch connecting the two nodes i and j of the nth m grid frame of the mth layer of the power distribution network; Km,n represents the branch power safety margin coefficient of the nth m grid frame of the mth layer of the power distribution network; Smax,m,n,i represents the upper limit of the apparent power on the branch connecting the two nodes i and j of the nth m grid frame of the mth layer of the power distribution network.

[0041] The power distribution network dispatching system is used for executing the power distribution network dispatching method, and comprises a virtual power plant output cost optimization module, wherein the virtual power plant output cost optimization module comprises power distribution network level flow calculation units and power distribution network level flow verification units; the power distribution network level flow calculation units are connected with the power distribution network level flow verification units.

[0042] The computer program product comprises a computer program, which is executed by a processor to implement the steps of the power distribution network dispatching method.

[0043] The power distribution network dispatching method and system, and the computer program product provided by the application consider inverse-level dynamic coupling modeling of grid connection of new energy and other new power generation units, accurately quantify the cascading effect of grid connection of large-scale new energy and other new power generation units on the power distribution network, ensure that all line powers are within the dynamic safety limit value constraint, realize accurate analysis of cross-level power distribution networks, and solve the problems of power flow fluctuation of multi-voltage level power distribution networks caused by distributed new energy and other new power generation units and the influence on power flow operation stability and cross-level coupling. A multi-dimensional safety checking system comprehensively guarantees operation safety. Meanwhile, the safety operation checking constraint and the economic optimization objective function of the lowest total cost of virtual power plant output are uniformly modeled, the virtual power plant output unit group configuration is optimized, the new energy and other new power generation unit fluctuation is coordinated, the optimal operation cost is realized, and an integrated solution of dynamic safety and economic dispatching of new energy and other new power generation unit power distribution networks is provided, which provides high-reliability and high-economy dispatching support for new power systems.

[0044] To make the above features and advantages of the application more obvious and easy to understand, the following embodiments are specifically described below, and the accompanying drawings are described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The flowchart of the power distribution network dispatching method provided by the application is shown.

[0046] Figure 2 The structure diagram of the multi-voltage level power distribution network is shown.

[0047] Figure 3 The interconnected network structure diagram of the power distribution network level 1 is shown.

[0048] Figure 4 The module diagram of the power distribution network dispatching system provided by the application is shown. DETAILED DESCRIPTION

[0049] In order to make the technical scheme of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0050] In an embodiment of the present application, referring to Figure 1 , Figure 1 The flowchart of the power distribution network dispatching method provided by the present application, the power distribution network dispatching method provided by the present application, and the power distribution network dispatching from bottom to top in multiple voltage levels are as follows: steps S1-S5.

[0051] Step S1: The power distribution network is divided into multiple power distribution network levels according to voltage levels, and each power distribution network level includes multiple network frames.

[0052] Step S2: Collect data of each power distribution network level, set the lowest total cost of virtual power plant output as the objective function, and construct a virtual power plant output cost optimization model.

[0053] Step S3: Input the collected data of each power distribution network level, and independently calculate the power flow of each power distribution network level from the lowest voltage level of the power distribution network level, and equivalently inject the power of the first end of the low-voltage level power distribution network level as the node load of the high-voltage level power distribution network level, and output the power flow operation of each power distribution network level.

[0054] Step S4: Establish a power flow checking constraint model for each power distribution network level, and perform power flow checking for each power distribution network level according to the power flow operation of each power distribution network level, and determine whether the power flow of each power distribution network level meets the safety operation checking constraint. If yes, go to step S5, if no, go to step S6.

[0055] Step S5: The virtual power plant output cost optimization model is solved by using an optimization algorithm to obtain the lowest total cost of the virtual power plant output of the power distribution network and the corresponding virtual power plant output unit group output value of each power distribution network level.

[0056] Step S6: Reassign the collected data of each power distribution network level, and return to step S2.

