CN116316486B

CN116316486B - Power distribution network line protection method, system and equipment

Info

Publication number: CN116316486B
Application number: CN202310519156.XA
Authority: CN
Inventors: 廖峰; 区伟潮; 吴海江; 陈锦荣; 刘秀甫; 黎永豪; 刘世丹; 汤志锐; 邱桂华; 罗永润
Original assignee: Foshan Power Supply Bureau of Guangdong Power Grid Corp
Current assignee: Foshan Power Supply Bureau of Guangdong Power Grid Corp
Priority date: 2023-05-10
Filing date: 2023-05-10
Publication date: 2023-09-08
Anticipated expiration: 2043-05-10
Also published as: CN116316486A

Abstract

The invention discloses a power distribution network line protection method, a system and equipment. According to the fault line selection method, fault judgment is carried out on the power distribution network line according to a preset fault line selection criterion, and a fault line is determined according to a judgment result; reducing the order of the static topology matrix of the protection domain according to the fault line node of the fault line to generate a protection application topology matrix; node information corresponding to the fault line nodes is extracted, a fault information matrix is constructed, and a fault positioning matrix is constructed by adopting the fault information matrix and the protection application topology matrix; and generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix, and executing tripping operation corresponding to the tripping command. The protection system solves the technical problems that the existing protection system has larger operation scale and is not suitable for the network topology structure. The invention can quickly find the fault position and issue a tripping command, and control the corresponding breaker to trip, thereby quickly and accurately isolating the fault.

Description

Power distribution network line protection method, system and equipment

Technical Field

The invention relates to the technical field of power distribution networks, in particular to a power distribution network line protection method, a system and equipment.

Background

The distributed power supplies (Distributed Generation, DG) are connected into the power distribution network in a large quantity, so that the traditional single-power radial network is changed into a complex network with multiple power supplies, the network structure, the operation mode and the short-circuit current characteristics of the complex network are changed, the fault current of the power distribution network can be subjected to external drawing or boosting, and the selectivity and the sensitivity of the conventional staged line protection are influenced. Meanwhile, due to uncertainty of DG types, control strategies and grid-connected capacity and intermittent operation characteristics thereof, response characteristics of the DG types, the control strategies and the grid-connected capacity to faults of the power distribution network are different, and difficulty is increased for protection setting and protection matching is more difficult. Along with the continuous improvement of DG permeability, the low voltage ride through capability of DG must be ensured in order to ensure the running reliability of the system, which requires protection to act rapidly before DG exits from running, and provides a new challenge for protecting the mobility.

Therefore, there are two major classes of protection based on local information and protection based on communication for active distribution network protection at present. The protection based on the local information is mainly realized by adding the direction element, the intelligent electronic equipment and the self-adaptive modification fixed value on the basis of current protection, and is easy to realize, but the operation mode of the distribution network after DG is connected is changeable, and the protection delay and the setting coordination between the sections still have difficulty. Compared with the limitation of local information protection, the protection based on communication has wider application prospect in an active power distribution network. The pilot protection based on adjacent information is applied to the power distribution network, so that part of problems of power distribution network protection can be solved, but the pilot protection is limited by the problems of a plurality of branches of the power distribution network, flexible and changeable operation modes, DG control strategies, data synchronization and the like, and the reliability and the applicability are still to be further improved. In addition, various protection principles based on wide area, regional or local information are adopted, such as a wide area protection system is constructed, and multi-point and multi-type information is incorporated into the protection system to rapidly perform fault location; performing associated domain searching of the intelligent electronic device, and implementing fault isolation in the associated domain by adopting a current differential protection principle; dividing a protection area directly according to the configuration condition of the circuit breaker, and combining local protection information to realize area protection; firstly, defining different types of nodes, completing primary fault positioning between a bus node and three or more branches by using positive sequence components of fault current, and then completing secondary accurate positioning by using current abrupt change values in a locking area; and acquiring measurement and control and topology information of the local association area through the peer-to-peer communication network to carry out autonomous decision. The protection has the defects of larger operation scale and inadaptability to the change of the network topology structure, and the protection problem of the active power distribution network is still to be solved.

Disclosure of Invention

The invention provides a power distribution network line protection method, a system and equipment, which solve the technical problems that the existing protection system has larger operation scale and is not suitable for a network topology structure, and the active power distribution network protection problem is still to be solved.

The power distribution network line protection method provided by the first aspect of the invention comprises the following steps:

responding to a received power distribution network line protection request, and acquiring a topology structure of a power distribution network line corresponding to the power distribution network line protection request;

constructing a protection domain static topology matrix by adopting each line node corresponding to the topology structure and a connection relation corresponding to each line node;

performing fault judgment on the power distribution network line according to a preset fault line selection criterion, and determining a fault line according to a judgment result;

reducing the static topology matrix of the protection domain according to the fault line node of the fault line to generate a protection application topology matrix;

node information corresponding to the fault line nodes is extracted, a fault information matrix is constructed, and a fault positioning matrix is constructed by adopting the fault information matrix and the protection application topology matrix;

and generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix, and executing tripping operation corresponding to the tripping command.

