CN104810829B - A kind of network structure simplified process method of power distribution network reconfiguration - Google Patents

Abstract

The present invention is complicated for distribution net work structure, the solving result time is long during reconstruct, the slow-footed problem of Load flow calculation, a kind of network structure simplified process method of power distribution network reconfiguration is provided, during using power distribution network reconfiguration the characteristics of network structure, operable switch is used as border using in network structure, the simplified topological structure that network structure is reduced to be made up of some regions, in the case where radial networks topological constraints are met, it is quickly generated topology reconstruction strategy, and in topology reconstruction strategy of every generation, when carrying out a trend simplification calculating, calculating speed is improved using trend simplified model, quickly obtain optimum network structure, ensure to carry out real-time optimal control to power distribution network.

Description

Network structure simplification processing method for power distribution network reconstruction

Technical Field

The invention belongs to the technical field of power distribution system automation, and particularly relates to a network structure simplification processing method for power distribution network reconstruction.

Background

The power distribution network reconstruction is an important means for optimizing the operation of a power distribution system and is an important content of power distribution automation research. The distribution network has the characteristic of open-loop operation in a closed-loop design, and a large number of section switches for isolating faults and a small number of tie switches for providing optional paths are often configured in the network. The states of the switches are changed according to different load conditions, so that the purpose of adjusting the running state of the network is achieved. The power distribution network reconstruction aims at balancing network load, eliminating operation risk, reducing network loss and reducing operation cost, and under the condition of meeting radial network topology constraint, power flow equation constraint, node voltage constraint and switching action frequency constraint, the network structure of the power distribution network is adjusted, power flow distribution in the power distribution network is improved, and the network operation state is optimized. Therefore, power distribution network reconfiguration is an important means to improve power distribution system reliability, safety, and economy.

The basis of the power distribution network reconstruction is that the power distribution network flow analysis is carried out, the states of all switches in the network are different, so that the network structures are different, and through the power flow analysis of different network structures, when the objective function obtains the global optimum, the switch states in the network structures are considered to be the most reasonable. However, the network structure is complex, the load flow calculation needs repeated iteration, and the calculation time is long. Therefore, how to simplify the network structure, improve the tidal current operation speed, and quickly optimize the network structure becomes a problem to be solved urgently in network reconstruction.

Disclosure of Invention

Aiming at the problems of complex structure of a power distribution network, long time of solving results and low power flow calculation speed during reconstruction, the invention provides a simplified processing method of a power distribution network reconstructed network structure.

In order to achieve the purpose of the invention, the invention adopts the following technical scheme:

the invention provides a network structure simplification processing method for power distribution network reconstruction, which comprises the following steps:

step 1: carrying out region division and topology simplification on a network structure of the power distribution network to obtain a simplified topology structure;

step 2: reconstructing the simplified topological structure to generate a topological reconstruction strategy, and reducing and simplifying the topological reconstruction strategy;

and step 3: and carrying out forward-backward substitution power flow simplified calculation on the restored and simplified network structure, comparing and analyzing a topology reconstruction strategy, and selecting an optimal network structure.

Before carrying out region division and topology simplification on a network structure of a power distribution network, the method comprises the following steps:

(1) nodes, branches and switches in the power distribution network are numbered respectively, namely node numbering is carried out on load nodes and power supply nodes in the nodes respectively, branch numbering is carried out on branches connected with adjacent nodes, section switches and interconnection switches in the switches are numbered in a switch mode, and a branch-node description matrix B is generated and is an n-row matrix, and the n-row matrix is expressed as follows:

wherein n is the number of branches, b_n,1Numbering the branches, b_n,2、b_n,3Numbering the two end nodes of the branch connection, respectively, b_n,4Is the resistance of the branch, b_n,5Is the reactance of a branch, b_n,6The branch type comprises a branch containing a tie switch, a branch containing a section switch and a branch connecting adjacent nodes;

the load nodes form a load node matrix S, which is an m-row matrix, represented as:

wherein m is the number of load nodes, s_m,1Numbering load nodes, s_m,2、s_m,3The active power and the reactive power of the load node are respectively;

the power nodes form a power node matrix E, which is an s-column matrix, represented as:

E＝[e₁e₂… e_s]^T(3)

where s is the number of power supply nodes, e_sIs the s-th power supply node;

(2) and according to the branch-node description matrix B, the tail branches are contracted to the trunk and are approximately processed into equivalent nodes, namely, the total load of the contained branch points and the approximate loss on the branches are used for replacing the load size of the equivalent nodes, the number of the nodes is reduced, and meanwhile, the branch-node description matrix B is updated.

In the step 1, according to the position of an operable switch in the power distribution network, the nodes in the area are replaced by the areas, and the area division and topology simplification are completed on the network structure, so that the simplified topology structure is obtained.