[0057] In step S1, referring to the S1 step in Figure 1 , the power distribution network is divided into multiple power distribution network levels according to voltage levels, and each power distribution network level includes multiple network frames.

[0058] As an example, there are multiple voltage levels in the power distribution network, referring to Figure 2 , Figure 2A multi-voltage level power distribution network structure schematic diagram is shown. The power distribution network is divided into M power distribution network levels according to voltage levels. Specifically, the M power distribution network levels include power distribution network level 1 to power distribution network level M. Power distribution network level 1 represents the lowest voltage level, and power distribution network level M represents the highest voltage level. The lower power distribution network level refers to the power distribution network level with a smaller voltage level, and the upper power distribution network level refers to the power distribution network level with a larger voltage level.

[0059] Each power distribution network level includes N m independent or interconnected power grid structure units, i.e., a grid, and the number of grids included in each power distribution network level can be different. N m represents the number of grids in the mth power distribution network level. Please refer to Figure 3 , Figure 3 A schematic diagram of interconnected grid structure of power distribution network level 1 is shown. Specifically, taking power distribution network level 1 as an example, N1 grids include grid 11 to grid 1N1.

[0060] Specifically, each grid includes nodes, which represent power connection points within the grid, represents the number of nodes in the nth m grid of the mth power distribution network level, where m∈{1,2,…,M}, n m ∈{1,2,…,N max}, and N max is determined by the maximum number of grids in the power distribution network level. All nodes contained in each grid have corresponding types, such as load nodes, distributed power unit nodes, and virtual power plant output nodes. A node can contain multiple types. The node load in the load node includes active load and reactive load The distributed power unit output in the distributed power unit node includes active output and reactive output The virtual power plant output unit group output in the virtual power plant output node includes active output and reactive output where i represents the ith node, and j represents the jth node.

[0061] Specifically, each grid also contains multiple branches, which represent lines or transformers connecting nodes. The parameters of each branch include resistance and reactance

[0062] In step S2, please refer to the S2 step in Figure 1 Collect data for each power distribution network level, set the minimum virtual power plant output total cost as the objective function, and build a virtual power plant output cost optimization model.

[0063] As an example, the collected data of each power distribution grid level includes: active load of node load of each power distribution grid level network framework and reactive load active output of distributed power unit group of each power distribution grid level network framework and reactive output active output of virtual power plant output unit group of each power distribution grid level network framework and reactive output virtual power plant output unit group offer branch resistance of each power distribution grid level network framework and reactance

[0064] Among them, the active output and reactive output of the virtual power plant output unit group of each power distribution grid level network framework are the optimization variables of the virtual power plant output cost optimization model.

[0065] As an example, the virtual power plant output total cost is set as the objective function, and the virtual power plant output cost optimization model is constructed, which is expressed as follows:

[0066]

[0067] Among them, OBJ eco represents the lowest total cost of virtual power plant output, represents the offer of the i-th virtual power plant output unit group of the n m th network framework of the m-th power distribution grid level; represents the active output of the i-th virtual power plant output unit group of the n m th network framework of the m-th power grid.

[0068] Further, the upper and lower limit constraints of the virtual power plant output unit group are the first constraint conditions of the virtual power plant output cost optimization model, which are expressed as follows:

[0069]

[0070] Among them, represents the lower limit of the active output of the j-th virtual power plant output unit group of the n m th network framework of the m-th power distribution grid level, represents the upper limit of the active output of the j-th virtual power plant output unit group of the n m th network framework of the m-th power distribution grid level, represents the lower limit of the reactive output of the j-th virtual power plant output unit group of the n m th network framework of the m-th power distribution grid level, ​Represents the nth level of the m-th distribution network level m The upper limit of reactive power output of the j-th virtual power plant output unit group in the grid structure.