Optionally, the step of obtaining the topology structure of the power distribution network corresponding to the power distribution network protection request in response to the received power distribution network protection request includes:

responding to a received power distribution network line protection request, and extracting a corresponding power distribution network line in a database according to the power distribution network line protection request;

determining equipment corresponding to the power distribution network line as a line node;

and connecting the circuit nodes according to the connection relation of the power distribution network circuit by adopting a preset path sequential searching method to construct a topological structure.

Optionally, the step of constructing a protection domain static topology matrix by adopting each line node corresponding to the topology structure and a connection relationship corresponding to each line node includes:

sequencing each line node of the topological structure according to a line switch where each line interval is positioned, and generating a plurality of line node numbers;

determining the order of a topological matrix according to the number of the line nodes corresponding to the topological structure;

setting the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line nodes as an mth row matrix element corresponding to the topological matrix; wherein m is a positive integer;

When a preset line node number is connected with the line node corresponding to the mth line node number respectively, and the preset line node number is larger than or equal to the mth line node number, setting a matrix element corresponding to the preset line node number in an mth row matrix as a first threshold element;

when the preset line node numbers are connected with the line nodes corresponding to the mth line node numbers respectively, and the preset line node numbers are smaller than the mth line node numbers or the line nodes corresponding to the preset line node numbers and the mth line node numbers are not connected, setting matrix elements corresponding to the preset line node numbers in the mth line matrix as second threshold elements;

setting one line node in the rest line nodes of the topological structure as a new mth line node, and performing jump execution, wherein the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line node is set as an mth row matrix element corresponding to a topological matrix; wherein m is a positive integer;

and constructing a protection domain static topology matrix by adopting a plurality of first threshold elements and a plurality of second threshold elements.

Optionally, the step of performing fault judgment on the power distribution network line according to a preset fault line selection criterion and determining a fault line according to a judgment result includes:

judging whether the power distribution network line is a fault line according to a preset fault line selection criterion;

if the current value of the line outlet corresponding to the power distribution network line is larger than a setting value and the current flow direction of the line outlet is in a preset positive direction, determining the line corresponding to the power distribution network line as a fault line;

and if the current value of the line outlet is larger than the setting value and the current flow direction of the line outlet is a preset negative direction or the current value of the line outlet is smaller than the setting value, determining the line corresponding to the power distribution network line as a non-fault line.

Optionally, the step of reducing the protection domain static topology matrix according to the fault line node of the fault line to generate a protection application topology matrix includes:

extracting a fault line node corresponding to the fault line and a downstream line node corresponding to a downstream area of the fault line node;

and reserving matrix rows and columns corresponding to the fault line nodes and the downstream line nodes in the protection domain static topology matrix, and removing residual matrix rows and columns in the protection domain static topology matrix to generate a protection application topology matrix.

Optionally, the step of extracting node information corresponding to the fault line node, constructing a fault information matrix, and constructing a fault positioning matrix by adopting the fault information matrix and the protection application topology matrix includes:

extracting node numbers and line node fault information corresponding to the fault line nodes to generate a fault information matrix;

and calculating a matrix multiplication value between the fault information matrix and the protection application topology matrix to generate a fault positioning matrix.

Optionally, the step of generating a corresponding trip command according to the fault location corresponding to the fault location matrix and executing the trip operation corresponding to the trip command includes:

judging whether only one first threshold element exists in the fault locating matrix;

if yes, determining that a downstream area of the line node corresponding to the first threshold element fails, and determining the downstream area of the line node corresponding to the first threshold element as a failure position;

if not, determining that the downstream area of the line node corresponding to the last first threshold element fails, and determining the downstream area of the line node corresponding to the last first threshold element as a failure position;

Determining a breaker corresponding to the fault position according to the fault position, and generating a tripping command;

and executing tripping operation on the circuit breaker according to the tripping command.

Optionally, the method further comprises:

when detecting that a tie switch in the power distribution network line is in an off state, extracting a switch line node corresponding to the tie switch and a switch downstream line node corresponding to a downstream area of the switch line node;

and removing corresponding matrix rows and columns of the switch line nodes and the switch downstream line nodes in the protection domain static topology matrix to generate a protection domain real-time topology matrix.

A second aspect of the present invention provides a power distribution network line protection system, including:

the topology structure module is used for responding to the received power distribution network line protection request and acquiring the topology structure of the power distribution network line corresponding to the power distribution network line protection request;

the protection domain static topology matrix module is used for constructing a protection domain static topology matrix by adopting each line node corresponding to the topology structure and the corresponding connection relation of each line node;

the fault line module is used for carrying out fault judgment on the power distribution network line according to a preset fault line selection criterion, and determining a fault line according to a judgment result;

The protection application topology matrix module is used for reducing the static topology matrix of the protection domain according to the fault line nodes of the fault line to generate a protection application topology matrix;

the fault positioning matrix module is used for extracting node information corresponding to the fault line nodes, constructing a fault information matrix, and constructing a fault positioning matrix by adopting the fault information matrix and the protection application topology matrix;

and the tripping operation module is used for generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix and executing tripping operation corresponding to the tripping command.

An electronic device according to a third aspect of the present invention includes a memory and a processor, where the memory stores a computer program, where the computer program when executed by the processor causes the processor to perform the steps of the power distribution network line protection method according to any one of the above.