According to the operable switch position and the branch-node description matrix B in the power distribution network, the area division and topology simplification are carried out on the network structure by adopting a breadth-first search method, and the method specifically comprises the following steps:

step 1-1: marking a node as a search starting point, and putting the node into a variable storage matrix Q;

step 1-2: finding a first node Q of a connected variable memory matrix Q in a branch-node description matrix B₁And searching the branch which does not contain the switch and is not marked to be searched, and loading a node q at the other end of the branch₂Sequentially putting the nodes in a variable storage matrix Q and simultaneously aiming at the nodes Q₂Marking and reserving branch numbers of the branches and numbers of two end nodes thereof in the area description matrix Z_lWherein l is the number of the region, 1,2, … zone, zone is the number of the region, and the region description matrix Z_lEach row stores branch information and marks the branches; region description matrix Z_lIs a u-row matrix, which is represented as:

wherein u is the number of branches contained in the region, z_u,1Numbering the branches in the region, z_u,2、z_u,3Numbering the nodes at both ends of the branch in the area, z_u,4Is the resistance of the branch in this region, z_u,5Is the reactance of a branch in this region, z_u,6、z_i,7The load of the nodes at the two ends of the branch in the area is obtained;

step 1-3: and (5) circulating the step (1-2) until all the AND nodes q are found₁Adjacent nodes without switches in the branches store all the found nodes in a variable storage matrix Q in sequence, and all the corresponding branch information is stored in Z in sequence_lThen, storing the variable in the second node Q of the matrix Q₂Modified as q₁；

Step 1-4: returning to the step 1-2 until the connection search of all nodes in the variable storage matrix Q is completed, namely, the search and the storage of all branches and nodes of a certain area are completed, updating the area number l to l +1, clearing the variable storage matrix Q, and searching unmarked nodes as the nodes Q₁Putting a variable storage matrix Q;

step 1-5: returning to the step 1-2 until all the nodes are marked, and at the moment, dividing the network structure into a plurality of areas;

step 1-6: checking all branches, searching unmarked branches, and obtaining a region adjacency matrix C of nbian rows as the unmarked branches contain switches, namely the edges connecting each region, and the expression is as follows:

wherein, c_nbian,1Is the edge of the connecting region, c_nbian,2、c_nbian,3Respectively the number of the two regions to which the edge is connected, c_nbian,4Numbering the branch corresponding to the edge, c_nbian,5、c_nbian,6Numbering nodes at two ends of a branch corresponding to the edge, namely boundary nodes of the region;

step 1-7: node d at two ends of branch corresponding to opposite sides₁、d₂Searching to find the node d₁、d₂Respectively marking the branch, and simultaneously storing branch numbers, node numbers, the numbers of the areas to which the branch belongs and the numbers of the area edges into an area adjacency matrix C;

step 1-8: and (5) circulating the steps 1-7 until all branches are marked, and finding the relation among the areas.

In the step 2, a topology reconstruction strategy is generated by using the adjacency relation between the regions, the topology reconstruction strategy is restored according to the corresponding relation between the regions and the nodes, and the restored network structure is simplified by using a power flow simplification model.

The step 2 specifically comprises the following steps:

step 2-1: reconstructing the simplified topological structure by adopting an artificial intelligence method according to the adjacency relation between the regions to generate a topological reconstruction strategy;

step 2-2: judging whether the generated topology reconstruction strategy is an island or a ring network according to the characteristics of the radial structure of the power distribution network and the power supply of the single power supply, if so, returning to the step 2-1, and regenerating the topology reconstruction strategy; otherwise, executing the step 2-3;

step 2-3: restoring the topological structure reconstructed through the topological reconstruction strategy by using the corresponding relation between the region and the node;

step 2-4: and simplifying the restored network structure by using the power flow simplification model.

In 2-3, the connection relation between each region is determined according to the generated topology reconstruction strategy, and then the corresponding node and branch are found through the region adjacency matrix C, combined with Z₁、Z₂、…、Z_l、…、Z_nzoneAnd the internal network structure can obtain the whole power distribution network structure, and the restoration of the topological structure reconstructed through the topological reconstruction strategy is completed.

In the simplified power flow model of step 2-4, for any feeder segment with multiple branches, when the power flow direction is from the head end node A of the feeder segment to the tail end node B, the phase voltage drop between the head end node A and the tail end node B is usedIt shows, as follows:

wherein N is the number of nodes on the feeder section, L_iThe length of the ith branch is the length of the ith branch,the phase voltage at the head end node a on the feeder section,for the complex power of node t, the symbol denotes the conjugate;

assuming that the total length of the feeder line section is L, assuming that the feeder line section is a uniform conductor, r and x respectively represent resistance and reactance of the feeder line section in unit length, the voltage drop of the phase voltage from the head end node A to the equivalent node DAnd voltage drop of phase voltage from node D to node BRespectively expressed as:

wherein,is the complex power of equivalent node D, L_ADThe length of a branch from a head-end node A to an equivalent node D;

the combined formulae (6) to (8) can be given as follows:

when the power flow direction is from the tail end node B to the head end node A on the feeder segment, the following steps are provided:

wherein,phase voltage of tail end node B on feeder line section，L_DBIs the branch length, L, from the equivalent node D to the head end node A_i+1The length of the (i + 1) th branch;

due to L_AD+L_DBL, available as:

the step 3 specifically comprises the following steps:

step 3-1: carrying out forward-pushing and backward-replacing power flow simplified calculation on the restored and simplified network structure, and calculating a reconstruction index according to a power flow analysis result;

step 3-2: comparing and analyzing each topology reconstruction strategy according to the reconstruction index, judging whether the network structure corresponding to the topology reconstruction strategy is the optimal network structure meeting the reconstruction condition, if so, selecting the network structure as the optimal network structure, and simultaneously outputting the network structure and the reconstruction index; otherwise, returning to the step 2-1 to regenerate the topology reconstruction strategy.