[0071] In step S3, please refer to Figure 1 In step S3, the collected data of each distribution network level are input, and the power flow of each distribution network level is calculated independently starting from the lowest voltage level. The power injected at the head end of the low voltage level distribution network level is equivalent to the node load of the high voltage level distribution network level, and the power flow operation status of each distribution network level is output.

[0072] Specifically, step S3 includes the following steps:

[0073] In step S31, input the collected data from each distribution network level.

[0074] In step S32, the distribution network hierarchy is divided and initialized, setting the distribution network hierarchy m=1, that is, starting from the distribution network hierarchy with the lowest voltage level; the network structure n of each distribution network hierarchy is set. m =min{n m That is, start from the grid with the smallest sorting mark.

[0075] In step S33, random values ​​are assigned to the variables of the virtual power plant output cost optimization model, and random values ​​are assigned to the virtual power plant output unit group within the upper and lower limit constraints of the virtual power plant output unit group.

[0076] In step S34, the nth node of the lower-level distribution network level m is... m Each grid structure performs independent power flow calculations, as shown below:

[0077]

[0078]

[0079] in, Represents the nth level of the m-th distribution network level m The current flowing on the branch connecting two nodes ij in a network structure. Represents the nth level of the m-th distribution network level m The corresponding active power flowing on the branch connecting two nodes of a network structure. Represents the nth level of the m-th distribution network level m The corresponding reactive power flowing on the branch connecting two nodes of a grid structure; Represents the nth level of the m-th distribution network level m The voltage of node i in the network structure, Represents the nth level of the m-th distribution network level m The voltage at node j of the network structure, active power of distributed generator unit group of node j of the n m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m th grid of the m m th grid of the m

[0080] Specifically, when m = 1, the node load of node i of the n1th grid of the power distribution grid level 1 is composed of the fixed node load , and there is no equivalent load at this time; when m ≥ 2, the equivalent load is calculated

[0081] In step S35, the first-end injected power of the n m th grid of the lower power distribution grid level m is equivalent to the node load of the corresponding n m+1 th grid of the upper power distribution grid level m+1, which is represented as follows:

[0082]

[0083] wherein, active power injected by the first end of the n m th grid of the m th grid of the m mreactive power injected by the first end of the grid, represents the n m+1 equivalent active load of the i represents the n m+1 equivalent reactive load of the i

[0084] As an example, the grid of each power distribution network level is associated by the tie-line power transmission, the injected power of the first end of the lower grid is equivalent to the node load of the upper grid, the cross-level power flow coupling is realized, the grids of each power distribution network level are associated, the influence of the lower power distribution network on the upper power distribution network is accurately reflected, and the top-down multi-voltage level coordination is realized.

[0085] In step S36, it is judged whether the power distribution network level number m is equal to the highest power distribution network level number M. If not, m = m + 1 is set, and step S37 is entered. If yes, step S38 is entered.

[0086] In step S37, the power flow calculation is performed on the n m+1 th grid of the upper power distribution network level m + 1, and step S36 is returned.

[0087] Specifically, when the power flow calculation is performed on the n m+1 th grid of the upper power distribution network level m + 1, the node load of the node i of the n m+1 th grid of the upper power distribution network level m + 1 is composed of the fixed node load and the equivalent node load .

[0088] The power flow calculation is performed on the n m+1 th grid of the upper power distribution network level m + 1, and step S36 is returned.

[0089]