From the above technical scheme, the invention has the following advantages:

according to the method, the topology structure of the power distribution network line corresponding to the power distribution network line protection request is obtained by responding to the received power distribution network line protection request; constructing a protection domain static topology matrix by adopting each line node corresponding to a topology structure and a connection relation corresponding to each line node; performing fault judgment on the power distribution network line according to a preset fault line selection criterion, and determining a fault line according to a judgment result; reducing the order of the static topology matrix of the protection domain according to the fault line node of the fault line to generate a protection application topology matrix; node information corresponding to the fault line nodes is extracted, a fault information matrix is constructed, and a fault positioning matrix is constructed by adopting the fault information matrix and the protection application topology matrix; and generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix, and executing tripping operation corresponding to the tripping command. The protection system solves the technical problems that the existing protection system has larger operation scale and is not suitable for a network topology structure, and the protection problem of an active power distribution network is still to be solved.

The static topology is connected between the upper and lower stages of the switch devices in the protection domain, so that the matrix is sparse, and the dynamic update of the network topology is easy; the fault range is greatly reduced by intensively comparing the fault characteristics of all outgoing lines, the network topology matrix is reduced to form a protection application topology, and the analysis and calculation are fast and reliable; the centralized decision is protected, the upper and lower level coordination is not needed, and the protection mobility and the selectivity are both considered; the fault tolerance is improved by utilizing information redundancy, so that the reliability requirement is met; the fault effective information extraction considers the influence of DG, so that protection is still effective when the system operation mode, DG type, control strategy, DG access capacity and access position are changed; and the developed protection complete device is used for carrying out an experiment based on an RTplus platform, and the experiment result shows that the protection outlet time is less than 60ms when different types of faults occur in the outgoing line and the off-line of the transformer substation, and the target terminal can receive the tripping command issued by the protection device, control the corresponding circuit breaker to trip and rapidly and accurately isolate the faults.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.

Fig. 1 is a flowchart of steps of a power distribution network line protection method according to a first embodiment of the present invention;

fig. 2 is a flowchart of steps of a power distribution network line protection method according to a second embodiment of the present invention;

fig. 3 is a schematic structural diagram of a distribution network with DG multipoint access according to a second embodiment of the present invention;

fig. 4 is a static topology diagram of a protection domain according to a second embodiment of the present invention;

fig. 5 is a judgment flow chart of a centralized rapid interphase short-circuit protection fault judgment according to a second embodiment of the present invention;

fig. 6 is a block diagram of a circuit protection system for a power distribution network according to a fourth embodiment of the present invention.

Detailed Description

The embodiment of the invention provides a power distribution network line protection method, a system and equipment, which are used for solving the technical problems that the existing protection system has larger operation scale and is not suitable for a network topology structure, and the active power distribution network protection problem is still to be solved.

In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1, fig. 1 is a flowchart illustrating steps of a power distribution network line protection method according to an embodiment of the present invention.

The invention provides a power distribution network line protection method, which comprises the following steps:

step 101, responding to a received power distribution network line protection request, and acquiring a topology structure of a power distribution network line corresponding to the power distribution network line protection request.

It should be noted that a power distribution network line protection request refers to a request for protecting a line of a certain power distribution network.

Topology refers to the network structure formed between the line node devices.

In the embodiment of the invention, when the power distribution network line protection request is received, the power distribution network line corresponding to the power distribution network line protection request is acquired, so that the topology structure corresponding to the power distribution network line is acquired.

And 102, constructing a protection domain static topology matrix by adopting each line node corresponding to the topology structure and the connection relation corresponding to each line node.

It should be noted that, the adjacency matrix describes the connection relationship between the line nodes, does not pay attention to the branch condition between the nodes, and is suitable for centralized line protection. Each line switch (switch) and equipment in the power distribution network line are represented by line nodes, a line outgoing switch is used as an initial line node, line nodes connected with the initial line node and positioned at the downstream of the initial line node are sequentially searched, and a unidirectional adjacency matrix is used for describing feeder topology. All line nodes of a plurality of line intervals in the protection domain are obtained, each line node is numbered in sequence according to each line interval, and a main line switch or a branch switch where each line interval is located is sequentially numbered to obtain a plurality of line node numbers.

The protection domain static topology matrix refers to adopting a line node number corresponding to each line node in the protection domain as a corresponding matrix row, that is, each matrix element in each matrix row represents the connection relationship between the line node corresponding to the line node number and the line node in the downstream area.

In the embodiment of the invention, a matrix with a corresponding order is set according to the number of the line nodes, all the matrix orders are used for constructing a protection domain static topology matrix, and specifically, matrix rows of each protection domain static topology matrix represent line nodes corresponding to one line node number and connection relations between the line nodes and other line nodes.

And 103, performing fault judgment on the power distribution network line according to a preset fault line selection criterion, and determining a fault line according to a judgment result.

It should be noted that the preset fault line selection criterion refers to determining whether a fault exists in a power distribution network according to a current characteristic at a line outlet of the line.

In the embodiment of the invention, the current value and the current direction of the current at the line outlet of the power distribution network line are obtained, and whether a fault line exists can be determined through the current value and the current direction.

And 104, reducing the static topology matrix of the protection domain according to the fault line node of the fault line to generate a protection application topology matrix.

In the embodiment of the invention, when a fault line exists, the line node number corresponding to the fault line and the line node number of the downstream area are obtained, the matrix row represented by the line node number and the line node number of the downstream area on the protection domain static topology matrix is removed, and the remaining new topology matrix is the protection application topology matrix.