The step 3-1 specifically comprises the following steps:

step 3-1-1: carrying out forward-pushing back to replace the power flow simplified calculation on the restored and simplified network structure to obtain the A-phase voltage of the head-end node of the feeder line section in the power flow simplified modelPhase voltage of tail node BAnd the phase voltage of the equivalent node D

Step 3-1-2: will be provided withAndperforming load flow simplified calculation on the network structure as a known quantity, carrying out forward recursion from a tail end node of the network structure, judging whether a node to be solved belongs to a T contact, if not, executing a step 3-1-3, and if so, executing a step 3-1-4;

step 3-1-3: when the node to be solved does not belong to the T contact, calculating the branch loss of the tail end node kIt is expressed as:

wherein L is_kIs the branch length of the tail-end node k,the phase voltage at the tail-end node k,for the total power flowing through the tail end node k, P represents the total power, and L represents the loss;

thus, the total power flowing through node k-1Expressed as:

wherein,is the complex power of node k-1;

phase voltage of node k-1Expressed as:

step 3-1-4: when the node to be solved belongs to the T joint, because recursion is carried out according to the reverse direction of the tide direction, nodes and branches on adjacent feeder line sections at the downstream of the tail end node k are known, and the total power flowing through the tail end node k is calculatedComprises the following steps:

the theta is a set of all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction; v represents all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction;the branch loss on the v-th downstream feeder line adjacent to the node k is shown, wherein L represents the loss, and kv is the v-th downstream feeder line segment adjacent to the tail end node k;the total power passed by the tail-end node of the downstream feeder end adjacent to node k, P represents the total power,is the complex power of node k;

step 3-1-5: the bus loss of the computing network structure is as follows:

wherein,in order to account for the bus loss of the network architecture,for the loss of a feeder segment w, λ is the set of all feeder segments, and w is the feeder segment belonging to the set λ.

Compared with the prior art, the invention has the beneficial effects that:

1) according to the network structure characteristics when the topological structure is reconstructed, the network structure is divided into areas, the network topological structure is simplified, the efficiency of generating a topological reconstruction strategy can be improved, and meanwhile, the network topology can be quickly restored and simplified;

2) after the topology reconstruction strategy meeting the radial network is obtained, the load on the feeder terminal of the power distribution network is equivalently processed, the network topology structure is effectively simplified, and the node voltage of the simplified network can be quickly obtained by adopting forward-backward flow simplified calculation;

3) the voltages of the head end node and the tail end node of the simplified equivalent model and the equivalent node are used as known quantities, and the load flow calculation is performed on the non-simplified network again to obtain the load flow distribution of the whole network, so that the load flow calculation speed is increased, and the optimal network structure can be solved quickly.

Drawings

Fig. 1 is a flowchart of a simplified processing method for network structure reconfiguration of a power distribution network according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1, the present invention provides a network structure simplification processing method for power distribution network reconfiguration, including the following steps:

step 1: carrying out region division and topology simplification on a network structure of the power distribution network to obtain a simplified topology structure;

step 2: reconstructing the simplified topological structure to generate a topological reconstruction strategy, and reducing and simplifying the topological reconstruction strategy;

and step 3: and carrying out forward-backward substitution power flow simplified calculation on the restored and simplified network structure, comparing and analyzing a topology reconstruction strategy, and selecting an optimal network structure.

Before carrying out region division and topology simplification on a network structure of a power distribution network, the method comprises the following steps:

(1) nodes, branches and switches in the power distribution network are numbered respectively, namely node numbering is carried out on load nodes and power supply nodes in the nodes respectively, branch numbering is carried out on branches connected with adjacent nodes, section switches and interconnection switches in the switches are numbered in a switch mode, and a branch-node description matrix B is generated and is an n-row matrix, and the n-row matrix is expressed as follows:

wherein n is the number of branches, b_n,1Numbering the branches, b_n,2、b_n,3Numbering the two end nodes of the branch connection, respectively, b_n,4Is the resistance of the branch, b_n,5Is the reactance of a branch, b_n,6The branch type comprises a branch containing a tie switch, a branch containing a section switch and a branch connecting adjacent nodes;

the load nodes form a load node matrix S, which is an m-row matrix, represented as:

wherein m is the number of load nodes, s_m,1Numbering load nodes, s_m,2、s_m,3The active power and the reactive power of the load node are respectively;

the power nodes form a power node matrix E, which is an s-column matrix, represented as:

E＝[e₁e₂… e_s]^T(3)

where s is the number of power supply nodes, e_sIs the s-th power supply node;

(2) and according to the branch-node description matrix B, the tail branches are contracted to the trunk and are approximately processed into equivalent nodes, namely, the total load of the contained branch points and the approximate loss on the branches are used for replacing the load size of the equivalent nodes, the number of the nodes is reduced, and meanwhile, the branch-node description matrix B is updated.