[0090] wherein, represents the current flowing on the branch connected between the i m+1 th grid of the upper power distribution network level m + 1, represents the corresponding active power flowing on the branch connected between the i m+1 th grid of the upper power distribution network level m + 1, represents the corresponding reactive power flowing on the branch connected between the i m+1 th grid of the upper power distribution network level m + 1; represents the voltage of the node i of the n m+1 th grid of the upper power distribution network level m + 1, represents the nm+1 the voltage of the node j of the grid, the n m+1 the branch resistance of the branch connected between the two nodes i and j of the grid, the n m+1 the branch reactance of the branch connected between the two nodes i and j of the grid, the n m+1 the active power output of the distributed power unit group of the node j of the grid, the n m+1 the reactive power output of the distributed power unit group of the node j of the grid, the n m+1 the active power output of the virtual power plant output unit group of the node j of the grid, the n m+1 the reactive power output of the virtual power plant output unit group of the node j of the grid, the n m+1 the active power load of the node load of the node j of the grid, the n m+1 the reactive power load of the node load of the node j of the grid, the n m+1 the equivalent reactive power load of the node load of the node i of the grid, the n m+1 the equivalent reactive power load of the node load of the node i of the grid, the n m+1 the corresponding active power flowing on the branch connected between the two nodes j and k of the grid, the n m+1 the corresponding reactive power flowing on the branch connected between the two nodes j and k of the grid.

[0091] In step S38, the branch power flow operation of each grid of each power grid level is output, including: the branch current of each power grid level, the node voltage of each power grid level, the branch power of each power grid level.

[0092] In step S4, please refer to Figure 1In step S4, establish the power flow verification constraint model for each distribution network level, perform power flow verification for each distribution network level based on the power flow operation status of each distribution network level, and determine whether the power flow of each distribution network level meets the safe operation verification constraint. If yes, proceed to step S5; otherwise, proceed to step S6.

[0093] As an example, the branch currents, node voltages, and branch power of each branch of each grid at all distribution network levels are received to satisfy the safety operation verification constraint as the second constraint condition of the virtual power plant output cost optimization model.

[0094] Specifically, the safety operation verification constraints include: voltage safety constraints and branch power and current safety operation constraints.

[0095] As an example, voltage safety constraints are represented as follows:

[0096]

[0097] in, Represents the nth level of the m-th distribution network level m The lower voltage limit of node i in a network structure. Represents the nth level of the m-th distribution network level m The upper limit of voltage for node i of a network structure.

[0098] The safety operating constraints for branch power and current are expressed as follows:

[0099]

[0100] in, Represents the nth level of the m-th distribution network level m The upper limit of the current flowing on the branch connecting two nodes ij in a network structure. Represents the nth level of the m-th distribution network level m Apparent power on the branch connecting two nodes of a network structure; Represents the nth level of the m-th distribution network level m Safety margin factor for branch power of each grid structure; Represents the nth level of the m-th distribution network level m The apparent power limit on the branch connecting two nodes of a network structure.

[0101] In step S5, please refer to Figure 1 In step S5, an optimization algorithm is used to solve the virtual power plant output cost optimization model to obtain the lowest total output cost of the virtual power plant in the distribution network and the corresponding output value of the virtual power plant output unit group at each distribution network level.

[0102] As an example, after the objective function and the constraint conditions of the virtual power plant output cost optimization model are established, the optimization algorithm is called to solve the virtual power plant output cost optimization model under the condition of meeting the first constraint condition and the second constraint condition.

[0103] In an embodiment of the present application, the genetic algorithm is used as the optimization algorithm to solve the virtual power plant output cost optimization model. The termination conditions of the genetic algorithm include:

[0104] The maximum number of iterations of the genetic algorithm is reached to stop iteration;

[0105] The change rate of the objective function of the virtual power plant output cost optimization model after continuous multiple iterations is less than the threshold value ∈, that is, the iteration is stopped after convergence to ∈; wherein the accuracy of the threshold value ∈ is selected according to the actual situation.

[0106] As an example, after the optimization algorithm is solved, the output results of the virtual power plant output cost optimization model include: the lowest total cost OBJ of the virtual power plant output eco , the active power output of the virtual power plant output unit group of each distribution network level network frame The reactive power output of the virtual power plant output unit group of each distribution network level network frame

[0107] In step S6, please refer to S6 step in Figure 1 , reassign the collected data of each distribution network level, and return to step S2.