And 105, extracting node information corresponding to the fault line nodes, constructing a fault information matrix, and constructing a fault positioning matrix by adopting the fault information matrix and the protection application topology matrix.

Note that the node information refers to line node failure information.

The fault information matrix refers to matrix rows and matrix columns of a topology matrix generated according to node information corresponding to each fault line node.

In the embodiment of the invention, the line node fault information corresponding to each fault line node is obtained, a fault information matrix is constructed according to the serial number sequence of the fault line node, and a fault positioning matrix is obtained by calculating the matrix multiplication value of the fault information matrix and the protection application topology matrix.

And 106, generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix, and executing tripping operation corresponding to the tripping command.

The trip command refers to a command to trip a certain breaker.

In the embodiment of the invention, the fault position is acquired through the fault positioning matrix, the circuit breaker of the fault position can be determined after the fault position is acquired, a tripping command is issued to the circuit breaker, and tripping operation is executed to the circuit breaker.

Referring to fig. 2-5, fig. 2 is a flowchart illustrating steps of a power distribution network line protection method according to a third embodiment of the present invention.

Step 201, responding to a received power distribution network line protection request, and extracting a corresponding power distribution network line in a database according to the power distribution network line protection request.

It should be noted that the distribution network line refers to a DG multipoint high penetration access distribution network line.

In the embodiment of the invention, when the power distribution network line protection request is received, the corresponding power distribution network line is extracted from a database (SCD file) according to the line data of the power distribution network line protection request.

And 202, determining equipment corresponding to the power distribution network line as a line node.

In the embodiment of the invention, the topological relation in the SCD file described by the hierarchical structure is expressed through the connection points, and the line switch and the equipment corresponding to the power distribution network line are set as the line nodes.

It should be noted that, as shown in fig. 3, three lines of the transformer substation corresponding to the power distribution network are outgoing lines L1, L2 and L3, and the circuit breakers are CB1, CB2 and CB3 respectively, wherein K23 is a tie switch, K25 is an end switch, and K11, K12, K21, K22, K24, K26, K27, K28 and K31 are line nodes corresponding to each device or switch.

And 203, connecting all the circuit nodes according to the connection relation of the power distribution network circuit by adopting a preset path sequential searching method, and constructing a topological structure.

The preset path sequential searching method refers to searching paths from a starting line node to an end-most line node of a power distribution network line sequentially for each line node and connection relations between the line node and other line nodes.

In the embodiment of the invention, the circuit nodes corresponding to the equipment are connected according to the connection relation of the power distribution network circuit by utilizing a path sequential search method, and the tree structure data of the connection relation of the equipment is constructed, so that the topological structure can be obtained.

Specifically, for centralized line protection, the fault location determination only needs to be of a circuit breaker topology structure, so that a branch is omitted in a static topology diagram of a protection domain, as shown in a topology structure diagram in fig. 4.

In particular, the feeder terminal FTU configuration is shown in fig. 3, with full coverage of the communication network. The protection domain of the centralized rapid line protection of the transformer substation 1 side is three lines. Therefore, for the radial lines L1 and L3, the breaker connection condition in the entire line needs to be identified; for the dual supply series line L2, the connection of all the circuit breakers CB2 to K25 needs to be identified.

And 204, constructing a protection domain static topology matrix by adopting each line node corresponding to the topology structure and the connection relation corresponding to each line node.

Optionally, step 204 includes the following steps S11-S17:

s11, sequencing each line node of the topological structure according to a line switch where each line interval is located, and generating a plurality of line node numbers;

s12, determining the order of a topological matrix according to the number of line nodes corresponding to the topological structure;

s13, setting the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line nodes as an mth row matrix element corresponding to the topological matrix; wherein m is a positive integer;

s14, when the preset line node numbers are connected with the line nodes corresponding to the mth line node numbers respectively, and the preset line node numbers are larger than or equal to the mth line node numbers, setting matrix elements corresponding to the preset line node numbers in the mth row matrix as first threshold elements;

s15, when the preset line node numbers are connected with the line nodes corresponding to the mth line node numbers respectively, and the preset line node numbers are smaller than the mth line node numbers or the preset line node numbers are not connected with the line nodes corresponding to the mth line node numbers respectively, setting matrix elements corresponding to the preset line node numbers in the mth line matrix as second threshold elements;

S16, setting one line node in the rest line nodes of the topological structure as a new mth line node, and performing jump execution to set the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line node as an mth row matrix element corresponding to the topological matrix; wherein m is a positive integer;

s17, constructing a protection domain static topology matrix by adopting a plurality of first threshold elements and a plurality of second threshold elements.

The preset line node number refers to the number of the line node corresponding to the mth line node number, which is the same line or diagonal line.

The first threshold element refers to 1 and the second threshold element refers to 0.

In the embodiment of the invention, the protection domain has M line nodes at intervals, and the m×m order matrix M can be used for representing the topology structure. The m-th row element represents the connection condition of the m-th line node and the rest line nodes, and specifies that matrix elements corresponding to each line node connected with the m-th line node and located in the downstream area of the line node are denoted by '1', the matrix elements of the diagonal line are denoted by '1', and other matrix elements are respectively denoted by '0'. Matrix elements in the protection domain static topology matrix M The definition is as follows:

；

wherein, the liquid crystal display device comprises a liquid crystal display device,and->Any two line nodes.