In the step 1, according to the position of an operable switch in the power distribution network, the nodes in the area are replaced by the areas, and the area division and topology simplification are completed on the network structure, so that the simplified topology structure is obtained.

According to the operable switch position and the branch-node description matrix B in the power distribution network, the area division and topology simplification are carried out on the network structure by adopting a breadth-first search method, and the method specifically comprises the following steps:

step 1-1: marking a node as a search starting point, and putting the node into a variable storage matrix Q;

step 1-2: finding a first node Q of a connected variable memory matrix Q in a branch-node description matrix B₁And searching the branch which does not contain the switch and is not marked to be searched, and loading a node q at the other end of the branch₂Sequentially putting the nodes in a variable storage matrix Q and simultaneously aiming at the nodes Q₂Marking and reserving branch numbers of the branches and numbers of two end nodes thereof in the area description matrix Z_lWherein l is the number of the region, 1,2, … zone, zone is the number of the region, and the region description matrix Z_lEach row stores branch information and marks the branches; region description matrix Z_lIs a u-row matrix, which is represented as:

wherein u is the number of branches contained in the region, z_u,1Numbering the branches in the region, z_u,2、z_u,3Numbering the nodes at both ends of the branch in the area, z_u,4Is the resistance of the branch in this region, z_u,5Is the reactance of a branch in this region, z_u,6、z_i,7The load of the nodes at the two ends of the branch in the area is obtained;

step 1-3: and (5) circulating the step (1-2) until all the AND nodes q are found₁Adjacent nodes without switches in the branches store all the found nodes in a variable storage matrix Q in sequence, and all the corresponding branch information is stored in Z in sequence_lThen, storing the variable in the second node Q of the matrix Q₂Modified as q₁；

Step 1-4: returning to the step 1-2 until the connection search of all nodes in the variable storage matrix Q is completed, namely, the search and the storage of all branches and nodes of a certain area are completed, updating the area number l to l +1, clearing the variable storage matrix Q, and searching unmarked nodes as nodesq₁Putting a variable storage matrix Q;

step 1-5: returning to the step 1-2 until all the nodes are marked, and at the moment, dividing the network structure into a plurality of areas;

step 1-6: checking all branches, searching unmarked branches, and obtaining a region adjacency matrix C of nbian rows as the unmarked branches contain switches, namely the edges connecting each region, and the expression is as follows:

wherein, c_nbian,1Is the edge of the connecting region, c_nbian,2、c_nbian,3Respectively the number of the two regions to which the edge is connected, c_nbian,4Numbering the branch corresponding to the edge, c_nbian,5、c_nbian,6Numbering nodes at two ends of a branch corresponding to the edge, namely boundary nodes of the region;

step 1-7: node d at two ends of branch corresponding to opposite sides₁、d₂Searching to find the node d₁、d₂Respectively marking the branch, and simultaneously storing branch numbers, node numbers, the numbers of the areas to which the branch belongs and the numbers of the area edges into an area adjacency matrix C;

step 1-8: and (5) circulating the steps 1-7 until all branches are marked, and finding the relation among the areas.

In the step 2, a topology reconstruction strategy is generated by using the adjacency relation between the regions, the topology reconstruction strategy is restored according to the corresponding relation between the regions and the nodes, and the restored network structure is simplified by using a power flow simplification model.

The step 2 specifically comprises the following steps:

step 2-1: reconstructing the simplified topological structure by adopting an artificial intelligence method according to the adjacency relation between the regions to generate a topological reconstruction strategy;

step 2-2: judging whether the generated topology reconstruction strategy is an island or a ring network according to the characteristics of the radial structure of the power distribution network and the power supply of the single power supply, if so, returning to the step 2-1, and regenerating the topology reconstruction strategy; otherwise, executing the step 2-3;

step 2-3: restoring the topological structure reconstructed through the topological reconstruction strategy by using the corresponding relation between the region and the node;

step 2-4: and simplifying the restored network structure by using the power flow simplification model.

In 2-3, the connection relation between each region is determined according to the generated topology reconstruction strategy, and then the corresponding node and branch are found through the region adjacency matrix C, combined with Z₁、Z₂、…、Z_l、…、Z_nzoneAnd the internal network structure can obtain the whole power distribution network structure, and the restoration of the topological structure reconstructed through the topological reconstruction strategy is completed.