[0108] As an example, if any network frame of any distribution network level does not meet the safety operation verification constraint, the virtual power plant output unit group is revalued, and the step S2 is returned to perform a new round of optimization on the network frame power flow of each distribution network level.

[0109] The present application also provides a power distribution network dispatching system, please refer to Figure 4 , Figure 4 The module diagram of the power distribution network dispatching system provided by the present application, the power distribution network dispatching system provided by the present application is used to execute the above-mentioned power distribution network dispatching method, which includes: a virtual power plant output cost optimization module 41, the virtual power plant output cost optimization module 41 includes each distribution network level power flow calculation unit 411 and each distribution network level power flow verification unit 412; each distribution network level power flow calculation unit 411 is connected with each distribution network level power flow verification unit 412.

[0110] As an example, the virtual power plant output cost optimization module 41 is configured to collect data of each power distribution network level, set the lowest total cost of virtual power plant output as an objective function, construct a virtual power plant output cost optimization model, and solve the virtual power plant output cost optimization model by using an optimization algorithm under the condition of meeting the constraint condition to obtain the lowest total cost of virtual power plant output of the power distribution network and corresponding virtual power plant output unit group output values of each power distribution network level.

[0111] As an example, the power flow calculation unit 411 of each power distribution network level is configured to input the collected data of each power distribution network level, independently calculate the power flow of each power distribution network level in turn from the power distribution network level of the lowest voltage level, equivalently set the first end injection power of the power distribution network level of the low voltage level as the node load of the power distribution network level of the high voltage level, and output the power flow operation of each power distribution network level.

[0112] As an example, the power flow verification unit 412 of each power distribution network level is configured to establish a power flow verification constraint model of each power distribution network level, perform power flow verification of each power distribution network level according to the power flow operation of each power distribution network level, judge whether the power flow of each power distribution network level meets the safety operation verification constraint, if yes, continue the virtual power plant output cost optimization; if not, reassign the collected data of each power distribution network level and perform a new round of virtual power plant output cost optimization.

[0113] The application also provides a computer program product comprising a computer program which, when executed by a processor, implements the steps of the power distribution network dispatching method described above.

[0114] The power distribution network dispatching method and system, and the computer program product provided by the application consider inverse-level dynamic coupling modeling of grid connection of new energy and other new type power generation units, accurately quantify the cascading effect of grid connection of large-scale new energy and other new type power generation units on the power distribution network, ensure that the power of all lines is within the dynamic safety limit, realize accurate analysis of cross-level power distribution networks, and solve the problem of power flow fluctuation of multi-voltage level power distribution networks caused by the access of distributed new energy and other new type power generation units, thereby affecting the stability of power flow operation and cross-level coupling. A multi-dimensional safety checking system comprehensively guarantees the operation safety. Meanwhile, the safety operation verification constraint and the economic optimization objective function of the lowest total cost of virtual power plant output are uniformly modeled, the configuration of the virtual power plant output unit group is optimized, the fluctuation of new energy and other new type power generation units is coordinated, the goal of optimal operation cost is achieved, and an integrated solution for dynamic safety and economic dispatching of new energy and other new type power generation unit power distribution networks is provided, which provides high-reliability and high-economy dispatching support for new type power systems.

[0115] Although the present application has been disclosed with reference to the embodiments above, it is not intended to limit the present application, and any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application is defined by the appended claims.

Claims

1. A power distribution network dispatching method, characterized by, Comprising, Step S1: dividing the power distribution network into multiple power distribution network levels according to voltage levels, each power distribution network level comprising multiple network frames; Step S2: collecting data of each power distribution network level, setting the lowest total cost of virtual power plant output as the objective function, and constructing a virtual power plant output cost optimization model; Step S3: inputting the collected data of each power distribution network level, starting from the lowest voltage level of the power distribution network level, and sequentially and independently calculating the power flow of each power distribution network level, the injected power at the head of the power distribution network level of the low voltage level being equivalent to the node load of the power distribution network level of the high voltage level, and outputting the power flow operation of each power distribution network level; Step S4: establishing a power flow checking constraint model for each power distribution network level, performing power flow checking for each power distribution network level according to the power flow operation of each power distribution network level, and determining whether the power flow of each power distribution network level meets the safety operation checking constraint, if yes, entering step S5, if no, entering step S6; Step S5: solving the virtual power plant output cost optimization model by using an optimization algorithm to obtain the lowest total cost of the virtual power plant output of the power distribution network and the corresponding output values of each virtual power plant output unit group of each power distribution network level; Step S6: reassigning the collected data of each power distribution network level and returning to step S2.