Specifically, referring to fig. 4, matrix elements in the protection domain static topology matrix M are combinedThe generation of the protection domain static topology matrix M is:

。

and 205, performing fault judgment on the power distribution network line according to a preset fault line selection criterion, and determining a fault line according to a judgment result.

Optionally, step 205 includes the following steps S21-S23:

s21, judging whether the power distribution network line is a fault line according to a preset fault line selection criterion;

s22, if the current value of the line outlet corresponding to the power distribution network line is larger than a setting value and the current flow direction of the line outlet is in a preset positive direction, determining the line corresponding to the power distribution network line as a fault line;

s23, if the current value of the line outlet is larger than a setting value, and the current direction of the line outlet is a preset negative direction or the current value of the line outlet is smaller than the setting value, determining the line corresponding to the power distribution network line as a non-fault line.

The setting value refers to a current set value of the line.

In the embodiment of the invention, the positive current direction in the DG branch is set as DG flow to the grid-connected point, the positive current direction in the load branch is set as flow to the load, and the positive current direction in other branches is set as the bus pointing line. Forming fault line selection criteria according to current characteristics at outlets of fault lines and non-fault lines: (1) The current value of the line outlet corresponding to the power distribution network line is larger than a setting value, the current direction is the current positive direction, and the fault line is judged; (2) And judging that the line outlet current value corresponding to the power distribution network line is larger than a setting value, the current flow direction is the current reverse direction or the current is smaller than the setting value, and judging that the line is a non-fault line. Considering the external drawing action of the current outlet short circuit of the current line DG when the current line DG fails, the current of the current outlet short circuit may be reduced, but the reduction value of the current outlet short circuit may not exceed 2 times of the rated current of the current line, so that the current setting value of the fault line selection is greater than the maximum load current of the current line.

In particular, for DG branch, fault information at switchThe definition is as follows:

；

in the method, in the process of the invention,indicating the flow through DG grid-connected switch->Current value of>The grid-connected DG rated current value is shown.

For other branches, fault information at the switchThe definition is as follows:

；

in the method, in the process of the invention,indicating switch->The value of the current flowing through the valve->The over-current setting value of the line is shown and is larger than the cold starting current of the line.

And 206, reducing the static topology matrix of the protection domain according to the fault line nodes of the fault line to generate a protection application topology matrix.

Optionally, step 206 includes the following steps S31-S32:

s31, extracting a fault line node corresponding to a fault line and a downstream line node corresponding to a downstream area of the fault line node;

s32, reserving matrix rows and columns corresponding to the fault line nodes and the downstream line nodes in the protection domain static topology matrix, and removing the residual matrix rows and columns in the protection domain static topology matrix to generate a protection application topology matrix.

When the small-current grounding system is in interphase short circuit or the small-resistance grounding system is in interphase or grounding short circuit, the current value of the fault line is obviously larger than that of the non-fault line and the directions are opposite, and the fault line can be primarily judged by detecting and comparing the outlet line phase current or the zero sequence current corresponding to each power distribution network in the protection domain. Thus, the topology information for further determining the location of the fault, i.e. the protection application topology, can be greatly narrowed down to include only the faulty line.

Therefore, the real-time topology matrix of the protection domain is further reduced according to the fault line selection result, and the protection application topology matrix T is formed. The protection domain static topology matrix is unchanged whether the switch is downstream of the load or the distributed power supply.

In the embodiment of the present invention, assuming that the downstream area corresponding to the K27 line node of the line L2 shown in fig. 3 fails, the protection application topology structure only includes 5 line nodes of the switches CB2, K21, K22, K26 and K27, and the protection domain real-time topology matrix P is further reduced to form the protection application topology matrix T, where the expression form of the protection application topology matrix T is as follows:

。

step 207, node information corresponding to the fault line nodes is extracted, a fault information matrix is constructed, and a fault positioning matrix is constructed by adopting the fault information matrix and the protection application topology matrix.

Optionally, step 207 includes the following steps S41-S42:

s41, extracting node numbers corresponding to the fault line nodes and line node fault information to generate a fault information matrix;

s42, calculating a matrix multiplication value between the fault information matrix and the protection application topology matrix to generate a fault positioning matrix.

The failure information matrix refers to a matrix of 1 row and m columns formed according to node information corresponding to each failure line node.

In the embodiment of the present invention, it is assumed in the foregoing that the downstream area corresponding to the K27 line node of the line L2 shown in fig. 3 is faulty, the node information corresponding to the faulty line node is extracted, and a fault information matrix F is generated, where the expression form of the fault information matrix F is as follows:

。

multiplying the fault information matrix F with the protection application topology matrix T to obtain a fault positioning matrix D of 1 row and m columns, wherein the expression form of the fault positioning matrix D is as follows:

。

step 208, generating a corresponding tripping command according to the fault position corresponding to the fault positioning matrix, and executing tripping operation corresponding to the tripping command.

Optionally, step 208 includes the following steps S51-S55:

s51, judging whether the fault locating matrix has only one first threshold value element or not;

s52, if so, determining that a downstream area of the line node corresponding to the first threshold element fails, and determining the downstream area of the line node corresponding to the first threshold element as a failure position;

s53, if not, determining that the downstream area of the line node corresponding to the last first threshold element fails, and determining the downstream area of the line node corresponding to the last first threshold element as a failure position;

s54, determining a breaker corresponding to the fault position according to the fault position, and generating a tripping command;

S55, executing tripping operation on the circuit breaker according to the tripping command.