In the simplified power flow model of step 2-4, for any feeder segment with multiple branches, when the power flow direction is from the head end node A of the feeder segment to the tail end node B, the phase voltage drop between the head end node A and the tail end node B is usedIt shows, as follows:

wherein N is the number of nodes on the feeder section, L_iThe length of the ith branch is the length of the ith branch,the phase voltage at the head end node a on the feeder section,for the complex power of node t, the symbol denotes the conjugate;

assuming that the total length of the feeder line section is L, assuming that the feeder line section is a uniform conductor, r and x respectively represent resistance and reactance of the feeder line section in unit length, the voltage drop of the phase voltage from the head end node A to the equivalent node DAnd voltage drop of phase voltage from node D to node BRespectively expressed as:

wherein,is the complex power of equivalent node D, L_ADThe length of a branch from a head-end node A to an equivalent node D;

the combined formulae (6) to (8) can be given as follows:

when the power flow direction is from the tail end node B to the head end node A on the feeder segment, the following steps are provided:

wherein,is the phase voltage, L, of the tail node B on the feeder section_DBIs the branch length, L, from the equivalent node D to the head end node A_i+1The length of the (i + 1) th branch;

due to L_AD+L_DBL, available as:

the step 3 specifically comprises the following steps:

step 3-1: carrying out forward-pushing and backward-replacing power flow simplified calculation on the restored and simplified network structure, and calculating a reconstruction index according to a power flow analysis result;

step 3-2: comparing and analyzing each topology reconstruction strategy according to the reconstruction index, judging whether the network structure corresponding to the topology reconstruction strategy is the optimal network structure meeting the reconstruction condition, if so, selecting the network structure as the optimal network structure, and simultaneously outputting the network structure and the reconstruction index; otherwise, returning to the step 2-1 to regenerate the topology reconstruction strategy.

The step 3-1 specifically comprises the following steps:

step 3-1-1: carrying out forward-pushing back to replace the power flow simplified calculation on the restored and simplified network structure to obtain the A-phase voltage of the head-end node of the feeder line section in the power flow simplified modelPhase voltage of tail node BAnd the phase voltage of the equivalent node D

Step 3-1-2: will be provided withAndperforming load flow simplified calculation on the network structure as a known quantity, carrying out forward recursion from a tail end node of the network structure, judging whether a node to be solved belongs to a T contact, if not, executing a step 3-1-3, and if so, executing a step 3-1-4;

step 3-1-3: when the node to be solved does not belong to the T contact, calculating the branch loss of the tail end node kIt is expressed as:

wherein L is_kIs the branch length of the tail-end node k,the phase voltage at the tail-end node k,for the total power flowing through the tail end node k, P represents the total power, and L represents the loss;

thus, the total power flowing through node k-1Expressed as:

wherein,is the complex power of node k-1;

phase voltage of node k-1Expressed as:

step 3-1-4: when the node to be solved belongs to the T joint, because recursion is carried out according to the reverse direction of the tide direction, nodes and branches on adjacent feeder line sections at the downstream of the tail end node k are known, and the total power flowing through the tail end node k is calculatedComprises the following steps:

the theta is a set of all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction; v represents all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction;the branch loss on the v-th downstream feeder line adjacent to the node k is shown, wherein L represents the loss, and kv is the v-th downstream feeder line segment adjacent to the tail end node k;the total power passed by the tail-end node of the downstream feeder end adjacent to node k, P represents the total power,is the complex power of node k;

step 3-1-5: the bus loss of the computing network structure is as follows:

wherein,in order to account for the bus loss of the network architecture,for the loss of a feeder segment w, λ is the set of all feeder segments, and w is the feeder segment belonging to the set λ.

Finally, it should be noted that: the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalents to the specific embodiments of the present invention with reference to the above embodiments, and such modifications or equivalents without departing from the spirit and scope of the present invention are within the scope of the claims of the present invention as set forth in the claims.

Claims (9)

1. A network structure simplification processing method for power distribution network reconstruction is characterized by comprising the following steps: the method comprises the following steps:

step 1: carrying out region division and topology simplification on a network structure of the power distribution network to obtain a simplified topology structure;

step 2: reconstructing the simplified topological structure to generate a topological reconstruction strategy, and reducing and simplifying the topological reconstruction strategy;

and step 3: carrying out forward-backward substitution power flow simplified calculation on the restored and simplified network structure, comparing and analyzing a topology reconstruction strategy, and selecting an optimal network structure;

before carrying out region division and topology simplification on a network structure of a power distribution network, the method comprises the following steps:

(1) nodes, branches and switches in the power distribution network are numbered respectively, namely node numbering is carried out on load nodes and power supply nodes in the nodes respectively, branch numbering is carried out on branches connected with adjacent nodes, section switches and interconnection switches in the switches are numbered in a switch mode, and a branch-node description matrix B is generated and is an n-row matrix, and the n-row matrix is expressed as follows:

$B=\left[\begin{array}{cccccc}{b}_{1,1}& b_{1,2}& b_{1,3}& b_{1,4}& b_{1,5}& b_{1,6}\\ b_{2,1}& b_{2,2}& b_{2,3}& b_{2,4}& b_{2,5}& b_{2,6}\\ \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}\\ b_{n,1}& b_{n,2}& b_{n,3}& b_{n,4}& b_{n,5}& b_{n,6}\end{array}\right]---\left(1\right)$

wherein n is the number of branches, b_n,1Numbering the branches, b_n,2、b_n,3Numbering the two end nodes of the branch connection, respectively, b_n,4Is the resistance of the branch, b_n,5Is the reactance of a branch, b_n,6The branch type comprises a branch containing a tie switch, a branch containing a section switch and a branch connecting adjacent nodes;

the load nodes form a load node matrix S, which is an m-row matrix, represented as:

$S=\left[\begin{array}{ccc}{s}_{1,1}& s_{1,2}& s_{1,3}\\ s_{2,1}& s_{2,2}& s_{2,3}\\ \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}\\ s_{m,1}& s_{m,2}& s_{m,3}\end{array}\right]---\left(2\right)$

wherein m is the number of load nodes, s_m,1Numbering load nodes, s_m,2、s_m,3The active power and the reactive power of the load node are respectively;

the power nodes form a power node matrix E, which is an s-column matrix, represented as:

E＝[e₁e₂… e_s]^T(3)

where s is the number of power supply nodes, e_sIs the s-th power supply node;

(2) according to the branch-node description matrix B, the terminal branches are contracted to the trunk and are approximately processed into equivalent nodes; the total load of the included branch points and the approximate loss on the branch are used for replacing the load size of the equivalent node, the number of the nodes is reduced, and meanwhile, the branch-node description matrix B is updated.

2. The network structure simplification processing method for power distribution network reconstruction according to claim 1, characterized in that: in the step 1, according to the position of an operable switch in the power distribution network, the nodes in the area are replaced by the areas, and the area division and topology simplification are completed on the network structure, so that the simplified topology structure is obtained.

3. The network structure simplification processing method for power distribution network reconstruction according to claim 2, characterized in that: according to the operable switch position and the branch-node description matrix B in the power distribution network, the area division and topology simplification are carried out on the network structure by adopting a breadth-first search method, and the method specifically comprises the following steps:

step 1-1: marking a node as a search starting point, and putting the node into a variable storage matrix Q;

step 1-2: finding a first node Q of a connected variable memory matrix Q in a branch-node description matrix B₁And searching the branch which does not contain the switch and is not marked to be searched, and loading a node q at the other end of the branch₂Sequentially putting the nodes in a variable storage matrix Q and simultaneously aiming at the nodes Q₂Marking and reserving branch numbers of the branches and numbers of two end nodes thereof in the area description matrix Z_lWherein l is the number of the region, 1,2, … zone, zone is the number of the region, and the region description matrix Z_lEach row stores branch information and marks the branches; region description matrix Z_lIs a u-row matrix, which is represented as:

$Z_l=\left[\begin{array}{ccccccc}{z}_{1,1}& z_{1,2}& z_{1,3}& z_{1,4}& z_{1,5}& z_{1,6}& z_{1,7}\\ z_{2,1}& z_{2,2}& z_{2,3}& z_{2,4}& z_{2,5}& z_{2,6}& z_{2,7}\\ \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}\\ z_{u,1}& z_{u,2}& z_{u,3}& z_{u,4}& z_{u,5}& z_{u,6}& z_{u,7}\end{array}\right]---\left(4\right)$

wherein u is the number of branches contained in the region, z_u,1Numbering the branches in the region, z_u,2、z_u,3Numbering the nodes at both ends of the branch in the area, z_u,4Is the resistance of the branch in this region, z_u,5Is the reactance of a branch in this region, z_u,6、z_i,7The load of the nodes at the two ends of the branch in the area is obtained;

step 1-3: the step 1-2 is circulated until all the nodes are foundPoint q₁Adjacent nodes without switches in the branches store all the found nodes in a variable storage matrix Q in sequence, and all the corresponding branch information is stored in Z in sequence_lThen, storing the variable in the second node Q of the matrix Q₂Modified as q₁；

Step 1-4: returning to the step 1-2 until the connection search of all nodes in the variable storage matrix Q is completed, namely, the search and the storage of all branches and nodes of a certain area are completed, updating the area number l to l +1, clearing the variable storage matrix Q, and searching unmarked nodes as the nodes Q₁Putting a variable storage matrix Q;

step 1-5: returning to the step 1-2 until all the nodes are marked, and at the moment, dividing the network structure into a plurality of areas;

step 1-6: checking all branches, searching unmarked branches, and obtaining a region adjacency matrix C of nbian rows as the unmarked branches contain switches, namely the edges connecting each region, and the expression is as follows:

$C=\left[\begin{array}{cccccc}{c}_{1,1}& c_{1,2}& c_{1,3}& c_{1,4}& c_{1,5}& c_{1,6}\\ c_{2,1}& c_{2,2}& c_{2,3}& c_{2,4}& c_{2,5}& c_{2,6}\\ \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}\\ c_{nbian,1}& c_{nbian,2}& c_{nbian,3}& c_{nbian,4}& c_{nbian,5}& c_{nbian,6}\end{array}\right]---\left(5\right)$

wherein, c_nbian,1Is the edge of the connecting region, c_nbian,2、c_nbian,3Respectively the number of the two regions to which the edge is connected, c_nbian,4Numbering the branch corresponding to the edge, c_nbian,5、c_nbian,6Numbering nodes at two ends of a branch corresponding to the edge, namely boundary nodes of the region;

step 1-7: node d at two ends of branch corresponding to opposite sides₁、d₂Searching to find the node d₁、d₂Respectively marking the branch, and simultaneously storing branch numbers, node numbers, the numbers of the areas to which the branch belongs and the numbers of the area edges into an area adjacency matrix C;

step 1-8: and (5) circulating the steps 1-7 until all branches are marked, and finding the relation among the areas.

4. The network structure simplification processing method for power distribution network reconstruction according to claim 1, characterized in that: in the step 2, a topology reconstruction strategy is generated by using the adjacency relation between the regions, the topology reconstruction strategy is restored according to the corresponding relation between the regions and the nodes, and the restored network structure is simplified by using a power flow simplification model.

5. The network structure simplification processing method for power distribution network reconstruction according to claim 3, characterized in that: the step 2 specifically comprises the following steps:

step 2-1: reconstructing the simplified topological structure by adopting an artificial intelligence method according to the adjacency relation between the regions to generate a topological reconstruction strategy;

step 2-2: judging whether the generated topology reconstruction strategy is an island or a ring network according to the characteristics of the radial structure of the power distribution network and the power supply of the single power supply, if so, returning to the step 2-1, and regenerating the topology reconstruction strategy; otherwise, executing the step 2-3;

step 2-3: restoring the topological structure reconstructed through the topological reconstruction strategy by using the corresponding relation between the region and the node;

step 2-4: and simplifying the restored network structure by using the power flow simplification model.

6. The network structure simplification processing method for power distribution network reconstruction according to claim 5, characterized in that: in the step 2-3, the connection relation among all the regions is determined according to the generated topology reconstruction strategy, the corresponding nodes and branches are found through the region adjacency matrix C, and the Z is combined₁、Z₂、...、Z_l、...、Z_nzoneAnd the internal network structure can obtain the whole power distribution network structure, and the restoration of the topological structure reconstructed through the topological reconstruction strategy is completed.

7. The network structure simplification processing method for power distribution network reconstruction according to claim 5, characterized in that: in the simplified power flow model of step 2-4, for any feeder segment with multiple branches, when the power flow direction is from the head end node A of the feeder segment to the tail end node B, the phase voltage drop between the head end node A and the tail end node B is usedIt shows, as follows:

$\mathrm{\Δ}{\stackrel{\·}{U}}_{AB}=\underset{i=1}{\overset{N}{\Σ}}{L}_i(r+jx){\left(\frac{\underset{t=i}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t}{{\stackrel{\·}{U}}_A}\right)}^{*}---\left(6\right)$

wherein N is the number of nodes on the feeder section, L_iThe length of the ith branch is the length of the ith branch,the phase voltage at the head end node a on the feeder section,for the complex power of node t, the symbol denotes the conjugate;

assuming that the total length of the feeder line section is L, assuming that the feeder line section is a uniform conductor, r and x respectively represent resistance and reactance of the feeder line section in unit length, the voltage drop of the phase voltage from the head end node A to the equivalent node DAnd voltage drop of phase voltage from node D to node BRespectively expressed as:

$\mathrm{\Δ}{\stackrel{\·}{U}}_{AD}=L_{AD}(r+jx){\left(\frac{{\stackrel{\·}{S}}_D}{{\stackrel{\·}{U}}_A}\right)}^{*}---\left(7\right)$

$\mathrm{\Δ}{\stackrel{\·}{U}}_{DB}=0---\left(8\right)$

wherein,is the complex power of equivalent node D, L_ADThe length of a branch from a head-end node A to an equivalent node D;

the combined formulae (6) to (8) can be given as follows:

$\underset{i=1}{\overset{N}{\Σ}}{L}_i{\left(\frac{\underset{t=i}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t}{{\stackrel{\·}{U}}_A}\right)}^{*}={\left(\frac{{\stackrel{\·}{S}}_D}{{\stackrel{\·}{U}}_A}\right)}^{*}{L}_{AD}---\left(9\right)$

when the power flow direction is from the tail end node B to the head end node A on the feeder segment, the following steps are provided:

$\underset{i=1}{\overset{N}{\Σ}}{L}_{i+1}{\left(\frac{\underset{t=1}{\overset{i}{\Σ}}{\stackrel{\·}{S}}_t}{{\stackrel{\·}{U}}_B}\right)}^{*}={\left(\frac{{\stackrel{\·}{S}}_D}{{\stackrel{\·}{U}}_B}\right)}^{*}{L}_{DB}---\left(10\right)$

wherein,is the phase voltage, L, of the tail node B on the feeder section_DBIs the branch length, L, from the equivalent node D to the tail-end node B_i+1The length of the (i + 1) th branch;

due to L_AD+L_DBL, available as:

${\stackrel{\·}{S}}_D=\frac{1}{L}\[\underset{i=1}{\overset{N}{\Σ}}{L}_i\underset{t=i}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t+\underset{t=1}{\overset{N}{\Σ}}{L}_{i+1}\underset{t=1}{\overset{i}{\Σ}}{\stackrel{\·}{S}}_t\]=\underset{t=1}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t---\left(11\right)$

$L_{AD}=\frac{\underset{i=1}{\overset{N}{\Σ}}{L}_i\underset{t=i}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t}{\underset{t=1}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t}---\left(12\right)$

$L_{DB}=\frac{\underset{i=1}{\overset{N}{\Σ}}{L}_{i+1}\underset{t=1}{\overset{i}{\Σ}}{\stackrel{\·}{S}}_t}{\underset{t=1}{\overset{N}{\Σ}}{\stackrel{\·}{S}}_t}---\left(13\right).$

8. the network structure simplification processing method for power distribution network reconstruction according to claim 7, characterized in that: the step 3 specifically comprises the following steps:

step 3-1: carrying out forward-pushing and backward-replacing power flow simplified calculation on the restored and simplified network structure, and calculating a reconstruction index according to a power flow analysis result;

step 3-2: comparing and analyzing each topology reconstruction strategy according to the reconstruction index, judging whether the network structure corresponding to the topology reconstruction strategy is the optimal network structure meeting the reconstruction condition, if so, selecting the network structure as the optimal network structure, and simultaneously outputting the network structure and the reconstruction index; otherwise, returning to the step 2-1 to regenerate the topology reconstruction strategy.

9. The network structure simplification processing method for power distribution network reconstruction according to claim 8, characterized in that: the step 3-1 specifically comprises the following steps:

step 3-1-1: carrying out forward-pushing back to replace the power flow simplified calculation on the restored and simplified network structure to obtain the A-phase voltage of the head-end node of the feeder line section in the power flow simplified modelOf tail-end node BPhase voltageAnd the phase voltage of the equivalent node D

Step 3-1-2: will be provided withAndperforming load flow simplified calculation on the network structure as a known quantity, carrying out forward recursion from a tail end node of the network structure, judging whether a node to be solved belongs to a T contact, if not, executing a step 3-1-3, and if so, executing a step 3-1-4;

step 3-1-3: when the node to be solved does not belong to the T contact, calculating the branch loss of the tail end node kIt is expressed as:

${\stackrel{\·}{S}}_{L,k}=(r+jx)L_k|{\left(\frac{{\stackrel{\·}{S}}_{P,k}}{{\stackrel{\·}{U}}_k}\right)}^{*}{|}^2---\left(14\right)$

wherein L is_kIs the branch length of the tail-end node k,the phase voltage at the tail-end node k,for the total power flowing through the tail end node k, P represents the total power, and L represents the loss;

thus, the total power flowing through node k-1Expressed as:

${\stackrel{\·}{S}}_{P,k-1}={\stackrel{\·}{S}}_{L,k}+{\stackrel{\·}{S}}_{P,k}+{\stackrel{\·}{S}}_{k-1}---\left(15\right)$

wherein,is the complex power of node k-1;

phase voltage of node k-1Expressed as:

${\stackrel{\·}{U}}_{k-1}={\stackrel{\·}{U}}_k+(r+jx)L_k{\left(\frac{{\stackrel{\·}{S}}_{P,k}}{{\stackrel{\·}{U}}_k}\right)}^{*}---\left(16\right)$

step 3-1-4: when the node to be solved belongs to the T joint, because recursion is carried out according to the reverse direction of the tide direction, nodes and branches on adjacent feeder line sections at the downstream of the tail end node k are known, and the calculation of the flow passing through is carried outTotal power of tail-end node kComprises the following steps:

${\stackrel{\·}{S}}_{P,k}=\underset{v\∈\mathrm{\θ}}{\Σ}({\stackrel{\·}{S}}_{L,kv}+{\stackrel{\·}{S}}_{P,kv})+{\stackrel{\·}{S}}_k---\left(17\right)$

the theta is a set of all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction; v represents all adjacent feeder segments at the downstream of the tail end node k according to the power flow direction;the branch loss on the v-th downstream feeder line adjacent to the node k is shown, wherein L represents the loss, and kv is the v-th downstream feeder line segment adjacent to the tail end node k;the total power of tail end nodes of the downstream feeder line end adjacent to the node k passes through the nth line, and P represents the total power;is the complex power of node k;

step 3-1-5: the bus loss of the computing network structure is as follows:

${\stackrel{\·}{S}}_L=\underset{w\∈\mathrm{\λ}}{\Σ}{\stackrel{\·}{S}}_{L,w}---\left(18\right)$

wherein,in order to account for the bus loss of the network architecture,for the loss of a feeder segment w, λ is the set of all feeder segments, and w is the feeder segment belonging to the set λ.