2. The power distribution grid scheduling method of claim 1, wherein, The collected data of each power distribution network level includes: the active load and reactive load of the node load of each power distribution network level network frame, the active output and reactive output of the distributed power unit output of each power distribution network level network frame, the active output and reactive output of the virtual power plant output unit group output of each power distribution network level network frame, the virtual power plant output unit group quotation, and the branch resistance and reactance of each power distribution network level network frame.

3. The power distribution grid scheduling method of claim 2, wherein, The objective function of the virtual power plant output cost optimization model is represented as follows: wherein, represents the lowest total cost of virtual power plant output, represents the virtual power plant output unit group offer of node i of the mth layer distribution network level th network frame; represents the virtual power plant output unit group active power output of node i of the mth layer power grid th network frame.

4. The power distribution grid scheduling method of claim 2, wherein, The constraint conditions of the virtual power plant output cost optimization model include: the power flow checking constraint of each power distribution network level and the upper and lower limit constraint of the virtual power plant output unit group processing; the upper and lower limit constraint of the virtual power plant output unit group processing is represented as follows: in, The m-th level of the distribution network represents the m-th level. The lower limit of active power output of the virtual power plant output unit group at node j of the network structure. Represents the m-th level of the distribution network. The upper limit of active power output of the virtual power plant output unit group at node j of the network structure. Represents the m-th level of the distribution network. The lower limit of reactive power output of the virtual power plant output unit group at node j of the network structure. The m-th level of the distribution network represents the m-th level. The upper limit of reactive power output of the virtual power plant output unit group of node j of the network structure; Represents the m-th level of the distribution network. The active power output of the virtual power plant output unit group at node j of the network structure. The m-th level of the distribution network represents the m-th level. The reactive power output of the virtual power plant output unit group at node j of the network structure.

5. The power distribution grid scheduling method of claim 3, wherein, Step S3 specifically includes: Input the collected data of each power distribution network level; Perform power distribution network level division and initialization, set the power distribution network level from the lowest voltage level of the power distribution network level; set the network frame of each power distribution network level from the network frame with the smallest sorting mark; Randomly assign the virtual power plant output cost optimization model variables within the upper and lower limit constraint of the virtual power plant output unit group processing; Independently calculate the power flow of each network frame of the power distribution network level in turn; The injected power at the head of the network frame of the power distribution network level of the low voltage level is equivalent to the node load of the network frame of the power distribution network level of the high voltage level; Determine whether the number of power distribution network levels is equal to the number of the highest power distribution network level, if not, increase the voltage level of the power distribution network level by 1, and perform power flow calculation on each network frame of the power distribution network level of the high voltage level, and continue to determine whether the number of power distribution network levels is equal to the number of the highest power distribution network level; if yes, output the branch power flow operation of each network frame of all power distribution network levels, including: the branch current of each power distribution network level, the node voltage of each power distribution network level, and the branch power of each power distribution network level.