It should be noted that, according to the expression form of the protection domain static topology matrix and the fault information matrix D, when a fault occurs between the line node and the connected line node corresponding to the downstream area, the matrix element corresponding to the line node in the fault location matrix is set to be 1; when a fault occurs in a downstream area of a connected line node corresponding to the downstream area of the fault node, determining a matrix element corresponding to the line node in the matrix as 2; when the fault loop does not pass through the line node, its corresponding matrix element is 0. Therefore, the downstream area of the node corresponding to element 1 in the fault location matrix D is the fault location.

In summary, the concentrated fast interphase short-circuit protection fault judging flow is shown in fig. 5.

Aiming at the grounding faults of the small-resistance grounding distribution network, when the grounding resistance is small, the zero-sequence current mutation characteristic is obvious, and the zero-sequence overcurrent fault detection function is put into. Grid-tie DG usually uses a neutral point ungrounded way, so protection does not need to take its effect into account.

Zero sequence overcurrent detection is set according to the capacitance current 50A (which can be achieved in extreme cases) of the non-fault section, when the zero sequence current of the measuring point is greater than 50A, fault information is 1, otherwise, the fault information is 0. And determining a protection application topology matrix T according to the fact that the zero sequence current of the fault line outlet is larger than a setting value, further forming a fault information matrix D according to the fact that the fault information of each measuring point at the upstream of the fault point is 1 and the downstream information is 0, and generating a fault positioning matrix by combining the protection application topology matrix T, wherein the downstream area of a line node corresponding to a matrix element 1 in the matrix is the fault position. For example, fault location matrix Wherein matrix element 1 in the fault location matrix D corresponds to the downstream, i.e. fault location, of the line node K27.

In practical application, the embodiment of the invention aims to solve the problem of reliability when information is missing or information is wrong based on the protection of communication, and improves the fault tolerance of line protection. An inter-phase short occurs downstream of K27 in figure 3,if the FTU22 does not send out a fault message or the content of the fault message is wrong for some reason, the protection identifies all fault information according to the protection application topology, so that the fault tolerance of the algorithm can be improved. At this time, the fault information matrix is。/>

Protecting the application topology matrix T from being changed to obtain a fault positioning matrix. At this time, the fault locating matrix D has a plurality of 1 matrix elements, and it is determined that the downstream of the line node corresponding to the last 1 matrix element has a fault.

And determining a breaker corresponding to the fault position according to the fault position, generating a tripping command, and controlling the corresponding breaker to trip by the target terminal after receiving the tripping command issued by the protection device.

Optionally, the method further comprises the following steps S61-S62:

s61, when detecting that a tie switch in a power distribution network line is in an off state, extracting a switch line node corresponding to the tie switch and a switch downstream line node corresponding to a downstream area of the switch line node;

S62, removing corresponding matrix rows and columns of the switch line nodes and the switch downstream line nodes in the protection domain static topology matrix, and generating a protection domain real-time topology matrix.

In the embodiment of the present invention, as shown in fig. 3, when detecting that the tie switch K23 in the distribution network is in an off state, the downstream areas K24, K25 and K28 thereof will not be in the centralized protection range of the substation 1 side, and the protection domain static topology matrix is reduced, that is, the matrix rows corresponding to K23, K24, K25 and K28 are removed, so as to form the protection domain real-time topology matrix P, where the expression of the protection domain real-time topology matrix P is as follows:

。

The third embodiment of the invention provides a test based on an RTplus platform.

To test the centralized rapid line protection function, an RTplus platform-based test is built according to the distribution line structure diagram shown in fig. 3. The system voltage class is 10kV, and a neutral point is grounded through a small resistor, so that the cable line is adopted. A station domain type protection device and 1 intelligent switch are installed in a transformer substation 1, a feeder terminal device and the intelligent switch are installed at each switch outside the transformer substation, and a communication network is formed by optical fiber networking. The lengths of three outgoing lines L1, L2 and L3 of the transformer substation are 3km and 4km respectively, and the distance between a first switch outside the transformer substation and an outgoing line switch is 1km; in L2, the distance between two switches on the main line is 2km, and the branch points of the branch lines are all positioned in the middle of the sections. The loads are all 0.9MW+0.3Mvar, DG1 is a synchronous generator, the capacity is 0.5MW, DG2 is an inversion type distributed power supply, and the capacity is 0.25MW.

The test indexes comprise protection outlet time and switch tripping condition when different types of faults occur at different positions such as a main line, a load branch, a DG branch, a line outlet and the like. In the test, fault positions F1-F6 are respectively arranged in a line L2 trunk line, namely 2.5km from a bus bar, a line L3 middle from a bus bar, a line L1 middle from a bus bar, a line L2 first branch from a branch point by 0.5km (namely downstream of K26), a line L2 second branch (namely downstream of K27) and a line L2 third branch (namely downstream of K28). The fault types are three-phase short circuit, any two-phase interphase short circuit and any two-phase grounding short circuit, which are all metallic short circuits, and each arrangement situation is tested once. For any phase single-phase earth fault, the initial phase angle of the fault is 15 degrees and 75 degrees, the transition resistance is 10 omega and 100 omega, and the combined scene of different fault conditions is tested. The fault time interval is set to 1s, the over-current setting value is set to 0.3kA, and the zero sequence current setting value is set to 50A.

Table 1 shows the protection exit time and the switch trip condition at the time of interphase short circuit in different scenarios.

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When an interphase fault occurs at F1, DG2 is located downstream of the fault point and DG1 is incorporated into the non-faulty line, and therefore, a short-circuit current will flow both upstream and downstream of the fault point and in the non-faulty line. However, as can be seen from table 1, the protection is not affected, and can still operate correctly, the protection exit time is less than 60ms, and the breaker K21 nearest to the fault point trips; when an interphase short circuit occurs at the F2 position in the DG-free grid-connected line L3, although the outlets of the other two lines are respectively provided with short circuit currents by DG1 and DG2, the protection can still quickly and selectively cut off faults; when faults near the outlet of the DG grid-connected line L1 occur, the final outlet breaker CB1 reliably trips; when the fault is caused at the DG branch F4, the DG grid-connected switch K26 is tripped rapidly; when the load branch F5 fails, the existence of DG2 may have external drawing or boosting effect on the short-circuit current flowing in each switch at the upstream, but ultimately has no influence on protection; when the tie switch K23 in the line L2 is in the off state, the downstream branch of K28 is not in the protection range, so that the protection does not judge the fault and does not issue a trip command.

Table 2 shows the protection exit time and the switch trip condition at the time of the ground short under different scenarios.

As can be seen from table 2, when the ground fault occurs at different positions, the protection is not affected by DG grid connection, and is also not affected by capacitive current to ground of the non-faulty line or the non-faulty section. And when the main line and the branch line in the protection domain are in fault, the protection outlet time is less than 60ms, and the target terminal receives a tripping command issued by the protection device and controls the corresponding circuit breaker to trip. Both the rapidity and selectivity requirements of the protection are met.

Referring to fig. 6, fig. 6 is a block diagram illustrating a circuit protection system for a power distribution network according to a fourth embodiment of the present invention.

The invention provides a power distribution network line protection system, which comprises:

the topology structure module 601 is configured to respond to a received power distribution network line protection request, and obtain a topology structure of a power distribution network line corresponding to the power distribution network line protection request;

the protection domain static topology matrix module 602 is configured to construct a protection domain static topology matrix by adopting connection relationships corresponding to each line node and each line node of the topology structure;

the fault line module 603 is configured to perform fault judgment on the power distribution network line according to a preset fault line selection criterion, and determine a fault line according to a judgment result;

The protection application topology matrix module 604 is configured to reduce the protection domain static topology matrix according to the fault line node of the fault line, and generate a protection application topology matrix;

the fault location matrix module 605 is configured to extract node information corresponding to the fault line nodes, construct a fault information matrix, and construct a fault location matrix by using the fault information matrix and the protection application topology matrix;

the trip operation module 606 is configured to generate a corresponding trip command according to the fault location corresponding to the fault location matrix, and perform a trip operation corresponding to the trip command.

Optionally, the topology module 601 includes:

the power distribution network line sub-module is used for responding to the received power distribution network line protection request and extracting the corresponding power distribution network line in the database according to the power distribution network line protection request;

the line node submodule is used for determining equipment corresponding to the power distribution network line as a line node;

and the topological structure sub-module is used for connecting all the circuit nodes according to the connection relation of the power distribution network circuit by adopting a preset path sequential searching method to construct a topological structure.

Optionally, the protection domain static topology matrix module 602 includes:

the circuit node coding sub-module is used for sequencing each circuit node of the topological structure according to the circuit switch where each circuit interval is located, and generating a plurality of circuit node numbers;

The topology matrix order submodule is used for determining the order of the topology matrix according to the number of the circuit nodes corresponding to the topology structure;

an m-th row matrix element sub-module, configured to set a connection relationship between a line node corresponding to an m-th line node number corresponding to a topology structure and a remaining line node as an m-th row matrix element corresponding to the topology matrix; wherein m is a positive integer;

the first threshold element submodule is used for setting matrix elements corresponding to the preset line node numbers in an m-th row matrix as first threshold elements when the preset line node numbers are connected with line nodes corresponding to the m-th line node numbers respectively and the preset line node numbers are larger than or equal to the m-th line node numbers;

a second threshold element sub-module, configured to set, as a second threshold element, a matrix element corresponding to the m-th row matrix for a preset line node number when the preset line node number is connected with the line node corresponding to the m-th line node number, and the preset line node number is smaller than the m-th line node number or the preset line node number is not connected with the line node corresponding to the m-th line node number;

the jump rotor module is used for setting one line node in the remaining line nodes of the topological structure as a new mth line node, and executing the jump to set the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the remaining line node as an mth line matrix element corresponding to the topological matrix; wherein m is a positive integer;

The protection domain static topology matrix submodule is used for constructing a protection domain static topology matrix by adopting a plurality of first threshold elements and a plurality of second threshold elements.

Optionally, the faulty wire module 603 includes:

the fault line judging sub-module is used for judging whether the power distribution network line is a fault line according to a preset fault line selecting criterion;

the fault line sub-module is used for determining a line corresponding to the power distribution network line as a fault line if the current value of the line outlet corresponding to the power distribution network line is larger than a setting value and the current direction of the line outlet is in a preset positive direction;

and the non-fault line sub-module is used for determining the line corresponding to the power distribution network line as a non-fault line if the line outlet current value is larger than a setting value and the line outlet current direction is a preset negative direction or the line outlet current value is smaller than the setting value.