6. The power distribution grid scheduling method of claim 5, wherein, Independently calculate the power flow of each network frame of a certain power distribution network level, which is represented as follows: in, The m-th level of the distribution network represents the m-th level. The current flowing on the branch connecting two nodes ij in a network structure. The m-th level of the distribution network represents the m-th level. The corresponding active power flowing on the branch connecting two nodes of a network structure. The m-th level of the distribution network represents the m-th level. The corresponding reactive power flowing on the branch connecting two nodes of a grid structure; The m-th level of the distribution network represents the m-th level. The voltage of node i in the network structure, The m-th level of the distribution network represents the m-th level. The voltage at node j of the network structure, The m-th level of the distribution network represents the m-th level. The branch resistance on the branch connecting two nodes ij in a network structure. The m-th level of the distribution network represents the m-th level. The branch reactance of the branch connected to the two nodes of the network structure. The m-th level of the distribution network represents the m-th level. The active power output of the distributed power unit at node j of the network structure. The m-th level of the distribution network represents the m-th level. The reactive power output of the distributed power generation unit at node j of the network structure. The m-th level of the distribution network represents the m-th level. The active power output of the virtual power plant output unit group at node j of the network structure. The m-th level of the distribution network represents the m-th level. The reactive power output of the virtual power plant output unit group at node j of the network structure. The m-th level of the distribution network represents the m-th level. The active load of node j in a network structure. The m-th level of the distribution network represents the m-th level. The reactive load of node j in a network structure. The m-th level of the distribution network represents the m-th level. The equivalent active load of node i in a network structure. The m-th level of the distribution network represents the m-th level. The equivalent reactive load of node i in a network structure. The m-th level of the distribution network represents the m-th level. The corresponding active power flowing on the branch connecting two nodes of the JK grid structure. The m-th level of the distribution network represents the m-th level. The corresponding reactive power flowing on the branch connecting the jk two nodes of the grid.

7. The power distribution grid scheduling method of claim 5, wherein, The low-voltage level power distribution network level network frame first end injected power is equivalent to the corresponding high one voltage level power distribution network level network frame node load, and is represented as follows: in, The m-th level of the distribution network represents the m-th level. The active power injected at the beginning of each grid structure The m-th level of the distribution network represents the m-th level. The reactive power injected at the beginning of the grid structure This represents the (m+1)th level of the distribution network. The equivalent active load of the i-th node of the network structure This represents the (m+1)th level of the distribution network. The equivalent reactive load of the i-th node of the network structure.

8. The power distribution grid scheduling method of claim 2, wherein, The safe operation verification constraints include: voltage safety constraints, branch power and current safe operation constraints; The voltage safety constraints are represented as follows: wherein, Vmin,m,i represents a lower voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy, Vmax,m,i represents an upper voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy; Vmin,m,i represents a lower voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy, Vmax,m,i represents an upper voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy; Vmin,m,i represents a lower voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy, Vmax,m,i represents an upper voltage limit of a node i of a grid rack of an mth level of a power distribution grid hierarchy The branch power and current safe operation constraints are represented as follows: in, The m-th level of the distribution network represents the m-th level. The upper limit of the current flowing on the branch connecting two nodes ij in a network structure. The m-th level of the distribution network represents the m-th level. Apparent power on the branch connecting two nodes of a network structure; The m-th level of the distribution network represents the m-th level. Safety margin factor for branch power of each grid structure; The m-th level of the distribution network represents the m-th level. The apparent power limit on the branch connecting two nodes of a network structure; The m-th level of the distribution network represents the m-th level. The current flowing on the branch connecting two nodes ij in a network structure. The m-th level of the distribution network represents the m-th level. The corresponding active power flowing on the branch connecting two nodes of a network structure. The m-th level of the distribution network represents the m-th level. The corresponding reactive power flowing on the branch connecting two nodes ij of a grid structure.

9. A power distribution network dispatching system for performing a power distribution network dispatching method according to any one of claims 1 to 8. Including: The virtual power plant output cost optimization module includes each power distribution network level power flow calculation unit and each power distribution network level power flow verification unit. Each power distribution network level power flow calculation unit is connected with each power distribution network level power flow verification unit.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the power distribution network dispatching method in any one of claims 1-8.

Images