Optionally, the protection application topology matrix module 604 includes:

a downstream line node submodule, configured to extract a fault line node corresponding to the fault line and a downstream line node corresponding to a downstream area of the fault line node;

the protection application topology matrix sub-module is used for reserving matrix rows and columns corresponding to the fault line nodes and the downstream line nodes in the protection domain static topology matrix, removing the residual matrix rows and columns in the protection domain static topology matrix and generating the protection application topology matrix.

Optionally, the fault location matrix module 605 includes:

the fault information matrix submodule is used for extracting node numbers corresponding to the fault line nodes and line node fault information and generating a fault information matrix;

the fault positioning matrix sub-module is used for calculating a matrix multiplication value between the fault information matrix and the protection application topology matrix to generate a fault positioning matrix.

Optionally, the trip operation module 606 includes:

the first threshold value element judging sub-module is used for judging whether only one first threshold value element exists in the fault locating matrix;

the first fault location sub-module is used for determining that a downstream area of the line node corresponding to the first threshold element is faulty if yes, and determining the downstream area of the line node corresponding to the first threshold element as a fault location;

the second fault location sub-module is used for determining that the downstream area of the line node corresponding to the last first threshold element fails if not, and determining the downstream area of the line node corresponding to the last first threshold element as a fault location;

the tripping command submodule is used for determining a breaker corresponding to the fault position according to the fault position and generating a tripping command;

And the tripping operation sub-module is used for executing tripping operation on the circuit breaker according to the tripping command.

Optionally, the system further comprises:

the switch downstream line node submodule is used for extracting a switch line node corresponding to the interconnection switch and a switch downstream line node corresponding to a downstream area of the switch line node when the interconnection switch in the power distribution network line is detected to be in an off state;

and the protection domain real-time topology matrix sub-module is used for removing corresponding matrix rows and columns of the switch circuit nodes and the switch downstream circuit nodes in the protection domain static topology matrix to generate the protection domain real-time topology matrix.

The fifth embodiment of the application also provides an electronic device, which comprises a memory and a processor, wherein the memory stores a computer program; the computer program, when executed by a processor, causes the processor to perform the steps of the power distribution network line protection method of any of the embodiments described above.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for protecting a power distribution network line, comprising:

constructing a protection domain static topology matrix by adopting a plurality of first threshold elements and a plurality of second threshold elements;

reserving matrix rows and columns corresponding to the fault line nodes and the downstream line nodes in the protection domain static topology matrix, and removing residual matrix rows and columns in the protection domain static topology matrix to generate a protection application topology matrix;

2. The method for protecting a power distribution network line according to claim 1, wherein the step of obtaining the topology structure of the power distribution network line corresponding to the power distribution network line protection request in response to the received power distribution network line protection request comprises:

3. The method for protecting a power distribution network line according to claim 1, wherein the step of performing fault judgment on the power distribution network line according to a preset fault line selection criterion and determining a fault line according to a judgment result comprises the steps of:

4. The method for protecting a power distribution network line according to claim 1, wherein the steps of extracting node information corresponding to the fault line nodes, constructing a fault information matrix, and constructing a fault location matrix by using the fault information matrix and the protection application topology matrix include:

5. The power distribution network line protection method according to claim 1, wherein the step of generating a corresponding trip command according to the fault location corresponding to the fault location matrix and executing a trip operation corresponding to the trip command comprises:

6. The power distribution network line protection method of claim 1, further comprising:

7. A power distribution network line protection system, comprising:

the protection domain static topology matrix module is used for sequencing each line node of the topology structure according to the line switch where each line interval is located, and generating a plurality of line node numbers; determining the order of a topological matrix according to the number of the line nodes corresponding to the topological structure; setting the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line nodes as an mth row matrix element corresponding to the topological matrix; wherein m is a positive integer; when a preset line node number is connected with the line node corresponding to the mth line node number respectively, and the preset line node number is larger than or equal to the mth line node number, setting a matrix element corresponding to the preset line node number in an mth row matrix as a first threshold element; when the preset line node numbers are connected with the line nodes corresponding to the mth line node numbers respectively, and the preset line node numbers are smaller than the mth line node numbers or the line nodes corresponding to the preset line node numbers and the mth line node numbers are not connected, setting matrix elements corresponding to the preset line node numbers in the mth line matrix as second threshold elements; setting one line node in the rest line nodes of the topological structure as a new mth line node, and performing jump execution, wherein the connection relation between the line node corresponding to the mth line node number corresponding to the topological structure and the rest line node is set as an mth row matrix element corresponding to a topological matrix; wherein m is a positive integer; constructing a protection domain static topology matrix by adopting a plurality of first threshold elements and a plurality of second threshold elements;

the protection application topology matrix module is used for extracting a fault line node corresponding to the fault line and a downstream line node corresponding to a downstream area of the fault line node; reserving matrix rows and columns corresponding to the fault line nodes and the downstream line nodes in the protection domain static topology matrix, and removing residual matrix rows and columns in the protection domain static topology matrix to generate a protection application topology matrix;

8. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the power distribution network line protection method of any one of claims 1-6.